Colophon

This booklet was written for the customers of Page Electronica NV and addresses common design-related issues. Through close and accessible communication between the production facility and the R&D department, we strive to maximize the manufacturability of a PCB assembly.

High manufacturability ensures a cost-effective and highly reliable product.

We have deliberately avoided going too much into technical detail in order to keep the booklet readable. If you have any questions, please feel free to contact the process engineer for tailored advice.

Contact: bart.lozie@page.be

Process engineer.

The 3 Phases of Production

Prototype (α-series)
A prototype is an early model of a product, often partially assembled by hand, used to test the functionality or fit of components. To reduce costs and keep lead times short, it is a deliberate choice not to manufacture everything fully automatically at this stage.
However, do not assume that a functioning prototype proves that the design is ready for mass production.

Pilot Run (β-series)
After successfully completing the prototype phase, a pilot run is produced to verify whether the products meet all specifications and testing protocols as defined. During this phase, the various production processes are carried out as completely as possible and fine-tuned. The pilot run offers a more representative view of the eventual series production process.

Series Production
Following the prototype and pilot phases comes the actual series production. At this stage, we aim for the highest possible degree of automation. The focus is on minimizing the cost per unit and maximizing production yield.

Alternative Components

Long-Term Availability and Component Lifecycle Management

Unlike consumer electronics, service products are expected to offer replacement availability over an extended period. In sectors such as machinery and infrastructure, a replacement market lifespan of 15 years or more is often required.

However, the market for electronic components evolves rapidly, driven largely by the consumer electronics industry and its push for extreme miniaturization. As a result, components may become obsolete or unavailable much sooner.

To ensure long-term product continuity, designers must take into account the availability of alternative components and monitor the end-of-life (EOL) status of selected parts. This should already be considered during the design phase.

A reliable EMS (Electronics Manufacturing Services) partner will manage this process together with the designer, actively monitoring the EOL status of all components to initiate last-time buys, alternative part selection, or PCB redesign in a timely manner.

When it comes to alternative components, we distinguish two main categories:

• Function Compatible: The component provides the same functionality and is electrically suitable, but may differ in physical characteristics.

• Form-Fit-Function Compatible: The alternative is electrically identical and also matches the original component’s footprint and physical dimensions.

ESD: The Invisible Culprit

All non-conductive materials become electrically charged through friction with other materials in the triboelectric series. Everyone is familiar with the static shock felt when getting out of a car, combing hair, or the crackling sound when pulling on a woolen sweater.

Static discharges can reach voltages of over 50,000V. While this is merely unpleasant for humans, electronic chips—often sensitive to ESD at levels below 100V—can be severely damaged.

Damage caused to electronic chips by static discharge is called Electrical Overstress, or EOS.

It is important to understand that EOS damage caused by ESD is not always immediately apparent as chip failure. Instead, EOS can cause tiny burn spots inside the chip that may lead to premature failure months later.

Just as hand hygiene and wearing hairnets are mandatory and standard practice in the food industry, the electronics sector is obligated to work in an ESD-safe manner. The basic rule is simple and twofold:

• Everything conductive must be grounded.

• Everything insulating, which can generate charge, must be kept out of the ESD-protected area (EPA).

The human body is conductive, but our shoes are often insulating. To comply with the above rule, we must ground ourselves by wearing ESD shoes or grounding straps on the feet or wrist.
A wrist strap is mandatory when not standing directly on the ground, as grounding through the feet is then lost.

Our clothing, especially nylon, is insulating. It is best to keep nylon clothing (e.g., sportswear) out of the EPA.
If you wear insulating clothing underneath, cover it with ESD-safe clothing (Faraday cage principle). In other words, the outermost layer of clothing must be ESD-safe and enclose the other layers.

We strive to minimize insulating materials in the EPA: plastic bins are replaced by black conductive plastic bins, work surfaces are equipped with grounded conductive mats, packaging materials are purchased in dissipative versions, and so on.

Below you can see an example of LATI polymer material, which does not accumulate static charge, and ASA polymer material, which does.

Serial Numbers and Traceability in Electronics Manufacturing

Introduction

In today’s electronics industry, traceability—the ability to track products and components throughout the entire production chain—is a vital part of quality management and process control. Serial numbers play a central role in this system: they provide the unique identification that allows each product, component, or batch to be traced from basic material to end user.

Function of Serial Numbers

A serial number is a unique code assigned to each individual product or assembly. This code makes it possible to:

• Differentiate products within the same product family.

• Link production and test data to a specific item.

• Handle potential defects, failures, or recalls (RMAs) quickly and accurately.

In electronics manufacturing, serial numbers are automatically generated and printed on labels or directly laser-marked onto the printed circuit board (PCB). They are recorded in the Manufacturing Execution System (MES) or ERP system, together with all relevant production data.

At Page Electronica, we are transitioning from using serial numbers on labels to laser-marked serial numbers directly on the PCB. In this process, a small area of the solder mask is partially removed. Although the coating is not completely stripped, our preference is to mark within a copper-free area, avoiding any zones that contain tracks.

Data Structure

The serial number is applied as a 2D DataMatrix ECC200 code, and where space allows, it is also printed in human-readable format. The code contains both the production lot number and a unique serial number.

The minimum marking area is 5 x 5 mm; for legible human-readable text, a clearance area of at least 6 x 6 mm is required. Preferring a copper and silk free zone as mentioned above.

are available:

1	2	3

1. A unique datamatrix Sn°, on a thermal and wash resistant label, the minimum needed free space = 7x7mm

2. A laser marked datamatrix (preferred) containing a unique Sn° and the batch number + readable text, the min needed space is 6x6mm.

3. A laser marked datamatrix containing a unique Sn° and the batch number, there is no readable text. The min free area is 5x5mm

Traceability Levels

Traceability can be implemented at various levels:

1. Component level – Each electronic component (such as ICs or capacitors) is linked to a supplier, batch number, and purchase order.

2. PCB level – Each printed board assembly (PBA) receives a unique serial number used to store production parameters, test results, and software versions.

3. System level – The final product is assigned an overarching serial number that links all related subassemblies.

Benefits of Traceability

A well-implemented traceability system provides numerous advantages:

• Quality assurance: rapid identification and tracking of deviations or customer complaints.

• Process optimization: analysis of production data to identify trends or recurring issues.

• Compliance: adherence to standards such as ISO 9001, IPC-610, J-STD, and others.

• Efficiency in service and warranty: simplified identification of products in the field.

 Required Data for a smooth production startup

Please provide the IPC inspection class of your product, (IPC Class I: consumer products, Class II: service/industrial products, Class III: high-reliability and critical products).

This is important to determine what section of the production standard the assembly needs to comply with.

Revision and Documentation

Provide clear information regarding the current product revision, the revision buildup and revision history as the EMS-contractor needs to create a comparison between its own revision buildup and the one of the customer.

Bill of Materials (BOM)

A Bill of Materials for electronic assembly is a structured list that defines all components required to build an electronic product. A complete and production-ready BOM for PCB assembly (PCBA) typically includes the following elements:

• Item / Line Number

• Quantity per Board

• Reference Designators (e.g., R3, C12, U1)

• Component Description (e.g., “10 kΩ 1% 0603 resistor”)

• Manufacturer Name

• Manufacturer Part Number (MPN)

• Internal Part Number (if applicable)

Alternative Part List

An Alternative Part List contains substitute components for an original part. These alternatives may be used when the primary component is unavailable, obsolete, has a long lead time, or when cost reduction is desired.

Alternative parts are typically defined in two categories:

• Equivalent Parts – fully interchangeable with the original component, with identical form, fit, and function.

• Alternate Parts – interchangeable but with certain considerations (e.g., a capacitor with a different voltage rating or tolerance).

Selecting suitable alternatives requires verifying electrical compatibility, mechanical fit, and manufacturability, as well as considering cost, availability, and supply-chain stability. In some cases, consultation with component manufacturers or distributors may be necessary.

PSL Process Sensitivity Levels
Some components cannot be processed using standard methods because, for example, they are not resistant to reflow process temperatures or the usual cleaning agents, or they are sensitive to contamination by VOC’s... These are often sensitive sensors, LEDs, or high-capacity capacitors.
If you are aware that certain components are process-sensitive, please make sure to communicate this information to the production facility to prevent it from being overlooked.

Component Mechanical Datasheets

Many components have standardized package formats, such as 0402 and 0603 square chip components, or the complete Philips series including SOT23, SOT89, SO-8, and others.
Nowadays, however, many highly specific, unique, and odd-shaped packages are also being produced. LEDs and PCB-on-PCB modules are typical examples of this trend.
Please provide the mechanical datasheets for these components if they are difficult to find online.

GERBER RS-274-X (Extended Gerber)

RS-274-X is the most widely used file format for PCB manufacturing. Although there are substitutes like ODB++ that contain more data then Gerber, still gerbers is the main used format for production preparation. Always specify the required PCB thickness and special laminate requirements if any.

ODB++ (Siemens-Valor)

Siemens pushes the marked to obtain their new ODB++ standard, unfortunate this pushes the EMS-contractor to use exclusively rather expensive Siemens software. Other software sometimes can handle ODB++ files but only if exported with units standard set as imperial-inch.

PCB Manufacturer Working Files

These are the editable production files created by the PCB fabrication engineer.
Compared to the original Gerber files, manufacturer working files also include additional data such as:

• Breakaway and panelization details (e.g., rails, tabs, mouse bites)

• Added tooling features (fiducials, tooling holes, coupons)

• Manufacturing-specific adjustments and process notes

These files represent the version used directly for PCB production and may differ slightly from the customer-supplied data to ensure manufacturability.

Insert File

An insert file in electronics manufacturing is a data file that instructs the pick-and-place robots where and how to place each component on the PCB. It typically contains:

• Component identifiers (reference designators, e.g., R1, C5, U3) - Component designaters shall be limited to 5 characters. (e.g. IC123)

• X/Y coordinates on the PCB

• Rotation angle of each component

• Component type / package (e.g., 0402, SOT-23, QFN)

• Optional machine-specific details such as component height and nozzle selection

Insert files are usually generated from the PCB design software and then adapted to the format required by the specific placement machine. This ensures that the machine can accurately and automatically place components in their correct positions on the PCB.

IPC-D-356A

IPC-D-356 is an electronic netlist format used to unambiguously describe the electrical connections of a PCB.

It contains information about which pads and component pins should be electrically connected, including test points and sometimes impedance or reference information.

IPC-D-356 is used to verify that the produced board matches the design electrically, typically through a netlist comparison. Machines such as Flying probe testers are programmed using this file format.

IPC-2581 (optional)

• Open, XML-based format for exchanging complete PCB data.

• Contains all information required for production, assembly, and inspection, including layers, stack-up, dimensions, drills, netlist, component data, BOM, test points, and more.

Specification of Special Instructions

In IPC-A-610, the term “Not Established” indicates that no acceptance criteria have been defined for a particular feature. In other words, the standard does not specify whether the feature is acceptable, unacceptable, or allowable.

This does not mean that anything is automatically acceptable — it simply means that IPC-A-610 does not provide guidance for that specific characteristic.

For such cases, requirements must be agreed upon between the customer and the EMS provider. These special instructions should be clearly described.

Examples

• Specifying torque values for screw connections

• Any mechanical assembly requirements not covered by IPC-A-610

• Special coating, handling, or inspection instructions

Assembly Drawing

Supply a clear assembly drawing containing at least the following information:

• Pin-1 indication for components such as ICs and connectors.

• Reference designators (REFDES) for all components and unambiguous polarity markings (e.g., cathode indication). It is recommended to show these on the assembly drawing rather than relying solely on the silkscreen layer.

• Guidelines for AXI (Automated X-ray Inspection): specify which components require X-ray inspection and the desired sample rate. Note that AXI is not mandatory under IPC-A-610.

• Special handling and ESD requirements:

  • Clearly mark ultra-sensitive Class 0 ESD components, so additional precautions can be taken.

  • Standard electronics manufacturing environments are typically Class 1 compatible only, unless otherwise specified.

Testing

The customer may supply their own test system, or we as EMS-contractor can design and build a complete in-house solution. Both options are briefly discussed below, for more information contact the FAB-engineering.

Test system developed by the EMS contractor

Involves test-coverage analysis, hardware and software development, integration with traceability and validation.

The following items are necessary:

• Testpoint report: list of all testpoints and their function.

• Manufacturing data: PCB (Gerbers) and schematic.

• One functional (prototype) PCBA (single board or in cluster/panel).

Additionally the EMS-contractor offers Design-for-Test (DFT) support, assisting the PCB engineer in optimizing their design for testability.

Test system developed by customer and used in EMS FAB

Due to cybersecurity regulations (NIS2), external, unauthorized network devices are generally prohibited. Depending on the requirements the following options are possible:

1. The customer may supply their own hardware (e.g. laptop) only if network connection is not in any case required at the production site.

2. For testing in the project’s initial phase that require network connection, the EMS-contractor can provide a 4G/5G modem. This creates an isolated network, which is not architected to be used in mass production.

3. The FAB offers a dedicated server for functional testing in mass production. In consultation with the customer, a Virtual Machine is made available with network access. The necessary software and tools are installed and configured on the VM.

Conformal Coating Heatmap

Provide a heatmap for conformal coating that clearly indicates:

• Mandatory coating areas: zones that must be covered with conformal coating.

• Exclusion areas: zones that must remain free of coating (e.g., switches, sensors, connectors).

• Optional coating areas: zones where coating may be applied at the manufacturer’s discretion.

The heatmap should be precise and easy to interpret, ensuring the assembly team applies the coating accurately according.

Component Loss in Tape-On-Reel SMT Parts

SMT components are becoming increasingly smaller, sometimes barely visible to the naked eye. The vast majority of electronic components no longer have identification markings or text indicating their type. Larger components often have fragile leads or solder points, making reuse risky. Together, these factors mean we cannot assume SMT components can be placed manually.

SMT components, in all their diversity, must be supplied to the placement machine using feeders. Feeders open the component pockets and feed the machine with a new component after each pick-up.

Each setup requires loading the feeders, during which 1 to 2 components can be lost. Additionally, when unloading the feeder—if the reel is not fully used and production ends—2 components are inevitably lost.

Pick & Place Robots

Pick & Place robots quickly pick up and place these tiny components—sometimes at rates exceeding 20 components per second. This means the machine picks up 20 components every second, then checks their dimensions, corrects their position and rotation, and finally places them on the printed circuit board.

To maintain these high speeds, modern placement machines are designed to immediately reject and discard any component that deviates in size. This process is called machine spit-out.

Depending on the geometric complexity of the component, machine spit-out typically ranges between 0.05% and 0.20%.

Electronic Components and Moisture Sensitivity

Electronic components, especially plastic-molded SMT parts, are sensitive to moisture. Plastics are hygroscopic and absorb moisture from the air. When heated during the assembly process, the built-up pressure from trapped moisture can cause damage to the sensitive elements of the component.

The pressure from water vapor increases exponentially with rising temperature and becomes problematic for electronic components once temperatures exceed 200°C.

Damage to components or PCBs can vary and may include cracked silicone seals, delaminated bonding, twisted components causing soldering defects, blowholes, blisters, and more.

The factory closely follows the JEDEC J-STD-020 standard for soldering moisture-sensitive components.

Process sensitivity

To understand the process parameters for semiconductor components, datasheets are thoroughly reviewed. In most cases, the datasheet includes a dedicated section on the recommended process parameters.
For non-IC components, the situation is somewhat different; these datasheets are often brief and rarely contain the necessary process-related technical information.
The standard J-STD-075 defines PSL (process sensitivity levels) for non-semiconductor electronic components and categorizes them into component families.

Pt: Preheating temperature
TL: Time in liquidus
Tp: Peak temperature
Tpt: Time within 5°C of the peak temperature
#Reflows: Maximum allowed number of reflow cycles
** Temperature measured at the top-center of the component.

	Pt	Tl	Tp	Tpt	# reflow
Alu Elcap D ≤ 6.3mm H ≤ 4.5mm	100 – 150°C (90s)	30s >217°C	240°C	5s	2
Alu Elcap D ≤ 6.3mm H > 4.5mm	100 – 150°C (90s)	30s >217°C	250°C	5s	2
Alu Elcap D > 6.3mm ≤ 10mm	100 – 150°C (90s)	20s >217°C	240°C	5s	2
Alu Elcap D > 10mm	100 – 150°C (120s)	20s >217°C	230°C	5s	2
Plastic molded alu caps H ≥ 1.8mm < 12.5Volt	180°C max (120s)	60s >217°C	250°C	5s	2
Plastic molded alu caps H ≥ 1.8mm ≥ 12.5Volt	180°C max (120s)	30s >200°C	240°C	5s	1
Plastic molded alu caps H ≤ 1.1mm	180°C max (120s)	30s >200°C	240°C	5s	2
Film cap PPS	180°C max (120s)	30s >217°C	260°C	5s	2
Film cap non-PPS	180°C max (120s)	30s >217°C	240°C	5s	2
Plastic mould Polymer Tantalum cap ≤ 10Volt	180°C max (120s)	40s >217°C	250°C	5s	2
Plastic mould Polymer Tantalum cap > 10Volt	180°C max (120s)	30s >217°C	250°C	5s	2
Xtal oscillators	120s	90s	250°C	10s	-
Fuses	85s	65s	Zie Specs	20s	-
Inductors with insulated wires	100 – 150°C (90s)	60s	Zie Specs	20s	-
Non-solid state relais	Apply to specs
Leds	Apply to specs

Oxidation

Metals are sensitive to oxidation, which can occur in various forms and degrees and is not always detrimental. For example, tin, corten steel, or stainless steel form an oxide layer that protects the underlying metal from further corrosion.
The tin oxide layer changes color depending on its thickness. During reflow soldering, the warm air can cause oxidation on metal parts that are not in contact with solder fluxes.

• Up to 10 nanometers: transparent

• 10–15 nm: yellowish

• 15–20 nm: yellow-blue

• 20–30 nm: blue

• 30–50 nm: purple

• Over 50 nm: black

Up to 15 nm, there is little to no problem; once thicker, this can hinder the formation of a proper connection.

Metal oxides are generally less conductive; however, AgO₂ is actually more conductive than Ag.
Corrosion occurs when the metal degrades and loses its properties as a result of oxidation. This is often in combination with a catalyst, such as water, salty air near the coast, sulfur near industrial areas, or ammonia near intensive agriculture and livestock farming.
Due to the nature of electronic soldering, it is particularly susceptible to corrosion. In galvanic and electrolytic corrosion, an additional electrical voltage acts as a catalyst, accelerating deep corrosion.

Aqueous cleaning can also promote oxidation, so it is important to use additional corrosion inhibitors and ensure an efficient drying cycle.

Choice of production technology

The choice of production technology will determine how the final assembly is carried out. There are numerous methods to create electrical and mechanical connections, and it is advisable to consider the following points.

We distinguish several connection techniques: SMT reflow soldering, SMT wave soldering, PTH wave soldering, miniwave soldering (selective soldering), robot soldering, wire soldering, pin-in-paste soldering, press-fit connections, bonding using (anisotropic) conductive adhesives, and thermode soldering.

The price, durability, and control of the technology on the factory floor will influence the choice. You can combine multiple techniques, but each production step adds setup costs and increases production lead time.

Component selection

SMT offers higher yield and lower cost than PTH soldering, but only if all SMT components can be placed by machine. SMT parts that require manual placement due to packaging or complex geometry will result in lower yield.

Avoid using SMT connectors for applications involving repeated or heavy mechanical stress, as SMT solder joints have limited mechanical strength. PTH soldering performs significantly better in such cases.

Avoid components that require a specific production process, such as a single SMT part on an otherwise PTH board or vice versa. These create an additional and preferably avoidable production step.

Do not use chip components ≤0603 for SMT wave soldering.

Do not miniaturize unnecessarily. Follow component market trends that suit your product.

Reduce the number of different components. Check whether certain parts can be replaced with values already used elsewhere — not just across the board, but also per side. Moving a component to another side may reduce setup costs.

Avoid flexible connections. Flexible connections are significantly less reliable than fixed connections.

PIP soldering is only effective up to a PCB thickness of 1.6 mm.

Temp stress graph

SMT vs PTH

Surface mount technology (SMT) offers higher yield and lower assembly costs compared to pin-through-hole (PTH) technology. Assembly costs for SMT components are often only about one-tenth of those for PTH components.

However, this applies only if all SMT components can be placed by machines. SMT parts that require manual placement due to awkward packaging, complex shapes, or large sizes tend to result in lower yields and create bottlenecks in the production line.

Reduce the number of different components by checking if parts can be replaced with existing component values or packages. Do this not only for the PCB but also for each assembly side, as moving a component to the other side can reduce setup costs.

SMT in conventional wave soldering
SMT in conventional wave soldering is highly design-sensitive and subjects components to significant thermal shock, so it is strongly discouraged.
Do not use chip components ≤0603 in SMT wave soldering. Avoid unnecessary miniaturization and follow the component market trends for your product.

Mechanical strength
Avoid SMT connectors that will be subject to frequent or heavy mechanical stress, as SMT solder joints have limited mechanical durability. PTH solder joints perform much better in this regard.

Single technology
Avoid components that require a specific production process, e.g., a single SMT component on a PTH board or vice versa, as this creates an additional production step that is better avoided.

Pin-in-Paste (PIP) soldering
In pin-in-paste soldering, through-hole components are soldered using the SMT reflow process. The components must be THR (Through-Hole Reflow) compatible. PIP soldering is successful only up to a PCB thickness of 1.6 mm, and the pin-to-hole ratio is important.
(see chapter on PIP soldering)

Number and variety of components per board
While it is not always possible to control this, it is important to note that some placement robots have a maximum capacity of around 10,000 components per board per side, and about 200 different types (= feeder slots on a placement robot).
For manual through-hole assembly, smooth assembly is generally possible with a maximum of about 20 different types. More than 20 types manually placed tends to significantly increase the risk of errors.

V-groove

A V-groove or scoring can be applied to PCBs with a thickness ranging from 0.8 mm to 2.4 mm.

	Pcb thickness T1	Restmaterial T2
	0.8mm – 1.0mm	0.30mm ± 0.01mm
	1.2mm – 1.8mm	0.40mm ± 0.01mm
	2.0mm – 2.4mm	0.60mm ± 0.01mm
	A V-groove does not provide a perfectly precise separation, so please take this into account when determining the dimensions of the enclosure. It is recommended to include an additional margin of 0.1 mm. Copper traces on both outer and inner layers should be kept at least 0.4 mm away from the board outline.

Manually breaking a scoring line is not recommended, as it can introduce stress on components and solder joints, potentially causing damage or even breaking components. Depaneling is done using a rolling blade system, similar to a pizza cutter. It goes without saying that no components should extend over the scoring line, as they would be cut in two during the process. This blade system also requires some space, so it is advisable to place taller components at a greater distance from the scoring line. Next to this, you’ll find a drawing showing the dimensions of the cutting blade.

Contact terminals finish

The coating on contact terminals aims to provide a durable, low-resistance contact connection. The coating protects the connector or contact spring from forming metal oxides, as most metals are prone to corrosion when exposed to oxygen, corrosive gases, temperature fluctuations, moisture, and salts.

Gold and silver are popular choices due to their very low contact resistance and corrosion resistance. Nickel is a more economical option but has slightly higher contact resistance. A non-noble tin coating can also be used on contact connections, although the number of mating cycles is limited (< 50).

• For analog signals, a gold finish is essential, as well as for connectors used in industrial environments.

• Pure tin-coated contacts on data lines with a small pitch can sometimes experience whisker formation, which can be problematic. (see chapter on whisker formation)

Gold Embrittlement

A solder joint with a relatively high gold content, typically above 3 to 4%, will exhibit reduced strength. Both shear strength, impact strength, and thermal cycling performance show adverse effects from gold in the solder joint.

For gold-plated components in SMT, it is recommended to apply a pre-tinning process. In some cases, adding extra solder volume may be sufficient to achieve a strong enough solder joint. It is best to avoid gold-plated SMT components if there are tin-plated or partially tin-plated alternatives available.
Standards J-STD-001 and IPC-HDBK-001 describe good workmanship practices regarding gold embrittlement.

PLCC	connector	Partial tinned header

The amount of gold plating on a component can be determined from the relevant ASTM or MIL specifications. The thicker the gold layer, the more robust the connector will be against wear and exposure to reactive gases—but the less solderable it becomes.
In the case of Class II finishes, the gold layer must be removed from the solderable area as a preventive measure. (For Class I, it's recommended to calculate the impact before proceeding.)

Ag thickness	ASTMB488	MIL-G-45204
0.25um	Class 0.25	N/A
0.75um	Class 0.75	Class 0
1.25um	Class 1.25	Class 1
2.50um	Class 2.50	Class 2

Silver leads

Silver leads, also known as components with a Silver (Ag)/Platinum (Pt) coating, are prone to rapid oxidation. In particular, sulfur dioxide (SO₂) can severely affect the solderability of these components.
Ag/Pt-coated components must be protected as much as possible from air pollutants such as sulfur (S) and chlorine (Cl).
Components with silver-coated leads are often vacuum-packed, similar to MSL-sensitive components. However, unlike MSL-sensitive parts, these must not be dry-baked under any circumstances, and dry storage in a moisture-free cabinet is not a suitable alternative to vacuum packaging.

From a process perspective, there are additional constraints when working with Ag/Pt-finished components:

• The total soldering time (TAL) must be kept especially short.

• The peak soldering temperature should be kept low.

• Preferably, a solder alloy containing sufficient silver should be used to counteract leaching, such as Sn62Pb36Ag2 or the lead-free SAC405 instead of SAC305.

Package label

An Ag/Pt connection showing corrosion.

Different SMT components

SMT components come in a wide variety of packages. Select the package type thoughtfully to ensure that the technology generation on the board is as uniform as possible. Also consider the difficulty of inspection and repair when making your choice.

	Land grid array / No leads Inspection is difficult. (RX) Repair is complex.
	Pillar grid array Inspection is simple. (RX) Repair is complex.
	Ball grid array Inspection is simple. (RX) Repair is relatively simple.
	Column grid array Inspection is simple. (RX) Repair is complex.
	Bump grid array Inspection is simple. (RX) Repair is complex.
	Flat lug terminal Inspection can be difficult. (RX/AOI) Repair can be complex.
	End cap terminal Inspection is simple.(AOI) Repair is simple.
	Outward-L lead Inspection is simple. (AOI) Repair is simple.
	Gullwing lead Inspection is simple. (AOI) Repair is simple.
	Inward-L lead Inspection is simple. (AOI) Repair is simple.
	J-lead Inspection is simple. (AOI) Repair can be difficult.

Batteries

Storage of Large Quantities of Batteries
In volume assembly, large quantities of batteries are often required. Due to the real fire hazard they pose, many factories rightfully refuse to store them in the production hall or regular warehouse. This creates a logistical challenge.

For safety reasons, batteries are typically stored outside the main factory building, in a fireproof area physically separated from the production facility. Lithium-ion batteries carry the additional risk of high energy density, are extremely difficult to extinguish in case of fire, and are best stored at temperatures between 5°C and 20°C.

As a result, battery storage becomes an additional cost and a significant logistical challenge that should not be underestimated.

Overheating Due to Short Circuit
Connecting batteries to a PCBA before it has been properly functionally tested carries significant risk. The PCBA may still contain faults—such as a solder short—that can cause the battery to overheat rapidly, potentially leading to fire or even explosion.
Always opt for batteries with an internal overcurrent protection circuit.

Puncturing of Batteries
A PCBA often contains sharp components, from PCB edges to through-hole leads or pin headers. It is not unthinkable that, during handling, one of these sharp elements could puncture the battery. This can lead to ignition or explosion.
Preferably, only connect the battery right before the PCBA is placed into its final, secure enclosure.

Soldering of Coin Cell Batteries
Coin cells are sometimes soldered via the wave soldering process. In doing so, the battery becomes quite hot and is briefly short-circuited—both of which are unfavorable. While a coin cell can technically be short-circuited for up to 5 seconds, it is strongly discouraged.
A through-hole model with a slotted holder is preferred over a spot-welded version.

See also the chapter on long-term storage.

Solder ready model	Batteryholder

Fiducial markers

Fiducial markers are reference points used by assembly and automated inspection equipment. These markers allow machines to accurately determine the exact position of the PCB, as well as calculate and compensate for rotation, orientation, and board stretch.
If fiducial markers are missing, assembly accuracy is significantly reduced, and in some cases, automated assembly may even become impossible.

Fiducials on the PCB Panel
Three panel fiducials are placed along the edge of the panel. These are used to determine the rotation and orientation of the board.
If additional machining operations are performed after depaneling, circuit fiducial markers are also required.
Component fiducial markers are recommended for ultra-fine pitch (UFP) components on large boards.

Buildup

	A round pad with a diameter of 1.0 mm within a 2.0 mm solder mask clearance zone. Component fiducial markers may have a diameter of 0.50 mm. Avoid placing silkscreen text near fiducial markers, as this can interfere with optical recognition. For white solder mask, increase the solder mask clearance zone around the fiducial to a 3 mm square

Long board function

Standard placement machines are equipped to handle boards up to a size of 410 mm x 360 mm. Longer boards are possible, provided they are produced on machines equipped with a long-board function. When using this long-board function, the machine will load the board, partially assemble it, advance the board, and then continue assembling the remaining sections.

In the example below of an 800 mm board, the machine will assemble it in three steps (with two advances).
It is important to provide three sets of fiducial markers on the board to accurately determine its position after each board advance.

Solderpaste stencil design

Solder paste can be applied by dispensing, jetting (contactless pulsed dispensing), or screen printing. This section explains how to apply stencil design without going into detail about very specific footprints.

To achieve a durable solder joint, we always aim to provide the maximum possible amount of solder. More solder results in a mechanically stronger joint and a more flexible connection, which benefits durability. Naturally, problems caused by excessive solder—such as solder wicking, solder bridges, and skewing—should be avoided.

Before starting, the stencil’s Area Ratio (AR) must be determined. If the stencil’s AR is less than 0.66, the stencil will not function reliably. Preferably, the AR should be greater than 0.70.

	For square chip components, we reduce the stencil aperture by 40 to 50 µm around the solder pad. This is done to prevent solder from spreading beyond the solder island in the event of slight misalignment between the stencil and the PCB, which can cause mid-chip solder beads. 0201 components with an open window design can be used without any reduction.
	SOT components (small outline with gull-wing leads) are cut without reduction between the stencil aperture and the solder pad. Due to the component’s construction, it is insensitive to solder beads, and the extra solder is beneficial.
	For QFP components, we reduce the stencil aperture width by 40 µm on both sides and the length (at the toe and heel) by 25 µm. The purpose of this reduction is to minimize the risk of solder bridges.
	To avoid solder bridges, a general rule of thumb is to maintain a distance between two apertures greater than twice the thickness of the stencil. If this ratio cannot be achieved, options include reducing the stencil thickness, further reducing the aperture sizes, or creatively repositioning the apertures.
	In the case of a solder mask defined pattern, where the pads are drawn wider than the spacing, we reduce the pad width to achieve EPEG (Equal Pad Equal Gap).
	For QFN (no-lead) components, we reduce the exposed pad aperture to 60% of the original area when the area ratio (AR) of the leads is greater than 0.66. This ensures uniform solder paste volume, reduces the risk of solder splatter, and limits voiding.
	For QFN (no-lead) components, we reduce the aperture width by 40 µm (2 × 20 µm) and the length by 25 µm. The entire pattern is then shifted outward by 40 µm. This reduces the risk of solder bridges and promotes soldering with the wettable flanks.
	All apertures larger than 4 mm are symmetrically divided so that each individual aperture is smaller than 4 mm. The spacing (outgassing channel) between apertures is at least 300 µm wide. This reduces the risk of the scoop effect caused by the squeegee and improves outgassing.
	In designs with open vias, their use is preferably avoided. Solder paste printing into vias is detrimental, as it tends to create excessive air bubbles.
	Power SOP components have a stand-off; in these components, the thermal pad is slightly elevated and does not make direct contact with the pad. It is important that the applied solder paste thickness is at least equal to the height of this stand-off. If the stencil thickness is less than the component’s stand-off height, a step-up should be implemented at the thermal pad.
	For PICO size LGA components, we enlarge the smallest apertures to achieve a respectable area ratio (AR). This enlargement is done outwardly to prevent the risk of solder bridges.
	For BGAs with openings smaller than 400 µm, changing round apertures to square ones improves aperture fill quality.
	For micro BGAs (YZP), we enlarge the apertures to match the diameter of the BGA balls. In the example on the left, the pad was only 150 µm, while the micro BGA sphere had a diameter of 230 µm. We increase the aperture size to 230 µm to achieve a more stable paste deposit. Due to the 500 µm pitch, this does not pose a risk of solder bridges.
	For mechanical spacers, we provide as much solder as possible to create a strong meniscus. A crosshair design is necessary to avoid solder flowing into the via.
	For solder mask defined pads and copper defined pads, the solder volume/area should be equalized.
	Connectors and components subject to mechanical stress are provided with as much solder as possible—meaning no aperture reduction or oversizing is applied.
	Components with NIS contacts require at least 150 µm of solder thickness to achieve IPC-compliant fill.
	Connectors and components subject to mechanical stress are provided with as much solder as possible—meaning no aperture reduction or oversizing is applied.
	Areas where solder should not be applied must be removed from the stencil file, especially in cases of overlapping footprints—such as the JTAG connector shown on the left.
	For a step-up (where the stencil thickness is locally increased), keep the area as small as possible. For a step-down (where the stencil thickness is locally decreased), make the area as large as possible around the component requiring the step-down. Avoid changing the stencil thickness multiple times for the same component.
	Overlapping footprints, often used to accommodate two package variants of the same component, should always have one of the two omitted.
	For pin-in-paste connections, we enlarge the apertures (oversize) to increase the paste volume. Paste can extend up to 4.0 mm onto the solder mask, maintaining a minimum clearance of 300 µm from other solder pads.
	When applying oversize apertures, as shown here for this metal stud, it is important to maintain a 300 µm clearance from other pads or features, such as fiducials or milling lines.

Special pad modifications

In PCB locations with significant thermal imbalance, which can cause the tombstone effect, applying a "home plate design" can provide improvement.
The inverted home plate design is a solution to counteract mid-chip solder beads.
The MELF home plate design improves wetting for MELF components and reduces skewing.
Variants include round or elliptical shapes.

Layer marking

All the different layers in multilayer printed circuit boards should preferably be assigned a number, etched into the copper layer; starting with the top layer as layer number 1. The bottom layer is then marked in mirrored text, making it readable from the bottom side.

The layer marking clearly indicates the number of layers present and helps prevent misunderstandings during the layer stack-up process. For field returns, the layer marking is also useful, as it allows repair requirements to be identified even when the production documentation is unavailable.

Silkscreen design

If silkscreen is to be applied on the PCB to indicate the footprint, reference designator, or PIN1, ensure it is done in a uniform, clear, and organized manner. It is important that the silkscreen—especially the orientation marking—remains visible after the component has been placed.

• Silkscreen may discolor as a result of one of the thermal processes during production, depending on the type of ink used. Never use silkscreen to make a PCB white. Use a white solder mask for this purpose instead. (see chapter Permanent Solder Mask)

• For PTH components, a component outline and reference designator on the silkscreen are recommended.

• Avoid placing silkscreen in crowded areas, as this will only result in a cluttered layout and potential misunderstandings.

• Do not place silkscreen near or as an indicator for fiducial markers; the white print can cause recognition issues with automated systems.

• Avoid placing silkscreen near µ-BGA, UFP, QFN, flip-chip components, etc. In general, silkscreen should be avoided for fine-pitch SMT components.

• Include useful PCB information directly on the board to reduce the need for additional labels later. (see chapter Identification and Markings)

Silkscreen specs
Character height / width:	1.00 tot 1.35mm / 0.60 tot 0.76mm
Line thickness:	0.15mm tot 0.20mm
Clearance to solderable surfaces:	0.50mm

Silk buildup

SOT	Polarised condensator	Diode
Resistor or non polarised condensator	Elcap	BGA
QFN	DIL	QFP

PTH resistor	PTH Diode

Silkscreen under component bodies is not acceptable.

PCB Warpage (bow, twist, bending)

PCBs should be flat. IPC-A-610 specifies a maximum allowable bow and twist of 0.75%.
Board warping typically occurs during production and can lead to issues such as: open connections on large components, shorts under BGAs, and mechanical stress on solder joints after assembly. In some cases, a board may become so twisted that it becomes unprocessable in later production steps.

The primary cause of warping is a mismatch in the coefficient of thermal expansion (CTE) between the laminate and the copper, usually due to an imbalance in copper distribution either within a single layer or between layers.

Below is an example of a board that has remained permanently warped after the soldering process.

Warpage can be reduced by selecting a stiffer core laminate or by optimizing the copper distribution both within and between layers.
This can be achieved by adding dummy copper areas or copper dots. In some cases, the issue may also be caused by the fiber orientation of the laminate.

PCB laminate selection

FR-4, or Flame Retardant Grade 4, is the most commonly used laminate in service electronics.
Although this fiberglass mat + epoxy resin laminate includes "flame retardant" in its name, it is not necessarily UL94V-0 compliant by default.

Not all FR-4 materials are the same. In addition to dielectric specifications, several process-related properties must also be considered:

TG (Glass Transition Temperature):

This is the temperature at which the laminate loses its mechanical stability. Depending on the type of laminate, TG can vary from around 130 °C to 190 °C for high-TG materials.
The difference between the TG and the maximum process temperature determines the CTE-induced stress on vias.
For delicate PCBs with many or small-diameter vias, it is best to opt for a high-TG laminate.

TD (Decomposition Temperature):

This is the temperature at which the PCB material begins to chemically decompose.
In manufacturing, the TD must never be exceeded.
Fortunately, the TD is typically above 300 °C, while standard processing temperatures are below 260 °C.
However, during complex hot-air rework, local temperatures may temporarily exceed this.

CTE (Coefficient of Thermal Expansion):

This defines the thermal expansion behavior of the laminate.
PCB datasheets usually list three CTE values:

• CTE in the X-Y plane: Typically 10–20 ppm/°C

• CTE in the Z-axis (below TG): Around 50 ppm/°C

• CTE in the Z-axis (above TG): Around 250 ppm/°C

The CTE should be as close as possible to that of copper (16 ppm/°C) to minimize stress between the laminate and copper during thermal cycles.
Even after production, mismatched CTE values between the PCB and stiff component bodies can cause solder joint cracking.
Some components are available in both high-CTE and low-CTE versions for this reason.

Moisture Absorption:

This is the amount of moisture the PCB can absorb, typically ranging from 0.05% to 0.20% by weight. Moisture uptake can affect the thermal and electrical properties of the laminate, such as its dielectric constant.
In production, laminates with higher moisture absorption are more susceptible to blistering and delamination.

Hole spacing for axial components

Provide a footprint that ensures leads do not need to be bent too close to the component body, solder mask, or solder bends, as this can cause damage and lead to immediate rejection.

Ensure that L1 ≥ D1, with a minimum of 1 mm, to allow for automatic bending.

The through-hole length (L2) of the THT lead on the solder side is ideally 1 mm, with a minimum of 0.5 mm and a maximum of 2.5 mm.

The bending radius R1 depends on the wire thickness (D1):

• For wire thickness up to 0.8 mm: R1 = D1

• For wire thickness between 0.8 mm and 1.2 mm: R1 = 1.5 × D1

• For wire thickness greater than 1.2 mm: R1 = 2 × D1

The hole spacing (L3) should satisfy:
L3 ≥ Body + 2 mm + (3 × D1)

Permanent solder mask

Solder Mask Window
We opt for a copper-defined pattern. Only for µ-BGA, WLP, and CSP packages is a solder mask-defined pattern sometimes recommended. (See chapter CSP)
Use a solder mask opening that is 100 µm to 200 µm larger than the SMT solder pad (i.e., a clearance of 50 µm to 100 µm).

Solder Mask Color
The standard solder mask color is green; however, white, red, blue, yellow, or black are also possible. If there is no special reason, do not deviate from the standard green color just for aesthetic purposes. Green is the customary color for PCB manufacturers, and other colors usually require an additional production step.

It is also better to stick with the standard green mask during subsequent production stages.

Sensors and camera exposures are calibrated for the green reflectivity. Automatic Optical Inspection (AOI) systems need to be recalibrated for PCBs of other colors.
Additionally, different solder masks can cause variations in soldering effects on the solder joint and may require different baking processes.

Glossy vs. Matte Solder Mask
A glossy solder mask delivers the cleanest result after a no-clean wave soldering process.
A matte solder mask is often the better choice if you plan to apply a conformal coating later without the need to roughen the mask. (See chapter Applying Conformal Coating)
Avoid using overly dark solder masks, as they can hide delamination issues.

Masking on Vias
Cover as many non-solderable areas, tracks, and vias as possible with solder mask.
This prevents unwanted solder bridges or solder bleeding and makes the PCB easier to inspect.

Mask as Insulation
Solder mask should not be considered an insulating layer.
The mask is not designed to function as a voltage insulator, and there is no guarantee or control that the coating is fully intact.
In some areas, the mask thickness can be as thin as 5–7 µm.

Web VS Window

The smallest solder mask track commonly applied within a standard PCB price range is 100 µm with a 50 µm gap. For fine-pitch designs, however, this 50 µm gap and 100 µm mask track may sometimes be insufficient. In such cases, the PCB manufacturer will typically recommend converting the standard web design into a window design.

Mask web design	Mask window design

Do not do this without careful consideration, as it can lead to solder shorts.
Below are the layout guidelines for a successful window design.

Web pattern	Window pattern

In a web pattern, the pad width is half of the lead pitch—for example, for a 0.4 mm pitch, the pad width is 0.2 mm. When switching to a window pattern, do not just remove the mask tracks; also increase the pad width as shown in the sketch above.
The pad width should then be 0.25 mm.

Soldermask on via’s

There are several options for covering vias with or without solder mask:

• Exposed via: The via is completely free of solder mask.

• Partial covered via: The via opening is left exposed, while the annular ring is partially covered with solder mask.

• Via tenting: The via is fully covered with solder mask; however, openings may be present, so it is not guaranteed to be completely sealed.

• Plugged via: The via is fully blocked. (This is an additional manufacturing step.)

From a reliability standpoint, partial covered vias are preferred.

It is often mistakenly assumed that tented vias are fully sealed; however, this is not guaranteed and can cause issues such as conformal coating leakage.

X-outs

X-outs, also known as cross-outs, are defective boards within a panel that have been rejected by the PCB manufacturer.
The failed circuits are marked with an "X" by the manufacturer.

For the assembly facility, these X-outs are problematic because they must not be assembled and therefore need to be excluded from all inspection, testing, and assembly robots.

Preferably, we order PCBs without X-outs. This may involve additional costs from the PCB manufacturer. Boards with X-outs slow down the assembly process and will result in higher costs at the assembly facility.

If PCBs with X-outs are ordered, ensure BAD markers are provided (recognition points for robots to identify boards that must not be assembled).

High current design

We are frequently asked how large a via should be to ensure it can carry the same current as the trace. A simple rule of thumb is the following:

The via diameter should be one-third of the trace width, assuming the via wall thickness is half the copper thickness. For example, with 35 µm copper, the via wall would be approximately 17 µm thick.

However, because via plating thickness is not always consistent—and in some cases may be thinner than expected—we strongly recommend placing multiple vias and maintaining a generous safety margin.

If the PCB undergoes a wave soldering process, open vias will fill with solder, which can increase their current-carrying capacity. However, if you are working close to the limits and relying on solder filling, it is important to inform the production team about this requirement. There are plenty of online calculators available to determine how much current a trace can carry. It is crucial to consider cooling in these calculations. Ensure that traces carrying high currents are placed on the outer layers of the PCB, as this allows the trace to dissipate heat more effectively.

Thermal relief design for high current

For very high currents that need to be conducted from the top side to the bottom side of the PCB, it is recommended to duplicate as many solder pins as possible. In the above sketch, you can see that three pins of a connector have been duplicated. However, a thermal relief design must be applied to ensure smooth solder flow during the wave soldering process.

Thermal relief tracks limit current flow; to prevent these tracks from acting like fuses—even though there are 12 in this example above—we place enough vias around the solder pins. These vias help distribute the current, thereby relieving the thermal relief tracks.

Bendable PCB’s

As solutions for flexible substrates, there are Flexrigid, Full Flex, FR4 Semi-Flex, and Polyester PCBs.

	In a full flex PCB, components are also mounted on a flexible polyimide section. Usually, a stiffener is applied in that area to provide local rigidity.
	In a flex-rigid PCB, the components are mounted on a rigid section of the board, while the inner layers extend to form the flexible parts.
	A semi-flex FR4 PCB is a standard PCB where a portion is selectively thinned by milling, resulting in a remaining section thin enough to be bendable, typically around 100 µm thick. This is a simple solution suitable for electronics that need to be bent only once.
	Metal Jet Polyester PCB is a low-cost solution for single-layer flexible substrates, albeit with several limitations. The copper thickness is limited to 3 to 4 µm, and the polyester material can only withstand temperatures up to 150°C, which necessitates the use of low-temperature solder.

For full flex PCBs, tooling is required or careful design using rigid stiffener bezels.

Tin-whiskers

Tin whiskers form due to internal material stress combined with the growth of the Cu₆Sn₅ intermetallic compound (IMC) layer.
This internal stress initiates the growth of single-crystal whiskers from the tin layer.
These whiskers are typically about 1 µm in diameter and, in some cases, can grow up to 10 mm in length.

Tin whiskers most commonly occur on pure tin-coated components.
A similar phenomenon is observed with zinc, known as zinc whiskers.

Do not confuse whiskers with dendrite formation. Dendrites result from the migration of metal crystals caused by ionic contamination, moisture, and electrical stress.

Because the exact mechanism by which these conductive “antennas” grow is still not fully understood, and whisker growth can sometimes start immediately but often takes years to develop, tin whiskers pose a real risk to electronic products.
Data lines can be short-circuited, and there are documented cases where whiskers have withstood currents of up to several tens of milliamps before vaporizing.

Waterproof

After a negative experience, the question often arises: how to make electronics water-resistant? Electronics used in outdoor applications can become so degraded after just a few months that malfunctions occur. A moisture-tight enclosure is a must.

IP68 Enclosure
IP68 means: "dust-tight and waterproof, device remains usable under manufacturer-specified conditions."
This says little about moisture-tightness over weeks, months, or years; it only guarantees that no water enters the device for a certain period.
Water vapor molecules (H₂O gas) are about 400 times smaller than water droplets. While an enclosure might be waterproof for half an hour, it is not necessarily vapor-tight for long durations.

How to Achieve a Water-Tight Enclosure
Start with a good, sturdy IP68 enclosure. Metal is preferred over plastic because most plastics are hygroscopic.
Select an enclosure with enough screws or clamps so the sealing ring is firmly compressed. For a rectangular box, choose one where the screws are evenly spaced for uniform pressure on the seal.
Enclosures with clamps have the advantage of simpler O-ring designs and a predetermined clamping force. Opt for enclosures with mounting holes outside the chamber or with a mounting bracket.

Cable Glands and Cable Entry
Enclosures with molded-in cable glands are preferred, as this saves a seal and prevents glands from loosening.
Ideally, route all cables through the bottom of the enclosure.

Reducing Salts on the PCB
Salts are a major cause of corrosion; combined with moisture and bias voltage, salts initiate electromigration.
Removing salts from the circuitry is a crucial step. This requires washing the electronics.

Potting and Conformal Coating
Applying conformal coating will not make your circuit waterproof but serves as a good corrosion inhibitor and protects against condensation. A coating will definitely help extend your electronics’ lifespan.
Potting the electronics, however, does provide waterproofing. Components with screw connections or moving parts usually cannot be potted. Partial potting is often a good alternative.

Long time storage

Long-Term Storage Considerations

By long-term storage, we mainly mean a duration exceeding the manufacturer’s guaranteed shelf life. Components, PCBs, or complete assemblies often need to be stored for extended periods. This can have various reasons—for example, due to MOQ (minimum order quantities), surplus parts are kept in stock. Bare PCBs or custom parts are often purchased in larger batches to reduce costs and processed over time. Assemblies may also be stored waiting for installation. Additionally, parts may need to be stocked for up to 15 years to guarantee availability for the aftermarket.

Shock Resistance
Parts stored for long periods will likely be moved multiple times. Use robust, shock-resistant packaging.

ESD Protection
ESD-safe packaging prevents buildup of static charge that can damage sensitive semiconductors.
Avoid using foam and plastic materials that generate static, as well as printed paper and packaging tape, which can induce high static charges. Dissipative materials with antistatic additives (such as pink poly bags) generally guarantee antistatic properties for only about six months.

Contamination
Initially, contamination means dust, which can originate from cardboard boxes or packaging materials themselves. Dust can cause shorts or damage open chip sensors and similar components.
Handling and repeated touching of parts can deposit oils, salts, and other residues that cause long-term damage.
Take precautions against contaminated or aggressive air, such as oil vapors.

Moisture Protection
Parts, especially plastics, absorb moisture and can suffer moisture damage during soldering, notably MSL-sensitive components and PCBs.

Corrosion
Metals can corrode during long storage due to exposure to aggressive air, moisture, or the presence of acids and salts (e.g., salty air, ammonia, chlorine, sulfur, or vapors from acidic silicones).
Assemblies should be stored in airtight packaging with desiccants and/or anti-tarnish strips.
For very long storage, assemblies should be cleaned of flux residues.

Condensation Resistance
Components can be sensitive to condensing air, especially pre-installed electronics and nearly hermetically sealed parts. Relays can also be susceptible to condensation damage.

Solderability
The solderability of nickel-plated parts, OSP or ENIG PCBs, brass solder contacts, etc., can degrade and complicate later processing.

Diffusion
Intermetallic growth can impair solderability. Keep this in mind regarding the shelf life of tin-plated items like HASL PCBs and tin-plated leads.

Tin Whiskers
Pure tin components can exhibit whisker growth. Tin whiskers can cause solder shorts on data lines; these are mainly chemically tin-plated parts.

Tin Pest
Tin stored at low temperatures can degrade itself. The tin structure changes from beta-tin to alpha-tin.

Plastic Embrittlement
Plastics age and become brittle due to UV exposure, the action of gases, and drying out. Prolonged storage at elevated temperatures can also affect the durability of plastics, primarily causing a loss of flexibility.

Aging of Electrolytic Capacitors
The quality of the electrolyte and the storage temperature are the main factors determining how long a capacitor can be stored before it loses its specified characteristics.

Energy loss

Batteries must not lose their energy. Ensure there is no standby current drain during storage, and avoid conductive packaging that can discharge the battery. Lithium batteries have the longest lifespan, exceeding 15 years..

IP protection (intellectual property)

Protecting your design against intellectual theft, cheap copies, or making it completely tamper‑proof is not straightforward. Conversely, reverse engineering is also not easy — once you make it difficult for a pirate, there is a good chance they will fail to copy your design.

Intellectual theft often occurs when competitors try to extract your know‑how to integrate it into their own designs.

Making a product tamper‑proof (or tamper‑evident) is aimed at preventing unauthorized opening of the device, which could affect operation or void the warranty.

Counterfeiters may reproduce an entire product to sell a cheaper version, sometimes using identical housings and markings to mislead consumers.

Discouraging piracy

Sell your product at a fair price through a network that provides good service. This is the most obvious solution — “if there is no treasure to be gained, there is no thief.”

Protect yourself legally with patents and copyright. In any case, include “Patent pending” and copyright markings.

Apply a recognizable logo or product name so customers do not inadvertently fall for look‑alike items.

Continuously improve your design so copycats are always playing catch‑up — time is their greatest enemy.

Secure your production chain

Use robust NDA contracts and work with trustworthy partners. Pure EMS companies usually have no interest in stealing your ideas; an EMS that also performs R&D in the same sector is a higher risk.

Consider internal confidentiality too — dismissed employees sometimes take more know‑how than they are entitled to.

Don’t outsource the entire work package to a single subcontractor. You can split tasks, for example:

• Order the PCB yourself from the board house.

• Purchase delicate ICs yourself and re‑code/program them; if programming services are needed, outsource that to a different party than the EMS.

• Store design data securely and preferably split across multiple locations — piracy often starts with stolen CAD data via hacking.

Protect against tampering

• Use tamper‑proof screws, hidden screws, and tamper‑evident labels.

• Consider clever countermeasures (e.g., circuitry that erases chip memory or disables sensitive components when the enclosure is opened improperly).

Make reverse engineering difficult

• Remove textual markings from ICs — this already makes reverse engineering harder.

• Apply a hard‑to‑remove coating over dense chip areas. This won’t stop a professional pirate but will deter hobbyists.

• Use passive components without value markings.

• Add false traces in inner layers and use copper pours to make X‑ray copying very difficult.

• Use custom ASICs — these make reverse engineering virtually impossible.

Component supply

Components must be supplied in production-friendly packaging to enable efficient, reliable, and fast feeding into the machines.

Even in the case of prototyping—where full packaging quantities are preferably avoided—machine-friendly packaging is still preferred. SMT components are often small, fragile, and no longer easy to place manually. The absence of standardized packaging can result in components being placed incorrectly.

Componenttypes	Voorkeur verpakking
Chip components (square chip & melf)	Tape on reel
SOP (small outline packages)	Tape on reel
QFP	Tray
Small size BGA & QFN up to 20x20mm	Tape on reel
Larger BGA's	Tray
Shielding	Tray of Tube
SMT Connectors	Tape on reel up to 44mm, take info for larger connectors

VOC’s

“Volatile Organic Compounds” (VOCs) are often discussed in the context of environmental and emission regulations, but they can also cause issues with LEDs.

This is especially relevant in weatherproof, hermetically sealed electronic assemblies, where VOCs can negatively impact the lifespan and light output of LEDs. VOCs migrate into the silicone lens of the LED and condense on the LED die. LEDs that emit white or blue light are particularly sensitive to this.

VOCs are commonly used chemical compounds found in solder fluxes, adhesives, coatings, O-rings and seals, potting compounds, etc. These materials are frequently used in electronics and can release VOCs through outgassing or when heated. In an enclosed environment, such VOCs can adversely affect the performance of nearby LEDs.

VOC-related LED issues can be recognized by a cloudy lens or a brownish deposit on the die. In most cases, this results in a noticeable drop in light output. In some instances, the LED may begin to flicker or fail completely.

Ultrasonic Welding of Plastic Housings

Ultrasonic welding is a widely used technique for joining plastic parts—such as enclosures or housings—quickly and securely without the use of adhesives, screws, or other fasteners. It is commonly applied in industries like electronics, automotive, medical devices, and consumer products to achieve a strong watertight seal.

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Advantages of Ultrasonic Welding

• Fast: Welding takes less than a second in most cases.

• Strong and reliable: The joint is as strong as the base material.

• No extra materials needed: No glue, screws, or solvents required.

• Easily automated: Suitable for high-volume production.

• Environmentally friendly: No emissions or waste from adhesives or solvents.

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Limitations

• Material compatibility: Only thermoplastics can be used. Ideally, both parts should be made of the same material.

• Design constraints: Parts must be specifically designed for ultrasonic welding (e.g. with energy directors).

• Size limitations: Large parts are harder to weld due to vibration dispersion.

• Aesthetic impact: Weld lines or minor surface deformation may occur.

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Common Plastics Used in Ultrasonic Welding

• ABS (Acrylonitrile Butadiene Styrene)

• Polypropylene (PP)

• Polycarbonate (PC)

• Polystyrene (PS)

• Nylon (PA)

• PVC (in some cases)

Different plastics can sometimes be welded together, but only if they are thermally and chemically compatible.

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Typical Applications for Plastic Enclosures

• Electronic housings (e.g. remote controls, sensors)

• Medical devices (e.g. disposables)

• Automotive components (e.g. dashboard sensors)

• Consumer products (e.g. chargers, battery cases)

• Portable devices (e.g. Bluetooth speakers)

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Design Tips for Ultrasonic Welding

When designing a product or enclosure for ultrasonic welding, consider:

• Weld geometry (e.g. small triangular ribs called energy directors)

• Alignment features (e.g. guide pins, snap fits)

• Sonotrode access (the weld area must be reachable by the horn)

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Main Risks

1. Mechanical damage from vibrations

• Vibrations can travel through the plastic into internal PCBs and components.

• This may result in:

  • Cracked solder joints

  • Broken IC bond wires

  • Fractured ceramic capacitors and Kristal components

  • Loose connectors or internal cables

2. Overheating from localized heat

• The melting process at the weld interface can generate heat that spreads to nearby parts.

• Consequences may include:

  • Thermal degradation of temperature-sensitive components

  • Plastic deformation of housings or connector parts

  • PCB delamination in multilayer boards

3. Damage to sensors and MEMS devices

• Ultrasonic vibrations are especially harmful to:

  • MEMS sensors (e.g. accelerometers, gyros)

  • Microphones and audio components

  • Components with moving parts (e.g. hard drives)

• These may be permanently damaged or provide incorrect measurements.

4. Loss of calibration

• Precise sensors or measuring devices can become miscalibrated due to micro-shifts or internal stress.

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Best Practices to Minimize Risk

Measure	Description
Keep sensitive parts away	Place components far from the weld area.
Use vibration dampers	Introduce damping materials or structural isolation between housing and PCB.
Secure fixture design	Use a custom fixture to minimize vibration transfer to the electronics.
Use low-energy settings	Reduce welding time, pressure, and amplitude.
Isolate PCB mounting	Mount PCBs using rubber grommets or floating supports.
Conduct thorough testing	Test prototypes with stress, X-ray, or functional checks.
Consider alternatives	If ultrasonic welding is too risky, use other bonding systems instead.

Abbreviations

AOI: Automatic optical inspection.

BGA: Ball grid array.

CSP: Chip scale package.

EMS: Electronic manufacturing supplier.

ENIG: Electroless Nickel Immersion Gold.

EOL: End of life.

EOS: Electrostatic overstress.

EPA: Electrostatic protected area.

ESD: Electrostatic discharge.

FR4: Flame Retardant 2.

FR4: Flame Retardant 4.

GND: Grounding.

HASL: Hot air solder level.

LGA: Land grid array.

MAR: Mask Annular Ring.

MOQ: Minimum order quantity.

MSL: Moisture sensitivity level.

NSMD: Non-soldermask defined.

OEM: Original equipment manufacturer.

OSP: Organic solderability preservative.

PCB: Printed circuit board.

PIC: Programmable interrupt controller.

PTH: Plated through hole.

PSL: Process sensitivity level.

NPTH: Non plated through hole

QFN: Quad flat package No-lead.

QFP: Quad flat package.

RTV: Room temperature vulcanisation.

RX: Röntgen onderzoek.

SMA: Surface mount assembly.

SMD: Surface mount devices. OF solder mask defined.

SMT: Surface mount technology.

SOT: Small outline transistor.

UFP: Ultra fine pitch.