When connecting cable assemblies to PCBs, you need more than just a physical connection. These interfaces must meet specific industry standards to deliver minimal performance across different applications. Understanding the right standards for your project is necessary when applying to both consumer electronics and aerospace systems. This FAQ discusses the most common standards for the wire harness-to-PCB interface.
Q: What is the IPC/WHMA-A-620 standard, and how do its classes affect connections?
A: The IPC/WHMA-A-620 standard is the main rulebook for making cable and wire harness assemblies in electronics. It shows manufacturers exactly what makes a good assembly and what does not. These rules help companies establish wire connections that function properly and last a long time, depending on their intended use.
Q: What is the IPC/WHMA-A-620 standard, and what requirements does it establish?
A: The IPC/WHMA-A-620 standard, called “Requirements and Acceptance for Cable and Wire Harness Assemblies,” gives a complete set of rules that covers many important steps:
- Wire preparation and crimping — specific requirements for stripping wire ends and creating proper crimp terminations.
- Soldered interconnections — acceptance criteria for solder joints within harness assemblies.
- Connectorization — requirements for contacts within connector housings and their termination to wires.
- Testing methodology — standardized inspection procedures, including visual examination and electrical testing.
Q: How do terminal lead/wire placement requirements differ between product classes?
A: Terminal lead/wire placement specifications vary significantly between classes, as illustrated in Figure 1. This table presents a systematic analysis of acceptable defect measurements across different terminal types.
For turret and straight pin terminals, Class 1 permits defects of less than 90°, while Class 2 introduces a distinction between defects of less than 90° and those between 90° and 180° (requiring a process indicator). Class 3 maintains the strictest standards, allowing only defects less than 180°.
Bifurcated terminals have a single specification across all classes – defects must be less than 90°. Hook terminals follow the same pattern as turrets and straight pin terminals across the three classes.
For pierced or perforated terminals, Class 1 requires the wire to make contact with the terminal surface, while Classes 2 and 3 share the requirement that defects must be less than 90°.
These different levels of rules let manufacturers choose the right quality standard for how their products will be used. This helps them balance making products that are affordable while still being reliable enough for their intended use.
Q: What does J-STD-001 require for soldering wire harnesses to PCBs?
A: The IPC J-STD-001 standard is another reference for soldering processes in electronics manufacturing. When connecting wire harnesses to PCB assemblies, this standard becomes especially relevant, as it governs the quality of the soldering interface. Let us examine how this standard applies to your manufacturing process and what specific requirements you need to meet.
J-STD-001 establishes specific requirements for solder connections that directly impact the reliability of wire-to-PCB interfaces. For through-hole soldering, common in wire connections, the standard requires that the plated through-hole (PTH) be filled with solder. It also needs proper wetting of the barrel and leads.
As shown in Figure 2, Class 3 applications require:
- 75% PTH fill minimum
- 270° circular wetting on the component side
- 330° circular wetting on the solder side
These measurements are not arbitrary, as they directly correlate with connection reliability. The circular wetting pattern shown on the right side of the figure demonstrates how solder must flow continuously around the barrel. When inspecting your connections, you can use this visual reference to quickly assess if your soldering process meets Class 3 standards.
Q: How do product classes under J-STD-001 affect soldering requirements for wire harness connections?
A: The J-STD-001 standard defines three product classes that correspond to different reliability requirements:
- Class 1 — consumer electronics requiring basic functionality and less stringent requirements.
- Class 2 — service electronics requiring extended performance and moderate standards requirements.
- Class 3 — high-performance electronics requiring continuous performance and the most stringent requirements.
For wire-to-PCB connections in Class 3 applications, such as military or medical equipment, the standard imposes stricter guidelines for the quality of solder joints. This includes more precise requirements for wire preparation, terminal mounting, and the formation of solder fillets.
Class 3 also requires more thorough inspection procedures. While visual inspection is effective for many aspects, X-ray inspection may be necessary for partially hidden connections, which are common in compact wire-to-PCB interfaces.
Decide your product class early in the design process. This choice will guide your material selection, process controls, and quality acceptance criteria during manufacturing.
Q: When do AS9100 and IATF 16949 standards apply to wire harness connections?
A: AS9100 and IATF 16949 represent specialized standards that build upon basic IPC requirements. AS9100 applies to aviation, space, and defense products, while IATF 16949 focuses on automotive manufacturing. Each standard adds industry-specific requirements beyond technical specifications.
For wire harness-to-PCB connections, AS9100 emphasizes reliability through controlled manufacturing processes. You must establish documented procedures for wire preparation, terminal attachment, and PCB soldering. The standard requires proper assembly verification procedures, complete parts traceability, current assembly instructions, and connection testing protocols.
The standard addresses common failure modes such as insufficient wire length, causing stress on connection points, and improper force distribution in FFC and FPC connectors. Figure 3 illustrates these failure modes to help you identify and prevent connection problems during design and assembly.
IATF 16949 extends the requirements of ISO 9001, specifically for automotive manufacturing. Wire harness-to-PCB interfaces in vehicles must withstand harsh environmental conditions while maintaining electrical integrity for power distribution and signal transmission. The standard emphasizes failure prevention through Advanced Product Quality Planning, which helps identify potential connection issues during the design phase.
Automotive applications need environmental resistance testing for temperature, vibration, and humidity conditions. You also need long-term reliability validation, complete component traceability, and process control verification. For electric and autonomous vehicles, these connections carry both high-power and signal transmission requirements, making compliance essential for vehicle safety and performance.
Conclusion
Choosing the appropriate standard depends on your application requirements and reliability expectations. Consumer electronics use IPC/WHMA-A-620 Class 1 for general applications. Industrial equipment benefits from Class 2 standards for extended performance. Medical and military applications require Class 3 for high reliability, as connection failure poses significant safety risks.
Aerospace applications require AS9100 compliance that extends beyond technical standards. Automotive applications require IATF 16949 for environmental and safety requirements. Consider cost implications when selecting standards, as higher classification levels need more rigorous testing and documentation. Balance these requirements against your reliability needs to select the most appropriate standard.
References
Lean Six Sigma Implementation in Cable Harness Manufacturing, International Journal of Mechanical and Production Engineering
Driving Excellence Embracing IATF 16949 Standards for Superior Quality and Traceability in Automotive Electronics, Cogiscan
IPC Class 2 vs Class 3: Understanding the Critical Differences in Electronics Manufacturing Standards, Wevolver
IPC Standards: The Definitive Guide for Electronics Engineers and PCB Designers, Wevolver
IPC class standards for classes, 1, 2 and 3 – Definitions and Examples, The Electronics Group
AS9100D Certification: Why it Matters for Aerospace PCB Manufacturing, PCBnet
Establishing Advanced Product Quality Planning (APQP) in IATF 16949, Advisera
What is the IPC/WHMA-A-620 Standard in PCB Manufacturing?, PCB Directory
How manufacturers of wiring harnesses can ensure traceability, Wire Draht
Common Pitfalls of Wire Harness Design and How to Avoid Them, Zuken
AS9100 Rev D Documentation Requirements, The AS9100 Store
IPC/WHMA-A-620, Wiring Harness Manufacturer’s Association
IPC J-STD-001 Standard for Soldering, Sierra Circuits
Handling Precaution for Terminal and Connector, JST
AS9100 Terms & Conditions, Hofman Engineering
What is IPC A-620 Training Program, SlideShare
IPC J-STD-001 for Operators SYLLABUS, IPC
AS9100 Risk Management, The AS9100 Store
Accreditations and quality, Nemco Limited
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Filed Under: Connector Tips