In the wire harness manufacturing industry, quality is not a matter of opinion — it is defined by standards. The IPC/WHMA-A-620, officially titled “Requirements and Acceptance for Cable and Wire Harness Assemblies,” is the only industry-consensus standard that addresses wire harness and cable assembly workmanship. Understanding this standard is essential for anyone involved in specifying, manufacturing, or inspecting wire harness assemblies.
What Is IPC/WHMA-A-620?
The IPC/WHMA-A-620 standard was developed jointly by IPC (Association Connecting Electronics Industries) and WHMA (Wire Harness Manufacturers Association). It establishes the criteria for producing quality wire harness and cable assemblies, covering everything from crimping and soldering to wire routing, lacing, and connector assembly. The standard provides visual examples and measurable criteria that inspectors and operators use to determine whether a given assembly meets acceptable workmanship levels.
Unlike internal company standards, IPC/WHMA-A-620 is recognized globally. This means that a wire harness built to A-620 standards in Türkiye meets the same quality benchmarks as one built in Germany, Japan, or the United States. This universal language of quality is what makes the standard so valuable in global supply chains.
The Three Workmanship Classes
One of the most important concepts in IPC/WHMA-A-620 is its three-tier classification system. Each class defines a progressively stricter level of workmanship and inspection.
Class 1: General Electronic Products
Class 1 applies to products where the primary requirement is function of the completed assembly. This is the least stringent class and is typically used for consumer electronics and non-critical applications. Cosmetic imperfections are generally acceptable as long as they do not affect functionality.
Class 2: Dedicated Service Electronic Products
Class 2 covers products where continued performance and extended life are required but uninterrupted service is not critical. This class is the most widely specified in industrial, commercial, and automotive wire harness applications. It requires higher workmanship standards than Class 1, with tighter tolerances on crimps, solder joints, and cable routing.
Class 3: High-Performance Electronic Products
Class 3 is the most demanding level, intended for products where continued high performance or performance on demand is critical. Failure is not an option. This class applies to aerospace, military, medical life-support, and other mission-critical wire harness applications. Every aspect of the assembly is held to the tightest tolerances, and inspection requirements are the most rigorous.
Key Inspection Criteria in IPC/WHMA-A-620
The standard covers a wide range of inspection points. Here are the most critical areas that directly impact wire harness quality and reliability.
Crimp Terminations
Crimping is the most common method for terminating wires to connectors. A-620 defines acceptable crimp height, width, and bellmouth dimensions. It specifies how much insulation can extend into the crimp barrel, how many wire strands may be damaged or missing, and the required pull force values. A proper crimp must form a gas-tight connection that maintains electrical integrity over the life of the product.
Soldered Connections
For soldered wire harness terminations, the standard defines acceptable solder fillet shape, wetting, and coverage. It identifies defects such as cold solder joints, solder bridges, insufficient solder, and excessive solder. Proper soldering technique is essential for reliable electrical connections, especially in environments subject to vibration and thermal cycling.
Wire Routing and Bundling
The standard addresses how wires should be routed, bundled, and secured within a harness assembly. It covers minimum bend radii, cable tie placement and tension, lacing techniques, and the use of protective sleeves and conduits. Proper wire routing prevents chafing, reduces electromagnetic interference, and ensures the harness fits correctly within the final assembly.
Insulation and Jacketing
A-620 specifies requirements for wire insulation integrity, including acceptable limits for nicks, cuts, and abrasion. Damaged insulation can lead to short circuits, arcing, or complete system failure. The standard also covers heat shrink tubing application, ensuring proper shrink ratio, adhesion, and coverage of the connection area.
Why IPC/WHMA-A-620 Compliance Matters
Specifying IPC/WHMA-A-620 compliance in your wire harness requirements provides several benefits. It establishes a clear, objective quality benchmark that eliminates ambiguity between you and your supplier. It reduces the risk of field failures by ensuring consistent workmanship. And it provides a common framework for resolving quality disputes — both parties can reference the same standard rather than arguing subjective opinions.
SIMKAB and IPC/WHMA-A-620
At SIMKAB, we manufacture wire harness assemblies in accordance with the IPC/WHMA-A-620 standard. Our production operators are trained on A-620 workmanship criteria, and our quality control processes incorporate the standard’s inspection requirements at every stage of manufacturing. This commitment to recognized industry standards is one of the ways we ensure that every wire harness leaving our facility meets the highest quality expectations.
Need a wire harness manufacturer that builds to IPC/WHMA-A-620 standards? Request a quote from SIMKAB and let us show you what standards-driven manufacturing looks like.
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