IPC/WHMA-A-620 is the only industry-consensus standard that defines the requirements and acceptance criteria for cable and wire harness assemblies. Jointly developed by IPC (Association Connecting Electronics Industries) and WHMA (Wire Harness Manufacturer's Association), it serves as the universal reference for what constitutes acceptable workmanship in wire harness manufacturing.
If you're an engineer specifying a wire harness, a procurement professional qualifying a supplier, or a manufacturer building assemblies — this standard is the common language you share. Here's what it covers and why it matters.
What the Standard Covers
IPC/WHMA-A-620 provides detailed visual and dimensional criteria for evaluating wire harness workmanship. It defines three conditions for each inspection area:
- Target — the ideal, preferred condition.
- Acceptable — meets the requirements for the specified product class.
- Defect — does not meet the requirements and must be reworked or rejected.
The standard covers virtually every aspect of wire harness construction:
- Crimp terminations — crimp height, bellmouth, insulation support, conductor brush, and pull-force requirements.
- Solder terminations — solder flow, wetting, fill, and acceptable joint profiles.
- Insulation displacement connections (IDC) — conductor seating, insulation clearance.
- Ultrasonic welds — weld quality and integrity criteria.
- Wire routing and bundling — bend radius, wire crossings, tie placement, and lacing.
- Connector and terminal insertion — proper seating, retention, and pin alignment.
- Sleeving and protective coverings — heat shrink, braided loom, corrugated tubing, and tape application.
- Labeling and marking — legibility, placement, and durability.
- Molding and potting — overmold quality, voids, and flash.
- Coaxial and fiber optic assemblies — specialized criteria for RF and optical connections.
The Three Product Classes
One of the most important concepts in IPC/WHMA-A-620 is the class system. The standard defines three classes, each with progressively stricter acceptance criteria:
| Class | Name | Description | Examples |
|---|---|---|---|
| Class 1 | General Electronic Products | Function is the primary requirement. Cosmetic imperfections are more tolerable. | Consumer electronics, disposable products |
| Class 2 | Dedicated Service Products | Extended life and reliable, uninterrupted performance required. The most commonly specified class. | Industrial equipment, automotive, agricultural machinery, commercial products |
| Class 3 | High-Reliability Products | Continued performance is critical. Equipment downtime is unacceptable. Strictest criteria. | Life-support, military, aerospace, critical infrastructure |
The class determines how strictly each workmanship criterion is judged. A condition that's acceptable in Class 1 might be a defect in Class 3. Most industrial, automotive, and commercial wire harnesses are built to Class 2.
Why IPC/WHMA-A-620 Matters
Common Language
Without a shared standard, "good quality" is subjective. A-620 gives manufacturers, inspectors, and customers a common reference point — eliminating ambiguity about what's acceptable and what's not.
Consistent Quality
Manufacturers that train their assemblers and inspectors to A-620 produce more consistent results. The standard provides clear visual examples of target, acceptable, and defect conditions that operators can reference on the production floor.
Supplier Qualification
OEMs use A-620 compliance as a baseline for qualifying wire harness suppliers. A manufacturer that doesn't follow A-620 may not be able to compete for contracts in automotive, industrial, or defense markets.
Risk Reduction
Wire harness failures in the field are expensive — warranty claims, line shutdowns, safety recalls, and damaged customer relationships. Building to A-620 standards significantly reduces these risks by catching workmanship issues before they leave the factory.
Key Inspection Areas
While the standard covers dozens of inspection points, these are the areas that most frequently determine pass/fail:
- Crimp quality — the single most critical area. A bad crimp is the #1 cause of wire harness failure. The standard defines acceptable crimp height, bellmouth, insulation grip, and conductor visibility.
- Wire damage — nicks, cuts, or broken strands in the conductor that weaken the wire and can cause intermittent failures.
- Connector pin seating — terminals must be fully inserted and properly retained in the connector housing. Partially seated pins can back out under vibration.
- Strain relief — proper support at cable-to-connector junctions prevents wire fatigue and pullout.
- Wire routing — proper bend radii, no pinch points, adequate clearance from heat sources and moving parts.
How H&L Applies the Standard
At H&L Manufacturing, IPC/WHMA-A-620 isn't just a document on a shelf — it's built into our daily production process:
- Assemblers are trained to A-620 workmanship criteria
- Every harness undergoes visual inspection per A-620 before electrical testing
- 100% end-of-line continuity and short-circuit testing with integrated vision systems
- Crimp force monitoring validates every crimped termination in real time
- Cross-section analysis verifies crimp geometry on a sampling basis
- ISO 9001:2015 quality management system provides the framework for continuous improvement
Quality You Can Trust
H&L Manufacturing is ISO 9001:2015 certified, UL Approved, and builds every wire harness to IPC/WHMA-A-620 workmanship standards. With 59+ years of experience and customer excellence awards from Webasto and Alpine Electronics, we deliver the quality and reliability your product demands.
IPC/WHMA-A-620 FAQ
Common questions about the IPC/WHMA-A-620 wire harness workmanship standard.
Is IPC/WHMA-A-620 certification mandatory?
It's not legally mandatory in most cases, but many OEMs and industries require it as a contract condition. In practice, it has become the baseline expectation for any reputable wire harness manufacturer. If your manufacturer doesn't follow A-620, that's a red flag.
What is the difference between Class 1, Class 2, and Class 3?
Class 1 is for general-use products where function is the primary requirement. Class 2 is for dedicated-service products where extended life and reliable performance are expected — this is the most common class for industrial and automotive harnesses. Class 3 is for high-reliability products where failure is not acceptable, such as life-support, military, and aerospace applications.
What version of the standard is current?
The current version is IPC/WHMA-A-620E, released in 2024. It supersedes revision D (2020) and includes updated requirements and clarifications. Manufacturers should be building to the latest revision unless a customer specification calls out a specific version.
Does the standard cover crimping?
Yes — extensively. IPC/WHMA-A-620 defines acceptable and defect conditions for crimp terminations, including crimp height, bellmouth, insulation support, conductor visibility, and wire brush. Crimp quality is one of the most critical areas the standard addresses.
Does H&L build to IPC/WHMA-A-620 standards?
Yes. H&L Manufacturing follows IPC/WHMA-A-620 workmanship standards across all wire harness production. Every harness is visually inspected and 100% electrically tested. We also perform crimp force monitoring and cross-section analysis to verify termination quality.
What's the difference between IPC/WHMA-A-620 and IPC-A-610?
IPC-A-610 covers the acceptability of electronic assemblies (PCBs), while IPC/WHMA-A-620 specifically covers cable and wire harness assemblies. They're companion standards — a product that includes both a PCB and a wire harness would reference both.
Can I request a specific class for my wire harness?
Absolutely. The product class should be defined in your specification or purchase order. If no class is specified, Class 2 is typically assumed. If your application requires Class 3, discuss this with your manufacturer upfront — it affects inspection criteria, documentation, and cost.
How does IPC/WHMA-A-620 relate to ISO 9001?
They're complementary. ISO 9001 defines the quality management system — the processes, documentation, and continuous improvement framework. IPC/WHMA-A-620 defines the specific workmanship criteria for wire harness assemblies. A manufacturer should ideally have both: ISO 9001 for the system and A-620 for the product standard. H&L is ISO 9001:2015 certified and builds to A-620.