IPC/WHMA-A-620 Cable Assemblies: What OEMs Should Look for in Workmanship

IPC/WHMA-A-620 is the globally recognized standard for cable assembly and wire harness workmanship. Most OEMs require their contract manufacturers to be certified—but far fewer take the time to understand what the standard actually governs or how it should be applied in day-to-day production.

That gap matters. Certification alone does not guarantee consistent quality, reliability, or long-term performance. To truly de-risk their supply chain, OEMs need to understand the key workmanship requirements defined by IPC/WHMA-A-620 and know what to verify when qualifying a cable and wire harness manufacturer.

This guide breaks down the most important IPC practices, and the quality indicators OEM teams should evaluate.

What Is IPC/WHMA-A-620 for Cable Assemblies?

IPC/WHMA-A-620 defines the manufacturing, inspection, and testing requirements for cable assemblies and wire harnesses. It establishes uniform criteria for acceptability, ensuring assemblies meet defined electrical, mechanical, and visual standards.

The specification is organized into three workmanship classes:

• Class 1 – General consumer electronics

• Class 2 – Commercial and industrial products

• Class 3 – Aerospace, medical, defense, and other mission-critical systems

Most industrial, aerospace, and medical OEMs require Class 3 workmanship, which carries the tightest tolerances and highest reliability expectations.

Key Workmanship Elements OEMs Should Evaluate

1. Soldering Quality

Poor solder joints are among the most common causes of premature field failures. IPC/WHMA-A-620 provides detailed criteria for acceptable soldering that go far beyond a visual “pass/fail.”

OEMs should ensure their contract manufacturer consistently verifies:

• Proper solder wetting

• Absence of cold solder joints

• No solder balls or bridging

• Minimal solder wicking into conductors

Consistent solder quality directly impacts electrical performance, vibration resistance, and product longevity.

2. Crimp Integrity

Crimped connections are only reliable when executed precisely. IPC standards define what constitutes an acceptable crimp and how it must be validated.

Key indicators OEMs should look for include:

• Correct crimp height and compression

• Visible conductor brush

• No insulation captured in the wire barrel

• Proper engagement of insulation and conductor wings

• Pull-force testing that meets IPC requirements

Even minor deviations can lead to intermittent failures or open circuits in the field.

3. Cable Preparation and Shield Termination

Cable preparation errors often go unnoticed until systems fail under stress. IPC/WHMA-A-620 sets strict requirements for how cables are stripped, prepared, and terminated.

OEMs should confirm their CM adheres to:

• Defined strip-length tolerances

• Proper techniques to avoid jacket scoring or conductor damage

• Correct shield folding and grounding methods

• Controlled drain wire exposure limits

These practices are especially critical for EMI-sensitive, high-speed, or medical applications.

4. Labeling and Traceability

Clear labeling and traceability are essential for quality control, serviceability, and regulatory compliance.

A compliant cable and harness manufacturer should provide:

• Consistent, durable heat-shrink labels

• Serialization where required

• Barcode or QR-code tracking

• Documented inspector sign-offs tied to each build

Without robust traceability, identifying root causes during audits or field issues becomes significantly more difficult.

Testing Methods Required by IPC Standards

IPC/WHMA-A-620 does not stop at workmanship. It also mandates specific testing and inspection protocols.

OEMs should verify that their contract manufacturer performs and documents:

• Continuity testing across all applicable assemblies

• HiPot testing to confirm insulation integrity

• Pull-force testing to validate crimp strength

• Functional testing where applicable

• Visual inspections under magnification

Equally important is how results are recorded. Test documentation should be standardized, controlled, and easily retrievable.

How Sanbor Manufacturing Applies IPC Standards Globally

Sanbor Manufacturing applies IPC/WHMA-A-620 consistently across its global manufacturing footprint by maintaining:

• IPC/WHMA-A-620 trained and certified specialists

• Standardized global work instructions

• Unified inspection criteria across all facilities

• Digital quality records with full traceability

• Shared training programs across Asia, Europe, and the United States

This global alignment ensures OEMs receive the same workmanship quality regardless of manufacturing location, eliminating variability between regions.

Final Takeaway

IPC/WHMA-A-620 is more than a certification. It is a blueprint for reliability. OEMs that evaluate cable and wire harness workmanship through the lens of IPC are better equipped to qualify contract manufacturers, reduce risk, and ensure long-term product performance.

Sanbor Manufacturing adheres to Class 2 and Class 3 IPC standards across its worldwide factory network, helping OEMs achieve consistent, high-quality cable and wire harness production at scale.

Ready to get started? Call us at 610.530.8500, email sales@sanbormfg.com or connect through our quick online contact form.