IPC/WHMA-A-620 is the industry standard for cable and wire harness workmanship — the document auditors reference when visiting our factory, the acceptance criteria quality engineers use during incoming inspection, and the benchmark every customer RFQ mentions. We deliver ipc whma a 620 certified cable harness built strictly to this specification. First published in 2002 as a joint effort between IPC and the Wiring Harness Manufacturers Association, now in its current revision. We run production to IPC/WHMA-A-620 at Class 2 by default and Class 3 on request. Operators are CIS certified; in-house CIT trainers maintain certification across the workforce. This page covers what the standard means and how we comply. For our full certification scope, see the quality and certifications page.
What IPC/WHMA-A-620 Covers
The standard is the cable and wire harness equivalent of IPC-A-610 (which covers PCB assemblies). It defines visual acceptance criteria, process controls, and inspection methods across the full scope of harness manufacturing:
- Wire preparation and stripping — strip length tolerance, nick and cut limits, conductor strand preservation.
- Crimping — terminal crimps (open barrel, closed barrel, F-crimp), IDC (Insulation Displacement Contact), and pull force acceptance criteria.
- Soldering — hand soldering, solder pot dipping, and wave soldering acceptance. Wetting, fillet shape, and contamination criteria.
- Splicing — butt splice, parallel splice, and stepped splices. Mechanical and electrical requirements.
- Heat-shrink sleeving — shrinkage quality, adhesive flow (for adhesive-lined tubing), end conditions.
- Harness assembly — jig board routing, tying techniques, cable tie tension, lacing criteria.
- Overmolding and potting — adhesion, void criteria, cosmetic acceptability. See our overmolded cable page for process detail.
- Electrical testing — continuity, hi-pot (dielectric withstand), insulation resistance.
- Protective finishes — sleeving, braiding, spiral wrap, convoluted tubing application.
Each process area has specific acceptance criteria, defect examples with photographs, and measurement methods. The standard runs about 500 pages in current revision — operators reference the sections relevant to their specific tasks.
The Three Classes — When Each Applies
Class is the single most important decision in IPC/WHMA-A-620 specification. It determines which acceptance criteria apply and which defects are acceptable versus rejectable:
| Class | Definition | Typical Applications |
|---|---|---|
| Class 1 — General Electronic Products | Items where function is the main requirement. Short to medium service life. | Toys, consumer gifts, short-life consumer electronics |
| Class 2 — Dedicated Service Electronic Products | Extended service life where continuous performance is desired. Short outages tolerable. | Industrial equipment, commercial electronics, standard automotive body, telecom infrastructure |
| Class 3 — High Performance / Harsh Environment | Continued performance or performance-on-demand is critical. Downtime cannot be tolerated. End-use environment may be harsh. | Medical life-support, aerospace, military, automotive safety-critical (airbag, brake, ADAS), space hardware |
Class 2 is our default. Class 3 is specified on medical, aerospace, and safety-critical automotive programs, and runs roughly 30-40% higher inspection time per piece. Class 1 is rare in our mix — most consumer programs specify Class 2 despite the “consumer” label.
Class 2 vs Class 3 — What Actually Changes
The difference between classes is mostly about tighter tolerances and tighter defect acceptability. Specific examples:
- Strip length tolerance. Class 2 allows a wider range; Class 3 tightens the window. A strip that’s slightly too long may pass Class 2 but fail Class 3.
- Conductor nicks and cuts. Class 2 permits some minor nicks if strand count meets minimum. Class 3 is stricter — damaged strands count against acceptance.
- Crimp pull force. Both classes require pull testing, but Class 3 requires tighter statistical control and more frequent sampling.
- Solder joint appearance. Class 2 accepts slightly less-than-ideal fillets. Class 3 requires textbook wetting and smooth surface appearance.
- Overmold voids and flash. Minor cosmetic variation acceptable in Class 2. Class 3 rejects more aggressively.
- Test coverage. Class 2 typically requires 100% continuity plus sampled other tests. Class 3 commonly requires 100% on multiple test types plus environmental samples.
Class 3 doesn’t mean “better product always.” It means tighter quality controls that make sense when failure consequences are severe. For consumer USB cable, Class 2 is correct; using Class 3 adds cost without real reliability gain. For an ICU ventilator cable, Class 3 is the only appropriate choice.
Our IPC Certification Program
- CIT (Certified IPC Trainer). In-house trainers certified by IPC to train and certify operators. We maintain multiple CITs for IPC/WHMA-A-620 plus related standards (J-STD-001 for soldering).
- CIS (Certified IPC Specialist). Production operators certified by our CITs. Every operator performing IPC-scope work holds current CIS certification in relevant sections.
- Biennial recertification. IPC requires CIS and CIT certifications renewed every 2 years. Our training schedule includes regular recert cycles, and we don’t allow certification lapses on production floor assignments.
- Section-specific certification. Operators certify on specific IPC/WHMA-A-620 sections matching their job function — a crimper operator holds certification on crimp-related sections, not the entire standard.
Certification records are maintained in our training database and available for audit. Customer auditors frequently verify operator certification status during facility visits.
Related Standards We Also Reference
IPC/WHMA-A-620 doesn’t exist in isolation. Depending on customer requirement, programs reference these connected standards:
- IPC-A-610 — Acceptability of Electronic Assemblies. Applies to PCB-mounted components, separate from harness work but often referenced together when box-build includes both.
- IPC J-STD-001 — Requirements for Soldered Electrical and Electronic Assemblies. Covers the soldering process itself in detail. Class 2 default, Class 3 available.
- IPC-7711/7721 — Rework, Modification, and Repair. Relevant for field-repair and rework operations.
- AS9100 — Aerospace quality management. Pairs with IPC Class 3 for aerospace programs. Our aerospace programs run through qualified AS9100 partner facilities.
- VDA 6.3 — Automotive process audit. Typically paired with IATF 16949 for Tier-1 automotive work. IPC Class 2 or 3 depending on program.
- ISO 13485 — Medical device quality. Commonly paired with IPC Class 3. See our medical cable assembly page for ISO 13485 detail.
How Customer Audits Work
Customers routinely audit our IPC/WHMA-A-620 compliance. Typical audit sequence:
- Documentation review. Training records, CIT and CIS certificates, control plans, defect-handling procedures.
- Floor walk. Production area observation, operator certification verification, equipment calibration status check.
- Process sampling. Auditor selects random finished units and compares against IPC/WHMA-A-620 visual criteria for the specified class.
- Test station review. Electrical test equipment calibration, pull tester calibration, crimp micrograph verification.
- Nonconforming material handling. How defects are identified, segregated, documented, and dispositioned.
- Corrective action follow-up. Any findings from previous audits — closed or still open?
Medical, aerospace, and Tier-1 automotive customers usually audit annually. New customer programs include an initial audit before first article approval. We also work with second-party audits (Tier-1 auditing us on behalf of their OEM) and third-party certification bodies (Intertek, SGS) when independent verification is required.
Why SZFRS for IPC/WHMA-A-620 Work
Multiple in-house CITs. Redundancy matters — losing a single CIT shouldn’t stop training or certification activity. We maintain multiple CITs covering IPC/WHMA-A-620, J-STD-001, and IPC-A-610.
100% CIS-certified operator base. No operator works on IPC-scope production without current section-relevant CIS. Audit-ready at any time.
Class 2 default, Class 3 on request. Transitions between classes handled by changing the inspection procedure and tolerance set, not changing the factory setup. We’ve run Class 3 programs through the same production cells as Class 2 — the operators, equipment, and process remain the same, but inspection tightens.
Calibrated test and inspection equipment. Pull testers, micrographs for crimp cross-sections, electrical test sets all calibrated on documented intervals. Calibration records maintained per ISO 9001 and referenced during audits.
Documentation in Chinese and English. Training materials and procedures maintained in both languages so that international customer auditors can review work instructions in English while local operators reference Chinese.
Transparent nonconformance handling. Defects caught during in-process or final inspection are documented, segregated, and reviewed through a Material Review Board process. No shipping-despite-defects cultures.
Frequently Asked Questions
Do you provide IPC/WHMA-A-620 certificates with shipments?
Yes. Certificate of Conformance citing the applicable IPC/WHMA-A-620 revision and class is standard with every shipment. Operator certification records available on request. First article inspection reports include specific IPC/WHMA-A-620 section references for each inspection point.
Can I specify Class 2 for most of my harness and Class 3 for critical sub-assemblies?
Yes. Mixed-class builds are common. A harness might have Class 2 for general circuits and Class 3 for safety-critical branches like airbag or brake signals. Tell us which sections need Class 3, and we adjust inspection accordingly. Per-piece cost increases proportionally to Class 3 coverage.
How do I know if my product needs Class 2 or Class 3?
Industry convention: consumer, industrial, and standard commercial — Class 2. Medical, aerospace, space, defense, and automotive safety-critical — Class 3. For edge cases (premium consumer, high-reliability industrial), check your OEM customer’s specification or your own internal reliability target. When in doubt, ask your quality team — they’ll have a position on this.
Do your CITs and CISes have current certifications?
Yes. All production operators hold current CIS certifications in sections relevant to their work. Our CITs hold current trainer certifications from IPC. Expiration dates tracked in our training database. Auditors can verify individual operator certifications during facility visits.
Can you do Class 3 soldering per J-STD-001 along with Class 3 IPC/WHMA-A-620?
Yes. Our soldering operators hold J-STD-001 CIS certifications alongside IPC/WHMA-A-620. For programs requiring Class 3 solder workmanship (often medical and aerospace), both standards apply together at Class 3.
What happens if your factory fails my IPC audit?
Audit findings generate a Corrective Action Request (CAR). We investigate root cause, implement corrective action, and verify through follow-up audit or documentation review. Major nonconformance may pause production until resolved; minor findings typically close within 30-60 days. We treat audit findings as improvement opportunities rather than adversarial events — the sooner issues surface, the sooner they’re fixed.
Do you accept customer-specific workmanship standards beyond IPC/WHMA-A-620?
Yes. Many OEMs maintain internal workmanship specifications that supplement or replace IPC/WHMA-A-620 — GMW, Ford SQD, Boeing D6-1276, Nasa NASA-STD-8739.4. We accept and train to these per program. Customer-specific standards typically add to Class 3 IPC baseline rather than replacing it.
Can non-English speakers understand your IPC training materials?
Our operators train in Chinese with IPC/WHMA-A-620 terminology cross-referenced to English. Training materials, work instructions, and reference photos are maintained bilingually. Customer audit documents provided in English by default.
Related Pages and Services
- Quality & Certifications — full certification scope including ISO 9001, IATF 16949, ISO 13485, and others.
- Custom Manufacturing — overview of value-added services.
- Cable Assembly — cable assembly work runs to IPC/WHMA-A-620 by default.
- Wire Harness — wire harness production follows IPC/WHMA-A-620 workmanship.
- Medical Cable Assembly — Class 3 IPC plus ISO 13485 for medical programs.
- Automotive Wire Harness — Class 2 baseline, Class 3 for safety-critical.
Ready to Discuss IPC WHMA A 620 certified cable harness Requirements?
Tell us the target class, specific standard revisions required, and any customer-specific supplements. We’ll confirm compliance capability, certification coverage, and documentation scope before quote. Audit visits welcome — we schedule buyers and quality auditors regularly.