IPC/WHMA-A-620 is the industry’s only consensus standard covering requirements and acceptance for cable and wire harness assemblies. Developed by IPC (the Global Electronics Association) and WHMA (the Wire Harness Manufacturers Association), it gives buyers and manufacturers a shared definition of wire harness assembly quality.
The standard defines materials, methods, and acceptance criteria by application class. The IPC class you specify on your purchase order drives every inspection decision your manufacturer makes. Getting it wrong adds cost or invites failure. Getting the class right protects your program.
What is IPC/WHMA-A-620?
IPC/WHMA-A-620 provides a common language for cable and wire harness manufacturing. IPC and WHMA update the IPC WHMA A-620 standard periodically. Verify the revision before specifying it on a drawing package.
The standard and its current edition
First published in 2002, the IPC/WHMA-A-620 standard (often shortened to A-620) establishes workmanship requirements and inspection criteria. Manufacturers and buyers use both to align quality expectations before production begins.
Process control rules govern how those criteria apply throughout production. The current edition, IPC/WHMA-A-620F, released in October 2025, supersedes Revision E from 2022.
What the standard covers
As the governing standard for cable and wire harness manufacturing, IPC/WHMA-A-620 sets requirements and acceptance criteria across every stage of production. Coverage includes:
- Wire preparation: strand damage limits, conductor deformation, and stripping requirements by class
- Terminations: soldered connections per IPC J-STD-001 and crimped terminations with class-specific acceptance limits
- Connectorization: hardware mounting, connector integrity, and marking criteria
- Assembly: protective coverings, securing methods, bend radius, and strain relief requirements
- Testing: electrical and mechanical test methods, visual inspection criteria, and documentation
Why Chapter One matters
Chapter One contains requirements that govern the rest of the sections. A supplier who executes correct terminations but uses uncalibrated tooling or unqualified inspectors is non-conformant under Chapter One, regardless of how the joints look. Buyers who omit Chapter One requirements from their purchase orders lose the ability to enforce those controls at audit.
- Section 1.10 sets personnel proficiency standards: operators and inspectors must demonstrate competency before working on conforming products.
- Section 1.12 defines inspection methodology, including minimum illumination levels and magnification requirements for wire connection review.
- Sections 1.15 and 1.6 cover tool calibration and process control methodology, respectively.
The Three Quality Classes
IPC/WHMA-A-620 defines three classes, each matched to a product’s application and service requirements. Every workmanship criterion in the standard carries one of three condition classifications: Acceptable, Defect, or Process Indicator.
Across classes 1 to 3, what counts as acceptable may become a defect. Strand nicking during wire stripping illustrates the gap. From Class 1 to Class 3, a minor nick that passes at one level becomes rejectable at the other. Conductor integrity demands are simply higher at Class 3.
Class 1: General electronic products
Class 1 covers general electronic products where the function is the primary requirement. Cosmetic imperfections are acceptable as long as the assembly works. Products with short service lives or replaceable components typically fall into Class 1.
Class 2: Dedicated service for electronic products
Class 2 is the most common specification for industrial and commercial programs. Programs at this level require extended service life and continued performance but tolerate minor cosmetic variations.
Buyers frequently specify industrial controls and automotive electrical harnesses as Class 2. Most commercial programs default to Class 2 when no class appears in the drawing package.
Class 3: High-performance/harsh environment products
Class 3 requires the highest workmanship standards. IPC WHMA-A-620 Class 3 sets acceptance criteria that leave no tolerance for equipment downtime. Aerospace systems and medical life-support equipment fall under Class 3. The manufacturer must demonstrate that the process reliably produces a conforming product, not just that operators know the standard.
| Class 1 | Class 2 | Class 3 | |
|---|---|---|---|
| Typical application | Consumer goods, short service life. | Industrial controls, automotive harnesses. | Aerospace, medical life support. |
| Workmanship standard | Function is the primary requirement. | Extended life, continued performance. | Performance on demand, no downtime. |
| Cosmetic variation | Acceptable. | Minor variation tolerated. | Minimal tolerance. |
| Process control | No formal requirement. | Documented processes recommended. | Documented system required. |
| Default status | Rarely the default. | Most commercial programs default here. | Must be specified explicitly. |
Specifying the class before the first article inspection prevents disputes later. You bear the ultimate responsibility for identifying the class. If the drawing package doesn’t specify one, the manufacturer may assign it. The class 2 vs. class 3 decision belongs in the buyer’s engineering team before the purchase order goes out. Negotiating it at the inspection table adds cost and delay.
What IPC/WHMA-A-620 Covers
Every section of IPC/WHMA-A-620 defines three condition categories:
- Acceptable
- Defect
- Process Indicator
A Defect in Class 3 carries a mandatory disposition requirement that doesn’t apply at Class 1. Quality management for wire harness programs depends on process control methodology, not visual inspection alone.
The standard spans 20 chapters covering every cable and harness assembly activity, with class-specific acceptance limits throughout.
Process control is the mechanism that makes the standard work in practice. IPC/WHMA-A-620 requires Class 3 manufacturers to maintain a documented process control system that identifies which variables affect product quality.
Tool calibration intervals and operator proficiency records fall within the scope of that system. Kitting practices and error tracking require documented controls. An auditor reviewing a Class 3 program will ask how the manufacturer knows the process consistently produces an acceptable product. Identifying a defect after the fact isn’t enough.
Wire preparation and terminations
Wire stripping requirements define allowable strand damage and conductor deformation by class. Crimp termination criteria cover crimp height and insulation support with class-specific acceptance limits. Acceptance limits for bellmouth formation also vary by class.
Pull-force requirements by wire gauge appear in Section 19.4. For a 24 AWG conductor, the minimum pull force typically falls in a single-digit pound range. Your drawing and terminal type determine the exact applicable value. Soldered terminations comply with the IPC J-STD-001 criteria for wetting quality and post-solder damage to wire insulation.
Assembly and securing
Connectorization requirements in Section 9.0 cover hardware mounting and connector integrity. Strain relief protects terminations from mechanical stress at connector exits and is mandatory for Class 2 and Class 3 programs. Section 16.0 defines protective coverings, including braiding and sleeving. Bend radius requirements appear in Section 14.0 and vary by conductor type.
Testing and inspection
Section 19.0 defines both electrical and mechanical test methods. Electrical tests cover continuity and insulation resistance. Mechanical tests include pull force and crimp height measurement. IPC/WHMA-A-620 distinguishes two inspection types.
Process verification inspection confirms that a process remains under control during production. End-item inspection evaluates the finished assembly against acceptance criteria. The visual inspection in Section 1.12 applies to end-item review and specifies magnification requirements and lighting conditions for each connection type.
Objective evidence from both inspection types must accompany Class 2 and Class 3 deliveries.
IPC/WHMA-A-620 Certification vs. Staff Training
IPC/WHMA-A-620 certification and staff training are not the same qualification. A manufacturer may claim compliance without holding certified IPC personnel on staff. For buyers specifying Class 2 or Class 3 programs, that distinction matters at audit.
The IPC WHMA A-620 certification structure has three levels. Certified IPC Specialists (CIS) are operators and inspectors who apply the standard during production. Certified IPC Trainers (CITs) train and certify CIS personnel. Certified Standards Experts (CSE) hold the deepest knowledge of the standard and train CIT-level personnel.
| Credential | Role | Scope | Validity |
|---|---|---|---|
| CIS (Certified IPC Specialist) | Operator or inspector | Applies the standard on the production floor | 2 years |
| CIT (Certified IPC Trainer) | Trainer | Trains and certifies CIS personnel | Recertifies on the new standard revision |
| CSE (Certified Standards Expert) | Standards authority | Trains CIT-level personnel | Recertifies on the new standard revision |
CIS certification is valid for two years. After that period, recertification reflects any revisions to the standard. When you audit a supplier, ask for current CIS credentials for the operators assigned to your program. A company-level compliance declaration doesn’t confirm that certified IPC specialists are actively working on your build.
For Class 2 programs, trained personnel with documented processes may satisfy many buyer requirements. Class 3 programs require certified IPC specialists on staff and a fully documented process control system. Knowing how to implement its requirements at the production level determines Class 3 compliance under audit conditions. Passing an exam alone doesn’t satisfy Class 3 process control requirements.
IPC specialists trained to the current revision of the standard apply the standard more accurately. When the IPC WHMA-A-620 certification standard changes, knowledge gaps emerge among teams trained on earlier revisions. Buyers running Class 3 programs should ask suppliers when their CIS credentials were issued and whether they are valid for the current revision.
How to Specify IPC/WHMA-A-620 in Your Purchase Order
IPC/WHMA-A-620 can serve as a stand-alone purchasing document for wire harness and cable assemblies. Referencing it gives you enforceable acceptance criteria and a shared inspection language with any supplier. Without it, quality expectations stay subjective until something fails.
Your purchase order needs the full standard designation and the product class. Any class-specific deviations from your engineering specification belong there, too, before you issue the order.
Include the following in your purchase order or drawing notes:
- Full standard designation: IPC/WHMA-A-620F, or the revision in effect per your contract
- Product class: 1, 2, or 3
- Inspection evidence at delivery: pull-force test records or first-article inspection results
- Class-specific deviations: any permitted by your engineering specification
Buyers meeting customer requirements from downstream contracts should verify the purchase-order class matches the end-use application’s actual demands. Many programs receive a Class 2 purchase order when the harness supports a function that demands Class 3 reliability. The cost appears at inspection, not at the quoting stage.
When a purchase order specifies no class and the manufacturer assigns one, that choice may not match your application requirements. A cable and wire harness manufacturing supplier operating at Class 2 by default won’t apply Class 3 process control. The depth of documentation a customer audit requires won’t be there either. Specifying the class explicitly removes that ambiguity from the start.
Request objective evidence of compliance from your supplier, not a self-declaration. Test records and certificates of conformance must reference the specific standard and class. Suppliers build assemblies consistently when the drawing package leaves no ambiguity about which class applies and what evidence must accompany delivery.
How Cloom Tech Meets IPC/WHMA-A-620
Cloom Tech holds IPC/WHMA-A-620 certification and manufactures custom wire harnesses directly from your drawings and specifications.
Our production process builds quality in from the start rather than adding it at final inspection. All programs meet ISO 9001, IATF 16949, and IPC/WHMA-A-620 manufacturing standards, with full traceability through delivery.
We build Class 1 through Class 3 programs. Supply programs for Honda, Honeywell, Mahle, and GEELY demand consistent quality and documented processes. Every harness we manufacture ships to the same documented standard that those programs require.
Need a custom wire harness built to IPC/WHMA-A-620 standards? Get a free quote here.
IPC/WHMA-A-620 Explained FAQs
What is the difference between IPC/WHMA-A-620 Class 2 and Class 3?
Class 2 and Class 3 differ in workmanship strictness, documentation depth, and process control requirements. Class 2 requires extended service life and continued performance, with minor cosmetic variation tolerated.
Class 3 prohibits equipment downtime and requires the manufacturer to demonstrate process control, not just workmanship knowledge. A condition acceptable under Class 2 may be a rejectable defect in Class 3, particularly for crimped terminations and connector assembly.
How do I verify my supplier is IPC/WHMA-A-620 compliant?
Start by requesting current CIS credentials for operators and inspectors on your program. Follow that with a certificate of conformance referencing the class and revision.
Then request objective evidence from production: pull-force records and continuity test logs. A supplier who can’t provide all three items hasn’t demonstrated compliance. Certified IPC specialists must be on staff, not just referenced in a quality manual.
Do I need Class 3 for automotive wire harnesses?
Not always. Most automotive electrical harnesses carry a Class 2 rating, which specifies continued performance under typical operating conditions. Class 3 applies when the harness supports a safety function where failure cannot be tolerated.
Specify the class based on the end-use function, not the industry. Automotive wire harness and cable assembly programs vary widely in reliability requirements, and the drawing package should reflect the application’s actual demands.
What is a pull-force test in wire harness inspection?
A pull-force test applies controlled tension to a crimped termination to verify the mechanical bond between conductor and terminal. IPC/WHMA-A-620 Table 19-8 lists minimum pull-force values by wire gauge.
A termination that passes visual inspection may still fail the pull-force test if crimp height falls outside the accepted range. Pull-force testing is non-destructive when the applied load stays within the specified limit. Class 3 programs require pull-force data from each production run as objective evidence of quality control.
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