IPC/WHMA-A-620 Explained: Complete Guide to Cable & Wire Harness Standards

When I first started working with wire harness assemblies, the inspection criteria felt like a moving target. Every customer had different requirements, every inspector had different interpretations, and getting consistent quality across production runs was a constant battle. That changed when our facility adopted IPC/WHMA-A-620 as our baseline standard.

If you’re involved in cable and wire harness manufacturing, inspection, or procurement, understanding IPC/WHMA-A-620 isn’t optional anymore. It’s become the global language for what constitutes acceptable workmanship in our industry. This guide breaks down everything you need to know about this essential standard, from product classifications to certification requirements.

What is IPC/WHMA-A-620?

IPC/WHMA-A-620, officially titled “Requirements and Acceptance for Cable and Wire Harness Assemblies,” is the only industry-consensus standard for cable and wire harness fabrication and inspection. Developed jointly by IPC (Association Connecting Electronics Industries) and WHMA (Wire Harness Manufacturers Association), this standard defines materials, methods, tests, and acceptance criteria for producing cable and wire harness assemblies.

The standard covers acceptance criteria for:

• Crimped interconnections (stamped, formed, and machined contacts)
• Soldered terminations to terminals and connectors
• Mechanically secured connections
• Ultrasonic welded splices
• Insulation displacement connections (IDC)
• Cable and harness assembly requirements

What makes IPC/WHMA-A-620 particularly valuable is its visual approach. With over 700 full-color photographs and illustrations, the standard provides clear visual references for what constitutes target conditions, acceptable conditions, process indicators, and defects.

Brief History of IPC/WHMA-A-620

The standard has evolved significantly since its initial release:

The current revision, IPC/WHMA-A-620E, represents significant industry-requested changes including a completely reorganized chapter structure for improved usability.

IPC/WHMA-A-620 Document Structure

Understanding how the standard is organized helps you find specific criteria quickly. Revision E reorganized the document into 19 chapters:

This structure allows you to quickly locate specific acceptance criteria without searching through unrelated content.

Product Class Classifications

One of the most important concepts in IPC/WHMA-A-620 is the three-class product classification system. The class determines what level of workmanship is required for your specific application.

Class 1: General Electronic Products

Class 1 applies to products where the primary requirement is basic functionality of the completed assembly.

Characteristics:

• Shortest expected service life
• Cosmetic imperfections acceptable if function maintained
• Widest acceptance tolerances
• Most economical production approach

Typical Applications:

• Consumer electronics (toys, simple appliances)
• Non-critical industrial equipment
• Disposable or short-life products
• High-volume, low-cost assemblies

Class 2: Dedicated Service Electronic Products

Class 2 covers products requiring extended performance and longer operational life where uninterrupted service is desired but not absolutely critical.

Characteristics:

• Extended life expectancy
• Higher reliability requirements than Class 1
• Moderate acceptance tolerances
• Balance between quality and cost

Typical Applications:

• Communications equipment
• Computers and servers
• Industrial controls
• Medical equipment (non-life-support)
• Automotive (non-safety-critical)

Class 3: High-Performance/Harsh Environment Electronic Products

Class 3 represents the highest reliability level where continued performance or performance-on-demand is critical.

Characteristics:

• Highest reliability requirements
• Strictest acceptance tolerances
• Equipment downtime cannot be tolerated
• May operate in harsh environments

Typical Applications:

• Life support medical equipment
• Aerospace and defense systems
• Military applications
• Critical safety systems
• Space applications (with Space Addendum)

Class Comparison Summary

The product class must be agreed upon between the customer and manufacturer before production begins. This agreement drives all subsequent acceptance decisions.

Key Acceptance Criteria in IPC/WHMA-A-620

Let me walk through some of the most commonly referenced acceptance criteria that you’ll encounter in wire harness production.

Wire Preparation Requirements

Proper wire preparation is fundamental to reliable terminations. IPC/WHMA-A-620 specifies criteria for:

Strip Length: Must match terminal manufacturer specifications, typically with tolerances of ±1mm for most applications.

Strand Damage: The acceptable number of cut, nicked, or broken strands varies by class:

Insulation Damage: Cuts, nicks, or scrapes that expose conductor are defects for all classes. Discoloration from heat is acceptable if insulation properties are maintained.

Crimp Termination Criteria

Crimping is the most common termination method, and IPC/WHMA-A-620 provides extensive visual criteria:

Conductor Crimp Requirements:

• All strands captured in crimp barrel
• No strands outside the crimp area (bellmouth excluded)
• Conductor visible in inspection window (where applicable)
• No cracks in crimp barrel

Insulation Crimp Requirements:

• Insulation grip engages wire insulation
• Gap between conductor and insulation crimps within specification
• No insulation in conductor crimp area

Crimp Height: Must be within manufacturer’s specified tolerances. Cross-section analysis may be required for Class 3 qualification.

Soldered Termination Criteria

When solder terminations are used, IPC/WHMA-A-620 aligns with J-STD-001 requirements:

Solder Fill Requirements:

Common Defects:

• Cold solder joints (grainy, dull appearance)
• Insufficient wetting
• Solder bridges
• Exposed copper (insufficient tinning)
• Damaged insulation from heat

Shielding Requirements

Shield termination is critical for signal integrity in cable assemblies:

Braid Coverage: Minimum 85% optical coverage required for effective shielding (95% or higher for high-frequency applications).

Termination Methods:

• 360° termination preferred for Class 3
• Pigtail terminations acceptable with length limitations
• Solder sleeve terminations must show complete reflow

Read more IPC Standards:

MIL-PRF-38534: Hybrid Microcircuits Military Specification Guide for Engineers

MIL-PRF-31032: The Definitive Guide to Military-Grade PCB Requirements

MIL-PRF-19500: Military Semiconductor Device Specification Explained

MIL-PRF-123: High-Reliability Ceramic Capacitor Military Standard

MIL-I-46058CMIL-I-46058C: Military Conformal Coating Specification Complete Guide

MIL-HDBK-263: ESD Control Handbook & Implementation Guide

J-STD-075 Guide: PSL Classification for Passive Components & Assembly Process Limits

J-STD-035 Guide: Acoustic Microscopy for IC Package Inspection & Defect Detection

J-STD-033 Guide: MSD Handling, Floor Life, Baking & Dry Storage Requirements

J-STD-032 Explained: Ball Grid Array Ball Construction & Performance Specs

J-STD-027 Guide: Mechanical Outline Standard for Flip Chip & CSP Packages

J-STD-020 Guide: MSL Classification, Reflow Profiles & Moisture Sensitivity Testing

IPC/WHMA-A-620 Explained: Complete Guide to Cable & Wire Harness Standards

IPC-SG-141: Complete Guide to S-Glass Fabric Specifications for PCB Laminates

IPC-QF-143: Complete Guide to Quartz Fabric Specifications for RF/Microwave PCB Laminates

IPC/WHMA-A-620 vs Related Standards

Understanding how IPC/WHMA-A-620 relates to other IPC standards helps you apply the right criteria for your products.

IPC/WHMA-A-620 vs IPC-A-610

This is the most common point of confusion in electronics manufacturing:

Key Point: If your product includes both a wire harness and PCB assembly, you may need to reference both standards. Wire-to-PCB connections typically fall under IPC-A-610, while the harness itself falls under IPC/WHMA-A-620.

IPC/WHMA-A-620 vs IPC-D-620

Think of it this way: IPC-D-620 tells you how to design a harness; IPC/WHMA-A-620 tells you how to inspect whether it was built correctly.

IPC/WHMA-A-620 Certification Programs

IPC offers three levels of certification for individuals working with the A-620 standard:

Certified IPC Specialist (CIS)

Target Audience: Assembly operators, inspectors, quality technicians, production engineers

Requirements:

• Complete training modules (lecture and optional hands-on)
• Pass open-book examination (70% minimum)
• Valid for 2 years

What You’ll Learn:

• Interpret acceptance criteria for all three classes
• Identify target, acceptable, process indicator, and defect conditions
• Apply criteria to real-world inspection situations

Certified Standards Expert (CSE)

Target Audience: Quality engineers, manufacturing engineers, technical supervisors

Requirements:

• Prior electronics industry experience recommended
• Pass open-book and closed-book examinations (80% minimum)
• Valid for 2 years

Role: Serve as subject matter expert for standards interpretation and conflict resolution without requirement to train others.

Certified IPC Trainer (CIT)

Target Audience: Training managers, quality managers, internal trainers

Requirements:

• Pass open-book and closed-book examinations (80% minimum)
• Train minimum 10 students during certification period
• Valid for 2 years

Capability: Authorized to deliver CIS training and certification within their organization or as external trainers.

Certification Comparison

Space and Military Addendums

For aerospace and defense applications, additional addendums are available:

IPC/WHMA-A-620E-S (Space Addendum): Provides additional requirements beyond Class 3 for assemblies that must survive space environments. Cannot be used as standalone document.

IPC/WHMA-A-620E-M (Military Addendum): Additional requirements for military applications, incorporating relevant MIL-SPEC content.

Implementing IPC/WHMA-A-620 in Your Facility

Based on my experience implementing this standard across multiple facilities, here are practical recommendations:

Start with Training: Invest in CIS certification for all inspection personnel and production operators. Consistent interpretation of criteria is essential.

Establish Class Agreement: Document the product class in customer contracts and work instructions before production begins. This prevents disputes later.

Create Visual Standards: Develop internal workmanship standards with photographs showing acceptable and defect conditions specific to your products.

Calibrate Inspection: Conduct regular inspector correlation studies to ensure consistent accept/reject decisions across shifts and locations.

Document Everything: For Class 2 and Class 3 products, maintain complete traceability records including material certifications, process parameters, and inspection results.

Useful Resources for Wire Harness Engineers

Official IPC Publications

• IPC/WHMA-A-620E Standard: shop.ipc.org/ipcwhma-a-620
• IPC-HDBK-620: Handbook and Guide for IPC/WHMA-A-620
• IPC/WHMA-A-620E-S: Space Electronics Hardware Addendum
• IPC-D-620A: Design Requirements for Cable and Wire Harness

Related Standards

• IPC J-STD-001: Requirements for Soldered Electrical and Electronic Assemblies
• IPC-A-610: Acceptability of Electronic Assemblies
• NASA-STD-8739.4: Crimping, Interconnecting Cables, Harnesses, and Wiring

Training and Certification

• IPC Certification Portal: www.ipc.org/certification
• IPC Document Revision Table: electronics.org/document-revision-table
• WHMA (Wire Harness Manufacturers Association): www.whma.org

Industry Organizations

• IPC (Association Connecting Electronics Industries): www.ipc.org
• SAE International: Aerospace wiring standards (AS50881, AS22759)

Frequently Asked Questions About IPC/WHMA-A-620

What is the current revision of IPC/WHMA-A-620?

The current revision is IPC/WHMA-A-620E, released in October 2022. This revision introduced a new chapter numbering system, aligned soldering requirements with IPC J-STD-001, revised the Circular Mill Area (CMA) tables, and updated terms and definitions in Appendix A. Earlier revisions (D, C, B, A) are still valid if specified in contracts, but new programs should reference Revision E.

How long is IPC/WHMA-A-620 certification valid?

All IPC/WHMA-A-620 certifications (CIS, CSE, and CIT) are valid for two years from the date of certification. Recertification requires completing an updated training course and passing the examination again. For CIT certification, the trainer must also have certified at least 10 students during their certification period to be eligible for recertification.

Can IPC/WHMA-A-620 be used as a standalone purchasing document?

Yes, IPC/WHMA-A-620 can be used as a standalone document for purchasing cable and wire harness assemblies. However, the standard does not specify inspection frequency or limits on repairs and rework. These parameters should be established separately through a statistical process control plan or customer specification. The product class must also be agreed upon between buyer and seller.

What is the difference between a Process Indicator and a Defect?

A Process Indicator is a condition that does not affect the form, fit, or function of the assembly but indicates the process could be improved. Process indicators are not counted as defects and do not require rejection or rework. A Defect is a condition that does not meet acceptance criteria and must be either reworked, repaired, or rejected. The classification of specific conditions as process indicators or defects varies by product class.

Do I need both IPC/WHMA-A-620 and IPC-A-610 for my facility?

It depends on your products. If you manufacture wire harnesses or cable assemblies only, IPC/WHMA-A-620 is sufficient. If you manufacture PCB assemblies only, IPC-A-610 is appropriate. If your products include both wire harnesses and PCB assemblies (which is common), you’ll benefit from having both standards. The interface between harness and PCB should be clearly defined in your documentation to specify which standard applies to each connection point.

Conclusion

IPC/WHMA-A-620 has established itself as the definitive standard for cable and wire harness acceptance criteria since its introduction in 2002. For engineers, inspectors, and quality professionals working with wire harness assemblies, understanding this standard is fundamental to producing reliable products and communicating effectively with customers and suppliers.

The three-class system provides flexibility to match quality requirements to application needs, from consumer products to life-critical aerospace systems. Combined with the certification programs that ensure consistent interpretation across the industry, IPC/WHMA-A-620 provides a common framework that benefits everyone in the supply chain.

Whether you’re implementing the standard for the first time or updating to Revision E, the investment in training and process development pays dividends in reduced disputes, improved first-pass yields, and stronger customer relationships. The standard continues to evolve with industry needs, and staying current with revisions ensures your facility maintains its competitive edge in wire harness manufacturing.