IPC/WHMA-A-620 for buyers: how to use the standard in procurement

IPC/WHMA-A-620 provides acceptance criteria for workmanship on cables and harnesses: crimps, soldered terminations, splices, connectorisation, marking, shielding, wire wrap and related attributes. It tells inspectors and manufacturers how to judge whether a finished condition is acceptable, process indicator or defect for a stated product class. It is an acceptability document, not a complete design manual, not a substitute for your schematic, and not a certificate that automatically transfers to your end product.

Invoking “build to A-620” without a class, without a revision, or without resolving conflicts against your drawing leaves room for interpretation. The drawing and the purchase agreement still govern. Where your notes are silent, A-620 may fill gaps; where your notes are stricter or different, your notes should win if you say so explicitly.

The standard also does not replace component manufacturer crimp specifications. Terminal suppliers publish pull-force and crimp-height data for specific wire and die combinations. A-620 and manufacturer data work together; buyers should ask how both are used on the floor.

The standard defines product classes that reflect end-use criticality. Higher classes generally impose stricter acceptance criteria on the same attribute. Your equipment risk profile — general industrial machinery versus high-reliability infrastructure — should drive the class you call out, in agreement with your quality organisation and, where applicable, your end customer.

Do not default to the strictest class “to be safe” without understanding cost, yield and lead-time impact. Over-classing creates scrap on conditions that would not affect your field reliability, while under-classing creates false confidence when the application is demanding. Mismatch between class and actual need is one of the most expensive silent decisions in an RFQ.

If different assemblies on the same machine warrant different classes — for example a safety-critical PE link versus an internal low-voltage sensor lead — state class per part number rather than one blanket note for the whole programme.

State the standard designation, revision and class in drawing notes or in a referenced quality requirements document. Ambiguous phrases such as “IPC compliant” without A-620 and class help neither quoting nor inspection. Where your drawing conflicts with A-620, state the document hierarchy: for example “drawing notes take precedence; where silent, IPC/WHMA-A-620 Class X applies.”

For attributes the standard does not cover — customer-specific label content, unique electrical tests, special packaging — keep those requirements on the drawing or quality plan. Do not assume A-620 implies your barcode format or your hipot voltage.

Require that personnel performing acceptance are trained to the criteria you invoked, and ask how that training is maintained over time. You are evaluating process discipline and shared definitions, not collecting logos for a slide deck.

Ask which class they would propose if none is stated on your package, and why. Ask how they handle attributes not covered by A-620. Ask whether operators have acceptance criteria at the station or only at final inspection. Ask how defects are dispositioned, who can accept process indicators, and whether sample microsections or pull tests are used for crimp families on your bill of materials.

Ask to see example acceptance records from similar products — redacted if needed — so you understand format and depth before first article. Ask how engineering changes that affect workmanship criteria are communicated to the floor. Ask whether multiple manufacturing sites would use the same interpretation guide for your part numbers.

Treat third-party training certificates for individuals as supporting evidence for people capability, not as a substitute for part-specific first article inspection. A trained inspector still needs your cavity map, your length method and your label drawing. Casablanca Cable Company does not present standards names as marketing decoration; programme requirements are reviewed with you and then allocated to manufacturing partners whose processes can meet the called criteria.

When a shipment is questioned, reference specific clauses and photographs against the agreed class criteria. Vague “not to IPC” language helps neither party and slows corrective action. Equally, suppliers should cite clauses when defending borderline conditions rather than appealing to custom alone.

Periodic joint reviews of defect photos calibrate both sides. Subjective visual attributes — insulation damage thresholds, shield braid treatment, solder appearance — benefit from a shared gallery of accept and reject examples tied to your class. That gallery can live next to the FAI package.

For partner-manufactured programmes, insist that the commercial interface can retrieve clause-level disposition history for your lots. Diffused accountability across sites is a process failure, not an inevitable feature of partner models.

Calling out A-620 on the PO but never on the drawing leaves production uncertain which revision of which document applies after an ECO. Calling out Class 3 for everything then arguing about cost and scrap is predictable. Ignoring manufacturer crimp specs while citing only A-620 leaves pull-force disputes without a number.

Another frequent mistake is treating A-620 as proof of product safety certification for the finished equipment. Acceptability of harness workmanship is not the same as equipment conformity assessment. Keep those ownership lines clear in contracts and RFQs.

Finally, do not confuse “we have heard of A-620” with a controlled inspection plan. The standard becomes useful when class, revision, hierarchy and training are explicit and when your receiving team uses the same references as the build site.

Start with a short internal workshop: quality, design and procurement agree class per product family, hierarchy notes and which attributes need photo standards beyond the book. Update drawings or a quality requirements document in one controlled release rather than scattering notes across emails.

At RFQ, ask suppliers to confirm they can inspect to that package and to flag any notes they find ambiguous. Ambiguity discovered at quote is cheaper than ambiguity discovered at dock reject. Include A-620 class and revision in the RFQ checklist so it is not forgotten on the next spin.

After FAI, lock the interpretation extras — photo standards, measurement fixtures, any agreed deviations — into the approved package. Serial production should not reopen class philosophy every lot.