ENEPIG PCB: Soldering, Wire Bonding & Finish Review

For a soldering-only board, first establish whether ENIG or another qualified finish meets the requirements. ENEPIG deserves specific review when the board combines soldering and wire bonding, or a customer specification calls for the three-layer finish. State which pads serve each connection method.

Identify the wire material, diameter and bonding method for bonding applications. A supplier process description cannot substitute for trials with the actual board and assembly route. Request a feasibility review before treating every visible gold pad as interchangeable.

The nickel, palladium and gold have separate functions and measurement requirements. Record each layer against the agreed drawing and specification revision. Palladium processes may produce essentially pure palladium or phosphorus-containing deposits; the approved chemistry and process window matter.

Use the thickness workbench for one layer at a time. It converts the units and summarizes three entered readings without deciding acceptance. Preserve the raw report, measurement locations and method rather than combining nickel, palladium and gold into one average.

Define how bonding pads will be protected during printing, soldering, cleaning, handling and storage. The surface that reaches the bonder can differ from the freshly finished bare board. Include the planned thermal sequence and any cleaning restrictions in the request.

An IPC-hosted investigation documents bonding and pad-lift challenges on ENEPIG boards. The practical lesson is to qualify the complete route. A good coating thickness result alone does not demonstrate an acceptable bond, and a visually clean surface does not establish chemical cleanliness.

Send controlled fabrication data, an annotated pad map and the intended PCB assembly flow. Identify any wire-bond trials, sample records or lot documentation you need. Ask PCBSync to confirm the offered scope, unresolved requirements and acceptance basis in writing.

Keep qualification evidence distinct from routine shipment records. A representative bonding trial answers a different question from an incoming thickness report. Agree which evidence belongs with every lot and which must be repeated after a material, finish process or assembly change.