EPIG describes an electroless palladium and immersion gold finish without the nickel layer present in ENEPIG. When a project considers a nickel-free finish, evaluate the complete conductor and joining system rather than assuming that removing one layer automatically solves every electrical or assembly issue.
State why a nickel-free structure is proposed
Identify the specific RF, high-speed, fine-feature or joining requirement that motivates the choice. Compare the proposed finish in the actual channel or assembly model. Keep the expected benefit measurable so it can be checked against a representative board.
Confirm the supplier’s exact process
Finish names can hide differences in process chemistry, layer control and qualified application range. Ask for the proposed construction, acceptance specification and inspection method. Do not convert a supplier’s example into a general manufacturing limit for every fabricator.
Validate the downstream connection
Review soldering, bonding, storage and handling using the materials and geometry of the actual product. Agree which test vehicle or first article will demonstrate suitability. Consider both initial performance and the required environmental or lifetime evaluation.
Keep alternates explicit
An alternate finish changes the surface stack and may change processing assumptions. List which substitutions are permitted and what evidence is needed to approve them. Update the fabrication drawing and assembly requirements together if the selected finish changes.
Release checklist
- Define the performance reason for the finish choice.
- Approve the exact layer system and acceptance method.
- Test representative connection geometries.
- Record permitted alternatives and change approval.