TWS Earphones — Parylene Replaced at Scale
Client Context
A large consumer electronics OEM manufacturing TWS earphones across multiple factories in China and Vietnam had qualified parylene as their protection standard. Scrap rates had plateaued at 3% and were not improving despite process optimisation efforts. Reworkability was a persistent issue — parylene-coated components could not be repaired post-coating without stripping, adding cost and complexity to the production line.
The Challenge
The OEM needed a PFAS-free replacement for parylene that could be qualified across multiple factories simultaneously, deliver better yield performance, eliminate the scrap plateau, and maintain full reworkability — all without capital expenditure or line reconfiguration.
The Outcome
P2i's Barrier Coating was qualified as Plan of Record across all earphone and TWS device lines at the OEM's China and Vietnam factories. First-pass yield reached 99.97%. Scrap was reduced from a 3% plateau to zero. Masking requirements were eliminated. Full reworkability was maintained post-coating. The transition from parylene was completed without production interruption.
Parylene has long been the default protection choice for complex consumer electronics requiring reliable PCBA barrier performance. But its limitations at production scale are well understood: it cannot be reworked, it requires vacuum deposition equipment, and it generates scrap when coverage is inconsistent across complex geometries.
For this OEM, those limitations had crystallised into a measurable production problem. A 3% scrap plateau was costing significant material and assembly value per production run. The inability to rework coated components meant defective units were written off rather than recovered. And the regulatory direction away from PFAS chemistries was adding compliance pressure on top of the existing yield challenge.
P2i was engaged to qualify a replacement process that could address all three issues simultaneously. The engineering team reviewed the device architecture — complex flexible PCBAs, dense connector arrays, and small-aperture acoustic components — and recommended Barrier Coating as the protection path.
Qualification was conducted in parallel across the OEM's China and Vietnam factories, using P2i's factory-in-factory deployment model. Coating equipment was placed directly into each production facility on a free-of-charge basis, with a per-unit commercial model that aligned cost directly with production volume. P2i engineers were embedded on-site through the qualification and ramp phases.
The results exceeded the OEM's targets. First-pass yield reached 99.97% — eliminating the scrap plateau entirely. Masking, which had been required for certain connector geometries under the parylene process, was eliminated. Post-coating rework was fully supported. The PFAS-free process met all regulatory requirements without chemistry compromise.
The deployment is now sustained across all factories at full production volume.
