Surface finish selection can make or break a flex PCB design. Unlike rigid boards, flexible circuits face unique challenges: repeated bending stresses the solder joint interface, thin polyimide substrates demand gentler chemical processes, and tight bend radii expose finishes to mechanical fatigue. Our engineering team evaluates your application requirements — component types, operating environment, assembly method, expected lifetime — and recommends the optimal finish. We process all six major surface finish types in-house, with dedicated lines calibrated specifically for flex and rigid-flex substrates.
OSP or ENIG for smartphones, wearables, and tablets — balancing cost with fine-pitch solderability on high-density flex layouts.
ENIG for implantables and diagnostic equipment where long shelf life, flat pad surface, and corrosion resistance are non-negotiable.
ENIG or immersion tin for sensors, displays, and control modules operating in temperature extremes from -40°C to +150°C.
Immersion silver for low insertion loss on antenna feeds, RF front-ends, and millimeter-wave flex circuits.
ENIG with hard gold tabs for high-reliability connectors, wire bonding pads, and mission-critical avionics flex assemblies.
OSP or lead-free HASL for cost-sensitive LED flex strips where solderability matters more than long-term storage.
Our engineers review your Gerber files, BOM, and assembly requirements. We assess pad geometry, component pitch, operating environment, and expected shelf storage time.
Based on your specific needs, we recommend one or more finish options with a clear comparison of trade-offs: cost, flatness, solderability window, and reliability.
Flex panels undergo micro-etching and cleaning optimized for polyimide substrates. Surface roughness and copper condition are verified before plating.
Each finish runs on a dedicated production line with chemistry, temperature, and immersion times calibrated for flex PCB thickness and panel size.
XRF thickness measurement on every panel. Solderability testing per IPC J-STD-003. Cross-section analysis available for critical applications.
Our plating baths are tuned specifically for polyimide-based substrates. Rigid PCB parameters do not transfer directly to flex — we account for thinner copper, flexible base materials, and coverlay openings.
No outsourcing, no delays. ENIG, OSP, lead-free HASL, immersion silver, immersion tin, and hard gold — all processed under one roof with consistent quality control.
Our surface finish lines comply with IPC-4552 (ENIG), IPC-4553 (immersion silver), IPC-4554 (immersion tin), and J-STD-003 solderability standards.
Not sure which finish suits your design? Our application engineers provide free consultations with data-driven recommendations based on your exact use case.
Discover our complete range of flex PCB manufacturing and assembly services
