OSP (Organic Solderability Preservative

OSP is an eco-friendly, ultra-low-cost organic surface protection process. It forms a thin, uniform organic protective film on the bare copper surface to isolate air and prevent copper oxidation. The film layer will volatilize during soldering, exposing pure copper for welding. It features ultra-flat surface and no impact on fine circuit mounting, being the best cost-effective choice for high-precision ordinary lead-free PCBs.

Description

Specifications & Functional Features
– Surface Material: Organic Solderability Preservative Film
– Film Thickness: 0.2–0.5μm (ultra-thin and uniform)
– Surface Flatness: Perfect flatness, zero unevenness
– Environmental Performance: Green, non-toxic, fully RoHS compliant
– Solderability: Excellent, suitable for ultra-fine line and fine-pitch component soldering
– Process Advantage: Lowest cost among all lead-free finishes, super flat, no solder bridging
– Limitations: Short shelf life (3–6 months), only supports limited reflow times, strict vacuum packaging required
– Typical Applications: Computer motherboards, precision consumer electronics, 5G small signal boards, high-density fine-line PCBs

Working Principle & Process Diagram Description
Working Principle: Organic molecular self-assembly protection. After strict cleaning and micro-etching, the bare copper surface reacts with water-based organic preservative solution (Benzotriazole/Imidazole compounds). Organic molecules form stable coordination bonds with copper atoms, attaching a uniform ultra-thin organic film to cover copper traces. The film isolates oxygen and moisture to prevent oxidation, and it decomposes & volatilizes during high-temperature soldering to expose pure copper for perfect welding.
Process Flow: Acid Cleaning → Micro Etching → Surface Activation → OSP Film Coating → Low-temperature Drying