EFFECT OF SURFACE COATING AND FLUX TYPE ON THE SOLDERABILITY OF PCB BY LEAD-FREE SAC305 ALLOY

This paper presents the results of tests on the effect of the surface coating and flux type on the solderability of PCB by lead-free tin-based SAC305 (SnAg3.0Cu0.5) alloy determining the size of the contact angle by a wetting balance method. The study was performed at a temperature of 260°C on PCB with three types of coatings (HASL LF - lead-free, ENIG - gold, OSP - organic coating), using two types of flux (EF2202 and RF800). The shortest wetting time t₀ = 0.6 s for the EF2202 flux and t₀ = 0.98 s for the RF800 flux was obtained for plates with the OSP coating. For ENIG-coated PCB, the wetting time t₀ = 1.36 s (EF2202 flux) and t₀ = 1.55 s (RF800 flux) was the longest. The calculated angle θ was as follows: for PCB with HASL LF - θ = 45°, with ENIG - θ = 58°, and for the OSP coating - θ = 63°.

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