Solderability measurement of copper with different surface finishes

This article deals with solders wettability measurement of materials with different surface finishes, which are commonly used as solder pads on printed circuit board. The measurement was carried out on two type of solders (Sn63Pb37, Sn95,5Ag3,8Cu0,7), two types of fluxes (94-RXZ-M (IPC-ANCI-J-STD-004 - REL0), 323-ITV (C-ANCI-J-STD-004 - REL1)) and as testing material we used one-side plating PCB (FR4) with four types of surface finishes (pasivated copper, H.A.L, immersion tin, chemical gold plating). For the measurement we have used one of the commonly used wettability evaluation methods - wetting balance (meniscograph) method. Wetting balance method measures the wetting force when the test specimen is immersed into the molten solder bath. Wetting force is measured as a function of time and recorded as wetting curve. We marked the wettability, according to the shape of wetting curve, for each testing combination and sorted them into the table.