Solderability of Coloured Lead Free Solder Composite

Coloured solders offer wide range of possible application on top of conventional usage related to solder and soldering. Coloured solder can be produced by adding colour pigment into solder formulation to form coloured solder composite. The performance of coloured solder joint typically determined by good solderability, which influenced by wetting properties. The objectives of this paper is to investigate the solderability of coloured lead free solder composite with different formulation type of colour pigment and variation of colour pigment composition. Green and “glow in the dark pigment” with composition of 5% and 10% respectively were added into the lead free solder paste. Each coloured solder paste was stencil printed on the PCB and then reflowed using reflow soldering process. The wettability of the solder composite was measured and observed using Infinite Focus Measurements (IFM). The results demonstrated that coloured lead free solder composite have a good wettability. This finding also indicates that use of green pigment into the solder composite has shown greater wettability as compared to glow in the dark pigment. Higher percentage of added colour pigment of 10% has significantly reduced the wettability of solder composite. Wettability of coloured solder composite with small amount of added pigment is in the acceptable range of contact angle, showing good solderability of joining.