Summary for tin plating on heat sink Discussion
Tin plating on heat sink is the issue under discussion: Guillermo Espinoza says a CDA110 hard-copper heat sink with matte tin over nickel (ASTM B545, nickel barrier 1.9 to 3.8 µm) meets thickness specs, yet during wave soldering the plated surface appears to melt, creating a splash effect and contaminating nearby PCBA components. The excerpt provided does not include any replies or named expert answers, so no definitive cause is stated in the source. Based on the question alone, the concern is whether the plating system can withstand the solder-wave exposure despite meeting the written specification. The thread title suggests the failure is happening during wave soldering, but the excerpt does not show whether the root cause is temperature, process conditions, or an interaction between the tin finish and solder wave.
May 30, 2013
Q. Dear colleagues
I have an issue with a part, a heat sink (material: CDA110, hard copper) matte tin plated per ASTM B545, with nickel under plating barrier of 1.9 to 3.8 µm). My concern is this part meets the specification of plating thickness, but when the part passes through the soldering wave, the surface of the part (the plating) seems to be”melting”, and causes a “splash” effect and contamination into some components of the PCBA. According to the plating standard, the parts meet with that; also, the temperature of the soldering wave is between 105 to 239 °C. Why are parts failing? I cannot find another reason for this. If have some recommendation, it will be great; thanks in advance!
Guillermo
Guillermo Espinoza
– Guadalajara, Jalisco, Mexico