PCBA Solder Formulations - China PCBA Supplier

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A necessary component for creating mechanical and electrical connections during printed circuit board (PCB) assembly is solder. But how can you choose the "best" solder type for your specific PCB application when there are so many different solder alloys with varying characteristics available?

Weakened mechanical integrity, broken joints under heat stress, higher electrical resistance, overheated damage, solder balls or beading, or cracked joints resulting in intermittent contacts or complete failure are among the potential problems associated with employing inappropriate solders.

Common solder formulations based on tin and lead are listed below. The fraction represent percentage of tin first, then lead, totaling 100%:

63/37: melts at 183 °C (361 °F) (eutectic: the only mixture that melts at a point, instead of over a range)

60/40: melts between 183–190 °C (361–374 °F)

50/50: melts between 183–215 °C (361–419 °F)

For environmental reasons (and the implementation of legislation such as the European RoHS (Restriction of Hazardous Substances Directive)), lead-free solders are becoming more extensively used. Furthermore, as young children frequently put objects in their mouths, it is advised to use them outside where precipitation such as rain may wash lead into groundwater. These recommendations apply to any area that young children may come into contact with. Sadly, most lead-free solders are not eutectic formulations; instead, they melt at a temperature of about 250 °C (482 °F), which makes it more challenging to make sturdy junctions with them.