Reliability Threats Fine Pitch Through Hole Soldering

Miniaturization continues in all kind of electronic assemblies and thus also in the different soldering processes. Not only consumer electronic assemblies become smaller, but also in other areas like automotive, industrial and medical parts reduce in size where functionality increases. No matter if products are assembled in high or small volumes soldering technology has to deal with finer pitch and higher accuracy of the soldering process. Small electronic assemblies contain mainly SMD components that are soldered with solder paste in a reflow oven. Traditional through hole soldering is replaced by surface mount devices nevertheless there are still some reasons to have through hole components instead of SMD’s. The main two reasons are strength (reliability) and heat resistance. Some components like flex cables, LCD displays and other plastic parts just cannot withstand the high reflow temperatures of ~ 250 ºC for a longer time. In order to meet the high temperatures of reflow special high temperature resistant plastics are required; making the parts more expensive.