Applying solder to high density substrates

摘要

Process is described for applying large quantities of solder to small areas, such as the lands in a high density card, to which it is intended to surface mount electronic devices or directly attach circuitized chips. The land area is temporarily extended by depositing a relatively thin layer of metal beyond the perimeter of the land, wave soldering to deposit excess solder on the extended land region, and reflow, whereby the thin layer of metal dissolves into the solder, causing the solder to retract to the dimensions of the original land. Because the volume of solder is increased, the strength and reliability of the solder joint is greatly improved.