The solder paste deposition process continues to be the leading source of end of line defects in SMT assembly process. Solder paste printing (even though the printing equipment and process has become much more reliable over the past 10 years) is still a complex process where many process variables, materials, environmental influences (temperature and humidity), and human factors, meet.
It is consistently reported that this process step continues to be responsible for the greatest number of end of line defects. Changing the process to accommodate smaller packages, new stencil designs and paste formulations will make it more difficult to maintain high yields.
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