However, making a change to a new solder paste is not a drop-in solution, nor is it always the correct solution. One of the biggest advancements has been in changes to solder paste chemistry. Voiding is attributed to the flux outgassing within the solder joints while the solder is in a molten state. This is why voiding is such an important issue. We deal with the problem of voiding during manufacturing, yet it is the final effect on a product that is key, and sometimes that gets lost. Typically the process window is focused around the solder paste, but often some components cannot accept the temperature tolerances of many lead-free solders. The next challenge is the reflow process window. They range from small PCB assemblies with miniaturization of parts and often a BGA to very large, heavy, double-sided PCBs with ground planes, heat sinks, and densely populated components.Īdded to that is the mixture of circuit board components that cannot be seen with the naked eye, all the way up to tantalum capacitors, BGAs, QFNs, plastic connectors, shields, and much more. Some assemblies seem to ignore any design for manufacturability (DfM) rules. In addition, the variety of PCB assemblies is incredible. With miniaturization and many bottom-terminated components (BTCs) we continue to struggle to find the true causes and the ideal solutions. It continues to be a problem for lead-free assemblies, but the problem has become even more complex. Voiding has been a challenge for quite some time, primarily with BGAs, ever since the shift to lead-free soldering was discussed in the U.S.
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