Mixing Leaded and Lead-free BGAs onto One PWB (PCB) Assembly (June 4, 2013)

RoHS (lead-free) solder processing is by far the industry standard in assembling electronic circuit cards today.  As a result, RoHS packaging dominates the component industry.  If SnPb (tin-lead) solder processing is customer requested (typical in MilAero applications), RoHS components such as TSOP, QFN, QFP, SSOP, passives, etc., do not pose a problem as the amount of solder contained on the part is very small.  BGA packages however, can become an issue.

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Leaded and lead-free in one assembly

In regards to BGAs, SnPb (tin-lead) balled packages are still available today but usually at the expense of extremely long lead-times, typically 20+ weeks.  The standard approach is to reball RoHS BGA packages with SnPb balls and process the entire assembly with SnPb solder.  On occasion, though, there comes the unusual customer request of mixing component solder chemistries, placing and reflowing both RoHS and SnPb balled BGA’s on the same circuit card assembly.  What do you do then?….call NPI Services!

Although combining leaded and lead-free BGAs on a single SMT assembly is unusual, NPI’s assembly operations expertise makes quick work of such requirements.  Employing specific solder assembly techniques and by maintaining a single reflow profile above min RoHS and below max SnPb’s reflow temperature points, NPI’s assembly operation can successfully combine these two solder chemistries onto one PWB (PCB) assembly.  Whether it’s for production or a quick-turn prototype run, let NPI provide solutions to your challenges.