What is the one outstanding factor that you have experienced with lead-free SMT printing as it relates to squeegee technology?

The most common concern we have responded to with many end users is that lead-free solder paste sticks to the squeegees more than tin-lead solder paste does. The sticking has negative consequences for the productivity and quality results of any SMT printer.

Transition Automation Inc. has adapted metal squeegee technology to a very fine precision — with polished self-lubricating metal edges and strict minimal surface area squeegee holder designs. We believe that the extra precision and wide proven experience of our technology offers extra assurance for users who are trying to eliminate problems with lead-free printing. Starting with a known good squeegee and knowing it will endure many hundreds of thousands of cycles is certainly a big advantage for users who are increasing their risks with the adoption of these newer and less proven lead-free materials. At this early stage of use, lead-free alloys are presenting many challenges to SMT professionals, from less wetting and less re-alignment (during reflow) to higher temperatures and consequent planarity and thermal expansion defects. The squeegee technology we offer has always been aligned with advanced applications: high-volume and high-value SMT production with difficult fine pitch. Now with lead-free and its challenges, we believe that our Permalex squeegee technology will be adopted more widely.

Do you see any other issues related to squeegee technology and lead-free SMT printing?

Yes. There is a significant logistics problem: It is very important to segregate the tin-lead material from the lead-free material. Because most end users will be supporting both tin-lead and lead-free production, it is important to keep the materials separated to avoid contamination with each other. A small contamination of the lead-free alloy with tin-lead creates yet another alloy that is not suitable for electronics assembly. Our response to this need is to offer “green” colored holders that are easily identifiable, and we also provide sealed tube packaging, which allows users to close the squeegees into containers to prevent cross contamination.