Issue link: https://iconnect007.uberflip.com/i/1243344
16 SMT007 MAGAZINE I MAY 2020 wet as well ends up becoming an advantage. Because the reason being that an electronics designer can space the pads closer in your cellphone and get more components crammed in. However, that was an unexpected benefit that few people recognize, even today. Feinberg: Let me get back to my question about the nickel. The largest cost for the assem- bly industry is recycling the dross, and many assemblers don't realize until someone sits down with a pen and pencil and shows them. Does the nickel do anything to reduce the per- centage of dross that's created? Lasky: Yes, it does. Let me state that I'm not as knowledgeable in this as I am solder paste, but I believe they also put a small amount of some other elements in like germanium. We're talking like something like 0.05%; it's not even close to 1%. If you don't get the amount right and you put too much in, it won't work. It must be very precise. For wave soldering, I believe these alloys with trace metals, such as nickel and germanium, have become regu- larly used. Again, my expertise is more in sol- der paste. Johnson: I'm getting the sense that there is frac- turing in the formulations, a period of devel- oping specialized formulations to fix particu- lar problems. Lasky: It's important to point here that it's not in the metal alloys; it's in the manufac- turing of solder paste to try to solve differ- ent assembly problems. The point I was mak- ing is you would like to have one solder paste that would solve all of the different assembly problems, but that is likely impossible. As an example, a solder paste might be developed that's good in solving the voiding problem on QFNs. It can be developed so that it's quite good in other aspects, but if there's a com- pany that their main issue is a head-in-pillow defect in BGAs, there's probably another sol- der paste that's a little bit better in that regard and maybe not quite as good in voiding. But this company that's having the head-in-pillow problem doesn't have a voiding problem. It's a fact of life that any type of manufacturing process is an optimization process. It's very difficult to make one solder paste that is the best at everything. Johnson: Taking us back to the certification issue you were talking about earlier. If there are a variety of solder paste formulations out there, and selecting the right one for your man- ufacturing challenges is part of the process, how do you do that? Lasky: One of the things that should be a bless- ing to users is solder suppliers who have tech service engineers. If a customer has a prob- lem, the first thing they should do is get on the phone and talk to their solder paste supplier's engineers because they solve these problems every day. If you say, "I'm having a problem with a head-in-pillow defect," the tech ser- vices person will ask you, "Which of our sol- der pastes are using?" If you say, "I'm using formula D," they'll respond, "That's the one that's made more for voiding, while formula B is the one that's best for using on the head-in- pillow defect." Often, you can solve your prob- lem with a phone call instead of a lot of exper- imentation. I always suggest to people that when they have assembly problems, first call your materi- als or equipment supplier's technical experts. If you're having trouble with placement or sten- cil printing, call your placement equipment or stencil printing company because these people do this work every day with customers all over the world, so they have seen about everything. In your company, you only see one thing. Use your suppliers and technical experts for both equipment and materials. Matties: Dr. Ron, thank you for your time today. We greatly appreciate it. Johnson: Ron, thank you. You've given us a lot to follow up on. Lasky: Thanks so much. SMT007