Issue link: https://iconnect007.uberflip.com/i/1010078
18 SMT007 MAGAZINE I AUGUST 2018 that to the cost of doing it wrong. They may be pennies to do this process or use this analytical test versus this one, it's cheaper and faster, but the cost of failure is always going to be higher. It drives them to prove out to really qualify their wash process while they are doing their first article inspections. Las Marias: Greg, in the PCBA industry, one major cause of defects is the paste printing process, and a part of that process is the stencils. From your perspective, are there critical challenges when it comes to the chemicals used for the stencil cleaning process? Greg Smith: Yes, I see both in small and high- volume manufacturers where stencils are not properly cleaned when they are put back on the rack. Many times, I've seen stencils pulled from the shelves and put into production with inadequately cleaned apertures. Of course, this causes printing challenges. Over the years a lot of people just use IPA for stencil clean up. Today there are many really good cleaners on the market that are much more effective than IPA. As component miniaturization continues, stencil apertures continue to get smaller and smaller. It is extremely important that the correct cleaning chemistry is used in both the printer and the stencil wash equipment. Matties: That is an easy problem to resolve. Is it just a matter of having the discipline to follow the process that causes this? Smith: I believe it is, especially for standard stainless-steel stencils. The more challenging issue now is the proper cleaning of nano-coated stencils. As more and more companies use nano-coated stencils, it is very critical that they change their cleaning processes to maximize the life of the coatings. Many of the current cleaners being used for standard stainless-steel stencils can attack these coatings and cause premature wear. Also, elevated temperatures can damage the coatings as well. Replacing current cleaners with new pH-neutral chemistry that work at ambient temperatures will help customers get maximum life from these coated stencils. Matties: Right. It just seems like an elementary problem, that it is something that any good production manager would insist upon a solid process and verification. Smith: Yes, it is very simple. Good inspection processes after the final cleaning cycle will make sure the stencil performs as it should the next time it is used. Matties: Does your company sell the cleaning process as well or just the stencils? Smith: One of our sister companies recently developed our own cleaning process. But there are several different chemistries out there now made specifically for coated stencils. Camden: On the ceramic stencil side, you have to state the precautions because most people will just take their coated stencils and put it in their standard stencil wash. So, there can be issues. Matties: What's interesting here is that the conversation between you, Greg, Paco and Eric, all are talking about discipline with the process, understanding the process, and utilizing the process correctly. And again, it just seems basic, but what do you think the struggle is for people to follow that process? Why is there a struggle? Camden: I think the challenge becomes almost like a lost art form, for people to own their own process instead of like building Legos. They Greg Smith, BlueRing Stencils