Issue link: https://iconnect007.uberflip.com/i/1526114
10 SMT007 MAGAZINE I SEPTEMBER 2024 Feature Interview by Nolan Johnson I-CONNECT007 As members of the technical staff at Indium, Adam Murling, technical manager, and Dr. Ron Lasky, senior technologist and professor at Dartmouth University, know their way around metallurgy and solder formulation. I corralled them for a conversation on solder application techniques from the solderer's perspective and their insights did not disappoint. Nolan Johnson: Adam, what are some threshold moments when you would use solder jetting over solder printing? Adam Murling: It can be a tandem approach; it doesn't have to be all-or-nothing. Let's say you have a four- or five-mils-thick (100 to 123 micron) stencil, but you also have really fine- pitch BGAs on the same device. ere's an argument to be made for not cutting those stencil apertures out because the area ratio will be too challenging. Essentially, you are print- ing everything except the fine features, which you jet or dispense. Aer printing and inspection, you could have a jet printer or dispenser downstream to take care of those finer deposits. It is important to make sure the solder paste chemistry in your dispensing or jetting equipment is compatible with the paste you're using in a screen printer; compatibility is key. But what happens when some component leads are too large? You have mostly smaller devices—the 008004, 01005, and even the 0201 passive components and 0.3-mil (75 micron) pitch BGAs, etc.—but you also have connec- tors that require more solder volume than a three-mil stencil can provide. In these situa- Scrutinizing Solder Printing