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78 SMT007 MAGAZINE I FEBRUARY 2020 Feature Interview by the I-Connect007 Editorial Team The I-Connect007 editorial team speaks with Indium Corporation's Chris Nash, prod- uct manager of PCB assembly materials, about how solder and solder paste application tech- nologies seem to be the center of the challenge for moving to smaller components. Chris also addresses the challenges surrounding, solders, fluxes, and materials due to increased miniaturization. Nolan Johnson: With the dynamic of shrinking feature sizes, packaging, features, and landing pads, and all of the smaller sizes going on in the industry, it seems like solder, solder paste, and solder joints are at the center of it all. You must see some challenges deliv- ering good performance in those products. Chris Nash: It has been a chal- lenge since the introduction of SMT. Everything has been shrinking for the last 20+ years. The mobile market is driv- ing miniaturization, and they're venturing into the 0201 metric or 008004 component sizes for capacitors or passives. Passives usually get miniaturized first because there are so many on boards, so they need to try to save as much real estate as possible. After that, then you start talking about some of the components with different pitches, whether it's QFNs with smaller pitches or dual- row QFNs or BGA-type packages with finer pitches down to the 0.25 or 0.3 millimeters. Barry Matties: What we see is that the focus is on finer pitch, and we have heard that the greatest challenge is getting the solder paste in the right quantity through the stencil onto the board to get high yields. Nash: You can look at finer pitch, but you could also say that the compo- nents are being placed in tighter spacings. If you look at a cell- phone board, for instance, you're n o t g o i n g t o see much space b e t w e e n e a c h of the compo- nents. They're trying to use every square millimeter of space on those boards. That can cause challenges with signal integrity and den- dritic growth if you don't have solder paste that is developed specifically for tight spacing or clearance. It can also become difficult for the printing process, as well. When you get into those small apertures for smaller deposits, you have to talk about thinner stencils and smaller area ratios, and it's going to make it extremely challenging Increased Miniaturization Poses Soldering Challenges AVOID: DENDRITIC GROWTH AVOID: SOLDER BEADING AVOID: VOIDING AVOID: CRACKING AVOID: HEAD-IN-PILLOW AVOID: NON-WET OPENS AVOID: INSUFFICIENT SOLDER DEPOSITS DEFECTS ELIMINATED RELIABILITY DELIVERED

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