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14 SMT Magazine • April 2017 vices, QFNs and things like that that are coming on the market. It's a process that's running ex- tremely smooth. Las Marias: Do you think lead-free soldering continues to be an issue when it comes to reliability? Holden: The industry has al- ready moved to lead-free solder- ing. That was done a long time ago. It's only the military and avionics and a few hold outs that haven't moved to lead-free. I talked to people at the APEX show that were in the military, and they realize that their time is running short because they have fewer and fewer people who support them. If you're going to lead-free then, unlike tin lead where there wasn't much variety, now you've got a whole proliferation of solders and different compati- bility with final finishes, and different suitabil- ity for reliability life. That's one reason why it's so difficult because depending on what you're assembling for, the answers maybe different. Cox: I totally agree with Happy. At Saline Lec- tronics, the majority of our customers are doing lead-free. Lead-free is definitely more of a chal- lenge with flex boards just due to the tempera- ture. Getting good solder joints is definitely a challenge, but it's a challenge that most compa- nies are up for, so it's good. We need new things in our industry. Las Marias: Do miniaturization, increased board densities, and shrinking component sizes impact the soldering process from your perspective? Cox: I don't know if they necessarily affect it from what I can see. We deal with a lot of the 0201s. We're pretty excited to get our hands on 01005s and start playing with them and see if our pick-and-place machines can handle them. We'll need more precise placements to be able to make sure you get a good solder joint. It will be a little bit more challenging for an operator to manually inspect a board with solder joints being so small. But we have our high-tech AOI equipment, so that should not be a problem for us. Patty Goldman: So, you don't see very many of those types of com- ponents? Cox: We see very small compo- nents all the time, but the small- er they get will be a challenge. I don't think it's a challenge that's going to stop us from do- ing anything. It's just a differ- ent way of looking at it; it's a different way of manufacturing it. You have to have more precise placement, make sure the thickness on your solder paste machines are proper, and I think it's going to be awesome. Goldman: What's your biggest bugaboo then? Cox: Our biggest with flex boards would actual- ly be our pallets that we use in surface mount to keep our boards flat during the reflow. We can set pallets up for all different types of boards, but getting one to fit completely flat in there ev- ery time, and make sure the components are go- ing to sit flat when they go through reflow, is a challenge. Most of the time, it's the bigger com- ponents that we see issues with because there's a bigger area to have a bubble in the flex board. Las Marias: Is solder jetting catching up with the paste printing process? Holden: My last six years have been in high- volume production, and solder paste printing and the integral AOI machines are going to be tough to match in terms of jetting. Jetting may be much more applicable to high-mix, low-vol- ume, but for the high-volume automobile mar- ket, mobile phones, consumer products, paste printing is pretty well defined and highly ro- bust. Jetting maybe coming along, but it will have a hard time matching the fancy step sten- cils and some of the other techniques devel- oped in stencil printing. But it may be totally adequate for high mix. I've never seen or we've never used any jetting equipment except for THE COMPLEX WORLD OF SOLDERING Happy Holden

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