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18 SMT007 MAGAZINE I FEBRUARY 2020 The question fabricators had when we were approached with this was, "Who pays for the board when the component is bad?" The shops, customers, and EMS suppliers aren't going to pay for it, and then it stops. Matties: The decision to go with the active embedded is a design or an OEM decision.But the advantage of active embedded is enormous, according to AT&S, because you get a lot more functionality out of a lot less space. Korf: There's no question. The liability discus- sion is what's holding it all up. Who's going to pay for it? Matties: This has been great. Thank you very much. SMT007 a few devices. Most people put down a cav- ity instead so that they can access it from the outside. It's almost a catch-22. No one wants it, so no one's going to fund some- one to do it. It needs a couple more people. You're correct in that AT&S is a good leader in this. A couple of Japanese companies are also driving this, but it's a relatively low-vol- ume process. However, their applications will typically be in fairly high volumes on a part-number basis. Matties: They talked about supply chain chal- lenges for this technology. Korf: Big issues come up. I did an investiga- tion once where we tried to put 132 devices in a module embedded, and the yield was zero. In the last 20 years, the electronics industry has been making adjustments to accommodate shrinking compo- nent sizes, and the shrinking trend continues to grow. High-precision fiber laser cutting systems allow sten- cil manufacturers to cut an aperture as small as 0.00025", but that doesn't mean that solder paste will get through that opening. Metals with smaller grain structures, nano- coatings, careful solder paste selection, and proper aper- ture design work together to achieve optimal paste release. However, the challenge doesn't stop at simply get- ting the paste to release from the stencil. The appropri- ate solder volume required for each device must also be achieved. This can be difficult with densely populated boards that have a high mix of devices (i.e., connectors on the same board with micro-BGAs), especially utiliz- ing a single stencil thickness. The aperture design can be manipulated to a point, but the area ratios must be met to maintain paste transferability; often, maintaining a 0.006" stencil thickness for those big connectors can- not be done with small chips and other micro-devices on the board. While there have been significant advancements in paste deposition machines, or jet printing, stencils are still the most effective tool for high throughput. Multi- level stencils (step stencils) have answered the call for these high mix boards, allowing for optimal paste volume for multiple device types with a single stencil. The con- nector now gets the 0.006" deposition it needs, and the micro-BGA has a nested pocket, allowing for 0.004" paste deposition. (Source: Stephanie Hardin, Integrated Ideas and Tech- nologies Inc.) Changing Dynamic in Stencils

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