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16 The PCB Design Magazine • November 2017 THE HDI ROUNDTABLE EXPERTS DISCUSSION If a customer has the design already in hand and wants us to use a certain type of material, if we think that the design will be better and go through easier with a different type of mate- rial, we'll certainly suggest that. We have part- nered with different material suppliers and we often go out with our sales force, with our sup- ply partner at our shoulder, and start the design discussion of HDI work with material. It's very important that the materials work for both the OEM and the printed circuit board manufactur- er. That's critical. Secondly, we want to try to help them and guide them in design, so getting us involved early is just a tremendous help. Then we can confirm the design, confirm the manufactur- ability, and we're off and running. But every- thing is becoming thinner, smaller and tighter. Back in the day, the question was, "Can you get the hole smaller and smaller and through this board?" Now with laser drills, the issue is not about drilling the hole and getting perfect reg- istration. Now the issue is how to get solution through the darn thing. I think more impor- tantly, from a printed circuit board standpoint, the large departments are now in upfront engineering, being a teammate to all the customers who call in. I think the niche in the marketplace is not to simply take the Gerber files and build it, but to really be a partner to the end-customer. Be a help to them and talk out the design and get something that is not only reliable, but manufacturable. Matties: Tony, what percentage of your customers are doing true HDI? Torres: It's unbelievable. Just two short years ago, in 2015, we were do- ing 20% HDI work. Our facility in Santa Clara now does 85−90% HDI work. We're a company whose mantra is to say yes to the customer's needs, in technology and in delivery. We were forced to really learn how to build HDI work be- cause that was their very first question: Can you build this product? Then they want to know how fast we can get it to them. Matties: Was that market demand or was that a capability that you carried out to your custom- ers and swayed them to go in that direction? Torres: It was market demand. The demand came from, as Happy knows, all those IPC meet- ings that we would attend monthly. Now the numbers in North America said that single-sid- ed, double-sided and multilayer boards were all flat at best; HDI technology was the only growth model. Over the last three-year period, flex cir- cuits and rigid-flex had a little bit of growth, but as far as percentage of the business, it was very, very low. The bulk of the business was HDI and so the writing on the wall was clear. That's why we made the shift in equipment and in upfront engineering, and it's paid off. Matties: One of the advantages for HDI is that ultimately your customers wind up with a lower cost for their boards. Is that the result that your customers are reporting? Torres: It is a mixed bag. Moving to HDI tech- nology and keeping layer count down will ul- timately wind up with a lower cost for our customer. However, there are times that, with standard through-hole technol- ogy and lower layer counts, simply adding two more layers may be more cost-effective than moving to an HDI design. Las Marias: Thank you, Tony. Let's go to the assembly side. Vince, from your perspective at MC Assembly, what are the chal- lenges when dealing with HDI boards? Vince Burns: We're listening to the designer and the fabricator talk about getting layers thinner and smaller. But one of the things that we're all discussing here is the temperature cycles. Just starting out, ev- erything that we build here must go through a reflow oven. It has to go through a reflow pro- file. We have to melt the solder so that we can get the parts to stick to the board, so the thin- ner the layers and material get, the more we're Vince Burns