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NOVEMBER 2020 I PCB007 MAGAZINE 33 Most of the shops have that technology in-house nowadays; those machines are on the mar- ket. From a process point of view, using the same technol- ogies we use today, there are some modifications. The pro- cess, in terms of a sequence, is different, but not too different from what it used to be. That's a fairly known approach. No new materials or processes or technologies are involved. Just the sequence is different. Johnson: Does that mean that you can run traditional fabrication processes and VeCS processes on the same line? Do you just run the gates in a different order? Tourné: We rout the slots, drill the BGA pitch- es at the same stage, plate it up, and fill it up. We can do microvias in combination if it's a very dense outer layer pattern. We can keep it clean and use microvias on top of the VeCS slot at very fine BGA pitches we always talk about. Dickson: The manufacturing capability has evolved. We were using 10-year-old routing machines and non-vacuum fill vias for VeCS- 1 slots three years ago and able to do VeCS-1 with back-rout slots pretty easily with conven- tional technology, but the customers kept ask- ing for more. Now, we're able to do advanced blind VeCS controls. We can do multiple depth blinds. We're getting tighter and tighter on the elimination of even the stuff of the VeCS. These are all CCD aligned routers, which were fairly new to the PCB industry. We have high vacuum via fill machines now that can squee- gee the surface and create a flat resin surface, even in very deep blind slots. We now have units that are more advanced than we did when we first started. We were able to build the products with both pieces of equipment, but the reliability and process con- trols are much better on the new equipment than what we had in the past. Some of the structures we're building utilize more than just VeCS. In its simplest form, VeCS is an interconnect technology. It creates two vias in one cut that has extremely dense rout- ing capability. But it also has the capability of matching the impedance of the signal on an X and Y plane in the Z-axis. With thicker boards, when you run your time-domain anal- ysis, you can see that the im- pedance is matched all the way through the interconnect. There's real value in that, and they'd like to see struc- tures where you use VeCS with some type of through-hole somewhere else, like in the BGA or in another area, and pos- sibly in addition to HDI. That's where I see VeCS really parking itself. It's going to be the advanced SI, reliability, and performance in- terconnect, along with HDI through-hole vias. Matties: With this process, where does the de- sign community fit in? Is there a new learning curve that they have to go through, or is this something that is intuitively in place? Dickson: That's probably the biggest learn- ing curve. We can help them as much as we can to move to the next level and design with VeCS; there's a paradigm shift between the limitations of only being able to do stack HDI routing or through-hole. Three years ago, software and tools were not available. Now, most of the major design tools can de- sign in VeCS, but it's a true paradigm shift. The designers who are capable of doing this are showing us stuff that Joan and I probably never thought of even as a conceptual idea. I saw one the other day where they had VeCS from the backside connections as a VeCS-2 blinds through-holes in a section on the top and HDI on top of it. They were looking at doing 0.3-millimeter BGA conversion into the PCB with no substrate interposer. I didn't re- ally think of that when we were starting the applications (laughs). But with the capabili- ty of being able to go so deep into the board Joe Dickson

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