These past many years, I've been frustrated by the proliferation of chips I want to use that are only available in BGA (Ball Grid Array) packages with sub-millimeter ball pitch - or that are available in large leads-around-the-edges packages, but not in compact, reduced-lead-count options for those times when you need the internal functionality but not all the I/O.
Quad Flat Pack and Quad Flat No-Lead parts are no problem, but (aside from the soldering and inspection issues) BGA parts require some crazy fine feature sizes and a bunch of copper layers to extricate the signals from under the package. This gets to be an expensive proposition, especially when looking at a prototype board run; the big-name fab houses can do it, of course, but it's always been in full-service territory, with multi-thousand-dollar setup charges.
Well! I just re-evaluated the situation, and it turns out that both Seeed and JLCPCB can now handle design rules that allow orthodox use of 0.8mm pitch BGA parts... and they can do 6-layer boards at a price that, while out of "hobby" territory, won't break the bank for a garage-stage startup. I'm looking at somewhere between $200 and $400 for a small batch of business-card-sized, 6-layer boards with 4 mil trace & space and 8 mil minimum drill, and quite reasonable pricing for a small production run. Which, according to a quick test with DipTrace, should let me use BGA-packaged microcontroller and FPGA parts for the "performance edition" Gadget core (the standard core will continue to use a non-BGA microcontroller and no FPGA).
Also, the current fab capabilities seem to allow use of USB type C connectors, whose nasty footprints were seriously problematic for prototyping when last I looked, a couple of years ago. I need to consider whether to switch to Type C for the production Gadgets, or stick with Mini B (the range of available cables will be a consideration here, as well as connectors for a custom hub).
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