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I'm (still) looking to move from QFN to BGA to be able to fit more stuff in to the same size board. My sticking point at the moment is the price to get the PCBs fabricated. I asked a PCB manufacturer, and the cost to go to 4mil space/trace for a 4 layer design (from their normal 6mil limit) was $140 
If I was making stuff professionally, of course that wouldn't be any issue... but I'm just learning as a hobby/spare time filler so any cost saving measure when I expect to make mistakes is a good thing.
Please could someone more experienced than I am let me know what I should be aiming for to reduce PCB costs for specs to handle a few 0.8mm pitch BGA parts?
For example, what would the expected order of these from lowest to highest cost be?
- 0.3mm vias -> 0.2mm vias
- 6/6 down to 4/4
- filled vias in pads
Or there's the "cheating" options:
- DIY filled vias in pads
- aim for 5/5 and hope it's fabricated OK
- Reduce pad size and make via rings slightly smaller than allowed, so that 6/6 fits
Any 1 of those would be enough (I think), I'd just like a little advice on what to get a quote for and then I'll start on the layout to fit that spec!
- Comments(1)
A****min
Dec 03.2019, 18:27:57
If your problem is cost, stack a pair of two layer boards. 
A four layer board costs, well, basically, twice what a two layer board does, give or take additional labor.
If you need circuitry per dollar, in a limited volume, you'll probably get there better with cheaper stock. If you must have four (or more) layers for absolute maximum density, well, put your money where your space is(n't).
