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CPG196 ball grid array - don't try this at home?
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ebastler:
I am looking to design a small FPGA board which needs to fit into a DIP-40 socket. Initially thought I'd use an iCE40UP FPGA, but that turns out to be under-powered for my needs. So the Spartan-6 in its small CPG196 ball-grid array looks like a good choice. 8*8 mm² footprint -- but it comes with a somewhat intimidating, small-pitch BGA: 14*14 balls in a 0.5 mm pitch.

PCB manufacturing is the first hurdle: Xilinx recommends a 0.15 mm drill for the vias, while the low-cost PCB houses seem to use a minimum drill size of 0.2 mm. I guess that problem can be solved by going to a more expensive place... But how about populating the PCBs?

This is strictly a homebrew project, and I plan to hand-solder just a few of these. Is it a realisitic endeavour to try that, say with hot air from above and a pre-heating plate from below? Or would you say that the tolerances are too ambitious?

Thank you for your feedback or experiences with this type of package!
PA0PBZ:
Probably not helpful at all, but when I read DIP-40 I remembered this: https://www.micro-nova.com/mercury
cgroen:

--- Quote from: ebastler on April 16, 2020, 11:44:55 am ---I am looking to design a small FPGA board which needs to fit into a DIP-40 socket. Initially thought I'd use an iCE40UP FPGA, but that turns out to be under-powered for my needs. So the Spartan-6 in its small CPG196 ball-grid array looks like a good choice. 8*8 mm² footprint -- but it comes with a somewhat intimidating, small-pitch BGA: 14*14 balls in a 0.5 mm pitch.

PCB manufacturing is the first hurdle: Xilinx recommends a 0.15 mm drill for the vias, while the low-cost PCB houses seem to use a minimum drill size of 0.2 mm. I guess that problem can be solved by going to a more expensive place... But how about populating the PCBs?

This is strictly a homebrew project, and I plan to hand-solder just a few of these. Is it a realisitic endeavour to try that, say with hot air from above and a pre-heating plate from below? Or would you say that the tolerances are too ambitious?

Thank you for your feedback or experiences with this type of package!

--- End quote ---
I have soldered countless BGA's with 0.6mm pitch on a hotplate at home (reflowr), not a single hickup! PCB and stencils from JLCPCB (via holes was 0.2 however!)
ebastler:

--- Quote from: PA0PBZ on April 16, 2020, 11:53:00 am ---https://www.micro-nova.com/mercury

--- End quote ---

Neat, but those guys have made it a bit easier for themselves: That's a DIP-64 package (68000 size); it is wide enough to fit the TQG144 package. I don't have that room unfortunately.


--- Quote from: cgroen on April 16, 2020, 12:01:13 pm ---I have soldered countless BGA's with 0.6mm pitch on a hotplate at home (reflowr), not a single hickup! PCB and stencils from JLCPCB (via holes was 0.2 however!)

--- End quote ---

Thank you, that's reassuring! I will start dabbling with the layout, and will check how 0.2 mm holes look in that crammed neighborhood of the 0.5 mm BGA pitch. Prices go up a lot if I really need 0.15 mm drills...
cgroen:

--- Quote from: ebastler on April 16, 2020, 04:00:30 pm ---
--- Quote from: PA0PBZ on April 16, 2020, 11:53:00 am ---https://www.micro-nova.com/mercury

--- End quote ---

Neat, but those guys have made it a bit easier for themselves: That's a DIP-64 package (68000 size); it is wide enough to fit the TQG144 package. I don't have that room unfortunately.


--- Quote from: cgroen on April 16, 2020, 12:01:13 pm ---I have soldered countless BGA's with 0.6mm pitch on a hotplate at home (reflowr), not a single hickup! PCB and stencils from JLCPCB (via holes was 0.2 however!)

--- End quote ---

Thank you, that's reassuring! I will start dabbling with the layout, and will check how 0.2 mm holes look in that crammed neighborhood of the 0.5 mm BGA pitch. Prices go up a lot if I really need 0.15 mm drills...

--- End quote ---

One thing, I constantly violate JLCPCB rules of 0.2/0.45 via, I use 0.2/0.352 instead, they never complain, and the board works :)

EDIT: check here, details about my boards: https://www.eevblog.com/forum/microcontrollers/pcb-for-a-bga-microcontroller/msg3013184/#msg3013184
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