- posted
16 years ago
[ shudder ]
Buried Vias
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- Vote on answer
- posted
16 years ago
Do everything else first. This includes not using a FBGA part.
- Vote on answer
- posted
16 years ago
Why? They're just normal through-hole vias that have been plated over with pre-preg...
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- posted
16 years ago
Each layer has to be (before lamination) drilled and through-hole plated in several stages. Many more process steps, meaning lots more $$$ and less yield/reliability for a given level of technology.
Best regards, Spehro Pefhany
-- "it\'s the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
- Vote on answer
- posted
16 years ago
A bit off topic but I was wondering about vias and component plated throughholes, if a PCB is 1oz or 5oz copper plated will this significantly decrease the hole diameter for components for the 5oz board? If the throughholes plate at the same thickness as the traces, I think the 5oz boards will have 0.35mm taken off the diameter of the throughholes. (0.0014" per oz plated) Is this correct?
cheers, Jamie
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- posted
16 years ago
Sounds correct, call the PCB shop and be sure. Some vias might end up plated shut.
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- posted
16 years ago
We specify finished hole sizes.
John
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- posted
16 years ago
If you're doing fast stuff on many-layer boards, you have _got_ to get rid of the via stubs...so it's either buried vias or back-drilling, which causes its own set of cost and reliability headaches, as well as taking up a lot of valuable real estate.
Cheers,
Phil Hobbs
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- posted
16 years ago
No because you don't know how much copper was on the board and how much was plated and the shop will drill holes bigger to achieve the specified finished size with the plating.