| ??? 10/21/09 06:30 Read: times |
#169926 - It's all in what you prefer, I guess Responding to: ???'s previous message |
Andy Peters said:
Richard Erlacher said:
The last five or six colleagues who've attempted to use BGA packaging for short-run (where they couldn't absorb several respins of the boards) products, have found that it requires, typically six reworks of the artwork PLUS x-ray inspection of each assembled board with the costly BGA's, and, at least with prototype houses here in the U.S, they get about a 1% yield, i.e. 10% of the finished PCB's will pass electrical test, and 10% of the assembled boards have successful attachment of the BGA's. Sounds like your colleagues really don't know what they are doing. No, Andy ... You're the only one on the planet who "knows what he's doing." The fact that their PCB houses couldn't hold tolerances in mask placement and layer registration had nothing to do with it. Those guys changed PCB houses, then tolerated the extra setup charges and delay just for their own amusement. SIX revisions of the PCB artwork? Don't they follow the design rules? What are they doing wrong, that requires so many spins of the board? Seriously -- I think every board I've done in the last ten years has had a BGA on it, and I've NEVER had to respin a board because of a BGA fsck-up.
As for the proto houses, maybe they shouldn't use the cheapest possible. The assembly company we use has nowhere near a 1% yield! They wouldn't be in business if that was the case. The fact that U.S. proto houses only manage to get one in 100 PCB's assembled properly has nothing to do with their problems. The fact that the PRC houses get it right every time, or nearly so, has nothing to do with cost either, nor does the fact that the U.S. houses charge 20x as much, take three weeks for what the PRC does in three days with 100% yield ... that has nothing to do with it either, does it? I can assure you that, having once dealt with those U.S. houses, none of my colleagues use them any longer. The only reason those drunks and potheads that screw up 9 out of 10 things they do are still alive is because it's illegal to kill them. In the PRC, they can recycle their reusable parts, anyway. It's a shame they can't do that here. At least some of those guys would prove useful for something. -a I'm pretty comfortable with the fellows I've worked with over the past 30 years. OTOH, I'd be scared to death to work with a guy who does some of the stuff that you say you do, particularly on an APPLE product. The last time I had a decent job done by a U.S. pcb house was over 25 years ago. They've given up due to ever stricter EPA rules, and simply gave up the PCB business. Too bad, because they could hold that half-mil on nearly anything, and had no problem producing tracks that were thicker than they were wide, with really tight spacing. They're the ones who showed me the benefits of the dry-film solder mask. I miss 'em. Too many Americans tip when the service is bad and buy those junk American cars from Detroit, buy newly constructed houses, tolerate lousy cellphone service and watch the rubbish that's on TV. That's why the American standard of living is circling the bowl. They seem to believe that a lot of rubbish is better than a little bit of quality... <sigh> RE |
