On Sun, 22 Jul 2001 04:49:57 -0400, you wrote:

>At 11:16 PM 7/21/01 -0400, you wrote:
>>
>>I believe the cost to set up a single production line for handling CSP
>>parts - with rework (removal and replacement of CSP parts) is on the =
order
>>of $2.5M.  Double this for an X-Ray laminography tool (Agilant has some=
 nice
>>ones you can buy - but remember to reinforce your floor; they weigh =
about 6
>>tons each)!
>
>That may be true, for new stuff anyway, but I would have no problem =
getting
>a small quantity such as 100 pieces of CSP or BGA board assembled, with
>X-ray inspection, for a reasonable price, and I don't think anyone else =
in
>an industrialized country would. I agree it's (probably) out of the =
hobby
>category, but it *could* be within easy reach of small businesses. 0201 =
parts
>and the small 8 "pin" NS CSP parts like the old 555 and TL431 are also
>things that I will likely never assemble myself with my trusty Weller =
WCTP
>solder station (or the Metcal, for that matter). Some of the COP-8 =
micros
>are available in a 28 pin CSP package, which would be really nice for =
some
>applications (but, IMHO, we need flash/ISP for it to be practical in =
small
>quantities).
Actually, CSPs and BGAs are not as difficult as you might think to
hand- assemble, given practice and a steady hand!. The solder balls
make them self-position by surface tension as long as they are roughly
in the right place to start with. I have a friend who routinely
replaces and reflows BGAs on cellphones with nothing more than a
hot-air tool.=20
As for inspection - if you want X-rays, try your local vet, dentist or
hospital ! May take some trial & error with exposures but I'm sure it
would be viable if you only need the odd one or two every so often.=20

The biggest obstacle to cheap development with the zillion-pin BGA
devices is the need for multilayer PCBs.

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