First, thanks to all for your responses.

   I guess to clarify what I am looking for is, what are the layout=20
design rules/constraints that I need to be aware of when considering an=20
FCB design?  I would anticipate that a PGA package would be a bad thing,=20
but what are the practical limits or guidelines that I should follow? =20
What are the special considerations that are unique to FCB design and=20
layout?  I am sure that this things have been outlined someplace, but I=20
have been unable to locate them.

-Phil-

-------------------------------------------------------
  The day the world runs out of beer,
    is just too terrible to think about.
-------------------------------------------------------

On 10/9/2015 3:30 AM, alan.b.pearce@stfc.ac.uk wrote:
>> The secret is in the circuit design. There are rules such as aligning th=
e
>> components with their longest side parallel to the folding lines.
>> I don't think the camera manufacturers assemble the parts after the boar=
ds
>> are folded. Perhaps a second reflow in the oven after the board is folde=
d
>> may help to release the stress.
>>
>> Some parts like QFPs will not be possible to assemble on a bent board.
> Agreed. I came into the project late, and apparently an early assembly ha=
d components bottoming out because they hadn't been aligned as you say. For=
tunately we didn't have any QFPs, so that wasn't a problem. What was a prob=
lem (and the reason I got involved) was that they had farmed the PCB layout=
 to an outside contractor who used pad sizes that were too small, and when =
hand soldering the ceramic capacitors were getting cracked because they tou=
ched the components with the soldering iron. This board assembly was too la=
rge to reflow solder - it was around 15 inches in diameter. The components =
were placed on the board after it had been formed into the tube - it was th=
e only way to do it, the stress on the components would be too much otherwi=
se.
>
>
>

--=20
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