[Olpc-open] Request for information for repairing boards

[Drew Scott Daniels]

Hi,
I tried to add this to the wiki, but it did not work. The following is a
section that might be useful when designing a PCB, or working with
people that might repair the population (of chips...) on the board.

=== Printed Circuit Board (PCB) Design Considerations ===

Some hardware repair facilities could use the following:
- Silk screened outlining of parts
- Silk screen labelling of parts
- Schematics and layout guides
- PCB's designed such that they can be reworked (e.g. don't make the
  power plain keep the board from getting up to temperature)
- Rewaving of boards? This commonly can solve solder problems
- Parts lists
- data sheets and errata for parts (to help look for replacement parts)

It also worries me that I see very little information about the
hardware. I have not seen any schematics, layouts, or even parts lists.
I see some of the big parts are discussed of course, but even knowing
information about the supporting chips is useful.

Also, being ROHS compliant means that the solder used is harder to melt
and work with. Some people say this might lead to lower yields, and it
certainly makes it more difficult to repair (although, perhaps not too
significantly?). The lead free solder melts at a higher temperature.
This means that some wave machines can't safely get up to temperature to
rewave a board.

The COMBO cards used by cesnet give out some of this information.
Ideally there would be OpenSource tools available to make modifications,
but this may not be practical, and for OLPC might be unnecessary unless
they were willing to allow small shops to build boards.

Thanks,


     Drew Daniels
Resume: http://www.boxheap.net/ddaniels/resume.html
P.S.: Please CC me in replies