We had a meeting today 9/30/04 to discuss the MCM leakage current problem.

Present:  Jim Lohr, Tracy Sheppard, Tavi Alvarez, Jerry Clinton, Dave Rich, Tom Himel and near the end Diane Kolos came in.



Action items:


Clinton:  Check whether the pitch adapter and the adhesive used to attach it can take 125 degrees C.  [done: The pitch adapter is polyimide and can take 125 degrees C no problem.  The glue can also take the temperature.  It has a CTE of 79 ppm which is a bit of a worry.]


Rich:     Bring the 3 boards which failed the leakage current test at Teledyne back to SLAC from Teledyne (they are SN610, 11275, 11505)


Rich:  Send SN 11505 to Diane Kolos at Goddard to use thermal imaging to locate the problem and then section or plane the board to find the root cause.


Himel:  Send Kolos information about what to power.  Also, discuss with her and other Goddard personnel of her choosing exactly how to examine the board.


Himel:  Double check with Don Knaepple about other boards that were flakey (had behaviour change when pressing on part of the board.)  [done: I had miss understood Don. There is only one such board (SN 11508) and it presently resides in Himel's office.]


Kolos:  Will email Himel (tmh@slac.stanford.edu) an example coupon analysis and a picture or two. This is just so he can see exactly what is checked.


Himel:  This wasn't decided at the meeting, but he will get a bad bare board, and have the weight loss checked as a function of bake time at 125 degrees C.  This will help us determine how long to have Teledyne bake the boards.





Tom Himel was asked to spend 15 minutes summarizing the problem.  He did an excellent job ;) taking only 75 minutes. This dominated the time of the meeting.  All the information discussed was in the document that was previously distributed so is not repeated here.


 We will plan to start having Teledyne bake the boards before reflow.  Parameters will be determined by some of the actions items above.  We will use 120-125 degrees C if the boards can take it as that is what Arlon (the prepreg manufacturer) recommends.  Otherwise we may fall back to 93 degrees C, the normal NASA spec.  We plan to do this not because we are sure it will help, but because it may help (multiple people recommend it) and we don't think it will do any harm and it shouldn't be too expensive.


We will get bad boards from Teledyne and have Goddard study one.  Note that these may not have the same failure mechanism as the ones that fail in burn-in, but maybe we will learn something interesting.