Here's what we do... we use 3 mil (.003") diameter thermocouple wire, and we route the wire to the ball that we select, with the wire exiting the BGA between balls - using solder mask touch-up to tack the wires in place. Then we solder paste, place, and reflow the BGA device with our rework system... once cooled, we tack the 4 corners of the BGA in place using an adhesive (so that the BGA isn't accidently dislodged from its' pads during reflow cycles). After this operation, we have a fixture we can use over and over again. At 11:25 AM 11/07/2002 -0500, you wrote: >A couple quick questions regarding temperature profiling of BGA's at a >re-work station. > >I posted maybe a month back and from the (2) responses I gather that >drilling holes to feed the thermocouples from under the board is the >standard practice. > >I tried this, however the best I could do was *attempt* to ensure that there >was contact between the tip of the thermocouple and a BGA solder ball. (the >thermocouples came up from under the board, and I tried to place the BGA >such the tips of the thermocouples would be in contact with the side of a >BGA ball. I have 3 thermocouples (middle, side, corner) under the BGA, and >the BGA is held down by chip bonder at 2 opposite corners) When I tried >getting temperature values at the re-work station, I was getting >inconsistent numbers. > >The other method I've tried was to use thermally conductive adhesive to hold >a thermocouple between the chip and the board (with no drilling -> ie. the >thermocouple wire lies flat against the board and held down by the adhesive >and the chip). This method seems to result in more consistent temperature >readings. > >Can anyone comment on whether the adhesive method is used and reliable, or >if theres something I'm doing wrong with the drilled board method? > >Thanks, > >Toby Chang >Process Engineerin Co-op >Leitch Technology International Inc. > ---------------------------------------------------------------- Bill Raymond, VP of Technology Development Trenton Technology Inc. 1001 Broad Street Utica New York 13501 Phone (315) 797-7534 Fax (315) 797-7159 ---------------------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------