Peter It only seems like a "circus".... > ---------- > From: [log in to unmask][SMTP:[log in to unmask]] > Reply To: TechNet E-Mail Forum.;[log in to unmask] > Sent: Wednesday, March 13, 2002 7:42 PM > To: [log in to unmask] > Subject: Re: [TN] Solder Joint Mechanical Stress > > Was this strength test written into the requirements when the job was > taken > on? 20 in pounds is quite a torque to apply to an electronic component. > Does your customer have any first-hand experience of circus board > manufacture? - it's sounds like "no", or he'ld understand for himself why > it's a bad idea to perform a test like this. Is it intended to be 100% > inspection? > > The process to stick the heatsinks to the BGA's should have been confirmed > as part of a product qualification test, as should the means and method of > testing the adhesion. Properly specified, this process can then be passed > onto CM's or whoever assembles the boards to repeat. > > For process monitoring purposes, to ensure adequate adhesion is being > maintained, batch sampling can be done, but I wouldn't do it on expensive > "live" product - I would load the occasional board with appropriate dummy > components, mount the heatsink and test those. If there's a problem, stop > and review the processes. > > Otherwise, what is the test going to prove? Either the heatsink comes off, > or the BGA does (especially if it's one of Earl's illigitimate TI things), > or they both stay on the board but the solder joints (ball to board or > balls to device or both) have been unnecessarily stressed, which is bound > to reduce working life by anyone's reasoning - by how much, should have > been one of the HALT test results, using a non-torqued set of pieces for > comparison. > > How to change the customer's mind? Ask what qual tests were done and what > results were obtained along the lines I suggested above, and judge for > yourself if they were adequate. If not explain why you think so, and if > he's still adamant about carrying out the test on live product, get him to > sign a disclaimer removing your liability for failures now or later for > any > boards on which this test has been carried out. > > Can't suggest anything else, but good luck. > > Peter > > > > > Carl Ray > <carlr.ray@SANMIN To: [log in to unmask] > A-SCI.COM> cc: (bcc: DUNCAN > Peter/Asst Prin Engr/ST > Sent by: TechNet Aero/ST Group) > <[log in to unmask]> Subject: [TN] Solder > Joint Mechanical Stress > > > 03/14/02 12:17 AM > Please respond to > "TechNet E-Mail > Forum."; Please > respond to Carl > Ray > > > > > > > I have a customer who is requiring that I verify the bond strength of a > heat sink that is glued to the top of PBGA. The customer has supplied me > with a torque tool to verify the strength of the bond between the heat > sink and the BGA. I have concerns that testing the strength of the glue > bond may affect the solder joint reliability of the BGA. The tool > supplied by the customer is set at 20 in pound torque. Any ideas how I > can "change" my customer mind? > > -------------------------------------------------------------------------- > ------- > > Technet Mail List provided as a free service by IPC using LISTSERV 1.8d > 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 delivery of Technet send e-mail to [log in to unmask]: > SET Technet NOMAIL > To receive ONE mailing per day of all the posts: send e-mail to > [log in to unmask]: SET Technet Digest > Search previous postings at: www.ipc.org > On-Line Resources & Databases > > E-mail 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 > -------------------------------------------------------------------------- > ------- > > > > > > [This e-mail is confidential and may also be privileged. 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Thank you.] > > -------------------------------------------------------------------------- > ------- > Technet Mail List provided as a free service by IPC using LISTSERV 1.8d > 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 delivery of Technet send e-mail to [log in to unmask]: > SET Technet NOMAIL > To receive ONE mailing per day of all the posts: send e-mail to > [log in to unmask]: SET Technet Digest > Search previous postings at: www.ipc.org > On-Line Resources & Databases > > E-mail 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 > -------------------------------------------------------------------------- > ------- > --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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 ---------------------------------------------------------------------------------