Hi All The key to good, accurate thermal profiling is the thermal connection between the thermocouple and what you are trying to measure. The t/c junction must be at the same temperature as the solder joint you are measuring and there can be wide variation in the temperature of a specific joint depending on PEC design, e.g. a small chip cap joint to a large earth plane joint. After trying many techniques over the years, the one which most truly reflects the actual joint temperature is to use a high melting point solder and "envelop" the end of the 0.005" thermocouple. Try not to use too much solder otherwise you will add to the thermal demand of the solder joint. We often do not have scrap boards to play with either and find that we can, in these cases, use a bare board and fit a dummy component or components using HMP. You can then desolder and clean up afterwards. This means putting a board through reflow several times however they should withstand this OK. Best plan is to plan to measure components with both the highest and the lowest thermal demand to get a good picture of the delta T across the assembly. I would avoid the use of any tapes since this method of fixing is only good for measuring flat surfaces and not complex solder geometries. Bozo is a bit strong though ! Cheers Bryan Kerr Principal Quality Engineer Process and Materials Laboratory AMS Hillend Scotland -----Original Message----- From: Dehoyos, Ramon [mailto:[log in to unmask]] Sent: 25 October 2004 15:00 To: [log in to unmask] Subject: Re: [TN] A poll of sorts...concerning thermocouple attachment *** WARNING *** This mail has originated outside your organization, either from an external partner or the Global Internet. Keep this in mind if you answer this message. The trick is to make sure that the TC wires are molded by hand to lay by themselves on the board and secured with the Kapton or any hitemp tape. They should not by force down with the tape. When the TC stay put time after time through the oven the results will be about 2 degrees lower than if they are soldered with high temp solder. If they are forced down with the tape, the wires will spring up when the glue becomes weak by the heat. So Dr. ZapFart does not know what he is talking about. It is just my opinion, Ramon -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Steve Gregory Sent: Saturday, October 23, 2004 12:10 AM To: [log in to unmask] Subject: Re: [TN] A poll of sorts...concerning thermocouple attachment Hi Phil, I guess I'm what you call a "Bozo". I use Kapton tape quite often when I do my profiling. I however, don't cover the thermocouple tip with it, but just use it to secure the wires. My thermocouple tip is shaped and placed with tweezers to be at the solder joint I want to monitor,and then the wire is secured along the assembly at places so as not to disturb the rest of the components. The thermocouple tip isn't covered by anything...high temp solder, epoxy, aluminum tape, or anything. Just because I use Kapton tape, doesn't mean that I'm a "Bozo"... -Steve Gregory- According to Dr. Zapfardt in the October issue of Circuits Assembly ("On The Forefront")attaching the TC with Kapton tape is for bozos who really are not interested in actually getting accurate profiles, but are just killing time. I couldn't have said it better myself. Phil Zarrow ITM Consulting Durham, NH USA www.ITMconsulting.org --------------------------------------------------- Technet Mail List provided as a 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/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a 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/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- ******************************************************************** This email and any attachments are confidential to the intended recipient and may also be privileged. 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