This were discussed before, below follow a copy/paste from that time :

Happy Thursday to you, Mike!

We presented a paper on this topic, "A Comparison of Methods for Attaching
Thermocouples to Printed Circuit Boards for Thermal Profiling," at Nepcon
West this year.  The paper compares the simple and nondestructive methods of
Kapton, AL tape, and thermally conductive epoxy to the traditional method of
high temperature solder.  High temperature solder is still the most reliable
and repeatable method, but we found that AL tape is a reasonable
alternative.  The paper is posted at:
http://www.kicthermal.com/library/nw99-ts19.html

Good Luck with your research,

Greg Jones
Special Projects Manager
KIC Thermal Profiling
775.322.0158
-----Original Message-----
From: McMonagle, Michael R. <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: Friday, April 16, 1999 9:02 AM
Subject: [TN] Thermocouple Attachment Methods


>Happy Friday To One and All!
>
>Now that formalities are out of the way, let's cut to the chase. I'm
>looking for some feedback on how everyone out there is attaching
>thermocouples to PCBAs for profiling purposes. I will be using this as a
>survey for a potential paper abstract on diffferent methods, pros/cons,
>temperature comparisions, etcetera, etcetera. Survey results will be
>posted for all to see, so we may share in others successes and pains.
>Please take a moment to complete and return to my address only (not
>TechNet) to prevent clogging up TechNet and ticking off Hugo. You may
>post to the forum if there are issues you are facing that you want to
>share with all. Thanks for your help, I greatly appreciate your
>inputs....
>
>1) What types of thermocouples are you currently using?
>
>2) If standard wire (Type K), what gage wire?
>
>3) If standard wire, do you buy preassembled or 'roll your own'?
>
>4) What is your method of attachment for profiling?
>        (solder/glue/tape/other)
>
>5) What specific material/mfr/part #?
>
>6) Do you use a fully loaded board for profiling?
>
>7) How often do you get to use a fully loaded board?
>
>8) Do you keep the board, with thermocouples attached, for later
>oven/profile validations?
>
>9) Do you use a partially loaded board with only large mass parts?
>
>10) Do you use a bare board only?
>
>11) What are your main concerns when profiling?
>
>12) Have you previously used other methods of attachment?
>
>13) If so, what type?
>
>14) What were your results?
>
>15) Do you work for a contract assembler or an OEM?
>
>16) Any other comments?
>
>
>Thanks again for your time and inputs....
>
>Mike McMonagle
>PCA Process Engineering Supervisor
>K*Tec Electronics
>1111 Gillingham Lane
>Sugar Land, TX  77478
>(281) 243-5639 Phone
>(281) 243-5539 Fax
>[log in to unmask]
>http://www.ktecelec.com


> -----Original Message-----
> From: Iain Braddock [SMTP:[log in to unmask]]
> Sent: 19 de Abril de 2000 13:19
> To:   [log in to unmask]
> Subject:      [TN] Thermocouple attachment, how & why?
>
> Cyber colleagues,
>
> I would like to get others' views on the following subject.
>
> When attempting to measure the thermal profile of a populated board
> through a forced convection reflow oven what is considered the best form
> of thermocouple attachment & why?
>
> I believe there are four general methods of attachment.
>
> 1)    T/c tip bonded to the lead/pad with something like a 2 pack epoxy
> quick drying, covering the tip.
>
> 2)    T/c tip touching lead/pad bedded onto a thermal compound paste
> with it covering it.
>
> 3)    T/c tip soldered to lead/pad.
>
> 4)    T/c embedded through board directly adjacent to lead/pad with
> compound covering tip.
>
>
> Option 1 -  Easy to apply and as the bonding agent isn't very thermally
> conductive perhaps less likely to be influenced by the higher air
> temperature in the chamber.
>
> Option 2 -  Easy to apply but perhaps influenced more with the air
> temperature although being sunk by the board.
>
> Option 3 -  Difficult to achieve as the tip isn't very receptive to SnPb
> solder.
>
> Option 4 -  Time consuming, destructive but perhaps less influenced than
> the others with air temperature.
>
> I appreciate that the temperature will also depend on where it is
> attached on the board power plane etc.
>
> Finally, but on a different but connected note, what would be the
> consequence if some of the joints had only just managed to get a few
> degrees above liquidus - reliability? Perhaps if you've read this one Mr
> Engelmaier it may be up your street?
>
> CIA Iain. << File: BDY.RTF >>

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