J Koo,
But some JPese companies trend to use solder whose melting point is higher
the current one on PCBA to do the thermocouple attachment. They also use
bonding glue. Could you tell me the difference about temperature (oC) when
applied solder and bonding glue? Is it big?
For me, I think the most important thing is that do not let the wires of
thermocouple contact each other except at its tip. Otherwise, the result
will be the average values along the locations where the wires've contacted
each other. It's better to use Kapton tape as the shield attached on PCB
surface and put the bare thermocouple on.
The preferred diameter of thermocouple they are using is 0.05mm. It's very
convenient if you want to do profile for bga balls.
Tks,
Le Ai Quoc
----- Original Message -----
From: "Joyce Koo" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, October 22, 2004 10:54 PM
Subject: Re: [TN] A poll of sorts...concerning thermocouple attachment
> one word of caution: do not apply solder at the thermocouple tip. The
> resistance of the tip will change and give you false readings.
> jk
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of Jason Gregory
> Sent: Friday, October 22, 2004 11:45 AM
> To: [log in to unmask]
> Subject: Re: [TN] A poll of sorts...concerning thermocouple attachment
>
>
> Dr. Zapfardt? Glad it's Friday. :)
>
> Jason Gregory
> Manufacturing Engineer
> x5593
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of [log in to unmask]
> Sent: Friday, October 22, 2004 10:20 AM
> To: [log in to unmask]
> Subject: Re: [TN] A poll of sorts...concerning thermocouple attachment
>
>
> My first choice would be to attach TCs using either high-temp solder or
> conductive epoxy (after first removing the existing alloy at the
> connection). If
> you can commit a PCBA to profiling, this is the long-term way to go.
> Of course there are times when you cannot sacrifice a PCBA to the Profile
> Gods. Temprobes are good (we tested them a number of years ago) as long
as
> the
> point of contact is on the flat of the joint being probed. If you hit it
> at
> an angle, you can be off by as much as 10 deg C.
> Like Karen, I have had pretty good success with aluminum tape. Quick,
> cheap
> and easy and with very little addition of tolerance. The article on KICs
> website explains it pretty well.
> 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
>
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