TMP121: Coefficient of Thermal Expansion (CTE) for Part Number TMP121AQDBVREP

David Weisenberg

Intellectual 510 points

Part Number: TMP121

Hi! I am doing a solder joint analysis for an assembly that uses a LOT of T.I. components.

Can you please tell me the coefficient of thermal expansion (CTE) of temperature sensor part number TMP121AQDBVREP ?

Thanks in advance for your help!

over 5 years ago

0 Josh Wyatt over 5 years ago

TI__Guru* 91206 points

Dear David -
we do not have this specified in the device datasheet - instead - we give the absolute max soldering temp there and have the material content listed here: www.ti.com/.../report

Additionally, we provide the recommended solder profile here: see SOT-23 www.ti.com/.../snoa292j.pdf and www.ti.com/.../snoa550e.pdf

0 David Weisenberg over 5 years ago in reply to Josh Wyatt

Intellectual 510 points

Actually -- the soldering information is not what I need. CTE is a function of the packaging. It's the kind of thing the packaging people would know about.

0 Josh Wyatt over 5 years ago in reply to David Weisenberg

TI__Guru* 91206 points

David -
I agree, CTE is a function of the materials of the package, and since you said you were doing a solder joint analysis, and we do not specify this specific parameter in the data sheet, I provided you with a link to the complete material content, the finish (in this case CuNiPdAu) and solder profile we recommend. Are you actually asking for the ANSI/J-STD-002-92 reference in a reliability report? If so, you can find this here: www.ti.com/.../sgzk020.pdf (my.ti.com login required (same as what you use to login to E2E)) - hope that is what you are looking for / helps you out here.

0 David Weisenberg over 5 years ago in reply to Josh Wyatt

Intellectual 510 points

I think it would be theoretically possible to derive a CTE from the material content and the part geometry, but that is well beyond my capabilities! I know that this information isn't in the datasheets, but when I have queried other parts manufacturers, they are usually able to give me a specific value. Some analytically estimate it, some test. I was hoping that T.I. had a specific CTE value determined for this part.

(If T.I. has never determined this value, I can take an educated guess. The CTE of leaded parts is usually in the neighborhood of the CTE of the leadframe material. But I was hoping for a more precise estimate.)

0 Wade Vonbergen over 5 years ago in reply to David Weisenberg

TI__Guru 62930 points

David,
All of the CTE's for the plastic encapsulated devices will have the same result as noted in this e2e post: e2e.ti.com/.../789140

The CTE of mold compounds is considered NDA and will take more effort to provide if necessary. For BLR and solder studies, I would expect that the mold compound has minimal to no influence compared to the leadframe.

Regards,
Wade

0 David Weisenberg over 5 years ago in reply to Wade Vonbergen

Intellectual 510 points

Exactly what I needed to know. Thanks for the help!

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TMP121: Coefficient of Thermal Expansion (CTE) for Part Number TMP121AQDBVREP