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Rework, BGA, Temperature measurement

How can you measure a BGA component thermal profile without destroying the BGA component in the process?

The Rochester Institute of Technology recently conducted a comprehensive study to measure whether there was any correlation between the temperature underneath a BGA component using a flat bead thermocouple, and a thermocouple attached on top of the component using aluminum tape.

A correlation was indeed found, which means that electronic assemblers can attach a thermocouple on top of the BGA component and use an offset to determine the temperature underneath. When attaching the thermocouple with aluminum tape, which can be peeled off afterwards, you can profile the BGA in a non destructive way.

The offset is dependent on each particular application. A free Excel calculator is available from KIC which enables a user to identify the offset specific to the application.

 

 

 

 

 

 

 

 

 

 

For more information see:     Temperature Difference Calculator By KIC

Originally published in IPC Outlook

4 Responses to Rework, BGA, Temperature measurement

  1. I’ve heard tales of this (from KIC) but have never been able to find someone who has actually put it into practice. I would be a little dubious on that KIC calculator as well. The output is “theoretical”. There are MANY factors that determine the temperature reading at a [BGA] solder joint and personally I am not comfortable with HAL 9000 giving me advice.
    When developing reflow profiles we suggest that you rely on industry standard methods. Bore hole, insert thermal couple, secure with aluminum tape. …that way there is no guessing.
    The aerospace auditors would have a heart attack over this subject.

  2. I’m going to ask KIC about this, while at SMTAI 2012

  3. I took a printout of this page and was poised to understand how thing fit together, but couldn’t find KIC at SMTAI 2012.

    So, this has pissed me off. I’m going to find someone at KIC that can give us a reasonable response. stay tuned.

  4. Jack pot!!! The KIC folks at IPC APEX 2012 were very helpful.

    They said [words to effect] … You’re correct. You need to determine if this approach works for you. They have lots of customers using the method and are happy with it. Here is the method they use to evaluate the method: http://kicthermal.com/paper-a-articles/evaluating-the-accuracy-of-a-non-destructive-thermocouple-attach-method-for-area-array-package-profiling

    I have a contact at KIC who will be more that happy to help you understand this better, if you want to move forward.

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