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How can I find a 1 um size vacancy under 150 um brass?

  1. Jul 4, 2016 #1
    I have soldered a pair of brass tape on the both side of a copper tape.
    The thickness of each metal tape is about 150 um(micrometer).
    The thickness of solder is about 2~20 um.
    I want to know what device can find the small vacancy of solder between the brass and the copper tape.
  2. jcsd
  3. Jul 5, 2016 #2


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    Depends on the area of the void . Very small voids will be difficult to detect by any method but larger voids that occur in normal soldered joints can be detected by a variety of standard NDT procedures . X ray and ultrasound detection are commonly used .

    With these very thin layers you might be able to locate larger voids by measuring the through thickness electrical resistance at numerous points and detecting local variations .
    Last edited: Jul 5, 2016
  4. Jul 9, 2016 #3


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    Curious to know why you need to know if there is a 1u void? Presumably it makes a difference to some something? so can you use that "something" to help locate it?
  5. Jul 11, 2016 #4


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    You should be able to use acoustic time domain reflectometry, or an ultrasonic thickness gauge. There will be a significant reflection from the acoustic impedance mismatch where there is air between the laminated metals.
  6. Jul 12, 2016 #5
    I want to prevent the void from being created in the solder.
  7. Jul 25, 2016 #6


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    Why does it matter? What will the void do? CWatters asked because if your application is X and you will get Y problem then in your test setup you could do a bit of X and try to detect Y. If you see a bit of Y then you have the void. That may not be true of your application but if it is then you have a good way of measuring it.

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