how to test for cold soldering?

[trout00]

this may be off topics.
Does anybody has a good test/check for cold soldering, visual inspection is not good enough?

Any idea is appreciated.

[Jonnie_5]

Cold joints are usually only checked visually, looking for the dull griany color or rippling/pitting in the solder. I guess you could try using a DMM to check the resistance and see if a poor/loose connection is being made. It's usually best to remove the suspected connection's solder and just re-solder it.

[chutla]

The DMM test is good, if you can wiggle or stress the connection while measuring the resistance. It's always best to avoid cold solder connections in the first place. Never never EVER blow on a solder connection to cool it off faster. This is a surefire guarantee of a cold connection. Also, avoid moving the connection until the joint is cool. Patience is always the key to good soldering.

Eric

[RobCole]

One of the better tests is temperature shock. Move the sample from -40C to +40C and back again with enough time in between the moves for the equipment to reach that temperature. If there are cold solder joints then there is a very high probability that the solder will actually break the connection. I used to do this testing for a living and have seen more than a few failures this way. Even if contact is not lost through the solder connection, visual inspection becomes much easier as the bad connection will be more obvious. Using red or blue light filters as you inspect the board can also be quite helpful.

Rob

[Jonnie_5]

Very cool!

[Scott Seidman]

chutla wrote in news:506500000005000000065B0100-1075935269000
@exchange.ni.com:

> The DMM test is good, if you can wiggle or stress the connection while
> measuring the resistance. It's always best to avoid cold solder
> connections in the first place. Never never EVER blow on a solder
> connection to cool it off faster. This is a surefire guarantee of a
> cold connection. Also, avoid moving the connection until the joint is
> cool. Patience is always the key to good soldering.
>
> Eric

As long as you're at it, heat the joint, not the solder, and tin all your
wires where practical.

Scott