"James Sweet" bravely wrote to "All" (26 Oct 04 05:20:19)
--- on the heady topic of " Testing solder joint"

JS From: "James Sweet"

JS "Grant" wrote in message
JS ups.com...
Hi all,

I have done some soldering on my gameboy advance and have created a dry
joint, I would like to know if is possible to test a solder joint using
a multimeter if so how and what make is recommended (I don't need
anything fancy).

Thanks
Grant


JS Just look at it, if it's dry it'll look dull. Don't use lead-free
JS solder if you can help it, that stuff is crap, even after years of
JS soldering I still can't make a nice joint with it.

It is possible to test the resistivity of the joint using a milli-ohm
meter. It's may be a hard to find gadget though so one could
alternately inject 1 ampere of current and measure the voltage drop
using the 200mV scale of a dmm. i.e. a 7mV reading equals 7milli-ohms.

The acceptable resistivity of the joint would depend on the amount of
expected current. Generally speaking anything below 50 milli-ohms
would be okay. However, for large currents I'd want less than 10
milli-ohms. i.e. 10 amperes at 10 milli-ohms is 100 milli watt.
An ideal 1 milli-ohm or less might not be easily achieved. However if
the component lead is bent flat over the conductive trace it may be
much closer to zero ohms than if left floating in solder as is common.

A*s*i*m*o*v

.... Power is obtained by current meeting resistance