In circuit testing (ICT)

In-circuit testing has been used for many years to verify the electrical integrity of printed circuit boards. Traditional ICT methods use a 'bed-of-nails' fixture to obtain access to the various electrical networks to be tested on the board. Such testing makes it possible to check electrical connections, to locate potential short circuits and to evaluate component values and joint functionality. Successful ICT testing is reliant on the ability to make good quality electrical contacts between the board and the test fixture.

Lead-Free solders are generally harder than tin-lead alloys, which means they can be harder to penetrate with the tip of the test probe. This may require more force to applied on the board in order to achieve a good contact. Increasing the force increases the deformation of the board which can cause quality and reliability problems. The use of increased force also reduces the operational life of the test probes and in turn increases costs. Also, flux residue from some Lead-Free solders may be harder and more difficult to penetrate than for tin-lead solders because of the use of elevated soldering temperatures during soldering.

It is important that all the issues are understood if valid ICT test results are to be obtained with Lead-Free solders.