SIR testing reveals, among other things, a PC board's tendency to grow dendrites. Dendrites can form into short circuits over time as a result of imperfections in soldering materials or in the soldering process. The finer pitch of a PC board, the higher the probability that a dendrite may form. When fine pitch PC boards are used in critical applications such as aviation systems or medical electronics, dendrite formation can put human lives at risk.
Dendrites are difficult to detect because they can spontaneously grow and spontaneously disappear, causing intermittent short circuits which are almost impossible to correct. This is a key challenge which Trace East's new Auto-SIR helps to solve. While typical SIR testing takes measurements every 24 hours or 96 hours, the Auto-SIR can measure surface installation as frequently as every 20 minutes, on as many as 256 individual channels. The result is near real-time testing which can detect virtually any dendrite formation, no matter how briefly it might last.
Trace East's Auto-SIR can perform a variety of standard IPC and Bellcore tests and can read 2-point test patterns (typical of IPC-B-24 boards, Y-patterns, and production boards). The tester can also be set up for custom-defined testing procedures using voltages of either polarity, ranging from 5 to 500 volts (with 2-or 5-point test patterns), and virtually any frequency of insulation resistance reading.
Although having an instrument like the Concoat Auto-SIR is an essential part of advanced SIR testing, another important component involves preparation of the test samples so that measurements are accurate and representative of typical specimens to be found in a production setting. Trace East has expertise in sample preparation to ensure that test results accurately reflect the true nature of the product's integrity.