PROBLEM

Traditionally, engineers use in-circuit testers (ICT) for manufacturing assembly testing. However, with the move to advanced packaging technologies (such as BGAs), the ability of in- circuit testers to give full nodal access is greatly impaired.

In functional test, our customers are finding ICT escapes. For example, due to the vacuum pressure that ICTs use, some opens are closed, thus passing the ICT test, but failing a functional test.

In an environmental chamber, where there is limited space and large swings in temperature and voltage, ICTs are not easily hooked up to test a board or system. As a result, you can have problems identifying what caused a failure while the system was being stressed.

SOLUTIONS

ASSET boundary-scan tools solve these problems by giving engineers virtual access to the pins of the chip, so that they can easily perform necessary tests.

Using boundary scan in functional test can capture ICT escapes before a lot of time is spent in the functional test process. Boundary scan can also be used to test the assembly of boards and daughter cards to ensure correct construction before functional test begins.

Because running the tools only requires hooking the board or system to a PC with conventional data cables, engineers can easily monitor units in a test chamber. This allows you to capture information at the time of failure, to help you troubleshoot.

It is worth noting that many of our customers use boundary-scan tools in manufacturing to complement the functionality of an ICT. This becomes particularly helpful when the ICT is used not only for test, but also for other functions (such as ISP). This extra workload slows the ICT. At this point, it makes sense to consider offloading some of the work of the ICT to a PC-based boundary-scan manufacturing system. This increases manufacturing capacity with a smaller investment.

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