Analytical Techniques in Electronics Manufacturing

IC, ROSE, and SIR Testing.”
– Adam Klett

Q: If I see a spike in an ion in an IC report, how can I determine the source?

A: This can be a tough problem to solve, especially if the problem appears to be random or arises with no apparent cause. The best way to detect the source of ionic contamination is to walk the production line, starting with the reception and looking at every step. If a process has changed, that is a great place to start. Also, keep in mind that contamination can come from anywhere, including the bare boards or parts, and even human contamination as well.

Q: What is the maximum allowed ROSE measurement to still be considered clean?

A: The IPC recently changed its stance on this, and there is no longer a universal number to indicate clean. Your boards must be shown to be clean using a different technique, like SIR, and then correlated to ROSE data. A process that has been qualified can be monitored using SPC techniques, and the upper and lower limits will be defined during that process.

Q: Why do some SIR patterns look so noisy and others so flat?

A: There are a few sources of noisy SIR data. The first and most important reason is a dirty board. Many times, sporadic and noisy SIR data can be attributed to contamination on the board. However, if that is not the case, there could be an issue with the experimental setup. For example, condensation dripping on the test coupons from inside the test chamber can cause spikes in the data.