Ion Chromatography vs IC-MS

Since the 1950’s, electronic assembly and manufacturing has changed at a dramatic pace. And whenever we have a big change, innovation is bound to follow.

One such change was the Clean Air Act of 1987. Before this, we never needed failure analysis tools as we do today. With the Clean Air Act, rosin and ozone depleting cleaning methods that had been used for decades on high-reliability technology were banned. The original method of leaving the rosin to seal everything in like varnish typically meant dendrite growth was not an issue. But with rosin no longer used and cleaning solvents out of the picture, this major disruption spurred a transition to the no-clean assembly materials (low or no-solid fluxes) that we see today.

With a no-clean process, the likelihood of circuit performance issues–dendritic growth, electrical leakage, and insulative residues–were and are far more common.

At the same time, constant progress toward smaller, denser, and more sensitive circuits invariably resulted in entrapped flux and electrical leakage issues becoming more prevalent. And not just more prevalent, but more difficult to analyze and dissect.

The good news: this series of changes and increased risk has led to new and improved failure analysis.

One such failure analysis method is Ion Chromatography. This technique utilizes conductivity and separation to detect individual ions in a liquid sample. In minutes, we can separate ionic and organic residues to get a known response, then compare that to a control. It’s an excellent solution for pinpointing the source of contamination related issues in reliability.

Although ion chromatography is excellent at separating and detecting ionic sources of contamination, the myriad flux formulations in use today utilize a wide variety of weak organic acids and other ionic ingredients. Sometimes coelution occurs (two or more ions with the same conductivity) or we need additional information (e.g., IC chromatogram exhibits unexpected peaks, identifying specific flux formulas).

When this happens, it becomes difficult to separate those ions and use Ion Chromatography to study them.

That’s where Ion Chromatography-Mass Spectroscopy comes in. Similar to Ion Chromatography, we gain insight into what is causing the electronic failure. With IC-MS, however, it’s at a much more detailed level. The addition of a quad pole mass spectrometer allows separation by conductivity and molecular weight. This allows for much greater separation of coeluting ions and allows identification of myriad weak-organic acid species–and providing valuable insights into the source(s) of chemical contamination on electronic assemblies.

Reliability is never a guarantee, especially as technology and laws change. It is up to us to learn, innovate, understand, and ultimately, get to the root of the problem.