The expanded and updated eBook “Rheology of Thermosets” is completed and available on the site. Check it out here
The updated “Dielectric Cure Monitoring” ebook will be released shortly followed by the “Polymers in Electronic Packaging” ebook.
I was attending the Electronic Components and Technology Conference (ECTC) last week. The ECTC is the largest conference dedicated to electronic packaging. The attendees ranged from “old salts” like me to grad students working on projects related to the many aspects of electronic packaging. During lunch one of the grad students at my table was asking about what skills should they have to be successful in electronic packaging. Interesting question. For anyone who has spent even a little bit of time in electronic packaging, the realization is quickly understood that many disciplines are required to develop new products and solve problems.
It got me thinking about my own path. I was an undergrad Mechanical Engineer and Materials Science major, but I also took multiple chemistry classes (including Organic Chemistry, really fun stuff!). In grad school at Northwestern, my major was Materials Science and Engineering with a specialty in polymers. Prior to our qualification exams, we had to demonstrate competency in 5 out of 7 areas in materials science (polymers, metals, ceramics, biomaterials, solid state physics, crystallography/diffraction, and electron microscopy).
During my Ph.D. research, I synthesized model polymers, characterized the chemical and physical properties, and measured the rheological properties. The goal of my work was to correlate the rheological behavior with the structure of the polymer (linear chains, short chain branching and long chain branches (3-arm, 4-arm, and dendrimer-like star polymers). When I was taking classes, I mostly focused on polymer chemistry, more organic chemistry, polymer physics, and polymer characterization.
I don’t know when or how it happened, since it was back in 1978, but I really got hooked on electron microscopy. We had to take classes in transmission electron microscopy (with the feared Prof. Mike Meshi) and I also took scanning electron microscopy. I thought it would be cool to become an expert in an area not at all related to polymers. So I signed up to be the TA for both the TEM and SEM courses. I learned as much as I could about these pretty useful electron beam methods. I just thought this stuff was really interesting. I know, I’m a “big nerd” but I love material science. But what I didn’t know…
My first IBM project thrust me into a huge problem with polymers used in complicated circuit boards. The boards were delaminating during soldering. Pretty simple, the epoxy resin in the circuit boards absorb moisture in the warm humid summer months, so get rid of the moisture by drying the boards, and no more delamination. Nope. Drying made the problem worse. I had access to world-class electron beam equipment in my department. We had two state-of-the-art SEM’s and an scanning electron microprobe (think of it as an SEM on steroids). We also had Auger electron spectroscopy, Electron Spectroscopy for Chemical Analysis (ESCA). To make a long story short, at about 8 PM one evening, sitting at the SEM and looking at the energy dispersive x-ray spectrum (EDS) of a delaminated circuit board, I found a peak that shouldn’t have been there. It was indicative of a contaminant that nobody had ever considered. I worked with my colleagues and used ESCA to confirm the chemical species. I did more quantitative measurements on the scanning electron microprobe using wavelength dispersive x-ray (WDS) analysis. Electron beam methods were the key in identifying the contaminant. The question was: how did that contaminant get into the circuit board?
I worked with the process engineers to conduct a very detailed process audit and found the source of the contamination. There was an aspect that was really puzzling. The circuit boards made at one production site delaminated. Circuit boards made at a different location didn’t delaminate. So why the difference? Turns out a chemical cleaner used at the site with large amounts of delamination was introducing the contaminant into the laminate. The chemical also was very effective at absorbing water, so when moisture diffused into the boards, it was absorbed by the contaminant right at the interface. Bingo, during soldering the moisture at the interface would explode and the boards would delaminate. Turns out that the site that were the circuit boards didn’t delaminate used a different cleaner that didn’t contaminate the interface (we verified with SEM and ESCA). We changed the cleaner and eliminated over $10 million in scrap the first year (big number back in 1982).
So let’s go back to the lunch discussion at ECTC with the grad student. Electronic packaging requires a wide range of skills and knowledge to be applied in an multidisciplinary manner to solve complex problems or develop new products. Having expertise in multiple areas will be very useful to scientists and engineers involved in electronic packaging. For all the students reading this post, obviously excel at your thesis work, but find another technical skill that excites you and develop deep expertise. Who knows when it will come in handy.
I jump started my IBM career using electron microscopy and I’m a polymer guy…
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