On Wednesday 27 February, the Section for Mechanics at Technical University of Denmark in Copenhagen, DTU, a half-day seminar on printed circuit board varnish. One of the section's institutions, Celcorr, specialises in research on the corrosion of electronics.
The seminar invited speakers from various research companies and companies selling materials, equipment and methods for protecting sensitive electronics. Tuomas Ollilainen, Tribotec's Product Manager for Silicone, was asked by Celcorrs Professor Rajan Ambat to come and talk about silicone-based circuit board coatings.
The seminar attracted around 65 participants from Sweden and Denmark. Representatives from companies such as Danfoss, Vestas, Bombardier and Grundfos were in the audience.
Interest in protecting electronics is growing steadily, and the big companies are joining the trend. In the past, designers in both Sweden and Denmark have focused a lot on IP ratings, i.e. the idea has been to make a seal around the electronics so that you do not have to paint or mould the electronics in any protective material. But as Jens Peter Krog from Grundfos proved in his presentation: all polymers let moisture through, it's just a matter of time. This means that even the highest IP rating, IP67, does not help more than briefly. The realisation of this has started to sink in with the industry quite recently.
Judging from the after-talk, many people were very satisfied with the information presented during the seminar. Although several of the speakers represented competing companies, there was no significant debate about the advantages or disadvantages of the various options. Everyone seemed to recognise that silicone provides very good protectionbut that it costs slightly more than acrylic paints, for example.
The only time things got a bit heated was when Tuomas Ollilainen argued that it was not necessary to wash the circuit boards before applying the silicone lacquer. The other representatives of protective materials agreed, but Professor Rajan Ambat added that their research shows that no material provides 100 % protection unless you wash off flux residues. However, to wash or not to wash is a rather controversial issue. DTU only washes with isopropanol, but many industrial washes also involve detergents, and there is a risk that detergent residues will remain on the cards, thus introducing a new problem when one wanted to get rid of another. At the same time, it can be noted that DTU has a very high level of methodology in its research, and it is possible that at that level differences can be found between washed and unwashed cards.
