Quoted from Richard_Brazil:
".....The internaut pointed out other problems such as breakdowns in TCAS, transponders and radios, which have been happening since 2005, the use of non-electricity-conducting silicone in the transponder's connecting terminals, which may interfere with the equipment's functioning; and incorrect information on onboard computers. Marco Maia affirmed that these are new pieces of information, which will be analyzed technically. "What I can affirm to you is that the technical conditions, of the Federal Police as much as the Air Force, are adequate for the analysis of this information. Many of these analysis are being done or were performed in the United States or in Canada....."
I have some experience with silicon (not) being used in circuits when I worked as an engineer at a major telecom company.
Because of serious problems with silicon very slowly migrating to contacts thus resulting in failures of mechanical contacts in switches and connectors due to detoriating contacts, we were forced in public telephone equipment to not used silicon based pastes.
It gave me major headaches then to find and confirm non-silicon replacements.
Major telephone companies had serious problems with silicon based products.
It is possible that the avionics industry has not caught-up to the telecom industry; or the newer designers have forgotten (or other) about the problems with silicon pastes.
.