Stoneridge Electronics has long been a leading supplier to the heavy vehicle industry. It manufactures gauge panels for trucks and buses, for customers such as Mercedes, Volvo Trucks, Scania, etc. In the mid-1990s, new laws were introduced in Sweden that regulated how much solvent an individual company could use and release into the environment. Stoneridge Electronics in Örebro had been using a solvent-based circuit board lacquer with good performance in its production for several years. Because the production volumes were high, a lot of lacquer was required, which meant that solvent emissions were high. Even too high, according to the Environmental Office in Örebro, which put a lot of pressure on Stoneridge to switch to a more environmentally friendly circuit board lacquer.
Several paints are tested
A long and large project was launched to find alternative circuit board coatings. It was not easy, because the requirements for protection were high while the environmental impact had to be minimised. In total, Stoneridge Electronics tested four alternative coatings between 1999 and 2002, both internally and at external test centres, using blind tests to ensure that the results were as objective as possible. At this time, Tribotec had introduced the TSE 3991 CU silicone coating to the Swedish market, which Stoneridge was interested in testing. TSE 3991 CU is completely solvent-free and the technical data provided was very promising. Among other things, the surface insulation resistance was very high, and the paint cured at room temperature in a relatively short time.
Tribotec's winning solution also proved to save time
After three years of careful research, the TSE 3991 CU was chosen as the best option, thanks in part to its superior protection against condensed moisture. This was important because a lorry can be left standing for long periods in high humidity. At the same time, it was realised that the slow and expensive process of washing the circuit boards could be completely removed from the production line with the new coating. Unlike the previous coating, TSE 3991 CU showed perfect adhesion even without washing.
