Résumé : |
Plastic molded and encapsulated electronic components are often exposed to extreme elements, especially in automotive applications where engine fluids, rain, snow, mud and road salts are part of everyday operation. These corrosive particles can quickly penetrate the component where encapsulant meets metal or at thermoplastic joints, and as a result, shorten part life.
But when Tri-Tech, LLC, of Mishawaka, Ind., won a contract to manufacture encapsulated coils for gas valves on buses powered by methane and propane, the company said it knew the components would be used on pressurized tanks as solenoids for the main shut-off valves, they needed to be extremely reliable.
Tri-Tech manufactures a wide array of encapsulated coils and solenoids for the automotive, applicance, medical and process control industries, including components for dot matrix printers and soda dispensing machines. "The gas valve solenoids would be exposed to moisture road salt and extreme temperatures, and they were vital to the system. So they needed a dependable, environmental seal", explaines Bille Everett, Tri-Tech's director of sales and engineering. "Through the operational heating and cooling of the coil, ambient air and water could be pulled through cracks and pump road salt directly into the windings.
"It would act almost like tooth decay", Everett said. "The copper and solder junctions would corrode, causing open circuit failures and deteriorating enough enamel insulation to cause shorts. |