Schutzvorrichtung für Telekommunikationsanlagen

A surge protection device to protect telecommunication equipment coupled to telephone lines is shown having in a first embodiment three cells with each cell having a semiconductor element with a reverse breakdown PN junction mounted on a heat sink. The device includes a lead frame having a first pair of leads formed with a platform raised out of the plane of the remainder of the lead frame to provide suitable clearance relative to the semiconducting elements and each platform has a finger extending downwardly into engagement with a top electrode of a respective semiconducting element and is soldered thereto. A second lead lies in the plane of the lead frame and is soldered to a first heat sink plate mounting two semiconducting elements and another finger extending from one of the platforms is soldered to a second heat sink plate mounting the third semiconducting element. The heat sinks, semiconducting elements and portions of the leads are encapsulated in thermally conductive, electrically insulative epoxy. The device, when subjected to excessive current and voltage conditions, is adapted to fail closed. A second embodiment has two cells mounted on a single heat sink plate mounted in the same manner as in the first embodiment.