Development of a laser-based process to produce a hermetically sealed contacting interface for the encapsulation of temperature-sensitive electronic components

In the construction of hermetically sealed encapsulations, feedthroughs are commonly required as contacting interfaces. The so-called GTMS (glass-to-metal seal) feedthroughs are often used in the field of sensor technology, acting as an interface between sensor unit and evaluation electronics. GTMS feedthroughs, consisting of a metal mount, a glass body, and contacts, transfer electricity, electrical, or optical signals through a glass-based barrier while protecting the inside of a sensor from the ingress of dust, moisture, or gases. They are mainly used in humidity, temperature, pressure, flow, and vacuum sensors and are actually produced in a furnace process in which the entire components are heated to the melting temperature (>400 °C) of the glass body. Sufficient heat must be applied to reduce the viscosity of the glass body to ensure a reliable wetting of mount and contacts. If temperature-sensitive components are involved, a furnace process is not suitable as the high temperatures damage these components. In this case, a technology with localized energy input is required. A laser-based process enables the reduction of the thermal load. Therefore, investigations on the manufacture of compressed GTMS feedthroughs for multilayer low temperature cofired ceramic with a diode laser have been performed, which are described in the following paper. Depending on the irradiation energy, the melting and wetting behavior of the glass body is determined. Results on the influence of the process parameters on the heat input and the thermal load of the components are discussed and quality-relevant properties such as helium tightness and burst pressure resistance of the laser-produced feedthroughs are evaluated.