Laser-basiertes Löten - Fügetechnologie für den hermetischen Verschluss miniaturisierter medizintechnischer Geräte

New optical designs and miniaturized optical components, as well as material-fit joining techniques allow for the downsizing of biomedical devices such as endoscopic systems. Laser-based Solderjet Bumping allows for hermetical sealing by means of localized solder joints. These material-fit, metal-based joints provide a longterm stable alternative to polymeric adhesives and permit for processing in steam autoclaves. The selection from a wide variety of solder alloys ranging from the low-melting BiSn alloy over lead-free tin-based solders to the biocompatible high-melting eutectic AuSn solder alloy, as well as the parametrization of the process allow for precise adjustment to different wetting behavior and complex shaped joining geometries. Miniaturized endoscope tips are demonstrated with windows made of saphire (diameter 1.2 mm) soldered to endoscope tips made of stainless steel by subsequent placement of eutectic AuSn solder spheres (diameter 100 ?m) using the Solderjet Bumping technique. Measurement of leakage rate with helium showed results better than 10-8 mbar*l/s to 4*10-9 mbar*l/s. Pressure test (5 bar, nitrogen) and four sterilization cycles in an autoclave (134 °C, 2.1 bar, steam) showed no detectable change during optical inspection and measurement of leakage rate