Solder jetting - a versatile packaging and assembly technology for hybrid photonics and optoelectronical systems
Solder Jetting, typically used to create variable bumps in flip chip applications, can be adapted to be a versatile assembly and packaging technology for hybrid photonics and MEMS. Instead of applying the solder bumps prior to the chip placement the approach that is reported here handles the jetting device by means of a 6-axis robot independently from the complex assembly environment necessary for hybrid photonic and MEMS mounting and with the ability to reach even complex and 3D-shaped joining geometries. After placing the respective components within the system to be assembled and after reaching the desired alignment state that often require micron and submicron accuracy the jetted solder volume creates the joint between the component and the system plattform. The metallic solder alloy is advantageous over standard adhesives due to better temperature, radiation and long term stability, making it favourable e.g. for high power applications, but it also serves for electrically and thermally conducting joints, thus with thermal management functionality. It is able to form joints between a wide variety of materials for components and system platform, if the prerequisite of metallized and wettable joining surfaces is fulfilled. But additionally our investigations show that by proper parameterization micron and submicron alignment stability for the component to be joined can be maintained during the application and resolidification of the liquidly applied solder. For lens and fiber joining numbers of radial alignment stability better than 1.5±0.5 µm are reported when using 760 µm diameter SnAgCu-solder spheres. Thus the proposed technology is a new and flexible tool for not only connecting, but also precisely mounting components within a hybrid system.