Vacuum-Assisted Selective Adhesive Imprinting for Photonic Packaging of Complex MOEMS Devices: Assembly of Miniaturized Particle Sensor

In this paper we propose the selective adhesive bonding technique using contact imprinting from thin adhesive layers spin-coated on the sacrificial polymer foils. The contact imprinting process is assisted with vacuum. We propose three different methods in order to improve the selectivity of the adhesive application, control the adhesive thickness and reduce the pull-off adhesive force and prevent die sticking. We apply these methods in assembly of a miniaturized optical particle counter confronted with several strict assembly requirements, such as selective bonding with small feature size ( < 200mu text{m} ), minimal adhesive thickness ( < 15mu text{m} ), precise out-of plane tolerances, low adhesive squeeze-out and airtight and hermetically sealed packaging. A successful contact imprinting was demonstrated with ratio of vacuum tool area to adhesive contact area of 1:20. Die-bonding with minimal feature size of 70mu text{m} and trench size of 25mu text{m} was demonstrated.