Low temperature optodic bonding for integration of micro optoelectronic components in polymer optronic systems

Large area, planar optronic systems based on flexible polymer substrates allow a reel-to-reel mass production, which is widely adopted in modern manufacturing. Polymer optronic systems are fully integrated with micro optical and optoelectronic components as light sources, detectors and sensors to establish highly functional sensor networks. To achieve economical production, low-cost polymer sheets are employed. Since they are mostly thermally sensitive, this requires a restricted thermal loading during processing. Furthermore, a short process time improves production efficiency, which plays a key role in manufacturing processes. Thus, in this contribution we introduce a new bare chip bonding technique using light instead of heat to meet both requirements. The technique is based on the conventional flip-chip die bonding process. Ultraviolet radiation curing adhesives are applied as bonding material, accordingly a sideway ultraviolet radiation source, a so-called optode, is designed. Before implementing the concept, the light distribution in the contact spot is simulated to examine the feasibility of the solution. Besides, we investigate two different UV lamps regarding induced thermal influence on polymer substrate to choose one to be employed in the optode. Process factors, irradiation intensity and irradiation time are studied. Based on these results, the mechanical and electrical reliability of the integrated components is finally evaluated.
 

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