Polymer use in micro-devices, especially in the medical industry has been rapidly increasing. During assembly of micro-devices it is desirable to produce weld joints that are about 100 μm in width. This paper reviews the use of fiber coupled laser diodes in conjunction with special lenses to produce spot sizes between 25 and 50 μm in diameter for through transmission infrared welding technique. Studies were completed to evaluate the effect of travel speed, power density and pressure on weld quality for polycarbonate and polystyrene. It was found that process parameters are extremely critical in producing constent welds. In addition, new testing techniques had to be developed to allow quantitative measurements to be made on weld strength due to relatively small weld area. Micrographs of the resulting welds revealed evidence of ablation at high heat inputs. Finite element analysis of the mechanical tests showed that the localized weld strength approached the yield strength of polycarbonate.
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