Preheating and heat addition by LASER beam in hybrid LASER-ultrasonic welding
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Heating during welding in electronics is limited because of the high difference between the properties of the components that are in the close neighbourhood of the welding area. The temperature should not exceed 240 °C. In the classic processes of soldering, depending on the soldering alloy types, the heat is up to 300 °C. Such temperature is producing thermal degradation of the neighbouring polymers. New hybrid heating process is proposed within the paper. A double source laser-ultrasonic vibration could be used as thermal source. Because of the concentration of the heat source, the duration of the process is sensitively reduced in time (from minutes down to 5–10 s). More, applying the heat in two sequences, a preheating of the base material can be done and the result is a decreasing of the hardness with about 10–15 %, so a decreasing of the brittleness is happening. After the preheating, the processing heating is applied. The thermal field was analysed and specific mathematical models of the field were built. The temperature of the process was reduced down to about 130–150 °C. A comparison between laser heating and hybrid laser-ultrasonic heating, from the thermal field point of view, is presented within the paper.
KeywordsHybrid heating Thermal field Microjoining Gold wires
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