Research On The Equipment And Technology Of Ultrasonic-thermocompression Welding For Enamelled Wire

Enamelled wire has been widely used in the field of aerospace, automobile making and electron components as a part or the conductive medium between each other. In these applications, most of the time it involves the issue of the connection between the end of enamelled wire and metal terminal (such as insert, needles, foil, etc.). Traditional connection methods, take welding quality, welding efficiency and welding cost for example, are often unable to balance multiple aspects to obtain comprehensive benefits. This makes connection for enamelled wire have always been one of big industrial problems for a long time.This paper comprehensively analyzed the welding difficulties of the enamelled wire, proposed ultrasonic-thermocompression welding for enamelled wire which can connect the enamelled wire to metal terminal firmly in just one producing process without previously remove the insulation film of enamelled wire.Designed the test platform for welding enamelled wire, selected the suited power supply and the self-hot indenter. Especially designed the servo pressure institutions and half wave ultrasonic vibration system, and confirmed the reliability of half wave ultrasonic vibration system through modal analysis by Ansys.Taking advantage of the test platform for welding enamelled wire, successfully realized the connection between enamelled wire (diameter is0.2mm) and phosphorus copper foil (thickness is0.2mm), researched the impact of welding current, welding time and welding pressure, and ultrasonic power on tensile strength and appearance quality of welding spot through the single factor test and orthogonal test.Analyzed the degree of influence of various process parameters on tensile strength and appearance quality under experimental conditions, finally summarized the optimal parameters of the process for the two selected materials, provided data support for further experiment and guidance for practical production to a certain extent.When the welding current is426A, welding time is26ms, welding pressure is70OZ, diameter of wire is0.2mm and the thickness of phosphorus copper foil is0.2mm, A comparative study of the impact of ultrasonic vibrate on tensile strength and appearance quality of welding spot was carried out under the separated conditions with ultrasound or not. Combining the theory of ultrasonic bonding, the influence of ultrasonic energy on the material deformation, the metal atoms diffusion mechanism on the bonding interface, made deep analysis of the differences between two kinds of welding spot through metallographic observation and EDS of sample cross section. Represented the formation process of welding spot, and then explore the role of ultrasound in ultrasonic-thermocompression welding process for enamelled wire and phosphorus copper foil, demonstrated the essence of the welding process is a solid connection, ultrasound can promote the diffusion of the metal atoms on the bonding interface, therefore, it can increase the tensile strength, but diffusion is not the necessary factor for the formation of connection between enamelled wire and phosphorus copper foil.