The Fabrication Technology Of High Precision Micro Tungsten Probe Ball Tips

At present,micro/nano coordinate measuring machines are widely used to measure the micro devices with high aspect ratio.As the core component of micro/nano coordinate measuring machine,micro probe ball tips directly determine the performance of micro/nano coordinate measuring machines.Therefore it is necessary to develop a monolithic micro probe ball tip with high precision and small size.The following works are done in this paper :1.The fabrication methods of the micro probe ball tips were summarized.Based on the principle of arc discharge and the phenomenon of liq uid surface tension,the end of the tungsten wire can be melted and formed into micro tungsten probe ball.The experimental device was also designed and built.2.The characteristics of arc discharge in argon and air were studied.The parameters for the taper processing of tungsten wire and the fabrication methods of micro tungsten probe ball tips in argon were preliminarily determined.3.The effects of different discharge parameters such as impulse voltage,discharge duration,pulse width,frequency and electrode gap on the geometric characteristics of the micro tungsten probe ball tips were studied.In this paper,the diameter,roundness,center offset and success rate of the probe ball are used to determine the quality of tungsten probe.And the optimal interval of each variable parameter was preliminarily obtained.4.The output response of the fabricating process was evaluated by the diameter,the roundness and the center offset of the tungsten probe balls.The smaller-the-better was also applied to analyse the influence of various factors on the characteristics of the tungsten probe balls.The optimization parameters are finally obtained.A micro tungsten probe ball with a diameter of 79 ?m,a roundness of 0.25 ?m m and a center offset of 0.5 ?m has been developed.5.The forming mechanism of probe balls was preliminarily discussed,and the forming principles of several typical probe balls were explained.Finally,the application of the microsphere tungsten probe was tested.