Effect of Servo-Pressurized Mode on Soldering Process Characteristics of Micro-Parts

Abstract

To solve the problems of high pressure fluctuations and uncontrollable process pressure in the traditional pneumatic pressurized hot-bar solder welding process, a servo-pressurized system with high dynamic pressure and displacement responses was designed during this study using a servo motor. Focusing on the connection requirements between narrow-gap coaxial cables and printed circuit boards, the overall scheme of the system was designed, the dynamic characteristics of the mechanical structure of the system were analyzed, the hardware and software design processes for the control system were described, and a stage-type pressure-following motion control scheme for the hot bar suitable for solder-forming control was proposed. By conducting solder welding tests on narrow-gap coaxial cables with and without the control scheme, the welding process characteristics and joint qualities after welding were analyzed. The results show that when using the control scheme for solder welding, the welding pressure changes during the solder welding process trended first from a rapid increase to a slow decrease, then to a rapid decrease, to a slow decrease, and finally to a near zero value. “Soft contact” pressurization between the hot bar and the welded workpieces was achieved, the pressure fluctuations were reduced, and better surface and higher strengths were obtained for the welded joints.

Keywords

• Hot-bar soldering
• servo-pressurized system
• stage-type pressure-following
• solder welding
• process characteristics analysis