Practical design, simulation, and prototype of a hot bar blade for printed circuit board soldering

Abstract According to production records and field tests in the cellular phone industry, the existing hot bar blade design has two defects: (1) temperature distributions along the edge of the hot bar blade are non-uniform during the heating and soldering processes; and (2) the blade cannot reach the desired temperature and temperature increase rate. The direct result of these problems is poor quality of the soldered printed circuit board. In this research, the heat transfer process along the blade edge during the heating and soldering processes was modeled using conduction and convection equations. The equations were solved based on the initial and boundary conditions from real production. The manufacturing process was simulated by using the finite element method. Simulation results have shown that in the heating process the temperature difference along the blade edge is up to 100°C for the existing blade design. The new design of the hot bar blade was based on the simulation and analysis results and then improved using computer-aided design. The simulation results have shown that the uniformity of the temperature distribution of the new blade has been improved greatly. The temperature distribution difference is less than 15°C in the heating process, and the temperature increase rate meets the technical requirement. Several prototypes of the newly designed hot bar blade were manufactured and tested on the cellular phone production line. The results have shown that measured data were in good accordance with simulation results, and the new design can improve product qualities and raise productivity. The proposed methods used in the modeling, simulation, design, and testing of the hot bar blade can also be applied to other similar processes.