A Novel On-board Temperature Monitoring Approach in the Reflow Soldering Process

The goal of this paper is to monitor in-process on-board data as a means of indicating product quality and to be able to respond quickly to unexpected process disturbances. Due to pending environmental legislation and market requirements, lead-free soldering is widely used by the electronics industry. As the margin between the higher melting temperatures of lead-free solders and the heat-resistant temperatures of electronic components becomes narrower than lead solders, a more precise control of the temperature is required. Traditionally, the control processes of the on-board temperature are open loop because it is difficult to monitor the temperature on a PCB board. In this paper, we establish a method to determine the real process temperatures at any point on a PCB board in the furnace. We develop the method based on support vector machines (SVM) with multiple-input single-output strategies to learn relationship between the temperatures near the PCB board and the on-board temperature. The method is the only one which has been commercially utilized to predict the on-board temperature because of its low cost and high accuracy