Microcontroller Based SMT Reflow Oven Controller

Overview

The SMT reflow oven controller is based on H8/3687 microcontroller which can be used to transform a conventional infrared toaster oven into an effective reflow oven that performs thermal control.

Details

The project uses the 7-stage thermal profile controller EVB87 evaluation board with Basic Micro that provides an on-chip analog-to-digital converter, pushbuttons, enough supply of RAM & program memory, and LCD. The whole design would only require the addition of two small circuits including a driver for an external relay to turn ON and OFF the reflow oven and a thermocouple interface. The 3 types of cycles that can be performed by the SMT reflow oven controller include Preheat cycle, Reflow cycle, and Bake cycle.

The technology used in manufacturing for years was the surface mount technology (SMT) which became mandatory at present even for prototypes. High-speed designs will not work using large through-hole packages and there are several new components that are only available in SMT packages. Creating a reflow oven provides the possibility of having a good soldering. This project was cheaper compared to other reflow ovens which required very strictly controlled thermal profiles while limiting the stress to the components.