Automated adaptive control of the reflow soldering of electronic assemblies

This paper describes a new technique for the monitoring and automated control of the reflow soldering process. The new technique combines state of the art infra-red (IR) sensor technology, coupled with application specific process control software, to provide a unique capability to both monitor actual product temperatures during the soldering process and to use this information to modify the process settings. The development of techniques to allow rapid variation of the heat transfer from the oven to the in-process Printed Circuit Assemblies (PCAs) allows the system to automatically adjust the soldering oven's process settings for each individual PCA passing through it. This product-by-product profiling facilitates the assurance of consistent thermal histories and also allows the oven to optimise its energy consumption to the demands of each product. Archiving of the reflow temperature profiles also provides full traceability to the reflow process. The incorporation of IR sensing technology also aids in determining/verifying the oven profile at the introduction of new PCA designs. This paper presents an overview of the construction and operation of the system and outlines the technical challenges that have been met and overcome.