Thermocouple Tactics: A Comparative Study of Attachment Methods

ABSTRACT Achieving high-quality printed circuit board (PCB) assemblies requires precise control of the time-temperature profile during reflow soldering. This profile must align with the specifications of the materials and components and remain consistent as the product moves through the oven. Inaccurate control of this profile can result in defects, costlyrework and scrap, making reliable, repeatable and accurate temperature monitoring and control critical during the reflow soldering process. Time-temperature profiling typically involves attaching thermocouples to a sample PCB and passing it through a reflow process to monitor temperatures at key points. However, the reliability, repeatability and accuracy of these measurements depend on the method used to attach the thermocouples. This paper presents findings from experiments conducted at the Rochester Institute of Technology (RIT) to evaluate common methods of attaching thermocouples to modern high-density (HDI) circuit boards. The objective was to compare these methods and identify the most effective techniques for achieving reliable, repeatable and accurate time-temperature measurements. The study explores different attachment methods, including polyimide tape, aluminum tape, high-temperature solder, and two types of thermally conductive adhesive.