1 Introduction

High-accuracy temperature sensing is critical in many applications. Achieving this requires minimal thermal resistance between the measured object surface and the sensor package. High thermal resistance can cause a sensor's temperature reading to shift away from the actual object temperature and delay thermal response time. This application note details the thermal resistance measurements conducted on different sensor packages, such as the TMP116, TMP117, and TMP119, mounted on varying thicknesses of rigid PCB and flexible PCB.

The primary objective of these measurements was to understand how package selection and PCB design impact thermal performance. By comparing sensors with different thermal masses and configurations, we aimed to identify the setups that provide the quickest and most accurate thermal response. Sensors with lower thermal mass, like the TMP117 and TMP119 in a WCSP DSBGA package, showed significantly faster response times than those in WSON/QFN packages, highlighting the importance of reducing the IC thermal mass.

Additionally, flexible PCB were examined due to their potential for reducing overall thermal mass and enhancing thermal performance. Our experiments demonstrated that flexible PCB can achieve quicker and more accurate temperature readings than rigid PCB. This finding underscores the benefits of flexible PCB in applications where rapid thermal response is essential.

This document provides detailed results from these thermal resistance measurements and offers practical design tips for optimizing the thermal response of temperature sensors in various applications. By leveraging the insights from this study, designers and layout engineers can make informed decisions about sensor packaging and PCB design to achieve designed for thermal performance.