Friday, February 20, 2015

Quickly Identify and Characterize Thermal Measurement Points

Being an R&D electronics engineer, have you ever wondered if your first prototype works as designed? Using your notes or experience, you can theoretically derive where the most power is dissipated and identify the potential problem areas, but a flaw in the design where power is being consumed at an unexpected rate might go undetected. A thermal imager can quickly help to identify these problem areas. Then, you can characterize your design in different scenarios using DAQ system and thermocouples.

Quickly identify thermal measurement points with a thermal imager or a thermal camera

First, you need to identify the area that you want to monitor. In traditional electronics design, this means finding hotspots or areas where you have poor air flow. In other applications, such as building inspection, hot or cold spots may be area of concern. Using a thermal imager will quickly allow you to determine where to focus your efforts. Below are some samples of images and its respective thermal images that highlight areas that are relatively hotter. 

Figure 1: Picture of a printed circuit assembly (PCA) under test

Figure 2: Two thermal pictures of a PCA. Right image is a close-up portion of the left-hand portion of the PCA. 
Most thermal camera in the market will highlight the maximum and minimum temperature on the display, and some comes with the option to add spot measurements. The thermal images above shows some hotspots, allowing us to determine where to focus our efforts. To ensure you get an accurate measurement, remember to set the emissivity setting at the thermal imager to match your printed circuit board, or the material you are measuring. Emissivity of a material is its relative ability to emit infrared energy. As an example, the emissivity of normal FR4 PCB is 0.91. One other option is to spray your board with a spray-on high emissivity coating, such as boron nitride lubricant, that has an emissivity value of 1.

Making data acquisition temperature measurements

Once the points have been determined, a DAQ system can be used to further characterize the heat profile of your design. One of the first steps to characterizing your temperature is to choose the right temperature sensor. Common temperature sensors include thermocouples, Resistance Temperature Detectors (RTDs), thermistors, and IC sensors. Each has its own particular advantages for different applications.

Once you have decided on the type of device to use for temperature monitoring, you will need to mount the devices onto your board or structure. Once your system has been wired and mounted, you can do a long term monitoring of your design in various environmental conditions, under real-world conditions or in an environmental chamber.

Using a thermal imager, you can quickly identify thermal points that you want to monitor. With DAQ system and temperature sensors, you can make reliable, accurate and long-term temperature measurements to fully characterize your designs. With a thermal imager and a DAQ system, performing temperature measurements on your designs has never been easier. 

For more information on this application, click here to read on. 

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