Thermal imaging technology in printed circuit board inspection

The design and production of printed circuit boards (PCB) is an extremely delicate process, and it is fairly difficult to discover design imperfections or manufacturing defects in circuit boards. There might be such a time when you powered a freshly built PCB, only to find you’ve hit the current limit. Safely, you explore the board with your finger, but no parts are hot to the touch, and also, probing around with a multi-meter doesn’t pick up any unexpectedly low resistances, short circuits, or significant voltage drops. Besides, traditional optical methods are inadequate to track down the major faults.

Alternative inspection methods such as thermal imaging are highly required to spot PCB faults. thermal imagers can detect minute temperature differences across their view, allowing us to identify quickly any components that are consuming current because any parts of the board that draws current will generate heat and can be easily arrested by a thermal imager.

A PCB starts to heat up when being supplied with voltage because electric current flows through the board. PCB thermal fields can be determined and visualized by a thermal imager. With adequate knowledge of the thermal field, manufacturing defects could be detected early in the design process. Thermal imaging can be used to visualize the excessive heating of certain components caused by incorrect mounting, short circuits, or insufficient tin during soldering including the following uses:

1. Optimizing the chip routing

Designers could figure out the overall allocation of heat and add coolers and other components accordingly with the help of thermal imagers. When compiling the code for an FPGA, chip routing may be less than optimal. Temperature evolution in different regions of interest (ROI) can be displayed through FOTRIC AnalyzIR to discover excessive loads on some areas of a greater chip.

Historical time-temperature curves of a part with excessive load (Output from AnalyzIR)

3D temperature distribution can better visualize the heat anomaly (Output from AnalyzIR)

2. Shortening PCB development time

Thermal imaging shortens the PCB development time and enhances its design process. If the layout design is defective, a high current would flow through some areas of the PCB and generate excessive heat, which in turn makes the PCB unstable and shorten its service life. However, it is not easy to discover these design defec