About Micro Thermal Mapping

How does an Infrascope work?

The Infrascope uses a CCD type detector comprised of exotic infrared sensitive materials to detect thermal radiation from the part-under-test. Since the part features are very small the Infrascope incorporates microscope objectives, but since the wavelength is infrared, the objectives are custom made with infrared transmissive materials such as silicon, germanium, sapphire and zinc selenide. Most of the contrast in an unprocessed infrared image of a circuit is not due to temperature. Rather, in an unprocessed image, differences in emissivity create the most contrast. Emissivity is a material property that effects how well and efficiently the material emits photons. QFI uses patented algorithms and proprietary software to measure and compensate for the emissivity of the material being tested in order to generate an accurate, calibrated thermal image. In fact, QFI is the only supplier of microthermal imagers who compensates for emissivity and calibrates for accurate temperature measurement at each and every image pixel, and the Infrascope™ does it in seconds.

Step 1 & 2	Step 3
Convenient Real Time B & W Image for Focusing and Navigation.	Instantly Computed Each-Pixel Emissivity Removes Misleading Material Signa-
Step 4	Step 5
Unpowered Temperature Shows the Advantage of Emissivity Correction.	Power Applied—The Hot Spot is Clearly Visible.
These images are from the backside.at 5x magnification. The sample was supplied by Philips Research, Eindhoven, through the courtesy of Mssrs. Martijn Goossens and Victor Zieren. The sample is decapsulated on both sides. The process is six-metal-layer (copper), on a 10 Ohm.cm p-epi silicon substrate, thinned to 102 um.

The Details

Steps 1 & 2 - the Infrascope collects a radiance image at each of two distinct material temperatures.

Step 3 - the Infrascope, using patented and proprietary algorithms, computes the emissivity of the material from the two radiance images at each and every pixel.

Step 4 - the Infrascope captures another radiance image at a 3 rd material temperature to verify that the corrections and calibrations are accurate and that the part has not be bumped or moved.

Step 5 - the part to be tested is powered and the Infrascope captures an accurate, calibrated temperature image. The user easily determines the exact temperature at any point by color or by simply positioning the mouse arrow over the desired point and reading the desired temperature. This technique saves literally hundreds of hours over non-infrared techniques and it doesn't damage or affect the part in any way.