It’s tricky to test CMOS image sensors on a wafer-size scale due to the challenges of creating uniform illumination over a large area. In pursuit of this, Presto Engineering has developed a custom, computer-controlled solution that illuminates sections of the wafer in turn. Integrating the results enables the whole wafer to be tested automatically for an array of large sensors or even sensors that are right up to the size of an entire 12-inch wafer, according to the firm.
Applications of larger image sensors are found in medical imaging and aerospace that can require whole wafer-sized, image sensors and are transitioning from CCD to CMOS solutions. Similarly, security and military applications require larger, better sensors to provide the resolution required to provide clear sharp images, as well as other 4K resolution cameras.
“An entire wafer can be tested in a laboratory using a similar method,” explained Martin Kingdon, Presto Engineering’s VP of Sales. “However laboratories are not geared up for fast commercial testing so we designed our own solution to test any size wafer. Importantly, we can do this in small to medium sized test runs here in Europe at our Class 10K cleanroom facility in Meyreuil, France, near Aix-en-Provence. We believe that we are probably the only such commercial test service to be available in Europe.”
According to the announcement, “Presto’s Teradyne IP750Ex based test solution provides a large (80x100mm), uniform (+/-2%), high-intensity illumination field up to 10K Lux at a range of color temperatures. Built-in IR filtering prevents sensor damage. Its ability create a customized test solution for complex devices (as large as 32M pixels at speeds up to 200MHz) on up to 12-inch wafers enables fast ramps without compromising cost-of-test.”
More information: www.presto-eng.com