What tests are needed to check a part in series production?
Depending on the requirements, various test methods and procedures are used during series production. DAU has its own testing laboratory and can run a variety of tests for its own products. We summarize the most important test procedures below.
Infrared Camera/Automated Image Analysis
An automated image analysis can be created with a thermal imaging camera. For this purpose, the cooling in the water cooler is visualized using a permanently installed infrared camera. The thermal imaging camera, which integrates evaluation electronics and image processing, captures a high spatial resolution and an exact temperature resolution of 0.5 °C. The clear advantage is consistent and reliable product quality with fault detection that does not require human intervention.
Rth & dP Liquid Cooling Testing
This method tests the thermal resistance and hydraulic pressure loss of liquid-cooled cold plates. For this purpose, DAU's Solution Team uses various coolants such as water, ethylene, or glycol. The test bench automatically records data and can also be used in combination with the IGBT test bench.
Helium Leak Testing
With our helium leak test bench, we examine the heat sinks for damage. Helium helps to find leaks more easily. The test is conducted with a so-called pressure probe. Helium leak testing is a highly sensitive test bench with a leak rate of up to 10-6 mbar.l/s.
With the ultrasonic measuring device, we use an echo meter for ultrasonic measurement of the wall thickness. The measurable range of wall thickness is 1.2 to 250 mm. Ultrasonic testing is used for easy and accurate measurements in easily accessible locations. For this purpose, a probe is placed on the material, the cooling plate, and the wall thickness is measured with an ultrasonic signal.
With the Zeiss 3D coordinate measuring machine (CMM), DAU can guarantee the stipulated dimensional requirements (drilling pattern for mounting high-performance electronics) during initial parts testing. In this way, we can immediately identify and avoid production errors. The heat sink is measured to an accuracy of +/- 0.8 μm. This also allows measurement of many small characteristics, which is not only more efficient, but also reduces production costs.
2D Surface Measurement
The correct surface roughness of a heat sink significantly influences its functional behavior and thus contributes to meeting the component’s thermal requirements. That is why we measure the roughness of the surfaces of our heat sinks (largest peak-to-valley difference — Rz, average roughness — Ra) with optical measuring devices.
Mechanical Testing/Fin Pull-Out Test
The quality of the bonding of fins in an air-cooled heat sink is checked using the pull-out test bench; the required force is determined by pulling fins out of the profile.