MIL-STD-750 TM2052 PIND TESTING
“UB” PACKAGED DEVICES
- INTRODUCTION: The “UB” packages are one of the smallest devices ever subjected to the PIND test. These devices measure just 0.12″L x 0.10″W x 0.05″H with an internal cavity of about 0.015″ resulting in a PIND test at >130Hz (per MIL-STD formula). Due to their small architecture and miniscule cavity it can be daunting to find loose particles inside.
- Three questions were posed:
- 1. What is the optimal vibration frequency? About 130Hz
- 2. Does increased mechanical shock improve detection? No
- 3. Does simultaneous mechanical shock improve detection? Yes
- Synopsys of Testing
- 24 each of the UB packages were subjected to PIND test from 80-150Hz vibration at 10Hz intervals. The 24 UB packages were divided in to two groups, one group of 12 were tested in ascending frequency and 12 in descending frequency. After 3 runs (testing at 3 different frequencies) the packages were allowed to rest under an ionizing fan for 18 hours. None of the devices showed a change in Pass/Fail of PIND. The number of packages tested was reduced to 10, 5 Fails (with low particle noise) and 5 Pass (no particle noise). All 10 devices were shocked at >5000Gs @ 0.1msec and randomized. The 10 packages were retested at 130Hz (highest voltage vs. frequency) with simultaneous shock and again with non-simultaneous shock. The simultaneous shock had 5 detections (1 below threshold) the non-simultaneous shock had only 3 detections.
- Note: A competing PIND manufacturer claims a longer shock pulse without simultaneous vibration improves detection. This claim has been proven false by the NBS in 1978 and again in 2018 by B&W. Newton’s 1st Law is still valid!