1. Sensor probing (Summary)
Mini-production Sensors
25 from Peregia
Been used in previous module builds
Biased sample of sensors
4 had higher current in sensor IV probe
3 used in modules
1 caused chip common mode noise problem
2 had mid-sensor opens (burns)
Otherwise IV match well
RH% at QTC 30-35%
50 from Pisa
10 have higher currents in IV probing
5 sensors have increased current large enough (>10mA) to cause a chip to have a large common mode noise
Consistent with rate seen in previous production
10 have much lower (>2 times less) currents
Pisa RH% during probing range from 10-50%
Most of these sensors probed at >40% RH

2. Summary of Production 25 Modules Produced
First sensor IV probed
Sensors sorted into three groups
Matching QTC measurements
Higher IV than QTC measurements
Lower IV than QTC measurements
Modules are assembled with sensors with matching or higher QTC measurements
First sensor bias bonded and IV measured
Second sensor bias bonded and IV measured
Module fully bonded, IV measured and module tested
20 modules produced with sensors with matching probe data
One (1038) had 7mA extra current(micro-discharge) and CMN on one chip after module bonding
Additional tests show both no extra current and no CMN, AND extra current and CMN
All other modules had no CMN problem and only small changes in current (<0.5mA)
5 modules produced with sensors with higher IV
4 show micro-discharge large enough to cause a CMN on a chip as expected
2 show burnt mid-sensor opens

3. Slide layout First (near) Sensor IV Second (far) Sensor IV Module IV
Following slides have following layout:
First (near) Sensor IV
Second (far) Sensor IV
Module IV
Results/Comments

4. Modules produced with higher IV measured at UCSB

5.
Mid-sensor open burn seen in sensor , channel 285.
CMN problem seen in chip 1 channel 38 due to sensor CMN Noise problem begins at 90 V

6. Pictures of
Picture of mid-sensor open burn seen in sensor , channel 285.
Picture of channel 38, sensor CMN noise problem begins at 90 V

7. Noise of
Noise start increasing on channel 38 with 10 V bias
Assume micro-discharge
Noise on channel 38 at 100 V large enough to cause 5 ADC common mode noise on chip 1.
Noise reaches maximum at 100 V

8.
Mid-sensor open burn seen in sensor , channel This may explain the increased current seen in UCSB IV probe and the decrease after module bonding.
Channel has about half the average LED response.

9. Sensor mid-sensor open due to burn on
Picture of
Sensor mid-sensor open due to burn on
channel 446, sensor

10.
Sensor scratched due probing of hybrid. Bias and guard rings damage. Now current lower (??). On initial powering, bias current high. CMN problem seen in chip 3, channel 308 due in sensor As run, noise decreases and CMN problem stops.

11. Pictures of
Picture of channel 308, sensor which cause CMN problem on chip 3.
Scratch put into sensor while probing hybrid problem

12.
CMN problem seen in chip 3, channel 336 due to sensor Noise maximum at 240 V, and decreases below level to cause CMN problem.

13. Noise of
Channel 336 shows increasing noise with voltage
Common mode noise on chip 3 reaches maximum at 250 V.
Common mode noise decreases as voltage increase beyond 250 V.
At 400 V, common mode noise gone. Noise on channel 336 at 12 ADC.

14.
Micro-discharge problem seen in chip 1, channel 7-10 in sensor CMN on chip 1 starts at 450V. Increased noise seen earlier on channels 7-10

15. Noise of 30200020001042 Channels 7-10 show increased noise at 400 V.
At 450V, chip 1 begins to show common mode noise

16. Modules produced with similar IV measured at UCSB

17.
Initial test after bonding showed increased current and CMN problem (Channel , chip 2). Problem occurs at ~250 V.
Multiple tests afterwards show currents predicted by probing and no CMN problem OR high currents and CMN problem. NOT UNDERSTOOD

18. Noise from
Channel show increased noise in runs with high bias current.
At 300 V, common mode noise seen in chip 2.

19.
Grade A module. Short in sensor due to scratch not found in sensor probing

20.
Grade B module. Mid sensor open due to burn not seen in sensor probing on sensor , channel 247

21. Sensor mid-sensor open due to burn on
Picture of
Sensor mid-sensor open due to burn on
channel 247, sensor

22.
Grade A module. All faults found expected from sensor database.

23.
Grade A module. All faults found expected from sensor database.

24.
Grade A module. All faults found expected from sensor database.

25.
Grade A module. All faults found expected from sensor database.

26.
Grade A module. All faults found expected from sensor database.

27.
Grade A module. 1 channel with slightly high noise (226, 2.75 ADC) not seen in sensor database

28.
Grade A module. All faults found expected from sensor database.

29.
Grade A module. 1 channel with slightly high noise (11, 3.8 ADC) not seen in sensor database

30.
Grade A module. All faults found expected from sensor database.

31.
Grade A module. All faults found expected from sensor database.

32.
Grade A module. 1 channel with slightly high noise (191) not seen in sensor database

33.
Grade A module. All faults found expected from sensor database.

34.
Grade A module. All faults found expected from sensor database.

35.
Grade A module. All faults found expected from sensor database.

36.
Grade A module. All faults found expected from sensor database.

37.
Grade A module. All faults found expected from sensor database.

38.
Grade A module. All faults found expected from sensor database.

39. Conclusions
Significant differences from QTC sensor probing have been found
~10% of sensors have current increases >20 mA from QTC prior to module assembly
This is consistent with the rate of the chip CMN problem (micro-discharge) seen in productions
Many sensors have much lower IV now
Assume that RH% at sensor QTC cause of problem
After 20 module tested, only one module showed any change in current seen in ProbingAssemblyBondingARC testingBurn-in when using sensors when sensor IV matched at UCSB
Module showed regular current in some tests afterwards
Pre-screening sensors would decrease significantly the number of bad modules made due to sensor issues.
Testing time much reduced because much less repair/debug needed.