Thermal Testing of TOBTEC Hybrids at UCSB

1
Thermal Testing of TOB/TEC Hybrids at UCSB
2
Why Thermal Test?
The CMS detector will run at 20 C in order to
lessen radiation damage to the silicon
3
Why Thermal Test Hybrids?

• Some Hybrids fail at 20 C
• APVs do not output
• Hybrid fails to initialize
• Noise increases in cold (peltier current?)

APV Analog Pipeline Voltage Mode Chip
4
Set-up in Clean Room
5
Cooling Down
How long should/does it take to get to 20?
Air
Water Flow (14 L/min)
Cold chamber
Chiller
Peltier Plate
Air Flow (0.05 L/min)
6
Simplifying things
S surface area of enclosure (m ) kthermal
conductivity of walls (W/m C) hconvection factor
(W/m C) xthickness of walls (m)
7
Calculating time to -20
First order linear differential equation
Solution (T(t0)295K)
8
Not quite

• Calculation says that plate
• should reach 20 in 14
• minutes.
• Actual time 21 minutes
• Possible problems
• Unaccounted heat influx through leaks or
  grounding
• strips connecting plate to outside
• Assumptions made are flawed
• Missing term in differential equation

9
Interfacing to a PC ACDC
10
Testing Software ARCSAPV Readout Control
Software
Communicates With ACDC via TCP/UDP
11
What are we testing for?
Shorted channels On each clock, charge injected
into every 8th channel. Shorted channels share,
ADC amplitude is diminished.
128 Channels per APV -6 APV hybrids 768 -4 APV
hybrids 512
12
What are we testing for?
Open Channels Inject charge through Capacitive
coupling of pitch adapter to antenna carrying TTL
Pulse
Antenna
Pitch Adapter
13
With Pulser Operational.

• Opens are also detectable in Pedestal Noise Test

Plucked Bonds
14
Thermal Cycle Test

• One Button test
• Three Sets of Tests
• Pedestal Noise
• Pulser
• Short Detection

15
Automated Test Results

• Final Report After Thermal Cycle Test
• Lists -Shorts
• -Opens
• -Noisy Channels

16
Testing Replicating
UCSB Cold Box ready for full scale testing 28
hybrids per day Fermilab Cold Box near
completion Mexico City Cold Box next on the
list