1/8/04lance simms thermal testing of tob/tec hybrids at ucsb
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1/8/04 Lance Simms
Thermal Testing of TOB/TEC Hybrids at UCSB
1/8/04 Lance Simms
The CMS detector will run at –20 C in order to lessen radiation damage to the silicon
Why Thermal Test?
1/8/04 Lance Simms
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
1/8/04 Lance Simms
The 4 Hybrid Cold Box
Cold box design and photo courtesy of:Cold box design and photo courtesy of:Bruno Wittmer and Giacomo Squazzoni Bruno Wittmer and Giacomo Squazzoni @ CERN@ CERN
How to thermally test hybrids?How to thermally test hybrids?4 at a time.4 at a time.
1/8/04 Lance Simms
The Set-up at CERN
Picture courtesy of CERN
1/8/04 Lance Simms
The Set-up at CERN
1/8/04 Lance Simms
A question at Tracker weekConclusion
Hey folks, is there someone willing to test hybrids on a
large scale?!?!…
Hey folks, is there someone willing to test hybrids on a
large scale?!?!…
1/8/04 Lance Simms
Building our own
ConstructionConstruction
&&
RepairRepair
1/8/04 Lance Simms
Slow Control
First order of business: hooking things up
• 5 temperature sensors• 1 humidity sensor
• 1 Water Flow Sensor• 1 Air Flow Sensor
1/8/04 Lance Simms
Interfacing to a PC: ACDCInterfacing to a PC: ACDC
1/8/04 Lance Simms
Cooling Down
Cooling Mechanism: Peltier Unit
Supercool Peltier:-Voltage = 28 V- Current = 13 A- Power = 350 W
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Cooling DownHow long should/does it take to get to –20?
Cold chamber
Peltier + PlateChiller
KTB 283
CT
AirKTS 295
Air Flow(0.05 L/min)
Water Flow (14 L/min)
1/8/04 Lance Simms
Simplifying things
)(8.4300 CBC TTK
WWP
hkxTTS
P SCI 1
)(
S= surface area of enclosure (m )k=thermal conductivity of walls (W/m C)h=convection factor (W/m C) x=thickness of walls (m)
2
2
CT BT
ST
1/8/04 Lance Simms
Simplifying things
Assumptions:1) Most of the heat transferred to the system goes into cooling the aluminum peltier plate (specific heat of aluminum is much greater than that of air)
dt
dTmc
dt
dQ m= 2.0 kg
c= 910 J/kg C
1/8/04 Lance Simms
Simplifying thingsAssumptions
2) The convection factor can be calculated by waiting until the system comes to equilibrium
CI PP
hkxTTS SE
1)(
)(8.4300 BE TTK
WW
ET Temp at equilibrium
1/8/04 Lance Simms
Simplifying thingsWaiting… (I was too impatient to wait for t )
CTE21
h= 7.55 (W/m C)2
1/8/04 Lance Simms
Calculating time to -20
CTmchk
xTTS SC
1)(
))(8.4300( CB TTK
WW
First order linear differential equation:
Solution: (T(t=0)=295K)
KKetT tC 9.2515.43)( )0045.0(
1/8/04 Lance Simms
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
1/8/04 Lance Simms
-20 Reached: On to Testing-20 Reached: On to Testing
Set-up in Clean RoomSet-up in Clean Room
ChillerChiller
Cold BoxCold Box
PC for MonitoringPC for Monitoring+ Controlling+ Controlling
ElectronicsElectronics
Gas/Water Flow ControlGas/Water Flow Control
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Testing Software: ARCSTesting Software: ARCSAPV Readout Control SoftwareAPV Readout Control Software
CommunicatesCommunicatesWith ACDC With ACDC via TCP/UDPvia TCP/UDP
1/8/04 Lance Simms
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
1/8/04 Lance Simms
What are we testing for?
Open Channels:Open Channels:Inject charge Inject charge throughthroughCapacitive coupling Capacitive coupling of pitch adapter to of pitch adapter to antenna carrying antenna carrying TTL PulseTTL Pulse
AntennaAntenna
Pitch AdapterPitch Adapter
1/8/04 Lance Simms
AR
C
NIMpulsertr
igge
r NIMto
TTL
start
out
50“antenna” very close (~1mm) to the bond pads
Peak - InvOFF Pulser ON Peak
Mode Optimal
latency
OPENS
Easier said than done
Slide courtesy of G.Squazzoni
1/8/04 Lance Simms
We thought it was the pulser
ARC BoardLVDS
NIM LogicNIMTTL
1/8/04 Lance Simms
LVDS Signal?
• ARC Boards with
functioning External Bus– Ser 29– Ser 31
• ARC Boards with
non-functioning External Bus– Ser 56– Ser 57– Ser 59
LVDS Signal
Noise
1/8/04 Lance Simms
ARC Controller Problem
• Bad Batch of ARC BOARDS: LVDS Driver and LVDS Receiver U32 and U33 were switched during board assembly. Problem was never discovered.
• External Buss connector and associated IC’s on lower left of photo. U32
1/8/04 Lance Simms
With Pulser Operational…
• Opens detectable in “Scope Mode” Intentionally Plucked Bonds Show up in Pedestal Profile
1/8/04 Lance Simms
With Pulser Operational….
• Opens are also detectable in Pedestal & Noise Test
Plucked Bonds
1/8/04 Lance Simms
Grounding Issues
Same Problem CERN was having….
Huge spikes in noise at APV edges
1/8/04 Lance Simms
Grounding•Ferrite Ring around Coax
•G10/copper strips connect peltier plate to front end ground
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Much Better
Old Grounding
New Grounding
1/8/04 Lance Simms
Thermal Cycle Test
“One Button” test
Three Sets of Tests:
• Pedestal & Noise
• Pulser
• Short Detection
1/8/04 Lance Simms
Automated Test ResultsFinal Report After Thermal Cycle Test:Lists -Shorts -Opens -Noisy Channels
1/8/04 Lance Simms
The testing goes on…
So far, about 100 hybrids have been thermal cycled.
At maximum capacity: ~28 per day
And the cycling will continue…