Thermal Testing of TOB/TEC Hybrids at UCSB
The CMS detector will run at 20 C in order to lessen radiation damage to the siliconWhy Thermal Test?
Why Thermal Test Hybrids?Some Hybrids fail at 20 CAPVs do not outputHybrid fails to initializeNoise increases in cold (peltier current?) APV: Analog Pipeline Voltage Mode Chip
The 4 Hybrid Cold BoxCold box design and photo courtesy of:Bruno Wittmer and Giacomo Squazzoni @ CERNHow to thermally test hybrids?4 at a time.
The Set-up at CERNPicture courtesy of CERN
The Set-up at CERN
A question at Tracker week
Conclusion
Hey folks, is there someone willing to test hybrids on a large scale?!?!
G.Sguazzoni
Building our own Construction
&
Repair
Slow ControlFirst order of business: hooking things up 5 temperature sensors 1 humidity sensor
1 Water Flow Sensor 1 Air Flow Sensor
Interfacing to a PC: ACDC
Cooling DownCooling Mechanism: Peltier UnitSupercool Peltier:Voltage = 28 V Current = 13 A Power = 350 W
Cooling DownHow long should/does it take to get to 20?Cold chamberPeltier + PlateChillerAir Air Flow(0.05 L/min)Water Flow (14 L/min)
Simplifying thingsS= surface area of enclosure (m )k=thermal conductivity of walls (W/m C)h=convection factor (W/m C) x=thickness of walls (m)
Simplifying thingsAssumptions:
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)m= 2.0 kgc= 910 J/kg C
Simplifying thingsAssumptions2) The convection factor can be calculated by waiting until the system comes to equilibrium
Temp at equilibrium
Simplifying thingsWaiting (I was too impatient to wait for t )h= 7.55 (W/m C)
Calculating time to -20First order linear differential equation:Solution: (T(t=0)=295K)
Not quiteCalculation 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
-20 Reached: On to Testing Set-up in Clean RoomChillerCold BoxPC for Monitoring+ ControllingElectronicsGas/Water Flow Control
Testing Software: ARCSAPV Readout Control SoftwareCommunicatesWith ACDC via TCP/UDP
G.Sguazzoni
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
What are we testing for?Open Channels:Inject charge throughCapacitive coupling of pitch adapter to antenna carrying TTL PulseAntennaPitch Adapter
Easier said than doneSlide courtesy of G.Squazzoni
ARC
NIMpulser
trigger
NIMtoTTL
start
out
50W
antenna very close (~1mm) to the bond pads
Peak - InvOFF
Pulser ONPeak ModeOptimal latency
OPENS
G.Sguazzoni
We thought it was the pulserARC BoardLVDSNIM LogicNIMTTL
LVDS Signal?ARC Boards with functioning External BusSer 29Ser 31
ARC Boards with non-functioning External BusSer 56Ser 57Ser 59
LVDS SignalNoise
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 ICs on lower left of photo. U32
With Pulser OperationalOpens detectable in Scope Mode Intentionally Plucked Bonds Show up in Pedestal Profile
With Pulser Operational.Opens are also detectable in Pedestal & Noise Test Plucked Bonds
Grounding IssuesSame Problem CERN was having.Huge spikes in noise at APV edges
GroundingFerrite Ring around Coax G10/copper strips connect peltier plate to front end ground
Much BetterOld GroundingNew Grounding
Thermal Cycle TestOne Button test
Three Sets of Tests:Pedestal & NoisePulserShort Detection
Automated Test ResultsFinal Report After Thermal Cycle Test:Lists -Shorts -Opens -Noisy Channels
The testing goes onSo far, about 100 hybrids have been thermal cycled.
At maximum capacity: ~28 per day
And the cycling will continue
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