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