1/8/04lance simms thermal testing of tob/tec hybrids at ucsb

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

1/8/04 Lance Simms

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

1/8/04 Lance Simms

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

1/8/04 Lance Simms

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…