cms tracker week, cern, 24-28 oct 2005 26 oct 2005cms tracker week - module productionsalvatore...

CMS Tracker Week, CERN, 24-28 Oct 2005

26 Oct 2005CMS Tracker Week - Module ProductionSalvatore Costa - Catania

Report from

Module BondingWorking Group

Salvatore CostaUniversità di Catania and INFN – Sezione di Catania

26 Oct 2005CMS Tracker Week - Module Production 2 Salvatore Costa - Catania

Outline

1. Pull Test results

2. Open issues

3. Some peculiar failures



Global review of Module bonding quality

that is,

Module Pull Test results


# Modules Pull Tested


Mean pull forces


StDev/Mean of pull forces



Open issues



TEC Backplane HV Connection

A Bonding and Gantry joined operation

1. Review of established practices in EU and US

2. Preparation for it in Italy


TEC Backplane HV Connection

• New DB Interface with new section

– v. 6.0– v. 6.0_US


HV Connection typesConnection type inventory:1. Conductive Glue dots between gold pad and Sensor (at Gantry)2. Conductive Glue reinforcement over gold pad and Sensor (normally at

Gantry, occasionally at Bonding)3. Bonds without encapsulation (at Bonding)4. Bonds with encapsulation (at Bonding)

Current established practice:• EU: 1 + 2 + 3• US: 1 + 4 [existing TOB modules retrofitted]

Reason for reinforcement (EU) or encapsulation (US): Bonds on back are considered at higher risk of being damaged when

modules mounted on rods or petals because people’s attention is focused on front and the back may get neglected.

Susanne KyreTracker week, October 2005

Material and Preparation• Sylgard 186 Silicone

Elastomer, 2 part kit, 10:1 mixing ratio (manufacturer: Dow-Corning)

• Mixing cups

• Mixing sticks

• Digital bench scale

• Small vacuum chamber or centrifuge for degassing


Dispensing Equipment• Pneumatic glue dispenser

with foot pedal and timed pulse option (manufacturer: EFD model: Ultra 1400) www.efd-inc.com

• 3ccm syringe barrel and piston (EFD)

• Smooth-flow tapered tips, gage 20 (EFD)


Set up Equipment• Base plate (UCSB design), to

hold the module on a module carrier upside down

• Plastic trowel (UCSB design), to spread the encapsulant over the wirebonds and to keep the height of the encapsulant below the maximum height

• Stereo microscope (optional)


Procedure I• Mix encapsulant, degas the

mixture and fill syringe

• Set pneumatic dispenser to 15 psi and 1 second dispense time

• Set module in carrier upside down onto base plate

• Dispense a line of encapsulant across the width of the wirebonds


Procedure II• Position the trowel with one

leg on the sensor, one leg on the kapton

• Spread the encapsulant over all 15 wirebonds by sliding the trowel across the bonds

• Once the trowel is past the wirebonds, lift it up and clean it off with a dry tissue paper


Procedure III• Check that all wirebonds are

covered completely with the encapsulant (this can be done with or without a stereo microscope)

• If necessary apply more silicone and repeat the troweling procedure

• Cure for 24 hours with the backside of the module facing up to avoid beading up of the encapsulant


Established EU procedure

M.Krammer:

no bond encapsulation experience in

EU TEC community: use conductive glue reinforcement

All tests OK

This procedure is now officially requested by TEC to Italy


…Except for R4S modules…

…because:


How is Back bonding going?

• Aachen: Vibration test of backplane HV bonds: with additional glue near bonds, but bonds bare, in one module some bonds broke, in another module no bonds broke. In modules with encapsulated bonds, none broke.

• Strasbourg: Bonded (in hole) 16 modules electrically OK• Vienna: Bonded (in hole) 80 modules previously front-

bonded, using special supports that hold module carrier all around: sensors not supportedNo problems.

• Hamburg: Not started yet since the backplane jigs are not done before next week. For the last weeks have reinforced the glue connection on the backplane with conductive glue, for some modules where this had not been done before at the Gantries.


Recipe for TEC Mod prod in Italy

At the end of the Bonding Meeting, I conveyed its outcome at the Gantry Meeting…

– Bari has agreed to use conductive glue under HV pad when assembling modules

– Bari has agreed to place conductive glue reinforcement over the “top” of the T-shaped pad

– Bonding centers will bond “in the hole” without encapsulation



Some peculiar

Module failures


Some recent peculiar Module failures

• IV failures:– Affect modules not randomly in time, but in concentrated clusters: Recently: 5/53 in Aachen, 4/36 in Catania Had also been seen at least in Catania and Padova in the past.

• Seen (in Catania) first TIB module where gold layer on HV pad on back is peeling away. – May drag away the bonds with it– Module will be declared faulty Repair center

• Since Sep we see many TIB PA’s where bonds would stick with unusually high parameters, or would not stick at all, in one or more of these locations: – Pads 1-2, 27-30, 738-741, 767-768 – Seen in: Bari, Catania, Padova. – Suspect bad PA metallization in those (symmetric!) spots

cms tracker week, cern, 24-28 oct 2005 26 oct 2005cms tracker week - module productionsalvatore...

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