Module Production

T. Bowcock

News Since Last Meeting

• Engineering Design Review (20-21st April)– Mechanics including module and fixtures– Components– Assembly Procedures– Quality Assurance– Burnin and Testing– Process Control– Towards production readiness

At time of EDR

• April 2005– Received a pre-production batch of hybrids

(K-04) laminated onto substrates• Actually an additional run added for safety• Stevenage had already produced hybrids to spec.

– Metrology• Twist in the hybrid• Maintain close tolerances for the r.f. foil

Other known problems

• Pitch adaptors– Very low yield ~ 10% which would bring the

assembly to its knees

EDR

• Issues with the twisted hybrids– Avenues to solve problem

• Find problem with last production and fix it• Cold lamination• Mechanical Constraint (if both others failed)

• Pitch adaptor yield

• * Cable Stress on Module

Twist post EDR

• Major part of programme to discover why the “twist” happened– Log books at Stevenage and Liverpool– Visit to examine handling

Twisted Substrates

• First difference was– The use of larger CF frame for ease of handling

• This introduced extra warp so was removed• No such thing as a “minor” change. (“no problem!”)

• Processing repeated– Flatter but still not flat

• Stress relief– Single heating at 180 improved matters– Thermal cycling (ATLAS cycle ~-30 to ~+30 10 times

over 3 days) to check stability– Additional problem with partial frame found (now

fixed) that led to delamination

Flat Substrates

• Only other differences were– New TPG from Advanced Ceramics– New CF from original source

• Note this is heavily QC and is aerospace grade.

• TPG samples appeared identical• CF had a subtle difference

– The original CF was pre-preg and was at the tail end of its lifetime (1 year)

– New CF was “new” i.e. at the beginning of its shelf life

Flat Substrates (May 2005)

• Process retuned for new material– Extended platen heating (1 hour to 2 hours)

• Much improved– Twist now at ~100 micron level

• Artificial ageing of CF– Partial polymerization?– Perfect “floating” substrates (3)– Best surface finish observed

Current Status Substrates

• Cold Lamination– Total in-house production including gluing

circuits has produced perfectly flat hybrids• Air not adequately removed from under circuit• Fall back would require a little more R&D

• Normal production– Flatness of substrates solved(?)– New kits including frames sent to Stevenage– Lamination today

Pitch Adaptors

• Over last month over 100 PA tested• Yield now ~ 90%

– Needs to be > 80% for production purposes

• 5-6 PA’s per day tested with a team of 6 trained physicists and engineers on a shift basis

• Order being placed with CERN for main production– 40kCHF!

• We have enough for 10 prototype modules

Cable Stress

• Stiff kapton cables can exert substantial forces (and torques) on the module

• Movement critical to tolerances

• Issues of “creep”/long term tests

Cable Loading

• The VELO module design as reviwed at the EDR is distorts under cable pressure. The tip of the module, closest to the rf foil, will move by approximately 60 microns if a pushing force of about 1N is applied to each of the two cables one side of the module. If the cables are “pulled” away from the r.f. foil there is evidence for the paddle buckling under these force. This is not a recommended mode of operation.

T1 T2

T3 T4

T5 T6

+ve z DISTORTIONS

+y

+x

Cable Stress

• Movements measured

• To date (one month) no evidence of creep

• Design for stress relief– Clamp to base

• Working in limited volume• Fixed cable lengths with tolerances

– Cable removal tool under design

Also since EDR

• Mechanics for sensor gluing assembly complete (complex)

• Major Laser Rig mechanics complete• Design for handling and storage jig

– Al Prototype made– Plastic lightweight version ordered

• Double sided bonding jig improved– 3 new vacuum systems installed to improve suction

on all equipment (high volume scroll pumps) external to clean room

• Stevenage agreed to glue PA’s

Other issues

• K&S 8090 repair status– Final negotiation with K&S for coverage during period

of production. • (2) H&K710 now switched to LHCb production

(backend bonding)• Additional TPG ordered (no delay)• Consultant at Micron

– Good reports– Vacuum tests underway– Request for more 8 jigs (from Liverpool) to meet

production needs. This could be a problem…emergency meeting called

Biggest remaining Issue

• IF twist is solved-hybrid at level we wish– Final paddle hybrid jig can be built – final design

• If hybrid is twisted 100-200 microns then paddle production has to be modified slightly to allow for a face to be ground

• If hybrid is more twisted and fails stability tests then we have to use our addon constraint– Works(!) but requires different assembly jig

• In any scenario we are about 1 month away from being able to build this in.

Current Schedule

• If all goes well with todays production then we predict– 5 prototype K-05 modules should be built by

end of July– Start of production by 3 week August

• Additional delay of the twist ~ 2 months

News on Staff

• Torkjell Huse (Oslo) has joined Liverpool– Extensive experience from ATLAS modules

Production Readiness• Pitch adaptor yield to be raised to above 80%• “Curvature” of the hybrids to be reduced to <200 microns ()• Pitch adaptor attachment to gluing to be proven by Stevenage Circuits or their sub-

contractor • Completion and programming of the Assembly robot to allow rapid alignment of

the sensors to the hybrids• Completion and programming of the Glue robot to allow rapid dispensing of

structural adhesive• Completion of ageing tests on the glue joint between paddle and hybrid • Programming of backend bonding programmes on HK710 for K-05 • Programming of frontend bonding progammes on KS-8090 for K-05• Design of the assembly jig for hybrid-paddle assembly• Commissioning or extension of 2 DAQ systems (hybrid, laser, burnin).• Completion of db for production QC and process control • Commissioning of laser system• Design and commission of burnin system

Process Being Finalized

Hybrid Assembly

http://hep.ph.liv.ac.uk/~gdp/lhcb

Produce list of db entries, how there are used etc.

Welcome comments!

Summary

• Lots of work to do before PRR

• R&D phase “complete” and gearing up for poduction

• By the end of week should have final confirmation of twist problem

• Risks– Delivery of sensors– K&S 8090