Report from Bonding Working Group Meeting by Salvatore Costa, Università di Catania and INFN – Sezione di Catania

1. Report fromModule BondingWorking Group Meeting Salvatore Costa Università di Catania and INFN – Sezione di Catania

2. Outline • Global info on production bonding of the Modules • Global review of Module bonding quality indicators • Short summaries on specific topics discussed at the WG Meeting

3. Globalinfo on production bondingreview of Module bonding quality

4. Production Summary after Hyb prod resumed with stiffener added to kapton cable

5. Production Rate • It continues to be globally true that Bonding is not a bottleneck in the production flow. • In all centers modules are bonded within single-digit number of days from reception

6. Module Pull Tests Performed Results in DB from 13 Centers out of 14 (up from 9 three Mtgs ago) # Modules pull tested after 01Dec2003 (since last Mtg)

7. Pull test results 5g BA CT FI PD PI TO FL FL SB SB HA KA ST ST VI ZH . ss ss ss

8. Bonding problems We had no reports of pathological problems. Non-severe problems: • Catania changed to a new toot type for last module bonded; with parameters that result into reliable bonding, but still not optimized, had much higher pull forces (13-15 g) but all lift-off’s vs. heel breaks. • Firenze complained that the filter capacitor gold pad was particularly dirty in a few recent modules, resulting into failing bonds. • Karlsruhe got their first 38 CMS modules (TEC R3); reported ‘standard’ bonding failures in about 2/3 of the modules, traced to vacuum/support problems • feedback given for jig improvement • Vienna warned that Hybrids in their modules (bonded at Fermilab) have power bonds in groups of 3 vs. 5 present in Hybrids bonded at CERN. • Zurich reported that out of 108 TEC R4 modules they bonded, “a few” had floating sensors and needed special care when bonding.

9. Selected highlights from theBonding WG Meeting of 08 June 2004

10. Pull test data comparison • Direct comparisons between centers must involve correction for loop angles • Launched a campaign to document loop in PA test areas, typically involving these steps • Document the original bond • Straighten bond to (near) triangular shape • Measure the angle at the bond foot • Determine correction factor for pull strength • 5/14 centers have already responded and provided their loop doc at the Meeting. • Will gather missing info and then use it to scale data in PA TA plot.

11. Pull Force correction factor Correction factor: a = 1 / (2 sin) For symmetrical bond:

12. Loop angle  Correction factor Catania Correction factor: 1

13. 525 2nd 1st 1800 Loop angle  Correction factor Padova = arctan(525/900) = 30º Correction factor: 1

14. Module Repair Centers • We were requested to discuss the criteria to decide when to send a Module to the new official Repair Centers, from a Bonder’s point of view. • I will report in detail to TPO. General remarks: • We perceive these centers more as debug places where teams of dedicated people study in deeper detail Modules with non-trivial problems, so that normal production can continue at the usual rate. • Strictly speaking, trivial mechanical Module bonding failures should not be matter for these Centers: a) there is nothing to study; b) bonding centers (operators) are either able to repair them right away or, if they can’t, then most likely the debug centers can’t either. • To repair damage to APV-PA bonds (typically caused by handling accidents), send Module back to the Hyb bonding place. […] • For all other cases, which means a variety of electrical misbehaviors that may or may not be related to bonding problems, report the problem and let the ‘experts’ at the Debug Center decide if they think they want to study that Module [report procedure…]

15. Module grading in Tracker(DB) • ModTest WG has clear criteria to grade Modules according to number of bad channels and other electric properties: grade A, B, C, F • Gantry is in the process of implementing a similar grading scheme based on the achieved alignment of components on the Module • Bonding de facto has already a similar scheme, although we never called it “grading”. • From the Bonding operation, we issue a negative flag in TrackerDB only if the Module is • Declared unbondable or however unusable at Pre-bonding “inspection” • Declared unusable at Post-bonding inspection • Currently we never issue a negative flag based on quantitative variables: • Number of unbonded strips • Number of bonding failures • Pull test results • We do assign, however, different positive flags based on number of unbonded strips (“grading”): 0 <1% unbonded Sensor strips 1 1-3 % unbonded Sensor strips 2 > 3% unbonded Sensor strips • These thresholds were decided quite arbitrarily about 1.5 years ago.

16. Grading from Bonding (preliminary!) • We agreed on: • Keep Flag -1 if module found unusable at pre- or post-bonding inspection • Not use pull test values for grading because it would require pull test on all modules • Adjust our current grading based on # unbonded strips in order to match the ModTest criteria: • 0 : <1% unbonded Sensor strips (matches Grade A) • 1 : 1-2 % unbonded Sensor strips (matches Grade B) • -1 : > 2% unbonded Sensor strips (matches Grade C) [and perhaps -2, -3,… for different reasons] • We debated but concluded we need more time before we can come up with a well-thought scheme: • Including levels of grading based on indicators of the mechanical quality of the bonds, such as • The number of repaired failures This is delicate because to be meaningful it must include a breakdown of the reported repaired failures based on reasons for the initial failure and repair manner. • The number of bias bonds that could actually be made Any changes to the grading scheme can only be implemented with a new DB I/F version. We will have to make a script to automatically change in DB the flags for existing data where appropriate (should be just a few).