Glue Programme

(Tim)

Glue Programme 2

Origins• Came out of ‘decision’ to migrate from SE4445 to

‘something else’ for module mounting during stave production.

• General realisation that glue choices across project are not ‘well defined’.– Likes and dislikes– Reasons for choice lost in history

• What’s Been Done ?– Attempt to elicit information by polling whole community

10/07/2013

Glue Programme 3

RequestI'm trying to compile a survey of the different adhesives which are being considered for use at various stages of strip stave and petal assembly. The following list is a compilation of different gluing steps from hybrid assembly all the way through to stave core assembly.

1) ASIC to Hybrid 2) Hybrid to Silicon 3) Silicon to bus tape 4) Silicon to HV bias pad (if different from #1). 5) Honeycomb to Carbon-fibre face sheet 6) Cooling tube to thermally conducting foam and foam to face-sheet

I'd be grateful if you could e-mail me any information on any gluing experience (both good and bad!) for any of the above steps. Also, I'd be especially interested to learn if the subject of adhesives is either one which interests you or in which you have expertise!

Many thanks, Tim

10/07/2013

Glue Programme 4

Responses• Ingrid

– I think that would be very interesting to join forces. I actually asked Luise to do a survey of what studies have been done earlier on when the current detectors were prepared. Especially to understand what kind of radiation hardness and aging tests were done. For me it was not really clear if it is reasonable to do standard aging tests were a humidity step is included (one cycle with higher humidity, percentage not really defined). Did you do something like this before ?

• Nigel– I am interested. For petals, we glue silicon to face sheet (or more correctly, silicon to parylene-C coating on face

sheet). And we glue bus tape to face sheet. You could also add adhesives used inside the bus tape. – Our experience so far:

• Dow Corning 4445 for silicon to facesheet: • Spec has break-down field on the edge for endcap use. • We have bought some and will try it. It is very expensive in the Netherlands.

• Richard F– I spent from 1997 to 2003 studying polymer behavior including some glues so my expertise is more the glue structure

and how to measure this such as contact angle measurements, surface measurements such as wetting effect etc etc. – Bottom line is this was something I could do, have the test kit in house to access and am interested in. However I'm not

sure how much to bite off here but would like to help.

• Dave Lynn– BNL/Yale uses for (5) Hysol with 30% BN. There appears to work well although we have yet to do detailed testing. For

(6) cooling tube to foam we seal the foam with hysol+30 % BN and then use CGL. We plan to move to an Hysol + 30% BN only solution as the UK has had good results with this (but I have not yet seen any thermal contraction measurements). But so far we seem to have good results with the CGL (based upon camera thermal imaging) but cannot yet quantify. For (6) foam to facing, we again use Hysol +30% BN with good results (again only based upon thermal imaging).

10/07/2013

Glue Programme 5

… and more…• Steve McM

– During our discussion on Friday I said that I would pass on the headline topics that came up in the discussion with Martin on the Thursday Pixel in Manchester. Items to be added to the list of things to look at in the glue group.

– In no particular order they were• 1. Thermal conductivity• 2. Loading the glues to improve TC (Boron nitride etc)• 3. Glass transition temperature• 4. Radiation tolerance• 5. Pot-life• 6. minimum order quantity• 7. Time to delivery• 8. Cost• 9. Preparation details• 10. Disposal at end of use• 11. MSDS (datasheet safety)• 12. Viscosity• 13. Rework issues• 14. Expansion or contraction of the glue on curing• 15. Is the glue hygroscopic• 16. Cure temperature• 17. The temperature (value and stability) of the cure environment• 18. Hardness• 19…….

10/07/2013

Glue Programme 6

… and the big one!• Eric Anderssen

– I've seen this request before, and wish the best, but what are you trying to get at?

– An old trope in the adhesives business is that all adhesives are the same - it's all about how they get into the joint; their properties during application/assembly are as, or more, important than their cured properties, because they all perform similarly after cure. • When I say 'old trope' I mean old--I heard this at industry conferences back in '89, and it was common knowledge

before I started attending--admittedly from companies in the business of dispensing said adhesives, but they had (have) a point.

– An adhesive joint isn't reliably predictable if you can't control how much adhesive gets there, how thick it is, or how well filleted the joints are. • The properties of mixed 2-part systems or defrosted 1-part systems (pre-cure/dispensing) trump 'ideal' cured

properties because control of application properties yields controlled cured properties.• The 10-50% variation in 'measured cured properties' reported by various institutes are likely completely obscured

by their assembly processes. That is a problem. If a syringe applied (low viscosity) thermal adhesive performs better than a screed-mask applied (thixotropic) adhesive, post-cure, is it because one adhesive is better than the other, or is it because the folk that report have better control over their process?

– In my experience, assembly process dominates adhesive selection. Not to confuse the issue, but at LBNL we either select, or modify, adhesives specifically for their characteristics during assembly. • For example, if we want or need to use 9396, but need it to be more viscous to stay where it belongs in a joint,

either we wait during it's pot-life until it becomes more viscous (partially cured), but if the process needs more time, we add Cab-o-sil (microspheres and talc) to change it's viscosity in-pot-life allowing time to introduce the adhesive to the joint. In terms of performance, there is a lot of overlap.

– How do you plan to normalize the data you request across the numerous and variable processes (and internal modification of adhesives)?10/07/2013

Glue Programme 7

Gluing Step Adherends Required Properties

Cure Conditions Candidates

ASIC to Hybrid Silicon to Au/Cu

Thermal conductivityElectrical conductivity

T ≈ 20°CP ≈ 0barg

t ≤ 24h

Hybrid to Silicon

Silicon / Kapton

Compatibility with silicon

T ≈ 20°CP ≈ 0bargt ≤ 24 hr

Silicon to Bus-tape

Silicon / Kapton

Thermal conductivityCompliance

T ≈ 20°CP ≈ 0bargt ≤ 24 hr

SE4445

Silicon to HV bias pad Silicon / Gold Electrical

conductivity

T ≈ 20°CP ≈ 0bargt ≤ 24 hr

CFRP face-sheet to core

CFRP / (Nomex / CFRP)

Mechanical integrity

T ≥ 20°CP ≤ 0bargt ≤ 24 hr

Hysol 9396Hysol 9309.3NA

CFRP face-sheet to Th. Cond foam

CFRP / Carbon Thermal conductivity

T ≥ 20 °CP ≤ 0bargt ≤ 24 hr

Hysol 9396 + boron nitride

10/07/2013

Glue Programme 8

Conclusions …. So far• In general a poor response

– atlas-upgrade-itk-strip-modules (108)– atlas-upgrade-itk-engineering (???)– 6 replies…

• General ‘interest’ in the problem but no ‘real’ work to establish reasons for pre-existing choices – If anything, the work done in ‘old’ WP4 materials on adhesives is

almost all there is!

• Next Steps…– Think a little about Eric’s response – i.e. how is just as / more

important than what– Define a programme to establish a baseline for missing areas

10/07/2013