Flex attachment to the stave Glue selection: preliminary tests 30/08/2011 Maxence CURDY François-Xavier Nuiry CERN PH/DT/PO

Flex to stave assembly Genova flex Goal: Realise a reliable and accurate fixation between the flex and the omega carbon skin Accuracy / omega: Better than +/-0.3mm About +/-0.1mm Technology used: Glued joint Stress in the glue: Currently tested (through several shear tests) and also under calculus The total force considered : Flex Glued over ~350mm Max stress Max stress F F 2F=(ES)/L * (thermal contraction)= (11500*0.6*11.5)/350 * 0.55 = 125N F~62.5N, If the flex young modulus is 11.5GPa

65 test samples manufactured Flex to stave assembly Genova & Bonn flex Glue Comments Araldite 2011 Used everywhere in ATLAS Currently tested Scotchweld 2216 Soft, easy to apply, thin layers (~10 microns) DP460 easy to apply, no data about radiations DP490 Quite good adherence on the Kapton, no data about radiations Test stopped Eccobond 286 Hard to apply, thicker layers, bad adherence Staycast 2850 + cat 9 hard comportment thicker layers (50 microns) CAF 4 [Silicone] Bad adherence on the Kapton 65 test samples manufactured Cleaning at surface treatment workshop Surface activation with Plasma Shear tests Glue selection

Plasma set up Polymer lab at CERN Displacement in X with the handle

Preliminary information on Kapton surface activation Speed and Distance between the BLASTER nozzle to substrate surface (Kapton) have to be determined in order to stay under 120⁰C. ( given by Rui) But tests show that we need to heat a bit to activate the surface. So we must find a compromise between speed, height and number of run.

Plasma Tests Performed on Kapton Cleaning with ACETONE -->ETHANOL Kapton sheet   test to be realized hauteur tete mm vitesse Ecoulement Forme goutte T⁰C Observations supplementaires 1 Kapton seul Nettoyer a acetone , & Deposer eau distillée sur kapton. Observer l'ecoulement de l'eau _ Lent Ronde Tension superficielle (Encres Test): ≤ 42mN/m 2 Nettoyer a acetone , appliquer plasma puis appliquer eau distillée pour verifier mouillabilité 20 2 cm/s ?? 1 Passage → Pas d'activation 3 0.4 cm/s 4 15 Ovale 1 Passage 5 10 Ovale -Plate 6 12 4 cm/s <132⁰C 7 >132⁰C 2 Passages 8 Kapton avec protection 9 <120⁰C 8 cm/s 11 13 2 Passages → Protection fond 14 Plate 2 Passages → Protection fond 16 17 4 Passages 18 4 Passages [10s] 19 <116⁰C 4 Passages [5s] 4 Passages Tension superficielle (Encres Test): > 70mN/m 21 6 Passages Tension superficielle (Encres Test): > 70mN/m

Wettability control on Kapton sample LF 7001 (13μm) The effect of plasma treatment can be controlled by a wetting test. But this is just a visual check, it’s not precise. Not activated surface Activated surface When the nozzle is adjusted at 8 mm and no displacement  T⁰C max about 160⁰C

Treatment control The treatment can also be controlled with test ink. When the surface tension is high  the surface became wettable and it’s easier to glue it. 42mN/m We control the surface tension to 70mN/m. The control of the surface tension shows that from 4 run, the number of run doesn’t influence activation. Kapton 70mN/m Kapton after 4 run, 8mm and 8cm/s 70mN/m Kapton after 6 run, 8mm and 8cm/s

Procedure for glued samples Glue preparation Series of 5 Kapton specimens are activated (4 runs) directly between two foils of 0.6mm (no time lost for gluing). Put glue on the Kapton (4*4mm) and calibrate glue with foils (10μm of glue). Position carbon fibre specimens on a levelling pad. Glue the Kapton on carbon fibre specimens. 2 3 Glue Activation 4 5 Kapton + Carbon Fibre specimen

Glued samples Thermal cycling 100 cycles Temp ˚C +50 -40 Time, min 50 minutes