Conductive glue tests. J.Wickens 12/7/04 Used small pieces of HV kapton cut from redundant (old) stock, glued to silicon test structures from Karlsruhe. Kapton was cleaned with alcohol. Silicon cleaned only if clear contamination on surface (rare). Glue mixed in 3 g lots (balance recording to 0.01 g) and applied via syringe. First set of test samples. 32 samples for each of 3 mixes glue/hardener : 50-50, 40-60, Within each mix, 4 samples for all combinations of : - 2 glue spots or 1 glue spot - 0 min open time ( apply glue and make joint) 30 min open time ( apply glue and wait 30 minutes before making joint) - two methods of gluing : ‘Direct’ (D) ‘Gantry’ (G) Weight Weight Ka Ka Si Si Carbon fiber ‘Gantry’ is attempt to simulate fact that the kapton can ‘float’ in the gap foreseen on the assembly plates. Samples pulled using hook attached to existing hole in gold T section of kapton. Ka Si

A) Tests before temperature cycling bonds (2 of each type for each glue mix) tested with a pull limited to 420 g. Mix Curing time 24 hr Fraction reaching 420 g 11/16 ( minimum break 100 g ) hr 2/16 ( 4 break with scale pan only <20 g ) hr 16/ > Maximum glue strength is not reached after 24 hour curing (see also results after temperature cycling ). Comparing mixes tested after 24 hours ( 8 bonds for each mean pull ) : Mix Mix Mean pull (g) Fract.>420 g Mean pull (g) Fract.>420 g 0 min open time >333 5/ /8 30 min open time >393 6/8 >182 2/8 2 glue spots >420 8/8 >241 2/8 1 glue spot >306 3/ /8 ‘Direct’ gluing >407 7/8 >276 2/8 ‘Gantry’ gluing >320 4/8 80 0/8 For the mix tested after 45 hr curing time, one bond of each type was pulled to a maximum of 1500 g. Open 0 : 2 spot : D >1500 g Open 0 : 1 spot : D 880 g Open 0 : 2 spot : G 840 g Open 0 : 1 spot : G 430 g Open 30 : 2 spot : D >1500 g Open 30 : 1 spot : D 800 g Open 30 : 2 spot : G 1200 g Open 30 : 1 spot : G 520 g > mix (g-h) is clearly a problem (see also after temp cycling) > no evidence of any problem with 30 minutes open time ( pot life claimed to be 3 hours) > ‘gantry’ gluing procedure is less robust ( probably glue is spread over a smaller area )

B) Tests after temperature cycling untouched bonds + 23 bonds surviving preliminary tests were put through 6 temperature cycles > 50 deg C. Pulled to destruction. One of the 23 previously pulled bonds failed to reach original pull strength. Mix Mix Mix Open Spots D/G # # # max pull g single pull pre T cycling 0 2 D > G D > G D G D G <80 2 * * both bonds break with just the scale pan (larger pan than before T cycling) + one sample lost when silicon broke Similar conclusions : (g-h) mix is unreliable. - no evidence that 30 minutes wait between dispensing glue and making joint poses a problem ( should be adequate for gantry operations ). - ‘gantry’ bonds weaker than ‘direct’ (g-h) mix is similar to can only compare mix results before/after T cycling. No clear evidence of any problem, but was investigated further (next slide).

Second set of test samples. To check further any effect of temperature cycling, 40 new test samples were prepared. All were mix, 0 open time, 1 spot. Half glued ‘direct’, half glued ‘gantry’. 20 samples (10 D, 10 G) were temperature cycled > 50 deg C six times. All pulled at the same time ( 3 days after gluing ). 4 bonds (all of ‘gantry’ type ) failed with just the weight of the scale pan - plotted as < 50 g below. Direct uncycled Gantry uncycled <50 g = 50 g excluding <50 g Direct cycled x6 Gantry cycled x6 <50 g = 50 g excluding <50 g No evidence of extra problems due to temperature cycles. - No explanation why in this set of samples the ‘direct’ gluing is less strong than in previous set. - No obvious reason (from inspection of kapton and silicon after break) why some bonds are very weak. This only occurred for mix and ‘gantry’ gluing in the previous set.