Minutes of meeting
11th September: Chemical
etching on 0.1 mm thick batch and then
bagging in vacuum tight bags; (
Monday, 13th September, morning: Tungsten tiles incoming in Plyform;
Monday, 13th September, afternoon: Primer application and drying in a place that does not produce contamination;
Friday, 18th September: T-peel test;
Monday, 20th September: coupons
The following numbers refer to the TART paragraphs
Deviation: visual inspection must be performed after chemical etching, lying the tiles on tool and checking that there are no deformations. All tiles that are not planar must be rejected.
The tiles must be bagged vaccum-tight, all operations must be performed with gloved hands using poliethilene/nitrile powder free gloves. For the traceability of the process, the following requests need to be satisfied:
for the etching company:
· Eventual work instructions for the etching process traceability
· Etching date
· Bagging date
· Shipping date
· Batch number
· Batch surface roughness
· Certificate of conformance
· Date of arrival at Plyform
· Bag opening/primer application date
· Vacuum-tight re-bagging date
In order to evaluate tile cleanliness it has been decided to seal a single tile per batch in a vacuum-tight bag, to be used for the water break test, this last performed in Plyform with de-ionized water.
For the T-peel test, two tiles per production lot, cut in 1’’ wide stripes as per T-peel test already performed in Plyform, will be sealed in a vacuum-tight bag.
INFN must write the procedure for the removal of sheen from Kapton.
In order to avoid possible distorsion of the Kapton following bake-out at 60°C, INFN will comply to the following procedure:
· Hating of Kapton to 60°C in climatic chamber;
· Check of strip distance;
· Bake-out temperature definition.
1) Poliethilene cannot be employed on Heavy and Mid tray type moulds, due to protusions on tool.
2) There is a glue excess problem between tiles after the first bonding. Therefore, as per Plyform suggestion, excess glue on tiles and on interstices must be sanded to promote grip of the second bonding. Two roads can be followed:
· Leave the surface as is, although Plyform know-how dictates sanding of interface.
· Try to sand only excess glue on interstices between tiles?
Plyform will buy shortly a new bell jar dedicated to GLAST. Furthermore, the plates used for adhesive preparation must be employed for GLAST only. Plyform agrees to the glue de-gassing procedure.
Plyform agreed to introduce the use of wires in their bonding procedures. Such wires need not to be positioned beyond the tungsten tiles in order to avoid any contact with the Kapton.
Transportation of production into clean-room? Possibility to use a portable clean room (Clean-TentÓ, www.moorfield.co.uk ). For the tile-cleaning procedure, TexWipe 609 will be employed.
T-peel will be built as per Plyform standard practice (specimen cured at room temperature for 24 hours), and without control over adhesive thickness in order to be able to compare them with sandblasted ones. Furthermore, 6 specimen will be built with the following characteristics:
· 3 specimen cured for 24 hours; (for reference);
· 3 specimen cured for 24 hours at room temperature and then cured for another 24 hours at 40°C.
Finally, study of ASTM D2240-91 is mandated. Eventually, procurement of material required by the above-mentioned standard is mandated.
INFN must define the MIPs
· Tile conditions before usage;
· Kapton conditions before bonding
· Glue conditions before usage.