110 likes | 232 Views
Thin metal strips for MM resistive anodes. ~ The way for fine pitch strips ~. Atsuhiko Ochi Kobe University. Requirements for resistive strips. Readout strips. High resistivity (a few MΩ/line) Mass production available for large size Fine pitch
E N D
Thin metal strips for MM resistive anodes ~ The way for fine pitch strips ~ Atsuhiko Ochi Kobe University
Requirements for resistive strips Readout strips • High resistivity (a few MΩ/line) • Mass production available for large size • Fine pitch • Less than half of readout strip pitch is preferable • We do not need to care alignment between readout and resistive strips. Resistive strips A.Ochi, MM meeting
For “stereo readout” Pitch of resistive strips = ½ readout strips • Fine strips will be required strongly for stereo readout • For improving position resolution along eta direction. Pitch of resistive strips = Readout strips A.Ochi, MM meeting
Researches for production methods for resistive strips • Screen printing is one of hopeful method. • However, there are some difficulty remained ... • Fine pitch of the strips • 400 mm spacing was ok • Test chamber has been worked well at beamtest. • However, how about 200 mm pitch? • We (Kobe and ICEPP) have tried other ways to make fine pitch • Strip drawing by dispenser • Thin metal sputtering with photo resist mask • We got very good result in second way. A.Ochi, MM meeting
2nd approach:Thin metal spattering • Spattering metal on a substrate provides high resistivity (~1MW/sq.) • Industrially, spattering process is available using large chamber. • f1800 mm x H2000 mm • Maximum board size: 1m x 4.5m (flexible board) A.Ochi, MM meeting
Production process Photo resist (reverse pattern of surface strips) • Very fine structure (a few tens micro meter) can be formed using photo resist. (same as PCB) • We will make a first test in this February Substrate (polyimide) Metal spattering Substrate (polyimide) Developing the resists Substrate (polyimide) A.Ochi, MM meeting
Delivered sample • 10cm X 10cm, 400mm pitch • Surface resistivity is about 6 MW/sq. • These strips are formed on thin polyimide film A.Ochi, MM meeting
Basic properties of resistive foil • Strip patterns are very fine and uniform. • The precision of the pattern is less than 5mm • This means, 200μm or less pitch will be available • Resistivity is uniform • Attachment of patterns on the substrate is very tough • Resistivity is not change when rubbed by paper. • Substrate can be bent without damage of resistive layer • Please see and touch a real sample !! X1000 microscopic picture A.Ochi, MM meeting
Possible option for MAMMA production • We can divide the production process of resistive strip from that of readout board. • Resistive strip is formed on thin foil • Because of fine pitch, < 200 micron, we don’t need fine alignment between resistive strips and readout strips. • Dividing those processes will make the yield of production growing up. A.Ochi, MM meeting
Prototype production • We are making 200 micron strip sample • Strip type is brick type • Surface resistivity will be going down • around 100kW/sq. • This correspond to 10MW/cm • This sample will be delivered at end of March 20mm A.Ochi, MM meeting 0.20mm
Our proposal to next step • MM test board (small size) using sputtered strips foil and CERN readout board (whether existing type or stereo type) • I need to discuss with Rui. • If production and testing are well, we will make large size MMs using similar scheme. A.Ochi, MM meeting