Atsuhiko Ochi Kobe University 28 August 2012 ATLAS muon chambers R&D on micromegas meeting

 Screen printing is suitable technique for large size board.  Very simple step to make it. ◦ Current production way of the MM strips.  Making pattern (negative) of strips.  Painting the resistive ink.  Scraping surface.  Etching the negative pattern ◦ Our proposal of new production  Printing the resistive strips.  That’s all!!  Edge of strips will be rounded. ◦ More stable operation will be expected. Etching methodPrinting method 2012/8/28 A. Ochi, Kobe Univ.2

Printing technique that uses a woven mesh to support an ink-blocking stencil It is common technology for large size printing. Many type of inks can be used. Thick printing is available (a few – 100 microns) /8/28 A. Ochi, Kobe Univ. squeegee frame Screen ink stencil

2012/8/28 A. Ochi, Kobe Univ.4 Screen printing machine Screen Printed strips on a polyimide film Putting the ink (resistive polyimide) on the screen Now printing …

 Resistive material ◦ “Resistive Polyimide”, made by Toray.  We are contacting with Toray people to improving the material.  This material is not provided commercially.  Curing step (90 – 350 degree) is needed.  Art work and printing ◦ Made by Raytech Inc. ◦ Metal screen with polyimide stencil was used.  Size of prototype ◦ 10cm X 10cm with 400 micro meter pitch. 2012/8/28 A. Ochi, Kobe Univ.5

 Using typical screen printing method ◦ Screen: Polyester ◦ Stencil: Sensitive emulsion  Results ◦ First print was good. ◦ From second print… Very bad quality. ◦ We are using NMP (n-methyl- pyrrolidine) to clean up the screen, however, it dissolves also emulsion pattern.  We need other screen type!! Printing pattern (first one) Dissolved emulsion pattern 2012/8/28 A. Ochi, Kobe Univ.6

 A special screen was made ◦ Made from polyimide film with copper foil (with 40 micron of nickel plating.) ◦ Screen: Copper and nickel ◦ Stencil: Polyimide (50 micro meter thickness)  Results ◦ Bad quality ◦ Too many ink are printed, and strips are bleeded.  Need thinner stencil Polyimide Printing inks are stored in this space. 2012/8/28 A. Ochi, Kobe Univ.7

 Making thinner stencil: ◦ Stencil: polyimide (25 micron)  Results ◦ Some of samples have better quality. ◦ Resistivity: 10M  /cm ◦ But, the inks are still too much.  More more thinner stencil is need Microscopic Picture of printed strips (good quality sample) 2012/8/28 A. Ochi, Kobe Univ.8

 Making moreover thin stencil: ◦ Stencil: polyimide (13 micron)  Results ◦ The amount of ink is good ◦ There are some good samples ◦ However some bleedings are found  Sometimes, screen of all printing area was attached while printing. It should be attached only squeegee is on it.  The screen parameters are almost OK.  Remained problems are parameter settings of screen tension and squeegee pressure. 2012/8/28 A. Ochi, Kobe Univ.9 10cm 2mm

2012/8/28 A. Ochi, Kobe Univ.10

 We have started to make a resistive strips using screen printing method.  We have tried to several times to print, and we are achieving to good condition for production.  We will make a MicroMEGAS test board just after screen printing technique will be established. ◦ Using bulk MM technique. ◦ We will make prototype in this September or October. (Manufactured by Laytech Inc.)  Large size printing machine (or hand printing equipment) should be newly-prepared. 2012/8/28 A. Ochi, Kobe Univ.11