R&D of resistive stripsusing screen printing

Atsuhiko OchiKobe 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.

Motivations

Etching method Printing method2012/8/28A. Ochi, Kobe Univ. 2

Screen Printing• 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).

32012/8/28A. Ochi, Kobe Univ.

squeegee

frame

Screen ink stencil

Screen Printing

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Screen printing machine

Screen Printed strips ona polyimide film

Putting the ink (resistivepolyimide) 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.

Condition of the printing

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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!!

First trial (29th June)Printing pattern (first one)

Dissolved emulsion pattern

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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

Second trial (13th July)Polyimide

Printing inks are stored in this space.

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Making thinner stencil:◦ Stencil: polyimide (25

micron) Results

◦ Some of samples have better quality.

◦ Resistivity: 10MW/cm◦ But, the inks are still too

much. More more thinner

stencil is need

Third trial (26th July)Microscopic Picture of printed strips(good quality sample)

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4th trial (20th August) 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.

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10cm

2mm

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Microscopic pictures of printed strips

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.

Summary in current status

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Future prospects