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[Thomas K Hemmick <tkhemmick AT gmail.com>]

ENIG is a circuit card company process.  I looked it up and it is not for the amatuer.  In this case the new layup would have to be:

FR4 (5 mil)

Cu (1/4 oz...this is special order in industry and the thinnest you can buy)

Nickel

Au

Al-stripes

The Nickel and Au are really really thin.  This is an industry standard (originally a military spec).  The Ni provides a diffusion barrier (otherwise Cu migrates through Au) and the Au is chemically non-reactive and has a high work function: 

Laser is 266 nm or 4.7 eV  The Au adds basically no radiation length and is MUCH better than copper for also not yielding a photo-electron.

Tom

On Tue, Oct 22, 2019 at 5:48 PM Tarafdar, Sourav <sourav.tarafdar AT vanderbilt.edu> wrote:

Hi Tom,

Thanks for the info. So if I understand correctly the design flow of honeycomb membrane

Is something like Al layer -à Cu layer -à ENIG with Al stripes ?

I think we should include ENIG with Al stripes detail as well. Is there any engineering drawing that is available ? Probably getting into G4 simulation for ENIG with Al stripes will be tough before QM19.

Thanks,

-Sourav

 

From: Thomas K Hemmick <tkhemmick AT gmail.com>
Reply-To: "tkhemmick AT gmail.com" <tkhemmick AT gmail.com>
Date: Tuesday, October 22, 2019 at 4:40 PM
To: "Greene, Senta V" <senta.v.greene AT Vanderbilt.Edu>
Cc: "sphenix_tpc_general AT skipper.physics.sunysb.edu" <sphenix_tpc_general AT skipper.physics.sunysb.edu>
Subject: Re: QM19 Central Membrane poster

 

Hi Vicki

 

Looks nice.  There is an update.  The coated with aluminum is updated to commercial ENIG with Al stripes.  The rad length of the ENIG over 1/4-OZ copper is not significantly different that the prior plan, but the gold work function is really high and eliminates the background electrons that would have come during a diffuse laser flash during calibration.  We are making right now (orders are out since Friday) a test piece for the small 10x10x10 cm^3 TPC in Bob Azmoun's lab.

 

This updates post-dates our most recent TPC general meeting and comes out of the TPC laser calibration meeting...

 

Tom

 

On Tue, Oct 22, 2019 at 1:41 PM Greene, Senta V <senta.v.greene AT vanderbilt.edu> wrote:

Hi all,

I am attaching a draft of the poster I propose to present at QM19 covering the TPC central membrane simulations.  Please review, comment, and (hopefully) approve as soon as possible, since I will leave for China on Wednesday, October 30.

Many thanks,
Vicki