Looking for somewhat flexible metallized film

[Joerg]

Folks,

Here is what we want to do. Stretch a film over some dielectric material
which has varying properties. Then a water- or air-filled balloon is
pressed onto that, and this presses the film against the dielectric. The
more pressure, the more dielectric is touched. Width of dielectric is a
few inches, pressure doesn't matter (by hand). There is an electrode on
the other side of the dielectric.

So the plastic must be somewhat flexible for up to 5% of sag and I guess
that rules out Mylar and Kapton. Also, the metallization should be
non-oxidizing which usually means gold or similar. The surface roughness
must be as low as possible, low single-digit nanometers.

Does anyone know a supplier for such film that sells in quantities less
than truckloads?

 

[Jamie M]

Folks,

Here is what we want to do. Stretch a film over some dielectric material
which has varying properties. Then a water- or air-filled balloon is
pressed onto that, and this presses the film against the dielectric. The
more pressure, the more dielectric is touched. Width of dielectric is a
few inches, pressure doesn't matter (by hand). There is an electrode on
the other side of the dielectric.

So the plastic must be somewhat flexible for up to 5% of sag and I guess
that rules out Mylar and Kapton. Also, the metallization should be
non-oxidizing which usually means gold or similar. The surface roughness
must be as low as possible, low single-digit nanometers.

Does anyone know a supplier for such film that sells in quantities less
than truckloads?

Hi,

Aluminized mylar is pretty common, not sure if it will stretch
5% though!

Ebay has quite a bit:
http://www.ebay.ca/sch/i.html?_nkw=mylar+rolls

cheers,
Jamie

 

[Joerg]

Hi,

Aluminized mylar is pretty common, not sure if it will stretch
5% though!

Ebay has quite a bit:
http://www.ebay.ca/sch/i.html?_nkw=mylar+rolls

Mylar is tough to stretch. We could probably do it somehow but aluminum
metallization can develop a fine non-conductive layer quickly and has a
pretty bad surface roughness.

 

[Phil Hobbs]

Folks,

Here is what we want to do. Stretch a film over some dielectric material
which has varying properties. Then a water- or air-filled balloon is
pressed onto that, and this presses the film against the dielectric. The
more pressure, the more dielectric is touched. Width of dielectric is a
few inches, pressure doesn't matter (by hand). There is an electrode on
the other side of the dielectric.

So the plastic must be somewhat flexible for up to 5% of sag and I guess
that rules out Mylar and Kapton. Also, the metallization should be
non-oxidizing which usually means gold or similar. The surface roughness
must be as low as possible, low single-digit nanometers.

Does anyone know a supplier for such film that sells in quantities less
than truckloads?

You're going to want to use conductive ink for that, not a metal film.
The metal will crack into a zillion tiny islands. Good-grade carbon ink
will stick to low surface energy substrates such as teflon or
polyethylene, and is tough enough to take a hard crease without cracking.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

 

[RobertMacy]

Mylar is tough to stretch. We could probably do it somehow but aluminum
metallization can develop a fine non-conductive layer quickly and has a
pretty bad surface roughness.

That single annometer roughness is pretty tough to meet. But have you
looked at the food industry? Like Lay's potato chips come in a pretty thin
metallized film.

 

[Joerg]

I don't think that "potato chip film" stretches.

Some does, a little. But they mostly have the same problem as party
balloons: Another non-conductive coating to make them shiny or have a
"wet" look. It's all about shelf appeal. Buy me, buy me, be hungry,
salivate, be hungry, now, must buy, must buy.

 

[Joerg]

You're going to want to use conductive ink for that, not a metal film.
The metal will crack into a zillion tiny islands. Good-grade carbon ink
will stick to low surface energy substrates such as teflon or
polyethylene, and is tough enough to take a hard crease without cracking.

Good idea. Do you know where one could buy such material ready-to-go off
the shelf? Price is not important unless it's really outlandish, because
this is only for a materials test station.

I've looked at carbon nanotube material which could almost get there in
terms of surface roughness. But it only existed on glossy print, not on
a shelf with a price tag on there.

 

[RobertMacy]

.,snip...
Some does, a little. But they mostly have the same problem as party
balloons: Another non-conductive coating to make them shiny or have a
"wet" look. It's all about shelf appeal. Buy me, buy me, be hungry,
salivate, be hungry, now, must buy, must buy.

Isn't metallized mylar used to prevent the helium from escaping, not for
the looks?

 

[Mikko Syrjalahti]

Here is what we want to do. Stretch a film over some dielectric material
which has varying properties. Then a water- or air-filled balloon is
pressed onto that, and this presses the film against the dielectric. The
more pressure, the more dielectric is touched. Width of dielectric is a
few inches, pressure doesn't matter (by hand). There is an electrode on
the other side of the dielectric.

Does the film have to be metallic or just conductive ? A finnish company
called Canatu manufactures carbon nanotube coated films, which might be
suitable. Their main substrate is PET, but they might have something
more stretchable, too.

 

[Joerg]

Isn't metallized mylar used to prevent the helium from escaping, not for
the looks?

No idea but definitely also for looks. There were shiny golden ones and
silver ones.

 

[Joerg]

Does the film have to be metallic or just conductive ? ...

Only conductive and that doesn't even have to be very good. A few
hundred ohms corner to corner would be ok. I also does not matter
whether it's translucent or not. But surface roughness is a key
parameter. If that is more than very few nanometers the whole testing
idea isn't going to work.

... A finnish company
called Canatu manufactures carbon nanotube coated films, which might be
suitable. Their main substrate is PET, but they might have something
more stretchable, too.

Aha, now we are getting somewhere. Thanks!

http://www.canatu.com/products/

 

[Spehro Pefhany]

Folks,

Here is what we want to do. Stretch a film over some dielectric material
which has varying properties. Then a water- or air-filled balloon is
pressed onto that, and this presses the film against the dielectric. The
more pressure, the more dielectric is touched. Width of dielectric is a
few inches, pressure doesn't matter (by hand). There is an electrode on
the other side of the dielectric.

So the plastic must be somewhat flexible for up to 5% of sag and I guess
that rules out Mylar and Kapton. Also, the metallization should be
non-oxidizing which usually means gold or similar. The surface roughness
must be as low as possible, low single-digit nanometers.

Does anyone know a supplier for such film that sells in quantities less
than truckloads?

< 10nm is < 0.5 microinch (not sure if you're talking RMS or AA, but
it's very smooth in any case). So you're looking for optical grade
film.

Maybe ITO or gold on PET would work, but this paper indicates that
your 5% may not be achievable without cracking:

http://ieeexplore.ieee.org/xpl/logi...re.ieee.org/xpls/abs_all.jsp?arnumber=5936492

Could you use gold leaf bonded to a flexible optical-grade film?

 

[Spehro Pefhany]

I don't think that "potato chip film" stretches.

...Jim Thompson

PET has a Young's modulus of around 2.5 GPa, and elongation at yield
of > 15%.

 

[Spehro Pefhany]

Some does, a little. But they mostly have the same problem as party
balloons: Another non-conductive coating to make them shiny or have a
"wet" look. It's all about shelf appeal. Buy me, buy me, be hungry,
salivate, be hungry, now, must buy, must buy.

They're really concerned about keeping the chips airtight to get long
and consistent shelf life. I did some work for a company that makes
the packaging materials years ago.

 

[Joerg]

< 10nm is < 0.5 microinch (not sure if you're talking RMS or AA, but
it's very smooth in any case). So you're looking for optical grade
film.

Maybe ITO or gold on PET would work, but this paper indicates that
your 5% may not be achievable without cracking:

http://ieeexplore.ieee.org/xpl/logi...re.ieee.org/xpls/abs_all.jsp?arnumber=5936492

Could you use gold leaf bonded to a flexible optical-grade film?

If we can't get 5% we could back off to maybe 3% or less but the real
challenge seems to be the surface roughness spec for the metallization.
It has to be in the low single-digit nanometers. We can do that in-house
but it would be a major effort that we are trying to avoid for a one-off
test station.

 

[Joerg]

They're really concerned about keeping the chips airtight to get long
and consistent shelf life. I did some work for a company that makes
the packaging materials years ago.

I am sure they do that as well. But when talking to a packaging designer
I was amazed how much effort goes into the glitz factor. IIRC he was a
very highly paid guy and had the freedom only real artists are afforded.

 

[Phil Hobbs]

They're really concerned about keeping the chips airtight to get long
and consistent shelf life. I did some work for a company that makes
the packaging materials years ago.

Yup. Gas diffusion in metal is many orders of magnitude slower than in
plastic.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

 

[Jasen Betts]

So the plastic must be somewhat flexible for up to 5% of sag and I guess
that rules out Mylar and Kapton. Also, the metallization should be
non-oxidizing which usually means gold or similar. The surface roughness
must be as low as possible, low single-digit nanometers.

you're looking for a metal that can deforem 5% elastically ?
if the matal can;t handle the deformation it'll come off the film.

I've seen metalised PE used in wine bladders.
I don't know it if can handle 5% though.

 

[Joerg]

you're looking for a metal that can deforem 5% elastically ?
if the matal can;t handle the deformation it'll come off the film.

I've seen metalised PE used in wine bladders.
I don't know it if can handle 5% though.

We can go lower than 5% if needed. The main problem is surface roughness
which needs to be very few nanometers. We've got a process in-house that
can do this but it can't make such large films and it is very labor
intense to do that just for a test station.

 

[George Herold]

We can go lower than 5% if needed. The main problem is surface roughness
which needs to be very few nanometers. We've got a process in-house that
can do this but it can't make such large films and it is very labor
intense to do that just for a test station.

Hi Joerg, nanometers sounds hard! (But I really don't know.) Is this thing going to live in vacuum? For optics I always figured the scratch and digs are in the few micron range. (You've got to be able to see them after all.)

I think a monolayer of water on your surface will be in the nanometer range.

George H.