Attaching a really thin layer of aluminum to a really thin layer of mylar.

[silverpig]

I tell you, lithography + evaporation. I put 70 nm wide Cr and Au traces (got up to a few microns wide), that were about 30 nm thick (I could have gone for a micron easily), on 4 um of polyimide on a phosphor bronze substrate. Depending on the width of your traces you can just find a good photoplotting website with an insanely high dpi printer. Just send them a vector file of your pattern, they'll print it on a transparency for you and send it to you for something like $10.

Then, head on over to the mems exchange and you can probably get polyimide put on a silicon wafer, then photoresist, have them do the lithography and Al deposition. You'll have to figure out how to get the polyimide off the Silicon, but that may be easy if you just put a layer of photoresist underneath the polyimide. When they do the liftoff process after evaporating the Al to remove the photoresist mask, the resist underneath the polyimide will also dissolve, freeing your film. This film will be really flimsy though and it will be floating in liquid so I really don't know what you'll be doing with it or how you'll proceed from there.

 

[hanoverphist]

Originally posted by: Cheesehead

Originally posted by: CycloWizard
That's potentially very tricky. Do you need a uniform adhesive film between the two layers? How much weight is too much? And, of course, how big are the pieces that you're attaching?

Simple cyanoacrylate (common ingredient in superglues) will bond just about anything under the right conditions without adding much weight. However, if the sheets you're bonding are large enough, it won't cure properly because it will be oxygen-starved in interior regions. There are pressure-sensitive adhesives that might be perfect for your application, but they are more expensive and require more advanced processing techniques as well.

The pieces will be up to 4" x 4", making the problem of oxygen starvation a big one. While a uniform adhesive film is not required, I don't want any traces lifting up off of the mylar after I etch it.

If anyone's wondering, I'm currently trying to replicate both the Take.T air motion transformer headphones and the old version Fostex T50 orthodynamic headphones (which are nothing like the new ones.) To do so, I need a very light diaphragm covered with many very thin conductive traces to create a magnetic field.

This is easier said than done, which is why I'm here.

why not look into conductive inks and have it silk screened on? i did a similar ground strip for the first gen air tasers here in arizona. it was a pain to figure out the thickness and process, but once it was all done we ended up with a piece of plastic (the yellow door on the front) that had a screened strip of conductive metalized ink on the backside that provided the contact for the ejection of the electrodes. id think screening large pieces of mylar and cutting them down would be a cost effective solution for ya.

 

[Sho'Nuff]

A while back, when I used to work for a certain government organization, I used to buy metallized kapton film from a vendor and then use photolithography to make a plurality of traces. So, you might want to try buying aluminized kapton and then etching the purchased product. There is no need to recreate the wheel if you don't have to.

Also while at said government organization, I used electroless deposition to deposit certain metals and metal alloys on kapton and other polymeric films and etched the resultant product as described above. If the adhesion of the metal was poor, I would pop the metal film off of the polymer with ultrasound to produce randomly shaped high aspect ratio particles that were useful for certain purposes.

 

[silverpig]

Originally posted by: soxfan
A while back, when I used to work for a certain government organization, I used to buy metallized kapton film from a vendor and then use photolithography to make a plurality of traces. So, you might want to try buying aluminized kapton and then etching the purchased product. There is no need to recreate the wheel if you don't have to.

Also while at said government organization, I used electroless deposition to deposit certain metals and metal alloys on kapton and other polymeric films and etched the resultant product as described above. If the adhesion of the metal was poor, I would pop the metal film off of the polymer with ultrasound to produce randomly shaped high aspect ratio particles that were useful for certain purposes.

The nice thing is a lot of photoresist developers are aluminum etchants

 

[cheesehead]

Originally posted by: hanoverphist


why not look into conductive inks and have it silk screened on? i did a similar ground strip for the first gen air tasers here in arizona. it was a pain to figure out the thickness and process, but once it was all done we ended up with a piece of plastic (the yellow door on the front) that had a screened strip of conductive metalized ink on the backside that provided the contact for the ejection of the electrodes. id think screening large pieces of mylar and cutting them down would be a cost effective solution for ya.

Looked into it. The conductivity is generally pretty poor for these inks, and making sufficiently thin traces would be a drag.

Originally posted by: soxfan
A while back, when I used to work for a certain government organization, I used to buy metallized kapton film from a vendor and then use photolithography to make a plurality of traces. So, you might want to try buying aluminized kapton and then etching the purchased product. There is no need to recreate the wheel if you don't have to.

Any chance you could recommend a place I could buy this?