Nixie
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How to create silver cladding on PTFE substrate?
I need to either bond silver foil, or plate silver, onto a (flat) teflon substrate. How can I do this? The bond must be quite strong.
[Edited on 11-1-2007 by Nixie]
\"Good is a product of the ethical and spiritual artistry of individuals; it cannot be mass-produced.\" --Aldous Huxley
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Eclectic
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You'll need to treat the surface of the Teflon to make it bondable.
There are liquids commercially available to do this, consisting of a solvated alkali metal, generally a complex of naphthaline and sodium in aromatic
solvent.
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Nixie
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Can I purchase these as a hobbyist?
Also I'm reading open containers don't last well due to exposure to the atmosphere. Seems DIYing a small amount would be better. But I don't have a
source of metallic sodium...
Additionaly, after treating the teflon, what bonding substance do I use?
[Edited on 12-1-2007 by Nixie]
\"Good is a product of the ethical and spiritual artistry of individuals; it cannot be mass-produced.\" --Aldous Huxley
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indigofuzzy
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Would bonding the foil with cyanoacrylate work? Or does super glue not work on teflon?
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Nixie
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I asked this elsewhere, and got the following reply:
| Quote: | For PTFE, a tie layer resin is often an uncured resin like a phenoxy or polyimide layered in, something that will bond to the activated PTFE surface
and the foil under extreme heat and pressure. It's usually pretty thin so it doesn't make an enormous impact on the dielectric properties of the
board.
The can o' stuff won't be nearly sufficient to get Teflon to bond a foil layer that will stand up to flexing and heat. You really do need a STRONG
free radical source (not to mention a press that will take the resins to a cure state and apply enough pressure), and that means specialized
techniques and equipment.
Or you could do what auplater suggests, do a sputtered or CVD conductive layer, then plate it up to the thickness you need.
This is not diy stuff. |
Plating is fine, though I'd rather use actual silver foil. I have vacuum but not the other tools necessary for sputtering. But does anyone have
detailed information on this tie layer resin thing? Surely there must be a way to DIY silver on PTFE without equipment that would be unreasonable to
build oneself.
I can find copper-clad PTFE boards, and if there was some way to remove the vast majority of copper thickness very evenly so then I could plate on
silver such that it would have the majority of the thickness... but I see no way to get such an even etch depth of the copper.
\"Good is a product of the ethical and spiritual artistry of individuals; it cannot be mass-produced.\" --Aldous Huxley
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Eclectic
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You can try etching off all the copper, then see if the surface is reactive enough to take an thin chemically deposited flash plating and replate to
desired thickness...
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Mr. Wizard
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You might try the low tech method of using some gold leaf on the base material and then plating a real silver layer onto it. The hobby sections of
many stores carry a 'gold leaf' that is actually aluminum foil, but it may still work. If it doesn't you can still try real gold leaf. Of course, the
bond won't be any better than the original glue or size used to adhere the leaf.
A more aggressive approach, with higher tech requirements would be sputtering or vapor depositing in a vacuum chamber.
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Nixie
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I'm wondering actually whether a hot roller could be used instead of a press as mentioned in what I quoted in the previous post. That would make it
much easier to apply high pressure, and I can easily modify a laser printer fuser roller to reach over 200*C and higher pressure (instead of rubber
roller for the bottom use another metal roller; the heater element in the printer fuser is just a high-power halogen light bulb). Though the PTFE
board is more likely to warp that way.
\"Good is a product of the ethical and spiritual artistry of individuals; it cannot be mass-produced.\" --Aldous Huxley
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tnhrbtnhb
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hm.... I wonder how the copper is attached to the PTFE? If it's an adhesive resin, suppose you could dissolve the copper off and simply clean the
adhesive and apply silver foil in place of copper? The adhesive will not melt at 200 deg, though, it has to withstand soldering. PTFE won't warp at
200 either.
heck, if all you want is the product, you can probably buy it from somewhere.
I don't think you'll get a strong, bond, though, without expensive surface treatments. One way to "activate" the surface that I've read about is to
treat it with atomic oxygen.... so basically a high enough intensity UV light shone on the surface, I suppose it might take prohibitively long,
though....
Or take teflon circuit board, take the copper and whatever adhesive is on there off (if there is something), and condense a thin film of mercury on
it, then electroplate. Kinda hazardous, though. Maybe gallium instead. Primitive metal vapor deposition isn't all that hard, you don't even need a
vacuum.
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Eclectic
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Check USPlastics for a Teflon bonding kit.
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Nixie
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I am able to create high power air plasma (not arc, glow discharge). Perhaps that would prep the surface well.
I have a vacuum but I'm still not sure how to do vapor deposition given that.
\"Good is a product of the ethical and spiritual artistry of individuals; it cannot be mass-produced.\" --Aldous Huxley
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