I want to make my own silver/PTFE boards. Blank PTFE boards I've found are only copper-clad.
If I dissolve away the copper I'm not sure if the PTFE surface will need to be re-etched for bonding something else. Usually etchant is sodium in a carrier such as tetrahydrofuran. The THF I can distill from PVC bonding fluid, but I don't have a source of sodium (electrolysis of molten table salt is beyond my current capabilities). But if on the other hand the removed copper cladding leaves a bondable surface, then this may be an easy process. Silverplating would be an option if I could leave a small uniform thickness of the original copper cladding, but there's no way to etch that evenly.
If I dissolve away the copper I'm not sure if the PTFE surface will need to be re-etched for bonding something else. Usually etchant is sodium in a carrier such as tetrahydrofuran. The THF I can distill from PVC bonding fluid, but I don't have a source of sodium (electrolysis of molten table salt is beyond my current capabilities). But if on the other hand the removed copper cladding leaves a bondable surface, then this may be an easy process. Silverplating would be an option if I could leave a small uniform thickness of the original copper cladding, but there's no way to etch that evenly.
Hi
I would coat one side of the silver sheet with a teflon solution (see some examples here: http://www2.dupont.com/Teflon_Industrial/en_US/products/selection_guides/coatings.html), dry it at 110°C to remove any trace of solvent. The teflon and silver sheet should then be put in a press and heated at the recommended temperature to cure the teflon coating; hopefully, the coating will also bond to the teflon sheet. The silver sheet might have to be treated in order to promote adhesion, but this might involve highly dangerous chemicals, such as PFOA. I recommend you get more information on a specialized forum, such as finishing.com or groupsrv/science/materials.
LV
I would coat one side of the silver sheet with a teflon solution (see some examples here: http://www2.dupont.com/Teflon_Industrial/en_US/products/selection_guides/coatings.html), dry it at 110°C to remove any trace of solvent. The teflon and silver sheet should then be put in a press and heated at the recommended temperature to cure the teflon coating; hopefully, the coating will also bond to the teflon sheet. The silver sheet might have to be treated in order to promote adhesion, but this might involve highly dangerous chemicals, such as PFOA. I recommend you get more information on a specialized forum, such as finishing.com or groupsrv/science/materials.
LV
This is definitely NOT a diy operation. What needs to happen is a pretreatment of the PTFE surface with sodium naphthalide (or something similar) in THF. This solution can only be made and handled under strict anaerobic conditions (e.g., vacuum line and high quality glove box). Then the surface can accept cladding, which is usually done by coating the foil with a tie layer resin, then applying it to the PTFE using heat and pressure.
Nixie, what you're thinking of is the pretreat solution. VERY dry THF has naphthalene dissolved in it, then metallic sodium added. The naphthalide anion, a strong free radical, forms spontaneously and is a brilliant green color. It's also deadly toxic, corrosive, and in the presence of air or water, potentially explosive.
Nixie, what you're thinking of is the pretreat solution. VERY dry THF has naphthalene dissolved in it, then metallic sodium added. The naphthalide anion, a strong free radical, forms spontaneously and is a brilliant green color. It's also deadly toxic, corrosive, and in the presence of air or water, potentially explosive.
Tetra-Etch is sold in the exact same types of cans that PVC cement is sold in.SY said:
An externally hosted image should be here but it was not working when we last tested it.
Clearly intended to DIY. Instead of THF it uses 1,2-dimethoxyethane as the base and there's nothing about anhydrous conditions being necessary.
The reason I asked for DIY alternatives is because I didn't find a Canadian source yet for this.
I actually have all the hardware and vacuum, it's that I don't have a source of metallic sodium. It's available on eBay but importing is a problem.
Any ideas how to find a consumer source of etchant in my country?
What is it? I never heard of this before. Unless the material is extremely thin, wouldn't this counteract the benefits of teflon's dielectric properties?
Nixie said:
Instead of screwing around with stuff that could cause permanent personal damage ( packaging doesn't determine DIY-ness,btw) why not request a quote from a firm such as
this, (sometimes you can get free samples)
http://www.gsassociates.com/
and leave the nasty hazardous stuff to those with extensive experience dealing with such (I've messed with this and LOTS of other hazardous mat'ls, perchloric/permanganic/chromic mixes, pertechnetic acid, cyanides, RDX/PETN, HF/HNO3/Perchloric, you name it) and it's REAL EASY to get hurt. Take Sy's advise. Don't DIY with this stuff.
Good luck
John L.
patronizing..naw
no one is patronizing anyone... sorry if you feel that way. Nothing in your post indicates your extensive experience.. just trying to help.. and packaging doesn't imply diy as you indicated above... which doesn't re-inforce perceptions of competence
trying to prevent some disasters if others are reading this.. sheesh... what a short fuze...
forget it.
no one is patronizing anyone... sorry if you feel that way. Nothing in your post indicates your extensive experience.. just trying to help.. and packaging doesn't imply diy as you indicated above... which doesn't re-inforce perceptions of competence
trying to prevent some disasters if others are reading this.. sheesh... what a short fuze...
forget it.
The point is I came here with pretty specific questions, not seeking "let someone else do it, don't DIY" comments.
As for indicating my experience, I didn't do it because it comes off exactly the way your post did -- as bragging. It's not that my fuse is short, it's that after a lot of people set fire to it, it gets burned down eventually.
I still don't know what that "tie layer resin" is. What I found on the web is nothing related to PTFE.
As for indicating my experience, I didn't do it because it comes off exactly the way your post did -- as bragging. It's not that my fuse is short, it's that after a lot of people set fire to it, it gets burned down eventually.
I still don't know what that "tie layer resin" is. What I found on the web is nothing related to PTFE.
bragging..naw
not bragging either... I've seen enough diasters by diy-ers in industry and out, w/o the humility to know their own limitations...
if you've got such know how and equipment, why not sputter etch the ptfe and then evaporate/rf sputter a silver film onto the activated surface, followed by bonding/plating/whatever a thicker silver layer?
piece of cake, see?
wet processing is messy and has alot of gotchas to be successful...
good luck....
not bragging either... I've seen enough diasters by diy-ers in industry and out, w/o the humility to know their own limitations...
if you've got such know how and equipment, why not sputter etch the ptfe and then evaporate/rf sputter a silver film onto the activated surface, followed by bonding/plating/whatever a thicker silver layer?
piece of cake, see?
wet processing is messy and has alot of gotchas to be successful...
good luck....
In their bulk metal foil resistors whitepaper Vishay claim that sputtered material as used in film resistors creates much more current noise, so it's better to use foil... LOL of course I doubt it would make an audible difference, but then again I don't believe silver makes a difference over copper yet I'm using it...
Also, while I do have vacuum, I don't have a sputtering setup and I doubt I could get a nice flat coat that way. Whereas I have most things for any wet job.
If there were only a way to etch away an existing copper cladding to an exact minimal thickness, then I could plate it easily. I made a batch of silver nitrate just two months ago and would be perfect for the job.
Also, while I do have vacuum, I don't have a sputtering setup and I doubt I could get a nice flat coat that way. Whereas I have most things for any wet job.
If there were only a way to etch away an existing copper cladding to an exact minimal thickness, then I could plate it easily. I made a batch of silver nitrate just two months ago and would be perfect for the job.
silver plating
The coating you get from silver nitrate solution is gonna be pretty rough at any significant thickness over maybe 1/2 micron. Most silver baths are based on cyanide chemistry, with small amounts of grain refiners such as "turkey red oil", antimony, etc. added to control the deposit morphology. I guess you could burnish it, but the quality of pc board thickness silver w/o refiners is gonna be lousy.
The sputtered layer is thin, maybe 1/4 micron or so, only serves as a bonding layer followed up with more robust coatings by evaporation or electrodeposition.
Might be able to get an electroless (hydrazine or formaldehyde-reduced) silver film (as used for mirroring, etc) to stick to a stripped copper clad board, who knows... give it a try.
John L.
The coating you get from silver nitrate solution is gonna be pretty rough at any significant thickness over maybe 1/2 micron. Most silver baths are based on cyanide chemistry, with small amounts of grain refiners such as "turkey red oil", antimony, etc. added to control the deposit morphology. I guess you could burnish it, but the quality of pc board thickness silver w/o refiners is gonna be lousy.
The sputtered layer is thin, maybe 1/4 micron or so, only serves as a bonding layer followed up with more robust coatings by evaporation or electrodeposition.
Might be able to get an electroless (hydrazine or formaldehyde-reduced) silver film (as used for mirroring, etc) to stick to a stripped copper clad board, who knows... give it a try.
John L.
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.
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.
SY said:
Just remember, Nixie, that PTFE is on the list of beiing pretty darned carcinogenic, basically one of the worst inthe world, when you force it to decomposition. Which part of the whole thing here you are attempting to do, may require exatly that. Plus the chemicals involved are nasty solvents,and highly carcinogenic. Which is why the warnings. Guys working at volatile chemical plants every day, are under less risk than a DIYer messing with this stuff.
It's only carcinogenic if you exceed around 250*C, and I'm not going quite that far. Otherwise it's extremely inert. I use PTFE tape to seal the ground glass joints on my labware and it survives distillation of nitric acid without adding anything to the result.
What about using a roller instead of a press? A laser printer fuser roller is easy to reuse for this, adding another metal roller for the bottom as opposed to the rubber one, and replacing the halogen light bulb based heater inside the roller with a higher powered one to reach say 200*C. Hydraulics wouldn't be needed since the roller concentrates the pressure on a small line; instead, it would just take longer to process a board. The only problem I see is that the board may get a bit warped, or the foil torn.
If I dissolve the copper from a copper-clad PTFE board, would the surface be still activated and suitable for bonding, or would it need re-etching of the teflon?
What about using a roller instead of a press? A laser printer fuser roller is easy to reuse for this, adding another metal roller for the bottom as opposed to the rubber one, and replacing the halogen light bulb based heater inside the roller with a higher powered one to reach say 200*C. Hydraulics wouldn't be needed since the roller concentrates the pressure on a small line; instead, it would just take longer to process a board. The only problem I see is that the board may get a bit warped, or the foil torn.
If I dissolve the copper from a copper-clad PTFE board, would the surface be still activated and suitable for bonding, or would it need re-etching of the teflon?
I can generate high power air plasma. Would that etch the surface in the right way?
Or what about this Teflon bonding kit, is this likely to create a strong enough bond? http://www.usplastic.com/catalog/pr...splastic&category_name=12077&product_id=12176
A bit expensive at $73 for only 2-4 square feet...
Or what about this Teflon bonding kit, is this likely to create a strong enough bond? http://www.usplastic.com/catalog/pr...splastic&category_name=12077&product_id=12176
A bit expensive at $73 for only 2-4 square feet...
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