Please help identify a composite sheet product

Is the black surface a separate layer, like an adhesive intended for bonding to something else?

After such a long recent thread on Invar, I hesitate to suggest what that material could be, lest I look like a troll.

Could it be glass fiber?

I'm guessing it is a sample of material for one layer of advanced microelectronic packaging or interconnect, such as used for aerospace, military, and high-end commercial computer systems. I remember seeing ads for at least one company that used Invar as an inner layer reinforcement for multilayer circuit substrates, with copper used for the electrical interconnect layers on each side of the core.

The business is known generally as flex-circuit.

Which part? The metal core, the reinforced plastic tape, the whole assembly? Has it been coated with a lamination adhesive? Are you asking for the whole stack including the adhesive, all pre-made? Will you be buying any circuit layers with that? If you use somebody else's circuit layers, what if we can't guarantee our adhesive will stick?

The black layers are bonded to the stainless, but I'm not sure that it is intended for additional bonding. They have a striking similarity to a linen-based phenolic resin sheet material.

I was told by someone that the flexability of the material indicates that it probably is not phenolic resin, as it is too brittle for this application. They suggested it may be a high surface strength (mid- shore D) urethane product instead.

If anyone here is a troll, it's not someone who is trying to help out. I appreciate your thoughts.

I don't think it's glass fiber. It really looks like a linen product. No visible glass 'gleam' in the fibers at all.

There is no copper in here that I can see. I think it is not intended as an electrical or electronic product. I expect it is used more for mechanical applications, but I'm not sure about that.

I also doubt it is anything too exotic, as it would be too expensive in the application that I found it (a photographic application, but unfortunately, the person who developed the product is no longer with the living).

I'll look at the flex circult realm, but as I said, I don't think it is intended as an electronic product. It just doesn't have that look to it. It really looks to me like a coated stainless spring steel product, the coatings may be intended as wear surfaces, or to assist corrosion resistance.

Do these clarifications spur any thoughts at all?

---Michael

Are you looking for a thin walled steel backed self lubricating bearing? Try

bearing material of woven

polytetrafluoroethylene or PTFE fibers applied to a

rigid backing. To assure the best possible bond

between PTFE fibers and backing material, a

secondary, more readily bondable fiber (which may

vary with application requirements) is interwoven

with the PTFE fibers presented on the bearing side

of the fabric."

Don't know how the material is used -- that would give the best clue -- but you might want to do a Google search on "fishpaper". That's a slang term used for a stiff, but somewhat flexible dielectric used in numerous electronics applications to prevent accidental shorting . . . usually between sharp leads on the non-component side of a circuit card and other metal objects. The stuff is known by various other nomenclature, but "fishpaper" should lead you to that also. Lots of different kinds exist. Gray, white and black colors are common. With some kinds the stuff will begin to crack or exfoliate if you bend it sharply. Some other kinds will bend and spring back, and still others will readily deform (and stay deformed) to whatever shape you care to bend into it.

Mark 'Sporky' Staplet> The black layers are bonded to the stainless, but I'm not sure that it

Mark,

Thanks for the fishpaper recommendation. I don't think it is quite what I have here, but it may make a good alternate material. I'm not sure whether it will be a suitable alternate, but I will try to get some samples and see how it performs.

I guess the next question that I have is what is the possiblity that there is a manufacturer out there that would be able to make put a coating like this on some stainless spring steel? Can any one recommend a company that might be able to do this in small runs?

Thanks,

---Michael

David,

I'm not looking to use the sheets as bearing material, and I doubt that the sample I have is really intended for that, based on the texture of the surfaces.

Looking at the website you sent, I think it is a more complex product than I have, but I'll investigate it a little more and see what I can find out.

Thanks,

---Michael

SOME fishpaper I've seen bears a pretty close resemblance to what you've described -- a stiff material that's very springy, will not take a set, and has a coating of something like a phenolic resin over a woven mat of something (fiberglass?). What I've seen has been medium gray, but I know of other products that come in black. The stuff is tougher than shoeleather, and of course that's how it's meant to be. Identifying a specific product from a specific manufacturer would probably be difficult. BTW, in my experience it was mostly used in defense aerospace applications, but it doesn't seem to be used quite so much anymore, probably because better dielectrics are available which don't have a metallic center core and aren't so expensive to manufacture (polyimide, for example).

Hope that helps . . . but I'm afraid it won't.

Mark 'Sporky' Stapleton Watermark Design, LLC

Michael wrote:

Not to be to deadly technical, but you could help yourself.

Can you weigh the item?

Measure the dimensions of length, width and thickness?

Estimate the thickness of the surface coatings?

Someone keenly interested could then do some estimates of densities and make better guesses as to the composition of the stuff.

Otherwise, this guessing game with no data is a good example of one of the worst ways in which to practice materials technology..... a series of guessing games with no clues.

Jim

Mark,

I think you may be onto something with the recommendation.

I destructively tested one of the sheets I have, and discovered that the woven material does indeed look like fiberglass, and the metal in the middle is actually thinner than I thought. It is a foil, possibly aluminum. I don't have a way of accurately measuring the thickness, but it is probably .001 or less.

I managed to peel the three layers apart, so I have the foil and two outer layers completely seperate from each other in a small sample piece.

I measured a 4x4" square of the material, and weighed it. It comes in at 10.4 grams on my scale (which is accurate to a tenth). That equates to .65g per square inch, or 93.6g per square foot, at the .020 thickness.

I'm looking around a bit based on this new information, but web searches for fishpaper turn up lots of natural rubberized paper, but no synthetics that I can see.

I'll keep trying.

---Michael