Hi Eric,
You can cut open low resistance power capacitors to get some materials to experiment with. You will likely find 2-5 microns of aluminum sputtered to 5-15 micron polyimide or mylar.
From my experiments, sputtered metals are "noisier" then well designed metal foil laminates, but are much lighter and easier to obtain. Sputtered metals can be found in high enough resistance/square to avoid the need for a transformer.
The high magnetic forces in a ribbon can easily de-laminate a metal-film and create a buzzzz. This is a common discussion point on Magnepan forums.
You can cut open low resistance power capacitors to get some materials to experiment with. You will likely find 2-5 microns of aluminum sputtered to 5-15 micron polyimide or mylar.
From my experiments, sputtered metals are "noisier" then well designed metal foil laminates, but are much lighter and easier to obtain. Sputtered metals can be found in high enough resistance/square to avoid the need for a transformer.
The high magnetic forces in a ribbon can easily de-laminate a metal-film and create a buzzzz. This is a common discussion point on Magnepan forums.
Eric12 said:
I have used laminates that are made for the 'flexi' pcb industry.
Companies such as Espanex and Toray make these .
The thinest polymide substrate they use appears to be 9 micron.
Unfortunately they use copper rather than aluminum cladding,
but thickness can be as little as 3 micron with products from Toray.
The above makers use adhesiveless techniques for bonding the copper.
Another down side is obtaining small sample quantities, this can be near impossible with some of the very thin laminates that
tend to be used less often by mass producers.
This company makes aluminum laminates:
http://www.gts-flexible.co.uk/index.htm
But they do use adhesive to bond the materials, which can add
unwanted thickness/weight.
Good luck
Setmenu
Try
http://www.modelresearchlabs.com/products.htm
It's a site dedicated to RC model airplane builders. They have multiple types of mylar down to 1.5 micron thickness--some of it metalized, graphite "pulltrusions", boron... I can't guarantee they have what you want, but they do have related fun stuff for the tinkerer.
http://www.modelresearchlabs.com/products.htm
It's a site dedicated to RC model airplane builders. They have multiple types of mylar down to 1.5 micron thickness--some of it metalized, graphite "pulltrusions", boron... I can't guarantee they have what you want, but they do have related fun stuff for the tinkerer.
Try
info@apogeeribbons.com
They make high grade apogee spare parts and can also make the most complicated custom made ribbon to order, All Kapton/ALU. Quality is very good comes with a price.
info@apogeeribbons.com
They make high grade apogee spare parts and can also make the most complicated custom made ribbon to order, All Kapton/ALU. Quality is very good comes with a price.
Magnepan uses 2.5 micron aluminum for its long, 0.2" wide ribbon tweeters. The Magnepan user site has several posts about broken ribbons, so 2.5 microns is probably the thinnest pure aluminum usable for a robust tweeter design. I have a section of a Magnepan ribbon and it easily breaks with handling or a strong puff of breath. There are several ribbon microphones that also use 2.5 micron aluminum.
Sputtering very thin aluminum on a 2 micron thick mylar film will create a more physically robust ribbon than pure aluminum, but also a low efficiency ribbon relative to its weight since the electrical resistance will be much higher than 100% AL. Most ribbons are also corrugated(pleated) to increase horizontal stiffness. A thin mylar film ribbon may not hold this corrugation, and the ribbon is likely to "fold" from the magnetic field gradients.
Most commercial tweeters seem to use 8-10 micron aluminum, as this holds a corrugation well and is a good compromise between weight and physical robustness. 5.4 micron thick pure aluminum foil is thinnest I use on long, wide bandwidth ribbons.
Sputtering very thin aluminum on a 2 micron thick mylar film will create a more physically robust ribbon than pure aluminum, but also a low efficiency ribbon relative to its weight since the electrical resistance will be much higher than 100% AL. Most ribbons are also corrugated(pleated) to increase horizontal stiffness. A thin mylar film ribbon may not hold this corrugation, and the ribbon is likely to "fold" from the magnetic field gradients.
Most commercial tweeters seem to use 8-10 micron aluminum, as this holds a corrugation well and is a good compromise between weight and physical robustness. 5.4 micron thick pure aluminum foil is thinnest I use on long, wide bandwidth ribbons.
ericpeters said:
This is the accepted norm but is it an absolute truth?
The mesh will not stop dust partials and other air bourn impurities that will find themselves a nice home on the film, you can clean them off if you like
while I look through my fingers.LineSource said:
I believe you're correct that Mylar could not hold the pleats and it would not enhance the surface strength.
Plastics have to have some formula that is perfect for this application, no doubt it will be a complex material and will take 100 lab hours to make 0.5 grams of super thin strong plastic, flexible and rigid
a ghost like film that is there but not there if you will.
Hi Paradise_Ice
Dupont Mylar and Kaladex Polyester films, and Dupont Kapton Polyimide film are probably the most commonly used materials for planar and ribbon speakers.
Dupont Mylar has a Glass Transistion temperature Tg of 80 C
Dupont Kaladex has a Glass Transistion temperature Tg of 122 C
Dupont Kapton has a Glass Transistion temperature Tg of 360 C
Mylar can be found down to 2 microns in thickness, and 2.5, 3.6, and 5.0 micron mylar is pretty easy to find. The low Tg makes it a poor choice for high power metal-film laminates
Kaladex is harder to find below 7.6 micron thickness. Many new planar and ribbon speakers have converted from mylar to Kaladex films for the higher Tg.
Mylar and Kaladex are pretty "quiet" when you vibrate them.
Kapton is easy to get at 7.6 micron. 3.8 micron is also made by Dupont, but you may have to go directly to Dupont for purchase. Kapton's high Tg and melting point of over 400 C make it a very good material for high power planar and ribbon speakers. Kapton is also a good substrate for sputtering metals like Aluminum or copper. Many flexible PC boards use Kapton, as it is safe to solder to without special materials.
Kapton is a little "noisy" when you vibrate it.
There are a wider range of adhesives for Mylar/Kaladex than for Kapton.
mylar 1360 kg/m3
kapton 1535 kg/m3
Aluinum 2700 kg/m3
Dupont Mylar and Kaladex Polyester films, and Dupont Kapton Polyimide film are probably the most commonly used materials for planar and ribbon speakers.
Dupont Mylar has a Glass Transistion temperature Tg of 80 C
Dupont Kaladex has a Glass Transistion temperature Tg of 122 C
Dupont Kapton has a Glass Transistion temperature Tg of 360 C
Mylar can be found down to 2 microns in thickness, and 2.5, 3.6, and 5.0 micron mylar is pretty easy to find. The low Tg makes it a poor choice for high power metal-film laminates
Kaladex is harder to find below 7.6 micron thickness. Many new planar and ribbon speakers have converted from mylar to Kaladex films for the higher Tg.
Mylar and Kaladex are pretty "quiet" when you vibrate them.
Kapton is easy to get at 7.6 micron. 3.8 micron is also made by Dupont, but you may have to go directly to Dupont for purchase. Kapton's high Tg and melting point of over 400 C make it a very good material for high power planar and ribbon speakers. Kapton is also a good substrate for sputtering metals like Aluminum or copper. Many flexible PC boards use Kapton, as it is safe to solder to without special materials.
Kapton is a little "noisy" when you vibrate it.
There are a wider range of adhesives for Mylar/Kaladex than for Kapton.
mylar 1360 kg/m3
kapton 1535 kg/m3
Aluinum 2700 kg/m3
LineSource said:
Hi Linesource
I though I was the only one that felt like this about kapton
Kapton is heavy even as an under layer. Its fine in other drivers and formers but in a ribbon I would rather not have it, am I wrong?
An aluminium ribbon is cheaper and plentiful; people claim it’s the best for pizzicato and percussive sounds, don’t know if this claim can be verified in a meaningful way.
I personally don’t even like typical aluminium tweeters so maybe its my ears.
Does anybody know what film ATCO use in there military ribbon transducers, there so secretive and difficult to deal with am told.
I have a pair of prototypes and I am enjoying the detail and stage of sound before me, vastly superior over any dome or cone midrange I have heard in Europe,
even my ATC super domes sound like cotton in comparison, that would be darker and almost like the clothe grill is still on them.
I never though I would ever say that, but ever dog has its day I suppose, no disrespect intended Bill
Unfortunately, the higher the Tg, the "noisier" the material tends to be, with Kapton being downright crinkly. Best yet would be a material that's more amorphous, maybe with a Tg below room temp. For my 'stats, I use Clysar, which is quite nonresonant, but does suffer the disadvantage of needing regular heat-shrinking to maintain tension. It might be fun to try that material in a ribbon.
Even more interesting might be unaligned PVDF, but drawing it into freestanding films that are thin enough could be a challenge. A fun approach as a workaround would be to blend in a small proportion of a liquid crystal polymer (like Vectra), which would align in the direction of extrusion and form a molecular fiber reinforced composite.
Even more interesting might be unaligned PVDF, but drawing it into freestanding films that are thin enough could be a challenge. A fun approach as a workaround would be to blend in a small proportion of a liquid crystal polymer (like Vectra), which would align in the direction of extrusion and form a molecular fiber reinforced composite.
SY…any experience with using grape skins for speaker cones? Hemp, banana peels, and sea weed are now used. : -)
The real challenge is bonding a thin metal foil like aluminum to a thin plastic film like Kaladex or Kapton using a low weight attachment process that creates a strong, flexible, long lasting bond that will not separate from years of vibration from strong electromagnetic forces.
ANY IDEAS on how to attach a thin aluminum foil to a thin plastic film? Typical adhesives are heavy and stiff. Some type of thermal or solvent bonding seems necessary. ANY IDEAS?
Sputtering the metal to the film is the traditional method.
Sputtering a thin metal layer of a couple microns thickness onto a thin plastic film substrate of 5-8 microns can create a single conductor ribbon with modest resistance/length. The film/metal would be too thin and fragile to etch. To achieve horizontal rigidity without corrugation(pleating) requires an 8 micron or thicker film and hence low efficiency. High currents can cause metal migration on the thin metal layer, resulting in long term failure.
Sputtering an 8-20 micron thick metal layer onto a plastic film substrate allows etching of a serpentine conductor that is physically robust and long enough to have modest resistance/length, but is typically heavier than desired since a thick plastic film is needed to survive the long, often multi-pass, sputtering cycle.
The real challenge is bonding a thin metal foil like aluminum to a thin plastic film like Kaladex or Kapton using a low weight attachment process that creates a strong, flexible, long lasting bond that will not separate from years of vibration from strong electromagnetic forces.
ANY IDEAS on how to attach a thin aluminum foil to a thin plastic film? Typical adhesives are heavy and stiff. Some type of thermal or solvent bonding seems necessary. ANY IDEAS?
Sputtering the metal to the film is the traditional method.
Sputtering a thin metal layer of a couple microns thickness onto a thin plastic film substrate of 5-8 microns can create a single conductor ribbon with modest resistance/length. The film/metal would be too thin and fragile to etch. To achieve horizontal rigidity without corrugation(pleating) requires an 8 micron or thicker film and hence low efficiency. High currents can cause metal migration on the thin metal layer, resulting in long term failure.
Sputtering an 8-20 micron thick metal layer onto a plastic film substrate allows etching of a serpentine conductor that is physically robust and long enough to have modest resistance/length, but is typically heavier than desired since a thick plastic film is needed to survive the long, often multi-pass, sputtering cycle.
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