What's good about teflon board and 2 oz copper board?

I have a phono kit that uses teflon board? Besides it is flexible and as alleged, it can absorb vibration, what's good about teflon board?

The kit supplier recently debut a new teflon board with 2 oz copper (and a little bit rearrangement of traces) and I bought one. After moving all the parts to the new board and the usual tuning, I must say the performance is extraordinary good. The highs and lows are extended while the highs are silky smooth. I must say the new teflon board with 2 oz copper brings the performance to another high.

What is 2 oz copper board? What does the usual circuit board use?
 

jean-paul

Ex-Moderator
2002-09-20 7:20 am
Germany
Hi, AFAIK "2 oz" means that the copper tracks are double the thickness of normal material. Since I don't even bother to understand non-metrical stuff : in Europe we call it 35 micrometer versus 70 micrometer for the extra thick material. I never noticed much difference with small signal applications but I would prefer thicker pads and tracks with power supplies and power amps. When tinned the tracks will be around 100 micrometer which will be able to carry pretty much current.

I would rather prefer it if the manufacturers would focus more on the quality of the material. Nowadays only touching the tracks/pads with a soldering tool is enough for peeling off the tracks/pads, be it normal or extra thick material.

Teflon has better electrical properties and is superior to epoxy. It is very good material for RF circuits but it is expensive and more difficult to machine/cut. I don't have experience with a direct A-B comparison with the same circuits but since it is better electrically I suppose it will measure/sound better too. Teflon is much more heat resistant but when overheated it will give a hazardous gas. You can google yourself for the properties of Teflon.
 
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Thank you for your input. I just don't know why changing to a 2 oz circuit board could make such a difference bearing in mind this is a very low signal phono preamp.

Talking about quality of copper on circuit board, how do I know what kind of quality is being used by manufacturer? If I want to make circuit board, is there any grade (other than 2 oz copper) of material that I can specify?
 
the thickness of the traces don't matter provided the resistive voltage drop is negligible. I'm confident the re-arrangement of the traces is the only reason it sounded different.

they make half ounce board as well as 1, 2,4,6,8, and 10 ounce board.
as far as the quality, you aren't going to find low oxygen copper circuit board, its just generic 99% IACS copper.
 
There are two things to consider in the trace - the width and the thickness.
Using "2oz." traces that are super thin buys you not much compared to a double width trace of 1oz. Although there may be some difference at UHF and up due to the shape factor...

I prefer fatter traces for audio, and don't understand why some folks design audio boards with the same super narrow width traces common to data designs.

The heavier copper also is better for soldering since it sinks more heat and doesn't pull off the PCB quite as much when heated a bit too much...

So I vote for wide and fat traces for audio.

The "teflon" board is best at very high freqs. The board is a dielectric, just as it is in a capacitor. Especially if there is a ground plane. But regardless. Teflon caps are on top of the list for capacitor performance.

It's difficult to say why or if an identical layout would sound better made from one material or the other. One would have to try and test it. Needless to say it is unlikely to hurt.

Oh, the flexibility may very well effect any microphonic effects... audible? Dunno.

_-_-bear
 
the quality of the copper makes no difference, but that's a debate for another day.
I don't know of anyone selling 5n or 6n copper pcb boards. unless you want that copper on a 99.99% alumina substrate, shipped to you in a container purged with argon..... which would come out to triple digit $/square foot.
 
On boards that have plated through-holes, the boards are etched, then drilled, then copper is deposited via electroplating. I think that the copper will not be especially high purity, and you won't be able to specify what purity you want; it will be limited by the process. The resulting trace thickness (initial copper thickness + plating) is described either by thickness in micrometers or in "oz" which is the weight of copper (in ounces) per square foot of area. Someone already mentioned that "1 oz" is equal to "35 um" (micrometer).
 

wakibaki

Banned
2008-01-08 11:51 pm
Since most equipment is built down to a price FR4 is much more common than Teflon (PTFE) as a substrate, Teflon being considerably more expensive. Depending on the application, FR4 starts to get problematic above ~2.4 GHz, this is because the permeability is less well controlled than that of Teflon. This makes no difference at baseband (audio) frequencies, but has increasing significance with frequency in designs using distributed components.

Of more interest are the commonly available finishes which are applied to the copper. These are I.S, (Immersion Silver), HASL (Hot Air Solder Levelling) (lead free now) and Au/Ni (gold over nickel) or Au/Pd/Ni which has an intermediate palladium layer, the Ni and Pd are normally electroless deposition, with the gold being immersion.

None of these, however, make any real difference in audio applications, unless you were thinking of using an edge connector. If you're interested in this stuff, you'll learn more from google than asking here.

w
 
This link is to an excellent toolkit that will provide info on current carrying capacity for PCB traces at various copper widths.
PCB Via Current | PCB Trace Width | Differential Pair Calculator | PCB Impedance

IPC-4562-a is the specification for copper foils used on PCB's, this replaces the IPC-MF-150 spec.
Basicly PCB foils fall into 2 main categories:
Rolled Annealed Copper Foil ~ 99.9% pure
Electrolytic Copper Foil ~ 99.5% - 99.8% pure
The main difference between the foils is the grain structure and physical properties.
The copper purity or grain structure of the PCB's has never been an influencing factor when circuits boards are designed,
the dialectric has only been of a concern for realy high frequency design, high giga hertz, same as skin depth etc.
Interestingly for the purveyors of micro-diodes between crystals and having directional copper for signals, then electrolytic
copper foil shouldn't work!
Anyway the attached PDF has more info:
 

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Further to FR4, there are numerous differnt flavours of prepregs etc of FR4, varying weaves of the cloth (106, 1080,2113,2116,1652,7628 to name a few), different Tg ratings etc etc.
Teflon is very rarely used except in RF design or in very harsh conditions! FR4 covers a wide range of substrates.
As to audio differences between PCB's, only if the design is so abysmil that it affects the signal integrity!
 
Marce,

If you go build urself a nice F5 amplifier... simple enough... you will find out quickly that you can change the selection of parts and this will alter the "sound" that you hear somewhat dramatically in many instances. For example change just one set of power resistors, nothing else.

Of course what you are listening through is not up to the task, then these things make no real difference at all...

Now, if a PCB material will have any audible effect is certainly not clear. However in the case of the commercial preamplifiers made by Spectral on some models great care was taken in the selection (and layout) and material of the boards. They didn't do this merely for fun, or to add cost, or for "bragging rights".

Otoh, and imo, foil thickness and width do somehow have an effect, albiet unclear in all regards... and again if your system and ears are not going to hear it, then they won't and there is nothing to think about or be concerned with...
:D

_-_-bear
 
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Components can change the sound.
Layout is critical in any PCB.
But changing from say FR4 with 7628 pr-prg to 1080 pre-preg to Teflon aint gonna change things at audio frequencies, and if they do it will be measurable, quite easily as distortian to the waveform.
Doubt Spectral have used anything exotic, or any different PCB base materials than the rest of us in PCB world do, there just arn't that many material manufacturers left.
Even the nice F5 layouts the distance the signal travels and the topography of the boards means there is little chance of the signal being corrupted from one point to the next is non-existant.
Sorry, we are gonna have to disagree on this point, but signal integrity and PCB design are a well researched subject, and at the low audio frequencies parsitic effect are minimal.
 
Hi,
I am curious as to what exotic materials they have used, that aren't being used for just marketing blurb reasons.
As at audio frequencies very few (if any) PCB parasitics are going to influence the wave length from one component to the next. The tolerance and component parasitics will cause more deviations.
Dielectric losses, relative permittivity, loss tangents, skin effects do not affect signal quality until you get into higher frequencies (GHz), and any effects are measurable.
 
I am sure you are curious - they made almost no mention of it in their advertising, afaik.

I think it was actually a polystyrene material since it seemed to melt with excess soldering iron heat, iirc. It was said that it was teflon, dunno. Maybe in the DMC 20 or the one before that. Going back into audio history now... iirc the person who did the PCB layout and design had worked for Tektronix doing that work for them...

You should stop thinking about measurable effects so much, imo.
Try to find a difference between a Caddock and Vishay resistor of similar design and power rating, then put it in a circuit and listen. etc... as always YMMV. ;D

If your curiousity is overwhelming, PM me...

_-_-bear