What is the ultimate PCB material? I have searched around
for companies which manufacture PCB prototypes for folks
such as us. But there are so many different high end materials.
Like teflon, getek, cynate ester, rogers, and duroid. I have
heard that teflon is great. And not so much because of the low
permativity but because of the consistency of permativity across
the audio frequency range. All comments welcome. I would
love to hear about anyone's experiences with these materials.

I am not an expert. However, I will give you my opinion on PCBs.

You did not mention EPOXY. Epoxy PCBs are the most common type of PCBs. Actually, there are 3 types. You can distinguish them by their colors...

Light Green = Glass epoxy PCB.
Beige = Paper epoxy PCB.
Brown = Bakelite epoxy PCB.

At Radio Shack, you can find the beige and brown epoxy protoboards. Nowdays, these inexpensive boards are made in China. On the other hand, Welborne Labs uses a high-quality, light-green PCB in some of their kits. These are very, very tough and nice. In my view as a DIYfer, these light-green, glass epoxy PCBs are the ultimate.

By far, the nicest looking PCB I've seen is the one inside the Audio Valve RKV headphone amp. It's a lovely red PCB that looks and feels very tough. I believe that this PCB is glass epoxy, but I'm not sure.

teflon but try to find it .

VERY expensive

I did not mention the normal materials.
Only the higher end stuff.
This site says it makes teflon boards
but I have no idea how much such a
board might cost without sending in
a request for quote...

http://www.protoengineering.com/index.htm

gariver, is this like the 'light-green, glass epoxy PCBs' you're refering to?

http://www.headphoneamp.co.kr/bbs/bb...9dd0e21ab62042

Yes...precisely! That's a glass epoxy PCB, and it's a good one! I like them because they are tough. I mean, they can take a lot of heat without getting damaged!

neat. so, just what is 'glass epoxy'? i mean it's not something quite as simple as fibreglass. what's in that stuff -- is it a mix or special process or just a type of pourable resin that's highly thermoresistant when it's set? is it something one could create with at home, like casting resin? i'm afraid i know nothing about it.

actually glass epoxy IS fiberglass with epoxy resin , kinda like the crap you use to work on a corvette body when it gets dinged but made into sheets and bonded to the copper plane

Listen, my knowledge of these materials is limited. I am not an expert by any means. Right now, I have second thoughts on my earlier posts. The brown bakelite is most likely just bakelite, not epoxy.

I do understand, however, why Teflon is used: Teflon can take plenty of heat! Why is this necessary? Solders are poor conductors of electricity compared to copper. They only provide 10 to 15% of copper's electrical conductivity. So for a high end PCB, you would prefer an eutectic solder that has better conductivity than regular solder. Now, to get the highest possible conductivity out of an eutectic solder, you need higher temperatures. That's why Teflon is preferred even though it is much more expensive than epoxy.

no.no,no man

It is not about the mechanics when we are talking about audio (or medical , where most audio innovations come from ) , but the electrical performance (sound for audio , errors in medical where mistakes can be lethal)

What is considered the ultimate dielectric for a capacitor ?

TEFLON ! (a vacuum?)
Next is (no cap discussions please) one of the plastics , polypropylene , mylar , etc. But teflon is the most nuetral , imposes less of its own sound than the others .

Bakelite falls far down the list as a dielectric for audio. But has seen use since the earliest days of electronics . Epoxy ? Many types , some good and some not as good .

With circuit boards we want strength , the ability to bond to the copper plane , heat resistance , and a good dielectric .

Fiberglass is only lacking if compared to the teflon or poly boards , great durability and heat resistance .

All things come down to price vs. performance in the real world . For our purposes any of the above are fine and in fact it would be silly to put a mediocre design on a teflon board and follow with teflon caps (maybe not for a gilmore design though )

First, a digression: you usually see fiberglass epoxy laminate called "FR4", since that's easer to type. "FR4" is a UL fire resistance code (thus "FR") so it could apply to other materials, but for PCBs it always means "fiberglass epoxy laminate". And, it refers to a particular grade, since there's also FR3 fiberglass epoxy laminate. FR3 grade isn't nearly as common, though.

Anyway....The thing with Teflon is that it has a higher dielectric constant and higher surface resistivity than FR4. Does this matter? Well remember, surface resistance and parasitic trace capacitance are a function of distance between the conductors. The point is, if you've got a densely-packed board, you may not have any choice but to use Teflon or Rogers 4000 or something high-end like that. But if your board isn't very dense, you can get the exact same effect as going with a high-end PCB substrate by simply moving your traces farther apart. Frequency also matters: if you're doing microwave work where every trace radiates in the gigahertz range and you've got a 6-layer board, putting some Teflon between the layers may be essential to success. For audio work? Well, put it this way: open up your favorite piece of audio equipment and tell me what kind of board it uses. Betcha it's FR4 or phenolic paper.

Quote:



it is? pray tell, how do they get it evenly translucent like the board i linked to? i can't see fibers. special glass cloth? a very flat spaced weave maybe? i'd like to get my hands on fibreglass that comes out like that.

have you ever used automotive fiberglass ? Looks just like that after the resin is applied and sanded .

ONLY TEFLON MATE!

Try Rogers Corporation, I got sample from them

Mark Levinson uses cyanate ester and arlon 25n for
their upper end products (No 380s and 32 respectively).
Ayre uses some "special high-speed circuit board material"
(direct quote) in their upper end products. And those are
just two I found right away. So there are manufacturers
using high end pcb materials. What do they know? I
have also read somewhere that the permativity of any
material is also a function of frequency. Not a strong one
but still there. So a material with significant deviation of
it's permativity in the audio frequency band might introduce
some kind of nonlinear distortion. And that atleast teflon
has very little deviation. I don't know if this is true or not.