PCB boards, gold traces in middle layers

[Shark]

I still have a few of those put away. I use a few at times for cementing waste solutions.

 

[olson13]

I'm still confused, I can't imagine that there is gold between the two surfaces, on the inside of the board. OP I think you need to cut one to confirm.

The only time I've ever seen gold anywhere other than on the surface is with fully plated vias and through-holes, and that's pretty rare. Even then it's still on the "outside" and can be recovered with Copper Chloride etching.

It's gold through the board. I confirmed with the board room at my job. They design these boards.

 

[haveagojoe]

It's gold through the board. I confirmed with the board room at my job. They design these boards.

Yes but how? Photos would help, even if you think it's difficult to see we can recognize it.

 

[haveagojoe]

Basically there are 5 possibilities of how gold can be "through" the board:

1. ENIG with open vias - use normal Copper Chloride etching
2. ENIG with gold below the solder mask, tented vias - remove solder mask with lye and then use normal Copper Chloride etching
3. ENIG with solder mask and epoxy-plugged and tented or capped vias - remove solder mask and use normal Copper Chloride etching, forget about the tiny amount of gold in the vias
4. ENIG with gold-filled vias (I have never seen these) - Use normal Copper Chloride etching and then pop the via fillings out with a punch
5. Multilayer board where the internal layers are also ENIG (I have never seen these) - possibly shred if you think it's worth it, then normal Copper Chloride etching.

I don't think there is any possiblity that the traces themselves are the full thickness of the board from one side to the other. That would be impossible to manufacture and would require a ridiculous amount of gold which would not be justifiable in any product.

 

[4metals]

Yes but how? Photos would help, even if you think it's difficult to see we can recognize it.

If it is internal to the boards all of the drawings in the world will not allow the chemistry to reach the internal spaces without mechanical destruction to expose it. So all of the explanations of how it is applied are moot without the application of a big hammer. (or hopefully a more efficient way of exposing the gold)

 

[haveagojoe]

If it is internal to the boards all of the drawings in the world will not allow the chemistry to reach the internal spaces without mechanical destruction to expose it. So all of the explanations of how it is applied are moot without the application of a big hammer. (or hopefully a more efficient way of exposing the gold)

I think most likely these are just ENIG with open vias, and OP has interpreted "through the board" to mean there is gold inside somewhere, which I have never seen and I don't really believe exists. It's possible in theory with a multilayer board but OP says they are not multilayer. Also I don't think there would be much point in having gold internally as those layers are not subject to oxidation.

 

[Yggdrasil]

If it is internal to the boards all of the drawings in the world will not allow the chemistry to reach the internal spaces without mechanical destruction to expose it. So all of the explanations of how it is applied are moot without the application of a big hammer. (or hopefully a more efficient way of exposing the gold)

Yes true, but according to the OP the boards are produced in house and single layer, double sided with through vias with Gold.
And since he has been talking directly to the designers I'm inclined to believe his description.

This is a situation where direct leaching would suffice and no crushing should be necessary.
Pictures would be nice but the description is relatively clear.

 

[haveagojoe]

Yes true, but according to the OP the boards are produced in house and single layer, double sided with through vias with Gold.
And since he has been talking directly to the designers I'm inclined to believe his description.

This is a situation where direct leaching would suffice and no crushing should be necessary.
Pictures would be nice but the description is relatively clear.

OP didn't mention vias, that's what I'm trying to clarify- whether or not he believes there is gold in some internal layer which cannot be accessed. If it's just in the vias it can be easily got by Copper Chloride etching, unless they are epoxy-filled in which case I'd say it's not worth the effort of going after such a small amount.

 

[Yggdrasil]

OP didn't mention vias, that's what I'm trying to clarify- whether or not he believes there is gold in some internal layer which cannot be accessed. If it's just in the vias it can be easily got by Copper Chloride etching, unless they are epoxy-filled in which case I'd say it's not worth the effort of going after such a small amount.

Here is what he said:

They come from my job. I work on automated welding machines. I asked the guy who designs our PCB boards, and he did confirm that gold goes through the board. Some of these boards are having high frequency/temps/current going through. So, I believe that is why the boards were designed and made this way.

And then:

Sorry for the not so good description. It is a single layer boards. But, the traces run in both sides of the board and they follow all the way through the depth of the board. If I could get a good pic I would send it. But, it is so hard to see. I confirmed with the guy in our board room and the gold traces do run through the board. All be it very thin traces.

As far as I'm concerned, I can't come up with another way of interpret it.