ENIG processed PCB pads with black contamination?

I assembled a couple of boards last weekend and found the immersion gold vaporizing from the pads leaving a black film. I was able to scrap the black, oxide contam?, off the pads with great difficulty. What is this stuff anyway and is there a more efficient way to remove the black material from the pads when I come across it on a board?

Sounds like a manufacturing issue. Did you contact the company that made the board?

I agree and I have contacted the PCB designer who contracted the fab house. I was looking for some way to process the PCB's since time is a sensitive factor with this project. I can't wait for new boards. This was a prototype batch and I'm assuming it was manufacturered in as short of a process time as possible.

I find it hard to believe gold was just vaporizing. It would have to be really really hot for that to happen, and a lot of other bad stuff would happen first. What happened on your end to cause the transformation from something gold-looking to black-looking? Was there a lot of heat applied, did it happen over time, something else? Did this happen everywhere this supposed gold layer was, or only in some places?

Are you really sure about the board house? Is it possible you didn't really get a gold coating? A picture would be interesting.

You might try acetone to remove it, or a product from chemtronics like electro-wash.

http://www.chemtronics.com/products/americas/e/cleaner_degreasers.asp

Agree, I'd ask for my money back if they claim the boards are gold plated and still doing this.

Here is a picture of a pad that shows the contaminated area.

Is that on top of the gold layer or what was left after the gold was removed?

Again, what exactly happened to the board to cause this transformation?

This is how it looks out of the packaging. Before anything has been done. Also, this is how some pads will look after applying a soldering iron to them. I have found that rubbing the pads, that have this black contamination on them, eventually removes the black material.

If this is how the board looks straight from the board house, then that's just wrong. Return the boards to the board house and have them do it right or get your money back.

This now sounds very different from "gold vaporizing". It's probably either bad plating or a layer of crud on top of the gold. What do you get when you remove the black stuff? Is the gold layer underneath?

While these questions are for curiosity, either way these boards aren't acceptable and you should deal with the board house to get it resolved.

Unfortunately, I'm not able to return the boards. I have to finish assembling the boards and ship by Monday. These boards are prototypes, the production run I'm sure is done by another pcb manufacturer.

The gold vaporizing. Your right earlier, one of my solder stations was set too high. This was adjusted to the correct temp. From what I can tell, there is only copper under the black contamination.

As far as the manufacturer. The designer I've been working with should be getting with that manufacturer with my feedback.

Looks like the flux or formal coating got hot. Did you find out what was going on?

Agreed...Out of all ENIG I have seen, if I see something like that, I would send it back. They have to have an error in their process..

Who was the PCB house you used? I want to make sure not to use these guys.