IPC standards question

Ninja said:

Ummm...last I checked, gold and copper are two different metals... Have you confirmed what the deposit actually is?
SEM/EDS
WDS
heating for oxidation
wet chemistry/dissolution
any of these or other tests to confirm the actual chemistry of the deposit?

Click to expand...

We don't have such equipment in-house. Will try other means though.

Ninja said:

Ummm...last I checked, gold and copper are two different metals... Have you confirmed what the deposit actually is?
SEM/EDS
WDS
heating for oxidation
wet chemistry/dissolution
any of these or other tests to confirm the actual chemistry of the deposit?

Click to expand...

Put the deposit under XRF and saw high Au.

Is this only happening in one location or is it throughout the board after SMT?

Now to determine where the gold was prior to that process...
- In the circuitry?
- Plated/Flashed on the pads?
- In the flux (doubtful)?

Once you know where it started and where it ended up, you can hypothesize and test for mechanisms from there to here.

EDX Results.

The EDX results appear to be that of soldermask, barium being a key indicator. The deposit is under the soldermask. It could also be discolored/alternate color soldermask although this seems less likely.

outdoorsNW said:

The EDX results appear to be that of soldermask, barium being a key indicator. The deposit is under the soldermask. It could also be discolored/alternate color soldermask although this seems less likely.

Click to expand...

Apologize for not updating here, we did a small batch run of the same board a while ago, the gold deposits appeared after reflow. To our surprise the deposits can be clean off just using cotton bud to scrub immediately. This means the deposits is not under soldermask as I claimed before.

blackholequasar said:

Is this only happening in one location or is it throughout the board after SMT?

Click to expand...

Only this particular pins.

Ninja said:

Now to determine where the gold was prior to that process...
- In the circuitry?
- Plated/Flashed on the pads?
- In the flux (doubtful)?

Once you know where it started and where it ended up, you can hypothesize and test for mechanisms from there to here.

Click to expand...

It's the color appears to be gold but from the EDX results no gold present.

Is it flux residue?