PCB Corrosion Gold- Aluminum

[ManuelGG]

Hello,
I have a enquire, We are designing a PCB and we are not sure what is the better finish for it.
In the external sides of the PCB I have to areas in which I am going to fix to aluminum parts. The usual termination for the PCB is Nickel+ external gold plated surface. Like gold and aluminum are dissimilar metals, We are thinking on require this areas without gold (only nickel) What do you think?. I think it would be interesting to considered the following cases:
PCB termination:
- ENIG (Nickel+ gold)
- Nickel (without gold)
Protection:
- Nothing
-Conformal coating
Part in contact with PCB:
-Aluminum without treatment
-Anodized aluminum
-Aluminum with a conversion treatment (Iridite, Alodine)
The screws used to fix the aluminum part to the PCB will be stainless steel screw (is it necessary to isolate the head of the screw from the PCB? Fixation scheme: screw-PCB-aluminum part

 

[cloa]

Why are you talking about corrosion no enironment mentioned anyway it would be better to posted in the electronics forum.

 

[ScottyUK]

Possibly better here if this is some unusual application exposed to a particularly aggressive environment. Normally we just keep electronics as clean and dry as possible.

As cloa says, how can anyone help you if we have no idea what the environmental conditions are? Post sufficient information to allow us to help - we aren't mind-readers.


----------------------------------

If we learn from our mistakes I'm getting a great education!

 

[ManuelGG]

Hello,
Tank you for your responses. The environemt for the PCB´s I am talking about is inside of a electronic rack, that could be in a building ( not outside exposition). This rack is not sealed from the ambient.
Regards

 

[cloa]

What is the ambient conditions?