Lowest Resistance Aluminum Finish

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Discussion Overview

The discussion revolves around the various finishes available for aluminum standoffs, specifically focusing on which finishes provide the lowest electrical resistance while also offering protection against corrosion. Participants explore common finishes such as anodized and iridite, and their implications for conductivity and durability.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants suggest that using a separate ground strap may be more effective than relying on grounding through standoffs.
  • One participant notes that anodized finishes are generally high resistance, and without anodizing, aluminum oxide forms, which is also insulating.
  • A participant proposes sanding off the coating at the ends of the standoffs to create a better conducting path, while also mentioning potential issues with corrosion if aluminum contacts copper in the presence of moisture.
  • Another participant discusses the tradeoff between hard protective coatings, which tend to be non-conductive, and conductive coatings, which may lack durability. They mention Alodining as a conductive finish that provides some corrosion protection but express uncertainty about its longevity in corrosive environments.

Areas of Agreement / Disagreement

Participants express differing views on the effectiveness and implications of various aluminum finishes, indicating that multiple competing perspectives remain without a clear consensus on the best approach.

Contextual Notes

Participants highlight limitations related to the durability of finishes in corrosive environments and the insulating properties of aluminum oxide, but do not resolve these issues.

j777
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Hello,

When purchasing aluminum standoffs you can get them with many different finishes. Which finishes have the lowest resistance and offer protection against corrosion?

The following link lists finishes available from a popular electronics hardware manufacturer.
 
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If you are that concerned about low resistance I would recommend using a separate ground strap instead or relying on grounding through stand-offs.
 
I'm not necessarily "that" concerned I'm just looking for advice on common finishes like iridite, anodized, etc...
 
Not really an expert but anodise is pretty high resistance, but without anodise you are going to form Al oxide which is also insulating.
Since the post only contacts the board at the top and the case at the bottom, you could just sand off the coating at the ends to make a good conducting path. Depending on how well the coating has been applied the screws will probably strip it out of the threads you are using tapped standoffs.

The main concern with no coating (or only a thin one ) would be that if the Al is in contact with copper on the circuit board and any moisture gets in you will have a corrosion cell.
 
Last edited:
You have a tradeoff because the really hard protective coatings are non-conductive, and the conductive coatings are not so durable. Alodining is a conductive finish that offers some protection. Don't know how long it will hold up in a really corrosive environment.
 

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