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ENIG used with stainless-steel membrane switch

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#55670

ENIG used with stainless-steel membrane switch | 24 July, 2008

We have a new board that requires a membrane switch. The membrane switch is a 1" stainless-steel dome. We were wondering if ENIG plating will hold for an expected life < 1000,000 for the switch. Any experience using ENIG with this kind of dome/switches will help. Regards, Rafael

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#55671

ENIG used with stainless-steel membrane switch | 24 July, 2008

I seriously doubt it. It is extremely thin and the gold's only real purpose in life is protect the nickel underneath from oxidizing. Once you wear that very thin gold off you will have exposed, oxidized, nickel and loss of conductivity.

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#55672

ENIG used with stainless-steel membrane switch | 24 July, 2008

I would agree with Doug, Enig with this type of switch is doubtful that it will hold up. You may have to think about Electroplated Deep Gold (hard Gold) 30-40 micro inches.

Regards, Mike

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#55680

ENIG used with stainless-steel membrane switch | 24 July, 2008

As part of the IPC-4552 specification testing, they ran ENIG at 2 uinches for 1.5 million cycles for a membrane-type keypad application [there was no testing for the wiping-type switches]. They stopped testing when the membrane began breaking down. There was no damage to the ENIG surface. Their data can be found in the technical paper that is included in the appendix of IPC-4552

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#55681

ENIG used with stainless-steel membrane switch | 24 July, 2008

At the 2004 IMAPS Nordic Conference, Claus W�rtz Nielsson from Nokia Mobile Phones published "The Evolution of Surface Finishes in Mobile Phone Applications" [www.imaps.org/adv_micro/papers/Nordic2004paper.pdf]. Some of the results were: * Corrosion problems with ENIG coated key pads. * A new formulation of the ENIG process (higher P content and less porous Au coating) improved the corrosion stability. Nevertheless, he concluded, "It becomes more and more clear that the thin ENIG in the future not will be able to address the need for higher wear resistance in the extreme part of the product segments as gaming devices and phones used by workmen or during sporting activities."

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