Letter 32089

Electroforming foil to a stepdown/recess [Ontario] 

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I am working in eforming of foils for smt. I am looking on how to achieve different thickness on the same foil. What to passivate and activate the nickel with?

Jane Munro
plating - Mississauga, Ontario, Canada

Passivation of the nickel can be achieved by dipping it in strong solutions of sodium metabisulphite, sodium dichromate or potassium permanganate. Activation depends on what type of nickel you are using. If it contains any additives, you will almost cetainly need to use a nickel strike. Changing the thickness can be done with screens or robbers.

Trevor Crichton R&D practical scientist - UK

For manufacturing two step SMD Stencis you will need a two step lithographie, that means first lithographie on your mandrel, then nickel deposition, then the second lithographie covering the area where you want to have the thinner regions. Activating the nickel is not easy, as a nickel strike will damage the resist from lithographie. What you can use if you have an brightener in your plating electrolyte is a mixture of iodine, iodid and sulfuric acid.

Good luck,

Marcus Hahn
- Lucerne, Switzerland

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