Gold coating ceramics

[tapley]

I am trying to find vendors that can selectively coat ceramics, such as alumina for a laser cavity application. The shape of the part would be consider probably low to medium in the level of complexity, but I am worried this can only be done with evaparotive techniques which may cause non-uniform thickness and shadowing. Anyone have experieence with this?

 

[sreid]

I would think that you could electroless Nickel plate followed by standard Gold plating. This is the process for gold contacts on Printed circuit boards.

 

[EdStainless]

Don't rule out vapor methods. If they are done at reduced pressure (at least partial vacuum) then they might avoid the problems.
There are numerous metallizing methods. You may need to find people with semiconductor experience.

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http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[unclesyd]

You might want to give these people a call. I've seen this process, Laser Gold, mentioned in sveral articles.

http://www.epner.com/laser_intro.ssi

 

[unclesyd]

Here is an electroless gold for use with ceramic substrates.

http://www.uyemura.com/malaysia.htm#1

 

[CeramicMetal]

There are a few ways to do this.
Selective plating of a non conducting material is usually not kept to tight tolerance (dimensionally). The coating thickness is controlled relatively well. A flash of electroless nickel in the 25-50 microinch range and flash of gold in the 25-75 microinch range should suffice. Pretreatment of the ceramic is the key to adhesion. A thicker coating of gold ussually becomes less reflective (patchy). Remember that the electoless process is "all over" the ceramic. Even with masking selected areas the bath will penetrate the mask.
Previuosly mentioned evaporated coatings are line of sight and expensive. If the cavity is enclosed such a tube type, PVD/CVD will not work.
Another possibility is ceramic metallization. A thick film ink can be fired on the ceramic creating a conductive hermetic surface that can be plated with whatever you like.
If you send me a drawing I would be glad to investigate all the options and provide a solution.