I routinely use gold plating for our microwave circuit metalization.
In order to avoid any plating sliding under the photoresist and
shorting out lines that are tightly spaced, we evaporate a
Ti/Au/Ti seed layer, perform the lithography and selectively
etch the top Ti layer only on the locations to be plated.  After
plating just remove the seed layer as usual.   We have been
able to achieve good results with this process (even for lines 3
microns thick with a separation of 8 microns).

Good luck,

Sergio

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       ._,
     ,_| |._/\              Sergio Palma Pacheco
     |       |o/^^~-._      Radiation Laboratory
   /-'                | ~   3121 EECS Building
   \__/|_            /'     University of Michigan
         \__        | .      Ann Arbor, MI 48109
           |     __/'
           >   /'               Tel: (734) 936-2975
         /'   /'            Fax: (734) 747-2106
         ~~^\/'              e-mail: [email protected]

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>>-----Original Message-----
>>From: Jong In Song [mailto:[email protected]]
>>Sent: Tuesday, November 03, 1998 2:42 AM
>>To: [email protected]
>>Subject: Gold plating
>>
>>
>>Hello !
>>
>>I have some problem with my patterned gold electro-plating
>>with Sodium Gold
>>Sulphate solution.  The pH of the solution is around 8 and I
>>found out that
>>it etches photoresists (Shipley positive PR's such as 6812, 1512, etc)
>>slightly.  I evaporated Ti/Au (100/500 Angstrom) as a base
>>metallization on
>>a semi-insulating GaAs and made a pattern with photoresist
>>(~4~6 um thick) .
>>My problem here is that the patterns spaced closely (~ 10 microns) are
>>shorted (bridged) when the plated gold gets thicker that ~
>>1.0 microns.  It
>>may sound very strange since the photoresist pattern is as
>>thick as ~ 5~6
>>microns.  Although the solutions etches the PR slightly, the
>>PR patterns are
>>still there).  However, it is happening here.  Did anyone
>>have the same
>>problem and found a solution to this problem ?
>>
>>For your reference, I used a 10gr/liter solution at
>>2~3mA/cm^2 which gives
>>me the plating speed of   ~0.1microns/min.
>>
>>Best wishes,
>>Jong-In Song
>>
>>Associate Professor
>>Dept. of Information and Communications
>>Kwangju Institute of Science and Technology (K-JIST)
>>572 Sangam-dong Kwangsan-ku
>>Kwangju, Korea 506-712
>>tel) +82-62-970-2208
>>fax) +82-62-970-2204
>>
>>
>>