Was I dreaming (fast PCB etching)

[(*steve*)]

I'm not sure I was dreaming or if I read it...

Did someone post or provide a link to a method they used to etch PCBs quickly?

It involved electroplating the copper off the board then finishing the process in conventional chemistry.

Or did I just dream it?

 

[hevans1944]

One manufacturer I used a long time ago electroplated first copper and then lead-tin solder through a photolithographic mask to define the traces and make plated-through holes. Board was originally clad with very thin copper on both sides and then drilled. They used electroless copper deposition in the holes to provide a substrate for subsequent plating, which may have involved plating on more copper atop the electroless copper before plating the holes with solder. They then chemically removed the mask and etched away all the copper that was not protected by the solder plating. End result was a 2 oz. copper board with solder plated on top of all the traces and in the plated-through holes. You could order thicker copper plating.

I thought that using the solder plating as an etchant resist was clever. These particular boards had gold-over-nickel plating on edge finger contacts, so I presume they had to mechanically mask those contacts after building up the copper layer by electroplating copper but before solder-plating the rest of the board. Sounds messy. I remember the finger contacts had an electroplating strip (sheared off later) that was used to apply the nickel base to the 2 oz. copper fingers and, later, the gold flash on top of the nickel. Not much gold, IIRC, only about 300 microinches. But that was a heck of lot thicker than I could do with an brush-type electroplating kit, and I couldn't make plated-through holes.

 

[Chemelec]

I have used this Method Many Times for many years:
It is Not particularly Faster, But Cheaper than Etchant with chemicals.
But also needs Final Completion with chemicals.

http://chemelec.com/Projects/Etching/Etching.htm