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Coating 1mm thick copper on copper base metal

October 12, 2010

Is that possible? I need to plate/coat a small recessed rectangular area (3mm x 3mm) in the PCB to make it level with the PCB's surface. It's a thermal junction for an LED heat sink.
My preferred technique is sulphate. All of my first attempts ended up with no cohesion at all. I use CuSo4 + NaCl + distilled water. I ran the current using old Nokia phone charger.

Many thanks in advance

Clemence Ronald
Hobbyist - Indonesia

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October 12, 2010

Hi, Clemence. What you wish to do is not impossible, but it may be impractical, and it can probably only be done by an experienced technician with R&D laboratory-quality equipment. One issue is the fact that electroplating "wants" to do the opposite of the leveling you seek -- it wants to grow a high spot and concentrate the plating buildup there. Another issue is that a thickness of 1mm, while certainly not unprecedented, is awfully thick for a hobbyist. A third issue is that chlorides are very powerful stress inducers, and probably incompatible with plating of that thickness. What are you doing to prepare the copper base metal that the plating is not adhering to -- the plating must deposit onto raw active copper, not a copper tarnish or oxide.

Good luck.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

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October 14, 2010

Finally I've succeeded to plate the copper using simple Nokia charger, CuSO4, distilled water, H2SO4, and some sugar. You were right Sir, the cleaning process is very important. I cleaned the specimen using sandpaper, NaOH, and finally soaked it for 5 minutes in H2SO4 before the immersion. The plating is thick enough with fairly good cohesion, nearly 1 mm thick! But after reaching certain thickness it started to develop coarse granules. I should find a brightener agent

The picture: The copper tube was only 0.5 mm thick

I'm thinking to "cold weld" the LED thermal pad directly to copper heatsink using electroplating. Is that possible?

Clemence Ronald
- Indonesia