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To attain dome shaped deposit?

I am using electroforming to produce a letter; but of course its edges are lifted. How can I unlift edges of my little plated letters. I want them to be even a little oval shaped like a dome. Can I use a shield in order to obtain this feature?

Özüm Safaoðlu
arge engineer - Turkey
2007

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2007

Ozum, when you said on letter 45532 that nobody in your company had electroforming experience, I suggested that it is possible to retain an electroforming consultant, but you didn't want to do that. I named a local distributor of plating processes and suggested you invite them in to take a quick look, but you don't want to do that. I suggested that you contact some vendors of stress testing equipment so you could understand how stress ties in to the lifting issue, but you don't want to do that...

I understand your reluctance, but unfortunately readers who haven't seen your situation can't help when we do not even have an agreed-upon vocabulary here from which to proceed! When you say "lifting" I know what that means to some electroformers (tensile stresses pulling the edges of the letters up), but I suspect that to you it means thicker plating at edges. Yes, shields (plastic 'stencils') can help that problem by lengthening the distance that the current must travel to reach the edges. It may be that a thicker photoresist (thicker than the letters you are trying to electroform) may serve as a shield and be the answer. But please try to contact a local rep from any plating equipment supply company or any plating chemical company and have someone with experience lay eyes on what you are trying to describe because I don't understand what you are trying to describe. Good luck.

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

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2007

I have set a sulphamate bath with a few nickel chloride content. I added saccharin too. My stress was compressive instead of tensile. I increased the nickel chloride content ; now I am a stress which is nearly zero. And I use a zero stress temperature and current density combination. I know I am really new at this area as a student who is even at the beginning of his microelectronic journey- if I mention that I am on my 18th age , that would be easier to understand the conditions. I am in a hard economic situation , so I am trying my best with things I have in order to keep my educational preferences in the smoothest way with my engineer father. He's not been in this issue before ,so if you think I AM THE one that can possibly run a project like this considering my scientific fundamentals which are probably much worse than all other people here. If you consider my attributes I think that is possible to see that I cannot access everything. So I have to succeed with your advice and the limited information on the internet. But Mr.Mooney it is even impossible to contact you without this site. I still cannot see why it is a bad thing to learn from you.

Now I give in trying to reach you in other ways. Okay . I am just gonna try to take some answers here even though it will be the end of my project with a failure because the post are sent a day later after I write it in finishing.com. Here is it all about :

I was applying the process in Watts solution before. But because I found out my stress was too tensile I somehow ordered a little sulphamate to try it in a little junior bath, because I cannot dare to buy too much. I tried without any additives. Of course in pantomime of wetting agent I had a surface with pits. Then I added saccharin to reduce my tensile stress and to attain a bright surface. It was really bright.But I still got the pits. Then I added commercial wetting agent . Pits were gone .
My edges were not lifted before I added saccharin ; maybe I dragged my stress excessively towards compressive . But compressive does not lift edges based on my limited current knowledge.
Then I have cut a little rectangle to try if shield would work to pull my edges down. It was working. Can you imagine how much it was meaning to me ? Because I can't have access to what you are talking about. Anyway, now I can attain a full bright surface with pulled down edges with polyethylene or polycarbonate shields. But like I mentioned before, when I look the patterns of another company I see that the edges of letters are even coming with radius. How can that be possible?
I am giving two possibility :

1-My stress is still now stable in a good condition thus edges are lifting.If pull the stress down I still have a little lifting because of the distribution of the current density , but then if I use shield I can attain edges with radius.
2-My stress is Okay , But I am having trouble with only the current distribution so if I produce a nice working shield with making my film drawings smaller with autocad and aligning the shield with my mandrel adequately I can then take radius edges.

Mr.Mooney ,I am sorry if I looked different than I am , but yes I am having monetary support from the company I told you about before , and yes my father is with me on this subject who is even less compatible than me at this subject. But I cannot access all those things you are telling me . These are my opportunities . This is your decision to help me . If you still insist on being a tail with some money which I don't have, after some consultants , I will be still respectful to you and this wonderful site of yours. I am glad for all the help I get from you. Thank you....

Ozum Safaoglu
- Turkey

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Compressive stresses cause that face of the electroform to try to expand, which forces the edges to bend away; tensile stresses cause the edges to bend towards them. Look at your hand with your fingers slightly bent; tensile pulls on the palm side of your hand do that. Yes, saccharin reduces tensile stress or causes compressive stress. But I don't know if the finished side of your parts is facing the mandrel (which is the usual case) or facing the solution (which is the case for bellows and some other intricate parts). Nor do I know whether your competitor's parts are done the same way or upside down from yours. Just as you haven't seen other electroforming installations, nobody has seen yours.

You want immediate real-time help rather than delays between postings, but the way to solve that problem starts by asking a supplier to drop in as we suggested. Sorry but we receive more than a hundred requests for help every day and I cannot provide real-time help to a hundred people a day.

I wish you great success in school, in your career, and in helping your father with this product line, Ozum, but you ask how to obtain a smooth radius and I don't even understand what you mean. I don't know what your letters look like and where this radius would be. Sorry but I just don't even understand what you are asking in most of your questions! Sorry!

Yes, wetting agents can be effective in eliminating pits; that is the basic reason for their use (keeping pit-forming hydrogen bubbles from sticking).

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2007