The authoritative public forum
  for Metal Finishing since 1989
-----

Problem in electroforming CD-DVD molds

adv.  

I'm working in the CD-MANUFACTURING, and I'm running mastering and galvanics systems in Belgium. And my question is what I can do about dents when I'm growing a mother from a direct father. We are mastering with the AM 200. And when I want to grow a family with a nickel bath anode-cathode effect, I get a sort of dents on the mother plate.

Thanx My best regards.

Gummi
Process Technician - Borgloon, Limburg, Belgium
2003

---

You did not give us enough information. What kind of nickel plating electrolyte? etc. It reads like you have too much internal stress in the electroform which can be controlled by maintaining purity levels, pH, proper anodes, current density, agitation, temperature, halogen content. Come back with more data.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

2003

First off are you using equipment similar to the Digital Matrix type equipment? Are you using Nickel Inco s-pellets as your anode material? Is the dent in electroform only showing when the plating is completed or is this dent showing within minutes of starting to plate? Are you using just Nickel Sulfamate concentrate or using additives. Normally an electroform plate to 295 Microns in approximitely 52 minutes.if you a varying this high current requirement this could cause a problem.

Louis Hirbour
Anaheim, California, USA
2003

---

Please give us more details of your process, so we don't have to guess what you are using and doing.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2003

---

Hi Guys,

Coming more information, We are using 3 Digital Matrix Cells MC/1000. The solution we use is nickel sulfamate. For 3 Cells we have around 600 l. of solution. The solution is always circulating from cells to sump. The temperature is around 50 °c the baumé is 31.50 Ph is around 4.0-4.5. When the baumé is going up to 32-33 then I stabilize him with doing DI-water in the sump. Afcors the Ph then going up these I bring down with sulfamic-acid till 4.0-4.5. Also I do 2 monthly Carbon-treatment and after I take the carbon filters out I do also 500 ml. snap-am in for the surface tension and once a month I fill a sac in the sump with 1 kilo Boric Acid. We also take every 2 months samples for examination with Labo Hagestein in the Netherlands. always good result of our bath. The baskets in the cells whe fill with nickel-pellets supplied from Symcon. The father-son program duration is 64 minutes a max voltage from 15 v an the max amperage whe use is 50A. When we now cathodic cleaning a mother and passivate then we rinse the mother with hydrogen-peroxide and then DI-water. And then she going in the cell for 64 minutes till 50 Ah for 300 Micron and that in three steps.

Now : This has always worked very fine, and now we have since 3 months dents. but they are not always sometimes they are perfect and sometimes there are a few it always starts on the outside. and sometimes they are complete full of dents the surface is just like a golf terrain. the son is completely full of circles and on the mother are marks from that circles and when you polish the back from that stamper you get on the back that same circles as on the face from the stamper. so my stamper is actually completely full of dents.

What can I do about it ?

Regards,

Gummi
CD-DVD - Borgloon, Limburg, Belgium
2003

---

We believe that you have a nickel S contaminate supply problem. That you have some bad lot or lots of nickel. Your problem co-incides with our same time frame of problems. We have had absolutely no problems with our baths until also about (3) months ago. Back then we changed to a different lot of S pellets. And, in fact you described perfectly what we have seen here. Please have your nickel pellets tested for undue metal contamination. This will give the problem that you described.

Regards,

Jerry Davis
Makers of CD ROM, DVD, CD-R, DVD-R, - Tijuana, B.C. Mexico
2003

---

2003

Many CD manufacturers use S-Rounds and some use S-Pellets. I'll leave that discussion to those above.

How good is your sulfamic acid? How much Ammonium Ion is already in the sulfamic acid before you use it. Are you storing sulfamic acid in water where it immediately breaks down into ammonia. Add the dry powder directly to the bath.

What does the Hull Cell look like? In three months you can build up organics. This you can see on the Hull Cell. A 1 amp no agitation panel should be uniform matte dull down to 3 ASF.

Do you see a copper black bank across the top of the Hull Cell Panel? Have you dummied for copper. Even the best S-Rounds is loaded with copper.

What is the internal stress? What is the ammonium ion content?

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

If you change the anode material as suggested by an earlier response (from Mexico) and then dummy the bath, your problems will be solved. The effects you see are the result of grossly contaminated anode material. We've seen this problem a few times before as well.

Carl M. Rodia
- Trumbull, Connecticut, USA
2003