Going For The Gold

[gsw3]

Hey guys, I need any tips you have learned on immersion gold plating using Caswell's 24ct gold plating solution and 24ct gold anode (or using the S/S anode).

I have Caswell's manual (version 4) however, would like some first hand information/tips from anyone who has been doing this for awhile.

I have been nickel plating very small electrical contacts (about .125 to .250 Sq. In. in surface area) for the medical company I work for.
This is a "no brainer" job for me and have been doing it for years.

Today I was approached about the possibility of gold plating them (instead of nickel).

Reason? These new contacts will be in a highly magnetic environment (used in an MRI bore) which dictates not using any magnetic material, thus no nickel permitted (will show up as artifacts on MRI films) and the production plating company wanted $160.00 each to gold plate them in the small quantities and fast turn-around that we require.

I will be immersion plating them on a small electrically charged rotating hanger rack which holds (6) contacts each.
Anode: 24ct gold (for now at least, let me know your thoughts using the S/S anode)
Base Material: Beryllium copper.
Part area: .18 Sq. In. (each contact)
No nickel strike coat allowed since they will be used in a MRI bore.
Total quantity of parts to be plated: 24 pieces.

I already have the P.O. cut for the gold solution and anodes from Caswell, will be ordering the supplies on Monday and need any info fast since these must be finished by next Thursday (Feb. 17th).


George W.
Orlando, Fl

[jimcarry]

George
Well the obvious is that the ss anode is cheaper for you so the profits are better. And I don’t see where it would create a problem I use ss all the time for selective plating on car emblems, tools, even some costume jewelry for my kids .

[gsw3]

Jim, thanks for replying, however, no one responded in time so I just went ahead and used the gold anode.

The main concern for the post was the fact that I could not put down a nickel base plate prior to the gold due to magnetic restrictions.
I was concerned that the lack of the nickel plate may adversley effect the finish/durability of the final gold.

BTW, we test parts that will be in the MRI bore with a magnet so frigging strong it will pick up a piece of 360 brass! (360 brass has approx. 0.35 percent iron in it).
If the magnet can even move the part on the table (let alone pick it up) it is not suitable for use in the bore.

I plated a test piece of totally non-magnetic brass, plated nickel on it for (3) minutes and the test magnet picked it right up! Failed!
So no nickel at all could be used on these contacts.

I ended up tumble burnishing the tiny Beryllium copper contacts to bring them up to a super smooth/polished finish and they turned out looking great without the nickel (but the nickel underplate on the test pieces I ran looked even better of course).

Since we were taken over by a big corporation I will not be able to do any producton runs on the gold plating due to the companies policys on "qualified vendors".
There is a ton of paperwork to fill out, you must have a real business, blah, blah, blah.

So....I do the prototype plating work only.

George W.
Orlando, FL

[dadkar2]

George,

Very tough problem. Eventually the copper will migrate right through the gold, which is why the nickel barrier is often used. Not sure how thick you'd have to make that gold to give a reasonable lifetime. Perhaps this calls for a solid gold contact with a separate beryllum copper spring.

There is a company in Austin (TerraVicta), that is manufacturing a MEMS device that might work if your contact power is under .5 watts switched.

rfdesign.com/mag/radio_mems_wireless_apps/ - 30k

What did the production supplier recommend doing?

Ken