Cleaning of copper wire

I think that most any way of cleaning the wire would be better long term than acid washing. I based this upon a problem a customer had several years ago that was perplexing at best. The wire 46 AWG with a polyester bondable material was being put into circuit boards that were going into F16's. Under microscopic examination the copper was corroding/oxidizing and you could actually see green colored copper oxide. Since this appeared to be starting at the conductor and "growing" until it damaged the insulation, it took a lot of work trying to discover what was causing the insulation to fail and the copper to oxide. Since the wire was used to form the circuits on the board, insulation failure typically fried other devices or circuits.

Eventually it was discovered that the boards were wound by female employees. When it was that time of the month there was a chemical/pH change in the body/finger oils. When someone's fingers touched the wire, it left a thin layer of body oil. When the wire was embedded in the board the oil was encased and sealed into the board coating where it continued to work on the wire. Eventually the insulation was breached and the oils then attacked the conductor. Eventually there was a failure and it occurred in about one year. Sound unreal but it happened.

I could see the opposite here. You are cleaning the wire with acid. Nothing was said about washing it off, If the acid is not removed, would it continue to react with the copper and perhaps the insulation?

Long story to ask that question.

Spectre

Spectre,

The “Purple Jet” was an early application of a similar system dedicated for enameling applications.

The Plasmait system is significantly more potent and technologically more advanced than the MAG version.

We had a system on display in Cleveland, earlier this year.

Best Regards,

Willy

Willy,

Is this the same type plasm "annealer" that MAG was offering a couple of years ago? I think it was the last time there was a show in Atlanta.

The Boockmann unit was originally designed to lubricate wire. The thread/fiber was like waxed dental floss and as the warm wire went towards the spool the floss was wrapped around the wire and applied the lubricant to the wire. The primary benefit was that it was a 'dry" lubricant and produced no fumes or air pollution. It has not been unusual for an enameling system to produce more VOC's from the lubricant system than from a properly working oven/catalysts/fume incinerating system.

Later the Boockmann system's floss was changed so that it could be used to clean bare wire.

While clean wire is essential to good adherence, I think that if you have to resort to something as harsh, dangerous, and environmentally unfriendly as an acid wash you really have a lubricant problem. There are enamels much harder to apply than Formvar and they don't require acid cleaning the wire.

spectre

Greetings from Toronto,

The consensus is, in any case, that the wire surface needs to be extremely clean if best performance of to be assured.

Whilst the Boockmann will do an excellent job on the “rough” work it certainly will not prepare the wire for enameling quality surface.

Plasma cleaning/annealing has a number of advantages: in-line operation, no chemicals needed, high operational speeds, low power consumption, low maintenance requirements, low gas consumption, environmentally friendly and operational ease through recipe control.

Also very important to note is the capability of plasma to clean and anneal in the same system.

Best Regards,

Willy Hauer

Howar Equipment Inc.
www.howarequipment.com

Mark C, Peter,

what you are doing is a basic wire enameling job. I cannot think of any reason in the world why you would be using an acid wash or any type to clean the wire. Formvar is one of the oldest wire enamels, not quite as old as shellac or oleo resinous materials but nearly. GE has coated millions maybe even billions of pounds of copper and aluminum conductor and I would venture to guess that not a single pound was cleaned with an acid wash!

It is essential that the conductor be cleaned. If it is not you will get an adherence failure which means exactly what it sounds like; the enamel, in this case Formvar has cured but is not sticking to the conductor.

From past discussions I have mentioned an annealer or pre-annealer. I think I also said that one of the things that it does is clean the wire. The pre-annealer is designed so that electrically heated ones have an induced atmosphere such as steam or nitrogen. Gas fired annealers generally have a reducing gas atmosphere (0% oxygen and 5-10% reducing atmosphere due to the burner being set in a rich gas condition.) some annealers have a water seal and when the hot wire hits it, steam is produced creating an atmosphere.

You say that this type insulation requires an extremely clean surface but in reality all enameling processes require a clean surface. If your wire is that dirty, I think you need to take a look at your wire drawing lubricant.

Again, there is no reason in the world that I can think of after 30+ years in the industry that I would even consider using an acid (or alkali ) bath to clean bare wire for enameling.

Another thought is how do you neutralize the acid on the copper wire. Also is it possible that you are using (the end result) unknowingly, the acid wash to etch the cooper so that there is a more irregular surface which then provides more surface area for the enamel to adhere to?

richard

Hello Mark,

One option is Plasmait GmbH (Austria) ( www.plasmait.com/ ) represented in North America by ( www.howarequipment.com/ ) Willy Hauer in Toronto. Take a look at this Plasmait page; www.plasmait.com/index.php?page=5

A simpler but perhaps less effective process would be Boockmann GmbH (German) ( www.boockmann.com/ ) Just click on "English" and then on "Helicord". This little unit is used for a whole bunch of different applications. The Slover Group represents Boockmann in North America and you can find all that information on the Boockmann web site.

Finally there is the Cable Consultants Corporation Primary Wire Wipe. This smart looking machine is designed to clean non-ferrous solid or stranded wire from 18 to 30 AWG at speeds up to 8000 FPM. www.cableconsultantscorp.com/primary.htm

Finally look at this WAI Forums thread; www.wirenet.org/forum/viewmessages.cfm?Forum=12&Topic=407 for back-up information.

Sincerely,
Peter J. Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com