"Finger Prints" on Titanium Nitride Coatings

A. It is much cheaper to wear clean white gloves and prevent the fingerprints than it is to remove them.

A. The only solution to your problem is to prevent fingerprints using gloves in the first place. You may try polishing the surface and redepositing some more TiN. The fingerprints result is different crystal orientation and structure of the deposited layer at the contaminated site, does not matter what material you deposit. This phenomenon is not just limited to PVD.

A. I think if you handle your components with finger stalls or banian hand gloves you won't get that problem.

Regards,

A. PVD coating, when applied properly, will mimic the surface finish of the substrate. If you cannot remove the marks with acetone ⇦this on eBay or Amazon [affil links] Warning! highly Flammable! , then the part was not properly cleaned before coating. There is a possibility that the areas not correctly prepared will have a weaker bond than other areas. You should be able to strip the parts and recoat.

Color is not always a good indication of the actual bond. There are several techniques to apply PVD, variations can occur when the parts are not subjected to ion bombardment in an equal fashion.

A. The fingerprints should be removed before sputtering TiN in the precleaning process otherwise it would give a faulty deposit.I would suggest that it should be prevented by using good set of gloves while handing your component before plating at all steps.To get a good hard coating ,u can increase the Nitrogen flow during deposition which would also darken the color of coating.

A. In PVD coating of TiN, particularly deposited by arc evaporation, the layer builds up in a columnar fashion. The cross section of the coating seen under very high magnification will show peaks and valleys corresponding to the column and the interspace between columns. The recesses act as receptacles to the sweat of the fingers leading to the finger print marking on the surface.

The problem can be overcome by resorting to the following:

(a) Ionic bombardment towards the end of the coating cycle in a magnetron sputtering equipment helps to level of the microscopic peaks and produces a smoother coating that has better reflectivity.This will minimise the retention of sweat on the surface.
(b)As mentioned in an earlier reply posted, cleaning with acetone ⇦this on eBay or Amazon [affil links] Warning! highly Flammable! will help to remove the stain. Of course, needless to say, the coated workpiece needs to be handled with clean gloves.
(c) Coating with a lacquer is a temporary solution, but it needs to be removed before use.
(d) Some go for a gold flash on top of the TiN to overcome the problem. However this is limited to decorative application.

A. Since the fingerprints can be removed by acetone it sounds like the reason that you get fingerprints is that the coating is porous and adsorbs grease, etc. The porosity can be decreased using ion bombardment during deposition (ion plating) to densify the film. The color has more to do with stoichiometry than with hardness or adhesion.

A. To remove finger-print, use disposable plastic gloves ⇦this on eBay or Amazon [affil links] after cleaning of substrate (item to be coated) is completed. Handle the item with this gloves while loading in the coating chamber.

A. I had a similar problem. There were finger prints even after cleaning the surface and the marks were visible even after coating. I tried ultrasonic cleaning of the sample in acetone ⇦this on eBay or Amazon [affil links] Warning! highly Flammable! and it worked. However make sure that there is no oxide formation on the surface(especially along the finger marks) before it goes into acetone as this would aggravate the surface further.

The general procedure I follow is to strip the protective coating in an acidic solution. And then immersing in water (3 diff. beakers [beakers on eBay or Amazon [affil links] in sequence) to isolate any acid and then immediately into acetone ⇦this on eBay or Amazon [affil links] Warning! highly Flammable! assisted with ultrasonic cleaning (couple times is fine also)to isolate any water on the surface. It is important to prevent any drying of the sample surface while transferring between diff beakers since an active surface in air can oxidise quickly.

The sample can be air dried at the end of the acetone cleaning.

A. You can use nano coating and depending upon the material or the base material this can be fired or non firing type.

A. Hi Beata. As Dr. Verma notes, there are nano coatings which discourage fingerprints. You can google for them. But you should wear gloves until sale or shipment, and no nano-coating will be quite as nice as real gold on the surface :-)

Regards,