Decoating solution, process, and device for wet chemical removal of a PVD or CVD titanium nitride layer from a hard-metal substrate

A decoating solution for wet-chemical removal of a PVD or CVD titanium nitride layer from a hard-metal substrate, the decoating solution comprising:

• 70-85 wt % of water,
• 1-10 wt % of a hydrogen compound other than water, and
• 10-20 wt % of an ammonium salt,
• wherein the decoating solution has a pH of less than 7 at room temperature.

A decoating method of wet-chemical removal of a PVD or CVD titanium nitride layer from a hard-metal substrate comprising:

• a step of immersing a workpiece, comprising a hard-metal substrate coated with a PVD or CVD titanium nitride layer, in a solution comprising water and an ammonium salt;
• a step of delivering a hydrogen compound other than water to the solution to form a decoating solution comprising (i) 70-85 wt % of water;
• (ii) 1-10 wt % of a hydrogen compound other than water, and (iii) 10-20 wt % of an ammonium salt, and having a pH of less than 7 at room temperature;
• and
• a step of swirling the workpiece in the decoating solution for a predetermined period of time;
• wherein the decoating solution has a temperature above room temperature during the step of swirling the workpiece in the decoating solution.

A decoating device for the wet-chemical removal of a PVD or CVD titanium nitride layer from a hard-metal substrate, comprising:

• a container for holding a decoating solution comprising (i) 70-85 wt % of water;
• (ii) 1-10 wt % of a hydrogen compound other than water, and (iii) 10-20 wt % of an ammonium salt, and having a pH of less than 7 at room temperature;
• and
• a drum, configured to receive a workpiece and to rotate in the container (12),
• wherein the drum is configured to be at least partially immersed in the decoating solution and rotated therein.