What are the common appearance defects of PVD coating equipment?

PVD coating is a commonly used tool coating in industrial production. With the improvement of industrial production level, the requirements for tool coating are getting higher and higher. Although the equipment and methods are constantly improving, there are still some shortcomings in the equipment process. What are the common appearance defects of PVD coating equipment?

1. Large droplet

It is a typical defect of PVD coating equipment in the process of high-energy ions bombarding the target to obtain high stacking power. Generally, the three-dimensional scale of particles is relatively uniform, greater than 1.5 um. It is a coating defect that seriously affects the machining accuracy of tools, and has an impact on the repeated positioning accuracy of tools and the appearance quality of machined parts.

2. Nodules and sheet protrusions

It is because the particles in the vacuum chamber or particles on the surface of the substrate once adhered to the surface of the substrate when they were stacked in the coating and then existed in the coating. It is often a relatively soft coating defect. The area scale of the defect is often much larger than the height, and it is easy to peel off in application.

3. Empty or discoid pit

In PVD coating, there are foreign particles that are not firmly bonded with the coating, which fall spontaneously under the effect of high stress, forming a void defect; There is pollution between the substrates, which falls due to the thermal stress effect when the vacuum chamber cools, forming a disk shaped pit or exposing the substrate.

4. Pinholes or bubbles

When there are narrow pits on the surface of the substrate, the coating will grow preferentially on the edge of the pits during the deposition process, gradually forming the coating pinhole defect. When the surface is polished, a thin layer of coating on the surface of this defect is worn off and exposed. Bubbles are 100-400nm micro particles, which form sheets in the vacuum chamber. When they pass through the plasma, they can get charges. Such ions can reach the surface of the matrix, and are fixed on the surface of the matrix under the effect of charges. Bubble defects are formed during the accumulation process.