PVD aperture ratio and platability - aspect ratio

01 What is the pore size ratio of PVD #

Aperture ratio (thickness-to-diameter ratio, aspect ratio), aspect ratio, empirical value of PVD vacuum coating, aperture depth: aperture ＜1:1, and the value of aperture depth can not be larger than the aperture, otherwise it is very difficult to be coated. The deeper the film is, the shallower it is, and different coating types and process depths are not the same. But in general, PVD is not suitable for plating internal holes. Usually in the hole diameter is less than 6mm, the inside of the hole is difficult to plating; on the contrary, the larger the hole diameter, the greater the probability of being able to plating into.

Deep hole plating can be improved by rotating the fixture in two dimensions. As shown in the figure below, when rotating in two dimensions, both ends of the hole can be plated, and the further to the center of the deep hole, the thinner the film layer is, or it cannot be plated.

• The hole ratio is 1:1; however, the larger the true opening size of the workpiece, the deeper it can be plated;
• Titanium nitride has excellent winding plating properties;
• It is possible to rotate the workpiece and coat both ends;
• HiPIMS can exceed 1:2; however, applications are limited;
• DLC hollow cathode technology is available; and electrodes are inserted deep inside the workpiece chamber; customized equipment is available for workpiece-specific applications;

PeCVD has better winding than PVD, but still not suitable for plating deep holes.PeCVD DLC gears, the inner wall obviously appear dazzling color.DLC film thickness lower than 1 micron, it will appear obvious color. And with different film thicknesses, the colors presented are different.

02 Titanium Nitride Coatings with Excellent Winding Properties #

PVD Titanium Nitride coatings, especially on slotted parts, can clearly break the 1:1 rule. For the slotted parts in the picture below, you can see that only the innermost corners have obvious whitening, while the other colors are relatively uniform. Nasi usually uses composite yellow titanium, and the priming and intermediate layers are 1-2 microns, while titanium nitride is no more than 1.5 microns. Therefore, if the coating time is extended, such workpieces with slots on both sides can be plated.

03 Vacuum coating bore process #

Domestic has the highest 16:1 PVD deep hole coating machine, proofing fee 20,000 furnace, Lingxi did not have the opportunity to try. Legend has it that it has been mass-produced. But China's industry prefers cheap volume of industry, and scale advantages, such as niche coating machine market is limited. Vacuum coating technology in theCVDAnd its extension such as LPCVD and other chemical vapor deposition processes, can be plated inside the hole, and the gas can reach the area can be plated. But the film thickness of internal control is still only about half of the outer wall. And usually not the same application scenarios as traditional PVD.

04 Example of PVD titanium nitride coated molds #

Electron gun PVD is suitable for mold coating, no droplets on the surface, dense film, good wrap-around plating, one of the mirror mold coating process for Nasi.