Evaporation vacuum coating machine and physical principle introduction- Ningbo Honyu Vacuum Technology Co., Ltd.

Evaporation vacuum coating machine and physical principle introduction

The evaporation vacuum coating machine is mainly composed of a vacuum chamber and a vacuum pumping system. The vacuum chamber contains an evaporation source (ie, an evaporation heater), a substrate and a substrate holder, a substrate heater, a power supply, an evaporation boat, and an electrode rod. The vacuum system includes rough pumping, intermediate pumping, fine pumping, etc., including mechanical pump, Roots pump, diffusion pump or molecular pump.

The coating material is placed in the evaporation source in the vacuum chamber. Under high vacuum conditions, the evaporation source is heated to evaporate it. When the mean free path of the vapor molecules is greater than the linear size of the vacuum chamber, the atoms and molecules of the film vapor will evaporate from the evaporation source. After the source surface escapes, it is rarely collided and hindered by other molecules or atoms, and can directly reach the surface of the substrate to be plated. Due to the low temperature of the substrate, the vapor particles of the film material condense on it to form a film.

In order to improve the adhesion between the evaporated molecules and the substrate, the substrate can be activated by appropriate heating or ion cleaning. The physical process of vacuum evaporation coating from material evaporation, transportation to deposition and film formation is as follows:

(1) Use various methods to convert other forms of energy into heat energy, heat the film material to evaporate or sublime, and become gaseous particles (atoms, molecules or atomic groups) with a certain energy (0.1~0.3eV):

(2) The gaseous particles leave the surface of the membrane material and are transported to the surface of the substrate in a straight line with a substantial movement speed without collision;

(3) The gaseous particles reaching the surface of the substrate condense and nucleate and grow into a solid film;

(4) The atoms constituting the thin film are rearranged or chemically bonded.

The daily vacuum coating machine uses evaporation technology to coat aluminum, magnesium fluoride, gold, silver, etc., because they have the advantage of low melting point, which is convenient for rapid evaporation and sublimation.