Evaporation boats for vacuum aluminum coating are core components for achieving metal (mostly aluminum) evaporation coating. Their usage specifications directly affect coating quality and service life, with the following key precautions to focus on:

1. Installation and Commissioning

• Ensure the evaporation boat makes tight contact with electrodes and bears uniform force. Avoid poor contact, which may cause local overheating or arc discharge and damage the boat body.

• Calibrate the position of the evaporation boat during installation to ensure a consistent distance from the substrate (e.g., film), preventing uneven coating thickness. Meanwhile, avoid collision between the boat body and other parts of the vacuum chamber to prevent physical damage.

2. Vacuum Environment Control

• Before coating, evacuate the vacuum chamber to the specified vacuum level (usually below 1×10⁻³Pa). Insufficient vacuum will lead to oxidation of the boat body, splashing of aluminum liquid, and also affect the compactness and gloss of the coating.

• Regularly maintain the vacuum system to prevent oil, impurities from entering the vacuum chamber, which would contaminate the surface of the evaporation boat and reduce heat transfer efficiency.

3. Temperature Rise and Current Control

• Adopt a "stepwise temperature rise" method. Avoid directly applying a large current, which may cause the boat body to crack due to thermal shock. The heating rate should be determined based on the material of the evaporation boat (e.g., aluminum nitride, zirconia), usually controlled at 5-10℃/s.

• Maintain stable current during the evaporation process. Avoid frequent startup/shutdown or sudden current changes to prevent the boat body from developing cracks due to local overheating, or the aluminum liquid from "aluminum spraying" caused by temperature fluctuations.

4. Aluminum Material Addition Specifications

• The aluminum material (mostly aluminum wire or aluminum pellets) must be clean and free of impurities. Avoid introducing oil, oxides, etc., which may cause pinholes, spots in the coating, or reactions between impurities and the boat body that shorten its service life.

• Add an appropriate amount of aluminum material each time. Prevent excessive aluminum material from overflowing the boat body and contaminating the vacuum chamber, or insufficient aluminum material leading to "dry burning" of the boat body (high-temperature heating without aluminum liquid), which accelerates the aging of the boat body.

5. Daily Maintenance and Replacement

• After each coating process, wait for the evaporation boat to cool down to room temperature before cleaning. Use special tools to remove residual aluminum dross inside the boat, and avoid scratching or abrading the surface of the boat body with hard objects.

• When the evaporation boat has obvious cracks, deformation, or frequent discharge and aluminum liquid splashing occur during the coating process, replace it in a timely manner. Do not continue to use it to prevent affecting coating quality or causing failures in the vacuum chamber.