Evaporator Bank Herringbone Pattern for Coating Uniformity
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Solution Overview
Problem
Existing methods for coating strip-shaped substrates with evaporator banks result in uneven layer distribution due to overlapping vapor lobes, leading to inefficiencies and suboptimal layer thickness uniformity.
Innovation Solution
The evaporator bank is arranged in a herringbone pattern with set A boats angled between -2° and -10° and set B boats angled between 2° and 10° relative to the substrate's direction, with each set having varying lengths and arranged within a specific width, to reduce layer thickness fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If evaporator boats are arranged parallel to one another along the direction of travel, then the coating process is simple and efficient, but the layer thickness uniformity deteriorates due to overlapping vapor lobes
Solution Approach 1:
The evaporator boats are arranged asymmetrically at angles of 5-15 degrees relative to the substrate travel direction, breaking the parallel symmetry. This asymmetric arrangement causes the vapor lobes to overlap in a controlled manner, filling in the minima regions and reducing layer thickness fluctuations from +/-5% to +/-2.5% while maintaining coating efficiency
2Manufacturing precision
If evaporator boats are arranged offset from one another to improve layer uniformity, then layer thickness uniformity improves, but coating efficiency deteriorates
Solution Approach 1:
The invention changes the geometric parameters of the evaporator boat arrangement by introducing angular orientation (5-15 degrees) and varying lengths (LA and LB within ranges L0-δA and L0-δB). This parameter optimization allows the vapor lobes to interact constructively, achieving both improved layer uniformity (+/-2.5%) and maintained coating efficiency through the herringbone pattern configuration
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This arrangement significantly improves layer uniformity by narrowing the intensity distribution of vapor lobes, reducing layer thickness fluctuations from +/-5% to +/-2.5%, as demonstrated by simulation calculations and real coating experiments.
Implementation Method 1
The vaporizing material, preferably aluminum, forms a vapor lobe with a characteristic intensity distribution or emission characteristic of the vaporized material over the individual vaporizer boats
Implementation Method 2
the downward side of the substrate is coated with metal evaporated in the evaporator boats
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
Disclosed is an apparatus for coating a strip-shaped substrate that can be moved in a direction of travel X during the coating process. Said apparatus comprises a number of evaporation boats forming an evaporation bench, a device for electrically heating the evaporation boats, and a device for feeding wire that is to be evaporated to the evaporation boats. The number of evaporation boats is formed by a set A and a set B of evaporation boats. The evaporation boats of set A have a length LA ranging from LO - d A to LO + d A while the evaporation boats of set B have a length LB ranging from LO - d B to LO + d B. The number of evaporation boats are arranged in the direction X within an area that extends parallel to the direction Y and has a maximum width of 2 LO + d A + d B. The evaporation boats of set A and set B are alternately disposed next to one another. Furthermore, the evaporation boats of set A are arranged at an angle a ranging from -1° to -89° relative to the direction X while the evaporation boats of set B are arranged at an angle ß ranging from 1° to 89° relative to the direction of travel X. The invention also relates to a method for designing an apparatus used for coating a strip-shaped substrate.