Discontinuous Metallic Coating for Millimeter Wave Transparency
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Solution Overview
Problem
Conventional methods for forming metallic coatings with a sheen and discontinuous structure for millimeter wave radar applications are costly and lack stability, with existing solutions either requiring costly post-processing treatments or failing to maintain a stable discontinuous structure.
Innovation Solution
A resin product with a metallic coating comprising chromium (Cr) or indium (In) deposited using a physical vapor deposition method on an inorganic undercoating, which includes compounds like titanium oxide or silicon oxide, to achieve a sheen and discontinuous structure suitable for millimeter wave transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a physical vapor deposition method is used to form a metallic coating with a continuous structure, then a metallic sheen is achieved, but the coating blocks or greatly attenuates millimeter waves
Solution Approach 1:
The metallic coating is divided into discrete metal particles distributed across the surface rather than forming a continuous layer. These particles are spaced apart to allow millimeter waves to pass through while still reflecting visible light to provide metallic sheen. The segmentation is achieved through controlled physical vapor deposition parameters and substrate preparation.
2Object-affected harmful factors
If post-processing treatment such as etching using masks is applied to create a discontinuous structure, then millimeter wave transparency is improved, but treatment costs increase
Solution Approach 1:
The discontinuous structure is formed during the initial physical vapor deposition process rather than as a subsequent post-processing step. By controlling deposition parameters such as substrate temperature, deposition rate, and metal flux, the metallic coating naturally forms as discrete particles on the substrate without requiring additional etching or masking operations.
3Shape
If the treatment is stopped in a state of an ultra-thin film before metallic coating formation, then a discontinuous structure is obtained, but a metallic sheen that is adequate in terms of external appearance cannot be obtained
Solution Approach 1:
The physical vapor deposition parameters are optimized to control the size, distribution, and reflectivity of metal particles. By adjusting deposition temperature, metal flux rate, and substrate conditions, the coating achieves both discontinuous structure for millimeter wave transparency and sufficient particle density for metallic sheen. The particle size is controlled to be in the range that provides both structural discontinuity and optical reflectivity.
4Ease of manufacture
If an In or Sn coating is formed by using a physical vapor deposition method, then a discontinuous structure is formed without post-processing treatment, but a sufficiently stable discontinuous structure cannot be maintained when taking into account coating-thickness dependence
Solution Approach 1:
The patent uses chromium metal particles as the coating material, which provides superior stability and adhesion compared to softer metals like indium or tin. The chromium particles maintain their discontinuous structure and provide long-term durability and corrosion resistance, making them a more reliable choice for permanent coatings on automotive and industrial applications.
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
The solution provides a high-productivity, low-cost metallic coating with enhanced millimeter wave transparency and corrosion resistance, maintaining a stable discontinuous structure suitable for various applications including millimeter wave radar apparatus covers and automotive components.
Implementation Method 1
a metallic coating deposited on the inorganic undercoating by using a physical vapor deposition method
Data Source
AI summary
The present invention provides a metallic coating having a sheen and discontinuous structure and a resin product having the metallic coating by using a physical vapor deposition method at high productivity and low cost.