Magnetron-Sputtered Silver Mirror for High Solar Reflectivity
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Solution Overview
Problem
Existing mirror technologies face challenges in achieving high reflectivity across the solar spectrum, particularly in the visible and infrared range, which is crucial for efficient solar energy collection, as the reflectivity of silver layers is not optimized under current deposition methods.
Innovation Solution
The method involves depositing a silver layer by magnetron sputtering with a specific range of pressure and distance between the target and substrate, combined with a bonding layer and protective layers to enhance adhesion and resistance, and applying heat treatments like quenching and bending to increase reflectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If liquid means are used to deposit the silver layer from a silvering solution, then the deposition process is simple and cost-effective, but the reflectivity of the silver layer across the solar spectrum is not optimized
Solution Approach 1:
The patent changes the deposition method from liquid silvering solution to magnetron sputtering, and optimizes physical parameters including pressure (0.05-3 Pa), target-substrate distance (5-20 cm), and power density (0.2-1.1 W/cm²) to achieve enhanced reflectivity greater than 70% across the solar spectrum while maintaining manufacturing feasibility
2Loss of substance
If the silver layer is made thinner to reduce material cost, then the amount of silver used is reduced, but the reflectivity and durability of the mirror decreases
Solution Approach 1:
The magnetron sputtering process with optimized parameters (pressure 0.05-3 Pa, power density 0.2-1.1 W/cm², target-substrate distance 5-20 cm) enables deposition of thin silver layers (50-200 nm) that achieve reflectivity greater than 70% across the solar spectrum, maintaining durability while reducing silver consumption compared to traditional thicker deposits
3Strength
If heat treatment is applied to the mirror to improve substrate properties, then the substrate strength is improved, but the silver layer degrades and reflectivity decreases
Solution Approach 1:
The silver layer is deposited by magnetron sputtering with optimized parameters (pressure 0.05-3 Pa, power density 0.2-1.1 W/cm², target-substrate distance 5-20 cm) before heat treatment, creating a robust silver layer that can withstand subsequent heat treatments for substrate tempering or bending without degradation, as the magnetron-deposited layer has superior adhesion and thermal stability
4Manufacturing precision
If the target-substrate distance is reduced to improve deposition uniformity, then the deposit uniformity is improved, but the pressure control becomes more critical and deposition rate increases
Solution Approach 1:
The patent specifies a target-substrate distance of 5-20 cm combined with pressure control at 0.05-3 Pa during magnetron sputtering, creating optimal deposition conditions that achieve uniform silver layer coverage while maintaining controllable deposition rates through the balanced parameter combination
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 approach results in a silver layer with reflectivity greater than 80% between 295 and 2500 nm, improving the efficiency of solar energy collection and durability of the mirror, while allowing for heat treatments without degrading the silver layer.
Implementation Method 1
The deposition of the silver layer is carried out by sputtering silver from a silver source, and in particular by the so-called magnetron cathode sputtering process
Implementation Method 2
A voltage of a few hundred volts is applied between the target and the frame of the installation. The deposition takes place under an electric field and a magnetic field
Implementation Method 3
The deposition takes place under an electric field and a magnetic field
Implementation Method 4
The deposition of the silver layer is carried out by sputtering silver from a silver source... in an enclosure under a deposition atmosphere comprising a rare gas
Data Source
Figure 1~2
AI summary
The invention relates to a method for manufacturing a mirror comprising the depositing of a layer of silver by magnetron cathode sputtering from a silver target area on a substrate in a deposition atmosphere comprising a rare gas, wherein the product of the deposition atmosphere pressure by the distance between the target area and the substrate is comprised between l.5 Pa.cm and 7 Pa.cm. Very highly reflective mirrors, greater than 70% between 295 nm and 2500 nm (measured according to the ISO 9050 standard, air mass 1.5) are thus obtained. They are particularly adapted to reflecting sunlight for collecting solar energy.