Balanced Triaxial Grounding for Glass Coating Crazing Reduction
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Solution Overview
Problem
Crazing, or 'lightning arc defects,' occurs in glass coatings due to parasitic currents exceeding the thermal capacity of the film, leading to defects that can render the glass unusable.
Innovation Solution
A deposition system with a balanced triaxial cable connection and a low impedance path to ground for parasitic currents, which diverts these currents away from the substrate, reducing the conditions that cause crazing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional coating deposition is used in plasma chambers, then coating efficiency and homogeneity are improved, but parasitic currents cause crazing defects that ruin the glass substrate
Solution Approach 1:
A grounded triaxial cable is introduced as an intermediary component between the power supply and the sputtering target. The cable's conductive shield provides a controlled path for parasitic currents to flow to ground, preventing these currents from causing crazing defects on the glass substrate while maintaining the coating deposition process
Solution Approach 2:
The harmful parasitic currents are extracted from the substrate by providing an alternative path through the grounded triaxial cable. The conductive shield of the cable captures these currents before they can reach the substrate, effectively removing the harmful effect while preserving the useful coating deposition function
2Productivity
If high power is applied to sputtering targets to increase deposition rate, then coating speed is improved, but parasitic current flows increase causing more crazing defects
Solution Approach 1:
The grounded triaxial cable converts the harmful parasitic currents into a beneficial controlled flow to ground. The conductive shield captures the parasitic currents that would otherwise cause crazing and redirects them through a safe path, transforming a destructive effect into a controlled electrical flow that protects the substrate
3Device complexity
If conventional cable connections are used between power supply and deposition chamber, then system simplicity is maintained, but parasitic currents cannot be effectively diverted causing coating defects
Solution Approach 1:
The grounded triaxial cable serves as an intermediary connection between the power supply and deposition chamber. It maintains the electrical connection needed for the coating process while simultaneously providing a controlled path for parasitic currents through its conductive shield, thus protecting coating quality without significantly increasing system complexity
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 effectively reduces parasitic current flows in the substrate and coating, thereby minimizing crazing defects and ensuring the quality of the glass coatings.
Implementation Method 1
the first triaxial cable and the second triaxial cable provide capacitive or low impedance paths to ground for parasitic current otherwise causing defects on a substrate being processed in the glass coating system
Implementation Method 2
A deposition system with a balanced triaxial cable connection and a low impedance path to ground for parasitic currents, which diverts these currents away from the substrate
Data Source
AI summary
A coating system that reduces parasitic currents that may cause crazing in coatings on a substrate. In one example, the system includes a pair of low impedance shunt paths to ground for parasitic AC currents generated from the plasma in the chamber. The low impedance shunts may be provided through a balanced triaxial connection between a power supply of each chamber and the magnetrons of each chamber. In another example, potential differences between adjacent chambers are minimized through synchronized power supply signals between chambers.