Copper-Bonded Ceramic Substrate Structure for Partial Discharge Suppression
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Solution Overview
Problem
Conventional bonded substrates face challenges in preventing electrical breakdown due to partial discharge starting at defects exposed on the surface of silicon nitride ceramic substrates, which are difficult to detect and reduce.
Innovation Solution
A bonded substrate configuration where a copper plate and a bonding layer fill 80% or more of the volume of particle-defect holes exposed on the ceramic substrate surface, suppressing partial discharge and electrical breakdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional imaging methods are used to detect surface defects, then detection capability is limited, but expensive specialized equipment is required to detect defects with diameter of approximately 50 μm and depth of approximately 20 μm
Solution Approach 1:
The patent uses a cost-effective alternative to expensive specialized imaging equipment by employing standard imaging methods combined with a specific defect detection approach. Instead of requiring expensive equipment, the invention uses readily available imaging tools to capture surface defects, making the detection process economically viable for mass production while maintaining adequate detection capability for defects of approximately 50 μm diameter and 20 μm depth.
2Measurement precision
If partial discharge test is conducted to detect defects, then detection accuracy improves, but measurement difficulty and cost increase due to pA-order micro-current measurement requirements
Solution Approach 1:
The patent replaces the complex and expensive partial discharge test equipment with a simpler imaging-based detection method. Instead of measuring pA-order micro-currents that require specialized equipment and noise countermeasures, the invention uses standard imaging to directly visualize surface defects, significantly reducing measurement difficulty and equipment cost while maintaining effective defect detection capability.
Solution Approach 2:
The patent substitutes the electrical measurement approach (partial discharge test measuring micro-current) with an optical imaging approach. By replacing the electrical detection system with an optical system, the invention eliminates the need for complex micro-current measurement equipment and noise filtering systems, making the detection process simpler and more cost-effective.
3Reliability
If filtration of raw slurry is performed to reduce defects, then defect isolated in substrate is reduced, but defect exposed to surface cannot be prevented
Solution Approach 1:
The patent performs preliminary detection of surface defects using imaging methods before the bonding process. By identifying and documenting surface defects early in the manufacturing process, the invention enables selective handling or rejection of affected substrates before they undergo bonding, preventing defective products from reaching shipment stage while maintaining manufacturing efficiency.
Data Source
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AI summary
A bonded substrate includes a ceramic substrate, a copper plate, and a bonding layer. The ceramic substrate has a main surface having a flat region having a maximum height Rz of 10 µm or less. The ceramic substrate has a particle-defect hole being exposed to the main surface, imparting flatness lower than flatness of the flat region to a part of the main surface, and having a depth of 10 µm or more and 60 µm or less. The copper plate includes a first portion disposed over the flat region and a second portion filling the particle-defect hole. The bonding layer includes a third portion covering the flat region and a fourth portion filling the particle-defect hole, and the second portion and the fourth portion fill 80% or more of a volume of the particle-defect hole. The bonding layer bonds the copper plate to the main surface.