Multi-Level Metalization on Ceramic Substrates
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Solution Overview
Problem
Existing methods for producing metalized ceramic substrates with both high and low power areas on the same substrate are costly and inefficient, as they require expensive galvanic processing and multiple structuring steps, leading to unreliable connections and thermal dissipation issues due to thick copper structures and separate carrier substrates.
Innovation Solution
A method involving screen or pad printing of a glass-containing copper-based paste for a common base metalization, followed by reinforcement with copper paste in high power areas, annealing, and mechanical leveling to create a multi-level metalization with varying thicknesses, ensuring good thermal conduction and adhesiveness, while maintaining a smooth surface for high power areas and lower current-carrying capacity for low power areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If thick copper layers (200-300 μm) are used for high power areas, then current-carrying capacity is improved, but thermal dissipation becomes problematic and requires separate carrier substrates
Solution Approach 1:
The patent applies different copper layer thicknesses to different areas of the same substrate: thick copper layers (200-300 μm) in high power areas for current conduction, and thin copper layers (5-20 μm) in low power areas for signal transmission. This local differentiation allows thermal management in high power areas while maintaining electrical performance throughout the substrate.
Solution Approach 2:
The patent creates multi-level metalization structures by building copper layers at different heights on the same substrate plane. High power areas have elevated thick copper layers while low power areas have thinner copper layers at lower heights, creating a three-dimensional metalization architecture that solves thermal and electrical requirements simultaneously.
2Quantity of substance
If separate carrier substrates are used for power and control components, then current-carrying capacity is improved, but connection reliability deteriorates due to wire connections
Solution Approach 1:
The patent merges power areas and control areas onto a single ceramic substrate with integrated multi-level metalization. Thick copper layers for power conduction and thin copper layers for control signals coexist on the same substrate, eliminating the need for wire connections between separate substrates and improving overall connection reliability.
Solution Approach 2:
The ceramic substrate acts as an intermediary platform that integrates both high power and low power circuitry. The substrate's thermal and electrical properties mediate between the different requirements of power and control components, allowing direct electrical connections without external wire bonds.
3Quantity of substance
If multi-level metalization with varying thickness is produced using galvanic processing, then current-carrying capacity is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent replaces complex galvanic (electrochemical) processing with screen printing technology to create multi-level metalization. Screen printing allows direct deposition of copper paste in predetermined patterns and thicknesses without requiring multiple electrochemical deposition steps, plating resists, or photo-optical development processes.
Solution Approach 2:
The patent controls copper layer thickness by varying printing parameters such as screen mesh count, printing pressure, paste viscosity, and number of printings rather than controlling electrochemical deposition parameters. This changes the manufacturing approach from chemistry-based thickness control to mechanics-based thickness control, simplifying the process.
4Manufacturing precision
If multiple structuring steps with plating resists and photo-optical development are used, then metalization precision is improved, but productivity decreases and cost increases
Solution Approach 1:
The patent replaces photo-optical development and chemical etching processes with direct screen printing. The screen itself defines the pattern geometry, eliminating the need for photoresist application, UV exposure, chemical development, and resist stripping steps, thereby dramatically improving productivity.
Solution Approach 2:
The copper paste is prepared with predetermined rheological properties and particle size distribution before printing, allowing direct deposition in the final pattern geometry. This preliminary preparation of the paste eliminates the need for subsequent pattern definition steps required in galvanic processing.
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 method allows for the simultaneous production of high and low power areas on a single ceramic substrate with enhanced thermal conduction and adhesiveness, improving the reliability and efficiency of power modules by maximizing contact surface area and thermal dissipation.
Implementation Method 1
c) annealing of the metalized ceramic substrates with the high power and low power areas together at 850 to 950° C. under nitrogen
Data Source
AI summary
A method for producing a copper multi-level metallization on a ceramic substrate consisting of AlN or Al2O3. High power regions with metallization having a high current-carrying capacity and low power regions with metallic coatings having a low current-carrying capacity are created on one and the same ceramic substrate. The metallization is printed multiple times in the high power range.