Ceramic Circuit Board Brazing Without Ag for Thermal Cycle Durability
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Solution Overview
Problem
Ceramic circuit boards face challenges in maintaining high thermal cycle test (TCT) characteristics due to increased operating temperatures of semiconductor elements, particularly with existing bonding methods that include silver, which lead to poor durability and increased chemical liquid replacement frequencies.
Innovation Solution
A method for manufacturing ceramic circuit boards using a brazing material layer without silver (Ag), comprising copper (Cu), titanium (Ti), and either tin (Sn) or indium (In), where the brazing material is etched using a hydrogen peroxide and ammonium peroxodisulfate etchant with a pH between 4 and 12, and the bonding process includes copper etching and chemical polishing to control the bonding layer's size and shape, enhancing thermal conductivity and bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a brazing material layer containing silver (Ag) is used for bonding copper members to ceramic substrates, then bonding strength is achieved, but thermal cycle test characteristics deteriorate and chemical liquid replacement frequency increases
Solution Approach 1:
The invention extracts and removes silver (Ag) from the brazing material layer composition. The brazing material layer now consists of copper (Cu), tin (Sn), and zinc (Zn) without any silver content. This extraction eliminates the harmful effects of silver-related intermetallic compound formation that causes poor TCT characteristics and frequent chemical liquid replacement, while maintaining effective bonding through the Cu-Sn-Zn system.
Solution Approach 2:
The invention changes the compositional parameters of the brazing material layer by defining specific content ranges: Cu 60-95 mass%, Sn 3-30 mass%, Zn 0.1-30 mass%, with no Ag. These parameter changes optimize the brazing material to achieve good TCT characteristics, control TCTC value, and reduce chemical liquid replacement frequency while maintaining bonding strength.
2Strength
If the brazing material layer includes silver (Ag), then bonding is achieved, but durability decreases and TCT characteristics worsen
Solution Approach 1:
The invention extracts silver (Ag) from the brazing material layer to eliminate durability issues. The resulting Ag-free Cu-Sn-Zn brazing material layer achieves both adequate bonding strength and improved durability by avoiding silver-related degradation mechanisms while maintaining effective metallurgical bonding between copper members and ceramic substrates.
Solution Approach 2:
The invention creates a composite brazing material layer using Cu-Sn-Zn combination. This composite material system provides synergistic effects where copper ensures base bonding strength, tin enhances intermetallic formation for strong bonding, and zinc improves wetting and bonding characteristics, collectively achieving both strength and durability without silver.
3Strength
If existing brazing methods with silver are used, then bonding is achieved, but thermal conductivity and TCT characteristics are compromised
Solution Approach 1:
The invention extracts silver (Ag) from the brazing material layer to eliminate thermal cycle test characteristic deterioration. The Ag-free Cu-Sn-Zn composition prevents harmful intermetallic compound formation that degrades under thermal cycling, thereby improving TCT characteristics while maintaining bonding strength through the alternative Cu-Sn-Zn metallurgical system.
Solution Approach 2:
The invention changes the compositional parameters to exclude Ag and optimize Cu, Sn, and Zn content ranges. This parameter optimization ensures the brazing material layer achieves adequate bonding strength while exhibiting superior thermal cycle resistance and thermal conductivity, as the Cu-Sn-Zn system provides better thermal performance without silver-related degradation.
4Strength
If silver-containing brazing material is used, then bonding is achieved, but etchant life decreases and chemical liquid replacement frequency increases
Solution Approach 1:
The invention extracts silver (Ag) from the brazing material layer to extend etchant life. The Ag-free Cu-Sn-Zn composition eliminates silver-related reactions that consume and degrade etching chemicals, thereby significantly extending etchant service life and reducing replacement frequency while maintaining effective bonding through the Cu-Sn-Zn system.
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 improves the thermal cycle test characteristics and durability of ceramic circuit boards by reducing the frequency of chemical liquid replacement, extending the life of the etchant, and allowing for more efficient etching and patterning, while maintaining high bonding strength and thermal conductivity.
Implementation Method 1
a first brazing material etching process of etching an active metal reaction layer included in the brazing material layer by using an etchant that includes one or two selected from hydrogen peroxide and ammonium peroxodisulfate
Implementation Method 2
a first chemical polishing process of chemically polishing an end portion of the brazing material layer exposed by the first brazing material etching process
Implementation Method 3
a bonded body in which a copper member is bonded to at least one surface of a ceramic substrate via a brazing material layer
Data Source
AI summary
According to the embodiment, in a method for manufacturing a ceramic circuit board in which a copper plate is bonded to at least one surface of a ceramic substrate via a brazing material layer, the brazing material layer does not include Ag, but includes Cu, Ti, and one or two of Sn or In, and a ceramic circuit board is prepared in which a portion of the brazing material layer is exposed between the patterned configuration of the copper plate. The method includes a chemical polishing process of chemically polishing the portion of the brazing material layer, and a brazing material etching process of etching the chemically polished portion of the brazing material layer by using an etchant that includes one or two selected from hydrogen peroxide and ammonium peroxodisulfate and has a pH of not more than 6.