Bonding Ceramic and Cu Members Using Active Metal Brazing
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Solution Overview
Problem
The existing methods for bonding ceramic substrates to Cu foils result in the formation of thick, rigid intermetallic compound layers, which decrease the bonding rate between the ceramic substrate and the circuit layer, leading to insufficient bonding.
Innovation Solution
A method involving the use of a Ti paste and a Cu-P-Sn-Ni brazing filler material with 3-10% P, where the Ti paste is applied close to the Cu member and the Cu-P-Sn-Ni brazing filler material is applied close to the ceramic member, allowing for heating in a vacuum furnace under pressure to form an intermetallic compound that prevents the formation of a rigid layer at the bonded interface, enhancing the bonding rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Cu-Mg-Ti brazing filler material is used to bond Cu foil to ceramic substrate, then bonding between ceramic substrate and circuit layer is achieved, but thick rigid intermetallic compound layer is formed at the bonded interface, decreasing bonding rate
Solution Approach 1:
The patent changes the chemical composition parameters of the brazing filler material by replacing Mg and Ti with P, Sn, and Ni elements. This composition modification fundamentally alters the bonding mechanism, preventing the formation of thick rigid intermetallic compounds while achieving reliable bonding between Cu foil and ceramic substrate at lower temperatures.
Solution Approach 2:
The patent uses a composite brazing filler material system comprising Cu-P-Sn-Ni alloy. This composite material combines multiple elements with complementary functions: P for low melting point and wetting, Sn for ductility and bonding, and Ni for strength. The synergistic effect of these elements prevents rigid intermetallic formation while ensuring strong bonding.
2Reliability
If conventional brazing methods are used to bond ceramic substrate to Cu member, then bonding is achieved, but high temperature heating is required, increasing thermal load on ceramic substrate
Solution Approach 1:
The patent modifies the physical and chemical parameters of the brazing system by using Cu-P-Sn-Ni filler material with lower melting point than conventional Cu-Mg-Ti alloys. This enables the bonding process to be conducted at reduced temperatures, lowering thermal load on the ceramic substrate while maintaining bonding strength through optimized composition and vacuum pressure conditions.
Solution Approach 2:
The patent employs vacuum atmosphere during the bonding process to prevent oxidation of the Cu-P-Sn-Ni brazing filler material and the Cu foil surface. This inert environment ensures proper wetting and bonding at lower temperatures without requiring high temperature to overcome oxidative barriers, thereby reducing thermal load on the ceramic substrate.
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 bonding rate between the ceramic and Cu members, allowing for reliable bonding at lower temperatures, reducing thermal load on the ceramic substrate and preventing the formation of rigid intermetallic compounds, thus enhancing the reliability and efficiency of the bonding process.
Implementation Method 1
a Cu-P-Sn-Ni brazing filler material containing 3 mass% to 10 mass% of P is interposed between the Cu member and the ceramic member
Implementation Method 2
an intermetallic compound containing P is formed, and P is drawn into the intermetallic compound
Implementation Method 3
the ceramic member and the Cu member which are laminated are placed into and heated in a vacuum heating furnace while being pressurized
Implementation Method 4
a Ti paste and a Cu-P-Sn-Ni brazing filler material containing 3 mass% to 10 mass% of P are interposed between the Cu member and the ceramic member
Data Source
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AI summary
A method of producing a bonded body is disclosed in which a ceramic member made of ceramics and a Cu member made of Cu or a Cu alloy are bonded to each other, the method including: a laminating step of laminating the ceramic member and the Cu member in a state where a Cu-P-based brazing filler material containing 3 mass% to 10 mass% of P and an active metal material are interposed therebetween; and a heating step of heating the ceramic member and the Cu member which are laminated.