Metal Matrix Composite Connectors for Ceramic Component Cracking
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Solution Overview
Problem
Ceramic electronic components on printed circuits face reliability issues due to mechanical stress and thermal expansion mismatches, leading to cracking and reduced capacitance, especially in severe environments like turbojet engines, and current solutions either limit component size or use intermediate connectors that can cause heating and thermo-mechanical stress.
Innovation Solution
A printed circuit design using metal matrix composite connectors with thermal expansion coefficients close to ceramics, providing high thermal conductivity to manage heat dissipation and reduce mechanical stress, allowing for larger ceramic components to be connected in parallel without overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If intermediate connectors made of FeNiCo alloy are used to fix ceramic components to the support, then the coefficient of thermal expansion mismatch is reduced, but heating of the ceramic components occurs and thermal conductivity is insufficient
Solution Approach 1:
The patent applies composite materials by using a metal matrix composite connector consisting of a copper matrix reinforced with carbon particles (Cu-C composite). This composite structure combines the low thermal expansion coefficient of carbon (close to ceramic) with the high thermal conductivity of copper, simultaneously resolving both the crack resistance and heating issues. The carbon reinforcement provides thermal expansion matching while the copper matrix provides heat dissipation.
Solution Approach 2:
The patent changes the material parameters of the connector by selecting a Cu-C composite with specific properties: thermal expansion coefficient between 5-15 ppm/K (matching ceramic) and thermal conductivity greater than 100 W/mK (for heat dissipation). This parameter optimization allows the connector to simultaneously prevent cracking and reduce heating.
2Reliability
If the size of ceramic components is limited to reduce mechanical stress, then cracking is reduced, but the capacity of the components is also limited
Solution Approach 1:
The Cu-C composite connector enables larger ceramic components by providing both mechanical support and effective heat dissipation. The high thermal conductivity prevents the heating that would cause thermal stress and cracking in larger components, while the matched thermal expansion coefficient ensures mechanical compatibility.
3Quantity of substance
If multiple ceramic components are connected in parallel via FeNiCo connectors, then the component capacity increases, but the component furthest from the support heats up more and cracking risk increases
Solution Approach 1:
The Cu-C composite connector's high thermal conductivity (greater than 100 W/mK) enables efficient heat dissipation across all connected components, including those furthest from the support. This uniform heat dissipation prevents the temperature gradient that would otherwise cause cracking in distant components.
Solution Approach 2:
The connector serves multiple functions simultaneously: mechanical support, thermal expansion matching, and heat dissipation. This multi-functionality allows parallel connection of multiple components without the temperature distribution problems that limit conventional single-function connectors.
4Reliability
If connectors with coefficient of thermal expansion close to ceramic are used, then cracking is reduced, but thermal conductivity is insufficient and heating occurs
Solution Approach 1:
The Cu-C composite connector resolves this contradiction by combining materials with complementary properties: carbon provides thermal expansion matching (5-15 ppm/K close to ceramic) while copper provides high thermal conductivity (>100 W/mK). This composite structure simultaneously achieves crack resistance and effective heat dissipation.
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 prevents cracking and overheating of ceramic components, enabling a larger number of components to be connected in parallel while maintaining mechanical integrity and reducing thermo-mechanical stresses, thus enhancing the reliability and lifespan of the assembly.
Implementation Method 1
a connector made of composite material with a metal matrix has a high thermal conductivity, and it therefore allows good evacuation of the heat from the ceramic component or components
Implementation Method 2
it has a coefficient of thermal expansion close to that of ceramics and consequently it makes it possible to limit the risks of cracks in the ceramic component
Data Source
Figure 1~3
Figure 4~5
AI summary
The invention relates to a printed circuit comprising a substrate (1) onto which at least one ceramic component (2, 3, 4) is attached so as to enable the heat produced by the ceramic component (2, 3, 4) to be discharged and to prevent cracks in the ceramic component (2, 3, 4) and in the substrate (1). To this end, the ceramic component (2, 3, 4) is attached onto the substrate (1) by means of two connectors (5, 6) made of metal matrix composite material. Said two connectors further preferably have incisions so as to enable the mechanical stresses exerted in the substrate to be carried over into the connectors.