Ceramic Circuit Board Glass Interlayer Adhesion
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Solution Overview
Problem
The increasing heat density in electronic components due to higher integration and reduced size of electronic apparatuses poses a challenge in maintaining the adhesion of metal wiring layers to ceramic sintered bodies, leading to potential peeling issues during operation and thermal cycles.
Innovation Solution
A circuit board design featuring a ceramic sintered body with a metal wiring layer interposed by a glass layer, where the glass layer has a specific interface ratio and includes crystal particles like zinc aluminate, alumina, and zirconia to enhance adhesion strength and heat dissipation, while maintaining mechanical strength and preventing plating adhesion degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the quantity of heat applied to the circuit board is increased due to higher integration and reduced size, then the heat dissipation capability is improved, but the adhesion strength between the metal wiring layer and ceramic sintered body deteriorates
Solution Approach 1:
A glass layer is introduced as an intermediary between the metal wiring layer and the ceramic sintered body. This glass layer acts as a buffer that can accommodate thermal expansion differences and maintain adhesion under high heat conditions, preventing the metal wiring layer from peeling off while allowing effective heat dissipation.
Solution Approach 2:
The circuit board employs a composite structure consisting of multiple layers including the ceramic sintered body, glass layer, and metal wiring layer. This composite material approach allows each layer to contribute its specific properties: the ceramic provides structural support and heat dissipation, the glass layer provides adhesion and thermal buffering, and the metal wiring layer provides electrical conductivity, collectively resolving the contradiction between heat dissipation and adhesion strength.
2Strength
If the metal wiring layer is provided with a glass layer to improve adhesion, then the adhesion strength is improved, but the device structure becomes more complex
Solution Approach 1:
The glass layer is integrated into the existing circuit board structure as an essential component rather than an add-on. It is positioned between the metal wiring layer and ceramic sintered body, merging the functions of adhesion, thermal management, and structural support into a unified multi-layer construction that, while adding a layer, simplifies the overall system by eliminating the need for separate adhesion treatments or complex bonding mechanisms.
3Adaptability or versatility
If the circuit board undergoes repeated on-off operations, then the operational flexibility is improved, but the adhesion strength deteriorates due to thermal cycling
Solution Approach 1:
The glass layer is specifically selected to have thermal expansion properties that bridge the gap between the metal wiring layer and the ceramic sintered body. During repeated on-off operations and thermal cycling, the glass layer expands and contracts in a manner that accommodates the different thermal coefficients of expansion of the adjacent layers, preventing stress concentration and adhesion failure while maintaining operational flexibility.
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 provides a highly reliable circuit board with improved heat dissipation and prolonged durability by maintaining the adhesion of metal wiring layers to the ceramic sintered body, even under repeated thermal cycles, ensuring the electronic apparatus operates effectively for a longer period.
Implementation Method 1
the circuit board has good heat dissipation characteristics
Implementation Method 2
the metal wiring layer is not likely to be peeled away from the ceramic sintered body due to the operation of an electronic component and/or cooling/heating cycles performed by repeated on-off operations thereof
Data Source
Figure 1(a)~1(b)
Figure 2
AI summary
[Object] To provide a highly reliable circuit board which can be used for a long period of time and an electronic apparatus including this circuit board and an electronic component mounted thereon. [Solution] The circuit board includes a ceramic sintered body (11) and a metal wiring layer (13) provided on at least one primary surface (11a) thereof with a glass layer (12) interposed therebetween, and when the cross section of the circuit board perpendicular to the primary surface (11a) of the ceramic sintered body (11) is viewed, the ratio of the length of an interface (15) between the glass layer (12) and the metal wiring layer (13) to a length (12a) of the glass layer (12) in a direction along the primary surface (11a) is 1.25 to 1.80. As a result, good heat dissipation characteristics can be obtained, and the metal wiring layer (13) is not likely to be peeled away from the ceramic sintered body (11) due to operation of an electronic component (21) and/or cooling/heating cycles performed by repeated on-off operations thereof, so that a highly reliable circuit board which can be used for a long period of time can be provided.