Capacitor Recesses and Rounded Corners for Wiring Substrate Adhesion
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Solution Overview
Problem
Current methods for incorporating capacitors in wiring substrates face challenges such as low adhesion properties, reliability issues due to thermal stress, warpage, and inefficiencies in forming plated films, particularly with the electrolytic plating method, which affects the manufacturing process and electrical connectivity.
Innovation Solution
The capacitor design features recesses on its side faces to enhance adhesion with resin fillers, chamfered or rounded corners to reduce warpage, and a manufacturing method that includes forming notched holes and external electrode patterns to facilitate efficient electrolytic plating, allowing for improved adhesion and reduced manufacturing time and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the capacitor is incorporated in the opening of a core substrate with resin filler, then the capacitor is fixed in the core substrate, but the adhesion properties between the capacitor and resin filler are low due to the ceramic side faces
Solution Approach 1:
Rounded portions are formed at the corner portions of the capacitor body to replace sharp corners with curved surfaces. This curvature modification improves adhesion between the capacitor and resin filler by eliminating stress concentration points, while the rounding is performed on the sintered capacitor body to maintain manufacturing efficiency
Solution Approach 2:
The corner portions of the capacitor body are selectively modified with rounded portions, while the rest of the capacitor body maintains its original flat surface. This localized modification improves adhesion only where needed (at corners) without affecting the overall manufacturing process or requiring complete surface restructuring
2Reliability
If rounded portions are formed by polishing method after sintering, then adhesion properties are improved, but the dielectric layers are worked requiring long working time-periods and high costs
Solution Approach 1:
Rounded portions are formed at the corner portions of the capacitor body to replace sharp corners with curved surfaces. This curvature modification improves adhesion between the capacitor and resin filler by eliminating stress concentration points, while the rounding is performed on the sintered capacitor body to maintain manufacturing efficiency
Solution Approach 2:
The radius of curvature of the rounded portions is controlled within a specific range (0.01 to 0.1 mm) to achieve optimal balance between adhesion improvement and manufacturing efficiency. This parameter optimization ensures sufficient rounding for stress distribution while minimizing the material removal and processing time required
3Device complexity
If the capacitor is incorporated in the wiring substrate, then the process number is reduced and degree of freedom for other electronic parts is increased, but thermal stress is concentrated in the resin filler or insulating layers causing cracks
Solution Approach 1:
Rounded portions are formed at the corner portions of the capacitor body to replace sharp corners with curved surfaces. This curvature modification improves adhesion between the capacitor and resin filler by eliminating stress concentration points, while the rounding is performed on the sintered capacitor body to maintain manufacturing efficiency
Solution Approach 2:
The rounded portions are formed in advance on the capacitor body before incorporation into the wiring substrate. This pre-forming of rounded corners provides beforehand cushioning against thermal stress by eliminating sharp corners that would act as stress concentration points during subsequent thermal cycling, preventing cracks in the resin filler and insulating layers
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 enhances the adhesion and reliability of capacitors in wiring substrates, reduces warpage, and enables efficient electrolytic plating of external electrode layers, improving electrical connectivity and manufacturing efficiency.
Implementation Method 1
the adhesion properties between the capacitor and the resin filler are so low that the reliability cannot be sufficiently retained
Implementation Method 2
These plated films are formed at present by an electroless plating method. However, it takes a long time to form the plated films by the electroless plating method
Data Source
AI summary
A wiring substrate in which a capacitor is provided, the capacitor comprising a capacitor body including a plurality of dielectric layers and internal electrode layers provided between the different dielectric layers, wherein said capacitor body has, in at least one side face of said capacitor body, recesses extending in a thickness direction of said capacitor body from at least one of a first principal face of said capacitor body and a second principal face positioned on the side opposite to the first principal face.