Ceramic Component Electrode Curvature for Thermal Stress Relief
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Solution Overview
Problem
The degree of contact between an embedded electronic component and a wiring substrate often deteriorates due to differences in thermal expansion coefficients, leading to stress and potential separation between the component and the substrate.
Innovation Solution
A multilayer ceramic electronic component design featuring specific triangular areas defined by hypothetical straight lines on its outer electrodes, which are inclined at 45° and extend across the component's surfaces, reduces stress concentration and enhances contact durability by ensuring a larger equivalent radius of curvature, thereby minimizing contact deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If an electronic component is embedded in a wiring substrate to reduce footprint, then the footprint is reduced, but the degree of contact between the component and substrate deteriorates due to thermal expansion differences
Solution Approach 1:
The outer electrodes are designed with a specific curved surface geometry where the surface is tangent to imaginary spherical surfaces. This curvature design increases the equivalent radius of curvature at contact points, distributing thermal expansion stress more evenly and preventing contact deterioration while maintaining the embedded configuration.
Solution Approach 2:
The invention changes the geometric parameters of the outer electrodes, specifically controlling the curvature radius and surface orientation. By optimizing the equivalent radius of curvature to be 0.05mm or more, the electrode structure can accommodate thermal expansion differences between the ceramic component and wiring substrate, maintaining reliable contact while embedded.
2Ease of manufacture
If the outer electrode surface is made flat for simple manufacturing, then manufacturing is easier, but stress concentration occurs during thermal expansion causing contact deterioration
Solution Approach 1:
Instead of flat surfaces, the outer electrodes incorporate controlled curvature by being tangent to imaginary spherical surfaces. This geometric feature distributes stress during thermal cycling and prevents concentration at sharp edges or flat interfaces, while remaining compatible with standard manufacturing processes like co-firing.
Solution Approach 2:
The curved surface design anticipates thermal expansion stresses by providing a geometry that naturally distributes these forces before they cause damage. The increased equivalent radius of curvature acts as a pre-designed stress distribution mechanism that prevents contact deterioration during subsequent thermal cycling.
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 design effectively reduces stress between the ceramic electronic component and the wiring substrate, preventing contact deterioration and maintaining a stable interface even under temperature changes, as demonstrated by reduced maximum stress values and absence of cracks in the component.
Implementation Method 1
The degree of contact between an electronic component that has been embedded in a wiring substrate and the wiring substrate may sometimes deteriorate due to differences in thermal expansion coefficients
Data Source
AI summary
An electronic component has dimensions (length×width×thickness) of about 0.6 mm to about 1.0 mm×about 0.3 mm to about 0.5 mm×about 0.07 mm to about 0.15 mm. An area of a triangle defined by a first hypothetical straight line being in contact with the top of a portion of an outer electrode positioned on a first main surface at a center in the width direction and extending in the length direction, a second hypothetical straight line being in contact with the top of a portion of the outer electrode positioned on the first end surface at the center in the width direction and extending in the thickness direction, and a third hypothetical straight line being in contact with the outer electrode at the center in the width direction and being inclined at about 45° with respect to the first and second hypothetical straight lines is about 450 μm2 or larger.