Multilayer Ceramic Capacitor Thermal Stress and Creepage Design
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Solution Overview
Problem
Multilayer ceramic capacitors in high-voltage inverter circuits face issues with creeping discharge, thermal runaway, and cracking due to deflection stress from thermal expansion, which existing solutions like film capacitors and metal terminals with high resistivity alloys either fail to adequately address or introduce additional heat generation and size inefficiencies.
Innovation Solution
A multilayer ceramic electronic component design featuring a laminate structure with metal terminals and terminal blocks, where the metal terminals have a low coefficient of linear expansion to minimize thermal stress and heat generation, and the component is miniaturized by orienting the ceramic bodies to reduce mounting area and enhance heat radiation properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If film capacitors are used to ensure creepage distance, then creeping discharge is reduced, but heat-resistant temperature is low causing thermal runaway at high operating temperatures
Solution Approach 1:
The patent uses a composite structure combining ceramic bodies with metal terminals and resin encapsulation. The ceramic provides high voltage resistance and thermal stability, the metal terminals provide low resistivity for heat dissipation, and the resin provides creepage protection. This composite approach resolves the contradiction by integrating materials that collectively provide both creepage distance and high-temperature resistance.
2Reliability
If metal terminals with high resistivity alloys are used to absorb deflection stress, then cracking is reduced, but heat generation increases due to current flow
Solution Approach 1:
The patent applies different material properties to different parts of the terminal structure. The terminal bodies use low-resistivity metals (copper, aluminum, or their alloys) for optimal electrical conductivity and heat dissipation. The terminal blocks use resin materials with appropriate mechanical properties for stress absorption. This local differentiation resolves the contradiction by assigning electrical performance requirements to the terminal bodies and mechanical stress absorption to the terminal blocks.
3Area of stationary object
If multilayer ceramic capacitors are miniaturized by reducing thickness dimension, then mounting area is reduced, but creeping discharge risk increases
Solution Approach 1:
The patent compensates for reduced creepage distance in the thickness dimension by utilizing the width dimension. The resin encapsulation extends along the width direction to provide adequate creepage paths, while the thickness is minimized for compact mounting. This dimensional redistribution resolves the contradiction by maintaining creepage protection through spatial reconfiguration rather than increasing overall size.
4Loss of energy
If ceramic bodies are oriented with thickness dimension less than width dimension, then heat radiation is improved, but mounting configuration becomes more constrained
Solution Approach 1:
The patent employs asymmetric orientation of the ceramic bodies where the thickness dimension is deliberately made less than the width dimension. This asymmetric configuration optimizes the surface area-to-volume ratio for heat dissipation while the terminal block design provides flexible mounting options that accommodate this orientation. The asymmetry resolves the contradiction by prioritizing thermal performance while maintaining mounting feasibility through adaptive terminal block design.
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 reduces the risk of creeping discharge, thermal runaway, and cracking while allowing for miniaturization and improved heat radiation, thus enhancing the reliability and efficiency of high-voltage inverter circuits.
Implementation Method 1
the metal terminals have a low coefficient of linear expansion to minimize thermal stress and heat generation
Implementation Method 2
a creeping discharge, that is, a discharge that occurs between outer electrodes, more easily occurs in electronic components like multilayer ceramic capacitors
Implementation Method 3
the component is miniaturized by orienting the ceramic bodies to reduce mounting area and enhance heat radiation properties
Data Source
AI summary
A multilayer ceramic electronic component includes multilayer ceramic electronic component bodies each including a laminate and first and second outer electrodes respectively disposed on two end surfaces of the laminate, first and second metal terminals respectively connected to the first and second outer electrodes, and first and second terminal blocks respectively connected to the first and second metal terminals. A thickness dimension of each multilayer ceramic electronic component body in a height direction is less than a width dimension of the multilayer ceramic electronic component body in a width direction. Each multilayer ceramic electronic component body is disposed such that a first or second side surface faces a mounting surface. The first and second metal terminals are respectively disposed astride the first and second outer electrodes of the multilayer ceramic electronic component bodies.