Clad Frame Terminal Structure for MLCC Solder Crack Prevention
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Solution Overview
Problem
Conventional electronic components mounted directly on a board experience heat transmission and deformation, leading to increased equivalent series resistance (ESR), heat generation, and solder cracking due to mismatched thermal expansion coefficients between the metal frame and board-mounted solder.
Innovation Solution
A multilayered capacitor design with a frame terminal composed of a clad structure, where the frame terminal has a higher thermal expansion coefficient than the capacitor body but lower than the conductive bonding portions, combined with a clad structure of different materials to reduce stress and prevent solder cracking while maintaining high electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal frame is bonded to the sides of electronic components to secure a distance between the component and board, then heat and deformation are absorbed, but the equivalent series resistance increases and solder cracking may occur
Solution Approach 1:
The frame terminal is constructed as a composite structure comprising a base portion made of a first material and a surface portion made of a second material with different properties. This composite structure allows the frame terminal to simultaneously achieve low equivalent series resistance (through the conductive base material) and appropriate thermal expansion characteristics (through the surface material), thereby resolving the contradiction between electrical performance and thermal stress management.
Solution Approach 2:
Different portions of the frame terminal are assigned different material properties: the base portion uses a material optimized for electrical conductivity to minimize ESR, while the surface portion uses a material with specific thermal expansion characteristics to match the PCB and reduce solder cracking. This local differentiation of material properties allows simultaneous optimization of electrical and thermal performance.
2Reliability
If a metal frame is bonded to protect electronic components, then distance is secured between component and board, but crack defects occur in solder bonding portion due to excessive difference in coefficient of thermal expansion
Solution Approach 1:
The invention carefully selects and controls the coefficient of thermal expansion parameter of the frame terminal materials. The base portion material is chosen to provide structural stability, while the surface portion material is specifically selected to have a CTE that matches the PCB, thereby minimizing thermal expansion mismatch and preventing solder cracking during thermal cycling while maintaining protective functionality.
Solution Approach 2:
By combining materials with different CTE characteristics in a composite frame terminal structure, the invention achieves an overall CTE that is optimized for both mechanical protection and thermal compatibility with the PCB, preventing solder cracking while maintaining the protective distance between component and board.
3Device complexity
If conventional electronic components are mounted directly on a board, then simple mounting is achieved, but heat and deformation are directly transmitted to the component
Solution Approach 1:
The frame terminal acts as an intermediary element between the electronic component and the PCB. It provides mechanical support and electrical connection while simultaneously serving as a thermal buffer that absorbs and dissipates heat, preventing direct heat transmission to the component and reducing deformation effects from the PCB.
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 suppresses ESR increase, prevents solder cracking, and enhances electrical conductivity and terminal strength, ensuring reliability under high-temperature and low-temperature variations.
Implementation Method 1
A coefficient of thermal expansion of the frame terminal is greater than that of the capacitor body and is smaller than that of the first conductive bonding portion
Implementation Method 2
The clad may be obtained by overlapping a metal plate including a first material and a metal plate including a second material, and then mechanically bonding the metal plate by rolling
Data Source
AI summary
An electronic component includes a multilayered capacitor including a capacitor body and an external electrode disposed on one surface of the capacitor body, a frame terminal mounting the multilayered capacitor on a board, and a conductive bonding portion disposed between the board and the frame terminal. The frame terminal includes a base portion including a first material and a surface portion including a second material, and a coefficient of thermal expansion of the frame terminal is greater than that of the capacitor body and is smaller than that of the conductive bonding portion.