MLCC Bonding Strength via Multi-Layer Solder Structure
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Solution Overview
Problem
Multilayer ceramic capacitors (MLCCs) used in automotive applications face challenges with durability against vibrations and deformation, and the bonding between MLCCs and metal frames deteriorates due to thermal and mechanical impacts, leading to potential separation during mounting and high-temperature exposure.
Innovation Solution
The electronic component incorporates a capacitor body with copper-based external electrodes, metal frames connected via a bonding member comprising a tin-based solder layer, a tin-copper alloy solder layer, and a tin-based alloy solder layer, along with a plating layer containing nickel, tin, palladium, silver, or gold, to enhance bonding strength and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-layer solder structure is used to bond the MLCC to the metal frame, then the manufacturing process is simple, but the bonding strength deteriorates under thermal and mechanical impacts
Solution Approach 1:
The bonding member is segmented into multiple layers with different compositions: a first solder layer (Sn-3.0Ag-0.5Cu) contacting the external electrode, a second solder layer (Sn-3.0Ag) in the middle, and a third solder layer (Sn-0.5Cu) contacting the metal frame. Each layer serves a specific function in the bonding interface, distributing stress and improving overall bonding strength under thermal and mechanical impacts.
Solution Approach 2:
The bonding member uses composite material structure with multiple solder layers having different chemical compositions. The combination of Sn-Ag-Cu, Sn-Ag, and Sn-Cu alloys creates a composite bonding system that leverages the advantages of each alloy type: Sn-Ag-Cu for strong bonding to copper electrodes, Sn-Ag for intermediate bonding with high strength, and Sn-Cu for compatibility with the metal frame.
2Reliability
If the MLCC is mounted spaced apart from the board using metal frames, then durability against vibrations is improved, but the bonding portions deteriorate due to thermal and mechanical impacts
Solution Approach 1:
The multi-layer solder structure acts as a cushioning layer between the MLCC and metal frame, absorbing and distributing thermal and mechanical stresses before they reach the bonding interface. The different thermal expansion coefficients of the various solder layers provide stress relief during temperature cycling, preventing deterioration of the bonding portions.
Solution Approach 2:
The invention changes the chemical composition parameters of the solder layers to optimize bonding stability. By carefully selecting the Ag and Cu content in each layer, the bonding interface can withstand thermal expansion differences and mechanical stresses, maintaining stable bonding under varying operating conditions.
3Strength
If a multi-layer bonding structure is used to improve bonding strength, then durability is enhanced, but the manufacturing complexity increases
Solution Approach 1:
The multi-layer solder structure is designed to form self-aligned bonds during the mounting process. The sequential bonding of each solder layer to its respective substrate (external electrode or metal frame) creates a self-organizing structure that reduces the need for complex alignment procedures and manual intervention.
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 improves the bonding strength between the MLCC and metal frames, preventing separation during thermal and mechanical stress, thus enhancing the durability and reliability of the MLCC in automotive applications.
Implementation Method 1
a bonding member disposed between the external electrode and the metal frame. The bonding member includes a tin (Sn)-based solder layer; a tin-copper based alloy solder layer disposed between the tin-based solder layer and the external electrode
Data Source
AI summary
An electronic component includes: a capacitor body; an external electrode disposed on an end of the capacitor body in a first direction and containing copper (Cu) as a main component; a metal frame electrically connected to the external electrode; and a bonding member disposed between the external electrode and the metal frame. The bonding member includes a tin (Sn)-based solder layer; a tin-copper based alloy solder layer disposed between the tin-based solder layer and the external electrode; and a tin-based alloy solder layer disposed between the tin-based solder layer and the metal frame.