Multilayer Electronic Component External Electrode Intermetallic Design
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Solution Overview
Problem
Multilayer ceramic capacitors face reliability issues due to high equivalent series resistance (ESR) and delamination between fired electrode layers and conductive resin layers, especially in high-temperature environments like reflow, where the bonding force is weak and outgassing occurs.
Innovation Solution
A multilayer electronic component design featuring external electrodes with a first intermetallic compound layer of Cu3Sn, a second intermetallic compound layer of Cu6Sn5, and a conductive resin layer with a low melting point metal, metal particles, and a base resin, where the average thickness of the first intermetallic compound layer is between 0.5 to 2.5 μm, enhancing bonding force and electrical connectivity while suppressing delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive resin layers are used in external electrodes to absorb tensile stress and prevent cracks, then reliability is improved, but equivalent series resistance (ESR) increases
Solution Approach 1:
The external electrode uses a composite structure combining a metal layer (Cu3Sn intermetallic compound) with high conductivity and a conductive resin layer (including Cu6Sn5 intermetallic compound and resin) with high stress absorption capability. This composite design allows the metal layer to maintain low ESR while the resin layer provides mechanical protection against tensile stress and thermal expansion, resolving the contradiction between reliability improvement and ESR increase.
2Reliability
If conductive resin layers are used to bond fired electrode layers and plating layers, then mechanical and thermal stress protection is improved, but bonding force decreases due to weak resin bonding
Solution Approach 1:
The external electrode employs a composite structure where a metal layer (Cu3Sn) provides strong metallurgical bonding between the fired electrode layer and plating layer, while the conductive resin layer (Cu6Sn5 + resin) provides mechanical protection. This composite approach overcomes the weak bonding limitation of pure resin by incorporating the high-strength metal intermetallic compound layer.
Solution Approach 2:
The invention controls the thickness of the conductive resin layer to be 5-20 μm and the metal layer to be 0.5-2.5 μm, optimizing the balance between bonding strength and stress protection. By adjusting these dimensional parameters, the design ensures sufficient bonding force while maintaining adequate mechanical protection against thermal and mechanical stress.
3Reliability
If conductive resin layers are used in external electrodes, then crack prevention is improved, but delamination occurs at interfaces due to outgassing in high-temperature environments
Solution Approach 1:
The external electrode uses a composite structure with a metal layer (Cu3Sn) and conductive resin layer (Cu6Sn5 + resin). The metal layer acts as a barrier that prevents gas generated in the resin layer during reflow soldering from reaching the interface between the fired electrode layer and plating layer, thereby preventing delamination while maintaining crack prevention capabilities.
Solution Approach 2:
The metal layer (Cu3Sn intermetallic compound) serves as an intermediary barrier between the conductive resin layer and the fired electrode layer. This intermediate layer blocks the path of gas molecules generated in the resin layer during high-temperature reflow, preventing gas accumulation at the critical interface and eliminating the delamination problem while preserving the crack prevention function of the resin layer.
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 design improves the reliability and reduces ESR of the multilayer electronic component by maintaining stable electrical connectivity and preventing delamination in high-temperature environments, ensuring effective mechanical and thermal stress absorption.
Implementation Method 1
the fired electrode layers and the conductive resin layers are bonded to each other by a bonding force of a resin
Implementation Method 2
a first intermetallic compound layer disposed on the electrode layer and including Cu3Sn; a second intermetallic compound layer disposed on the first intermetallic compound layer and including Cu6Sn5
Implementation Method 3
a technology of using conductive resin layers in external electrodes in order to absorb tensile stress generated in a mechanical or thermal environment to prevent generation of a crack due to the tensile stress
Implementation Method 4
a conductive resin layer disposed on the second intermetallic compound layer and including a conductive connection portion including a low melting point metal
Data Source
AI summary
A multilayer electronic component includes: a body including dielectric layers and internal electrodes disposed alternately with the dielectric layers; and external electrodes disposed on the body, wherein each of the external electrodes includes: an electrode layer connected to the internal electrodes; a first intermetallic compound layer disposed on the electrode layer and including Cu3Sn; a second intermetallic compound layer disposed on the first intermetallic compound layer and including Cu6Sn5; and a conductive resin layer disposed on the second intermetallic compound layer and including a conductive connection portion including a low melting point metal, a plurality of metal particles, and a base resin, and an average thickness of the first intermetallic compound layer is 0.5 to 2.5 μm.