Multilayer Capacitor Electrode Interface for Low ESR and Crack Prevention
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Solution Overview
Problem
Multilayer ceramic capacitors face issues with high Equivalent Series Resistance (ESR) and cracking due to mechanical and thermal stress, which affects their reliability and electrical performance.
Innovation Solution
Incorporating an intermetallic compound layer, specifically nickel-copper (Ni—Cu), between the internal and external electrodes, with a conductive resin layer containing metal particles like copper, nickel, silver, or tin-coated copper, to enhance connectivity and reduce ESR while preventing cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive resin layer is applied to the external electrode to absorb tensile stress and prevent cracking, then reliability is improved, but Equivalent Series Resistance (ESR) increases
Solution Approach 1:
An intermetallic compound layer is introduced as an intermediary between the internal electrode and external electrode. This layer serves as a mediator that provides both mechanical stress absorption (preventing cracking) and maintains low electrical resistance (low ESR), resolving the contradiction between reliability improvement and energy loss increase.
Solution Approach 2:
The invention changes the material parameters at the electrode interface by forming an intermetallic compound layer with specific composition and thickness ratios. By controlling the thickness ratio of the intermetallic compound layer to be 5-50 times thinner than the internal electrode, the electrical resistance is optimized while maintaining sufficient mechanical protection against cracking.
2Loss of energy
If the thickness of the intermetallic compound layer is increased to improve connectivity, then ESR decreases, but mechanical flexibility and stress absorption capability deteriorate
Solution Approach 1:
The invention optimizes the thickness parameter of the intermetallic compound layer by establishing a specific ratio range (5-50 times thinner than the internal electrode). This parameter optimization achieves the best balance between electrical conductivity (low ESR) and mechanical flexibility (stress absorption), preventing both excessive resistance and mechanical brittleness.
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 lowers ESR and prevents cracking, ensuring stable electrical performance and reliability of the multilayer capacitors by optimizing the connectivity between internal and external electrodes.
Implementation Method 1
a total number of the intermetallic compound layer may be more than or equal to 55% and less than 100% of a total number of the plurality of internal electrodes
Implementation Method 2
a technique of applying a conductive resin layer to an external electrode by absorbing tensile stress generated in mechanical or thermal environments is provided to prevent the occurrence of cracks caused by stress
Implementation Method 3
Such a conductive resin layer serves to electrically and mechanically bond a sintered electrode layer and a plating layer of the external electrode of the multilayer capacitor
Implementation Method 4
An average depth of portions of the external electrode that diffuse to the plurality of internal electrodes, on connection portions between the plurality of internal electrodes and the external electrode, may be 30 μm or more
Data Source
AI summary
A multilayer capacitor and a board having the same mounted thereon are provided. The multilayer capacitor includes a capacitor body including a plurality of dielectric layers and a plurality of internal electrodes alternately disposed with each of the plurality of dielectric layers interposed therebetween, and an external electrode disposed on the capacitor body to be connected to the internal electrode. At least one intermetallic compound layer is disposed in a region in which the plurality of internal electrodes and the external electrode are connected, and a total number of the at least one intermetallic compound layer is more than or equal to 55% and less than 100% of a total number of the plurality of internal electrodes.