Multilayer Ceramic Electronic Part External Electrode Bonding
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Solution Overview
Problem
Existing multilayer ceramic capacitors face issues with poor plating adhesion, electrical properties, and reliability due to issues with external electrode formation methods, including poor bonding between internal and external electrodes, and degradation in insulation resistance and capacitance.
Innovation Solution
A multilayer ceramic electronic part with an external electrode formed from a thermosetting conductive paste containing conductive particles with high melting points and metal powders with melting points of 300°C or less, cured at a temperature range of 80°C to 400°C to enhance bonding properties and plating treatment suitability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a fired-type conductive paste is used to form an external electrode, then the electrode can be formed at elevated temperatures, but glass frit diffuses into the capacitor element causing poor plating adhesion and cracks
Solution Approach 1:
The patent changes the chemical composition parameters of the conductive paste by replacing glass frit with specific inorganic filler materials (such as alumina, silica, or magnesia) that have lower reactivity with the internal electrode. This parameter change allows the paste to be fired at elevated temperatures without causing glass diffusion into the capacitor element, thereby maintaining both the high-temperature processing capability and plating adhesion reliability.
2Reliability
If a thermosetting conductive paste is used at low temperature, then plating adhesion is improved, but metal-to-metal solid-phase diffusion does not progress and bonding is poor
Solution Approach 1:
The patent creates a composite conductive paste material that combines thermosetting resin (for low-curing temperature and good adhesion) with specific inorganic fillers and metal particles. This composite formulation enables the paste to cure at low temperatures while still achieving adequate metal-to-metal diffusion and bonding strength, resolving the contradiction between low-temperature processing and bonding quality.
3Ease of manufacture
If fired-type conductive paste is used, then electrode formation is achieved, but insulation resistance deteriorates due to plating solution infiltration
Solution Approach 1:
The patent modifies the chemical composition of the conductive paste by using inorganic fillers with specific surface properties and lower porosity compared to glass frit. This parameter change creates a more dense and less reactive electrode structure that resists infiltration by plating solutions, thereby maintaining insulation resistance while still allowing for effective electrode formation.
4Temperature
If high-temperature firing is used, then conductive paste is sintered, but glass diffusion causes cracks during solder mounting
Solution Approach 1:
The patent changes the chemical composition of the paste by replacing glass frit with inorganic filler materials that have thermal expansion coefficients matching the ceramic substrate and lower reactivity. This parameter change allows high-temperature firing to proceed without causing glass diffusion and subsequent crack formation during solder mounting processes.
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 achieves excellent bonding and electrical properties, maintaining reliability and capacitance even after heat-cycle testing, while avoiding the defects associated with high-temperature firing and nitrogen atmosphere requirements.
Implementation Method 1
thermosetting the same at a low temperature between 150 to 250° C.
Implementation Method 2
the metal-to-metal solid-phase diffusion of the conductive particles (such as silver powder) in the conductive paste into the internal electrode(s)
Implementation Method 3
the metal-to-metal solid-phase diffusion of the conductive particles (such as silver powder) in the conductive paste into the internal electrode(s)
Implementation Method 4
the surface of an external electrode may be electroplated with nickel in a Watt bath or the like, and thereafter further may be electroplated with solder and/or tin
Data Source
AI summary
The present invention is intended to solve the problem of a conventional thermosetting conductive paste with respect to bonding-property between an internal electrode(s) and an external electrode(s) so as to provide a multilayer ceramic electronic part suitable for its mounting on a substrate and for its plating-treatment. The present invention relates to a multilayer ceramic electronic part, characterized in that it has an external electrode(s) formed from a thermosetting conductive paste comprising conductive particles having a high melting point, metal powder having a melting point of 300° C. or less and a resin(s).