Multilayer Ceramic Capacitor Bump Adhesion via Composite Paste
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Solution Overview
Problem
Conventional multilayer ceramic capacitors experience low adhesive strength between the capacitor main body and bumps, leading to separation issues.
Innovation Solution
The use of bumps composed of tin regions, resin regions, and metal regions including copper and silver, with a bump-producing paste that includes copper covered with silver, epoxy resin, and a solvent, but no curing agent, to enhance the adhesive strength between the capacitor main body and bumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If bumps are formed on the capacitor main body to cover outer electrodes, then acoustic noise is reduced, but adhesive strength between the capacitor main body and bumps becomes low
Solution Approach 1:
The bump-producing paste uses a composite material system comprising metal powder (copper, nickel, or palladium), resin (epoxy resin with specific glass transition temperature), and solvent. This composite formulation creates bumps with optimized adhesive strength to the capacitor main body while maintaining the noise reduction function. The specific combination of materials and their proportions ensures both strong bonding and acoustic noise suppression.
Solution Approach 2:
The invention specifies precise parameter ranges for the bump-producing paste components: metal powder content (30-70 wt%), resin type (epoxy resin with Tg of 50-150°C), and solvent content. By controlling these parameters, the paste achieves optimal adhesion to the capacitor main body after drying and firing, preventing bump separation while maintaining the noise reduction effect.
2Ease of manufacture
If conventional bump-producing paste is used, then bumps can be formed on the capacitor main body, but the adhesive strength is low causing bump separation
Solution Approach 1:
The invention optimizes the paste formulation with specific parameter ranges: metal powder (30-70 wt%), epoxy resin with controlled molecular weight and glass transition temperature (50-150°C), and controlled solvent content. These parameter adjustments ensure the paste maintains proper viscosity for application while achieving strong adhesion to the capacitor main body after processing, eliminating bump separation issues.
Solution Approach 2:
The bump-producing paste is designed with localized material properties: the resin component provides adhesion specifically at the interface between the bump and capacitor main body, while the metal powder provides structural integrity and electrical conductivity. This localized functional differentiation ensures strong bonding without compromising other bump properties.
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 improved adhesive strength between the bumps and the capacitor main body reduces the risk of separation and enhances the fixing strength, thereby reducing acoustic noise and maintaining effective electrical connectivity.
Implementation Method 1
improve an adhesive strength between a capacitor main body and bumps
Implementation Method 2
bump-producing paste that includes copper covered with silver, epoxy resin, and a solvent
Data Source
AI summary
A multilayer ceramic capacitor includes a multilayer body including dielectric layers and internal electrode layers alternately laminated on one another, outer electrode layers on end surfaces of the multilayer body at opposite ends in a longitudinal direction and covering end surface sides of principal surfaces of the multilayer body at opposite ends in a laminating direction and end surface sides of side surfaces at opposite ends with respect to a width direction, and bumps on the end surface sides of one of the principal surfaces of the multilayer body such that the outer electrode layers covering the one principal surface are sandwiched between the bumps and the one principal surface. Each of the bumps includes tin regions, metal regions including copper, and silver regions including silver.