Laminated Capacitor Mounting Structure for Noise Suppression
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Solution Overview
Problem
High-capacitance laminated ceramic capacitors mounted on wiring substrates generate acoustic noise due to mechanical distortion, which is difficult to control and stabilize due to variations in the amount of joint material used for mounting, leading to inconsistent noise suppression.
Innovation Solution
A laminated capacitor mounted structure with a constricted portion in the joint material between the external electrode and the land on the wiring substrate, where the joint material covers the side surface coating portion and includes a bulged portion spaced away from the body, effectively reducing the propagation of vibrations and noise variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the joint material is allowed to wet upwardly along the external electrodes to ensure proper mounting, then the mechanical connection strength is improved, but the vibration propagation to the wiring substrate increases, causing noise
Solution Approach 1:
The joint material is segmented into two distinct regions: a first joint portion that covers the side surface coating portion of the external electrode, and a second joint portion that covers the land on the wiring substrate. This segmentation creates a clear boundary that prevents vibration propagation while maintaining mounting strength.
Solution Approach 2:
Different regions of the joint material are given different functions: the first joint portion provides mechanical connection and vibration isolation by covering the external electrode's side surface, while the second joint portion provides electrical connection and mechanical support by covering the land. This local differentiation of quality optimizes both noise reduction and mounting strength.
2Object-generated harmful factors
If the amount of joint material is reduced to limit upward wetting and suppress noise, then the vibration propagation is reduced, but it becomes extremely difficult to control the noise level consistently
Solution Approach 1:
The external electrode is pre-formed with a side surface coating portion that extends along the side surface of the capacitor body. This preliminary structural feature guides the joint material to wet upwardly in a controlled manner, forming the first joint portion that acts as a vibration isolation barrier before the joint material reaches the land, thereby ensuring consistent noise suppression.
3Strength
If the joint material covers the entire outer surface of the external electrode to ensure complete coverage, then the mechanical bonding is improved, but the vibration propagation path is extended, increasing noise
Solution Approach 1:
The function of covering the external electrode's side surface is extracted and assigned specifically to the first joint portion, which is limited to covering only the side surface coating portion. This extraction prevents the joint material from forming continuous coverage that would extend vibration propagation paths, while still providing sufficient mechanical bonding through the segmented joint portions.
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
Significantly reduces or prevents variations in noise generation by controlling the propagation path of vibrations, ensuring stable noise suppression and consistent performance across different mounting conditions.
Implementation Method 1
the melted joint material will wet upwardly along the outer surfaces of the external electrodes provided to coat the side surfaces of the body
Implementation Method 2
the above-mentioned vibrations generated in the laminated ceramic capacitor will propagate entirely to the wiring substrate through the joint portions formed by the joint material wetting upwardly
Data Source
AI summary
A mounted structure includes a laminated capacitor, a wiring substrate, and a joint material. The laminated capacitor includes a body with dielectric layers and internal electrode layers alternately stacked, and an external electrode connected to the internal electrode layers. The body includes a side surface coated with a side surface coating portion of the external electrode. The joint material is joined to the side surface coating portion and a land provided on the wiring substrate so as to cover the outer surfaces thereof. The outer end portion of the thickest portion of the joint material covering the side surface coating portion is located farther outside an outer end of the land in a direction perpendicular or substantially perpendicular to a side surface of the body.