MLCC Terminal Wettability Structure to Prevent Solder Splash
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Solution Overview
Problem
Conventional multilayer ceramic electronic components with high wettability plated films on metal terminals tend to experience excessive flow of bonding material, leading to solder splash during reflow, which can result in mounting defects.
Innovation Solution
The design incorporates a multilayer ceramic electronic component with a metal terminal featuring a low wettability surface and protruding portions to control the flow of bonding material, preventing excessive flow and splash by using a combination of a Ni-plated layer for solder barrier and a Sn-plated layer for improved wettability, along with a structure that includes notches and openings to facilitate resin flow and strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a plated film with high wettability is provided on the entire surface of the metal terminal, then the bonding property by the bonding material is enhanced, but the bonding material may excessively flow out along the metal terminal causing solder splash
Solution Approach 1:
The patent applies local quality by differentiating the wettability characteristics of different regions on the metal terminal surface. The end surface portion has high wettability for optimal bonding, while the lateral surface portion has low wettability to prevent excessive flow. This spatial differentiation of surface properties resolves the contradiction between achieving strong bonding and preventing solder splash.
Solution Approach 2:
The patent segments the metal terminal surface into distinct functional zones: an end surface portion with high wettability for bonding material attachment and a lateral surface portion with low wettability for controlling material flow. This segmentation allows each region to perform its specific function independently, preventing the harmful effect of solder splash while maintaining reliable bonding.
2Strength
If the bonding material is remelted and the volume of the bonding material expands during reflow, then the bonding strength is enhanced, but a phenomenon of solder splash may occur in which a solder component is ejected from the interface between the exterior material and the metal terminal
Solution Approach 1:
The patent implements preliminary anti-action by pre-configuring the metal terminal surface with differentiated wettability regions before the bonding process. The low wettability lateral surface portion is designed in advance to counteract the tendency of bonding material to flow excessively during reflow and volume expansion, thereby preventing solder splash before it occurs.
Solution Approach 2:
The patent uses local quality by creating spatially varying surface properties on the metal terminal. The end surface maintains high wettability to accommodate bonding material expansion and enhance bonding strength, while the lateral surface has low wettability to contain the bonding material and prevent ejection during reflow heating.
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 configuration effectively reduces or prevents solder splash during reflow, ensuring reliable mounting and enhancing the structural integrity and moisture resistance of the multilayer ceramic electronic components.
Implementation Method 1
a combination of a Ni-plated layer for solder barrier and a Sn-plated layer for improved wettability
Implementation Method 2
a Sn-plated layer for improved wettability
Data Source
AI summary
A multilayer ceramic capacitor includes a multilayer ceramic capacitor main body, metal terminals connected to external electrodes via a bonding material, and an exterior material covering the multilayer ceramic capacitor main body. The metal terminals include bonding surfaces that bond the bonding material and contact surfaces in contact with the exterior material. The contact surfaces include an outermost surface metal film and a lower wettability surface having a lower wettability than that of the outermost surface metal film. A protruding portion is at a boundary portion between a surface of the outermost surface metal film and the lower wettability surface.