MLCC Terminal Wettability Zoning to Prevent Solder Splash
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Solution Overview
Problem
Conventional multilayer ceramic electronic components with high-wettability plating films on metal terminals tend to experience excessive bonding material flow, leading to solder splash during reflow mounting due to the expansion of the bonding material, which can result in mounting defects.
Innovation Solution
The multilayer ceramic electronic components incorporate metal terminals with a bonding surface and a contact surface featuring a lower-wettability intermetallic compound layer, which reduces excessive bonding material flow and prevents solder splash by controlling the wettability and flow of the soldering material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a plating 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 excessively flows out along the metal terminal causing solder splash
Solution Approach 1:
The patent applies different surface treatments to different regions of the metal terminal. The bonding surface is treated to have high wettability for strong bonding, while the contact surface with the exterior material is treated to have low wettability to prevent excessive bonding material flow. This local differentiation of surface properties resolves the contradiction between achieving strong bonding and preventing solder splash.
Solution Approach 2:
The metal terminal surface is segmented into distinct functional zones: a bonding surface for bonding material attachment and a contact surface for exterior material contact. This segmentation allows each zone to have optimized wettability characteristics independent of the other, enabling strong bonding without excessive material flow.
2Strength
If the bonding material is remelted and the volume expands during reflow, then the bonding strength is improved, but solder splash occurs due to excessive flow
Solution Approach 1:
The low-wettability treatment on the contact surface is applied in advance to prevent the bonding material from flowing excessively during reflow. This preliminary preventive measure counteracts the tendency of the bonding material to flow outward when heated and expanded, thereby preventing solder splash while allowing the bonding to strengthen.
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 design effectively prevents excessive bonding material flow and solder splash, ensuring reliable mounting and reducing the occurrence of defects in multilayer ceramic electronic components.
Implementation Method 1
The first contact surface in contact with the exterior material includes a surface of a first outermost surface metal film and a surface of a first intermetallic compound having a wettability lower than the surface of the first outermost surface metal film
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 that covers 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 a surface of an outermost surface plating film and a surface of an intermetallic compound having a wettability lower than that of the surface of the outermost surface plating film.