Multilayer Ceramic Device Tin Plating Thickness Asymmetry
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Solution Overview
Problem
In multilayer ceramic electronic devices, the variation in thickness of plating films affects solder wettability and connection reliability, leading to issues with external electrodes rising unevenly during soldering, which compromises the connection between the electrodes and the substrate.
Innovation Solution
A multilayer ceramic electronic device with external electrodes having a tin plating film as the outermost layer, where the thickness of the tin plating film on the end surfaces is smaller than on the side surfaces, and optionally including nickel and copper plating films with varying thicknesses to enhance thermal conductivity and solder wettability, ensuring balanced solder distribution and improved connection reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the thickness of the tin plating film is made uniform across all surfaces, then the manufacturing process is simple, but the solder wettability becomes unbalanced causing external electrodes to rise unevenly during soldering
Solution Approach 1:
The patent applies different thicknesses of tin plating film to different surfaces of the external electrodes. Specifically, the side surfaces have a first thickness while the end surfaces have a second thickness that is different from the first. This local differentiation ensures that solder rises evenly during reflow soldering, preventing the external electrodes from rising upward and improving connection reliability between the electrodes and the substrate.
2Reliability
If the tin plating film thickness on end surfaces is increased, then solder wettability on end surfaces improves, but solder rises excessively on one side causing the external electrode to rise upward
Solution Approach 1:
The patent intentionally creates an asymmetric thickness distribution of the tin plating film on the end surfaces. Rather than making the thickness uniform or simply increasing it, the patent specifies that the second thickness on the end surfaces should be within a specific range (0.5-5 μm) and different from the first thickness on the side surfaces. This asymmetric design balances the solder wettability across different surfaces, preventing excessive solder rise on any single side and maintaining the proper position of the external electrodes.
3Volume of moving object
If electronic parts are miniaturized, then device size is reduced, but the thickness difference in plating films becomes more significant causing external electrodes to rise during soldering
Solution Approach 1:
The patent addresses the miniaturization challenge by optimizing the thickness parameters of the tin plating film. For smaller devices, the patent specifies that the thickness of the tin plating film on the end surfaces should be within 0.5-5 μm, which is a carefully controlled parameter range. This parameter optimization ensures that even in miniaturized devices, the solder wettability is sufficient to prevent electrode rise, while the overall device size is reduced. The patent thus maintains connection reliability through precise parameter control despite device miniaturization.
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 prevents uneven solder rise and enhances the connection reliability of external electrodes by promoting solder wetting on the side surfaces while maintaining balanced solder distribution, ensuring secure mounting and improved thermal properties.
Implementation Method 1
the reactivity between the solder and the tin plating film on the side surfaces improves, and the solder rises along the tin plating film on the side surfaces earlier than on the end surface due to wetting
Data Source
AI summary
A multilayer ceramic electronic device includes a pair of external electrodes respectively covering end surfaces of a main body, wherein a height of the multilayer ceramic electronic device that includes the pair of eternal electrodes is greater than 0.80 times and less than 1.25 times as much as the lessor of a width dimension of the electronic device and a length dimension of the electronic device, and wherein each of the pair of external electrodes includes a tin plating film as an outermost layer, and a thickness of the tin plating film on the end surface of the main body is smaller than a thickness of the tin plating film on side surfaces of the main body.