Thick-Film Electrode Structure for Solder Diffusion Blocking
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Solution Overview
Problem
The surface mounting technique for electronic components faces challenges in achieving sufficient reliability due to metal diffusion into pad and land electrodes, leading to increased contact resistance and potential detachment under vibration, which compromises the strength and reliability of the bonding.
Innovation Solution
An electronic component design featuring a base material with an insulating film and thick-film electrodes, where a diffusion prevention layer with a first portion covering the electrode body and a second portion extending parallel to the base material surface prevents metal diffusion from conductive bonding materials, thereby enhancing bonding strength and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If surface mounting technique is used to bond pad electrodes to land electrodes, then bonding is achieved, but metal diffusion occurs leading to increased contact resistance and reduced reliability
Solution Approach 1:
A diffusion prevention layer is introduced as an intermediary between the thick-film electrode and the bonding interface. This layer acts as a barrier that prevents metal diffusion from the bonding material into the electrode, thereby resolving the contradiction between achieving bonding and preventing harmful metal diffusion.
Solution Approach 2:
The diffusion prevention layer is segmented into multiple portions: a first portion covering the body portion of the thick-film electrode and a second portion extending parallel to the main surface. This segmentation allows the layer to effectively block diffusion paths while maintaining electrode functionality.
2Object-generated harmful factors
If diffusion prevention layer covers only the body portion, then diffusion is partially prevented, but bonding surface area is reduced
Solution Approach 1:
The diffusion prevention layer extends in two dimensions: vertically covering the body portion and horizontally extending parallel to the main surface. This dimensional extension allows the layer to prevent diffusion while simultaneously enlarging the bonding surface area, resolving the contradiction between diffusion prevention and bonding area.
Solution Approach 2:
Different portions of the diffusion prevention layer serve different functions: the first portion primarily prevents diffusion, while the second portion extending parallel to the main surface enlarges the bonding surface. This local differentiation resolves the contradiction by optimizing each region for its specific purpose.
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 solution effectively suppresses metal diffusion into the thick-film electrodes, maintaining bonding strength and reliability by enlarging the bonding surface and preventing metal component penetration, thus ensuring improved adhesion and reduced contact resistance.
Implementation Method 1
a diffusion prevention layer covering the body portion, wherein the diffusion prevention layer has a first portion directly covering a surface of the body portion and a second portion directly covering the main surface
Data Source
AI summary
In the electronic component, the second portion of the diffusion prevention layer extends parallel to the main surface of the base material. When the electronic component is surface-mounted on the mounting substrate, the conductive bonding material such as solder is interposed between the electrodes of the electronic component and the land electrodes of the mounting substrate. In the case that the bonding surface between the diffusion prevention layer and the substrate is wide, it is difficult for the metal component of the bonding material to reach the body portion of the electrodes through the bonding surface. Therefore, a situation in which metal component of the bonding material diffuse into the body portion is suppressed, and a decrease in strength of the electrodes due to the diffusion is suppressed.