Embedded Board Terminal Structure Reduces Resistance
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Solution Overview
Problem
Conventional electronic component-mounting structures experience increased electric resistance and deteriorated conductive characteristics due to the upper-layer film acting as an etching stopper, which can lead to defects and reduced yield in highly integrated fine structures.
Innovation Solution
The electronic component-embedded board features a substrate with terminals having multiple metal layers, where the outermost surface layer has higher electric resistance than the connection layer and is only in contact with the insulating layer, while the wiring layer is connected directly to the connection layer without the outermost surface layer, enhancing close contact properties and reducing electric resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an upper-layer film is added to protect the Al film from laser etching, then the Al film is protected from damage, but the electric resistance in the connecting portion increases and conductive characteristics deteriorate
Solution Approach 1:
The terminal structure is divided into multiple functional layers: the Al film serves as the connection layer for electrical connection, while the upper-layer film (Pd, Pt, or Rh) serves as the protective layer. This segmentation allows each layer to perform its specific function independently, resolving the contradiction between protection and conductivity.
Solution Approach 2:
The patent applies different material properties to different parts of the terminal structure. The Al film provides high electrical conductivity where needed, while the upper-layer film provides protective qualities where required. This local differentiation of material properties resolves the contradiction between protection and conductive characteristics.
2Reliability
If the film thickness of the upper-layer film is increased to enhance protection, then the Al film is better protected, but the electric resistance increases and conductive characteristics further deteriorate
Solution Approach 1:
The patent optimizes the thickness parameter of the upper-layer film to a specific range (1 μm to 10 μm). This parameter optimization ensures sufficient protection while minimizing the impact on electrical resistance, thereby resolving the contradiction between protection effectiveness and conductive characteristics.
3Reliability
If the pad area is increased to improve connection reliability, then the Al film protection is enhanced, but the electric resistance increases and conductive characteristics deteriorate
Solution Approach 1:
The patent differentiates the functional requirements of different regions: the Al film region provides electrical connection with low resistance, while the upper-layer film region provides protection. This local quality differentiation allows the pad area to be optimized for both protection and conductivity simultaneously.
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 prevents the increase of electric resistance in connecting portions and improves conductive characteristics, enhancing the performance and reliability of the electronic component-embedded board by ensuring secure bonding and reduced damage during etching or blast treatments.
Implementation Method 1
the insulating layer is directly bonded to the outermost surface layer
Implementation Method 2
making connection holes such as a via-hole and a hole for a plug in the insulating layer on terminals of the electronic component through laser processing
Data Source
AI summary
An electronic component or the like is mounted on a substrate, and on the electronic component, an insulating layer is provided. Afterward, via-holes V are made in the insulating layer on terminals of the electronic component. Each of the terminals of the electronic component has, for example, a laminate structure of a first metal layer, a second metal layer and a third metal layer. When the via-holes V are formed, part of the third metal layer having a comparatively high electric resistance is removed, and the corresponding portion is connected to a wiring layer including via-conductors. Moreover, the third metal layer excellent in close contact properties with the insulating layer is preferably used.