Bump Metal Layer Bonding for Uniform Solder Thickness
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Solution Overview
Problem
The significant size difference between the contact points of microscopic electronic units and substrates leads to uneven thickness of solder bonds, resulting in insufficient mechanical strength and reduced reliability of electronic devices.
Innovation Solution
The design includes a substrate with bump metal layers and a bonding unit with specific ratios of widths and areas of bump metal layers, ensuring that the solder and conductive pad sizes are proportionally matched to the bump metal layers, thereby controlling the thickness of the bonding member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder is used to bond the electronic unit and the substrate, then the electronic unit can be connected to the substrate, but the significant size difference between contact points causes considerable change in bonding thickness, resulting in insufficient mechanical strength
Solution Approach 1:
The patent changes the geometric parameters of the bump metal layers by establishing a specific width ratio (0.3-0.9) between the smaller bump metal layer on the electronic unit and the larger bump metal layer on the substrate. This parameter adjustment ensures that the solder bonding member maintains uniform thickness during bonding, preventing mechanical strength degradation while preserving bonding reliability.
2Volume of moving object
If the size of electronic unit contact point is reduced, then the electronic unit can be miniaturized, but the size difference with substrate contact point increases, causing uneven bonding thickness
Solution Approach 1:
The patent applies local quality by creating asymmetric bump metal layer structures where the substrate has larger bump metal layers and the electronic unit has smaller bump metal layers, with their widths maintaining a specific ratio. This local structural differentiation compensates for the size difference between components, ensuring uniform solder thickness distribution across all bonding interfaces even when the electronic unit is miniaturized.
Data Source
AI summary
An electronic device includes a substrate, an electronic unit, and a bonding unit. The substrate includes a first bump metal layer and a second bump metal layer arranged in a first direction. The electronic unit includes a third bump metal layer overlapped with the first bump metal layer and a fourth bump metal layer overlapped with the second bump metal layer. The bonding unit includes a first bonding member disposed between the first bump metal layer and the third bump metal layer and a second bonding member disposed between the second bump metal layer and the fourth bump metal layer. In the first direction, a ratio of a width of the third bump metal layer to a width of the first bump metal layer is greater than or equal to 0.3 and less than or equal to 0.9.