Flip-Chip Substrate Wiring Patterns for Uniform Solder Bumps
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Solution Overview
Problem
The existing flip-chip mounting substrates with bonding pads in an area array arrangement face challenges in increasing density and reducing inter-bonding-pad pitch, leading to variations in solder bump shape and connection strength due to differences in bonding pad and lead wire areas.
Innovation Solution
A flip-chip mounting substrate design where bonding pads and lead wires are exposed from an insulating layer or solder resist, with varying shapes and equal areas to ensure uniform solder distribution and shape consistency, and a combination of wiring patterns with different dimensions to reduce inter-bonding-pad pitches in both directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If bonding pads are arranged in an area array with reduced inter-bonding-pad pitch to increase density, then the density of bonding pads is improved, but variation in solder bump shape and connection strength occurs due to differences in bonding pad and lead wire areas
Solution Approach 1:
The patent applies local quality by making different parts of the wiring pattern (bonding pad vs. lead wire) have different shapes but equal areas. The bonding pad has a first shape while the lead wire has a second shape different from the first, yet both are designed to have substantially equal areas to ensure uniform solder distribution across all bonding locations.
Solution Approach 2:
The patent changes the area parameter of both the bonding pad and lead wire to be substantially equal, while maintaining different shape parameters. This parameter adjustment ensures that solder bumps formed on both structures have consistent dimensions and properties, resolving the variation issue while maintaining high density.
2Productivity
If inter-bonding-pad pitch is reduced to achieve narrower pitch connections, then connection density is improved, but solder distribution uniformity deteriorates due to unequal areas of bonding pads and lead wires
Solution Approach 1:
The patent applies local quality by making different parts of the wiring pattern (bonding pad vs. lead wire) have different shapes but equal areas. The bonding pad has a first shape while the lead wire has a second shape different from the first, yet both are designed to have substantially equal areas to ensure uniform solder distribution across all bonding locations.
Solution Approach 2:
The patent changes the area parameter of both the bonding pad and lead wire to be substantially equal, while maintaining different shape parameters. This parameter adjustment ensures that solder bumps formed on both structures have consistent dimensions and properties, resolving the variation issue while maintaining high density.
Data Source
AI summary
It is a flip-chip mounting substrate according to the invention has a wiring pattern in which bonding pads and predetermined parts of lead wires continuously extending from the bonding pads are exposed from an insulating layer or a solder resist. In the flip-chip mounting substrate, exposed parts of the wiring pattern are formed in to a plurality of different shapes. The exposed parts are formed so that the areas of the bonding pads are substantially equal to one another, and that the total areas of predetermined parts of the lead wires continuously extending from the bonding pads are substantially equal to one another.