Composite Substrate with Rigidity Gradient Bumps
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Solution Overview
Problem
Conventional composite substrates used in inkjet heads tend to deform around bumps during bonding, leading to potential bonding failures between substrates.
Innovation Solution
A composite substrate design where the first substrate has a bump protruding from it, and the second substrate, laminated perpendicularly, has a surface with a bump that partially overlaps the first bump, with the second bump having lower rigidity than the first, to prevent deformation and bonding failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional composite substrates use bumps for bonding substrates together, then electrical connections between substrates are established, but the substrates deform about the bumps during bonding, leading to bonding failure
Solution Approach 1:
The patent applies local quality by creating a rigidity gradient in the bump structure. The first bump has higher rigidity to provide stable electrical connection, while the second bump has lower rigidity to reduce deformation during bonding. This localized differentiation of mechanical properties allows each bump to serve its specific function optimally, resolving the contradiction between connection reliability and substrate stability.
Solution Approach 2:
The patent employs composite materials principle by combining bumps with different rigidity characteristics in a single bonding structure. The first bump (higher rigidity) and second bump (lower rigidity) form a composite system where each material component contributes its specific mechanical properties. This composite approach enables the bonding structure to simultaneously achieve stable electrical connection and reduced deformation.
2Ease of manufacture
If substrates are bonded together using bumps, then electrical connections are established, but bonding failure occurs due to substrate deformation during the bonding process
Solution Approach 1:
The invention differentiates the mechanical properties of bumps at different locations. The first bump maintains higher rigidity to ensure reliable electrical connection, while the second bump uses lower rigidity material to minimize substrate deformation during bonding. This localized property differentiation improves both manufacturability and bonding reliability simultaneously.
Solution Approach 2:
The patent changes the rigidity parameter of the bumps based on their functional requirements. By adjusting the rigidity of the second bump to be lower than the first bump, the bonding process becomes easier to execute without compromising the final connection reliability. This parameter optimization resolves the contradiction between ease of manufacture and bonding success rate.
Data Source
AI summary
A composite substrate has: a first substrate having a first bump protruding therefrom; and a second substrate having a first surface in contact with the first bump, and a second surface opposite to the first surface, the second surface having a second bump protruding therefrom, the second substrate being laminated on the first substrate in a thickness direction perpendicular to the first surface. The first bump and the second bump are partially overlapped with each other as viewed in the thickness direction. The second bump has a rigidity which is lower than a rigidity of the first bump.