Composite Substrate Bump Design for Inkjet Head Bonding
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Solution Overview
Problem
Conventional composite substrates used in inkjet heads face issues with bending, deformation, or breakage of the second substrate due to the load applied during bonding, which can damage the substrate and affect the performance of the inkjet head.
Innovation Solution
A composite substrate design that includes a first substrate, a second substrate, electric contacts, first bumps with a conducting film, and second bumps with a smaller dimension, arranged to distribute the load and prevent direct contact with the insulating layer, thereby reducing the risk of deformation or breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If bump parts are used to bond the first substrate and second substrate together, then the two substrates can be securely connected, but the load applied through the bump parts can cause the second substrate to bend, deform, or break
Solution Approach 1:
The bump parts are divided into two distinct types: first bump parts for electrical connections and second bump parts for mechanical support and sealing. This segmentation allows each type to be optimized for its specific function, with the second bump parts being smaller to reduce load concentration on the second substrate while maintaining bonding strength and sealing effectiveness.
Solution Approach 2:
Different regions of the composite substrate have different bump part characteristics. The first bump parts have larger dimensions for electrical connectivity, while the second bump parts have smaller dimensions specifically at locations separated from electrical contacts. This local quality differentiation ensures that areas requiring sealing and mechanical support use smaller bumps that apply less concentrated load, preventing substrate deformation while maintaining bonding integrity.
2Reliability
If the second bump part is positioned separated from electrical contacts, then it can provide mechanical support and sealing without causing electrical interference, but it may reduce the overall bonding strength
Solution Approach 1:
The second bump parts serve multiple functions simultaneously: they provide mechanical support for bonding, create sealing between substrates, and maintain electrical insulation by being positioned away from electrical contacts. This multi-functionality allows the composite substrate to achieve reliable electrical insulation while maintaining adequate bonding strength through the distributed support of multiple second bump parts.
Solution Approach 2:
The second bump parts are pre-positioned at locations separated from electrical contacts before bonding occurs. This preliminary positioning ensures that during the bonding process, these bump parts bear the mechanical load and provide sealing without interfering with electrical contact formation, thereby maintaining both electrical insulation and bonding strength from the outset.
Data Source
AI summary
A composite substrate includes: a first substrate; a second substrate; an electric contact; a first bump; and a second bump. The first substrate has a first surface. The first substrate has a thickness defining a thickness direction. The second substrate has a second surface. The second surface faces the first surface with a predetermined gap therebetween in the thickness direction. The electric contact is positioned at the second surface. The first bump includes: a core; and a conducting film. The core is provided at the first surface and has a convex shape protruding in the thickness direction. The conducting film covers a part of the core and is in contact with the electric contact. The second bump is provided at the first surface and has a convex shape protruding in the thickness direction. The second bump has a dimension in the thickness direction smaller than that of the first bump.