Asymmetric Bump Design for Compact Image Pickup Apparatus
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Solution Overview
Problem
Existing solid-state image pickup apparatuses face challenges in preventing inner leads from short-circuiting with the image pickup device due to their small diameter and right-angle bend, which can lead to contact with the device's corner portions.
Innovation Solution
The image pickup apparatus features a flexible wiring board with inner leads that are compression-bonded to bumps on the image pickup device, where the leads are bent with a recess-shaped distal end and a projection-shaped rear end, allowing them to be parallel to the device's side face, thus avoiding contact with the device's corners, and the bumps are shaped to have a lower height on the light receiving portion side than the side face side, preventing short-circuiting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the inner lead is bent substantially at a right angle to reduce the apparatus diameter, then the apparatus diameter is reduced, but the inner lead may come into contact with and short-circuit with the image pickup device
Solution Approach 1:
The bump structure is made asymmetric with different heights on the light receiving portion side and side face side. The inner lead is bent asymmetrically to follow the bump contour, creating an asymmetric path that maintains safe distance from the image pickup device while achieving compact diameter.
Solution Approach 2:
The inner lead bending is extended into the vertical dimension by following the asymmetric bump profile. Instead of a simple planar right-angle bend, the lead incorporates vertical height variations that match the bump's asymmetric topology, adding a height dimension to the bending path.
2Reliability
If the bump height on the light receiving portion side is reduced to prevent short-circuiting, then short-circuit risk is reduced, but the bonding strength between the inner lead and bump may be compromised
Solution Approach 1:
The bump exhibits local quality variation with different heights at different locations. The light receiving portion side has lower height for safety, while the side face side maintains higher height for bonding strength. This localized height differentiation allows simultaneous achievement of both safety and strength requirements.
Solution Approach 2:
The bump structure employs asymmetric height design where the height on the light receiving portion side differs from the height on the side face side. This asymmetry enables the bump to provide both short-circuit prevention (lower height side) and adequate bonding strength (higher height side).
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 allows for a smaller diameter image pickup apparatus, minimizing invasiveness and preventing short-circuiting, while maintaining a stable bond between the leads and the device, ensuring reliable operation.
Implementation Method 1
the distal end portion being compression-bonded to any one of the plurality of bumps
Implementation Method 2
the bending portion of each of the inner leads is plastically transformed according to a shape of top faces of the bumps
Data Source
AI summary
An image pickup apparatus is configured with an image pickup device on which a plurality of bumps are arranged in line on an outer circumferential portion of a light receiving surface; and a flexible wiring board including a plurality of inner leads each of which is configured with a distal end portion, a bending portion and a rear end portion, the distal end portion being compression-bonded to a bump, and the rear end portion being arranged parallel to a side face of the image pickup device with the bending portion interposed between the distal end portion and the rear end portion. A height of a light receiving portion side of the bumps is lower than a height of a side face side; and each of the inner leads is plastically transformed according to a shape of a top face of the bumps.