Convex Electrode Arrangement for Image Pickup Apparatus Stress Reduction
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Solution Overview
Problem
The bonding process of image pickup devices with convex electrodes and wiring boards in CSP-type image pickup apparatuses often results in defective products due to stress applied to the light receiving section, leading to reduced yield and reliability, particularly in back-side illumination devices with thin image pickup devices.
Innovation Solution
The convex electrodes are arranged in a rotationally symmetric pattern around the optical axis, avoiding the light receiving section facing region to distribute stress uniformly and reduce defects, with additional dummy electrodes used to enhance stress equalization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If convex electrodes are arranged on the opposing surface in a conventional pattern, then electrical connection is achieved, but stress is applied to the light receiving section causing defects
Solution Approach 1:
The patent extracts the convex electrodes from the light receiving section facing region and relocates them to the peripheral region of the opposing surface. This separation removes the harmful stress application to the light receiving section while maintaining the electrical connection function through the relocated electrodes.
Solution Approach 2:
The patent applies local quality by creating different functional zones on the opposing surface: the peripheral region houses the convex electrodes for electrical connection, while the central light receiving section facing region remains free of electrodes to avoid stress. This spatial differentiation optimizes both connection reliability and light receiving performance.
2Ease of manufacture
If convex electrodes are placed on the opposing surface, then electrical bonding is enabled, but manufacturing defects increase due to stress on thin image pickup devices
Solution Approach 1:
The patent extracts the convex electrodes from the vulnerable light receiving section area and places them in the peripheral region. This extraction maintains the bonding capability while removing the source of manufacturing defects caused by stress on thin image pickup devices.
Solution Approach 2:
The patent employs asymmetric arrangement by positioning convex electrodes specifically in the peripheral region rather than distributing them uniformly across the opposing surface. This asymmetric placement enables bonding while avoiding the symmetric stress distribution that would affect the central light receiving section.
3Reliability
If convex electrodes are arranged in a lattice pattern, then electrical connection is achieved, but stress distribution is uneven causing reduced yield
Solution Approach 1:
The patent extracts the convex electrodes from the central region and relocates them to the periphery, fundamentally changing the stress distribution pattern from concentrated to dispersed, thereby achieving more uniform stress distribution while maintaining electrical connection.
Solution Approach 2:
The patent transitions the electrode arrangement from a two-dimensional lattice pattern to a perimeter-based linear arrangement along the peripheral region. This dimensional change in placement strategy redistributes stress along the edges rather than concentrating it in the center, improving stress distribution uniformity.
Data Source
AI summary
An image pickup apparatus includes: an image pickup device including: a light receiving section configured to receive light entering from a light receiving surface; and a plurality of convex electrodes disposed on an opposing surface; an optical system configured to condense the light on the light receiving section; and a wiring board including a plurality of bonded terminals on a main surface, the plurality of bonded terminals respectively bonded to the plurality of convex electrodes, wherein the plurality of convex electrodes are not arranged in a light receiving section facing region that faces a region provided with the light receiving section.