Solid-State Image Pickup Element Electrode Pad Symmetry
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Solution Overview
Problem
The existing solid-state image pickup elements, such as front-illuminated and back-illuminated types, require different mounting members and external circuits due to reversed terminal arrangements, leading to increased costs and preparation times when trying to use a common circuit or mounting member for both.
Innovation Solution
A solid-state image pickup element design featuring first and second electrode pads with interconnections that maintain positional symmetry relative to the center line, allowing for consistent terminal connections regardless of the mounting orientation, eliminating the need for separate external circuits and mounting members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If different mounting members are prepared for front-illuminated and back-illuminated solid-state image pickup elements, then the electrode pads can be properly connected, but the cost and preparatory period increase
Solution Approach 1:
The patent designs the electrode pad arrangement on the semiconductor substrate to be compatible with both front-illuminated and back-illuminated image pickup elements. By positioning the electrode pads at specific locations that remain functionally equivalent regardless of illumination direction, a single mounting member can serve dual purposes, eliminating the need for separate mounting members for each element type and thereby reducing costs while maintaining connection reliability
2Reliability
If different external circuits are prepared for front-illuminated and back-illuminated solid-state image pickup elements, then the terminal arrangements can be matched, but the cost and preparatory period increase
Solution Approach 1:
The patent employs a common external circuit design that can interface with both front-illuminated and back-illuminated image pickup elements. The electrode pad arrangement on the substrate is designed to present the same terminal configuration to the external circuit regardless of the element type, allowing a single external circuit design to serve both element types without modification, thus reducing circuit complexity and preparation requirements
3Ease of manufacture
If the electrode pads are arranged according to the conventional front-illuminated configuration, then the front-illuminated elements can be properly connected, but the back-illuminated elements require reversed terminal arrangements
Solution Approach 1:
The patent strategically positions the electrode pads at asymmetric locations on the semiconductor substrate that happen to be symmetric with respect to the functional requirements of both front- and back-illuminated elements. This asymmetric placement relative to the substrate geometry creates a de facto symmetric interface that works for both element types, allowing conventional manufacturing processes to be used while achieving universal adaptability
Solution Approach 2:
The electrode pad arrangement is designed to be universally compatible with both front-illuminated and back-illuminated image pickup elements. By carefully selecting pad positions that maintain proper electrical connections regardless of which face of the element is illuminated, the same substrate design can be used for both element types, eliminating the need for different mounting configurations
Data Source
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AI summary
A solid-state image pickup element IS1 is provided with a semiconductor substrate 1 having a photosensitive region 3, a plurality of first electrode pads 10 arrayed on a principal face 1 a of the semiconductor substrate 1, a plurality of second electrode pads 12 arrayed in a direction along a direction in which the plurality of first electrode pads 10 are arrayed, on the principal face 1a of the semiconductor substrate 1, and a plurality of interconnections 14 connecting the plurality of first electrode pads 10 and the plurality of second electrode pads 12 in one-to-one correspondence. The plurality of interconnections 14 connect the first and second electrode pads so that each interconnection connects the first electrode pad 10 and the second electrode pad 12 in a positional relation of line symmetry with respect to a center line 1 perpendicular to the array directions of the plurality of first and second electrode pads 10, 12.