Image Pickup Unit With Variable-Angle Recess for Resin Protection
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Solution Overview
Problem
Existing image pickup units in endoscopes face challenges in achieving a small diameter while ensuring adequate resin protection for the stacked device, leading to reliability issues due to insufficient or excessive resin volumes, which affect performance.
Innovation Solution
A three-dimensional wiring board with a recess having varying inclination angles for the wall surfaces, combined with controlled resin injection based on the increasing area of the resin observed from the principal surface, ensures appropriate resin volume is injected, enhancing reliability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resin is injected into the gap between the recess and the stacked device to protect the stacked device, then reliability is improved, but when the volume of resin is large, the light receiving surface is covered by the resin, degrading performance
Solution Approach 1:
The recess is designed with different inclination angles in different regions: the lower region has a larger inclination angle to accommodate excess resin without covering the light receiving surface, while the upper region has a smaller inclination angle to provide adequate resin volume for protection. This local variation in geometric properties resolves the contradiction between needing sufficient resin volume and preventing resin from covering the light receiving surface.
2Reliability
If the volume of resin injected is increased to improve protection of the stacked device, then reliability is improved, but the diameter of the image pickup unit increases, reducing invasiveness
Solution Approach 1:
Instead of increasing resin volume uniformly in all directions (which would increase diameter), the design utilizes the vertical dimension by creating a recess with varying inclination angles. The lower region with larger inclination angle allows resin to be contained vertically without expanding the horizontal diameter, thus maintaining small invasiveness while providing adequate protection volume.
3Length of moving object
If the volume of resin injected is decreased to reduce diameter of the image pickup unit, then invasiveness is reduced, but protection of the stacked device is insufficient, reducing reliability
Solution Approach 1:
The upper region of the recess has a smaller inclination angle that creates a wider horizontal space, allowing adequate resin volume to be contained within a small diameter. This local geometric modification enables sufficient protection without increasing the overall diameter of the image pickup unit.
Data Source
AI summary
An image pickup unit includes: a three-dimensional wiring board including a recess on a first principal surface, in which a wall surface of the recess has an inclination angle of an upper region that is smaller than an inclination angle of a lower region; a stacked device disposed in the recess, the stacked device including an optical system and an image pickup device; and resin disposed in a gap between the recess and the stacked device.