Dual Adhesive Bonding for Image Sensor Alignment
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Solution Overview
Problem
Existing imaging apparatus manufacturing methods face challenges in achieving reliable and cost-effective bonding of imaging optical systems to image sensors, with issues related to alignment accuracy, bonding strength, and manufacturing efficiency.
Innovation Solution
The use of a dual bonding member approach, where ultraviolet-cured first bonding members provide temporary alignment and positioning, followed by thermosetting second bonding members for final bonding, ensures strong and accurate attachment of the imaging optical system to the image sensor substrate, reducing manufacturing costs and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single adhesive is used for bonding the substrate to the holding member, then the bonding process is simple, but the alignment accuracy and bonding strength are insufficient
Solution Approach 1:
The bonding process is divided into two distinct stages using two different bonding members: a first bonding member (UV-curable adhesive) for initial alignment and temporary bonding, and a second bonding member (thermosetting adhesive) for final strong bonding. This segmentation allows each bonding member to be optimized for its specific function, achieving high alignment accuracy and strong bonding strength without excessive overall complexity.
Solution Approach 2:
The first bonding member is applied and cured before the second bonding member, creating a preliminary bond that establishes accurate alignment. This preliminary action allows the substrate to be precisely positioned and fixed relative to the holding member before the final bonding process, ensuring high alignment accuracy in the completed assembly.
2Strength
If a strong bonding member is used from the beginning, then bonding strength is high, but alignment accuracy deteriorates due to shrinkage
Solution Approach 1:
The bonding process is divided into two stages: first using a UV-curable bonding member that exhibits minimal shrinkage during curing to establish accurate alignment, then using a thermosetting bonding member that provides strong bonding strength. This segmentation allows the alignment-critical first stage to use a low-shrinkage adhesive, while the strength-critical second stage uses a high-strength adhesive, resolving the contradiction between strength and alignment accuracy.
Solution Approach 2:
The first bonding member is applied and cured preliminarily to establish accurate alignment before the second bonding member is applied. This preliminary alignment step ensures that when the strong second bonding member is later applied and cured, the substrate is already in the correct position, preventing alignment degradation despite the strong bonding forces involved.
3Manufacturing precision
If multiple bonding members are used, then bonding strength and alignment accuracy are improved, but manufacturing time increases
Solution Approach 1:
The first bonding member uses UV light curing instead of thermal curing, which dramatically reduces the curing time from typical thermal cure cycles (minutes to hours) to a few seconds. This substitution of the curing mechanism allows the two-stage bonding process to complete quickly, offsetting the time cost of using multiple bonding members and maintaining efficient manufacturing.
Solution Approach 2:
The bonding process is designed so that the first bonding member is applied and cured, then the second bonding member is applied and cured in a continuous sequence without interruption or removal of components. This continuous progression through the bonding stages minimizes idle time and ensures that the manufacturing time increase from using two bonding members is kept to a minimum.
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 method enhances alignment accuracy, maintains positional integrity, and reduces manufacturing time and costs by utilizing adhesives with controlled shrinkage ratios and strengths, ensuring robust bonding and improved imaging apparatus reliability.
Implementation Method 1
applying a first bonding member between a substrate bonding face of a holding member and at least a part of a first face of a substrate, on which an image sensor is mounted; curing the first bonding member
Implementation Method 2
applying a second bonding member across at least a part of a second face of the substrate, that is the opposite to the first face of the substrate, and the substrate bonding face; curing the second bonding member
Data Source
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AI summary
Provided is an imaging apparatus having: an imaging optical system including at least one optical element; an image sensor configured to capture an object image formed by the imaging optical system; a substrate on which an image sensor is mounted; a holding member configured to hold the imaging optical system, the holding member including a substrate bonding face that is bonded to the substrate; a first bonding member configured to bond at least a part of a first face of the substrate, that faces the substrate bonding face, to the substrate bonding face; and a second bonding member configured to bond at least a part of a second face of the substrate, that is opposite to the first face of the substrate, to the substrate bonding face.