Image Pickup Unit Adhesion Strategy for Thermal Deformation Control
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Solution Overview
Problem
Image sensors with packageless structures experience significant deformation in the focus direction due to temperature changes, primarily because the linear expansion coefficient of printed circuit boards is larger than that of ceramic materials, and the rigidity of these boards is lower, making it difficult to maintain adequate adhesion and prevent image blurring.
Innovation Solution
An image pickup unit is designed with an image sensor mounted on a substrate, where the sensor chip is adhered to a holder with an adhesive that contacts the inner surface of the holder's opening and the substrate's surface outside the electronic components, ensuring a larger adhesion area and using specific configurations like tapered surfaces and metal portions to enhance adhesion strength, while the holder is supported by balls to reduce movement resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a packageless structure with printed circuit board is used for image sensor, then mounting flexibility and circuit integration are improved, but deformation in focus direction due to temperature changes increases
Solution Approach 1:
The substrate surface is divided into two functional regions: an electronic component mounting area and an adhesive application area. This segmentation allows the adhesive to be applied to specific regions (outside electronic components) without interfering with component mounting, while still providing sufficient adhesion strength to restrain substrate deformation in the focus direction.
Solution Approach 2:
The adhesive is applied selectively to local regions of the substrate surface rather than uniformly across the entire surface. Specifically, the adhesive contacts the inner surface of the holder opening and the substrate surface outside the electronic component area, creating localized adhesion zones that provide sufficient restraint against thermal deformation while accommodating the packageless structure requirements.
2Strength
If adhesive area is increased to secure adhesion holding strength, then adhesion strength is improved, but available mounting area for electronic components decreases
Solution Approach 1:
The substrate surface is segmented into distinct functional zones: electronic component mounting areas and adhesive application areas. This segmentation enables the adhesive to occupy peripheral regions outside the electronic component footprint, increasing the effective adhesion area without encroaching on the mounting space required for electronic components.
Solution Approach 2:
The adhesive application extends into the peripheral regions of the substrate surface that are not occupied by electronic components. By utilizing the available surface area in these peripheral zones, the adhesive area is maximized without reducing the central mounting area, effectively using spatial dimensionality to resolve the area conflict.
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 effectively restricts image sensor deformation in the focus direction due to temperature changes while maintaining sufficient adhesion strength, thereby reducing image blurs and ensuring reliable operation across varying temperatures.
Implementation Method 1
The image sensor is fixed to the holder with an adhesive that contacts an inner surface and an adhesion area on a second substrate surface
Implementation Method 2
the holder is supported by balls to reduce movement resistance
Data Source
AI summary
An image pickup unit includes an image sensor in which a sensor chip is mounted on a first substrate surface of a substrate having a long side and a short side, and electronic components are mounted on a second substrate surface opposite to the first substrate surface, and a holder having an opening and configured to hold the image sensor. The opening has an inner surface parallel to the short side of the substrate, and the image sensor is fixed to the holder with an adhesive that contacts the inner surface and an adhesion area on the second substrate surface of the substrate that is outside the electronic component.