Image Sensor Package Thickness Reduction via Internal Conductive Plugs
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Solution Overview
Problem
Conventional image sensor packages have large dimensions due to the need for multiple substrates, which makes them prone to conductive layer damage during fabrication, reducing fabrication yield.
Innovation Solution
An image sensor package design that eliminates the need for a separate carrying substrate by integrating a second substrate as a covering plate, with a conductive plug connecting the bonding pad internally, reducing package thickness and protecting the conductive layer from external damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional image sensor package uses multiple substrates (chip, covering plate, and carrying substrate), then the package provides structural support and electrical connections, but the package dimensions become large
Solution Approach 1:
The patent merges the chip substrate and covering plate into a single integrated substrate structure. The sensor device is formed on the first substrate, and the second substrate serves as both a covering plate and structural support, eliminating the need for a separate third carrying substrate. This consolidation reduces the overall package dimensions while maintaining structural integrity and electrical connection capabilities.
2Reliability
If the conductive layer is formed on the exterior sidewall of the carrying substrate, then electrical connections are established, but the conductive layer is easily damaged during fabrication
Solution Approach 1:
The patent transitions the conductive layer from an exterior sidewall configuration to an internal configuration. The conductive layer is formed on the lower surface of the first substrate and extends through holes in both substrates to reach the bonding pad on the upper surface. This internal routing through the substrate thickness dimension protects the conductive layer from external mechanical damage during fabrication while maintaining electrical connectivity.
3Ease of operation
If a separate carrying substrate is used to support the sensor device, then the sensor device is properly positioned and connected, but the package thickness increases
Solution Approach 1:
The patent combines the functions of the chip substrate, covering plate, and carrying substrate into a two-substrate integrated structure. The first substrate supports the sensor device and bonding pad, while the second substrate serves as both a covering plate and structural carrier. This merging eliminates the need for a separate third carrying substrate, thereby reducing package thickness while maintaining proper sensor device positioning and support.
Data Source
AI summary
The invention provides an image sensor package and method for fabricating the same. The image sensor package comprises a first substrate comprising a sensor device thereon and a hole therein. A bonding pad comprising a first opening is formed on an upper surface of the first substrate. A second substrate comprising a spacer element with a second opening therein is disposed on the first substrate. A conductive plug is formed in the hole and passes through the first and second openings to the second substrate to electrically contact with the bonding pad. A conductive layer is formed on a lower surface of the first substrate and electrically connects to the conductive plug. A solder ball is formed on the conductive layer and electrically connects to the bonding pad by the conductive plug. The image sensor package further comprises a second substrate bonding to the first substrate. The image sensor package is relatively less thick, thus, the dimensions thereof are relatively reduced.