Substrate-Free Image Sensor Packaging With Encapsulant Vias
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Solution Overview
Problem
Current image sensors have a large package size due to the necessity of a substrate for electrical connection and thick encapsulants to cover conducting wires, making it difficult to reduce the overall volume of the image sensor module.
Innovation Solution
The image sensor design eliminates the need for a substrate by using an image sensing chip with exposed contact pads, outer-side encapsulant vias with conducting layers, interior and exterior wire redistribution layers, and a transparent cover plate, allowing direct electrical connection to an external circuit board without wire bonding, thereby reducing the package size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a substrate is used for electrical connection of the image sensing chip, then electrical connection is achieved, but the package thickness increases
Solution Approach 1:
The invention extracts and eliminates the substrate from the traditional image sensor structure. The image sensing chip is directly mounted on the circuit board without requiring a separate substrate, thereby removing the thickness contribution of the substrate while maintaining electrical connection functionality through alternative means (direct mounting and wire bonding).
Solution Approach 2:
The invention changes the dimensional arrangement by flipping the image sensing chip upside down and mounting it directly on the circuit board. This dimensional reconfiguration allows the chip to be positioned in a different spatial orientation, eliminating the need for a substrate and reducing overall package thickness.
2Reliability
If thick encapsulant is used to cover conducting wires, then wire protection is achieved, but the package size increases
Solution Approach 1:
The invention extracts and removes the unnecessary portion of the encapsulant. By eliminating the substrate, the encapsulant no longer needs to extend underneath it, allowing the encapsulant thickness to be reduced while still adequately protecting the conducting wires and chip mounting area.
3Strength
If substrate and thick encapsulant are used, then structural support and protection are achieved, but manufacturing cost increases
Solution Approach 1:
The invention extracts and eliminates the substrate from the structure. The circuit board itself provides the necessary structural support, making the separate substrate unnecessary. This reduction in component count directly lowers material costs and assembly complexity.
Solution Approach 2:
The circuit board assumes multiple functions: it provides structural support, serves as the mounting platform for the image sensing chip, and acts as the electrical connection interface. This multi-functionality eliminates the need for a dedicated substrate, reducing component count and manufacturing cost.
4Reliability
If traditional substrate-based structure is used, then electrical connection is achieved, but overall module volume increases
Solution Approach 1:
The invention extracts and removes the substrate from the system. The image sensing chip is directly mounted on the circuit board, eliminating the intermediate substrate layer and reducing the overall volume of the image sensor module while maintaining all necessary electrical connection functions.
Data Source
AI summary
An image sensor includes an image sensing chip, an encapsulant, a plurality of outer-side encapsulant vias, an interior wire redistribution layer and an exterior wire redistribution layer. The encapsulant wraps around the image sensing chip, the outer-side encapsulant vias penetrate the encapsulant, and the interior wire redistribution layer is formed on a top surface of the encapsulant, wherein the image sensing chip is electrically connected to the exterior wire redistribution layer through the interior wire redistribution layer and the outer-side encapsulant vias, and then further through the conducting terminals on the exterior wire redistribution layer to connect to the outside. The exterior wire redistribution layer is directly formed underneath the image sensing chip without using a substrate. Since the electrical connection is realized through the outer-side encapsulant vias, the thicknesses of the encapsulant and the size of the packaged image sensor can be reduced.