Flip Chip Ball Grid Array Image Sensor Package
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Solution Overview
Problem
The use of bond wires in imaging systems limits the space on the surfaces of image sensor dies and package substrates due to the formation of bond pads, making it challenging to create efficient image sensor chip-scale packages.
Innovation Solution
The implementation of a flip chip configuration using through-silicon vias and conductive bumps to couple the image sensor die to the package substrate, eliminating the need for additional bond pads and allowing for a more compact design by forming an image sensor chip-scale package with a solder ball grid array.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bond wires are used to couple the image sensor die to the substrate, then electrical connection is achieved, but space on the surfaces is limited due to bond pad formation
Solution Approach 1:
The patent transitions from surface-level bond pad connections to three-dimensional through-silicon via connections. Conductive bumps extend vertically through the die, allowing electrical connection without occupying additional surface area, thus resolving the contradiction between reliable electrical connection and available surface space.
Solution Approach 2:
The patent introduces conductive bumps as an intermediary element between the image sensor die and substrate. These bumps serve as the connecting medium, replacing the need for large bond pads while achieving reliable electrical connection through the die thickness.
2Reliability
If bond pads are formed on the surfaces for wire bonding, then electrical connection is established, but the design becomes less compact
Solution Approach 1:
The invention moves the connection interface from the two-dimensional surface plane to the three-dimensional vertical dimension through through-silicon vias and conductive bumps. This eliminates the need for surface bond pads and redistribution layers, achieving a more compact package design while maintaining electrical connection reliability.
Solution Approach 2:
The patent extracts and eliminates the bond pad structure from the surface, replacing it with conductive bumps that extend through the die. This removal of unnecessary surface elements simplifies the overall package design and improves compactness.
3Area of stationary object
If through-silicon vias and conductive bumps are used instead of bond wires, then surface space is conserved, but manufacturing complexity increases
Solution Approach 1:
The manufacturing process is segmented into distinct steps: forming through-silicon vias, depositing conductive material to create bumps, and mounting the die. This segmentation allows each step to be optimized independently, making the complex process more manageable and suitable for automated manufacturing.
Data Source
AI summary
An imaging system may include an integrated circuit package that includes an image sensor die mounted in a flip chip configuration to a package substrate. The image sensor die may be a backside illumination sensor die. The image sensor die may include an imaging device structure formed over a carrier layer. Through-silicon vias formed in the carrier layer may couple imaging device circuitry in the imaging device structure to conductive bumps on the carrier layer that are coupled to metal interconnects. A ball grid array may be formed on a surface of the package substrate that may be coupled to the conductive bumps. A glass lid may be attached to the image sensor die using attachment structures such that an air gap is formed between the glass lid and the image sensor die. Package sealing material may be deposited between the image sensor die and the package substrate.