Fingerprint Sensor Package Using Conductive Colloid
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Solution Overview
Problem
Existing semiconductor chip packaging methods face challenges in exposing chip surfaces for applications like fingerprint sensors while protecting against external forces and electrostatic damage, particularly due to the limitations of metal bond wires and press molding processes.
Innovation Solution
The method replaces metal bond wires with a patterned conductive colloid that extends from the chip's periphery along its side wall to connect with the substrate, covered by a non-conductive film and topped with a conductive film for grounding, omitting press molding and enhancing yield and reducing package thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal bond wires are used for electrical connection, then electrical connectivity is achieved, but product yields decrease and package thickness increases
Solution Approach 1:
The patent extracts and removes the metal bond wires from the package structure, replacing them with a conductive colloid that is integrated into the encapsulating material. This elimination of separate wire bonding components simplifies the structure, improves yields by removing wire bonding failure points, and reduces package thickness by integrating the electrical connection function into the encapsulation material itself.
Solution Approach 2:
The patent merges the electrical connection function with the encapsulation function by incorporating conductive colloids into the encapsulating material. The conductive colloid serves dual purposes: providing electrical connectivity between the chip and substrate while simultaneously acting as part of the encapsulation structure that protects the chip. This consolidation eliminates the need for separate wire bonding and reduces overall package complexity and thickness.
2Strength
If press molding is used to form encapsulating colloid, then chip protection is achieved, but device complexity and manufacturing complexity increase
Solution Approach 1:
The patent extracts and removes the press molding process from the manufacturing sequence. Instead of using complex molding operations to form the encapsulating colloid, the invention allows the conductive encapsulating material to be applied and cured in a simpler process, eliminating the need for specialized molding equipment and reducing manufacturing complexity while still achieving adequate chip protection.
Solution Approach 2:
The patent employs a simpler, more disposable-like approach to encapsulation by using conductive colloid that can be applied through less complex means than traditional molding. The encapsulation material serves its protective function without requiring the investment in complex molding tooling and processes, making the manufacturing more flexible and less capital-intensive.
3Adaptability or versatility
If chip surface is exposed for fingerprint sensing, then sensing functionality is enabled, but chip vulnerability to external forces increases
Solution Approach 1:
The patent applies local quality by using a conductive colloid with specific properties in the encapsulation material that provides both protection and electrical functionality. The encapsulating colloid is formulated to be protective against external forces while maintaining the necessary electrical conductivity in specific regions to enable fingerprint sensing functionality through the encapsulated chip surface.
Solution Approach 2:
The patent employs composite materials by creating an encapsulating colloid that combines protective properties with electrical conductivity. The conductive encapsulating material acts as a protective layer against external forces while simultaneously providing electrical pathways that enable the fingerprint sensor to function through the encapsulated surface, thus protecting the chip without compromising sensing capability.
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 approach improves product yields, reduces package thickness, and effectively dissipates static charges, providing protection against external forces and ensuring a stable, durable fingerprint sensor chip package.
Implementation Method 1
the conductive colloid is connected with the ground line on the substrate to dissipate the static charges and protect the chip
Data Source
AI summary
A fingerprint sensor chip package method and the package structure thereof are disclosed. The invention includes: providing a substrate; arranging a sensor chip on the substrate, with an active surface of the sensor chip facing upward; forming a patterned conductive colloid on the sensor chip, wherein the patterned conductive colloid extends from the periphery of the active surface of the sensor chip along the side wall of the sensor and electrically connects with the circuit layer of the substrate; forming a non-conductive film to cover the sensor chip, the patterned conductive colloid and a portion of the substrate; and forming a conductive film on the non-conductive film. The patterned conductive colloid replaces the conventional bond wires to improve the product yield and to omit the molding process. The conductive film is electrically connected with the grounding point/area on the substrate to dissipate the static charges for protecting the chip.