Ultrasonic Fingerprint Sensor Package Stepped Control Chip
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Solution Overview
Problem
Current ultrasonic fingerprint sensor packages face challenges in reducing size and cost due to bonding wire connections and through-silicon-vias technology.
Innovation Solution
A package design featuring a substrate with first connecting electrodes, a control chip with stepped surfaces and redistribution layer connections, bonding wires, and an ultrasonic transducer, where the second connecting electrodes are higher than the third, reducing package volume and cost through wire bonding, and using adhesive layers for secure bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If through-silicon-vias technology is used to connect the control chip to the substrate, then the package size is reduced, but the manufacturing cost increases
Solution Approach 1:
The control chip is divided into different height levels with a stepped upper surface structure. The peripheral lower surface is lower than the central upper surface, allowing different regions to serve different functions. This segmentation enables the use of wire bonding for peripheral connections while maintaining a compact overall structure, thus reducing package size without requiring expensive through-silicon-vias technology throughout the entire chip.
Solution Approach 2:
Different connection methods are applied to different regions of the control chip. The peripheral region uses wire bonding technology for cost-effective connections, while the central region maintains higher elevation for other functional requirements. This localized application of connection technologies optimizes both cost and size considerations for each specific region of the chip.
2Ease of manufacture
If bonding wires are used to connect the control chip to the substrate, then the manufacturing cost is reduced, but the package size increases
Solution Approach 1:
The control chip employs a stepped upper surface with variations in height (vertical dimension). The peripheral lower surface is positioned at a lower elevation than the central upper surface. This vertical dimensionality allows bonding wires to connect to the peripheral region without increasing the horizontal footprint of the package, thus maintaining compact size while using cost-effective wire bonding technology.
3Reliability
If the control chip thickness is increased through wire bonding, then the connection reliability is improved, but the package volume increases
Solution Approach 1:
The control chip's upper surface is segmented into different height levels. The peripheral lower surface provides connection points for bonding wires at a lower elevation, while the central upper surface maintains higher elevation for other functions. This segmentation allows reliable wire bonding connections without requiring increased overall chip thickness, thus maintaining compact package volume while ensuring connection reliability.
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
The design achieves a smaller package size and lower bonding costs while maintaining effective ultrasonic fingerprint detection, with the redistribution layer technique reducing thickness and adhesive layers ensuring secure connections.
Implementation Method 1
an ultrasonic transducer positioned on the control chip... configured to transmit ultrasound and detect the ultrasound reflected back thereto
Implementation Method 2
the bonding wires are configured to bond the first connecting electrodes to the third connecting electrodes by a wire bonding technique
Implementation Method 3
the first adhesive layer is configured to connect the top surface of the substrate with the lower surface of the chip
Data Source
AI summary
The present disclosure discloses a package for an ultrasonic fingerprint sensor comprising: a substrate comprising a top surface and a plurality of first connecting electrodes formed on the top surface; a control chip arranged on the substrate and comprising a periphery-stepped upper surface facing away from the substrate, the periphery-stepped upper surface comprising a central upper surface and a peripheral lower surface surrounding and being lower than the central upper surface, the control chip comprising a plurality of second connecting electrodes formed on the central upper surface, and a plurality of third connecting electrodes formed on the peripheral lower surface connected to the second connecting electrodes; bonding wires configured to bond the first connecting electrodes to the third connecting electrodes; an ultrasonic transducer arranged on the control chip; and packing material configured to package the substrate, the bonding wires and the ultrasonic transducer as one module.