Fingerprint Sensor Package with Integrated Force Sensing

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Solution Overview

Problem

Integrating force sensing capabilities with fingerprint sensors in electronic devices, such as mobile phones, is challenging due to limited space and the need for additional components, which complicates the integration of separate force sensors with fingerprint sensors, resulting in a large component stack.

Innovation Solution

A fingerprint sensor package is developed with integrated force sensing capability using bond wire loops that connect a force sensing member to electrical connection pads, allowing for versatile electrical connections and minimal changes to the fingerprint sensor's appearance or integration, enabling the measurement of electrical properties altered by deformation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a separate force sensor is combined with a separate fingerprint sensor, then force sensing capability is added, but the component stack becomes relatively large

Engineering Contradiction:

Improveforce sensing capabilityVSAvoidcomponent stack height

Core Design Contradiction:

Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

The patent merges the force sensing function with the fingerprint sensor package by integrating a force sensing member into the same package structure. The bond wire loop serves dual purposes: electrical connection for the fingerprint sensor and mechanical support for the force sensing member, eliminating the need for separate force sensor components and reducing overall stack height.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The bond wire loop is designed to perform multiple functions simultaneously: it provides electrical connection for the fingerprint sensor, serves as a mechanical support structure, and enables force sensing capability. This multi-functionality reduces the number of separate components needed and compact the overall device structure.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Length of moving object

If space within electronic devices is limited, then device thickness is reduced, but integration of force sensor becomes problematic

Engineering Contradiction:

Improvedevice thicknessVSAvoidintegration of force sensor

Core Design Contradiction:

Length of moving objectVSEase of manufacture

Solution Approach 1:

The force sensing member is nested within the existing fingerprint sensor package structure. The bond wire loop extends from the substrate and provides both electrical connection and mechanical support for the force sensing member, allowing it to be integrated into the same package without increasing overall device thickness.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The bond wire loop extends in a substantially orthogonal direction from the substrate surface, creating vertical space utilization. This allows the force sensing member to be positioned above the substrate plane without increasing the horizontal footprint, enabling force sensing integration in thin devices.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Device complexity

If bond wire loops are used for electrical connection, then integration complexity is reduced, but manufacturing precision requirements increase

Engineering Contradiction:

Improveintegration complexityVSAvoidbond wire loop formation

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The bond wire loop structure is designed to automatically provide both electrical connection and mechanical support for the force sensing member. The loop's geometry and attachment points are configured so that the wire bonding process itself creates the necessary structural support, eliminating the need for additional support structures or complex assembly steps.

Inventive Principle:

Principle #25Self-service

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 solution improves the integration of force sensing with fingerprint sensors, allowing for effective measurement of applied force and providing haptic feedback, while maintaining a compact design by utilizing bond wire loops for electrical connections, which are formed during the same wire bonding step as the fingerprint sensor.

Implementation Method 1

an electrical property of the force sensing member is alterable in response to a deformation of the force sensing member

Methodology Applied

Scientific EffectDeformation: Deformation

Implementation Method 2

an electrical property of the force sensing member is alterable in response to a deformation of the force sensing member

Methodology Applied

Scientific EffectPiezoresistive effect: Piezoresistive Effect

Data Source

PatentUS11288476B2Fingerprint sensor package

Publication Date: 2022.03.29 FINGERPRINT CARDS IP AB

AI summary

The present invention generally relates to a fingerprint sensor package comprising a substrate having thereon a plurality of electrical connection pads, a fingerprint sensor arranged on the substrate and electrically connected to at least one of the electrical connection pads, a bond wire loop formed from a bond wire having two ends of which at least one end is mechanically and electrically attached to a first one of the electrical connection pads, and a force sensing member in electrical contact with the first electrical connection pad via an upper portion of the bond wire loop, and in electrical contact with a second one of the electrical connection pads different from the first electrical connection pad, wherein an electrical property of the force sensing member is alterable in response to a deformation of the force sensing member.