Fingerprint Sensor Adhesive Bonding for Display Panel Attachment
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Solution Overview
Problem
Existing electronic devices with fingerprint sensing units face challenges in securely attaching fingerprint sensors to display panels, leading to potential detachment and errors in fingerprint sensing due to inadequate adhesive properties.
Innovation Solution
The use of a dual adhesive system, comprising a first adhesive portion surrounding the sensing area and a second adhesive portion surrounding the lateral portions of the fingerprint sensor, with specific width and thickness ratios relative to the sensor's thickness, to securely bond the sensor to the display panel, enhancing the joining force and preventing detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single adhesive portion is used to bond the fingerprint sensor to the display panel, then the device complexity is reduced, but the reliability of attachment is insufficient leading to potential detachment
Solution Approach 1:
The adhesive portion is divided into two distinct segments: a first adhesive portion positioned between the rear surface of the display panel and the upper portion of the fingerprint sensor, and a second adhesive portion positioned around the lateral portion of the fingerprint sensor. This segmentation allows each adhesive portion to perform its specific function optimally, with the first providing primary bonding and the second providing lateral support and preventing detachment, thereby resolving the contradiction between attachment reliability and device complexity.
Solution Approach 2:
The adhesive structure transitions from a single-plane adhesive application to a multi-dimensional configuration. The first adhesive portion operates in the vertical dimension (between panel and sensor), while the second adhesive portion operates in the lateral dimension (around the sensor sides). This dimensional expansion ensures comprehensive attachment reliability without excessive complexity.
2Strength
If the adhesive portion is made thinner to reduce overall device thickness, then the device becomes more compact, but the joining force between the fingerprint sensor and display panel is reduced
Solution Approach 1:
The adhesive system is segmented into two functional portions with different thickness requirements. The first adhesive portion can be thinner as it provides the primary bonding interface, while the second adhesive portion is configured with sufficient thickness (minimum width and thickness each at least 1/2 of fingerprint sensor thickness) to provide the necessary joining force and structural support, thereby resolving the contradiction between compactness and attachment strength.
Solution Approach 2:
Different regions of the adhesive structure are given different local qualities. The first adhesive portion has properties optimized for bonding to the display panel rear surface, while the second adhesive portion has properties (width, thickness, and positioning) optimized for providing lateral support and joining force. This local differentiation allows the overall device to be compact while maintaining sufficient attachment strength.
3Productivity
If the fingerprint sensor is positioned close to the side wall of the opening portion to maximize space utilization, then the device efficiency is improved, but the sensor becomes vulnerable to detachment
Solution Approach 1:
The second adhesive portion acts as an intermediary element between the lateral portion of the fingerprint sensor and the surrounding structure. It is positioned around the lateral portion with sufficient dimensions (minimum width and thickness each at least 1/2 of sensor thickness) to provide mechanical support and prevent detachment, even when the sensor is positioned close to the side wall for maximum space utilization. This intermediary adhesive structure resolves the contradiction between space efficiency and attachment stability.
Data Source
AI summary
An electronic apparatus includes a display panel including a front surface and a rear surface opposite to the front surface, a lower panel having an opening portion defined therein, a fingerprint sensor including an upper portion, a lower portion, and a lateral portion, the sensor being in the opening portion with a space from a side wall of the opening portion, and an adhesive portion to bond the fingerprint sensor to the display panel. The adhesive portion includes a first adhesive portion between the rear surface of the display panel and the upper portion of the fingerprint sensor and a second adhesive portion around at least a portion of the lateral portion of the fingerprint sensor, and a minimum width and a minimum thickness of the second adhesive portion are each at least ½ of a thickness of the fingerprint sensor.