Fingerprint Module Heat-Pressed Adhesive Bonding
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Solution Overview
Problem
Fingerprint modules in mobile devices face issues with the lightweight fingerprint chip detaching from the cover plate due to inadequate adhesion, leading to defects and poor production quality.
Innovation Solution
A fingerprint module design where the fingerprint chip is heat-pressed onto the cover plate using a polyurethane adhesive, ensuring full contact and secure bonding, and a flexible circuit board is used to enhance stability and electrical connectivity, reducing the likelihood of detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a lightweight fingerprint chip is used, then the module weight is reduced and cost is lowered, but the chip becomes easily detached from the cover plate
Solution Approach 1:
The patent introduces an adhesive layer as an intermediary substance between the lightweight fingerprint chip and the cover plate. This adhesive mediator provides strong bonding force to compensate for the chip's light weight, preventing detachment while maintaining the weight reduction benefit. The adhesive acts as the intermediate medium that transfers and distributes mechanical stresses, securing the chip firmly to the cover plate.
Solution Approach 2:
The patent changes the physical and chemical parameters of the bonding interface by selecting adhesive materials with specific properties (viscosity, curing temperature, bond strength). By adjusting these parameters, the system achieves optimal attachment reliability for lightweight chips, transforming the bonding characteristics to match the reduced weight and surface area of modern fingerprint chips.
2Reliability
If the fingerprint chip is securely bonded to the cover plate, then detachment is prevented, but the bonding process becomes more complex
Solution Approach 1:
The patent replaces complex mechanical fastening systems (screws, clips, or rigid adhesives requiring precision alignment) with a simpler chemical bonding approach using adhesive layers. This substitution reduces the bonding process complexity while achieving reliable attachment, as adhesives can accommodate slight misalignments and do not require complex mechanical structures or assembly steps.
3Strength
If adhesive is used to bond the chip, then attachment strength is improved, but air gaps may form affecting signal reception
Solution Approach 1:
The patent applies local quality control by using adhesives with specific viscosity and spreading characteristics that ensure complete coverage of the chip's bonding surface. The adhesive is formulated to flow into and fill any surface irregularities or air gaps, creating a uniform bonding layer that maintains both strong attachment and optimal signal transmission by eliminating air pockets between the chip and cover plate.
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 solution provides a securely bonded fingerprint chip, improving the quality and waterproofing of the module, while also enhancing signal reception and reducing production costs by ensuring the chip remains firmly attached to the cover plate.
Implementation Method 1
the fingerprint chip is heat-pressed on the inner surface by adhesive, so that the adhesive fully contacts the cover plate and the fingerprint chip
Implementation Method 2
After heating the adhesive which is coated on the inner surface
Data Source
AI summary
A fingerprint module, a method for fabricating the same, and a mobile terminal having the same are provided. The fingerprint module has a cover plate and a fingerprint chip. The cover plate has an inner surface. The fingerprint chip is heat-pressed on the inner surface by adhesive, such that the adhesive fully contacts the cover plate and the fingerprint chip. The method includes after heating the adhesive which is coated on the inner surface of the cover plate, the fingerprint chip is laminated on the adhesive, such that the adhesive fully contacts the cover plate and the fingerprint chip.