Detailed Explanation of Fingerprint Module Glue Dispensing Process

### Detailed Explanation of the Fingerprint Module Glue Dispensing Process

The fingerprint module, as an important component in modern electronic devices, is widely used in smartphones, tablets, and various security devices. Its stability and reliability are crucial for user experience and device security. The glue dispensing process, as a key link in the manufacturing of fingerprint modules, not only concerns the structural strength of the module but also directly affects its lifespan and performance. This article will detail the various steps of the fingerprint module glue dispensing process and its importance.

The fingerprint module glue dispensing process is mainly applied to the fixation and protection of various components inside the module. A typical fingerprint recognition system includes a fingerprint recognition sensor, feature extraction/matching module, feature template library, and application software. At the hardware level, the fingerprint module consists of multiple precision components, such as sensor chips, flexible circuit boards (FPC), metal rings/frames, and driver chips. These components need to be fixed and connected through the glue dispensing process to ensure the stability and reliability of the module during operation.

The main steps of the fingerprint module glue dispensing process include:

**1. Fixing the Metal Ring/Frame to the FPC Substrate**

In this step, it is recommended to use low-temperature curing epoxy glue. Low-temperature curing epoxy glue has the characteristics of fast curing, long lifespan, and strong impact resistance, making it very suitable for fixing the metal ring/frame to the FPC substrate. The cured epoxy glue can provide a stable bonding effect, ensuring a firm and reliable connection between the metal ring/frame and the FPC substrate.

**2. Bonding the Sensor to the PCB Board**

The sensor is the core component of the fingerprint module, responsible for contacting and recognizing the user's fingerprint. In the bonding process between the sensor and the PCB board, low-temperature curing epoxy glue is also recommended. This glue not only provides high bonding strength but also adapts to various types of substrates, ensuring a stable and reliable connection between the sensor and the PCB board.

**3. Encapsulation of FPC Components**

The components on the FPC need to be encapsulated to protect them from external environmental interference and damage. In this step, it is recommended to use underfill epoxy. Underfill epoxy has high fluidity and high purity, allowing it to quickly fill the gaps between the components and the FPC, forming a uniform and void-free underfill layer. This not only enhances the fixation effect of the components but also improves the overall reliability of the module.

**4. Bonding the Sensor/Wafer to the FPC**

The bonding between the sensor chip or wafer and the FPC is another critical step. To ensure the stability and reliability of the connection, it is recommended to use underfill epoxy. This glue can provide excellent reinforcement protection and stress adjustment functions, ensuring that the connection between the sensor chip or wafer and the FPC maintains excellent performance over time.

**5. Glass Bonding**

In the fingerprint module, glass is usually used to protect the sensor from external scratches and impacts. During the bonding process of the glass, it is recommended to use UV curing glue. UV glue has excellent optical performance and weather resistance, cures quickly, and is non-polluting. It can ensure a tight connection between the glass and other components of the module while maintaining the module's aesthetics and transparency.

**6. Fixing the Sapphire Glass to the Sensor**

Some high-end fingerprint modules use sapphire glass as a protective layer to enhance the module's wear resistance and scratch resistance. In the fixing process between the sapphire glass and the sensor, it is recommended to use low-temperature curing reworkable liquid optical glue. This glue not only provides a stable bonding effect but also has reworkable characteristics, making it convenient for debugging and repairing during the module manufacturing process.

In addition to the main steps mentioned above, the fingerprint module glue dispensing process also includes some other key details. For example, during the glue dispensing process of the driver chip, underfill epoxy is also needed for underfilling; during the glue dispensing process of the fingerprint recognition main chip, it is necessary to ensure that the chip surface is free of scattered points and to strictly control the width of the overflow glue; during the dispensing of silver paste, it is necessary to ensure that the silver paste dots are on the copper sheet of the FPC and do not short-circuit after pressing; when fixing the metal ring with black glue, it is necessary to avoid silver paste and holes, ensuring that the amount of glue is sufficient and does not overflow to other positions.

In summary, the fingerprint module glue dispensing process is a complex and meticulous process involving multiple steps and the application of various glues. Each step requires strict control of process parameters and glue quality to ensure the stability and reliability of the module. With the continuous development of technology, the fingerprint module glue dispensing process is also constantly innovating and improving to meet higher performance and stricter quality requirements.