Optical fingerprint FPC with high flatness requirement

Abstract

The utility model discloses an optical fingerprint FPC with high flatness requirement, which comprises a TOP cover film windowing layer, a TOP circuit layer, a via hole layer, a Bottom circuit layer, a Bottom cover film windowing layer and a steel plate reinforcing layer, the steel plate reinforcing layer reinforces and shields a component area, the steel plate reinforcing layer reinforces the component area to ensure the flatness of the component area, and the thickness of the component area is reduced. And the steel plate reinforcing layer shields the influence of external electromagnetic waves on an internal circuit and the outward radiation of electromagnetic waves generated inside. According to the optical fingerprint FPC with the high flatness requirement, the height difference of the edge of the optical identification end FPC is reduced, so that the high-precision flatness requirement of optical fingerprints is realized.

Description

Technical Field

[0001] The utility model relates to the technical field of optical fingerprint FPC, in particular to an optical fingerprint FPC with high flatness requirement. Background Art

[0002] The under-screen optical fingerprint integrates the fingerprint recognition module into the screen, thereby further increasing the screen-to-body ratio, with convenience, high success rate and strong security as its irreplaceable advantages. The principle of the optical fingerprint FPC is to use photoelectric reflection technology, which is specially adapted to the OLED screen to emit light, penetrate the half-millimeter thick glass cover to reach the finger, and these reflected lights then penetrate the screen and reach the fingerprint to realize fingerprint recognition.

[0003] The FPC produced by the traditional copper plating design has a collapsed edge of less than 40um and a warped edge of less than 25um, which causes a height difference at the edge of the FPC at the optical recognition end. To solve the above problems, we proposed an optical fingerprint FPC with high flatness requirements. Utility Model Content

[0004] The main purpose of the utility model is to provide an optical fingerprint FPC with high flatness requirements, which can effectively solve the problems in the background technology.

[0005] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0006] An optical fingerprint FPC with high flatness requirement comprises a TOP cover film window layer, a TOP circuit layer, a via layer, a Bottom circuit layer, a Bottom cover film window layer, and a steel plate reinforcement layer. The steel plate reinforcement layer reinforces and shields a component area, reinforces a device area, ensures the flatness of the device area, and shields the influence of external electromagnetic waves on an internal circuit and the outward radiation of electromagnetic waves generated inside.

[0007] Preferably, the TOP covering film window layer uses PI film to remove the windows in the component area, and then adheres to the circuit area and bakes and cures to protect the circuit. The surface of the covering film of the TOP covering film window layer is silk-screened with 15UM thick text, and the content of the text includes product model and version information.

[0008] Preferably, the window areas of the window layer of the TOP cover film are all printed with 20UM exposure type solder resist ink, and the solder resist ink plays a solder resist role in the component area.

[0009] Preferably, the TOP circuit layer includes a device welding area, a packaging area and a circuit area, and a via layer is provided between the TOP circuit layer and the Bottom circuit layer.

[0010] Preferably, the conductive hole layer is drilled to form a hole wall on the cross section of the fingerprint FPC body.

[0011] Preferably, the Bottom circuit layer transmits signals to the TOP circuit layer through the via layer.

[0012] Preferably, the Bottom covering film window layer uses a PI film to remove the window in the grounding area of ​​the steel sheet, and then adheres to the line area and bakes and solidifies to protect the line.

[0013] Compared with the prior art, the utility model has the following beneficial effects: the optical fingerprint FPC with high flatness requirements, the Bottom covering film window layer can not only protect the circuit from being exposed and pressed, but also provide a grounding area for the steel plate reinforcement layer and the steel sheet grounding, while making the circuit area flexible and suitable for bending, and the device area is reinforced by the steel plate reinforcement layer to ensure the flatness of the device area, and shield the influence of external electromagnetic waves on the internal circuit and the electromagnetic waves generated inside from radiating outward. The utility model changes the design of the traditional ground wire laying, and by increasing the edge copper laying, the original copper laying distance from the outer shape is changed from 0.2MM on one side to 0.075MM. Thereby reducing the height difference of the edge of the optical recognition end FPC, so as to achieve the control of the collapsed edge of the optical recognition end FPC around less than 15um, and the upward warping less than 10um (measured by the steel sheet shrinking 0.1 position), and achieve the high-precision flatness requirements of the optical fingerprint. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the structure of an optical fingerprint FPC with high flatness requirements of the utility model;

[0015] Figure 2 This is a schematic diagram of the structure of an optical fingerprint FPC with high flatness requirements of the utility model;

[0016] Figure 3 This is a schematic diagram of the structure of an optical fingerprint FPC with high flatness requirements of the utility model;

[0017] Figure 4 This is a schematic diagram of the structure of an optical fingerprint FPC with high flatness requirements of the utility model;

[0018] Figure 5 This is a schematic diagram of the structure of an optical fingerprint FPC with high flatness requirements of the utility model;

[0019] Figure 6 This is a schematic diagram of the structure of an optical fingerprint FPC with high flatness requirements of the utility model;

[0020] Figure 7 This is a schematic diagram of the structure of an optical fingerprint FPC with high flatness requirements of the utility model;

[0021] Figure 8 The utility model is a schematic diagram of the structure of an optical fingerprint FPC with high flatness requirements.

[0022] In the figure: 1. Text; 2. Solder resist ink; 3. TOP cover film window layer; 4. TOP circuit layer; 5. Via hole layer; 6. Bottom circuit layer; 7. Bottom cover film window layer; 8. Steel plate reinforcement layer. DETAILED DESCRIPTION

[0023] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below in conjunction with specific implementation methods.

[0024] like Figure 1-7 As shown, an optical fingerprint FPC with high flatness requirements includes a TOP covering film window layer 3, a TOP circuit layer 4, a via layer 5, a Bottom circuit layer 6, a Bottom covering film window layer 7, and a steel plate reinforcement layer 8. The steel plate reinforcement layer 8 reinforces and shields the component area, reinforces the device area, ensures the flatness of the device area, and shields the influence of external electromagnetic waves on the internal circuit and the outward radiation of electromagnetic waves generated inside.

[0025] In this embodiment, the TOP covering film window layer 3 uses a PI film to remove the windows in the component area, and then adheres to the circuit area and bakes and cures to protect the circuit. The surface of the covering film of the TOP covering film window layer 3 is silk-screened with 15UM thick text 1. The content of text 1 contains product model and version information, which plays a role in identifying the product model version.

[0026] Specifically, the TOP cover film window layer 3 can protect the circuit from being oxidized due to exposure and can also make the circuit flexible and suitable for bending.

[0027] In this embodiment, the window areas of the window layer 3 of the TOP cover film are all screen-printed with 20UM of exposure type solder resist ink 2, and the solder resist ink 2 plays a solder resist role in the component area.

[0028] Specifically, the device pads are exposed and developed by exposure and development, so that the pad area can be soldered and the non-pad area can be soldered.

[0029] In this embodiment, the TOP circuit layer 4 includes a device welding area, a packaging area and a circuit area, and a via layer 5 is provided between the TOP circuit layer 4 and the Bottom circuit layer 6 .

[0030] Specifically, the device welding, packaging area, and pad area play the role of component support, respectively supporting the chip and BTB device and the IC.

[0031] In this embodiment, the via hole layer 5 forms a hole wall on the cross section of the fingerprint FPC body by drilling, and the Bottom circuit layer 6 transmits signals to the TOP circuit layer 4 through the via hole layer 5 .

[0032] Specifically, metal copper is deposited on the hole wall by chemical deposition, and the metal copper on the hole wall is further reinforced by electroplating, so that the TOP circuit layer 4 and the Bottom circuit layer 6 are connected, completing the transmission of signals between the optical sensing end of the TOP circuit layer 4 and the BTB end.

[0033] In this embodiment, the Bottom covering film window layer 7 uses a PI film to remove the window in the grounding area of ​​the steel sheet, and then adheres to the line area and bakes and solidifies to protect the line.

[0034] Specifically, the Bottom covering film window layer 7 can protect the circuit from being exposed and pressed, and can also provide a grounding area for the steel plate reinforcement layer 8 to ground the steel sheet, while making the circuit area soft and suitable for bending.

[0035] It should be noted that the utility model is an optical fingerprint FPC with high flatness requirements. The product model + version is printed on the surface of the covering film of the TOP covering film window layer 3 by silk screen printing, and 20UM exposure type solder mask ink 2 is silk screen printed on the entire window area of ​​the TOP covering film window layer 3. The device pads are exposed and developed by exposure and development to achieve solderability in the pad area and solder mask in the non-pad area. Then, the chip and BTB devices are placed on the pads by a placement machine, and then the welding is completed through reflow soldering. The IC is packaged in the bonding pad area by bonding gold wire. After metal copper is chemically deposited on the hole wall, the metal copper on the hole wall is reinforced by electroplating, so that the TOP circuit layer 4 and the Bottom circuit layer 6 are connected, completing the transmission of signals between the optical sensing end and the BTB end of the TOP circuit layer 4.

[0036] The above shows and describes the basic principle and main features of the utility model and the advantages of the utility model. Those skilled in the art should understand that the utility model is not limited by the above embodiments. The above embodiments and descriptions are only for explaining the principle of the utility model. Without departing from the spirit and scope of the utility model, the utility model may have various changes and improvements, which fall within the scope of the utility model to be protected. The scope of protection claimed by the utility model is defined by the attached claims and their equivalents.

Claims

1. An optical fingerprint FPC with high flatness requirements, comprising a TOP cover film window layer (3), a TOP circuit layer (4), a via layer (5), a Bottom circuit layer (6), a Bottom cover film window layer (7), and a steel plate reinforcement layer (8), characterized in that: The steel plate reinforcement layer (8) reinforces and shields the component area, the steel plate reinforcement layer (8) reinforces the device area and ensures the flatness of the device area, and the steel plate reinforcement layer (8) shields the influence of external electromagnetic waves on the internal circuit and the electromagnetic waves generated inside from radiating outward.

2. According to claim 1, an optical fingerprint FPC with high flatness requirement is characterized in that: The TOP covering film window layer (3) uses a PI film to remove the window in the component area, and then adheres to the circuit area and bakes and solidifies to protect the circuit. The surface of the covering film of the TOP covering film window layer (3) is silk-screened with text (1) with a thickness of 15UM, and the content of the text (1) includes product model and version information.

3. The optical fingerprint FPC with high flatness requirement according to claim 1, characterized in that: The window opening areas of the window opening layer (3) of the TOP cover film are all printed with 20 UM exposure type solder resist ink (2), and the solder resist ink (2) plays a solder resist role in the component area.

4. The optical fingerprint FPC with high flatness requirement according to claim 1, characterized in that: The TOP circuit layer (4) comprises a device welding area, a packaging area and a circuit area, and a via layer (5) is provided between the TOP circuit layer (4) and the Bottom circuit layer (6).

5. The optical fingerprint FPC with high flatness requirement according to claim 4, characterized in that: The conductive hole layer (5) is drilled to form a hole wall on the cross section of the fingerprint FPC body.

6. The optical fingerprint FPC with high flatness requirement according to claim 5, characterized in that: The Bottom circuit layer (6) transmits signals to the TOP circuit layer (4) through the via layer (5).

7. The optical fingerprint FPC with high flatness requirement according to claim 1, characterized in that: The bottom covering film window layer (7) uses a PI film to remove the window in the steel sheet grounding area, and then adheres to the line area and bakes and solidifies to protect the line.

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