JP2003065708A - Fingerprint detecting sensor and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fingerprint detecting sensor small in size. SOLUTION: A frame-like spacer 30 with the thickness of 50 μm and the width of 2 mm which is composed of adhesive materials, is formed along the periphery of a sensor substrate 20 a little larger than an area required for pressing a fingertip thereon, and the periphery of a form transferring film 10 is directly joined with the upper surface of the spacer 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fingerprint detecting sensor for detecting a fingerprint and a method for manufacturing the same, and more particularly to a technique for miniaturizing the fingerprint detecting sensor.

[0002]

2. Description of the Related Art In recent years, a fingerprint detection device has been attracting attention as a personal authentication device for a personal computer or the like. Since the same fingerprint does not exist in the world, the fingerprint detection device detects the user's fingerprint pattern and collates it with the fingerprint pattern registered in advance in the device, so that the user can be surely identified. It is possible to solve an inconvenient situation such as password misuse by another person, which has been a problem in the past.

FIG. 10 is a perspective view showing an example of a fingerprint detecting sensor 900 used in a conventional fingerprint detecting device, and a part of the upper surface is cut away for easy understanding of the internal structure. As shown in the figure, the conventional fingerprint detection sensor 9
In the case of 00, the sensor substrate 920 is fixed to the bottom portion 931 of the resin holder 930 with an adhesive or the like, and the step portion 932 above the sensor substrate 920 is fixed.
A stainless steel frame 91 with a thickness of about 0.2 mm
The flexible film 910 having the peripheral edge portion adhered thereto is placed on the substrate 1. The frame 911 is fixed to the holder 930 with an adhesive tape or the like.

The height of the stepped portion 932 is designed to be slightly higher than the surface of the sensor substrate 920 fixed to the bottom portion 931 so that the height between the surface of the flexible film and the surface of the sensor substrate is increased. It is configured to have a gap of about 100 μm. On the surface of the sensor substrate 920, T
Known sensor unit 9 made of FT (thin film transistor)
21 (for example, refer to Japanese Patent Laid-Open No. 8-68704), the surface pressure distribution due to the unevenness of the fingerprint is detected.

That is, the sensor section 921 is formed by forming innumerable TFTs in a matrix on a substrate and
A small conductive contact plate is connected to the source electrode of
The scanning electrode line connected to the gate electrode and drain electrode of the FT is the flexible wire 94 of the cable 940.
1, via a connector 942, is connected to a fingerprint detection apparatus main body (not shown).

On the other hand, the flexible film 910 disposed so as to face the sensor substrate 920 is made of one resin film having a thickness of about 10 μm, and the surface of the substrate side of the ITO (in
A conductive film such as a dium tin oxide (indium-tin oxide) film is formed. The conductive film is grounded via a resistor, and when the user presses the tip of a finger against the surface of the film, the mountain portion of the fingerprint (hereinafter referred to as “ridge”) pushes the film. , Along the ridge,
The conductive film on the back side is extruded and contacts the conductive contact plate,
As a result, a current flows between the drain electrode and the source electrode of the corresponding TFT. And each T
The ridge line of the fingerprint is detected by scanning the energized state of the FT.

A flexible film such as that used in the fingerprint detection sensor described above is a "shape transfer film" in the sense that the uneven shape of an object that is in contact with one surface is transferred to the back surface thereof almost faithfully. Can be called.

[0008]

Recently, mobile terminals, especially mobile phones, have been remarkably widespread, and the need for information security in these mobile phones is also increasing, and the demand for mounting a fingerprint sensor on the mobile terminals is increasing. I'm doing it. However, as described above, the conventional fingerprint detection sensor 900 has a configuration in which the sensor substrate 920, the frame 911 of the shape transfer film 910, and the like are incorporated in the holder 930, so that the size inevitably increases, and in particular, It was difficult to mount on a small mobile terminal.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a fingerprint detection sensor capable of detecting a fingerprint with a necessary minimum size and a manufacturing method thereof. .

[0010]

In order to solve the above problems, the present invention is a fingerprint detection sensor for detecting a fingerprint by transferring the uneven shape of the fingertip surface pressed on the surface of a flexible film to the back surface. A substrate for detecting a convex portion transferred to the back surface of the flexible film, and a spacer formed in a frame shape along the inner periphery of the substrate, the flexible film, A peripheral portion of the spacer is attached to the spacer, and the spacer is arranged to face the detection surface of the substrate at a predetermined interval.

Here, it is desirable that the spacer is made of an adhesive or an adhesive. In addition, the thickness of the spacer is preferably 5 to 500 μm. Further, the flexible film is held by the spacer while having a predetermined tension. In addition, the flexible film has a first thickness of 1 to 15 μm.
The second film and the second film may be bonded together via a buffer layer made of a material softer than the first and second films.

The buffer layer has a thickness of 1 to 50 μm.
It is desirable that it is m. Further, it is desirable that the buffer layer is made of an adhesive. Further, a plurality of switching elements are provided in a matrix on the main surface of the detection substrate opposite to the flexible film, and the surface of the flexible film opposite to the buffer layer is provided. The conductive film may be formed, and the fingerprint may be detected by bringing the conductive film of the convex portion pressed by the ridgeline of the fingerprint into contact with the switching element.

The present invention also provides a fingerprint detection sensor for transferring the uneven shape of the fingertip surface pressed against the surface of the flexible film to the back surface and detecting the fingerprint transferred to the back surface by the detection substrate. A manufacturing method, which comprises a first step of preparing a detection substrate, a second step of preparing a flexible film, and a third step of providing a spacer in a frame shape along the inner periphery of the detection substrate. And a fourth step of attaching a flexible film to the spacer, and a fifth step of heating the substrate to which the flexible film is attached at a predetermined temperature for a predetermined time. I am trying.

Here, it is preferable that the second step of preparing the flexible film includes a step of providing a ventilation hole at a position of the flexible film in the frame of the spacer. Further, the frame-shaped spacer provided in the third step may be configured such that a cutout portion or groove is formed in a part thereof and the cutout portion or groove serves as a ventilation hole.

Further, here, after the fifth step,
It is desirable to include a sixth step of sealing the vent holes. In addition, the present invention is a method for manufacturing a fingerprint detection sensor in which a concavo-convex shape of a fingertip surface pressed against the surface of a flexible film is transferred to the back surface thereof and is detected by a detection unit formed on a detection substrate. Then, the first step of preparing a large-sized substrate on which a plurality of detection parts are formed, and the second step of preparing a flexible film that is substantially the same as or larger than the large-sized substrate.
Step, a third step of forming a frame-shaped spacer around each detection portion on the large-sized substrate, and a fourth step of attaching the flexible film to the large-sized substrate via the spacer. The method includes a step, a fifth step of heating the large-sized substrate to which the flexible film is attached at a predetermined temperature for a predetermined time, and a sixth step of cutting the large-sized substrate into each detection substrate unit. It is characterized by that.

In the present specification, for example, "a ...
When the numerical range is represented as "b", the values of the lower limit a and the upper limit b are also included in the range.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a fingerprint detection sensor and a manufacturing method thereof according to the present invention will be described below. (Overall Configuration of Fingerprint Detection Sensor) FIG. 1 is an external perspective view of the fingerprint detection sensor 1 according to the present invention, in which a part of the shape transfer film 10 is cut away for easy understanding of the internal structure.

As shown in FIG. 1, the fingerprint detection sensor 1 is constructed by arranging the shape transfer film 10 on the sensor substrate 20 via a spacer 30 and connecting the cable 40 to the sensor substrate 20. The cable 40 is formed by sandwiching a flexible wire 41 made of copper as a material in a resin film.
Is a connector 42 attached to the end of the cable 40.
, And the connector 42 is connected to a fingerprint detecting apparatus main body (not shown).

FIG. 2 is an exploded view of the fingerprint detecting sensor 1. As shown in the figure, a frame-shaped spacer 30 is provided along the inside of the peripheral edge of the sensor substrate 20,
A sensor unit 60 is formed inside thereof. In this embodiment, the sensor substrate 20 is a glass substrate having a thickness of 31 mm × 20 mm and a thickness of 0.7 mm.
The size of the sensor unit 60 is 23 mm × 15 mm.

A wiring pattern (not shown for simplification) printed on the sensor substrate 20 is connected to each scanning electrode line of the sensor section 60, and the wiring pattern is connected to the cable 40. Will be extended to. On the other hand, in the cable 40, the flexible wire 41 is exposed at the connection portion with the wiring pattern, and the cable 40 is connected to the corresponding wiring pattern via an anisotropic conductive adhesive or the like. Note that this anisotropic conductive adhesive is a known adhesive that is configured so that metal powder is mixed into a resin material and that it has conductivity only in the pressure bonding direction.

A wiring pattern (not shown) for grounding is formed on the sensor substrate 20 side by side with a wiring pattern connected to the sensor section 60. The wiring pattern for grounding is silver paste (not shown). Is connected to the conductive film 14 (see FIG. 4) formed inside the shape transfer film 10. This wiring pattern is connected to one flexible wire 41 of the cable 40, and is grounded in the main body of the fingerprint detection device via the connector 42.

Further, along the inside of the peripheral portion of the sensor substrate 20, the outer shape is 28 mm × 20 mm, the thickness is 50 μm, and the width of the frame is 2.
A frame-shaped spacer 30 of mm is formed. An adhesive or an adhesive is used as a material for such a spacer, so that the shape transfer film 10 can be easily attached thereafter. In this embodiment, an acrylic pressure-sensitive adhesive having high heat resistance is used as the material of the spacer, but the material is not limited to this. However, in the case of a pressure-sensitive adhesive, it is necessary that the viscosity be high enough not to lose its shape, and in the case of an adhesive, it is desirable that the volume change is small when it is cured. Further, it is desirable that the adhesiveness does not deteriorate when the shape transfer film 10 is heated and thermally contracted as described later.

In addition to the above acrylic adhesives, silicone adhesives and the like are suitable as such adhesives, and epoxy resins are suitable as adhesives. As a method of forming the spacer, a known screen printing method is used to print an adhesive or an adhesive on the sensor substrate 20 in a frame shape having a thickness of 50 μm, or a release paper having a thickness of 50 μm.
After forming the pressure-sensitive adhesive or adhesive layer of m, another release paper is attached to the surface, and the other release paper is left by the die-cutting press, punched into a frame shape, and the punched one is released. A method in which the pattern paper is peeled off and a frame-shaped adhesive or adhesive is applied to the sensor substrate 20 and then the release paper on the opposite side is peeled off (hereinafter referred to as “release paper method”) can be used.

The peripheral portion of the shape transfer film 10 is adhered and fixed to the upper surface of the spacer 30 thus formed. A conductive film is formed on the back surface of the shape transfer film 10. When the fingertip is pressed against the surface of the shape transfer film 10, the conductive film 14 in the ridge portion of the fingerprint comes into contact with the detection surface of the sensor unit 60. Then, the fingerprint is detected.

The shape transfer film 10 is held by the spacer 30 with a certain tension so that it can be easily restored to its original position after being pressed. Further, 101 is a ventilation hole provided in the shape transfer film 10 in the manufacturing process, and 50 is an adhesive for closing the ventilation hole. The meanings of these will be described later. FIG. 3 is a schematic diagram showing the configuration of the sensor unit 60 formed on the sensor substrate 20.
The structure of the sensor unit 60 is known and has been described in detail in the above-mentioned Japanese Patent Laid-Open No. 8-68704, so only the outline will be described here.

As shown in FIG. 3, a plurality of scanning electrode lines 610 and 620 are formed in a direction orthogonal to each other on a substrate, and a TFT (thin film transistor) 630 is formed at a position where these electrode lines intersect. An insulating layer is provided so that the scanning electrode line 610 and the scanning electrode line 620 do not conduct at the intersecting position, and the gate electrode of the TFT 630 is connected to the scanning electrode line 620 and the drain electrode is connected to the scanning electrode line 610. The source electrode of the TFT 630 is connected to the conductive contact plate 631.

The scanning electrode lines 610 and 620 are connected to the above-mentioned wiring pattern (not shown) at the lead-out portions 611 and 621, respectively, and led out to the outside via the cable 40. (Structure of Shape Transfer Film 10) FIG. 4 is an enlarged cross-sectional view showing the laminated structure of the shape transfer film 10.

As shown in the figure, the shape transfer film 10
Is the first film 11, the buffer layer 12, and the second film 13.
And a conductive film 14. As the first film 11 and the second film 13, thin films having flexibility and not easily broken are used. Materials that satisfy such conditions include polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyimide (PI),
Polyether sulfone (PES) or the like is used. The thickness of each film is set in the range of 1 μm to 15 μm, and more preferably 2 μm to 8 μm. If it is less than 1 μm, it is easy to tear.
This is because if it exceeds μm, it becomes impossible to detect the fine unevenness of the fingerprint.

If the thickness is within the above range, the first
And the second film may have different thicknesses, and the materials are not necessarily the same as long as they are the same as those described above. In the present embodiment, the buffer layer 12 uses a resin film adhesive. As this adhesive, it is necessary to use one that is softer than the first film 11 and the second film 13 even after it has dried. Specifically, an acrylic adhesive, a silicone adhesive, a urethane adhesive Is used.

The conductive film 14 formed on the back surface of the second film 13 (the surface on the sensor substrate 20 side) may have a surface resistance of 1 kΩ / □ or less, such as gold, palladium,
A metal such as platinum, copper, chromium, nickel, titanium, molybdenum, or a metal oxide such as indium tin oxide or tin oxide is used and is formed by a known method such as a vacuum evaporation method or a sputtering method.

FIG. 5 is a sectional view showing a state where the surface of the shape transfer film 10 of the fingerprint detection sensor 1 is pressed by the fingertip 80. The shape transfer film 10 is deformed according to the ridge 81 of the fingerprint, and the conductive film 14 contacts the conductive contact plate 631. As described above, the conductive contact plate 631 is connected to the source electrode of the corresponding TFT 630, and
A predetermined voltage is applied to the drain electrode and the gate electrode of the TFT 630 from the external device via the scanning electrode lines 610 and 620, respectively, while the conductive film 14 has a resistance R.
Since it is grounded via the contact point, the contact between the conductive film 14 and the conductive contact plate 631 causes a current to flow between the drain electrode and the source electrode, and the switch is turned on.

The fingerprint detecting device main body (not shown) scans the scanning electrode lines 610 and 620 in order to bring them into an energized state.
FT630 is detected and the fingerprint pattern is reproduced. In addition,
The content of such data processing is already known and is not the subject matter of the present invention, and thus the description thereof is omitted. (Examples of Shape Transfer Film 10) Specific examples of the shape transfer film 10 will be described below. (Example 1) Structure First film 11 PEN film buffer layer 12 having a thickness of 4.5 μm Acrylic adhesive second film 13 having a thickness of 5 μm PEN film conductive film 14 having a thickness of 4.5 μm 14 PEN film conductive film having a thickness of 0.2 μm Palladium layer manufacturing method A 25 μm-thick PET film having a slight adhesive on the surface as a reinforcing material is bonded to one surface of a 4.5 μm-PEN film, and then the entire surface of the PEN film is formed by a sputtering method. Palladium is deposited to a thickness of 0.2 μm to form a conductive film. This sputtering was performed under the conditions of an operating pressure of 0.25 Pa in an Ar atmosphere and an applied voltage of 3 W / cm 2. Next, in order to protect the conductive film of palladium, a polyethylene film having a self-adhesive layer was attached to the surface, and then the PET film attached to the opposite surface was peeled off.

On the other hand, a PET film having a thickness of 25 μm, which has a slight adhesive on the surface as a reinforcing material, is also adhered to one surface of the other 4.5 μm PEN film, and then PEN is formed by a known coating treatment. An acrylic pressure-sensitive adhesive having a thickness of 5 μm was applied to the surface of the film, and the film was attached to the surface of the PEN film on which the conductive film was formed, opposite to the conductive film.

After that, the polyethylene film which protected the conductive film 14 was peeled off, and after being attached to the spacer 30, the PET film as the reinforcing material on the surface was peeled off. In addition,
Since the manufacturing method described above is common to each example except for the film thickness and the like, only the configuration will be described in Examples 2 to 4 below. (Example 2) First film 11 PEN film buffer layer 12 having a thickness of 4.5 μm Acrylic adhesive second film 13 having a thickness of 10 μm PEN film conductive film 14 having a thickness of 4.5 μm Palladium having a thickness of 0.2 μm Layer (Example 3) First film 11 PEN film buffer layer having a thickness of 6.0 μm 12 Acrylic adhesive having a thickness of 15 μm Second film 13 PEN film conductive film having a thickness of 6.0 μm 14 having a thickness of 0.2 μm Palladium layer (Example 4) First film 11 PEN film buffer layer 12 having a thickness of 6.0 μm Acrylic adhesive second film 13 having a thickness of 25 μm PEN film conductive film 14 having a thickness of 6.0 μm 0.2 μm In addition, in order to show the effect of the embodiment of the present invention, the shape transfer films of Comparative Examples 1 to 4 shown below were prepared. In Comparative Examples 1 to 3, only one film was used as in the conventional case, and in Comparative Example 4, two films were simply stacked as they were without using an adhesive. (Comparative Example 1) Constituent film PEN film conductive film having a thickness of 4.5 μm Palladium layer manufacturing method having a thickness of 0.2 μm A PEN film having a thickness of 4.5 μm has a slight adhesive on the surface as a reinforcing material on one surface thereof. After bonding a PET film having a thickness of 25 μm, palladium is deposited to a thickness of 0.2 μm on the entire surface of the PEN film by a sputtering method to form a conductive film. This sputtering was performed under the conditions of an operating pressure of 0.25 Pa in an Ar atmosphere and an applied voltage of 3 W / cm 2.

Thereafter, the conductive film 14 side was attached to the spacer 30, and the PET film as the reinforcing material on the surface was peeled off.
This manufacturing method is the same in the following Comparative Examples 2 and 3. (Comparative Example 2) Film PEN film conductive film having a thickness of 6 µm Palladium layer having a thickness of 0.2 µm (Comparative Example 3) Film PEN film conductive film having a thickness of 12 µm Palladium layer having a thickness of 0.2 µm (Comparative Example 4) Film PEN film conductive film having a thickness of 4.5 μm Palladium layer film having a thickness of 0.2 μm PEN film having a thickness of 4.5 μm A conductive film was formed on the film in the same manner as in Comparative Example 1, and then the film was opposite to the conductive film. Layered on. When no adhesive was used and Examples 1 to 4 and Comparative Examples 1 to 4 were evaluated for waist strength and fingerprint detection accuracy, the results shown in Table 1 below were obtained.

[0036]

[Table 1]

Here, the evaluation of the waist strength is performed by Toyo Seiki Mfg. Co.
Registered trademark). The measuring principle of this measuring device is to form a loop of a certain length with a film of a certain width, push the rod in the diameter direction of the loop, and press the loop to push the loop a specified distance. Is to measure. Therefore, it can be said that the larger the force (mgf) applied to crush the loop, the stronger the stiffness. In this experiment, the measurement conditions were a loop length of 60 mm,
Pushing speed 3.5mm / sec, pushing distance 15m
m.

Further, the fingerprint detection accuracy is visually confirmed, and the detected fingerprint pattern is reproduced on the monitor. If the ridge of the fingerprint is clear, it is judged as good (○), and the ridge of the adjacent ridge is determined. Those whose boundaries are difficult to understand are evaluated as (x). As can be seen from Table 1, the fingerprint detection accuracy is good in all of Examples 1 to 4 and the good result that the waist strength is about 20 times or more as compared with Comparative Examples 1 and 2 in the conventional configuration. was gotten.

Further, the waist strength of Examples 1 to 4 is more than double that of Comparative Example 3 in which a film having a thickness of 12 μm, which is close to the limit of fingerprint detection, is used for one film. . In particular, 2 PEN films with a thickness of 6 μm
In the example of Example 4 in which a 5 μm adhesive was used, the combined thickness of the two PEN films was Comparative Example 3.
Although the thickness of one PEN film is the same as 12 μm, the waist strength is more than 10 times that of Comparative Example 3.

On the other hand, in Comparative Example 4 in which only two 4.5 μm PEN films were stacked, not only the fingerprint detection accuracy was poor, but also PEN films of the same thickness were attached via an adhesive. The waist strength is overwhelmingly lower than that of the attached Example 1. From the above experimental results, it can be seen that the adhesive layer interposed between the two films greatly contributes to waist strength and detection accuracy.

This is considered to be due to the following reason. Regarding the strength of the waist In the case of Examples 1 to 4, since the two films can reinforce each other with the adhesive, the waist becomes strong. If only two sheets are stacked, the reinforcing effect is weak because they slide on each other. In addition, the fact that two films bonded together via an adhesive is stiffer than one film having the same thickness as the sum of the thicknesses of the films It is due to the addition of strength,
Since the distance between the two films becomes larger than that,
It is considered that this is because the moment of the reaction force by the other film increases with respect to the bending moment applied to one film.

Regarding the fingerprint detection accuracy, although the overall thickness of the shape transfer film 10 in which two sheets are overlapped with each other via an adhesive as in this embodiment is considerably large,
Still, the reason why the buffer layer 12 can detect the fingerprint well is
Since it is softer than the first film 11 and fixed to the first and second films, it also deforms itself following the deformation of the first film 11, and the deformation is transferred to the second film 13 below. It is thought that this is for effective communication. In the case of a thick single film, deformation is unlikely to occur due to the pressing of fingerprint ridges, and in the case of simply stacking two films, the air layer interposed between the two films may serve as a buffer layer. However, since it does not have the adhesiveness for sticking both films and does not have sufficient elasticity, it is difficult to convey the deformation of the first film 11 to the second film 13. The same applies when a fluid such as a liquid is used as the buffer layer.

From this principle, according to the present invention, even if the thickness of a single film is the limit of fingerprint detection (15 μm), it is possible to detect fingerprints to some extent by stacking them with an adhesive. To do. Further, as long as the material is softer than the two films and has a function of adhering these films, the material is not limited to the above-mentioned acrylic adhesive and other adhesives, and for example, a thin film made of urethane rubber can be used. The same good result can be obtained even when sandwiched by a sheet of PEN film and pressed.

As described above, since the shape transfer film 10 according to the present embodiment is constituted by bonding the first and second flexible films with the buffer layer interposed therebetween, the first and second flexible films are bonded. The flexible films assist each other to strengthen the body and extend the durability and life, and the buffer layer easily deforms following the deformation of the first flexible film. Is further transmitted to and deformed by the second flexible film, it is possible to effectively transmit the deformation of the fine concavo-convex shape applied to the first flexible film to the second flexible film. It is possible to obtain good shape transferability.

As described above, the fingerprint detection sensor 1 according to this embodiment is constructed by directly attaching the shape transfer film 10 to the frame-shaped spacer formed inside the peripheral portion of the sensor substrate 20. Therefore, the large-sized holder 930 as in the conventional art is not required, and the spacer 30 can be almost removed from the detection surface.
Since it can be formed in a larger size by the width of, it can be made much smaller than the conventional one.

By forming the shape transfer film 10 by sandwiching the cushioning material between the two resin films as described above, it is possible to dramatically extend the durability and life of the shape transfer film. Even if the film 10 is directly attached to the sensor substrate 20 via the spacer 30, the inconvenience of the life of the fingerprint detection sensor 1 as a whole does not occur.

In addition to the manufacturing method described below, there is a great merit in manufacturing cost. (Method for Manufacturing Fingerprint Detection Sensor) FIGS. 6 and 7 are schematic views showing manufacturing steps of the fingerprint detection sensor 1. First, a plurality of sensor units 60 and wiring patterns (not shown) are formed at a predetermined pitch on the surface of a large-sized glass substrate (hereinafter referred to as “master glass”) 200 by a known TFT manufacturing method (FIG. 6 ( a): In this embodiment, as an example, 4
Individual sensor units 60 are formed. ).

Then, a spacer 300 having a thickness of 50 μm is formed by an adhesive so as to surround each sensor portion 60.
Are formed (FIG. 6B). As the forming method, the above-mentioned screen printing method or release paper method is used.
Separately, prepare a shape transfer film 100 of the same size as or larger than the large-sized master glass 200,
The ventilation holes 101 are provided outside the respective sensor portions 60 and at positions corresponding to the inside of the frame of the spacer 300.

Then, an appropriate amount of silver paste for grounding the conductive film 14 is placed on a grounding wiring pattern (not shown), and then the shape transfer film 100 is applied to the spacer 300 of the master glass 200 for positioning. Then, the shape transfer film 100 is firmly adhered to the surface of the spacer 300 while pressing the roller 700 on it. When the roller is pressed, the volume between the shape transfer film 10 and the sensor substrate 20 at that portion decreases, and the shape transfer film 10
Part of the shape is in contact with the sensor part 60, but since the outside air flows into the inside through the ventilation hole 101 after passing through the roller, the shape transfer film 10 returns to its original state and comes into contact with the sensor part 60. The condition is resolved immediately. If the vent hole 101 is not provided, the inside of the shape transfer film 10 is hermetically sealed with a negative pressure, and the conductive film 14 of the shape transfer film 10 is sealed.
Since the contact between the sensor surface of the sensor unit 60 and the sensor surface is not released and the product becomes defective, the vent hole is indispensable in the manufacturing process of the fingerprint detection sensor according to the present invention.

Considering the ease with which air escapes when pressed,
As shown in FIG. 6C, the vent hole 101 is formed by the spacer 30.
It would be preferable to provide it at the corners on the downstream side in the moving direction of the roller in each frame of 0. Note that FIG. 6 (c)
In the figure, the state of pressure contact by rollers is shown very schematically, but in practice, a dedicated device for attaching the film to the substrate is used. This device has a main body for sucking and holding a film from behind, and a lid member attached to the main body via a hinge so as to be openable and closable, and sucking and holding the master glass 200 inside the lid member. It is configured to be able to. Then, the shape transfer film 100 and the master glass 200 are opposed to each other by closing the lid, and the roller housed in the main body is moved along the guide so that the shape transfer film 100 is pressed against the master glass 200. It is composed.

After sticking the shape transfer film 100, the process moves to FIG. 7A, and the master glass 200 is heated by a heater 710.
Put in and heat. A temperature sensor 7 is provided inside the heater 710.
12 and the heater 713, the power supply device 711 monitors the detection result of the temperature sensor 712 and the heater 713.
By controlling the power supply to
It is configured to maintain front and back.

The master glass 200 is the heater 71.
0 is heated at the temperature of 120 ° C. for 90 minutes.
After about 15 minutes, heat shrinkage occurs in the shape transfer film 100, but since the peripheral portion of the shape transfer film 100 is adhered to the spacer 300, an appropriate tension is generated, which causes the shape transfer film 100 to be pressed with a finger. The restoring force is increased, and the operability can be improved.

By further heating for about 75 minutes, the silver paste for grounding is cured and each conductive film of the shape transfer film 100 and each sensor portion 60 formed on the master glass.
Ensure the connection with the ground wiring pattern in. The heating temperature is appropriately set to a temperature not lower than the temperature at which the material causes heat shrinkage, depending on the material of the shape transfer film 10 used, and is not limited to 120 ° C.

Further, at the time of heat shrinkage, the shape transfer film 10
If is peeled off from the spacer 300, it is meaningless to heat because it generates tension. Therefore, it has a force for adhering the shape transfer film 100 against the tension of the shape transfer film 100 generated at the time of thermal contraction. Is selected. After the above heating, the master glass 200 is heated by the heater 710.
Then, it is cooled with a fan or the like and returned to room temperature, and thereafter, the adhesive 50 is supplied from each nozzle 720 to each vent hole 101 to seal them. The adhesive 50 used at this time needs to have the following requirements.

The viscosity is required to such an extent that the capillary phenomenon occurs and the adhesive does not flow inside. This is because if the adhesive flows into the inside, an insulating film is formed on the surface of the sensor unit 60 and the fingerprint cannot be detected. Do not shrink much when cured. When contracted, wrinkles are generated on the surface of the shape transfer film 10, which not only looks bad, but also deteriorates the fingerprint detection accuracy.

In the present embodiment, a silicone adhesive having a viscosity of 100 PaS (Pascal second) or 60 PaS, more specifically, a liquid silicone rubber is used as an adhesive satisfying the above two requirements. Good results have been obtained. Since these silicone adhesives are cured at room temperature, they are easy to handle. As in the present embodiment, the shape transfer film 10 is formed on the frame-shaped spacer 30.
By closely adhering to each other and sealing the vent hole 101, the inside is completely sealed and the following excellent effects can be obtained.

(1) It is possible to prevent dust and the like in the air from entering the inside of the fingerprint detection sensor 1, and it is possible to prevent defective detection due to dust, which has been a problem in the past. (2) The restorability of the shape transfer film 10 is improved. That is, since the inside is sealed, the shape transfer film 1
When 0 is pressed with the fingertip, the internal pressure increases, and at the moment when the fingertip is released, the shape transfer film 10 returns to the original state before being pressed by the air pressure.

(3) Further, the shape transfer film 10 is pressed against the concave portion of the fingerprint due to the increase of the internal pressure at the time of pressing, so that the concavo-convex state of the fingerprint can be more clearly highlighted on the conductive film 14. This improves the fingerprint detection accuracy. In this sealing step, the shape transfer film 100 is placed on an XY table, and it is moved in the X and Y directions by a predetermined amount according to a predetermined program, and at the same time the nozzle 720 synchronizes with this moving operation. It is configured to be performed automatically by supplying a fixed amount of adhesive.

Thereafter, the large-sized master glass 200 is cut into four sensor substrates 20 by a known glass cutting device equipped with a diamond cutter or the like (see FIG. 7).
(C)) After that, the cable 40 is connected via silver paste or the like to obtain a finished product as shown in FIG. In the conventional configuration, the sensor substrate 920 is fixed to the holder 930, and then the flexible film 910 attached to the stainless frame 911 is placed. Therefore, the glass chips generated when the master glass is cut are cut. However, there is a risk that the product may be attached to the surface of the sensor portion 921 of the sensor substrate 920, resulting in a defective product.
Since the shape transfer film 100 is attached in advance so as to cover the surface of the master glass 200, and the cutting is performed after the ventilation hole 101 is sealed, the glass chips are mixed inside and adhere to the sensor unit 60. Such a problem does not occur.

Further, compared with the manufacture of the conventional fingerprint detection sensor 900 as shown in FIG. 10, it can be rationalized or omitted in various points, and the manufacturing cost can be reduced. That is, in the conventional fingerprint detection sensor 900, the holder 9
30, the flexible film 910 is attached to the frame 9
11, the sensor substrate 920 is attached to the holder 9
Step of attaching to frame 30, frame 911 to holder 93
Although a number of steps such as a step of attaching the shape transfer film 10 to the 0 are required, the fingerprint detection sensor 1 according to the present embodiment is provided with the adhesive spacer 30 on the peripheral portion of the sensor substrate 20 and directly attaches the shape transfer film 10 thereto. Since it is attached, most of the above-mentioned conventional steps are unnecessary. Further, since a plurality of sensor units 60 are formed on one substrate and the shape transfer film 100 is attached and then cut at the final stage, it contributes to mass production. As a result, not only can the size be reduced compared to conventional products, but also significant cost reductions can be achieved.

In the present embodiment, for convenience of explanation,
Although an example in which four sensor substrates 20 are formed on one master glass has been shown, actually, a larger master glass is used to form a large number of sensor substrates 20 at one time. On the contrary, the glass substrates may be manufactured one by one on a small glass substrate. In this case, the efficiency of the mochiro production is reduced, but there is no change in that a small size and high performance fingerprint detection sensor can be formed.

<Modification> Needless to say, the contents of the present invention are not limited to the above-described embodiment, and the following modifications can be considered. (1) In the above embodiment, the thickness of the spacer 30 is 50 μm, but the thickness is not limited to this value. However, 5μ
When it is less than m, the conductive film 1 of the shape transfer film 10 is pressed at the time of pressing.
When 4 is brought into contact with the sensor unit 60, there is almost no deformation amount (elongation amount) of the shape transfer film 10, so that the restoring force to the original is small, and there is a possibility that it will be in a state of being in close contact with the sensor unit 60 without change. On the other hand, if it exceeds 500 μm,
The amount of deformation of the shape transfer film 10 when the conductive film 14 is pressed and brought into contact with the sensor portion 60 becomes too large, and plastic deformation may occur and the original position may not be restored. Therefore, the thickness of the spacer 30 is preferably set within the range of 5 to 500 μm.

(2) In the above embodiment, the ventilation hole 101 is provided in the shape transfer film 10, but the ventilation hole 101 is not limited to this location. For example, as shown in FIG. Spacer 31 cut out by w (about 1 mm)
Is formed on the sensor substrate 20, and the shape transfer film 1 is formed on the sensor substrate 20.
After attaching 0, as shown in FIG. 9, the cutout portion 32 is filled with the adhesive 51 from the tip of the nozzle 730 and sealed. At this time, it is desirable to use an adhesive having a viscosity that prevents the adhesive from flowing toward the sensor portion 60 due to the capillary phenomenon.

When the spacer 30 is thicker,
Instead of completely removing a part of the spacer 30 like the cutout portion 32, a groove for ventilation may be formed in the spacer 30. (3) In the above embodiment, the adhesive is used to seal the ventilation hole, but it may be an adhesive.
Of course, even in this case, it is needless to say that an appropriate viscosity that does not penetrate into the inside due to the capillary phenomenon is required.

(4) When a finger is pressed against the shape transfer film 10 of the fingerprint detection sensor, the skin oil of the fingertip may cause the fingertip and the sheet to come into close contact with each other, resulting in a sticky feeling.
Very uncomfortable. Further, when the fingerprint of another person is seen to remain on the surface of the shape transfer film 10, a psychological resistance occurs. In order to avoid these, the shape transfer film 10
It is desirable to finish the surface of R to a certain degree of roughness.

Generally, a method such as embossing or blasting is known for forming a rough surface on the film surface, but a known mat coat treatment is applied to an extremely thin film like the present invention. It is valid. In this matte coating process, a granular material called a filler made of acrylic resin, polystyrene resin, silicone resin, silica, etc. is added to a coating material such as acrylic resin, and the mixture is stirred so that it is dispersed uniformly in the coating material. After that, it is evenly coated on the film surface using a roller or the like and dried. At this time, if the coating amount is adjusted so that the thickness of the resin layer is smaller than the diameter of the filler granular material, a part of the filler is a layer of the coating material (resin layer).
Will be more prominent than this, and a certain rough surface will be formed.

Therefore, desired surface roughness and gloss can be obtained by appropriately adjusting the diameter and amount of the filler to be added and the thickness of the resin layer. However, if the resin layer is made too thick, the transferability of fingerprints will be deteriorated. Therefore, the thickness is preferably about 2 to 8 μm, and correspondingly, the diameter of the filler is selected to be 3 to 10 μm. Of course, in order to maintain good transferability, it goes without saying that the total thickness of the resin layer 80 and the first film 11 must not exceed 15 μm.

In addition, as shown in FIG.
Are formed in a matrix at a constant pitch, and the filler 81 is provided in each detection block (scan electrode lines 610, 6).
It is necessary to dispose at least one in a rectangular area surrounded by 20 and provided with one TFT 630.
If no filler is arranged corresponding to one detection block, the surface of the fingertip will touch the filler around it even if the ridge of the fingerprint is located at that portion. This is because the shape transfer film 10 cannot be pushed down by the ridge portion, and the transfer of the fingerprint to the conductive film 14 becomes defective.

In order to minimize the feeling of roughness when the fingertip is slid on the surface of the shape transfer film 10 while satisfying the above-mentioned conditions, the filler is substantially spherical and the size of the particles is uniform. It is preferable to be Therefore, the particle size distribution of the filler size (dispersion of particle size)
However, it is preferable to use the one having a thickness of ± 2 μm or less. If the particle size distribution exceeds that range, the user feels a snag on the fingertip and is not good in touch.

(5) In the above-described embodiment, since the shape transfer film 10 is formed by sticking two films together through the buffer layer, the shape transfer accuracy of the fingerprint is maintained and the rigidity of the shape transfer film is sufficiently maintained. The shape transfer film 10 can be improved and the service life of the shape transfer film 10 can be extended. However, from the viewpoint of only reducing the size of the fingerprint detection sensor 1, the shape transfer film 10 can be improved.
Needless to say, one flexible film as in the past may be used.

(6) Although the so-called surface pressure distribution detection type fingerprint detection sensor has been described in the above embodiment, the shape transfer film according to the present invention is an optical fingerprint detection sensor or a capacitance type fingerprint detection. It can also be applied to a sensor.
The former configuration is disclosed in, for example, Japanese Patent Laid-Open No. 10-269342, and the latter configuration is disclosed in, for example, Japanese Patent Laid-Open No.
It is disclosed in Japanese Patent Publication No. 1-155837. In the case of the optical type, a normal transparent glass substrate is used instead of the sensor substrate 20, and an optical sensor is arranged behind it.

All of them detect a variation in the amount of light reflection or capacitance due to the unevenness of the fingerprint transferred on the film to obtain a fingerprint pattern, and the shape transfer film 10 of the present invention can be effectively used. . Conventionally, in these detection methods, there is a high possibility that erroneous detection may occur due to sweat on the fingertip surface, outdoor weather (particularly rain), but the shape transfer film 10 is interposed between the sensor surface and the fingertip. This makes it possible to detect fingerprints with good usability and high accuracy.

However, since a light source is required in the case of the optical type, the size of the depth of the detecting portion tends to be slightly larger than that of the surface pressure distribution detecting type using the above-mentioned TFT. By directly attaching the shape transfer film 10 to the substrate as described above, the area of the surface portion can be reduced, so that it can be more easily mounted on a small device such as a mobile terminal as compared with the related art.

When used for an optical fingerprint detection sensor, it is not necessary to have conductivity, so the conductive film 1
4 is unnecessary.

[0075]

As described above, according to the fingerprint detecting sensor of the present invention, the substrate for detecting the convex portion transferred to the back surface of the flexible film and the inside of the peripheral portion of the substrate are provided. And a spacer formed in a frame shape so that the flexible film is configured such that a peripheral portion of the flexible film is attached to the spacer, and the flexible film is arranged to face the detection surface of the substrate at a predetermined interval. Since there is no need for a holder member to hold the substrate and film as in the past, it is possible to obtain an extremely small fingerprint detection sensor in which the width of the frame-shaped spacer is larger than the size required for fingerprint detection. it can.

[Brief description of drawings]

FIG. 1 is a perspective view of a fingerprint detection sensor according to an embodiment of the present invention.

FIG. 2 is an exploded view of the fingerprint detection sensor.

FIG. 3 is a diagram showing an outline of a circuit configuration of a sensor unit in the fingerprint detection sensor.

FIG. 4 is a longitudinal sectional view showing a laminated structure of a shape transfer film used for a pressing portion of the fingerprint detection sensor.

FIG. 5 is a schematic cross-sectional view of the fingerprint detection sensor showing a state where the shape transfer film is pressed by the ridges of the fingerprint.

FIG. 6 is a diagram illustrating a manufacturing process of the fingerprint detection sensor according to the present invention.

FIG. 7 is a diagram for explaining the continuation of the manufacturing process in FIG.

FIG. 8 is an explanatory diagram of a case where a part of a frame-shaped spacer is cut off to form a ventilation hole.

FIG. 9 is a diagram showing a state in which a vent hole provided in the spacer is sealed with an adhesive.

FIG. 10 is a diagram showing a configuration of a conventional fingerprint detection sensor.

[Explanation of sign]

1 Fingerprint detection sensor 10 Shape transfer film 20 sensor board 30,31 spacer 32 excision 40 cable 41 flexible wire 50,51 adhesive 50 vents 60 sensor 100 shape transfer film 101 Vent 200 master glass 300 spacer Scan electrode lines 610 and 620 630 TFT 700 rollers 710 heating chamber 711 power supply 712 Temperature sensor 713 heater 720,730 nozzle

Claims (13)

[Claims] 1. A fingerprint detection sensor for detecting a fingerprint by transferring an uneven shape of a fingertip surface pressed on the surface of a flexible film to a back surface, wherein a convex portion transferred to the back surface of the flexible film. A substrate for detecting, and a spacer formed in a frame shape along the inside of the peripheral portion of the substrate, the flexible film, the peripheral portion of the flexible film is adhered to the spacer, A fingerprint detection sensor, which is arranged to face a detection surface at a predetermined interval. 2. The fingerprint detection sensor according to claim 1, wherein the spacer is made of an adhesive or an adhesive. 3. The spacer has a thickness of 5 to 500 μm.
The fingerprint detection sensor according to claim 1 or 2, wherein 4. The fingerprint detection sensor according to claim 1, wherein the flexible film is held by the spacer while having a predetermined tension. 5. The flexible film is 1 to 1, respectively.
The first and second films having a thickness of 5 μm are bonded together via a buffer layer made of a material softer than the first and second films. The fingerprint detection sensor according to any one of the above. 6. The fingerprint detection sensor according to claim 5, wherein the buffer layer has a thickness of 1 to 50 μm. 7. The fingerprint detection sensor according to claim 5, wherein the buffer layer is made of an adhesive. 8. A plurality of switching elements are provided in a matrix on a main surface of the detection substrate which faces the flexible film, and the switching element is provided on the opposite side of the flexible film from the buffer layer. A conductive film is formed on the surface, and the fingerprint is detected by contacting the conductive film of the convex portion pressed by the ridge of the fingerprint with the switching element. Item 8. The fingerprint detection sensor according to any one of items 1 to 7. 9. A method of manufacturing a fingerprint detection sensor, wherein the uneven shape of a fingertip surface pressed on the surface of a flexible film is transferred to a back surface and a fingerprint transferred to the back surface is detected by a detection substrate. A first step of preparing a detection substrate, a second step of preparing a flexible film, and a third step of providing a frame-like spacer along the inner periphery of the detection substrate, A fingerprint detection sensor, comprising: a fourth step of attaching a flexible film to the spacer; and a fifth step of heating the substrate to which the flexible film is attached at a predetermined temperature. Production method. 10. The second step of preparing the flexible film includes the step of providing a vent hole in a position of the flexible film within the frame of the spacer. A method for manufacturing the fingerprint detection sensor described above. 11. The frame-shaped spacer provided in the third step has a cutout portion or groove formed in a part thereof, and the cutout portion or groove is configured to be a ventilation hole. The method of manufacturing a fingerprint detection sensor according to claim 9, wherein the fingerprint detection sensor is manufactured. 12. The method according to claim 10, further comprising a sixth step of sealing the vent hole after the fifth step.
Alternatively, the method for manufacturing the fingerprint detection sensor according to Item 11. 13. A method for manufacturing a fingerprint detection sensor, wherein a concavo-convex shape on the surface of a fingertip pressed on the surface of a flexible film is transferred to the back surface of the fingertip and detected by a detection unit formed on a detection substrate. A first step of preparing a large-sized substrate on which a plurality of detection portions are formed, a second step of preparing a flexible film that is substantially the same as or larger than the large-sized substrate, A third step of forming a frame-shaped spacer around each detection unit on the substrate, a fourth step of attaching the flexible film to the spacer, and a large-sized format in which the flexible film is attached. 5. A method of manufacturing a fingerprint detection sensor, comprising: a fifth step of heating the substrate at a predetermined temperature; and a sixth step of cutting the large-sized substrate into each detection substrate unit.