JP2005011212A - IC card and manufacturing method thereof - Google Patents

Abstract

To provide a highly reliable IC card that can be thinned and protects an IC chip from external stress.
A circuit board made of a flexible sheet material and having a circuit pattern formed thereon, a card board having an IC chip connected to the surface of the circuit board, a surface of the card board, Protective films 107 and 108 bonded to cover the back surface are provided, and this circuit board is formed in a two-layer structure.
[Selection] Figure 1

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an IC card and a method for manufacturing the same, and more particularly to improving the strength of a thin IC card.
[0002]
[Prior art]
The technological innovation surrounding IC cards with various functions mounted on a card with a semiconductor integrated circuit chip (IC chip) is steadily advancing, and attention has been paid to new functions of CPU, memory, card materials, etc. The trend is increasing.
[0003]
IC cards are classified into contact type and non-contact type. Recently, various types of IC cards (hybrid card, combination card) that integrate contact type and non-contact type by taking advantage of each feature. Etc.) has also appeared.
[0004]
For example, a non-contact type IC card has a mechanism in which an IC chip such as a coil and a CPU is mounted on the card, and the IC chip is driven by an electromotive force induced in the coil. As shown in FIG. 14, an example of this IC card is a coil pattern 102 made of an aluminum pattern formed on the surface of a circuit board 101 made of a polyethylene terephthalate (PET) film, and a face-down anisotropy to the coil pattern. The surface of a card substrate composed of a semiconductor integrated circuit chip (hereinafter referred to as an IC chip) 103 connected through a conductive film 104 and a reinforcing plate 105 attached to the back surface of the IC chip through a resin layer 106; The back surface is formed by covering with protective films 107 and 108 made of PET.
[0005]
Various devices have been devised for connecting the IC chip 103 and the circuit board 101, and a circuit pattern on the circuit board 101 is proposed in which the IC chip 103 is mounted via an anisotropic conductive film (for example, Patent Document 1).
[0006]
Since such an IC card is extremely thin, about 0.86 mm, when it is stored in a card case or the like and carried in a pocket or bag, it is easily damaged by stress applied to the card substrate. There's a problem.
[0007]
In particular, cracking and chipping of the IC chip is a problem, and reinforcement of the IC chip is an important issue. As described above, the reinforcing plate 105 having a size almost equal to that of an IC chip and a SUS Vickers hardness of 370 or more is used.
[0008]
[Patent Document 1]
JP 09-148378 A [Problems to be Solved by the Invention]
[0009]
However, such a conventional IC card has a problem that the IC chip is easily damaged by an external stress.
[0010]
In recent years, the demand for thinning has been increasing, and the demand for thinner ones is high. However, when trying to make a conventional IC card thinner, the reinforcing plate can be made thinner or the resin can be made thinner. It was necessary to do this, and it was easily damaged by external stress, and there was a limit to thinning.
The present invention has been made in view of the above circumstances, and an object thereof is to provide an IC card that protects an IC chip from external stress, can be thinned, and has high reliability.
[0011]
[Means for Solving the Problems]
Therefore, the IC card of the present invention is made of a flexible sheet material, and has a circuit board on which a circuit pattern is formed, and an IC chip connected to the surface of the circuit board so as to be connected to the circuit pattern. Comprising a substrate and a protective film bonded so as to cover a front surface and a back surface of the card substrate, wherein the circuit substrate is formed in a region surrounding the IC chip so as to form a two-layer structure. To do.
[0012]
With this configuration, since the circuit board has a two-layer structure in the area surrounding the IC chip, the entire thickness is increased because the two-layer structure is configured to avoid the area where the thickness is increased. And high strength can be achieved.
Further, since the two-layer structure is formed, the stress is relaxed between the respective layers, and the strength as an IC card is increased as compared with the case of the single-layer structure with the same thickness.
[0013]
According to the present invention, in the IC card, the circuit board has a first sheet substrate on which a circuit pattern is formed and an opening in the IC chip mounting region, and is superimposed on the first sheet substrate. And a second sheet substrate.
With this configuration, an IC card that is easy to assemble and highly reliable can be obtained.
In the IC card of the present invention, the second sheet substrate has a thickness of 12.5 to 25 μm.
By selecting in this range, there is an effect that the strength is increased and the thickness can be reduced.
[0014]
In the IC card of the present invention, the first sheet substrate has a thickness of 12.5 to 25 μm.
By selecting in this range, there is an effect that the strength can be similarly increased and the thickness can be reduced.
[0015]
Furthermore, in the IC card of the present invention, the second sheet substrate is formed of a material having lower rigidity than the first sheet substrate.
As a result, even when the circuit pattern is carried on the second sheet substrate, there is no positional deviation and high-reliability mounting is possible.
[0016]
In the IC card of the present invention, the second sheet substrate is made of a material having the same composition as the first sheet substrate.
By using materials having the same composition, the coefficients of thermal expansion are approximately the same, the occurrence of distortion during thermocompression bonding can be suppressed, and deviation and deflection can be reduced. It is also possible to use materials having the same composition and different thicknesses.
[0017]
In the IC card of the present invention, the second sheet substrate is made of the same material as the first sheet substrate.
Thereby, since it is not necessary to prepare many kinds of sheets, it is possible to obtain an IC card that is easy to manufacture and more reliable.
[0018]
In the IC card of the present invention, the second sheet substrate is thinner than the height of the bump formed on the IC chip.
With this configuration, the contact between the circuit pattern and the bump can be improved during mounting, and the reliability can be improved.
[0019]
Furthermore, in the IC card of the present invention, the first and second sheet substrates are fixed by vacuum bonding.
Thereby, no adhesive is required, and a clean and highly reliable circuit board can be obtained.
In the IC card of the present invention, the first and second sheet substrates are fixed via an adhesive resin layer.
With this configuration, a buffering effect by the adhesive resin layer can be obtained, and the strength can be further increased.
[0020]
In the IC card of the present invention, the IC chip is fixed to the circuit board via an insulating film sheet.
With this configuration, an insulating film sheet is interposed between the IC chip and the circuit board, so that the expansion of the circuit board due to external stress can be suppressed by this film sheet, and the stress applied to the IC chip is relieved. can do. Since the strength can be improved in this way, the thickness of the IC chip can be reduced, the thickness of the protective film and the thickness of the circuit board can be reduced, and the thickness can be reduced. It is desirable to use a film sheet having a higher rigidity than the flexible substrate constituting the circuit board.
[0021]
In the IC card of the present invention, a slit is formed around the IC chip.
With this configuration, cracking of the IC chip can be suppressed by releasing the elongation of the circuit board due to external stress through the slit. That is, due to the presence of the slit, the IC chip is fixed to the circuit board with a degree of freedom, and even if stress is applied to the circuit board, transmission to the IC chip is reduced. In this manner, stress can be relieved, and therefore the strength can be improved, so that the thickness of the IC chip can also be reduced. Moreover, the thickness of a protective film and the thickness of a circuit board can also be reduced, and thickness reduction can be achieved.
[0022]
In the IC card, the slit is provided in the vicinity of two corners on a diagonal line of the IC chip.
[0023]
With this configuration, since the slits are provided at two corners where the force is most likely to be applied, the stress can be released efficiently, and the presence of the slit does not cause a decrease in the strength of the circuit board itself.
[0024]
In the IC card, the slit is provided in the vicinity of the four corners of the IC chip.
[0025]
With this configuration, a suspended state in which the vicinity of the IC card is surrounded by a slit is taken, and stress can be released more efficiently.
The IC chip is fixed on the circuit board via an insulating film.
Further, in the IC card, since an insulating film sheet is interposed between the IC chip and the circuit board, the stress around the IC chip is efficiently released by the slit, and the circuit board due to external stress is released. Elongation can be suppressed by this film sheet, and the stress applied to the IC chip can be further relaxed.
[0027]
In the IC card, a reinforcing plate is disposed on the back surface of the IC chip.
With this configuration, since the IC chip is reinforced with an insulating film sheet on the front surface side and reinforced with a reinforcing plate on the back surface side, the stress resistance can be further improved.
[0028]
Furthermore, the film sheet is disposed on the entire surface of the IC chip except for portions corresponding to the connection terminals of the IC chip.
With this configuration, the connection with the circuit pattern on the circuit board is satisfactorily achieved by an anisotropic conductive film or the like, and the portions other than the connection terminals protruding on the surface of the IC chip are filled with the film sheet. In addition to the improvement, it is possible to increase the rigidity around the IC chip.
[0029]
The film sheet interposed between the circuit board and the IC chip is made of a polyimide film.
Usually, the circuit board is made of PET or the like, but with this structure, elongation due to stress can be suppressed by a polyimide film having rigidity higher than that of PET, so that stress applied to the IC chip can be relieved.
[0030]
In addition, if the film sheet is disposed in a region opposite to the reinforcing plate so as to be attached only to the region of the IC chip which is the weakest region, the cost can be reduced. Can be achieved. This is particularly effective in the case of a high-cost film such as polyimide.
[0031]
In the IC card of the present invention, the film sheet is composed of a polyimide film.
With this configuration, the elongation against stress is small, and the protection against the IC chip can be enhanced.
[0032]
In the IC card of the present invention, the circuit board is not more than a quarter of the thickness of the IC chip.
With this configuration, in addition to the above effects, the thickness can be further reduced.
If it is out of this range, there is a disadvantage that the thickness becomes too large. As a result of experiments, it was found that the strength of the circuit board can be maintained when the thickness of the circuit board is ¼ or less of the thickness of the IC chip.
[0033]
In the IC card of the present invention, the card substrate has a total thickness of 300 μm or less.
With this configuration, the thickness can be further reduced.
[0034]
The IC card of the present invention has a total thickness of 0.76 mm or less.
[0035]
The method of manufacturing an IC card of the present invention includes a step of attaching a second sheet substrate to the surface of a first sheet substrate made of a flexible sheet material, and preparing a circuit substrate on which a circuit pattern is formed, An IC chip is connected to the surface of the circuit board to form a card board, and a process of bonding a protective film by thermocompression bonding so as to cover the front and back surfaces of the card board.
By this method, the second sheet substrate is attached to the first sheet substrate in advance, so that the conventional manufacturing process can be used as it is, productivity can be improved, and easily A thin IC card with high strength can be formed.
[0036]
In the card manufacturing method of the present invention, the step of preparing the circuit board corresponds to a step of forming a circuit pattern on the surface of the first sheet substrate made of a flexible sheet material and an IC chip mounting region. And a step of attaching a second sheet substrate to the region and a region corresponding to the region where the circuit pattern is formed.
By this method, the circuit board can be continuously formed while being wound in a sheet state, and the productivity is improved.
[0037]
The IC card manufacturing method of the present invention includes a step of forming a slit in the vicinity of the IC chip mounting region of the circuit board.
[0038]
With this configuration, it is possible to easily form a highly reliable IC card only by adding a step of forming a slit. Further, by forming this slit in advance by punching or the like, it can be used for positioning in the IC chip mounting process.
[0039]
In the IC card manufacturing method of the present invention, the step of forming the card substrate includes a step of forming a desired element array on a semiconductor wafer, a step of dicing the semiconductor wafer to form an IC chip, Bonding the IC chip to the circuit board so as to sandwich the film sheet.
[0040]
Also by this method, an IC card with high strength can be easily formed. Further, in place of the insulating film sheet, workability can be further improved by using an insulating resin having a composition that increases rigidity after curing, such as a polyimide resin.
[0041]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an IC card according to an embodiment of the present invention and a manufacturing method thereof will be described in detail with reference to the drawings.
(First embodiment)
A sectional view of the IC card according to the first embodiment of the present invention is shown in FIG. 2A is a plan view showing a state where the protective films 107 and 108 of the IC card are removed, and FIG. 2B is an enlarged cross-sectional view of a main part. In the figure, the same parts as those described in the prior art are indicated by the same reference numerals.
This IC card is made of a flexible sheet material, and a card substrate having a circuit board 101 on which a circuit pattern is formed and an IC chip 103 mounted on the surface of the circuit board so as to be connected to the circuit pattern, Protective films 107 and 108 bonded so as to cover the front and back surfaces of the card substrate are provided, and the circuit board is constituted by a two-layer structure of a first sheet substrate 101a and a second sheet substrate 101b. It is characterized by that. The first sheet substrate 101a and the second sheet substrate 101b are joined by thermocompression bonding.
[0042]
That is, as shown in FIG. 3A, the circuit board is made of a PEN film having a thickness of 20 μm and includes a first sheet substrate 101a having a circuit pattern 102 formed of an aluminum foil having a thickness of 20 μm or less, As shown in FIG. 3B, the circuit board 101 (see FIG. 4) is joined by thermocompression bonding to a second sheet substrate 101b made of a PEN film having a thickness of 15 μm and having an opening W corresponding to the IC chip mounting region. ) Is formed.
[0043]
Then, a card substrate having an IC chip 103 connected to the surface of the circuit board 101 via a film sheet 100 made of a polyimide film having a thickness of 25 μm or less, and an adhesive resin 106 is fixed to the back side of the IC chip 103. And a protective film 107 and 108 made of polyethylene terephthalate (PET) bonded so as to cover the front and back surfaces of the card substrate.
[0044]
Here, bumps 109 are formed on the surface of the IC chip 103 so as to protrude as shown in the enlarged rear view and cross-sectional view of the main part of the IC chip in FIG. 5 and FIG. The circuit pattern 102 is connected via an anisotropic conductive film 110.
[0045]
This IC card is used as follows. For example, a circuit voltage of 3 V to 5 V is applied to Vcc of the bump (external contact terminal) of the IC card through the IC card reader / writer.
Further, a clock signal is supplied through the bump, and serial input / output of information is performed through the terminal (I / O terminal).
[0046]
Since the circuit board has a two-layer structure in the area surrounding the IC chip, it has a two-layer structure that avoids an area where the thickness is increased, so that high strength is achieved without increasing the overall thickness. Can be realized.
Further, since the two-layer structure is formed, the stress is relaxed between the respective layers, and the strength as an IC card is increased as compared with the case of the single-layer structure with the same thickness.
Since the stress can be relaxed in this way, the strength can be improved, and the thickness of the IC chip 103 can also be reduced. In addition, the thickness of the protective films 107 and 108 and the thickness of the circuit board 101 can be reduced, and the thickness can be reduced.
[0047]
Further, since the SUS reinforcing plate is provided on the back surface side of the IC chip, the IC chip is protected by the reinforcing plate 105 and the film sheet 100, and the connection portion between the bump and the circuit pattern is also the film sheet 100. The electrical connection is ensured because it is surrounded by. This reinforcing plate is made of SUS301 (stainless steel plate). Here, when the IC chip is 3 mm square, the reinforcing plate has a diameter of 6 to 8 mm. The shape of the reinforcing plate is preferably circular.
[0048]
In the same manner, only the reinforcing plate was made of different hardness and the strength was measured. This result also shows that it is desirable to use a material having a Vickers hardness of 530 or higher. That is, in the past, a material having a Vickers hardness of about 370 was used, but it was found that the strength was significantly improved.
[0049]
As the adhesive resin 106, it is desirable to use a resin that does not contain a release agent such as wax. As a result, the strength is improved by 30% or more compared to the conventional wax-containing resin. This improves the strength regardless of the presence or absence of the slit S.
[0050]
The total thickness of this IC card was 0.74 mm, and the thickness of the card substrate was 300 μm or less.
[0051]
This IC card could be maintained without any functional failure even after the test specified in JIS X 6303.
In addition, sufficient dynamic torsional strength could be maintained.
Furthermore, in the weight drop resistance test specified in JIS K 5600, the reliability could be maintained without causing peeling.
[0052]
Note that even if the thickness of the IC chip is reduced, the thickness of the protective film, and the thickness of the circuit board are reduced, a highly reliable IC card can be formed without causing a decrease in reliability.
Further, if the film sheet is attached only to the region where the stress is most likely to be applied to the IC chip, the cost can be reduced. This is particularly effective in the case of a high-cost film such as polyimide.
With this configuration, the elongation against stress can be reduced and the protection against the IC chip can be enhanced.
[0053]
In the IC card, the SUS plate is used as the reinforcing plate. However, the present invention is not limited to this, and may be made of other materials. In some cases, the reinforcing plate may be omitted.
[0054]
In addition to the PEN, other materials such as PET may be used for the circuit board.
[0055]
Next, an IC card manufacturing method according to an embodiment of the present invention will be described. 7 to 12 describe the manufacturing process of the IC card according to the embodiment of the present invention.
First, as shown in FIGS. 7 and 8, a circuit board 101 is formed. First, as shown in FIG. 7, a first sheet substrate 101a is formed. At this time, as shown in FIG. 7, a circuit pattern is printed using an aluminum paste in the printing unit 202 while running a belt-like film serving as the first sheet substrate 101a between the supply roll 200 and the take-up roll 201. Bake by heating. On the other hand, the opening W is punched by the punch portion 203 while the belt-like film serving as the second sheet substrate 101b is running. FIG. 3A shows a first sheet substrate on which a circuit pattern 102 made of an aluminum pattern is formed by printing. FIG. 3B shows the second sheet substrate 101b after the opening W is formed.
Thereafter, the second sheet substrate 101b is supplied while supplying the first sheet substrate 101a from the supply roller 200 as shown in FIG. This is taken up by the take-up roller 201.
[0056]
On the other hand, the IC chip is formed on the semiconductor wafer 1.
First, as shown in FIG. 9, a desired element array is formed on the semiconductor wafer 1, and as shown in FIG. 10, the bump 109, which is each connection terminal portion of each element constituting this element array, is raised. It forms so that it may become 25-40 micrometers. At this time, a film sheet 100 such as a polyimide film is attached to an area other than the bump forming area.
[0057]
Subsequently, as shown in FIG. 11, the IC chip 103 is divided along a dicing line DC.
[0058]
As shown in FIG. 12, the bump 109 of the IC chip 103 is connected to the circuit pattern 102 through the anisotropic conductive film 110.
Then, the reinforcing plate 105 having a thickness of 50 to 150 μm is fixed through an adhesive resin 106 which is a thermosetting epoxy compounded resin.
[0059]
Finally, pressure-bonding is performed with protective films 107 and 108 made of two polyimide sheets having a thickness of 12.5 to 25 μm to form an IC card as shown in FIG.
[0060]
According to this method, since the circuit board has a two-layer structure, stress can be relaxed even during assembly, and damage to the IC chip can be suppressed.
Therefore, the IC chip can be prevented from cracking during assembly, and the yield can be improved.
[0061]
In this way, it is possible to easily form a highly reliable IC card with good workability.
[0062]
The film sheet can be easily positioned because the film sheet is bonded at the wafer level and then divided into individual IC chips along the dicing line. Further, after the semiconductor wafer is diced to form an IC chip, the IC chip 103 may be bonded to the circuit board 101 so as to sandwich the film sheet 100.
[0063]
(Second Embodiment)
Further, the embodiment is characterized in that, in this example, the slit S is provided in the first sheet substrate constituting the circuit board 101 as shown in FIG.
Others are the same as those of the first embodiment shown in FIG.
[0064]
In addition, the slits are provided in the vicinity of the four corners of the IC chip, and the vicinity of the IC card is in a suspended state surrounded by the slits, so that stress can be released more efficiently. An interval L between the outermost edges of the slit S is 10 mm, a slit width is 1 mm, and four corners are formed in an L shape.
[0065]
With this configuration, since the slit S is formed around the IC chip 103 of the circuit board 101, the crack of the IC chip 103 can be suppressed by releasing the extension of the circuit board 101 due to external stress through the slit S. . In other words, the presence of the slit S causes the IC chip 103 to be fixed to the circuit board 101 with a degree of freedom, and transmission to the IC chip is reduced even if stress is applied to the circuit board. Since the stress can be relaxed in this way, the strength can be improved, and the thickness of the IC chip 103 can also be reduced. In addition, the thickness of the protective films 107 and 108 and the thickness of the circuit board 101 can be reduced, and the thickness can be reduced.
In addition, since the circuit board has a two-layer structure and the second sheet substrate is formed so as to cover the slit formed in the first sheet substrate, the stress can be efficiently released and the strength can be increased. The decrease is suppressed, and the presence of the slit does not cause a decrease in the strength of the circuit board itself.
[0066]
Also by this method, an IC card with high strength can be easily formed. Further, this insulating film sheet can be improved in workability even if it is formed by coating instead of an insulating resin having high rigidity at the time of curing, such as a polyimide resin.
In addition, although the reinforcing plate is formed in the embodiment, the reinforcing plate can be omitted if it is firmly fixed.
[0067]
【The invention's effect】
As described above, in the IC card of the present invention, since the circuit board is formed in a two-layer structure, the stress applied to the IC chip can be relieved and the strength can be improved.
In addition, the thickness of the IC chip can be reduced.
Furthermore, according to the method of the present invention, the IC chip is not damaged by the stress at the time of mounting, and it is possible to easily form a highly reliable IC card with no displacement.
[Brief description of the drawings]
FIG. 1 is a sectional view of an IC card according to a first embodiment of the present invention. FIG. 2A is a plan view of the IC card before forming a protective film, and FIG. 3A is a plan view showing a first sheet substrate, FIG. 3B is a plan view showing a second sheet substrate, and FIG. 4 is a plan view showing a circuit board according to the present invention. The figure which shows the surface side of the IC chip in 1st Embodiment of this invention [FIG. 6] Sectional drawing of the IC chip in 1st Embodiment of this invention [FIG. 7] IC in 1st Embodiment of this invention The figure which shows the manufacturing process of a card | curd. [FIG. 8] The figure which shows the manufacturing process of the IC card in the 1st Embodiment of this invention. [FIG. 9] The manufacturing process of the IC card in the 1st Embodiment of this invention. FIG. 10 is a diagram showing a manufacturing process of the IC card in the first embodiment of the present invention. FIG. 12 is a diagram showing an IC card manufacturing process in the first embodiment of the invention. FIG. 12 is a diagram showing an IC card manufacturing process in the first embodiment of the invention. FIG. 13 is a second embodiment of the invention. FIG. 14 is a diagram showing an IC card according to a conventional example. FIG. 14 is a diagram showing a conventional IC card.
DESCRIPTION OF SYMBOLS 1 Semiconductor wafer 101a 1st sheet substrate 101b 2nd sheet substrate 101 Circuit board 102 Circuit pattern 103 IC chip 104 Anisotropic conductive film 105 Reinforcement board 106 Resin layers 107 and 108 Protective film S Slit

Claims (14)

A circuit board made of a flexible sheet material and having a circuit pattern formed thereon;
A card substrate having an IC chip connected to the surface of the circuit board to be connected to the circuit pattern;
A protective film bonded to cover the front and back surfaces of the card substrate;
An IC card, wherein the circuit board is formed to have a two-layer structure in a region surrounding the IC chip. 2. The IC card according to claim 1, wherein the circuit board has a first sheet substrate on which a circuit pattern is formed, an opening in the IC chip mounting region, and is superimposed on the first sheet substrate. An IC card comprising a second sheet substrate that has been fastened. 3. The IC card according to claim 1, wherein the second sheet substrate is formed of a material having rigidity lower than that of the first sheet substrate. 3. The IC card according to claim 1, wherein the second sheet substrate is made of a material having the same composition as that of the first sheet substrate. 5. The IC card according to claim 1, wherein the first and second sheet substrates are fixed by vacuum bonding. 5. The IC card according to claim 1, wherein the first and second sheet substrates are fixed via an adhesive resin layer. 6. 7. The IC card according to claim 1, wherein the IC chip is fixed to the circuit board through an insulating film sheet. 2. The IC card according to claim 1, wherein the first sheet substrate includes a slit in the vicinity of the IC chip mounting area. 9. The IC card according to claim 1, wherein a reinforcing plate is disposed on the back surface of the IC chip. The IC card according to any one of claims 1 to 9, wherein the circuit board is equal to or less than a quarter of a thickness of the IC chip. The IC card according to claim 1, wherein the card substrate has a total thickness of 300 μm or less. The IC card according to any one of claims 1 to 11, wherein the total thickness is 0.76 mm or less. A step of attaching a second sheet substrate to the surface of a first sheet substrate made of a flexible sheet material, and preparing a circuit board on which a circuit pattern is formed;
A step of connecting an IC chip to the surface of the circuit board to form a card board;
And a step of joining the protective film by thermocompression bonding so as to cover the front and back surfaces of the card substrate. The IC card manufacturing method according to claim 13, wherein the step of preparing the circuit board includes:
Forming a circuit pattern on the surface of the first sheet substrate made of a flexible sheet material;
A method of manufacturing an IC card including a step of attaching a second sheet substrate to the surface of the first sheet substrate while avoiding a region corresponding to an IC chip mounting region and a region corresponding to the region where the circuit pattern is formed .

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