IC sheet

Abstract

To provide an IC sheet in which an IC chip is suitably protected from point-like pressure and can be made thinner.SOLUTION: An IC sheet 1 is provided with an IC module 100 including a lead frame 101 and an IC chip 13 arranged on the lead frame and in which the IC chip is sealed with a resin mold 102, a coil antenna 12 connected to the IC chip, two core sheets 30 arranged to sandwich the coil antenna 12 and having one hole in one side in which the lead frame can be entered and another hole in the other side in which the resin mold can be entered, two over-sheets 20 arranged to sandwich the core sheets, and a shock-absorbing layer 14 formed using a polyurethane-based moisture-curable adhesive and arranged between the lead frame and the over-sheet facing the lead frame.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an IC sheet to be incorporated in a booklet such as a passport, and more particularly to an IC sheet that can improve resistance to point-like impacts on an IC chip. [Background technology]

[0002] Generally, in media equipped with IC chips, such as IC sheets and ID cards, one method for improving resistance to external impacts, particularly point-like impacts that can easily damage IC chips, is to provide a reinforcing material on the IC of a module equipped with the IC (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-54032 A Summary of the Invention [Problem to be solved by the invention]

[0004] One of the booklets to which IC sheets are applied is the passport. Conventional passports often have a structure in which the IC sheet is protected by being sandwiched between sheet-like materials, but in order to improve the ease of handling of passports, there is a growing trend around the world to make the IC sheet thinner and to integrate the page on which the IC sheet is placed with the page on which the photograph is placed. For this reason, there is a growing demand for IC sheets with a thickness of approximately 350 to 420 μm, which is about half the conventional thickness. However, with such a thickness, sufficient protection from the sheet-like member cannot be expected, and a new problem has arisen in that reinforcing materials such as those described in Patent Document 1 cannot be applied due to their thickness.

[0005] In view of the above circumstances, an object of the present invention is to provide an IC sheet that can adequately protect an IC chip from point-like pressure and can also be made thinner. [Means for solving the problem]

[0006] The present invention is an IC sheet comprising: an IC module including a lead frame and an IC chip arranged on the lead frame, the IC chip being sealed with a resin mold; an antenna connected to the IC chip; two core sheets arranged to sandwich the antenna, one having a hole through which the lead frame can enter and the other having a hole through which the resin mold can enter; two oversheets arranged to sandwich the core sheet; and an impact absorbing layer formed using a polyurethane-based moisture-curing adhesive and arranged between the lead frame and the oversheet facing the lead frame. The IC sheet of the present invention may further comprise a second impact absorbing layer disposed between a core sheet having a hole through which a resin mold can enter and an oversheet facing the core sheet, and formed using a polyurethane-based moisture-curing adhesive. Effect of the Invention

[0007] According to the present invention, it is possible to provide an IC sheet in which an IC chip is suitably protected from point-like pressure and which can also be made thinner. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram showing a booklet provided with an IC sheet according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic cross-sectional view of the IC sheet. [Diagram 3] FIG. 4 is a schematic cross-sectional view of an IC sheet according to a second embodiment of the present invention. [Figure 4] 5(a) to 5(c) are schematic diagrams showing examples of how the adhesive that becomes the second impact absorbing layer is dropped. [Diagram 5] FIG. 11 is a schematic diagram showing an arrangement of a second shock absorbing layer according to a modified example. [Figure 6] 13(a) to 13(c) are schematic partial enlarged views of an IC sheet according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 is a schematic diagram showing an example of a booklet 200 including an IC sheet 1 according to this embodiment. In this example, the IC sheet 1 is sandwiched and joined between two paper base materials, and is bound between the front and back covers 201. This allows the area where the IC sheet 1 is arranged to have an appearance that does not look out of place with other pages of the booklet made only of paper.

[0010] In the case of passports and the like, writing is not generally done directly on the area where the IC sheet 1 is placed, but writing or a seal may be done on the regular page 202 placed over the IC sheet 1, in which case pressure is applied in small spots to the IC sheet 1 through the regular page 202. Therefore, it is necessary to protect the IC chip built into the IC sheet from such pressure and maintain a communicable state for a long period of time.

[0011] 2 is a schematic cross-sectional view showing an exploded view of the IC sheet 1 according to this embodiment. The IC sheet 1 includes an IC module 100 including an IC chip, and two types of resin sheets, an over-sheet 20 and a core sheet 30.

[0012] The IC module 100 has a configuration in which an IC chip 13 arranged on a lead frame 101 is sealed with a resin mold 102 . There are two core sheets 30, one of which has a hole through which the lead frame 101 can enter, and the other has a hole through which the resin mold 102 can enter. An embedded type coil antenna 12 using metal wire is provided on one of the core sheets 30, and is connected to the IC chip 13 via the lead frame 101. In this way, the coil antenna 12 is sandwiched between the two core sheets 30. Examples of materials for the coil antenna 12 include copper, gold, silver, etc.

[0013] Examples of materials for the core sheet 30 include polyester resin, acrylonitrile butadiene styrene copolymer resin (ABS), vinyl chloride-vinyl acetate copolymer resin, PET-G, polypropylene, polycarbonate, triacetate, polyamide, etc., but are not limited to these, and other materials can be used as long as they meet the standards of ISO / IEC7810 ID·1 and ICAO ID·3. Furthermore, the core sheet 30 may have a structure in which a plurality of layers made of the above-mentioned materials are laminated, or one layer may be configured to include a plurality of types of materials.

[0014] The oversheets 20 are two sheet-like members without holes, and cover the holes formed in the core sheet 30 by sandwiching the IC module 100 and the core sheet 30 in the thickness direction. The material of the over-sheet 20 may be different from that of the core sheet 30. Alternatively, the over-sheet 20 may be made of the same material such as polycarbonate but with a different molecular weight. Alternatively, the over-sheet 20 and the core sheet 30 may be made of the same material. The over-sheet 20 and the core sheet 30 may be laminates made of multiple layers.

[0015] An impact absorbing layer 14 made of a polyurethane moisture-curing adhesive is disposed between the lead frame 101 and the oversheet 20. The impact absorbing layer 14 will be described in detail later.

[0016] With the above-described structure, the IC sheet 1 of this embodiment is configured as a sheet having flat surfaces on both sides. Conventionally, many passports and other documents equipped with an IC chip have a thickness of about 600 to 800 μm at the part where the IC chip is embedded. With such dimensions, the oversheet can be made thick enough to absorb impacts on the IC chip, and even when the reinforcing members described in Patent Document 1 and other documents are arranged, they can be arranged relatively easily within the thickness of the core sheet.

[0017] However, in order to further enhance security, there is a growing demand to add anti-counterfeiting technologies such as printing personal information or holograms in the area where the IC chip is embedded. However, if these features are added to the conventional thickness of the passport, the thickness of the area where the IC chip is embedded will become even thicker, making the passport less easy to handle. For this reason, as mentioned above, there is an increasing demand for IC sheets with a thickness of approximately 350 to 420 μm, which is about half the thickness of conventional sheets. However, with such a thickness, the protection provided by the core sheet cannot be expected to be sufficient, and a new problem has arisen in that reinforcing members such as stainless steel plates that have been used conventionally cannot be applied due to their thickness.

[0018] The inventors have conducted extensive research into a structure that can adequately protect IC chips from impact under such constraints. As a result, they have found that, among various materials, polyurethane-based moisture-curing adhesives have particularly excellent impact absorption properties under such conditions. This is believed to be because the rigidity of the impact absorbing layer prevents excessive deformation at the impact site of the oversheet or core sheet in contact with the impact absorbing layer, and the impact absorbing layer disperses the point-like impact applied to the IC chip.

[0019] The inventors' study revealed that when an impact absorbing layer is formed using a polyurethane moisture-curing adhesive, the thickness of the impact absorbing layer after processing into an IC sheet is about 5 μm to 80 μm, which is sufficient to protect the IC chip. Furthermore, when using a polyurethane moisture-curing adhesive, it is also found that it is preferable that the adhesive has a melt viscosity of 2000 to 40000 mPa·s (milli-Pascal seconds) at 100°C to 120°C before curing, a softening point of 40 to 80°C, and that the storage modulus of the impact absorbing layer after curing (at 25°C) is about 20 to 100 megapascals (MPa).

[0020] The impact absorbing layer 14 may be disposed on the resin mold 102, but is always provided at least on the lead frame 101 side. The impact absorbing layer 14 may be formed on either the lead frame 101 side or the over sheet 20 side, as long as it is between the lead frame 101 and the over sheet 20 facing the lead frame. The inventors' investigations have revealed that although resin mold 102 itself has a certain degree of shock absorbing ability, lead frame 101 does not have sufficient shock absorbing ability due to its material, and shock applied to lead frame 101 is transmitted to the IC chip with almost no attenuation. For this reason, the protection effect of the IC chip by providing a shock absorbing layer on the lead frame 101 side is significantly greater than that of providing it on the resin mold 102 side, and is essential in the present invention. If a shock absorbing layer is also provided on the resin mold 102 side, shock resistance will be further improved.

[0021] The impact absorbing layer 14 only needs to cover at least a part of the IC chip 13 in a plan view in which the planar IC sheet 1 is viewed in the normal direction, and does not necessarily need to cover the entire IC module 100. The impact absorbing layer 14 only needs to cover 10% of the resin mold 102 in a plan view in which the planar IC sheet 1 is viewed in the normal direction after generally covering the IC chip 13 in a plan view. When the IC chip 13 is partially covered, it is preferable that the impact absorbing layer 14 covers 5% or more of the resin mold 102. The impact absorbing layer 14 preferably completely covers the IC chip 13, but it is preferable that the impact absorbing layer 14 covers 50% or more of the area of ​​the IC chip 13 in a plan view in which the planar IC sheet 1 of the IC chip 13 is viewed in the normal direction, and a part of the peripheral portion, etc., may not be covered by the impact absorbing layer 14. That is, the impact absorbing layer only needs to cover the entire or a part of the IC chip 13 in a plan view of the IC sheet 1. Or, it only needs to cover the entire or a part of the resin mold 102 in a plan view of the IC sheet 1. When covering the entire IC chip 13, the area of ​​the shock absorbing layer 14 may be larger than that of the IC chip 13. In this case, it is easy to align the position of the shock absorbing layer 14 on the IC chip. The shock absorbing layer 14 may or may not cover the entire IC module 100. By forming the shock absorbing layer 14 in a shape that covers only a part of the IC chip or IC module, the amount of material used that constitutes the shock absorbing layer can be significantly reduced.

[0022] As described above, according to the IC sheet 1 of this embodiment, by forming the shock absorbing layer with a polyurethane moisture-curing adhesive, it is possible to sufficiently increase the point impact resistance of the IC chip with a significantly thinner structure than the conventional technology. As a result, it is possible to realize an IC sheet with sufficient point impact resistance even with a thickness of about half that of the conventional one. As a result, it is possible to contribute to the production of passports with higher security and excellent handling properties.

[0023] The shock absorbing layer according to this embodiment can be formed by dropping and curing an uncured polyurethane moisture-curing adhesive. In addition, the position, thickness, planar dimensions, etc. of the shock absorbing layer can be changed very easily by changing the drop position, drop amount, and drop shape. As a result, it can flexibly respond to various changes, and its versatility in mass production is extremely high. However, the shock absorbing layer according to the present embodiment is not limited to being formed by dropping an adhesive. For example, the shock absorbing layer may be formed by attaching a sheet-shaped member made of a cured polyurethane moisture-curing adhesive to the lead frame 101 or the oversheet 20.

[0024] The effect of the impact absorbing layer according to this embodiment will be further described using experimental examples. An IC module was prepared in which an IC chip arranged on a lead frame was covered with a resin mold. In the experimental example, two different types of uncured polyurethane-based moisture-curing adhesives (Esdyne 9652 and Esdyne 9635C, manufactured by Sekisui Fuller Co., Ltd.) were applied to the lead frame and cured to form an impact absorbing layer, and four samples with different thicknesses of the impact absorbing layer (13 μm, 19 μm, 25 μm (Esdyne 9652), 39 μm (Esdyne 9635C)) were produced. The IC module with the impact absorbing layer and the coil antenna connected to it were sandwiched and laminated between polycarbonate sheets (DPI-AW, manufactured by Mitsubishi Chemical Co., Ltd.) intended as a core sheet and an oversheet to obtain an IC sheet. As a result, the thickness of the IC sheet including the resin sheets sandwiching the IC module was 370 to 400 μm. This was further sandwiched and laminated between polycarbonate sheets to obtain samples related to the four experimental examples with a thickness of about 800 μm. Furthermore, a sample (Comparative Example 1) was prepared in the same manner as described above using an IC module that did not have an impact absorbing layer, and a sample (Comparative Example 2) was prepared in which the thickness of the oversheet on the lead frame side was increased by 10 μm without forming an impact absorbing layer, obtaining a total of six types of samples.

[0025] The samples according to the experimental examples and comparative examples were placed stationary with the resin mold facing down, and a Charpy impact test was carried out under the following conditions. Hammer head: spherical (radius of curvature 0.5 mm) Hammer capacity: 0.5J Hammer drop height: 30mm Loading point: Center of IC chip Test object: Flat plate

[0026] After the shock test, we used a commercially available reader / writer to check whether communication with the IC chip was possible. All of the comparative examples were unable to communicate due to damage to the IC chip, but all of the experimental examples were able to communicate without any problems. When the cross section of the part where the impact was applied in each example was observed under magnification, it was found that the depth of the impact mark in the comparative example was about 60 μm, while in the experimental example it was about 50 μm, making the impact mark shallower. This suggests that the impact absorbing layer absorbs and disperses the impact, thereby preventing damage to the IC chip. From the above, it was demonstrated that the impact absorbing layer formed with a polyurethane-based moisture-curing adhesive is effective against impacts that cannot be fully mitigated by increasing the thickness of the overcoat layer, and can improve the impact performance of the IC sheet.

[0027] A second embodiment of the present invention will be described with reference to Figures 3 to 5. In the following description, configurations common to those already described will be given the same reference numerals and duplicated description will be omitted. 3 shows a schematic cross-sectional view of an IC sheet 1A according to this embodiment. The IC sheet 1A differs from the first embodiment in that, in addition to the shock absorbing layer 14 located on the lead frame 101 side, the IC sheet 1A also has a shock absorbing layer 14A (second shock absorbing layer) on the resin mold 102 side.

[0028] The shock absorbing layer 14A is formed of a polyurethane moisture-curing adhesive like the shock absorbing layer 14, but it is not essential that the two layers be the same adhesive, and any polyurethane moisture-curing adhesive will suffice.

[0029] As the inventors further investigated the matter, they found that when the impact absorbing layer 14 was present only on the lead frame 101 side, there were occasional cases in which the edge of the lead frame 101 curved toward the resin mold 102 during the lamination process of the over-sheet, and that depending on the degree of curvature, cracks were even formed in the over-sheet 20. One of the reasons for this phenomenon is believed to be that, due to the convex shape of IC module 100, the fluidity of the resin in the core sheet and oversheet that make up the IC sheet during the heat and pressure processing used to form the IC sheet causes IC module 100 to curve. If the entire IC sheet warps due to this phenomenon, this could cause communication problems in the completed IC sheet. The frequency of occurrence of the above phenomenon varies depending on the material of the oversheet and the lamination conditions, and it does not always occur, but it was thought that one of the causes of this phenomenon was that, while the center of lead frame 101 in a planar view is supported by resin mold 102 on the resin mold 102 side, there is no structure to support the areas located on the periphery.

[0030] The inventors have succeeded in suppressing this phenomenon by providing an impact absorbing layer 14A on the side of the resin mold 102. That is, by supporting the peripheral edge portion in plan view of the lead frame 101 with the impact absorbing layer 14A, it is possible to suppress deformation of the peripheral edge portion in plan view due to pressure during lamination processing of the oversheet, and it is possible to keep the lead frame 101 in a nearly flat state even in the completed IC sheet. Furthermore, since the IC chip 13 is protected from impact even on the resin mold 102 side, the impact resistance of the IC sheet can be further improved. In addition, resistance to static electricity, chemicals, and the like can also be improved.

[0031] The shock absorbing layer 14A can be formed by dropping a polyurethane moisture-curing adhesive, similar to the shock absorbing layer 14. The area of ​​the shock absorbing layer 14A in plan view may be larger than that of the shock absorbing layer 14, but there is no particular limitation on the form of dropping, and it can be appropriately determined, such as a line shape shown in FIG. 4(a), a dot shape shown in FIG. 4(b), or a cross shape shown in FIG. 4(c). The dropped adhesive is partially integrated by the pressure during lamination, and its shape in plan view is indefinite, but by appropriately setting the range of dropping, it can be a layer that favorably supports the peripheral part in plan view of the lead frame 101. There is no particular limitation on the state of the shock absorbing layer 14A, and it may be in any form, such as a liquid, gel, or sheet (solid).

[0032] The thickness of the impact absorbing layer 14A can be about 5 to 40 μm when completed through lamination processing. Within this numerical range, the relationship in thickness dimension between the impact absorbing layer 14A and the impact absorbing layer 14 can be either larger or equal, for example, the thickness ratio between the impact absorbing layer 14A and the impact absorbing layer 14 can be about 1:0.5 to 3.

[0033] On the resin mold 102 side, since the IC chip 13 is covered with the resin mold 102, the shock absorbing layer 14A does not necessarily have to be located on the resin mold 102. Therefore, for example, as shown in FIG. 5, the shock absorbing layer 14A may be formed on the lead frame 101 around the resin mold 102 in a plan view. In this way, the part where the IC module 100 is placed is made nearly flat, thereby reducing the warping of the IC sheet and reducing the occurrence of communication failures. In addition, since no additional layer is formed on the thick resin mold, there is an advantage that the thickness limit when the IC sheet is used for a passport or the like can be easily cleared, and the amount of adhesive used can be reduced. At this time, the periphery Li of the shock absorbing layer 14A does not necessarily have to be close to the resin mold 102, and may be slightly away. When the shock absorbing layer 14A is placed on the lead frame 101, it is preferable to cover about 50% of the lead frame 101 in a plan view.

[0034] As explained in the two embodiments, impact resistance can be ensured if the impact absorbing layer is on at least one side, and furthermore, curvature of the IC module can be suppressed and the IC sheet can be made smooth by applying the impact absorbing layer on both sides. As a result, the occurrence of communication failures in the completed IC sheet can be reduced and durability against static electricity, chemicals, etc. can be improved.

[0035] Although each embodiment of the present invention has been described above, the specific configuration is not limited to this embodiment, and configuration changes and combinations that do not depart from the gist of the present invention are also included.

[0036] For example, in the IC sheet according to the present invention, it is not essential that the IC chip is incorporated as an IC module, and therefore, the antenna formed on one side of the core sheet and the bare IC chip may be directly connected, and a part of the bare chip may be covered with the impact absorbing layer. 6 shows an example of an IC sheet using a bare chip as IC chip 13. There is no particular limitation on the manner of connection between IC chip 13 and the antenna, and either a direct connection between IC chip 13 and coil antenna 12 as shown in (a) or a manner in which pad 131 provided on IC chip 13 and coil antenna 12 are joined with solder 132 as shown in (b) may be adopted. Furthermore, a manner in which coil antenna 12A formed by etching a metal layer and IC chip 13 are connected with conductive adhesive 133 as shown in (c) may be adopted. Note that since bare chips are small, it is not necessary to provide holes in core sheet 30 if not necessary. In the above embodiment, the shock absorbing layers 14 and 14A preferably completely cover the IC chip 13, which is a bare chip, but preferably cover at least 50% or more of the area of ​​the IC chip 13 in a plan view of the planar IC sheet 1 in the normal direction. That is, the shock absorbing layers only need to cover the whole or part of the IC chip 13 in a plan view of the IC sheet 1. In addition, when covering the whole of the IC chip 13, the area of ​​the shock absorbing layer may be larger than that of the IC chip 13. In this case, it is easy to align the position of the shock absorbing layer on the IC chip. FIG. 6 shows an example in which the shock absorbing layers are provided on both sides, but it goes without saying that a single-sided configuration provided with only the shock absorbing layer 14 may also be used. [Explanation of symbols]

[0037] 1 IC sheet 12, 12A coil antenna 13 IC chip 14 Shock absorbing layer 14A Shock absorbing layer (second shock absorbing layer) 20 Overseat 30 Core Sheet 100 IC Module 101 Lead Frame 102 Resin mold

Claims

1. an IC module including a lead frame and an IC chip disposed on the lead frame, the IC chip being sealed with a resin mold; an antenna connected to the IC chip; Two core sheets are arranged to sandwich the antenna, one of which has a hole through which the lead frame can enter and the other has a hole through which the resin mold can enter; Two oversheets arranged so as to sandwich the core sheet; an impact absorbing layer formed by using a polyurethane moisture-curing adhesive and disposed between the lead frame and the oversheet facing the lead frame; Equipped with IC sheet.

2. In a plan view of the IC sheet, the impact absorbing layer covers 50% or more of the plan view area of ​​the IC chip. The IC sheet according to claim 1 .

3. The thickness is less than 450 μm. The IC sheet according to claim 1 .

4. The thickness of the impact absorbing layer is 80 μm or less. The IC sheet according to claim 1 .

5. The storage modulus of the impact absorbing layer at 25° C. is 20 megapascals or more and 100 megapascals or less. The IC sheet according to claim 1 .

6. The second impact absorbing layer is disposed between the core sheet having a hole through which the resin mold can enter and the oversheet facing the core sheet, and is formed using a polyurethane moisture-curing adhesive. The IC sheet according to claim 1 .

7. the second shock absorbing layer is disposed so as not to overlap the resin mold in a plan view of the IC sheet; The IC sheet according to claim 6.

8. An IC chip; an antenna connected to the IC chip; Two core sheets arranged to sandwich the antenna; Two oversheets arranged so as to sandwich the core sheet; an impact absorbing layer formed using a polyurethane moisture-curing adhesive and disposed between the core sheet and the oversheet; Equipped with IC sheet.

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