JP2000182016A - IC card - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To prevent an IC card from being damaged by a load acting in a form such as bending or spot pressing as much as possible. SOLUTION: In an IC card 1 having a three-layer structure of a circuit sheet 2, an intermediate sheet 3, and a cover sheet 4, a reinforcing plate 10 made of a stainless steel plate is provided on an upper surface of a sealing member 7 of a semiconductor chip 6. A bending test and a point-push test are performed based on a load form that works well when the IC card 1 is put to practical use, and a finite element analysis simulating the test is performed. A relational expression with the thickness T of the semiconductor chip 6 is obtained, and the thickness t of the reinforcing plate 9 is set in a range satisfying the relational expression. Thereby, damage of the semiconductor chip 6 can be prevented as much as possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an IC card having a semiconductor chip having functions such as a memory and a CPU.
In particular, the present invention relates to a device for preventing breakage of a semiconductor chip during actual use.

[0002]

A cash card, a credit card, and the like, which are widely used at present, are obtained by applying a magnetic stripe to a plastic card and reading information recorded on the magnetic stripe. Such a magnetic recording method has problems such that information is easily read by a third party and the amount of recordable information is small.

Therefore, in recent years, an IC card in which a semiconductor chip having functions such as a memory and a CPU is mounted on a card-like base has been developed and has already been put to practical use. This IC card usually has a circuit sheet on which a semiconductor chip is mounted by forming a circuit pattern, an intermediate sheet having a hollow hole for accommodating the semiconductor chip and mounted on the circuit sheet, and an IC card mounted on the intermediate sheet. And a cover sheet having a three-layer structure.

In an IC card having such a structure, the semiconductor chip is weak against bending force applied to the semiconductor chip, and the semiconductor chip may be broken and become unusable. To solve this problem and improve the bending resistance of the semiconductor chip, for example, Japanese Patent Application Laid-Open Nos.
There is a technique disclosed in Japanese Patent No. 263082.

[0005] The IC card disclosed in Japanese Patent Application Laid-Open No. 9-156265 has a semiconductor chip mounted on a circuit board.
A spacer provided with a hollow for accommodating a semiconductor chip is adhered on a circuit board, and a reinforcing plate is formed on the spacer as a reinforcing plate having a thickness slightly larger than the above-mentioned hollow.
A stainless plate having a thickness of about 0 μm is disposed directly above the semiconductor chip, and a cover film is further adhered thereon. Also, Japanese Patent Application Laid-Open No. 9-26308
In the IC card disclosed in Japanese Patent Publication No. 2, a stainless steel plate having a thickness of about 20 μm is adhered to at least one surface of a semiconductor chip as a reinforcing plate, and the semiconductor chip is embedded in a sheet-like intermediate layer. And a sheet bonded to the sheet.

By the way, when an IC card is actually used, I
Loads are applied to the C card in various forms. Generally, the IC card is roughly classified into two forms: a bending load in which the IC card is bent or twisted in an arc shape, and a so-called spot load in which a partial pressing force is applied. . With respect to such a load, by arranging the reinforcing plate on one side of the semiconductor chip, the rigidity of the semiconductor chip can be substantially increased, so that damage of the semiconductor chip can be prevented.

However, according to the results of experiments conducted by the present inventor and the like, according to the conventional semiconductor chip reinforcing technique, that is, the reinforcing technique of disposing a reinforcing plate on one side of a semiconductor chip, the thickness of the reinforcing plate and the thickness of the semiconductor chip are reduced. Depending on the relationship with the thickness, when a load is applied in the form of bending, spot pressing, or the like, the generated stress of the semiconductor chip may be greater than that without the reinforcing plate, and it is not necessarily possible to prevent damage to the semiconductor chip. It turns out that it is not limited.

The present invention has been made in view of the above circumstances, and an object of the present invention is to set a thickness of a reinforcing plate in a predetermined range in relation to a thickness of a semiconductor chip to bend, push, etc. Another object of the present invention is to provide an IC card capable of withstanding a load acting in the form described above and preventing damage to a semiconductor chip as much as possible.

[0009]

Means for Solving the Problems The inventor of the present invention changed the combination of the thickness of the semiconductor chip and the thickness of the reinforcing plate in various ways, and performed a finite element analysis simulating the test when performing a bending test and a point pressing test. The internal stress of the semiconductor chip was clarified, and the semiconductor chip was inspected for damage. From this test result, the relationship between the thickness of the reinforcing plate and the thickness of the semiconductor chip that can withstand loads such as bending and spot pressing and prevent damage to the semiconductor chip was determined.

Specifically, a bending test corresponding to a case where a user sits down on a chair or the like with an IC card inserted in the back pocket of the pants, and a push with a relatively sharp projection such as a tip of a ballpoint pen. A sharp point pressing test corresponding to the case where the IC card put in the wallet or the like is pressed by a button of the clothes or the wallet or the like, and the semiconductor chip is not damaged. The thickness of the reinforcing plate was determined as a relational expression with the thickness of the semiconductor chip.

The following equation (1) shows that the thickness t of the reinforcing plate that does not break the semiconductor chip is determined by the thickness T of the semiconductor chip from the results of the bending test and the sharp spot pressing test.
It was obtained in relation to

(Equation 3)

The following equation (2) is a bending test,
The thickness t of the reinforcing plate that does not destroy the semiconductor chip was determined in relation to the thickness T of the semiconductor chip from the results of the sharp point pressing test and the dull point pressing test.

(Equation 4)

According to the IC card of the first aspect, since the thickness t of the reinforcing plate is set in the range shown by the above equation (1),
Excessive stress may be applied to the semiconductor chip when the user sits down on a chair or the like with the IC card inserted in the back pocket of the pants, or when pressed by a relatively sharp protrusion such as the tip of a ballpoint pen. The semiconductor chip can be prevented from acting, and damage to the semiconductor chip can be effectively prevented. According to the IC card of the second aspect, since the thickness t of the reinforcing plate is set in the range shown by the above equation (2), the reinforcing plate is pressed by a not so sharp protrusion such as a button of clothes or a wallet. In addition, damage to the semiconductor chip can be effectively prevented.

The function of the reinforcing plate is to substantially increase the rigidity of the semiconductor chip to prevent the semiconductor chip from being damaged. For this reason, a predetermined rigidity cannot be obtained unless the reinforcing plate is made of ordinary plastic unless it is considerably thick. This results in an increase in the thickness of the entire IC card. Therefore, in the IC card according to the third aspect, the Young's modulus of the reinforcing plate is set to 100 to 300 GPa. If the material has a Young's modulus of such a value, the rigidity necessary for reinforcing the semiconductor chip can be obtained even if it is thin, and I
The C card can be formed in an appropriate thickness that is easy to handle.

Further, assuming that the reinforcing plate is disposed on the circuit board side of the semiconductor chip, in this case, it is necessary to electrically connect the semiconductor chip and the circuit board. It must be provided on the surface opposite to the semiconductor chip mounting surface. However, this would require another sheet to cover the stiffener,
This leads to an increase in the thickness of the entire IC card. I of claim 4
In the C card, since the reinforcing plate is disposed on the opposite side of the circuit board from the side on which the semiconductor chip is mounted, the reinforcing plate can be hidden by a casing for protecting the semiconductor chip, and the thickness of the IC card can be reduced. Can contribute.

In order to reduce the thickness of the IC card to an easy-to-handle thickness, the thickness of the semiconductor chip is set to 5
It is preferably set to 0 to 150 μm.
The total thickness of the card is 40
It is preferably from 0 to 900 μm.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. First, as shown in FIGS. 1 and 2, an IC card 1 includes a circuit sheet 2 as a circuit board.
, An intermediate sheet 3 as an intermediate adhesive layer, and a cover sheet 4.

The circuit sheet 2 is a sheet made of plastic, for example, a polyester-based plastic, specifically, PET (polyethylene terephthalate). On one surface of the circuit sheet 2, a coil-shaped circuit pattern 5 as a conductor circuit is formed, and a semiconductor chip 6 connected to the circuit pattern 5 is mounted.
The semiconductor chip 6 is molded by a sealing member 7. The sealing member 7 is a relatively hard material made of, for example, epoxy-based plastic, and a casing 8 for protecting the semiconductor chip 6 is constituted by the sealing member 7, the intermediate sheet 3 and the cover sheet 4. .

In this embodiment, the coil-shaped circuit pattern 5 is formed by a screen printing means using a conductive paste, for example, a polyester-based silver paste, and the semiconductor chip 6 is formed by, for example, an anisotropic conductive adhesive. 9 is flip-chip mounted. The circuit pattern 5 functions as an element for transmitting / receiving a signal to / from an external device, in this embodiment, an antenna for transmitting / receiving a radio signal. The circuit pattern 5 is configured to be obtained by a radio signal received from an external device.

The intermediate sheet 3 is made of a plastic material having a heat-melting property such that the intermediate sheet 3 becomes molten when heated and becomes fluid, for example, a sheet formed of a polyester-based hot melt adhesive. This intermediate sheet 3
Has a function of protecting the circuit pattern 5, the semiconductor chip 6, and the like, and also having a function of bonding itself to the circuit sheet 2 and the cover sheet 4, and covers the circuit pattern 5, the semiconductor chip 6, and the like without gaps. The cover sheet 4
Also has the function of protecting the relatively soft intermediate sheet 3,
For example, like the circuit sheet 2, it is made of a PET sheet.

In order to manufacture such an IC card 1 having a three-layer structure, first, a semiconductor chip 6 is mounted on the circuit sheet 2 and then the semiconductor chip 6 is molded with an epoxy-based plastic to form the sealing member 7. To form The epoxy-based plastic has fluidity at room temperature before curing, so that the fluidity covers the semiconductor chip 6 without gaps.

After the semiconductor chip 6 is molded with the sealing member 7, the intermediate sheet 3 and the cover sheet 4 are sequentially stacked on the circuit sheet 2, and the whole is thermocompression-bonded by a hot press device (not shown). Then, the hot-melt adhesive constituting the intermediate sheet 3 is heated and melted and becomes fluid, so that the molten hot-melt adhesive covers the circuit pattern 5 and the sealing member 7 without gaps. . At the same time, the intermediate sheet 3 is formed so as to have a uniform thickness by applying pressure from both the upper and lower sides, and adheres the circuit sheet 2 and the cover sheet 4. Then, the intermediate sheet 3 is cooled by the subsequent cooling.
Is solidified, and an IC card 1 having a three-layer structure including the circuit sheet 2, the intermediate sheet 3, and the cover sheet 4 is manufactured as described above.

In the IC card 1 as described above, the circuit sheet 2 and the cover sheet 4 are formed of PET, and the intermediate sheet 3 is formed of a polyester hot melt adhesive. Therefore, when a bending force acts, the IC card 1 bends flexibly with elasticity.

When the IC card 1 is bent, a bending force acts on the semiconductor chip 6 and the semiconductor chip 6 may be broken. Therefore, the semiconductor chip 6 is reinforced to substantially increase its rigidity. , A reinforcing plate 10 is provided. The reinforcing plate 10 is formed to have substantially the same size as the sealing member 7, and is disposed on the upper surface of the sealing member 7 in a step after the semiconductor chip 6 is sealed by the sealing member 7.
In this case, the reinforcing plate 10 is disposed so that the center thereof substantially matches the center of the semiconductor chip 6. Thereafter, the circuit sheet 2, the intermediate sheet 3, and the cover sheet 4 are thermocompression-bonded as described above.
When the hot melt adhesive constituting the above is in a molten state, the hot melt adhesive is completely covered by the hot melt adhesive.

Here, the mirror surface 6a side of the semiconductor chip 6 means the upper surface side in FIG. That is, FIG.
The integrated circuit is formed on the lower surface of the upper and lower surfaces of the semiconductor chip 6 on the circuit sheet 2 side, and the upper surface is a mirror surface that has been back-ground when the semiconductor chip 6 is a wafer. For this reason, the upper surface of the semiconductor chip 6 is referred to as a mirror surface, and the lower surface is referred to as a circuit surface.

The reinforcing plate 10 has a Young's modulus of 100 to 300 GPa (giga.
Pascal) material, for example, a stainless steel plate. The reinforcing effect of the reinforcing plate 10 is generally greater as the thickness is larger. However, in a load form such as bending or spot pressing that often appears in actual use, even if the reinforcing plate 10 is provided, the stress acting on the semiconductor chip 6 may be increased depending on the relationship with the thickness of the semiconductor chip 6.

Then, the present inventor conducted a bending test and two types of point pressing tests using the IC card 1 as described above,
The thickness of the reinforcing plate 10 for preventing the semiconductor chip 6 from being damaged was determined in relation to the thickness of the semiconductor chip 6. In the bending test, as shown in FIG. 8, the IC card 1 is placed on a mandrel 11 having a radius of 40 mm so that the mirror surface 6a side of the semiconductor chip 6 faces down, and the entire IC card 1 is clamped in an arc shape. The tool 12 is pressurized and bent into an arc shape along the cylindrical outer surface of the mandrel 10, and the stress acting on the semiconductor chip 6 is clarified by finite element analysis simulating a test, and the presence or absence of breakage of the semiconductor chip 6 is determined. It is to be inspected.

The point pressing test includes a sharp point pressing test shown in FIG. 9 and a dull point pressing test shown in FIG.
The portion of the C card 1 where the semiconductor chip 6 (reinforcement plate 10) is placed is pressed by small-diameter hemispherical indenters 13 and 14 so that the semiconductor chip 6
Is clarified by finite element analysis simulating a test, and the presence or absence of breakage of the semiconductor chip 6 is inspected. In this test, the IC card 1 is placed on a mirror plate 6 of a semiconductor chip 6 on a rubber plate 15 having a thickness of 20 mm.
It is placed so that the a side faces upward. Then, in the sharp spot pressing test, the hemispherical indenter 13 having a radius of 1.5 mm was
(Newton), and in the dull spot pressing test, the radius is 1
A 0 mm hemispherical indenter 14 is pressed with 17N.

In the above bending test, the I
The reason why the C card 1 is placed so that the mirror surface 6a side of the semiconductor chip 6 faces down, and the IC card 1 is placed on the rubber plate 15 so that the mirror surface 6a side of the semiconductor chip 6 faces up in the spot pressing test is as follows. It is as follows. That is, the IC card 1 is pressed by the holding jig 12 or the hemispherical indenter 13 is pressed.
When the IC card 1 is pressed at 4, the IC card 1 bends so that the circuit sheet 2 side becomes convex. At this time, the neutral axis of the bending of the IC card 1 is, for example, as shown by a two-dot chain line ρ in FIG.
It is thought that it exists on the a side. Then, a compressive force acts on the mirror surface 6a side of the semiconductor chip 6 and a tensile force acts on the circuit surface 6b.

The mirror surface 6a of the semiconductor chip 6 has a high strength with the single crystal of the wafer as it is, but the circuit surface 6b has impurities added for forming an integrated circuit.
It is uneven in shape and weak in strength.
Therefore, even when the same bending stress is applied, the semiconductor chip 6 is more likely to be damaged when the circuit surface 6b side becomes convex and a tensile force is applied. In consideration of the above, in the bending test and the point pressing test, the IC card 1 is set so that the circuit surface 6b side becomes convex when the IC card 1 is bent.

Such a bending test, a sharp point pressing test, or a dull point pressing test corresponds to a typical load form in actual use of the IC card 1. That is, various loads act on the IC card 1 during its actual use. In many cases, when the user sits down on a chair with the IC card 1 placed in the back pocket of the pants, the IC card 1 An IC card 1 such as an object like a ballpoint pen hits 1
When a pressing force is applied to a very narrow place, or when the button of the wallet hits the IC card 1 in the wallet,
This is a case where a pressing force is applied to a slightly wide portion of the IC card 1.

Assuming such a typical load form, I
The bending test shown in Fig. 8 is performed for a case where the purse containing the C card 1 is placed in the back pocket of the pants and the chair is lowered, and a pressing force is applied to a very narrow part of the IC card 1. 9 was subjected to a sharp spot pressing test shown in FIG.
A dull spot test shown in FIG. 10 was performed for a case in which a pressing force was applied to a slightly wider portion of the C card 1.

FIG. 5 shows the results of the bending test, FIG. 6 shows the results of the sharp point pressing test, and FIG. 7 shows the results of the dull point pressing test. Here, (a) of each figure shows the maximum stress of the circuit surface 6b,
(B) shows the maximum stress acting on the end (four sides) of the semiconductor chip 6, and (a) and (b) show
The stress range in which the semiconductor chip 6 was not damaged is indicated by hatching. The reason for measuring the maximum stress at the end of the semiconductor chip 6 is that the semiconductor chip 6 is obtained by dicing from a wafer. Therefore, the stress acting on the portion is clarified by finite element analysis simulating a test, and the presence or absence of breakage is inspected.

From the two test results of the bending test and the sharp spot pressing test, in both tests, the range of the thickness t of the reinforcing plate 10 in which the semiconductor chip 6 was not damaged was defined as the range of the thickness T of the semiconductor chip 6. Ask for a relationship. This range is, in actual use, I
Reinforcing plate with which the semiconductor chip 6 is hardly damaged even when the user sits down on a chair with the wallet containing the C card 1 in the back pocket of the pants or applies a pressing force to a very narrow part of the IC card 1 A range of 10 thicknesses.

The range of the thickness t of the reinforcing plate 10 in which the semiconductor chip 6 does not break in the bending test and the sharp spot pressing test is shown by hatching in FIG. In FIG. 3, the curve C1
(The same as the curve C1 with the maximum stress of 350 MPa in FIG. 5B) is a line indicating the boundary of the presence or absence of breakage of the semiconductor chip 6. When the equation representing the curve C1 is obtained by least square approximation, 1) It becomes like the right side of the equation. Therefore, if the thickness t of the reinforcing plate 10 is set within the range of the following equation (1),
At the time of actual use, while sitting in the back pocket of the trousers with the wallet containing the IC card 1 sitting down on the chair,
Even if a pressing force is applied to a very narrow portion, the semiconductor chip 6 can be prevented from being damaged.

(Equation 5)

From the three test results of the bending test, the sharp point pressing test, and the dull point pressing test, a range in which the semiconductor chip 6 is not damaged in any of the tests is determined in relation to the thickness of the semiconductor chip 6. This range is that, in actual use, the user can sit down on the chair with the wallet containing the IC card 1 in the back pocket of the pants, apply a pressing force to a very narrow part of the IC card 1, This is the range of the thickness of the reinforcing plate 10 in which the semiconductor chip 6 is hardly damaged even if a pressing force is applied to a wide portion.

The range of the thickness of the reinforcing plate 10 at which the semiconductor chip 6 hardly breaks is shown by oblique lines in FIG. FIG.
In the curve C2 (the maximum stress of 380MP in FIG. 6A)
a) is a line indicating the boundary of whether or not the semiconductor chip 6 is damaged.
When it is obtained by the power approximation, it is as shown on the right side of the following equation (2). Therefore, if the thickness t of the reinforcing plate 10 is set in the range of the following expression (2), during actual use, the user can sit down on the chair with the wallet containing the IC card 1 in the back pocket of the pants, or Even if a pressing force is applied to a very narrow portion of the card 1 or a pressing force is applied to a relatively wide portion of the IC card 1, the semiconductor chip 6 can be hardly damaged.

[0038]

(Equation 6)

Here, an example of specific dimensions of the IC card 1 will be described below. [Specific Example 1] Both the circuit sheet 2 and the cover sheet 4 have a thickness of 125 μm. The total thickness of the IC card 1 after bonding the two sheets 2 and 4 with the intermediate sheet 3 is 605 μm. The thickness of the semiconductor chip 6 is 100 μm. [Specific Example 2] The thickness of the circuit sheet 2 and the cover sheet 4 are both 100 μm. The total thickness of the IC card 1 after bonding both sheets 2 and 4 with the intermediate sheet 3 is 627 μm. The thickness of the semiconductor chip 6 is 150 μm. The thickness of the plate 10 is 50 μm. Incidentally, the specific example 1 satisfies the expression (1), and the specific example 2 satisfies both the expressions (1) and (2).

The total thickness of the IC card 1 is not limited to the specific examples 1 and 2. However, considering the flexibility and ease of use of the IC card 1, the total thickness of the IC card 1 is 40
It is preferable to set the thickness in the range of 0 to 900 μm. Also,
The thickness T of the semiconductor chip 6 is 10 times the total thickness of the IC card 1.
It is preferable that the thickness of the reinforcing plate 10 is set in the range of 8 to 20% of the total thickness of the IC card 1.

When making the IC card 1 as thin as possible,
Since there is a limit in reducing the thickness of the circuit sheet 2 and the cover sheet 4, it is preferable to reduce the thickness of the intermediate sheet 13 and thus the semiconductor chip 6. In this case, the preferable thickness of the semiconductor chip 6 is 50 to 150 μm.

The present invention is not limited to the embodiment described above and shown in the drawings, but can be extended or modified as follows. The total thickness of the IC card 1 may be less than 400 μm, or may exceed 900 μm. The thickness of the semiconductor chip 6 is not limited to 50 to 150 μm.
To make the card 1 extremely thin, for example, 0.5 μm
If the thickness is not considered, a thickness of, for example, about 200 μm may be used. The reinforcing plate 10 is not limited to stainless steel, but may be copper, aluminum, or the like. However, in order to substantially increase the rigidity of the semiconductor chip 6 to prevent breakage, the Young's modulus is 100 to 100%.
It is preferable to select from a material of 300 GPa, and if it is within the range, it may be made of plastic. The IC card 1 is composed of a circuit sheet 2, an intermediate sheet 3, and a cover sheet 4.
It is not limited to a layered structure. The disposition position of the reinforcing plate 10 may be on the side opposite to the mounting surface of the circuit sheet 2 on which the semiconductor chip 6 is mounted. In this case, it is preferable to attach the sheet to the circuit sheet 2 so as to hide the reinforcing plate 10. The sealing member 7 may not be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an IC card showing one embodiment of the present invention.

FIG. 2 is an exploded perspective view of an IC card.

FIG. 3 is a first graph showing a curve for obtaining an equation for the thickness of a reinforcing plate.

FIG. 4 is a second graph showing a curve for obtaining a formula for the thickness of the reinforcing plate.

FIG. 5 is a graph showing a result of a bending test.

FIG. 6 is a graph showing the results of a sharp spot pressing test.

FIG. 7 is a graph showing the results of a dull spot pressing test.

FIG. 8 shows a bending test.

FIG. 9 is a view showing a sharp spot pressing test;

FIG. 10 is a diagram showing a dull spot pressing test.

[Explanation of symbols]

In the figure, 1 is an IC card, 2 is a circuit sheet, 3 is an intermediate sheet, 4 is a cover sheet, 6 is a semiconductor chip, 8 is a casing, and 10 is a reinforcing plate.

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 2C005 MA10 NA08 NA31 NB37 PA18 PA26 PA27 RA04 RA11 TA22 5B035 AA08 BA05 BA09 BB09 BC00 CA03 CA12 CA23

Claims (6)

[Claims] 1. A semiconductor device comprising: a circuit board having a conductor circuit; a semiconductor chip mounted on the circuit board; a reinforcing plate for reinforcing the semiconductor chip; and a casing for protecting the semiconductor chip. An IC card characterized in that, when T is the thickness of the reinforcing plate and t is the thickness of the reinforcing plate, the thickness t of the reinforcing plate is set to satisfy the following expression. (Equation 1) 2. A semiconductor device comprising: a circuit board having a conductor circuit; a semiconductor chip mounted on the circuit board; a reinforcing plate for reinforcing the semiconductor chip; and a casing for protecting the semiconductor chip. An IC card characterized in that, when T is the thickness of the reinforcing plate and t is the thickness of the reinforcing plate, the thickness t of the reinforcing plate is set to satisfy the following expression. (Equation 2) 3. The reinforcing plate has a Young's modulus of 100 to 30.
The IC card according to claim 1, wherein the IC card is 0 GPa. 4. The IC according to claim 1, wherein the reinforcing plate is disposed on a side of the circuit board opposite to a side on which the semiconductor chip is mounted. card. 5. The semiconductor chip has a thickness of 50 to 15
The IC card according to any one of claims 1 to 4, wherein the IC card is set to 0 µm. 6. The IC card according to claim 1, wherein the total thickness is 400 to 900 μm.