JPH07200414A - Method and substrate for prevention against decoding of storage contents - Google Patents

Abstract

PURPOSE:To prevent the storage contents of a memory and the contents of its relative integrated circuit from illegally be copied by decoding the contents of the memory by a 3rd person. CONSTITUTION:Electric conductors 16 for the power supply of an integrated circuit chip 20 are bent and formed in the entire mount area on the substrate 10. The integrated circuit chip 20 is mounted barely in the mount area while having its top side opposite the substrate top surface, and protected by molding its top with resin, etc. The integrated circuit chip 20 which is thus mounted can not have its top side seen directly and the moment the integrated circuit chip 20 tries to be peeled off the substrate 10, the power supply is cut off, so that the contents stored in the memory in the integrated circuit chip 20 are lost. Further, even if the memory contents tried to be analyzed by holing the substrate 10 without damaging the integrated circuit chip 20 from the reverse side of the substrate 10, the conductors 16 for the power supply are disconnected, so the storage contents are lost even in this case to prevent the memory contents from being decoded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a memory capable of retaining stored contents by supplying power, a method for preventing decipherment of stored contents for an integrated circuit incorporating such a memory, and a decipherment of stored contents. The present invention relates to a prevention substrate.

[0002]

2. Description of the Related Art In the game machine industry and the like, semiconductor integrated circuits conventionally used for popular games are analyzed by reverse engineering, and those with similar functions are copied and sold at a low price. The act of making unreasonable profits is widespread. In order to prevent such an action, an integrated circuit chip is provided with a memory such as SRAM that can hold the stored contents only while power is being supplied, and some ciphers are stored at the time of shipment to store the contents. Measures have been taken to prevent unauthorized copying by preventing the integrated circuit from operating unless it is read. This SRAM holds the stored contents by, for example, a power supply from a dedicated battery provided on the substrate, and when the memory is removed from the substrate, the power is cut off and the stored contents disappear. However, even if such a measure is taken, it is possible to dissolve the plastic package of the integrated circuit mounted on the substrate with a solvent and analyze the stored contents of the memory while maintaining the power supply to the integrated circuit. Finally, the contents of the semiconductor integrated circuit may be copied.

[0003]

In order to prevent such a situation, an unpackaged integrated circuit chip is directly mounted on a substrate so that the front side of the chip faces the substrate, and protection is performed from above. A so-called bare chip mounting method of covering with resin may be adopted. This method not only improves the degree of integration when mounted on the substrate, but also cannot see the front side of the chip mounted on the substrate, so the memory contents cannot be analyzed in this state. When the chip is removed from the substrate, the power supplied to the chip is inevitably cut off when the chip is released from the substrate and the stored contents are erased.
In the case of AM or the like, it is possible to prevent the content from being decrypted.

However, even when the method of bare chip mounting is adopted, a hole is made in the substrate from the back side of the substrate with a drill or the like so as not to damage the chip, and the state in which power is supplied to the chip is maintained. The contents can be read by looking at the front side of the memory. When the stored contents are analyzed in this way, it is still not possible to completely prevent copying of the stored contents of the memory and the associated integrated circuit.

The present invention has been made in view of the above circumstances, and provides a method for preventing decipherment of stored contents and a substrate for preventing decipherment of stored contents in which a third party cannot illegally decipher the contents of the memory. The purpose is.

[0006]

In order to solve the above-mentioned problems, the method for preventing decipherment of stored contents according to a first aspect of the present invention mounts a semiconductor device having storage means for holding stored contents when power is supplied. In the mounting area on the substrate, a conductive wire for supplying power to the semiconductor device is bent and wired over the entire mounting area, and the front side of the semiconductor device is mounted so as to face the surface of the substrate. To do.

In order to solve the above problems, the memory content decoding prevention substrate according to claim 2 is connected to a pad of the semiconductor device when the semiconductor device is mounted with the front side facing the substrate surface. The present invention is characterized in that a conducting wire having a contact point and for supplying power to the semiconductor device is bent and wired over the entire mounting region of the semiconductor device.

[0008]

According to the first aspect of the present invention, since the front side of the semiconductor device is mounted so as to face the substrate with the above configuration, the contents of the storage means cannot be analyzed only by looking at it from above the substrate. Also, by bending and wiring the power supply wire over the entire mounting area for mounting the semiconductor device on the board, the power supply wire is inevitably cut when a hole is drilled from the back side of the board. It Therefore, when the storage means built in the semiconductor device is an SRAM or the like, the stored contents disappear at that moment. As a result, it is possible to effectively prevent illegal decryption of the stored contents and the semiconductor device related thereto.

According to a second aspect of the present invention, by the above configuration,
SRAM in the mounting area where the power supply wire is bent and wired
If the storage means such as is mounted so that its front side (circuit formation surface or external connection area formation surface) faces the board surface, even if a hole is punched from the back of the board and the contents of the storage means are decoded, At the same time when the hole is made in the substrate, the power supply wire is cut and the stored content of the storage means is lost, so that the stored content and the semiconductor device related thereto can be effectively prevented from being illegally decoded.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view of an example of a substrate on which wiring for an integrated circuit chip is formed, and FIG. 2 is a perspective view showing how the integrated circuit chip is mounted on the substrate.

In the mounting region 12 shown by the broken line on the substrate 10 of FIG. 1, the integrated circuit chip 20 which is the semiconductor device shown in FIG. 2 is bare-chip mounted on the substrate with its front side facing. A large number of contacts (so-called bump mounting) connected to the pads of the integrated circuit chip 20 via bumps are formed on the inner peripheral edge of the mounting region 12. Further, wirings formed for connecting the integrated circuit chip to an external circuit are connected to the respective contacts as shown. It should be noted that the integrated circuit chip 20 will be described as having a built-in SRAM as a storage means.

By the way, one of the plurality of contacts 14 is a contact connected to the power supply pad 22 of the integrated circuit chip, and the conductive wire 16 connected to the contact 14 is a wiring for power supply. The conductive wire 16 is connected to a battery (not shown) dedicated to the integrated circuit chip 20 provided on the substrate 10. Also, unlike the other conductive wires, the conductive wire 16 is bent so as to reciprocate left and right inside the mounting area 12, passes through so as to cover almost the entire mounting area, and then is connected to the outside of the mounting area 12. Is formed.

As shown in FIG. 2, the integrated circuit 20 is mounted so that its front side faces the surface of the substrate, that is, it faces downward. After being mounted in this way, a resin or the like is molded on top of it for protection. In this way, the front side of the integrated circuit chip 20 on which the circuit pattern is formed cannot be seen, and therefore the stored contents of the SRAM cannot be analyzed as it is. Further, since the power supply pad 22 of the chip 20 is on the side facing the substrate, it is not possible to connect an external power supply to this power supply pad. In addition, melt the molded resin with a solvent etc.
When 0 is peeled from the substrate 10, the power supply pad 22 separates from the contact 14 at the moment when the chip 20 is peeled from the substrate, so that the power is cut off at that point and the stored contents of the SRAM are lost. Therefore, the chip 20 cannot be removed from the substrate 10 to analyze the contents of the SRAM.

By the way, conventionally, even when the chip 20 is mounted with the front side facing the substrate 10 in this way, a hole is drilled in the substrate from the back side of the substrate with a drill or the like so as not to damage the chip. Alternatively, illegal copying may be performed by a method of analyzing the stored contents of the SRAM while maintaining the state in which power is supplied to the chip by destroying only the substrate by some method. Therefore, in this embodiment, as shown in FIGS. 1 and 2, by forming the conductive wire 16 serving as the power supply wiring so as to cover the mounting region 12, the drilling is performed from the back side of the substrate 10 to see the front side of the chip 20 after mounting. When a hole is made with, for example, the conductive wire 16 is inevitably cut off, so that the contents stored in the SRAM disappear. Therefore, it is possible to effectively prevent the act of illegally copying the chip 20 by analyzing the stored contents of the SRAM.

The present invention is not limited to the above embodiment, and various modifications can be made within the scope of the invention. For example, the wiring method of the power supply conductor 16 inside the mounting area 12 is not limited to that shown in FIG. 1 or 2, and any method may be used as long as it is bent over the entire mounting area. The same effect can be achieved. For example, the power supply wire 16 may be formed in a spiral shape. Further, although the case where the memory is the SRAM has been described in the above embodiment, the present invention can be applied to any memory as long as the memory contents are held by the supply of power.

In this embodiment, only the case where the power supply pad 22 and all the other pads are formed on the same surface of the integrated circuit chip 20 has been described, but at least the power supply pad 22.
The other pads may be formed on other surfaces as long as the surface on which is formed is mounted so as to face the substrate 10.

[0017]

As described above, according to the present invention, the conductive wire for the power supply is formed by bending over the entire mounting area of the semiconductor device on the substrate, so that the front side of the semiconductor device is opposed to the substrate surface. When the chip is mounted on the bare chip, when the substrate is broken from the back side of the substrate, the conductive wire for the power supply is also cut off, the power supply to the semiconductor device is cut off, and the stored contents of the storage means in the semiconductor device disappear. Therefore,
It is possible to provide a method for preventing decipherment of stored content and a substrate for deciphering stored content that can effectively prevent the act of illegally copying the stored content or circuit connection of a semiconductor device.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing a part of a substrate which is an embodiment of the present invention.

FIG. 2 is a schematic perspective view showing a method of mounting an integrated circuit chip on a substrate which is an embodiment of the present invention.

[Explanation of symbols]

 10 substrate 12 mounting area 14 contacts 16 power supply wire 20 integrated circuit chip 22 power supply pad

Claims (2)

[Claims] 1. A conducting wire for supplying power to the semiconductor device is bent in a mounting area on a substrate for mounting a semiconductor device having a storage means for storing stored contents by supply of power, over the entire mounting area. A method for preventing decipherment of stored contents, comprising wiring and mounting the semiconductor device so that a front side of the semiconductor device faces a surface of the substrate. 2. A semiconductor device having a contact that is connected to a pad of the semiconductor device when the front side of the semiconductor device is mounted so as to face the substrate surface, and a conductive wire for supplying power to the semiconductor device. A board for preventing decoding of stored contents, which is formed by bending and wiring over the entire mounting area.