JPH10335571A - Memory module and memory system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a memory module and a memory system in which a memory chip can be cooled efficiently. SOLUTION: On the surface of a memory module 10 for mounting an SO- DIMM(small outline dual in-line memory module) substrate 11, a plurality of grooves 14 is formed in nearly parallel with the shorter side of the module 10 and heat radiating members 15 which diffuse the heat generated from a bare chip for memory throughout a memory system 20 are attached to the grooves 14. Since the heat generated from the bare chip for memory is diffused throughout the memory system 20, the radiating area of the heat is expanded. Therefore, the heat radiating efficiency of the memory module 10 to the outside can be improved and the temperature rise of the bare chip for memory can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a memory module and a memory system used for a personal computer (personal computer) or the like.

[0002]

2. Description of the Related Art Generally, a memory bare chip and a processor bare chip cut out of a semiconductor wafer are mounted on a printed circuit board or the like in a packaged state. However, since the external dimensions of the package are considerably larger than the size of various bare chips, there are certain restrictions on the number of memory packages and the like that can be mounted on a printed circuit board or the like.

On the other hand, recently, a multi-chip module (MCM) in which a plurality of bare chips are mounted on a substrate having substantially the same size as a packaging substrate is becoming widespread. By using this multi-chip module, it is possible to reduce the mounting area in size and weight, to achieve high-density wiring, to ensure high performance and high speed by bare chip mounting, and to ensure high reliability.

[0004]

When various types of bare chips are mounted on a module substrate and operated, the temperature of the bare chips rises because the chips themselves generate heat. This temperature rise becomes larger as the degree of integration of bare chips increases at the same operating voltage and operating speed. Further, in the above-described multi-chip module, since a plurality of bare chips are mounted at a high density on a module substrate having a small area, a heat radiation area is small, and heat generated from each bare chip is efficiently released to a printed wiring board or the like. Is difficult. In particular, various types of memory chips such as DRAMs are rapidly increasing in capacity, and the amount of generated heat is also rapidly increased with this. Therefore, it is necessary to devise a method of efficiently dissipating heat and cooling the memory chips.

[0005] The present invention has been made in view of the above points, and an object of the present invention is to provide a memory module and a memory system that can efficiently cool a memory chip.

[0006]

In order to solve the above-mentioned problems, a memory module according to the present invention is configured as a multi-chip module, and includes a plurality of memories cut out from a semiconductor wafer on one surface of a module substrate. Chip is mounted. The other surface is a surface for mounting on a printed wiring board or the like, and at least one of attachment of a heat radiating member and formation of a concave portion is performed on this surface. When the heat radiating member is attached, the heat generated from the memory chip is diffused by the heat radiating member to the entire memory module, and the heat radiating area is enlarged, so that the temperature rise of the memory chip is suppressed. In addition, when the concave portion is formed, an increase in the heat dissipation area due to the formation of the concave portion and cooling by the air flowing through the concave portion suppress the temperature rise of the memory chip. In this way, it is possible to suppress a rise in temperature that causes unstable operation of the memory chip.

Further, a memory system according to the present invention comprises a memory module on which a plurality of memory chips are mounted and a printed wiring board on which the memory module is mounted. The surface opposite to the mounting surface is a contact surface (mounting surface) with the printed wiring board. At least one of attachment of a heat radiating member and formation of a concave portion is performed on one or both of the contact surface on the memory module side and the contact surface on the printed wiring board side. When the heat radiating member is attached, the heat generated from the memory chip is diffused from the memory module to the wide area of the memory system by the heat radiating member, and the heat radiating area is enlarged, so that the temperature rise of the memory chip is suppressed. In the case where the concave portion is formed, an increase in the heat dissipation area due to the formation of the concave portion and cooling by the air flowing through the concave portion suppress the temperature rise of the memory chip. In this way, it is possible to suppress a rise in temperature that causes unstable operation of the memory chip.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a memory module and a memory system according to an embodiment of the present invention will be described.
This will be specifically described with reference to the drawings.

FIG. 1 is a plan view schematically showing one surface of a memory module according to an embodiment, and FIG. 2 is a sectional view taken along line AA 'of FIG. As shown in these drawings, a memory module 10 is configured such that four memory bare chips 1 as memory chips individually cut out from a semiconductor wafer are mounted on a module substrate 2 by COB (Chip).
On Board) Implemented. Each memory bare chip 1 is, for example, a DRAM having a memory capacity of 4M × 4 bits. Each of the memory bare chips 1 has a rectangular shape, and pads 3 are formed in a line in the center along the long side. Have been.

On the other hand, the module substrate 2 is made of a SO
−DIMM (Small Outline Dual Inline Memory Modul
e) It has an external dimension that can be mounted on a board, and a plurality of pads 4 are formed in a row near the center of the module board 2 along the longitudinal direction. Two bare chips 1 for memory are mounted on both sides of these pads 4,
The direction in which the pads 4 of the module substrate 2 are arranged is substantially parallel to the direction in which the pads 3 of each bare chip 1 for memory are arranged. In other words, a plurality of pads 4 are formed on the module substrate 2 so as to be parallel to the respective pads 3 between the two memory bare chips 1 arranged such that the long sides are adjacent to each other. .

The pads 4 of the module substrate 2 and the pads 3 of the bare memory chip 1 are connected by bonding wires 5 respectively. The pad 4 includes a pad to which two bonding wires 5 are connected and a pad to which one bonding wire is connected. For terminals commonly connected to a plurality of memory bare chips 1 such as address terminals of the memory bare chip 1, the pads 4 can be shared by connecting a plurality of bonding wires 5 to the pads 4 on the module substrate 2. I'm trying.

As described above, for some of the pads 4,
Since a plurality of bonding wires 5 are connected, the total number of pads 4 can be smaller than the total number of pads 3 of all memory bare chips 1. Further, by connecting two bonding wires 5 to some of the pads 4, the two bonding wires 5 can be connected to each other at the same time through the common pad 4.
The amount of wiring inside can be reduced. For example, when the module substrate 2 is configured using a multilayer substrate, the number of layers of the substrate can be reduced, and the cost of the memory module 10 can be reduced.

Further, since the pads 4 on the module substrate 2 are concentrated between the two memory bare chips 1 arranged such that the long sides thereof are adjacent to each other, the pads 4 are separately provided outside the respective memory bare chips 1. The area occupied by the entire pad 4 can be reduced as compared with the case where the pad 4 is formed in the first step, and the memory module 10 can be reduced in size and mounted at a high density.

The memory module 10 of the present embodiment
As shown in FIG. 2, the upper surface of the wire-bonded memory bare chip 1 is covered with a resin 6 to prevent disconnection and the like. If the resin 6 is formed thick, the height of the memory module 10 becomes too high. Therefore, a sealing frame 7 having a predetermined height is attached near the outer periphery of the module substrate 2, and the resin 6 is poured into the sealing frame 7. The resin thickness matches the height of the sealing frame 7. Thereby, variation in the height of the memory module 10 can be reliably suppressed.

The memory module 10 according to the present embodiment
Is mounted on various substrates such as an SO-DIMM substrate described later by a so-called LCC (Leadless Chip Carrier) method. FIG. 3 shows the memory module 1 shown in FIG.
FIG. As shown in the figure, a plurality of external connection terminals 8 formed in a concave shape are provided on the outer surface of the module substrate 2, and these external connection terminals 8 are formed on the surface or inside of the module substrate 2. Pad 4 on the surface of module substrate 2 via pattern 9
Is electrically connected to Also, by pouring solder into the recesses of these external connection terminals 8, the SO-DIM
At the same time as the electrical connection with the M substrate and the like, mechanical fixing is also performed.

When the memory bare chip 1 operates, heat is generated by the movement of the carrier. In the memory module 10, since a plurality of memory bare chips 1 are mounted at a high density, the interval between the memory bare chips 1 is narrow, the heat radiation area for generated heat is small, and the cooling efficiency is poor. The temperature of the bare chip 1 rises. The surface of the module substrate 2 opposite to the surface on which the memory bare chip 1 is mounted is in close contact with the SO-DIMM substrate or the like when mounted on a printed wiring board such as an SO-DIMM substrate. For this reason, in the memory module 10 of the present embodiment, the heat generated in each memory bare chip 1 is diffused over almost the entire surface of the memory module 10 by attaching a heat radiating member to one surface facing the printed wiring board. Thus, the heat radiation effect is enhanced, and each memory bare chip 1 is cooled.

FIG. 4 is a sectional view taken along line BB 'of FIG.
FIG. 5 is a diagram schematically showing a mounting surface of the memory module 10 on a printed wiring board. As shown in these figures, a plurality of grooves 14 are formed on the surface of the module substrate 2 opposite to the surface on which the memory bare chip 1 is mounted. Each groove 14 has a predetermined shape, for example, a substantially semicircular cross section, and is formed substantially parallel to the short side of the module substrate 2 from one long side of the module substrate 2 to the other long side opposite thereto. ing. By making the cross section semi-circular, heat absorption from the surrounding module substrate 2 can be improved. The plurality of grooves 14 are formed in a range that does not contact the external connection terminals 8 attached to the module substrate 2.

The grooves 14 receive heat locally generated by the memory bare chip 1 in the memory module 10.
A heat dissipating member 15 for dispersing substantially over the entire surface is attached. Since it is necessary to efficiently dissipate heat, it is desirable to use a metal material having good heat conductivity such as copper for the heat dissipating member 15. Further, the heat radiating member 15 may be embedded in the groove 14 without any gap, or may be mounted only on the surface of the groove 14. In particular, as shown in FIG. 6, by making the heat radiation member 15 longer than the short side length of the module substrate 2, when the memory module 10 is mounted on the printed wiring board, a part of the heat radiation member 15 becomes outside. Since the exposed heat dissipating member 15 functions as a cooling fin, the cooling efficiency can be further improved.

As described above, in the memory module 10 of the present embodiment, the plurality of grooves 14 are formed on one surface of the module substrate 2 and on the surface to be mounted on another printed wiring board. A heat radiating member 15 is attached to 14. When each memory bare chip 1 mounted on the memory module 10 generates heat, this heat is transmitted to the heat dissipating members 15 approaching each memory bare chip 1, so that almost the entire surface of the memory module 10 on which each heat dissipating member 15 is formed. , And the local temperature rise near each memory bare chip 1 can be reduced. Further, since each heat radiating member 15 is formed over substantially the entire surface of the memory module 10 and the heat radiating area is enlarged, each heat radiating member 15 is formed.
Heat is efficiently transmitted to other printed wiring boards with which it is in direct contact, or heat is efficiently radiated from each heat radiation member 15 to the air around the memory module 10 via the module substrate 2 and the resin 6. , Bare chip for memory 1
Is cooled. For this reason, the temperature rise of each memory bare chip 1 can be suppressed low, and it is possible to avoid a situation in which the operation of each memory bare chip 1 becomes unstable due to the temperature rise, and in the worst case, a thermal runaway occurs. it can.

Next, a memory system 20 in which the memory module 10 is mounted on an SO-DIMM board 11 as a printed wiring board will be described. FIG. 7 is a diagram illustrating a memory system 20 on which the memory module 10 of the present embodiment is mounted. The SO-DIMM board 11 shown in FIG.
Is implemented, and 2 is provided for each memory module 10.
A capacitor 12 for preventing noise is provided for each unit. On one surface, a controller 13 for checking each memory bare chip 1 and the like is mounted. Each memory module 10 is mounted by the LCC method described above, and the capacitor 12 and the controller 13
It is mounted by MT (Surface Mount Technology) method.

The SO-DIMM board 11 shown in FIG. 7 has the same result as mounting 16 memories on one side and 16 memories on both sides. For example, each of the memory bare chips 1 constituting the memory module 10 is 4M × 4 bits of D
In the case of a RAM, the memory capacity of each memory module 10 is 8 Mbytes, and the memory capacity of the entire memory system 20 is 32 Mbytes.

FIG. 8 is a diagram showing a cross section of the memory system 20 of the present embodiment shown in FIG. As shown in FIG. 8, a plurality of grooves 14 are formed on the surface of the module substrate 2 opposite to the surface on which the memory bare chips 1 are mounted, and these grooves 14 are locally generated by the respective memory bare chips 1. A heat radiating member 15 for dispersing the generated heat to a wide area of the SO-DIMM substrate 11 is attached. Also,
The memory module 10 includes the heat radiating member 1 in these grooves 14.
5 is used as the mounting surface (contact surface).
It is in contact with the IMM substrate 11.

As described above, the memory system 20 of the present embodiment includes the SO-DIMM board 11 of the memory module 10.
A plurality of grooves 14 are formed on the mounting surface
The heat radiating member 15 is attached. When each memory bare chip 1 mounted on the memory module 10 generates heat, this heat is transmitted to the heat dissipating members 15 approaching each memory bare chip 1, so that almost the entire surface of the memory module 10 on which each heat dissipating member 15 is formed. , And the local temperature rise near each memory bare chip 1 can be reduced. Also, the SO-DI of the memory module 10
Since each heat radiating member 15 is formed over almost the entire surface of the mounting surface on the MM substrate 11, the heat radiating area is enlarged.
Heat is efficiently transmitted to the SO-DIMM substrate 11 with which each heat radiating member 15 is in direct contact, or each heat radiating member 15
Then, heat is efficiently radiated into the air around the memory system 20 through the module substrate 2 and the resin 6, and the memory bare chip 1 is cooled. For this reason, the temperature rise of each memory bare chip 1 can be suppressed low, and it is possible to avoid a situation in which the operation of each memory bare chip 1 becomes unstable due to the temperature rise, and in the worst case, a thermal runaway occurs. it can.

As shown in FIG. 9, a plurality of grooves 14 are formed on both contact surfaces of the module substrate 2 and the SO-DIMM substrate 11 so as to face each other. May be attached. In this case, since the grooves 14 are formed in both the module substrate 2 and the SO-DIMM substrate 11, the volume of the heat radiation member 15 attached to the grooves 14 can be increased, and the diffusion of heat generated from each memory bare chip 1 can be increased. Can be promoted. Therefore, the temperature rise of each memory bare chip 1 can be suppressed low, and the situation where the operation of each memory bare chip 1 becomes unstable due to the temperature rise can be avoided.

Further, as shown in FIG. 10, a plurality of grooves 14 are formed only on the contact surface of the SO-DIMM substrate 11 without forming the grooves 14 and attaching the heat radiation member 15 to the module substrate 2. A heat radiating member 15 may be attached to these grooves 14. In this case, since the formation of the groove 14 and the attachment of the heat radiation member 15 to the module substrate 2 are not performed, the manufacturing process of the memory module 10 can be simplified.

In the embodiment described above, the module substrate 2
Alternatively, the groove 1 is formed in at least one of the SO-DIMM substrates 11.
4 was formed, and a heat radiating member 15 was attached to the groove 14 to suppress the temperature rise of each memory bare chip 1.
Even when the memory module 10 or the memory system 20 is formed as a cavity without attaching the heat radiating member 15 to the memory chip, the temperature rise of each memory bare chip 1 can be suppressed low.

FIG. 11 is a view showing a cross-sectional shape of the memory module 10A when the heat radiation member 15 is not attached to the groove 14. The cross section shown in FIG.
This corresponds to the cross section taken along the line B '. As shown in FIG. 11, a plurality of grooves 14 are formed on a surface of the module substrate 2 opposite to the surface on which the memory bare chip 1 is mounted. Each groove 14 has a predetermined shape, for example, a substantially semicircular cross section, and is formed substantially parallel to the short side of the module substrate 2 from one long side of the module substrate 2 to the other long side opposite thereto. ing. By making the cross section semicircular, heat radiation from the surrounding module substrate 2 can be improved. The plurality of grooves 14 are formed in a range that does not contact the external connection terminals 8 attached to the module substrate 2. SO-DI memory module 10A
When mounting on the MM substrate 11 or the like, one surface of the module substrate 2 on which the groove 14 is formed is set as a mounting surface (contact surface).

As described above, the memory module 10A
By forming the plurality of grooves 14 on the mounting surface on the SO-DIMM substrate 11, the heat radiation area of the memory module 10 can be increased, and the air flowing through these grooves 14 can efficiently dissipate heat. it can. For this reason, the temperature rise of each memory bare chip 1 can be suppressed low.

FIG. 12 is a diagram showing a cross section of a memory system 20A in which the memory module 10A shown in FIG. As shown in FIG. 12, the memory system 20A includes a memory module 10A.
A plurality of grooves 14 are formed on the mounting surface of the SO-DIMM substrate 11 of FIG. Therefore, the memory module 10
When mounted on the O-DIMM board 11, these grooves 14
Forms a cavity.

As described above, in the memory system 20A, the surface on which the plurality of grooves 14 of the memory module 10A are formed is used as the mounting surface (contact surface) on the SO-DIMM substrate 11, so that the memory module 10A and the SO-DIMM DIMM
Since cavities are formed by the grooves 14 on the contact surface of the substrate 11, the heat radiation area of the memory system 20 can be increased, and heat can be efficiently radiated by the air flowing through the cavities. For this reason, the temperature rise of each memory bare chip 1 can be suppressed low, and the situation where the operation of each memory bare chip 1 becomes unstable due to the temperature rise can be avoided.

Further, when a plurality of grooves 14 are formed on both contact surfaces of the module substrate 2 and the SO-DIMM substrate 11 as shown in FIG.
Even when a plurality of grooves are formed only on the contact surface of the MM substrate 11, the heat radiation area of the memory system 20A can be increased by forming the plurality of grooves 14, and the air flowing through the cavity formed by these grooves 14 The heat can be efficiently dissipated. For this reason, the temperature rise of each memory bare chip 1 can be suppressed low, and the situation where the operation of each memory bare chip 1 becomes unstable due to the temperature rise can be avoided.

The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention. In the above-described embodiment, the groove 14 is formed substantially parallel to the short side of the memory module 10.
5 or the SO-
Even when the grooves 14 or the heat radiating members 15 are formed together with the grooves 14 in a lattice shape as in the DIMM board 11B, the diffusion of heat can be promoted and the heat radiating area can be increased. Can be.

The memory module 10 shown in FIG.
C and the SO-DIMM board 11C shown in FIG.
A similar effect can be obtained when the concave portion 16 or the heat radiating member 15 is formed together with the concave portion 16 over substantially the entire contact surface between the memory module 10C and the SO-DIMM substrate 11C.

Further, a conductive pattern having good thermal conductivity may be attached as the heat radiating member 15 without forming the groove 14 and the concave portion 16. SO-DIMM of the memory module 10
The conductive pattern as shown in FIGS. 5, 15 and 17 on the contact surface with the substrate 11 or the conductive pattern as shown in FIGS. 7, 16 and 18 on the contact surface with the memory module 10 of the SO-DIMM substrate 11 Is formed, the diffusion of heat can be promoted, and the heat radiation area can be increased.
Temperature rise can be kept low. In addition, by using a conductive pattern formed over a wide area as a ground region, noise resistance can be improved.

Further, in the above-described embodiment, an example has been described in which the memory bare chip is COB-mounted on the module substrate by wire bonding, but flip-chip mounting may be performed. In this case, higher-density mounting is possible, so that the outer dimensions of the memory module can be further reduced. FIG. 19 is a diagram showing a module substrate when the memory bare chip 1 is flip-chip mounted, and shows a module substrate when the memory bare chip 1 shown in FIG. 1 is flip-chip mounted. As shown in FIG. 19, pads 4 'are formed on the module substrate at regular intervals with the pads 3 of the memory bare chip 1 shown in FIG. 1, and these pads 4' and the pads 3 of the memory bare chip 1 face each other. With this arrangement, flip-chip mounting can be performed.

In the above-described embodiment, the pads 3 are formed in a row at the center of each memory bare chip 1, and these pads 3 and the pads 4 formed between the two memory bare chips 1 are bonded to the bonding wires. Although the connection is made by 5, the formation position of the pad 3 or the pad 4, the number of the bare chips 1 for memory, and the like are not limited to this. For example, a memory bare chip or a memory module as shown in FIGS. 20 to 28 may be used.

In the above embodiment, the module substrate 2
Although an example in which a DRAM is mounted on the memory device is described above, it is also possible to mount another type of memory bare chip 1 such as an SRAM or a flash ROM.

In the above-described embodiment, an example in which the memory module 10 is mounted on the SO-DIMM board 11 has been described.
The present invention is not limited to the MM substrate 11, and is not limited to
Other memory boards such as a Memory Module) board or a motherboard or a daughter board may be used.

FIG. 2 shows an example in which the sealing frame 7 is provided near the outer periphery of the module substrate 2 and the resin 6 is poured. However, the method of solidifying the chip mounting surface of the module substrate 2 with the resin 6 is described in FIG. For example, as shown in FIG. 29A, a method of forming a transfer mold by injection molding, or as shown in FIG. 29B, simply using a resin without using a sealing frame 7 or a mold. 6 into the chip mounting location.

[0040]

As described above, according to the present invention, at least one of the attachment of the heat radiating member and the formation of the concave portion is performed on the mounting surface of the memory module on the printed wiring board. The heat generated in the memory chip is diffused or the heat dissipation area is enlarged by the formed concave portion, and the heat generated from the memory chip is efficiently radiated to the outside. For this reason, it is possible to suppress a temperature rise that causes unstable operation of the memory chip. In a memory system in which a memory module is mounted on a printed wiring board, at least one of attachment of a heat radiating member and formation of a concave portion is provided on one or both of the contact surface on the memory module side and the contact surface on the printed wiring board side. Heat is diffused from the memory module to a wide area of the memory system by the heat radiating member, or the heat radiating area is enlarged by the formed concave portion, and the heat generated from the memory chip is efficiently radiated to the outside. For this reason, it is possible to suppress a temperature rise that causes unstable operation of the memory chip.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating a memory module according to an embodiment.

FIG. 2 is a sectional view taken along line AA ′ of FIG.

FIG. 3 is a perspective view showing a part of the memory module shown in FIG. 1;

FIG. 4 is a sectional view taken along line BB ′ of FIG. 1;

FIG. 5 is a diagram schematically showing a mounting surface of the memory module shown in FIG. 1 on a printed wiring board.

FIG. 6 is a view schematically showing a mounting surface of the memory module shown in FIG. 1 on a printed wiring board when a heat radiation member longer than a short side of the memory module is attached.

FIG. 7 shows a memory module shown in FIG.
It is a figure showing the state where it was mounted on the M board.

FIG. 8 is a diagram showing a cross section of the memory system in a case where a groove is formed or a heat radiation member is attached only to a memory module.

FIG. 9 is a diagram showing a cross section of the memory system when grooves are formed and heat radiating members are attached to both the memory module and the SO-DIMM substrate.

FIG. 10 is a diagram showing a cross section of the memory system in a case where a groove is formed or a heat radiation member is attached only to the SO-DIMM substrate.

FIG. 11 is a diagram showing a cross section of a memory module in which a heat dissipation member is not attached to a groove.

FIG. 12 is a diagram showing a cross section of a memory system in which a groove is formed only in a memory module.

FIG. 13 is a diagram showing a cross section of a memory system in which grooves are formed in both the memory module and the SO-DIMM substrate.

FIG. 14 is a diagram showing a cross section of a memory system in which a groove is formed only in an SO-DIMM substrate.

FIG. 15 is a view schematically showing a memory module in which a lattice-like groove is formed on almost the entire contact surface with the SO-DIMM substrate.

FIG. 16 is a diagram showing an SO-DIMM substrate in which a lattice-like groove is formed at a mounting position of a memory module.

FIG. 17 is a diagram schematically showing a memory module in which a concave portion is formed on almost the entire contact surface with the SO-DIMM substrate.

FIG. 18 is a diagram showing an SO-DIMM substrate in which a concave portion is formed on almost the entire contact surface with a memory module.

FIG. 19 is a diagram showing a pad configuration on a module substrate when a memory bare chip is flip-chip mounted.

FIG. 20 is a plan view of a memory module showing an example in which bonding wires are alternately drawn.

FIG. 21 is a plan view of a memory module formed by using a memory bare chip having pads arranged in two rows parallel to a long side.

FIG. 22 is a plan view of a memory module formed by using another memory bare chip having pads arranged in two rows parallel to a long side.

FIG. 23 is a plan view of a memory module including a memory bare chip having pads arranged in two rows in parallel with a short side.

FIG. 24 is a plan view of a memory module formed by using another memory bare chip having pads arranged in two rows in parallel with a short side.

FIG. 25 is a plan view of a memory module formed by using another memory bare chip having pads arranged in two rows in parallel with a short side.

FIG. 26 is a diagram illustrating an example in which a plurality of wires are alternately drawn out.

FIG. 27 is a diagram showing an example in which pads are formed in two rows on a module substrate.

FIG. 28 is a plan view of a memory module configured using two memory bare chips.

FIG. 29 is a view showing a modified example of a resin covering a memory bare chip on a memory module.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 bare chip for memory 2 module board 3, 4 pad 5 bonding wire 8 external connection terminal 10 memory module 11 SO-DIMM board 14 groove 15 heat dissipation member 16 recess 20 memory system

Claims (8)

[Claims] 1. A memory module comprising: a plurality of memory chips cut from a semiconductor wafer mounted on one surface of a module substrate; and a heat radiating member mounted on the other surface. 2. A memory module comprising: a plurality of memory chips cut from a semiconductor wafer mounted on one surface of a module substrate; and a recess formed on the other surface. 3. The memory module according to claim 2, wherein a heat radiation member is formed in the concave portion. 4. The memory module according to claim 1, wherein the heat radiation member is formed over substantially the entire surface of a module substrate including a region corresponding to the memory chip. 5. A memory module having a plurality of memory chips cut out of a semiconductor wafer mounted on one surface of a module substrate, and a printed wiring board on which the memory module is mounted, wherein the memory module and the printed wiring are provided. A memory system comprising a heat radiating member interposed between plates. 6. A memory module having a plurality of memory chips cut from a semiconductor wafer mounted on one surface of a module substrate, and a printed wiring board on which the memory module is mounted, wherein one surface of the memory module is provided. And a recess in at least one of the opposing regions of the printed wiring board. 7. The memory system according to claim 6, wherein a heat radiating member is formed in the concave portion. 8. The memory system according to claim 5, wherein the heat radiating member is formed over substantially the entire surface of the module substrate including a region corresponding to the memory chip.