JP3016460B2 - Electronic device mounting structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting structure of an electronic device for transferring a signal between switches used in a multiprocessor system or a communication path device at a high speed and mounting them at high density. .

[0002]

2. Description of the Related Art FIG. 6 is a cross-sectional view showing a mounting structure of a multiprocessor or a communication path device using a conventional pin grid type case. Here, 1 is an LSI chip, and 2 is the L chip.
A wire bonding portion for connecting the SI chip to the multi-chip module substrate; a multi-chip module substrate for performing signal wiring between the LSI chips or to another multi-chip module; Mounting case for storing
I / O pins for signal connection and power supply to a printed wiring board 9 described later, and 6 for the multi-chip module substrate 3
Wire bonding part for connecting the mounting case 4 to the
Is a cap for protecting the LSI chip 1 on the multi-chip module substrate 3, and 8 is the LSI chip 1
An air-cooled heat sink for radiating heat from the IC; 9, a printed wiring board for mounting a large number of multi-chip modules; 10, internal wiring for signals formed in the printed wiring board 9; Reference numeral 12 denotes a development wiring formed in the mounting case 4 in the flow direction of the high-speed signal between the chip modules.

FIG. 7 is a top view showing a mounting structure of a multiprocessor or a communication channel device using a conventional pin grid type case. Here, the inner layer wiring 10 formed on the printed wiring board 9 cannot be actually seen from the surface, but is shown for ease of explanation. Reference numeral 13 denotes a horizontal signal transmission direction, and reference numeral 14 denotes a vertical signal transmission direction.

The configurations shown in FIGS. 6 and 7 assume a case where a large number of processors are two-dimensionally mesh-wired, or a case where communication communication channels are connected in a matrix.

In this case, when the number of signal connections between the multi-chip modules increases, the number of I / O pins 5 increases. However, if a PGA (Pin Grid Array) type case as shown in FIG. There is a limitation on the pitch of the pins that can be inserted into the printed wiring board 9, and since the pin pitch is large, a sufficient area is required to secure the required number of I / O connections. In this case, there is a problem that the size of the multi-chip module increases because the development wiring 12 is required. In other words, the wiring length on the multi-chip module increases, and as a result, the signal propagation delay time increases, or the load capacity of the wiring increases, so that the drive capability of the LSI chip 1 needs to be increased. (Increase in power consumption).

FIG. 8 is a diagram showing a developed wiring image of a portion connected to a conventional pin grid type case I / O pin. FIG. 8 shows a developed wiring 12 portion in the mounting case 4 shown in FIG. It is the figure seen in the depth direction of the paper surface. Where 1
5 is a via in the mounting case 4 of the multi-chip module connected to the I / O pin 5, 16 is a developed wiring in the mounting case 4, and 17 is a wire bonding for connection with the multi-chip module substrate 3. Pads 18 represent cavities for mounting the multichip module.

As is apparent from FIG. 8, each I / O pin 5
Since the expansion wiring 16 is required, the size of the multi-chip module increases. Further, in order to connect the signal from the wire bonding pad 17 for connection with the multi-chip module substrate 3 to the via 15 in the mounting case 4 connected to the I / O pin 5, a detouring wiring 16 is required. In this case, there is a problem that a cross-talk between signals increases because a region where the pitch between the development wirings 16 becomes narrow is generated.

Further, since the PGA type I / O pin 5 is used, the inductance of the portion is increased, and the length of the development wiring 16 is also increased, which causes an increase in the inductance and the capacitance in the portion. As a result, the delay increases, and there is also a problem that high-speed signal transmission is limited by reflection or the like. In addition, since the I / O pins 5 are used, the inductance of the power supply system is large. As a result, power supply noise increases, which limits the speed of high-speed signal transmission and limits the number of signals that can be operated simultaneously. There were also problems such as giving.

FIG. 9 is a sectional view of a wiring structure in the conventional printed wiring board 9, in which 19 is a signal wiring, 20 is a ground / power supply layer, and 21 is an insulating layer. Printed wiring board 9
When the PGA type connection is made, the wiring in the printed wiring board 9 needs a multilayer wiring as shown in FIG. 9, and there is a problem that the manufacturing cost is increased.

[0010]

As described above, the case where the conventional PGA type case is adopted is required for the necessary I / O.
Attempting to secure the number of connections increases the size of the device, increases the wiring length on the multi-chip module substrate, increases the signal propagation delay time, and increases the drive capability of the LSI chip. Was.

An object of the present invention is to enable high-speed signal transfer in an electronic device such as a switch unit used in a multiprocessor system or a communication path device, and to reduce the size of the device by mounting them at high density. It is to provide a mounting structure that can be used.

[0012]

According to the electronic device mounting structure of the present invention, a plurality of fine signal connection pads are provided on the periphery of a multi-chip module substrate, while a plurality of fine signal connection pads are provided on the surface of the printed wiring board and the multi-chip module. A fine signal connection pad is provided at a position opposite to the fine signal connection pad provided on the chip module substrate surface, and the signal connection pad provided on the periphery of the multi-chip module substrate and the fine signal connection pad are provided on the printed wiring board surface. Between the signal connection pads, a conductive elastomer having a fine pitch is inserted, and the multi-chip module substrate is housed or fixed in a mounting case made of a member having excellent thermal conductivity, and In the area where the multi-chip module substrate is mounted,
A press plate is provided on the surface of the printed wiring board on which the multi-chip module board is not mounted, and a screw is fixed between the mounting case and the press plate, and the multi-chip is formed by the conductive elastomer. A signal connection pad provided on a peripheral portion of a module substrate is electrically connected to a signal connection pad on a surface of the printed wiring board, and a signal wiring connection between the multi-chip module substrates is formed on the surface of the printed wiring board. This uses a microstrip line formed in a layer.

[0013]

According to the present invention, a conductive pattern having a fine pitch is provided between a signal connection fine pad provided on the surface of a multi-chip module substrate and a signal connection pad provided opposite to a printed wiring board. It is electrically connected by the elastomer.

[0014]

FIG. 1 is a view showing one embodiment of the present invention, and is a cross-sectional view showing a mounting structure of a multiprocessor or a communication path device. Here, 1, 2, and 8 are the same L as described above.
31 shows an SI chip, a wire bonding part, and an air-cooled heat sink, 31 is a multi-chip module substrate, 32
Is a mounting case formed of a photothermal conductive member for mounting a multi-chip module, 33 is a cap, 34 is a conductive elastomer, 35 is a printed wiring board surface wiring (microstrip line configuration), 36 is a printed wiring board, 37A , 37B are signal flow directions, 38 is a fixing screw, and 39 is a holding plate having spring properties.

FIG. 2 is a top view showing a mounting structure of a multiprocessor or a communication path device. Reference numeral 40 denotes a hole for the fixing screw 38.

FIG. 3 is a front view of the multi-chip module according to the present invention.
Reference numeral 42 denotes a signal connection pad for connection with 6, and a sealing ring.

FIG. 4 is a pair of FIG.
Image of wiring pattern on printed wiring board 36, FIG.
3A and 3B are cross-sectional views of the wiring structure of the printed wiring board 36 according to the present invention. Here, 43 is a printed wiring board surface wiring A, 44 is a printed wiring board surface wiring B, 45
Is a mounting position of the conductive elastomer 34, 46 is a mounting position of the multi-chip module substrate 31, 47 is a signal connection pad on the printed wiring board 36, 48 is a surface wiring A, 49 is a surface wiring B, 50 is Control signals and the like are shown.

As is apparent from FIGS. 1 to 5, fine signal connection pads 41 can be provided on the multi-chip module substrate 31, so that development wiring can be shortened.
As a result, the size of the multi-chip module substrate 31 can be reduced (see FIG. 3).

Since the wiring on the printed wiring board 36 also has a microstrip line configuration, the wiring may be formed on the printed wiring board 36, and there is no need to provide through holes. Pad 4
7 can be formed, and the multi-chip module substrates 31 can be connected with a fine wiring pitch. For this reason, the signal wiring length between the multi-chip module substrates 31 can be reduced, and the connection line length can be significantly reduced in combination with the above-described wiring length reduction effect in the multi-chip module substrate 31, so that the delay time can be reduced ( (See FIG. 4). Further, since the capacitance of the wiring can be reduced, the switching delay due to the load can be reduced, and the driving capability of the I / O driver circuit built in the LSI chip 1 can be reduced.
Low power consumption of the entire device can also be achieved. Further, since the signal wiring is formed only on the surface of the printed wiring board 36, there is no need to use a multilayer printed wiring board, and the manufacturing cost can be greatly reduced. The conductive elastomer 34 is of a form in which fine conductive wires are implanted in the thickness direction of the insulating rubber plate so as not to contact each other. 47 conducts. For details, see the document "JAFulton et.al," Use of anisotropically condu
ctive polymers in ele-ctronic applications, ", Proc.
of 3rd International SAMPE Electronic Confe-rence,
Los Angeles, CA. pp. 578, 1989 ".

The connection pitch of the conductive elastomer 34 is as follows:
The size of the multi-chip module substrate 31 has been increased because the signal lines have been developed to the pitch of the pins because the size can be reduced by about one digit as compared with a normal pin type connector or the like. In the configuration, the development wiring is not required on the multi-chip module substrate 31, so that the multi-chip module substrate 31 can be reduced in size and the signal wiring length can be reduced, so that the propagation delay time can be greatly reduced.

Further, in order to form a microstrip line on the printed wiring board 36 for signal connection, a through hole having a large diameter (one digit or more larger than the via diameter of the multi-chip module) is provided in the printed wiring board 36. Since there is no need, the pitch of the signal connection pads 41 and 47 can be reduced. Therefore, when the conductive elastomer 34 is used, the fact that the connection can be made at a fine pitch can be fully utilized. As a result, the wiring length on the printed wiring board 36 can be reduced, and the propagation delay time can be significantly reduced.

Further, as shown in FIG.
8 and the ground wiring B49, the amount of crosstalk between the signal lines (between the surface wiring A48) can be suppressed, so that the number of simultaneously operating signal lines viewed from the crosstalk also increases. It becomes possible.

[0023]

As described above, according to the present invention, a multi-chip module substrate on which one or more LSI chips 1 are mounted is mounted on a plurality of printed wiring boards, and signal wiring between the multi-chip module substrates is reduced. In an electronic device that is connected only to an adjacent multi-chip module in a mesh shape, a plurality of fine signal connection pads are provided around a multi-chip module substrate, and on the other hand, on the surface of the printed wiring board and the multi-chip module substrate A fine signal connection pad is provided at a position facing the fine signal connection pad provided on the surface, and the signal connection pad provided on the periphery of the multi-chip module substrate and the signal connection pad on the printed wiring board surface are provided. A conductive elastomer having a fine pitch is inserted between the pad and the pad, and the multi-chip module base is inserted. Is housed or fixed in a mounting case made of a member having excellent thermal conductivity, and further in an area where the multi-chip module substrate is mounted, and on a surface of the printed wiring board on which the multi-chip module substrate is not mounted. Is provided with a holding plate, fixed between the mounting case and the holding plate with a fixing screw, a signal connection pad provided around the multi-chip module substrate by the conductive elastomer and a surface of the printed wiring board. The electrical connection between the upper signal connection pads and the signal wiring connection between the multi-chip module boards were made using the microstrip lines formed on the printed wiring board surface layer. Does not require deployment wiring, so the size of the multi-chip module can be reduced, Because it can shorten the line length, there is an advantage of greatly reducing the propagation delay time.

Further, since a microstrip line is formed on the printed wiring board for signal connection, it is not necessary to provide a through hole, so that the pitch of signal connection pads can be made finer. There is an advantage that the above wiring length can be reduced, and the propagation delay time can be greatly reduced.

Further, since the wiring length on the multi-chip module substrate and the printed wiring board can be reduced, the load capacity of the mounting system can be reduced.
The driving capability of the / O driver unit can be reduced, and there is an advantage that the power consumption of the entire device can be reduced.

Further, since the connection between the multi-chip module substrate and the printed wiring board uses a conductive elastomer, the length of the connection portion can be shortened. As a result, the inductance of the connection portion can be reduced, and the amount of power noise generated can be reduced. This has the advantage that the number of signal lines that can be operated simultaneously can be increased.

Further, since the printed wiring board has a microstrip line configuration, it is not necessary to use a multilayer substrate, and therefore, there is an advantage that the manufacturing cost can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a mounting structure of a multiprocessor or a communication path device according to the present invention.

FIG. 2 is a top view showing a mounting structure of a multiprocessor or a communication path device.

FIG. 3 is a front view of a multi-chip module according to the present invention.

FIG. 4 is an image diagram of a wiring pattern on a printed wiring board according to the present invention.

FIG. 5 is a sectional view of a wiring structure of a printed wiring board according to the present invention. FIG. 3 is a top view showing the mounting structure of FIG.

FIG. 6 is a cross-sectional view showing a mounting structure of a multiprocessor or a communication path device using a conventional pin grid type case.

FIG. 7 is a top view showing a mounting structure of a multiprocessor or a communication path device using a conventional pin grid type case.

FIG. 8 is a diagram showing a developed wiring image of a portion connected to a conventional pin grid type case I / O pin.

FIG. 9 is a sectional view of a wiring structure in a conventional printed wiring board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 LSI chip 2 Wire bonding part 8 Air-cooled heat sink 31 Multi-chip module board 32 Mounting case 33 Cap 34 Conductive elastomer 35 Printed wiring board surface wiring 36 Printed wiring board 37A Signal flow 37B Signal flow 38 Fixing screw 39 Holding plate 40 Fixation Screw hole 41 Signal connection pad 42 Sealing ring 43 Printed wiring board surface wiring A 44 Printed wiring board surface wiring B 45 Conductive elastomer mounting position 46 Multichip module mounting position 47 Signal connection pad 48 Surface wiring A 49 Surface wiring B 50 control signal

Claims (1)

(57) [Claims] 1. A multi-chip module board on which at least one LSI chip is mounted is mounted on a plurality of printed wiring boards, and signal wiring between the multi-chip module boards is meshed only with adjacent multi-chip modules. In the electronic device to be connected, a plurality of fine signal connection pads are provided on the periphery of the multi-chip module substrate, while fine signal connections are provided on the surface of the printed wiring board and on the surface of the multi-chip module substrate. A fine signal connection pad is provided at a position opposed to the signal pad, and a fine pitch is provided between the signal connection pad provided on the periphery of the multi-chip module substrate and the signal connection pad on the surface of the printed wiring board. A multi-chip module substrate having a conductive elastomer having excellent thermal conductivity. A holding plate is provided in a region where the multi-chip module substrate is mounted or fixed in the mounting case formed of, and on a surface of the printed wiring board on which the multi-chip module substrate is not mounted, and The case and the holding plate are fixed with screws, and between the signal connection pad provided on the periphery of the multi-chip module substrate by the conductive elastomer and the signal connection pad on the surface of the printed wiring board. Wherein the microstrip lines formed on the surface layer of the printed wiring board are used for signal wiring connection between the multi-chip module substrates.