JP2006202975A - Electronic device with cooling structure for high-density mounting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide cooling structure suitable for three-dimensional structure for high-density mounting in a simplified composition. <P>SOLUTION: An electronic device 1 of high-density mounting is provided with two or more double-sided mounting circuit board units accumulated by stack structure to the height direction of a mounted semiconductor device 11; a connector 4 which makes electric connection between the double-sided mounting circuit board units at the end of the double-sided mounting circuit board unit, arranged so that at least one side of the two or more of the accumulated double-sided mounting circuit board units may make an opening; and cooling structure established between the semiconductor devices which are disposed opposite to each other by the stack structure, and come into contact with each of the semiconductor devices disposed opposite to each other. At least one of the double-sided mounting circuit board units has a ground layer formed on the substrate surface. The cooling structure has a heat sink 5 extended between the semiconductor devices disposed opposite to each other, and the heat sink coming into contact with semiconductor devices mounted on the same surface as the ground layer has a projection coming into contact with the ground layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cooling structure for a high-density mounting electronic device in which semiconductor elements are electrically connected with high density by a double-sided mounting circuit board unit.

  As network devices increase in speed and capacity, it is required to reduce the wiring distance between semiconductor elements and increase the mounting density. On the other hand, in semiconductor elements that are increasingly miniaturized, the amount of heat generated increases, so a cooling structure has become essential.

  2. Description of the Related Art Conventionally, as a high-density mounting cooling structure in an electronic device, a structure in which heat sinks formed on a semiconductor element surface are installed face to face and cooled by an air flow flowing between the heat sinks is known (for example, see Patent Document 1). ). This method is employed when the semiconductor chip on the circuit board is a low power chip. By transferring the heat removed from the chip to the heat sink side into a convection air flow, heat generated by the operation of the chip can be removed.

  For medium-power chips, a cooling structure using a heat pipe containing a liquid as a refrigerant has been proposed (see, for example, Patent Document 2). However, since the cooling structure becomes large, it is not suitable for a three-dimensional mounting type electronic device that mounts a plurality of semiconductor elements at high density. In particular, in a structure in which heat pipes and single-side mounted electronic circuit modules are alternately stacked, the entire electronic device becomes large.

On the other hand, as a form for mounting semiconductor elements at high density, a method of realizing a stacked structure of semiconductor elements by folding a flexible printed wiring board on which semiconductor elements are mounted has been proposed (for example, see Patent Document 3). This method is intended to flexibly mount an element with a small amount of heat at a high density, but does not consider any heat dissipation.
JP-A-6-291228 JP-A-6-21290 JP 2000-307055 A

  The configuration disclosed in Patent Document 1 is a cooling structure for efficiently cooling a plurality of substrates on which one or more semiconductor elements are mounted on the same plane. Triangular radiating fins for cooling are formed on each element surface, and an air flow is made to flow through the space between the radiating fins facing each other to remove heat. In this configuration, a space for installing the radiation fins on the surface of the element and a space for passing the duct between the opposing radiation fins are required.

  For this reason, there is a limit to increasing the density, and the wiring distance between a plurality of semiconductor elements stacked in a three-dimensional stack structure cannot be shortened.

  Therefore, an object of the present invention is to provide a high-density mounting cooling structure for efficiently radiating heat while maintaining high-density mounting of semiconductor elements.

  It is another object of the present invention to provide a high-density mounting cooling structure with a simple configuration that can be easily incorporated into an electronic device in which a plurality of semiconductor elements are three-dimensionally mounted with high density.

  In order to solve the above problems, the present invention realizes a cooling structure that can be incorporated into an electronic device in which circuit boards mounted on both sides are stacked with a single insertion.

  In order to realize this, a connector is provided on the circuit board so that at least one side is opened when the circuit boards on which the semiconductor elements are mounted on both sides are three-dimensionally stacked. From this opening side, a heat sink is inserted at a time so as to be in contact with both of the semiconductor element surfaces facing each other, and the heat generated in the semiconductor elements is led out of the three-dimensionally stacked circuit boards.

In a first aspect of the present invention, an electronic device having a cooling structure is provided. Electronic devices
(A) a plurality of double-sided mounting circuit board units stacked in a stack structure in the height direction of the mounted semiconductor element;
(B) An electrical connection between the double-sided mounted circuit board units is arranged such that at least one side of the stacked double-sided mounted circuit board units is opened, and at an end of the double-sided mounted circuit board unit. A connector for performing
(C) a cooling structure provided between the semiconductor elements facing each other in the stack structure and in contact with each of the facing semiconductor elements.

  Thereby, it is possible to eliminate the extra space between the semiconductor chips facing each other between the double-sided mounting circuit board units stacked in the stack structure, and to guide the heat generated in the chips to the outside of the stack structure.

  In a favorable configuration example, the cooling structure has a heat sink extending between semiconductor elements facing each other, at least one of the stacked double-sided mounted circuit board units has a ground layer formed on the substrate surface, The heat sink that contacts the semiconductor element mounted on the same surface as the ground layer has a protrusion that contacts the ground layer.

  Thereby, a heat sink can be functioned as a ground and the wiring distance between double-sided mounting circuit board units can be shortened substantially.

  In another preferable configuration example, the connector includes a plurality of pins. In this case, each double-sided mounting circuit board unit has a plurality of through holes formed at positions corresponding to the pins, and the through holes are selectively subjected to conductive processing in each double-sided mounting circuit board unit.

  With this configuration, it is possible to perform wiring connection between arbitrary layers of the multi-stage double-sided mounting circuit board unit, and the degree of freedom in designing the electronic device is improved.

According to a second aspect of the present invention, there is provided a heat sink assembly used in an electronic device having a high-density mounting circuit board having a three-dimensional stack structure. The heat sink assembly
An S-shaped or reverse S-shaped first heat dissipating plate having a first fin portion;
An L-shaped second heat sink having a second fin portion;
Are integrally joined so that the first fin portion and the second fin portion extend in parallel,
The first fin portion and the second fin portion are mounted on the double-sided mounting circuit board unit that is three-dimensionally stacked and inserted between the semiconductor elements facing each other. And a projecting portion provided so as to be in contact with the ground layer formed.

  Accordingly, it is possible to realize a cooling mechanism that can be assembled between opposing semiconductor elements of a plurality of double-sided mounting circuit board units with a simple configuration with a single insertion.

  The cooling structure can be easily incorporated into the high-density stack structure of the double-sided mounting substrate.

  As a result, it is possible to achieve both high density and cooling efficiency.

  The manufacturing cost of a high-density electronic device having a cooling function can be reduced.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings.

  FIG. 1 is a configuration example of a double-sided mounted circuit board unit 10 used in an electronic device according to an embodiment of the present invention. Semiconductor elements (chips) 11 such as LSI are mounted on both surfaces of the circuit board 12. In the example of FIG. 1, the semiconductor element 11 is mounted in a vertically symmetrical position, but it is not always necessary to have a symmetrical arrangement. Further, the internal wiring structure of each semiconductor element 11 is not necessarily symmetrical.

  Such double-sided mounting circuit board units 10 are stacked in the height direction to constitute a high-density three-dimensional mounting electronic device.

  FIG. 2 is a side view of the electronic apparatus 1 using the double-sided mounted circuit board unit 10 shown in FIG. Terminals for electrical connection (not shown) are provided at both ends of the double-sided mounting circuit board unit 10, and electrical connection between the double-sided mounting circuit board units 10 is performed by the connector 4. The connector 4 is electrically connected to the mother board 6 and establishes an electric connection between the semiconductor element 11 and other electronic components (not shown) mounted on the mother board.

  In the stack structure of FIG. 2, the semiconductor elements 11 mounted on both surfaces of the circuit board 12 are arranged to face each other. A heat radiating plate 5 is inserted in a space generated between the semiconductor elements 11 facing each other. In the side view of FIG. 2, each of the plurality of heat sinks 5 is inserted into the space between the opposing semiconductor elements 11. However, as will be described later, the plurality of heat sinks 5 are integrated to dissipate heat. It constitutes a plate assembly.

  The material of the heat radiating plate 5 is preferably a material having high thermal conductivity, low cost and easy machining. As an example, aluminum or an aluminum alloy is used.

  In the present embodiment, the thickness of the heat sink 5 is set to be less than 1 mm from the viewpoint of downsizing the entire electronic device 1. In order to fill a gap between the surface of the heat sink 5 and the surface of the semiconductor element 11, heat release grease may be applied on the element 11 or the surface of the heat sink 5 in advance.

  FIG. 3 is a top view of the electronic device 1 of FIG. As described above, electrical connection terminals (not shown) are provided at the upper and lower ends of the double-sided mounting circuit board unit 10, and the double-sided mounting circuit board units 10 stacked by the connector 4 are electrically connected to each other. ing.

  The heat sink 5 is inserted in the left-right direction of FIG. 3 and penetrates the space between the semiconductor elements 11 (see FIG. 2) facing each other. In the example of FIG. 3, the length L1 in the left-right direction of the heat sink 5 is longer than the corresponding side length L2 of the double-sided mounted circuit board unit 10. With this configuration, the heat sink 5 can be easily inserted into the space between the semiconductor elements 11 facing each other.

  In order to allow the heat sink 5 to be inserted in the direction of the arrow (left and right), the connector 4 on the mother board 6 is arranged so as to be connected to two sides along the insertion direction of the double-sided mounting circuit board unit 10. ing. That is, the connector 4 is arranged so that at least one side of the stacked double-sided circuit board unit 10 is opened so that the heat sink 5 can be inserted.

  In the example of FIG. 3, the connector 4 is arranged along two opposite sides of the double-sided mounting circuit board unit 10, but it may be arranged so as to surround the three sides, or between the double-sided mounting circuit board units 10. The connector 4 may be disposed only on one side of the double-sided mounted circuit board unit as long as electrical connection can be ensured.

  FIG. 4 is a perspective view showing how the heat sink assembly 15 is assembled to the stacked double-sided mounting circuit board unit 10.

  The heat radiating plate assembly 15 is configured by combining a first heat radiating plate 5a bent in an S shape (or an inverted S shape) and a second heat radiating plate 5b bent in an L shape. When aluminum or aluminum alloy is used for the heat sinks 5a and 5b, the processing is easy, and the heat sinks 15a and 5b, which are separately processed, are laminated and integrated to create the heat sink assembly 15 at a low cost. can do.

  In this case, the L-shaped heat radiating plate 5b and the fin portions 5f of the L-shaped heat radiating plate 5b and the fin portions 5f of the L-shaped heat radiating plate 5b are formed by sequentially superposing the L-shaped heat radiating plates 5b on the basis of the S-shaped heat radiating plate 5a. They are assembled so as to extend in parallel with each other at a predetermined interval.

  In the example of FIG. 4, the heat sink assembly 15 is inserted in the direction of the arrow, and the parallel fin portions 5 f are inserted into the space between the opposing elements 11 of the stacked double-sided mounting circuit board unit 10. As described above, heat radiation grease may be applied to the surface of the semiconductor element 11 mounted on both surfaces of the circuit board 12 prior to insertion. Although not depicted in FIG. 4, it is assumed that the plurality of stacked double-sided circuit board units 10 are electrically connected to the connectors on the front side and / or the back side of the paper.

  FIG. 5 shows a state where the heat sink assembly 15 is completely inserted between the semiconductor elements 11 facing each other. In this state, even if heat is generated due to high-speed operation of each semiconductor element 11 (see FIG. 4), heat is removed by the heat radiating plates 5a and 5b.

  Although not shown, a heat radiating fin may be separately provided on the base portion 15 a of the heat radiating plate assembly 15. Alternatively, a cooling mechanism such as a chiller may be connected to the tail portion 15 b of the heat sink assembly 15 on the mother board 6. In this case, the degree of cooling can be easily controlled from the outside of the electronic device 1 in which the double-sided mounting circuit board units 10 are three-dimensionally stacked, and the degree of freedom of adjustment is increased.

  FIG. 6 is a diagram showing a modification of the cooling structure of the electronic device shown in FIG. In the example of FIG. 6, the ground layer 22 is formed on the surface of the substrate 12 of the double-sided mounted circuit board unit 10, and the heat sink 5 is brought into contact with the ground layer 22 with the protrusions 5. When a conductive material such as aluminum is used for the heat sink 5, the heat sink 5 and the ground layer 22 of the double-sided mounting circuit board unit 10 are electrically connected to each other so that the heat sink 5 Also functions as a ground, and the actual wiring distance can be shortened. In addition, inductance generated between the semiconductor element 11 and the ground layer 22 can be reduced.

  The protrusion 5d of the heat sink 5 can be easily formed, for example, by press working. Also in this case, the S-shaped (or inverted S-shaped) heat sink 5a in which the protrusions 5d are formed in advance by press working and the L-shaped heat sink 5b in which the protrusions 5d are formed in advance are bonded to each other. And the heat sink assembly 15 can be produced easily. The heat sink assembly 15 provided with the protrusions 5d can also be inserted into the gap between the stacked double-sided mounted circuit board units 10 from the side where the connector is not installed (opening side).

  FIG. 7 is a view showing an example of a connector structure according to the embodiment of the present invention. A plurality of connector pins 24 are provided along two opposing sides on the mother board 6.

  Through holes 17 for electrical connection and alignment are formed on two opposite sides of the circuit board 12 of the double-sided mounting circuit board unit 10. A spacer 25 is disposed between the adjacent double-sided mounting circuit board units 10, and a through-hole 25 h is provided in the spacer at a position corresponding to the through-hole 17 of the double-sided mounting circuit board unit 10. The spacer is an insulator such as rubber, for example, and the distance between the double-sided mounted circuit board units 10 can be adjusted by adjusting the thickness thereof. By inserting the conductive connector pin 24 into the through hole 17 of the double-sided mounting circuit board unit 10 and the through hole 25h of the spacer 25, the double-sided mounting circuit board unit 10 is positioned.

  The heat sink assembly 15 shown in FIG. 4 or 6 is inserted between the double-sided mounting circuit board unit 10 positioned by the connector pin 24 and the spacer 25 from the opening side where the connector pin 24 is not disposed.

  FIG. 8 is a diagram illustrating an electrical connection method of the connector pins 24. The inner wall of the through hole 17 formed in the circuit board 12 of the double-sided mounting circuit board unit 10 is selectively subjected to conductive treatment. That is, each double-sided mounting circuit board unit 10 has a through hole 17a that has been subjected to a conductive process and a through hole 17b that has not been subjected to a conductive process depending on the position of the wiring 19 formed on the circuit board 12. The through hole 17 a subjected to the conductive treatment has a metal layer 17 m made of, for example, plating on its inner wall, and establishes an electrical connection between the double-sided mounted circuit board unit 10 by the wiring 19 and the connector pin 24. The through hole 17b not subjected to the conductive treatment is used exclusively for alignment.

  In this way, by selectively conducting the through holes 17 formed in the double-sided mounting circuit board unit 10, conduction between desired layers (circuit boards) of the three-dimensional stack structure can be realized. Thereby, the freedom degree of design improves.

Finally, the following notes are disclosed regarding the above description.
(Appendix 1) A plurality of double-sided mounting circuit board units stacked in a stack structure in the height direction of the mounted semiconductor element;
A connector that is arranged so that at least one side of the plurality of stacked double-sided mounting circuit board units is opened, and that electrically connects the double-sided mounting circuit board units at an end of the double-sided mounting circuit board unit When,
An electronic device comprising: a cooling structure provided between the semiconductor elements facing each other in the stack structure and in contact with each of the facing semiconductor elements.
(Appendix 2) At least one of the double-sided mounted circuit board units has a ground layer formed on the substrate surface,
The cooling structure has a heat sink extending between the semiconductor elements facing each other,
2. The electronic device according to appendix 1, wherein a heat radiating plate in contact with a semiconductor element mounted on the same surface as the ground layer has a protruding portion in contact with the ground layer.
(Supplementary Note 3) The cooling structure includes a heat sink assembly in which a plurality of heat sinks extending in parallel with each other are integrally combined, and the heat sink assembly is integrally incorporated between the semiconductor elements from the opening. The electronic device as set forth in Appendix 1, wherein
(Appendix 4) The heat sink assembly is
An S-shaped or reverse S-shaped first heat dissipating plate having a first fin portion;
An L-shaped second heat sink having a second fin portion;
The electronic device according to appendix 3, wherein the first fin portion and the second fin portion are integrally joined so as to extend in parallel.
(Additional remark 5) The said double-sided mounting circuit board unit has a ground layer formed on the substrate surface,
The electronic device according to appendix 4, wherein the first fin portion and the second fin portion have a protrusion that contacts a ground layer on the double-sided mounted circuit board unit.
(Appendix 6) The connector is composed of a plurality of pins,
Each of the double-sided mounting circuit board units has a plurality of through holes formed at positions corresponding to the pins, and in each of the double-sided mounting circuit board units, the through holes are selectively conductively processed. The electronic device according to Supplementary Note 1, wherein the electronic device is characterized.
(Supplementary note 7) The electronic device according to any one of supplementary notes 1 to 6, further comprising a chiller connected to the heat radiating plate outside the stack structure.
(Supplementary Note 8) An S-shaped or reverse S-shaped first heat radiating plate having a first fin portion;
An L-shaped second heat sink having a second fin portion;
Are integrally joined so that the first fin portion and the second fin portion extend in parallel,
The first fin portion and the second fin portion are mounted on the double-sided mounting circuit board unit that is three-dimensionally stacked and inserted between the semiconductor elements facing each other. A heat sink assembly comprising a protrusion provided to be in contact with a ground layer formed on the heat sink.

It is a figure which shows the structural example of the double-sided mounting circuit board unit used with the electronic device which concerns on one Embodiment of this invention, and is stacked | stacked three-dimensionally. It is a side view of an electronic device having a cooling structure according to an embodiment of the present invention. FIG. 3 is a top view of the electronic device of FIG. 2. FIG. 3 is a perspective view of a heat dissipation assembly incorporated as a cooling structure in the electronic device of FIG. 2. It is a perspective view which shows the state by which each heat sink of the heat radiating assembly was inserted between the semiconductor elements which a double-sided mounting circuit board unit opposes. It is a figure which shows the modification of a cooling structure. It is the schematic which shows an example of the connector used with the electronic device of FIG. It is a figure which shows the example of a connection between the double-sided mounting circuit board units by a connector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electronic device 4 Connector 5 Heat sink 5a S-shaped (reverse S-shaped) heat sink 5b L-shaped heat sink 5d Projection part 5f Fin part 6 Mother board 10 Double-sided mounting circuit board unit 11 Semiconductor element (chip)
12 Circuit board 15 Heat sink assembly 17 Through hole 22 Ground layer 24 Connector pin 25 Spacer

Claims (5)

A plurality of double-sided mounting circuit board units stacked in a stack structure in the height direction of the mounted semiconductor elements;
A connector that is arranged so that at least one side of the plurality of stacked double-sided mounting circuit board units is opened, and that electrically connects the double-sided mounting circuit board units at an end of the double-sided mounting circuit board unit When,
An electronic device comprising: a cooling structure provided between the semiconductor elements facing each other in the stack structure and in contact with each of the facing semiconductor elements. At least one of the double-sided mounted circuit board units has a ground layer formed on the substrate surface,
The cooling structure includes a heat sink extending between the semiconductor elements facing each other,
2. The electronic device according to claim 1, wherein a heat dissipation plate in contact with a semiconductor element mounted on the same surface as the ground layer has a protruding portion in contact with the ground layer. The cooling structure includes a heat sink assembly in which a plurality of heat sinks extending in parallel with each other are integrally combined,
The electronic device according to claim 1, wherein the heat sink assembly is integrally incorporated between the semiconductor elements from the opening. The connector is composed of a plurality of pins,
Each of the double-sided mounting circuit board units has a plurality of through holes formed at positions corresponding to the pins, and in each of the double-sided mounting circuit board units, the through holes are selectively conductively processed. The electronic device according to claim 1, characterized in that: An S-shaped or reverse S-shaped first heat dissipating plate having a first fin portion;
An L-shaped second heat sink having a second fin portion;
Are integrally joined so that the first fin portion and the second fin portion extend in parallel,
The first fin portion and the second fin portion are mounted on the double-sided mounting circuit board unit that is three-dimensionally stacked and inserted between the semiconductor elements facing each other. A heat sink assembly comprising a protrusion provided to be in contact with a ground layer formed on the heat sink.

Images