JP2007317986A - Electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic apparatus, which is reduced in packaging volume and cost, and reduced in thermal resistance of a power supply component, thereby improving cooling efficiency. <P>SOLUTION: In a power supply of the electronic apparatus, there is provided a power supply board 27 including a semiconductor device 32 mounted thereon and used as a switch of a switching power supply via a connector 25 from a processor board 22 with a microprocessor 24 mounted thereon. There is further mounted a heat sink 31 common to the semiconductor device 32 and the microprocessor 24 mounted on the power supply board 27. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electronic device, and more particularly to a technique effective when applied to a power supply device of an electronic device and a cooling system thereof.

  Conventionally, a power supply device as shown in FIG. 1 is known as a power supply device used for an electronic device or the like. In the power supply device shown in FIG. 1, the switching unit 52 switches the DC power input from the DC input power source 60 to the input unit 51 including the input capacitor 61 based on the control signal output from the driving unit 70. Electric power is supplied to the load 66 from the output unit 53 including the commutation diode 63 and the output filter 55. The voltage or current output to the load 66 is detected by the detection unit 67, and the detected value and the control target value of the load 66 set by the setting unit 68 are compared by the comparison calculation unit 69. A control signal based on the comparison result is output to the switching unit 52. In this way, the power supplied to the load 66 such as a semiconductor integrated circuit is controlled to coincide with the control target value.

  A specific circuit configuration of such a power supply apparatus is shown in FIG. The switching unit 52 includes an active element 62 (for example, a transistor or a MOSFET). The output unit 53 includes a commutation diode 63 and an output filter 55 including a choke coil 64 and a capacitor 65. The control unit 54 includes a comparison calculation unit 69, a setting unit 68, and a drive unit 70. Further, the control unit 54 includes an oscillation circuit (not shown), and outputs a pulse signal from the driving unit 70 to the active element 62. As a result, the DC voltage Vin from the DC input power supply 60 applied to the active element 62 is switched.

  In the power supply device shown in FIG. 2, when the active element 62 is on, DC power is charged to the choke coil 64 and the capacitor 65 and supplied to the load 66. When the active element 62 is off, the energy charged in the choke coil 64 and the capacitor 65 is supplied to the load 66 through the commutation diode 63.

  At this time, the control unit 54 monitors the output voltage Vo detected by the detection unit 67 in the comparison calculation unit 69, compares this with the control target value set by the setting unit 68, and based on the comparison result from the drive unit 70. The control signal is output to the switching unit 52. As a result, the active element 62 is controlled to be turned on / off, and the electric power supplied to the load 66 is controlled to coincide with the control target value. The output voltage Vo at this time is expressed by the following equation (1).

Vo = Vin × (Ton / T) (1)
Here, Vin is an input DC voltage, T is a period of a pulse signal output from the drive unit 70, and Ton is a period of time during which the active element 62 is conductive in the period T. That is, Ton / T represents the duty ratio.

  Incidentally, a diode that is a passive element is usually used on the commutation side of the output unit 53 as shown in FIG. 2, but the commutation diode 63 has a current-voltage characteristic as shown in FIG. If the current exceeds a predetermined value, the forward voltage becomes saturated. This saturation voltage is about 0.9V to 1.3V for high-speed diodes and about 0.45V to 0.55V for Schottky diodes. Thus, there is a problem that power loss occurs due to saturation of the forward voltage of the commutation diode 63 and power conversion efficiency is deteriorated. Furthermore, since the power loss is large and the junction temperature of the element rises, the larger the output current is, the more commutation diodes 63 (two or three, etc.) are connected in parallel to distribute the power loss per element. There is a problem that it is necessary to suppress the junction temperature.

  In order to solve this problem, as shown in FIG. 4, a synchronous rectification type power supply device using a commutation MOSFET 3 on the commutation side is known. As shown in FIG. 5, the current-voltage characteristic of the diode is non-linear, whereas the current-voltage characteristic of the MOSFET is linear depending on the gate voltage, and the voltage drop is smaller than that of the diode. It uses small things.

  Next, a semiconductor integrated circuit (LSI: Large Scale Integrated Circuits) serving as a load of the power source will be described. There are a microprocessor, a graphic processor, a main memory, and the like that consume a large current in an LSI. In this specification, the microprocessor is mainly discussed. Specifically, Pentium (registered trademark) of Intel Corporation in the United States and Power PC of IBM Corporation in the United States are applicable.

  Microprocessors have increased current consumption year by year, ranging from tens to hundreds of amperes per processor. In order to cope with such a large current, the power source for processors is mainly configured by connecting the rectifying MOSFET 2 and the commutating MOSFET 3 shown in FIG. 4 as one unit and connecting them in parallel. FIG. 6 shows an example in which four power supplies are connected in parallel. The power supply unit 71 includes the rectifying MOSFET 2 and the commutation MOSFET 3 shown in FIG. In the figure, 72 is an inductor, 73 is an output capacitor, and 74 is a load.

  The following three keywords can be listed as recent microprocessor development trends.

(1) Increase in current consumption (2) Decrease in operating voltage (3) Adoption of multi-core Here, these keywords will be briefly described. Since the number of transistors mounted on the processor and the clock frequency increase year by year, the current consumption of the processor increases. In addition, the size of the transistor has been reduced year by year due to the miniaturization of the manufacturing process, and the operating voltage has been lowered accordingly.

  Multi-core is a single LSI chip equipped with multiple circuit blocks with processor functions, and because of its excellent performance per power, it can be used for electronic devices of 1 watt or less, such as mobile phones, and servers over 100 watts. It is being considered.

  Next, we will examine the effects of microprocessor development trends on power supply specifications. The number of power supplies is expected to increase due to “(1) Increase in current consumption” and “(3) Adoption of multi-core”. As the number of power supplies increases, the mounting area of the power supplies increases, and thus further miniaturization of the power supplies is required.

  When “(2) Decrease in operating voltage” proceeds, the power source must be placed near the processor as a load. This is because when the operating voltage is lowered, the allowable range of voltage fluctuation is reduced, and voltage drops due to parasitic resistance and parasitic inductance caused by the printed circuit board, socket, and package from the power source to the processor cannot be ignored.

  As described above, the requirements for the power source are “miniaturization” and “placement near the load”, and FIG. 7 (Non-patent Document 1) is an example of mounting that can realize these. The processor board 22 is attached from the mother board 20 via the connector 21, and the microprocessor 24 and the output capacitor 23 are attached to the processor board 22. The microprocessor 24 is connected to the thermal bonding material 29 (TIM: Thermal Interface). Material) and the heat spreader 30 are connected to the heat sink 31. On the other hand, the power supply component 26 is mounted on the back surface of the power supply board 27 via the connector 25, and a heat sink 28 for power supply is attached to the front surface side of the power supply board 27, that is, the back surface side of the power supply component.

FIG. 8 shows an example of a desktop personal computer motherboard that is currently mass-produced. Locations related to the microprocessor and the power source include a microprocessor socket 80, a capacitor 81 constituting an output filter of the power source, an inductor 82, and a power MOSFET 83 used as a switch of the switching power source. Compared to FIG. 8, the power supply component 26 is arranged near the microprocessor 24 in FIG. 7, so that the voltage drop from the power supply to the processor can be reduced. Further, since the heat sink is attached to the power supply board, the heat dissipation is improved and the power supply can be downsized.
Kaladhar Radhakrishnan et al, Optimization of Package Power Delivery and Power Removable Solutions to meet Platform Level Challenge, Intel Develooper. 2005 Special table 2003-528449 gazette JP 2004-342735 A

  However, this cooling system requires two heat sinks for the microprocessor and the power supply, increasing the mounting volume and cost. Further, since the heat sink of the power supply is attached to the back surface of the power supply component surface of the power supply board, there is a problem that the thermal resistance of the power supply component is large.

  Furthermore, if the thermal resistance of the power supply component is large, the switching frequency cannot be improved, and the output filter composed of the inductor and the capacitor becomes large. Further, since the power source is increased in size, it is difficult to dispose the power source near the processor, there is a problem that the voltage drop in the current path from the power source to the processor is large, and the performance of the processor deteriorates.

  Accordingly, the present invention has been made to solve the above problems, and provides an electronic device that aims to reduce the mounting volume and cost, reduce the thermal resistance of the power supply components, and improve the cooling efficiency. There is to do.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

  In order to achieve the above object, the present invention attaches a power supply board on which a semiconductor element used as a switch of a switching power supply is mounted via a connector from a processor board on which a processor is mounted, and a semiconductor mounted on the power supply board A common heat sink is attached to the element and the processor.

  Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

  According to the present invention, the electronic device has an effect that the cooling performance can be improved without increasing the mounting volume and cost. Furthermore, the improvement in cooling performance makes it possible to improve the switching frequency of the power supply, and the output filters such as capacitors and inductors can be downsized. Further, since the power source is downsized, the power source can be arranged near the processor, and the voltage drop from the power source to the processor can be reduced.

  In the following embodiments, when it is necessary for the sake of convenience, the description will be divided into a plurality of sections or embodiments. However, unless otherwise specified, they are not irrelevant to each other. The other part or all of the modifications, details, supplementary explanations, and the like are related. Further, in the following embodiments, when referring to the number of elements (including the number, numerical value, quantity, range, etc.), especially when clearly indicated and when clearly limited to a specific number in principle, etc. Except, it is not limited to the specific number, and may be more or less than the specific number. Further, in the following embodiments, the constituent elements (including element steps and the like) are not necessarily indispensable unless otherwise specified and apparently essential in principle. Needless to say. Similarly, in the following embodiments, when referring to the shapes, positional relationships, etc. of the components, etc., the shapes are substantially the same unless otherwise specified, or otherwise apparent in principle. And the like are included. The same applies to the above numerical values and ranges.

  In all the drawings for explaining the embodiments, parts having the same function are given the same reference numerals, and repeated explanation thereof is omitted as much as possible. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 9 shows a cross-sectional view of the power supply device according to the first embodiment of the present invention.

  The power supply device of the present embodiment is housed in a housing of an electronic device (shown in FIG. 17 described later). This electronic device is equipped with a microprocessor (first semiconductor element) 24 that requires cooling in order to ensure normal operation, and a power supply device is provided for supplying power to the microprocessor 24. Yes.

  As shown in FIG. 4 described above, the power supply apparatus according to the present embodiment includes a DC input power supply 1, a rectifying MOFET 2, a commutation MOSFET 3, an inductor 4, an output capacitor 5, a load 6, an input capacitor 7, a control circuit 9, and the like. In particular, as shown in FIG. 9, a processor board (first semiconductor element) 32 including a semiconductor element (second semiconductor element) 32 of a rectifying MOSFET 2 and a commutation MOSFET 3 used as switches of a switching power supply and having a microprocessor 24 mounted thereon. A power supply board (second electrical wiring board) 27 on which a semiconductor element 32 is mounted is connected to one microprocessor board 24 through an electrical connector (connecting portion) 25, and the microprocessor 24 semiconductor element 32 is shared. A heat sink (thermal diffusion element) 31 is provided.

  In the present embodiment, a processor board 22 is attached from the mother board 20 via a connector 21, and a microprocessor 24 and a capacitor 23 constituting an output filter are mounted on the processor board 22. The power supply board 27 is attached to the processor board 22 via a connector 25, and the power supply board 27 is provided with a semiconductor element 32 and an inductor 33 constituting an output filter. The heat spreader 30 is connected to the microprocessor 24 via a thermal bonding material 29 (TIM: Thermal Interface Material). Here, the heat sink 31 is disposed so as to contact the heat spreader 30 and the semiconductor element 32.

  FIG. 10 shows a plan view of the power supply board 27 of FIG. A central portion of the power supply substrate 27 is opened to secure a space for the heat spreader 30, a semiconductor element 32 is arranged around the opening, an inductor 33 around the opening, and a driving IC (Inregulated Circuits) for driving the semiconductor element 32. ) 34 is arranged. A dotted line 35 indicates the outer periphery of the heat sink 31 of FIG.

  Thus, according to the present embodiment, the power supply board 27 is attached from the processor board 22 through the connector 25, and the heat sink 31 common to the semiconductor element 32 and the microprocessor 24 mounted on the power supply board 27 is attached. The following effects can be obtained.

  Since there is only one heat sink 31, the mounting volume and cost can be reduced. Further, since the heat sink 31 is mounted on the surface of the semiconductor element 32, the thermal resistance is small, the switching frequency of the power supply device can be improved, and the output filter such as the inductor 4 and the output capacitor 5 can be downsized. Also. By downsizing the power supply device, the power supply device can be arranged near the microprocessor 24, the voltage drop in the current path from the power supply device to the microprocessor 24 can be reduced, and the performance of the microprocessor 24 is improved.

(Embodiment 2)
Next, an embodiment using a multi-chip module (MCM: Multi Chip Module) or SiP (System in Package) will be described. The multichip module includes a semiconductor element used as a switch in a switching power supply and a driving IC that drives the semiconductor element. Such a multi-chip module is described in Japanese Patent Publication No. 2003-528449 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2004-342735 (Patent Document 2).

  FIG. 11 is a diagram illustrating the function of the multichip module in the second embodiment of the present invention. The multichip module 16 includes a rectifying MOSFET 2 and a commutation MOSFET 3 that are used as switches of a switching power supply, and a drive unit (third semiconductor element) 15 that drives the rectifying MOSFET 2 and the commutation MOSFET 3. Others are the same as in the first embodiment.

  FIG. 12 is a plan view of the power supply board 27 according to the second embodiment of the present invention, and the multi-chip module 36 and the inductor 33 constituting the output filter are arranged around the opening.

  As described above, according to the present embodiment, the rectification MOSFET 2, the commutation MOSFET 3, and the drive unit 15 are configured by the multichip module 36, so that the size can be further reduced in addition to the same effects as those of the first embodiment. realizable.

(Embodiment 3)
Next, Embodiment 3 of the present invention will be described with reference to FIG. The present embodiment is different from the first embodiment shown in FIG. 9 in that an insulating material 41 made of an insulating material having a good thermal conductivity is interposed between the semiconductor element 32 and the heat sink 31. There are two reasons for using the insulating material 41. One is to adjust the height of the heat spreader 30 and the semiconductor element 32 when the common heat sink 31 is attached, and the insulating material 41 serves as a buffer material for height adjustment. The second reason is that when a plurality of semiconductor elements 32 are normally mounted on the power supply substrate 27 and the electrodes of the semiconductor elements 32 are exposed on the heat sink 31 side, the potentials of the respective electrodes are different, so it is necessary to take insulation. Because there is.

  Thus, according to the present embodiment, since the insulating material 41 is interposed between the semiconductor element 32 and the heat sink 31, in addition to the same effects as in the first embodiment, the heat sink 31 can be easily attached. The insulating property of the semiconductor device 32 can be improved.

(Embodiment 4)
Next, Embodiment 4 of the present invention will be described with reference to FIG. The present embodiment is different from the first embodiment in that a heat pipe 37 is used instead of the heat sink. The heat pipe 37 is a cooling system with a phase change from liquid to gas, and a refrigerant is sealed in the heat pipe 37. The refrigerant that has been heated near the microprocessor 24 and turned into a gas moves through the heat pipe 37, reaches the low temperature portion, and becomes a liquid. This liquid moves to the high-temperature microprocessor 24 by the capillary effect and gravity, and is heated again to become a gas. The cooling by the heat pipe 37 improves the cooling performance as compared with forced air cooling, so it is used for a server where the processor generates a large amount of heat or a notebook computer where a large heat sink is not attached near the processor due to space constraints.

  In FIG. 14, the heat pipe 37 is covered with cases 38 and 39 in order to improve reliability from a mechanical and chemical viewpoint.

  FIG. 15 is a plan view of FIG. 14, in which a plurality of heat pipes 37 are arranged in parallel.

  FIG. 16 is a view of the heat pipe 37 as viewed from the longitudinal direction. The refrigerant in the heat pipe 37 is heated in the vicinity of the microprocessor 24 to become a gas, and then moves through the heat pipe 37 to heat the metal or the like. The material is cooled by the material 40 having good conductivity and the heat sink 31 to become a liquid, and is moved to the vicinity of the microprocessor 24 by gravity and capillary action, and thereafter, the microprocessor 24 and the semiconductor element 32 are cooled by repeating this.

  Thus, according to the present embodiment, the same effect as in the first embodiment can be obtained by using the heat pipe 37 instead of the heat sink.

(Embodiment 5)
Finally, an embodiment of an electronic device will be described. The electronic device is mounted with the power supply device according to any of the first to fourth embodiments.

  FIG. 17 is a diagram illustrating an electronic device according to Embodiment 5 of the present invention. As shown in FIG. 17, the main body of a desktop personal computer as an example of an electronic device includes a casing 100 formed of a metal plate in a cubic shape, and a power switch is provided on the front panel 101. Various types of switches, connection terminals, indicator lamps and the like are provided. In addition, a driver device 102 that drives various external information storage media such as a floppy (registered trademark) disk, a CD, and a DVD is provided inside the housing 100, and an insertion / removal port for various media serves as a front panel unit 101. It arrange | positions so that it may open to. Reference numeral 103 in the drawing denotes a storage unit provided in the housing 100, for example, a hard disk device. Reference numeral 104 denotes a lid that covers the casing 100.

  On the other hand, on the back side of the housing 100, an electronic circuit unit 105 including the above-described power supply device is disposed. Reference numeral 106 in the figure denotes a power supply unit for supplying desired power from a commercial power supply to each unit including the driver device 102, the storage unit 103, and the electronic circuit unit 105.

  As described above, according to the present embodiment, the power supply device is provided in the housing 100 of the electronic device, and the same effect as in the first to fourth embodiments can be obtained as the electronic device.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

  The present invention relates to an electronic device, and is particularly effective when applied to a power supply device for an electronic device and a cooling system thereof.

It is a block diagram explaining the function of the conventional power supply device. It is a block diagram explaining the function and electric circuit of the conventional power supply device. It is a figure which shows the voltage drop of a diode, and the relationship of an electric current. It is a figure explaining the electric circuit of the conventional power supply device. It is a figure which shows the voltage drop of a diode and MOSFET, and the relationship of an electric current. It is a block diagram explaining the parallel operation | movement of a power supply in the conventional power supply device. It is sectional drawing which shows the conventional power supply device. It is a bird's-eye view which shows the components arrangement | positioning of the present motherboard. It is sectional drawing which shows the power supply device of Embodiment 1 of this invention. In the power supply device of Embodiment 1 of this invention, it is a top view which shows a power supply board | substrate. In the power supply device of Embodiment 2 of this invention, it is a figure explaining the electric circuit of the multichip module for power supplies. In the power supply device of Embodiment 2 of this invention, it is a top view which shows a power supply board | substrate. It is sectional drawing which shows the power supply device of Embodiment 3 of this invention. It is sectional drawing which shows the power supply device of Embodiment 4 of this invention. It is a top view which shows the power supply device of Embodiment 4 of this invention. It is sectional drawing which shows the power supply device (figure seen from another direction with respect to FIG. 14) of Embodiment 4 of this invention. It is a figure explaining the electronic device of Embodiment 5 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... DC input power source, 2 ... Rectification MOSFET, 3 ... Commutation MOSFET, 4 ... Inductor, 5 ... Output capacitor, 6 ... Load, 7 ... Input capacitor, 9 ... Control circuit, 14 ... Control part, 15 ... Drive part 16 ... multi-chip module, 20 ... motherboard, 21,25 ... connector, 22 ... processor board, 23 ... output capacitor, 24 ... microprocessor, 26 ... power supply component, 27 ... power supply board, 28, 31 ... heat sink, 29 ... Thermal bonding material, 30 ... heat spreader, 32 ... semiconductor element, 33 ... inductor, 34 ... driving IC, 35 ... outer periphery of heat sink, 36 ... multichip module, 37 ... heat pipe, 38, 39 ... case, 40 ... heat conduction Material, 41 ... insulating material with good thermal conductivity, 51 ... input unit, 52 ... switching unit, 53 ... output , 54 ... control unit, 55 ... output filter, 60 ... DC input power supply, 61 ... input capacitor, 62 ... active element, 63 ... commutation diode, 64 ... choke coil, 65 ... capacitor, 66 ... load, 67 ... detection part , 68 ... setting section, 69 ... comparison operation section, 70 ... drive section, 71 ... power supply unit, 72 ... inductor, 73 ... output capacitor, 74 ... load, 80 ... socket for microprocessor, 81 ... capacitor, 82 ... inductor, DESCRIPTION OF SYMBOLS 83 ... Power MOSFET, 100 ... Housing | casing, 101 ... Front panel part, 102 ... Driver apparatus, 103 ... Memory | storage part, 104 ... Cover, 105 ... Electronic circuit part, 106 ... Power supply part.

Claims (5)

An electronic device in which a first semiconductor element that requires cooling in order to ensure normal operation is mounted in the housing,
A power supply device for supplying power to the first semiconductor element in the housing;
The power supply device includes a second semiconductor element used as a switch of a switching power supply, and the second semiconductor is connected to a first electrical wiring board on which the first semiconductor element is mounted via an electrical connection portion. An electronic apparatus, wherein a second electrical wiring board on which an element is mounted is connected, and the first semiconductor element and the second semiconductor element include a common thermal diffusion element. An electronic device in which a first semiconductor element that requires cooling in order to ensure normal operation is mounted in the housing,
A power supply device for supplying power to the first semiconductor element in the housing;
The power supply apparatus includes a semiconductor module in which a second semiconductor element used as a switch of a switching power supply and a third semiconductor element that drives the second semiconductor element are mounted in one module, and the first semiconductor element The first electrical wiring board on which the semiconductor module is mounted is connected to the second electrical wiring board on which the semiconductor module is mounted via an electrical connection portion, and the first semiconductor element and the semiconductor module share a common thermal diffusion. An electronic device comprising an element. An electronic device in which a first semiconductor element that requires cooling in order to ensure normal operation is mounted in the housing,
A power supply device for supplying power to the first semiconductor element in the housing;
The power supply device includes a second semiconductor element used as a switch of a switching power supply, and the second semiconductor is connected to a first electrical wiring board on which the first semiconductor element is mounted via an electrical connection portion. A second electrical wiring board on which an element is mounted is connected, the first semiconductor element and the second semiconductor element include a common thermal diffusion element, and the second semiconductor element and the thermal diffusion element are electrically An electronic device characterized by being connected via an insulating material. An electronic device in which a first semiconductor element that requires cooling in order to ensure normal operation is mounted in the housing,
A power supply device for supplying power to the first semiconductor element in the housing;
The power supply apparatus includes a semiconductor module in which a second semiconductor element used as a switch of a switching power supply and a third semiconductor element that drives the second semiconductor element are mounted in one module, and the first semiconductor element The first electrical wiring board on which the semiconductor module is mounted is connected to the second electrical wiring board on which the semiconductor module is mounted, and the first semiconductor element and the semiconductor module have a common heat. An electronic apparatus comprising a diffusion element, wherein the semiconductor module and the heat diffusion element are connected via an electrical insulating material. In the electronic device of any one of Claims 1-4,
The electronic device is characterized in that the heat diffusing element comprises a heat sink, a heat pipe, or a combination thereof.

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