JP6565576B2 - Power supply board - Google Patents

Description

  The present invention relates to a power supply board.

In power supply in an information processing apparatus such as a server apparatus, a primary power supply (AC power supply) supplied from a commercial power supply is converted into a secondary power supply (low-voltage DC power supply) by a power supply unit in the apparatus, and a motherboard provided in the apparatus Electric power is supplied to various parts of the substrate. After the voltage value of the power supplied to each part of the substrate is further converted into a voltage value corresponding to each component by the DC / DC converter, the power is supplied to each component. In power supply to a processor such as a CPU (Central Processing Unit), the voltage value of power supplied to various parts of the board is converted into a voltage value corresponding to the processor by a DC / DC converter, and then the power is supplied to the processor. The

For example, as shown in FIG. 9, CPU 111, DIMM (Dual
Inline Memory Module) 112, DC / DC converter 113, and high-speed transmission component 114
Is implemented. As shown in FIG. 10, power is supplied from the DC / DC converter 113 to the CPU 111 through a plurality of power supply paths 121 formed in the substrate 101. Also, as shown in FIG. 10, a plurality of signal transmission paths 122 are formed in the substrate 101. FIG. 9 is a plan view of the substrate 101, and FIG. 10 is a partial cross-sectional view of the substrate 101.

  The DC / DC converter 113 outputs a voltage that compensates for a voltage drop that occurs in the middle of the power supply path 121 in order to supply power to the CPU 111 with a predetermined voltage. Therefore, the DC / DC converter 113 is installed in the vicinity of the CPU 111 so that the voltage drop is reduced. As the transmission distance between the CPU 111 and the memory such as the DIMM 112 is shorter, the signal transmission in the server device is faster and the performance of the server device is improved. For example, as shown in FIG. 9, by arranging the DIMM 112 and the high-speed transmission component 114 in the vicinity of the CPU 111, the transmission distance between the CPU 111 and the DIMM 112 is shortened, and between the CPU 111 and the high-speed transmission component 114. The transmission distance is shortened.

International Publication No. 2004/004000 International Publication No. 2007/129526 Special table 2003-518759 gazette

  In recent years, the demand for high-performance server devices has increased, and there has been a demand for improved processor performance, faster signal transmission, and increased memory capacity. Increasing the processor frequency improves the performance of the processor. For example, when the frequency of the CPU 111 is increased, the power consumption of the CPU 111 is increased, so that a large current is supplied to the CPU 111 by increasing the number of DC / DC converters 113. When there is no empty area in the substrate 101 to which the DC / DC converter 113 can be added, for example, as shown in FIG. 11, the number of the DC / DC converters 113 is increased by increasing the outer shape of the substrate 101. Become. When the outer shape of the substrate 101 becomes large and the manufacturing size of the substrate 101 is out of the standard, the substrate 101 becomes difficult to manufacture or the manufacturing cost of the substrate 101 increases.

When the number of DC / DC converters 113 increases, the DC / DC converter 113 changes the CPU.
A power supply path 121 to 111 is added. As shown in FIG. 10, since a plurality of signal transmission paths 122 are formed in the substrate 101, an additional power feeding path 121 is formed in the substrate 101 so as to avoid the signal transmission path 122. In this case, an additional power supply path 121 is secured in the substrate 101 by increasing the inner layer of the substrate 101. When the inner layer of the substrate 101 increases and the manufacturing thickness of the substrate 101 becomes out of specification, it becomes difficult to manufacture the substrate 101 or the manufacturing cost of the substrate 101 increases.

  As shown in FIGS. 12A and 12B, when a power supply path 121 from the DC / DC converter 113 to the CPU 111 is added, the power supply path 121 is designed to avoid the signal transmission path 122 between the CPU 111 and the DIMM 112. FIG. 12A is a plan view of the substrate 101 before the feeding path 121 is added. FIG. 12B is a plan view of the substrate 101 after the power supply path 121 is added. In this case, since the additional power feeding path 121 is formed in the substrate 101 so as to avoid the signal transmission path 122, the power feeding path 121 becomes thin and long, and the influence of the voltage drop becomes large. Further, when the power feeding path 121 approaches the signal transmission path 122, power supply noise interferes with the signal transmission path 122, and transmission performance is degraded.

  The purpose of this case is to reduce voltage drop and power supply noise.

  A power supply board according to an aspect of the present invention includes a top surface on which a processor can be mounted, a bottom surface opposite to the top surface, and a plurality of first through holes that penetrate the bottom surface from the top surface and can be electrically connected to the processor. And a first substrate having a plurality of second through holes, a second substrate having a power supply device disposed at a position away from the lower surface of the first substrate, and mounted on the lower surface of the first substrate, A first conductor that electrically connects the first through hole and the power supply device, and is mounted on the lower surface of the first substrate, and electrically connects the plurality of second through holes and the power supply device. And a second conductor.

  According to this case, voltage drop and power supply noise can be reduced.

FIG. 1 is a schematic diagram of a power supply board. FIG. 2 is an external view of the pillar. FIG. 3 is a schematic diagram of a power supply board. FIG. 4 is a block diagram showing a power supply system of the power supply board. FIG. 5 is a diagram showing a wiring pattern in the inner layer of the power supply board. FIG. 6 is a diagram illustrating an interface between the main board and the CPU. FIG. 7 is an explanatory diagram of a method of connecting the main board and the power supply board. FIG. 8 is an explanatory diagram of a method for connecting the main board and the power supply board. FIG. 9 is a plan view of the substrate. FIG. 10 is a partial cross-sectional view of the substrate. FIG. 11 is a plan view of the substrate. FIG. 12A is a plan view of the substrate before the feeding path is added. FIG. 12B is a plan view of the substrate after the feeding path is added. FIG. 13 is a schematic diagram of a power supply board. FIG. 14 is a schematic diagram of the power supply board before the pillar is mounted on the power board. FIG. 15 is a schematic diagram of the power supply board when the pillar is mounted on the power board. FIG. 16 is a schematic diagram of the power supply board when the main board expands and the power supply board expands. FIG. 17 is a schematic diagram of the power supply board when the contraction speed of the power supply board is faster than the contraction speed of the main board. FIG. 18 is a schematic diagram of a power supply board. FIG. 19 is a schematic diagram of the power supply board when the outer diameter of the pillar is reduced. FIG. 20 is a schematic diagram of a power supply board. FIG. 21 is an external view of the pillar. FIG. 22 is an external view of the pillar.

  Hereinafter, a power supply substrate (electronic device) according to an embodiment will be described with reference to the drawings. The configuration of the power supply board shown below is an example, and the configuration of the power supply board according to the embodiment is not limited to the configuration shown below.

<Example 1>
The power supply board 1 according to the first embodiment will be described. FIG. 1 is a schematic diagram of a power supply substrate 1. The power supply board 1 includes a main board (motherboard) 2, a power board 3, and a plurality of pillars 4 disposed between the main board 2 and the power board 3. The main board 2 is formed of, for example, a plurality of resin layers. The main board 2 has an upper surface (first surface) on which the CPU 5 can be mounted and a lower surface (second surface) opposite to the upper surface. A CPU 5 can be mounted on the upper surface of the main board 2. The CPU 5 is mounted on the upper surface of the main board 2 via a plurality of solder balls 11 provided on the upper surface of the main board 2. Solder balls 11 are joined to electrodes (not shown) formed on the circuit surface of the CPU 5. The main board 2 is an example of a first substrate. The power supply substrate 3 is an example of a second substrate. The CPU 5 is an example of a processor.

  The main board 2 has a plurality of through holes 21 and a plurality of signal transmission paths 22 formed therein. Some of the plurality of solder balls 11 are arranged on a plurality of surface patterns 23 formed on the upper surface of the main board 2. In this case, a plurality of solder balls 11 are arranged on one surface pattern 23. The surface pattern 23 has conductivity and is formed using, for example, copper foil. The arrangement of the plurality of through holes 21 and the arrangement of the surface pattern 23 correspond to each other, and the plurality of through holes 21 and the surface pattern 23 are electrically connected.

  The through hole 21 has a hole penetrating the main board 2 and copper plating formed on a side wall of the hole penetrating the main board 2. The through hole 21 is also called a through via. For example, holes are formed in the main board 2 by drilling, laser, dry etching, or the like, and copper plating is formed on the sidewalls of the holes in the main board 2 by, for example, electroless plating or electroplating. The signal transmission path 22 includes wiring extending in the planar direction of the main board 2 and vias extending in the thickness direction of the main board 2. The signal transmission path 22 is a signal line used for transmitting a signal processed by the CPU 5.

  The CPU 5 can be electrically connected to the through hole 21 via the solder ball 11 and the surface pattern 23. The CPU 5 can be electrically connected to the signal transmission path 22 via the solder ball 11 and an electrode (not shown) formed on the upper surface of the main board 2.

A plurality of pillars 4 are mounted on the lower surface opposite to the upper surface of the main board 2 by surface mounting technology (SMT). A plurality of pillars 4 are arranged on a plurality of surface patterns 24 formed on the lower surface of the main board 2, and the pillars 4 are soldered to the lower surface of the main board 2 by soldering the pillars 4 and the surface pattern 24 with solder 25. Implemented. In this case, one pillar 4 is arranged on one surface pattern 24. The surface pattern 24 has conductivity and is formed using, for example, a copper foil.

  The through hole 21 and the surface pattern 24 are electrically connected, and the surface pattern 24 and the pillar 4 are electrically connected. The pillar 4 is connected to the power supply substrate 3. The pillar 4 has conductivity and is formed using, for example, copper. The pillar 4 is an example of a conductor. FIG. 2 is an external view of the pillar 4 and shows a side surface and a bottom surface of the pillar 4. The pillar 4 has a first portion and a second portion that is narrower than the first portion.

  The power supply board 3 is disposed at a position away from the lower surface of the main board 2 and has a plurality of DC / DC converters 6. The power supply substrate 3 is formed by a plurality of resin layers, for example. The plurality of DC / DC converters 6 are mounted on the lower surface of the power supply substrate 3. The DC / DC converter 6 is an example of a power supply device. The plurality of DC / DC converters 6 may be mounted on the upper surface opposite to the lower surface of the power supply substrate 3. The CPU 5 and the DC / DC converter 6 are electrically connected, and power (power supply) is supplied from the DC / DC converter 6 to the CPU 5 through the plurality of pillars 4 and the plurality of through holes 21. For example, the DC / DC converter 6 reduces the voltage supplied from the external power supply to the voltage for the CPU 5 and supplies power to the CPU 5.

  As shown in FIGS. 9 and 10, when the CPU 111 and the DC / DC converter 113 are arranged on the same plane of the substrate 101, the CPU 111 is connected to the CPU 111 from the DC / DC converter 113 in the substrate 101 so as to avoid the signal transmission path 122. Is formed. Therefore, the power supply path 121 from the DC / DC converter 113 to the CPU 111 becomes long.

  In the power supply board 1, a plurality of pillars 4 are arranged on the lower surface of the main board 2. That is, a power supply path from the DC / DC converter 6 to the CPU 5 is formed in the vertical direction of the main board 2. Therefore, the power supply path from the DC / DC converter 6 to the CPU 5 is shortened compared to the case where the power supply path is formed in the planar direction of the main board 2. The power supply board 1 has a shorter power supply path from the DC / DC converter 6 to the CPU 5 than the structure shown in FIGS. Therefore, according to the power supply substrate 1, it is possible to suppress a voltage drop in the power supply path from the DC / DC converter 6 to the CPU 5.

  According to the power supply board 1, a plurality of pillars 4 are arranged on the lower surface of the main board 2, whereby a power feeding path between the main board 2 and the DC / DC converter 6 can be arranged outside the main board 2. it can. That is, a part of the power supply path from the DC / DC converter 6 to the CPU 5 can be arranged outside the main board 2. Thereby, the power supply noise from the electric power feeding path | route with respect to the signal transmission path 22 of the main board 2 can be reduced.

  FIG. 3 is a schematic diagram of the power supply board 1 and shows a detailed configuration of the power supply board 3. The power supply substrate 3 has a plurality of through holes 31, 32, 33, 34 formed therein, a plurality of power supply wirings 35, and a plurality of ground wirings 36. In FIG. 3, one of the plurality of pillars 4 is indicated as a pillar 4A, and one of the plurality of pillars 4 is indicated as a pillar 4B. The pillar 4A is an example of a first conductor. The pillar 4B is an example of a second conductor. In FIG. 3, the through hole 21 electrically connected to the pillar 4A is indicated as a through hole 21A, and the through hole 21 electrically connected to the pillar 4B is indicated as a through hole 21B. The through hole 21A is an example of a first through hole. The through hole 21B is an example of a second through hole.

The through holes 31, 32, 33, 34 have a hole penetrating the power supply substrate 3 and a copper plating formed on a sidewall of the hole penetrating the power supply substrate 3. For example, holes are formed in the power supply substrate 3 by drilling, laser, dry etching, or the like, and copper plating is formed on the sidewalls of the holes by, for example, electroless plating or electroplating.

  The pillars 4A and 4B are mounted on the power supply substrate 3 by flow soldering (DIP). The second part of the pillar 4A is inserted into the hole of the through hole 31, and the second part of the pillar 4B is inserted into the hole of the through hole 32. The bottom surface of the power supply board 3 is immersed in molten solder, the pillars 4A and the through holes 31 are soldered with the solder 37, and the pillars 4B and the through holes 32 are soldered with the solder 37, whereby the pillars 4A and 4B are powered. Mounted on the substrate 3. The solder 37 flows into the gap between the pillar 4A and the through hole 31, and the pillar 4A and the through hole 31 are joined. The solder 37 flows into the gap between the pillar 4B and the through hole 32, and the pillar 4B and the through hole 32 are joined.

  The DC / DC converter 6 is electrically connected to the through holes 33 and 34. The through hole 33 is electrically connected to the power supply wiring 35, and the through hole 34 is electrically connected to the ground wiring 36. The power supply wiring 35 is electrically connected to the through hole 31. The ground wiring 36 is electrically connected to the through hole 32. The through hole 31 is electrically connected to the pillar 4A. The through hole 32 is electrically connected to the pillar 4B. From the DC / DC converter 6 to the CPU 5 by the solder ball 11, the surface pattern 23, the through hole 21A, 21B surface pattern 24, the pillars 4A, 4B, the through holes 31, 32, 33, 34, the power supply wiring 35 and the ground wiring 36. A power feeding path is formed. The power supply path from the DC / DC converter 6 to the CPU 5 includes a power supply path between the CPU 5 and the DC / DC converter 6 and a ground path between the CPU 5 and the DC / DC converter 6.

  As shown in FIG. 3, the pillar 4A is disposed immediately below the plurality of through holes 21A, and the pillar 4B is disposed directly below the plurality of through holes 21B. Therefore, the power feeding path between the main board 2 and the DC / DC converter 6 can be arranged immediately below the through holes 21A and 21B. Thereby, the power supply noise from the electric power feeding path | route with respect to the signal transmission path 22 of the main board 2 can be reduced.

  FIG. 4 is a block diagram showing a power supply system of the power supply board 1. As shown in FIG. 4, the pillars 4 </ b> A and 4 </ b> B are disposed in the central portion of the power supply substrate 3, and the DC / DC converter 6 is disposed in the outer peripheral portion outside the central portion of the power supply substrate 3. One pillar 4A and one pillar 4B are used as a set, the pillar 4A is used for power connection, and the pillar 4B is used for ground connection. That is, the pillar 4A is used as a part of the power supply path between the CPU 5 and the DC / DC converter 6, and the pillar 4B is used as a part of the ground path between the CPU 5 and the DC / DC converter 6. The pillar 4A may be used for ground connection and the pillar 4B may be used for power connection, without being limited to the example shown in FIG.

  The pillars 4A and 4B and the DC / DC converter 6 surrounded by the dotted line 41 belong to the first power supply system. The pillars 4A and 4B and the DC / DC converter 6 surrounded by the dotted line 42 belong to the second power supply system. The pillars 4A and 4B and the DC / DC converter 6 surrounded by the dotted line 43 belong to the third power supply system. The pillars 4A and 4B and the DC / DC converter 6 surrounded by the dotted line 44 belong to the fourth power supply system. The pillars 4A and 4B and the DC / DC converter 6 surrounded by the dotted line 45 belong to the fifth power supply system. Each of the DC / DC converters 6 belonging to the first to fifth power supply systems may supply power to the CPU 5 with different voltage values. Further, each of the DC / DC converters 6 belonging to the first to fifth power supply systems may supply power to the CPU 5 with the same voltage value.

FIG. 4 shows an example in which there are five power supply systems, but the number of power supply systems is not limited to the example in FIG. 4, and the number of power supply systems is changed according to the specifications of the CPU 5. Also good. A plurality of DC / DC converters 6 may belong to one power supply system. For example, in the example of FIG. 3, a plurality of DC / DC converters 6 belong to one power supply system, one pillar 4A and a plurality of DC / DC converters 6 are electrically connected, and one pillar 4B A plurality of DC / DC converters 6 are electrically connected.

  FIG. 5 is a diagram showing a wiring pattern in the inner layer of the power supply substrate 3. The wiring pattern includes a pattern of the power supply wiring 35 and a pattern of the ground wiring 36. As shown in FIG. 5, the inner layer of the power supply substrate 3 is partitioned (defined) into regions 51 to 55, and wiring patterns belonging to the first to fifth power supply systems are arranged in the regions 51 to 55, respectively. Yes. The arrangement of the areas 51 to 55 corresponds to the arrangement of the DC / DC converter converters 6 belonging to the first to fifth power supply systems. That is, the wiring patterns belonging to the first to fifth power supply systems are arranged immediately below the DC / DC converters 6 belonging to the first to fifth power supply systems. Since only the power supply components (DC / DC converter 6 and related components) are mounted on the power supply board 3, the mounting of the power supply parts and the wiring pattern in the inner layer of the power supply board 3 can be efficiently designed.

  One pillar 4A and one DC / DC converter 6 may be electrically connected. Accordingly, the power supply voltage may be supplied from one DC / DC converter 6 to the CPU 5 through one pillar 4A and a plurality of through holes 21A. Also, one pillar 4A and a plurality of DC / DC converters 6 may be electrically connected. Therefore, the power supply voltage may be supplied from the plurality of DC / DC converters 6 to the CPU 5 through one pillar 4A and the plurality of through holes 21A.

  One pillar 4B and one DC / DC converter 6 may be electrically connected. Therefore, the ground voltage may be supplied from one DC / DC converter 6 to the CPU 5 through one pillar 4B and a plurality of through holes 21B. One pillar 4B and a plurality of DC / DC converters 6 may be electrically connected. Therefore, the ground voltage may be supplied from the plurality of DC / DC converters 6 to the CPU 5 through one pillar 4B and the plurality of through holes 21B.

  A signal transmission path 22 is not formed on the power supply substrate 3. Therefore, the wiring pattern in the inner layer of the power supply substrate 3 is not affected by the arrangement of the signal transmission path 22. That is, all the inner layers of the power supply substrate 3 can be used as a power feeding path. Since the power supply wiring 35 and the ground wiring 36 are not formed on the main board 2, power supply noise from the power supply path to the signal transmission path 22 of the main board 2 can be reduced.

  A CPU 5 is mounted on the upper surface of the main board 2. Therefore, it is required that the flatness of the joint surface between the main board 2 and the CPU 5 is good. When the flatness is not good, the distance between the upper surface of the main board 2 and the CPU 5 is not uniform. In this case, the bonding state between the solder balls 11 on the upper surface of the main board 2 and the CPU 5 becomes poor, and the power supply to the CPU 5 becomes unstable.

  For example, there is a case where power is supplied to the CPU 5 by forming a through hole having a large diameter in the main board 2 and embedding a copper pillar or a copper coin in the through hole. However, if a through hole having a large diameter is formed in the main board 2, the main board 2 is distorted, and the flatness of the joint surface between the main board 2 and the CPU 5 is deteriorated. Further, when a copper pillar or a copper coin is embedded in the main board 2, the manufacturing cost of the main board 2 increases. As described above, when power is supplied to the CPU 5 by embedding copper pillars or copper coins in the main board 2, there is a great disadvantage.

  Formation of the through holes 21 included in the main board 2 is easy, and even if a plurality of through holes 21 are formed in the main board 2, the main board 2 is not distorted or warped. That is, the diameter of the through hole 21 is smaller than the diameter of the pillar 4, and the diameter of the through hole 21 is adjusted so that the main board 2 is not distorted or warped. Since the cross-sectional area of the single through hole 21 is small, the power supplied to the CPU 5 through the single through hole 21 is small. Therefore, when one solder ball 11 and one through hole 21 are joined, the power supplied to the CPU 5 may be insufficient.

  According to the power supply substrate 1, the power supplied to the CPU 5 can be increased by increasing the number of through holes 21 than the number of solder balls 11. A surface pattern 23 is disposed at the interface (joint portion) between the solder ball 11 and the through hole 21. Thereby, the plurality of through holes 21 are electrically connected to one solder ball 11, and the power supplied to the CPU 5 can be increased. Therefore, according to the power supply substrate 1, a large current can be supplied from the DC / DC converter 6 to the CPU 5 through the plurality of pillars 4 and the plurality of through holes 21.

  In the power supply board 1, a DC / DC converter 6 is arranged on the power board 3. Therefore, when the power consumption of the CPU 5 is increased and the number of DC / DC converters 6 is increased, the DC / DC converter 6 can be added without using the mounting area of the main board 2. Since the connection between the main board 2 and the pillar 4 is performed by SMT, the design of the main board 2 and the pillar 4 is simplified. Moreover, since the cross-sectional area of the pillar 4 is large, a voltage drop in the power supply path from the DC / DC converter 6 to the CPU 5 can be suppressed.

  FIG. 6 is a diagram showing an interface between the main board 2 and the CPU 5. A rectangle 61 in FIG. 6 is an outer shape portion of the CPU 5. The CPU 5 includes a power supply unit 62 and a plurality of signal transmission units 63. The power supply unit 62 supplies the power supplied from the DC / DC converter 6 to various parts of the CPU 5. The signal transmission unit 63 is connected to the signal transmission path 22 of the main board 2. The signal transmission unit 63 receives a signal from the signal transmission path 22 of the main board 2 and transmits a signal to the signal transmission path 22 of the main board 2.

  As shown in FIG. 6, a power feeding unit 62 is disposed in the central portion of the CPU 5, and a plurality of signal transmission units 63 are disposed on the outer peripheral portion outside the central portion of the CPU 5. That is, the power feeding unit 62 and the plurality of signal transmission units 63 are arranged separately. Pillars 4 </ b> A and 4 </ b> B are disposed immediately below the central portion of the CPU 5, and the signal transmission path 22 of the main board 2 is disposed immediately below the outer peripheral portion of the CPU 5. Therefore, the signal transmission path 22 of the main board 2 and the power supply path from the DC / DC converter 6 to the CPU 5 can be separated, and power supply noise from the power supply path to the signal transmission path 22 of the main board 2 can be reduced. Can do.

<Example 2>
A power supply board 1 according to a second embodiment will be described. In the power supply board 1 according to the second embodiment, the main board 2 and the power board 3 are connected by a connector. 7 and 8 are explanatory diagrams of a method for connecting the main board 2 and the power supply board 3. The main board 2 is provided with a plurality of first connectors 71 instead of the plurality of pillars 4. A plurality of first connectors are mounted on the lower surface of the main board 2 by SMT.

The power supply board 3 is provided with a plurality of second connectors. The second connector is connected (fitted) to the first connector 71. The first connector 71 is, for example, a male connector. The second connector 72 is, for example, a female connector. The first connector 71 and the second connector 72 are formed using, for example, copper. The first connector 7 is not limited to the example shown in FIGS.
1 may be a female connector, and the second connector 72 may be a male connector.

  When the pillar 4 is mounted on the power supply board 3 by the DIP method, in order to remove the pillar 4 from the power supply board 3, the solder 37 is remelted and the pillar 4 is pulled out from the through holes 31 and 32. Therefore, an extra thermal load is applied to the power supply board 1. By connecting the main board 2 and the power supply board 3 by the first connector 71 and the second connector 72, the main board 2 and the power supply board 3 can be easily separated. Therefore, it becomes easy to repeat the connection and separation between the main board 2 and the power supply board 3, and the maintainability of the power supply board 1 is improved.

  For example, when the entire pillar 4 has a cylindrical shape, as shown in FIG. 13, the distance between the main board 2 and the power supply board 3 is not fixed, and positioning of the power supply board 3 becomes difficult, or the power supply board 3 There is a problem that positioning cannot be performed. Further, when the diameter of the through hole 31 is large, the power supply board 3 is not parallel to the main board 2, and an electronic component 81 such as a capacitor mounted on the main board 2 and a capacitor mounted on the power supply board 3 are not used. There is a problem that the distance to the electronic component 82 is not constant. The distance between the electronic component 81 of the main board 2 and the electronic component 82 of the power board 3 varies according to the distance between the main board 2 and the power board 3. If the main board 2 and the power supply board 3 are too close, the electronic component 81 of the main board 2 and the electronic component 82 of the power supply board 3 may come into contact with each other.

  In the power supply board 1 according to the first embodiment, the pillar 4A includes a first portion having a first diameter (diameter) and a second portion having a second diameter (diameter). The first part and the second part of the pillar 4A have a cylindrical shape, and the first part and the second part of the pillar 4A are connected. The diameter of the first part of the pillar 4A is larger than the diameter of the second part of the pillar 4A. As shown in FIG. 14, the first portion of the pillar 4 </ b> A is mounted on the main board 2 in a state where the end surface of the first portion of the pillar 4 </ b> A is in contact with the surface pattern 24. FIG. 14 is a schematic diagram of the power supply board 1 before the pillar 4A is mounted on the power supply board 3. FIG. The end surface of the second portion of the pillar 4A is directed to the power supply substrate 3 side. Since the diameter of the first portion of the pillar 4A is larger than the diameter of the second portion of the pillar 4A, the pillar 4A has a step shape. In other words, the pillar 4A has a shape in which a central portion of one end face of the pillar 4 protrudes. The electronic component 81 is mounted on the lower surface of the main board 2, and the electronic component 82 is mounted on the upper surface of the power supply substrate 3.

  FIG. 15 is a schematic diagram of the power supply board 1 when the pillar 4 </ b> A is mounted on the power board 3. As shown in FIG. 15, the first part of the pillar 4 </ b> A is located between the main board 2 and the power supply board 3, and the second part of the pillar 4 </ b> A is located inside the power supply board 3. Since the pillar 4 </ b> A has a step shape, the first part of the pillar 4 </ b> A contacts the upper surface of the power supply substrate 3, and the second part of the pillar 4 </ b> A is inserted into the hole of the through hole 31 that penetrates the power supply substrate 3. The through hole 31 is an example of a third through hole. The hole of the through hole 31 has a circular shape in plan view. Since the diameter of the second portion of the pillar 4 </ b> A is smaller than the diameter (diameter) of the through hole 31, a gap (space) is formed between the second portion of the pillar 4 </ b> A and the through hole 31. By forming the solder 37 in the gap between the second part of the pillar 4A and the through hole 31, the second part of the pillar 4A and the through hole 31 are joined.

Due to the step shape of the pillar 4A, the power supply substrate 3 is held at a fixed position (a position away from the main board 2 by a predetermined length). That is, the first portion of the pillar 4A and the upper surface of the power supply substrate 3 are in contact with each other, and the second portion of the pillar 4A and the through hole 31 are joined, whereby the power supply substrate 3 is held at a fixed position. Since the diameter of the first portion of the pillar 4 </ b> A is larger than the diameter of the through hole 31, the first portion of the pillar 4 </ b> A and the upper surface of the power supply substrate 3 are in contact with each other. When the first portion of the pillar 4 </ b> A and the upper surface of the power supply board 3 are in contact with each other, the power supply board 3 is parallel to the main board 2, and the power supply board 3 is not inclined with respect to the main board 2. By holding the power supply board 3 at a fixed position, the distance between the electronic component 81 of the main board 2 and the electronic component 82 of the power supply board 3 becomes constant. According to the power supply board 1 according to the first embodiment, the power supply board 3 can be easily positioned, and the distance between the main board 2 and the power supply board 3 can be kept constant. Therefore, the distance between the electronic component 81 of the main board 2 and the electronic component 82 of the power supply board 3 can be kept constant.

  It is possible to adjust the distance between the main board 2 and the power supply board 3 by changing the length of the first portion of the pillar 4A. By making the length of the first portion of the pillar 4A larger than the total value of the height of the electronic component 81 and the height of the electronic component 82, contact between the electronic component 81 and the electronic component 82 can be avoided.

  14 and 15, the pillar 4A is illustrated and the pillar 4B is not illustrated, but the pillar 4B may have the same configuration as the pillar 4A. That is, the pillar 4B may include a first portion having a first diameter (diameter) and a second portion having a second diameter (diameter). The first part and the second part of the pillar 4B have a cylindrical shape, and the first part and the second part of the pillar 4B are connected to each other. The diameter of the first part of the pillar 4B is larger than the diameter of the second part of the pillar 4B. Since the diameter of the first portion of the pillar 4B is larger than the diameter of the second portion of the pillar 4B, the pillar 4B has a step shape. In other words, the pillar 4B has a shape in which a central portion of one end face of the pillar B protrudes. When the pillar 4B is mounted on the power supply board 3, the first part of the pillar 4B is located between the main board 2 and the power supply board 3, and the second part of the pillar 4B is located inside the power supply board 3. .

  Since the pillar 4B has a stepped shape, the first part of the pillar 4B comes into contact with the upper surface of the power supply substrate 3, and the second part of the pillar 4B is inserted into the hole of the through hole 32 that penetrates the power supply substrate 3. The through hole 32 is an example of a fourth through hole. The hole of the through hole 32 has a circular shape in plan view. Since the diameter of the second part of the pillar 4B is smaller than the diameter (diameter) of the through hole 32, a gap (space) is formed between the second part of the pillar 4B and the through hole 32. By forming the solder 37 in the gap between the second portion of the pillar 4B and the through hole 32, the second portion of the pillar 4B and the through hole 32 are joined. The first portion of the pillar 4B and the upper surface of the power supply substrate 3 are in contact with each other, and the second portion of the pillar 4B and the through hole 32 are joined, whereby the power supply substrate 3 is held at a fixed position. Since the diameter of the first portion of the pillar 4B is larger than the diameter of the through hole 32, the first portion of the pillar 4B and the upper surface of the power supply substrate 3 are in contact with each other.

  One of the pillars 4A and 4B may have a step shape, or both the pillars 4A and 4B may have a step shape. Since at least one of the pillars 4 </ b> A and 4 </ b> B has a step shape, the power supply board 3 is held at a fixed position, and the distance between the main board 2 and the power supply board 3 can be made constant. Since both pillars 4 </ b> A and 4 </ b> B have stepped shapes, the accuracy of the parallelism of the power supply substrate 3 with respect to the main board 2 is improved. Moreover, at least one pillar 4A among the plurality of pillars 4A may have a step shape, or all of the plurality of pillars 4A may have a step shape. Since two or more pillars 4A among the plurality of pillars 4A have the step shape, the accuracy of the parallelism of the power supply substrate 3 with respect to the main board 2 is improved. Furthermore, at least one pillar 4B among the plurality of pillars 4B may have a step shape, or all of the plurality of pillars 4B may have a step shape. Since two or more pillars 4B among the plurality of pillars 4B have a step shape, the accuracy of the parallelism of the power supply substrate 3 with respect to the main board 2 is improved.

<Example 3>
As shown in FIG. 1, since power is supplied from the DC / DC converter 6 to the CPU 5 via the pillar 4, a large current can be supplied from the DC / DC converter 6 to the CPU 5. The electric power generated by the DC / DC converter 6 passes through the wiring pattern in the inner layer of the power supply board 3 and is supplied to the CPU 5 through the outer peripheral surface of the pillar 4 and the pillar 4. A through hole 21 for supplying power from the pillar 4 to the CPU 5 is formed in the main board 2. A plurality of through holes 21 are formed in the main board 2 to supply a large current to the CPU 5.

  Since the current that can flow through one through hole 21 is limited, the number of through holes 21 increases to supply a large current to the CPU 5. In order to pass a current from the pillar 4 to the plurality of through holes 21, the pillar 4 and the plurality of through holes 21 come into contact with each other, so that the outer diameter of the pillar 4 increases according to the number of the through holes 21. In order to increase the strength of the solder 25 (solder joint) that joins the main board 2 and the pillar 4, it is effective to increase the joint area of the solder 25. As the outer diameter of the pillar 4 increases, the bonding area of the solder 25 increases.

  On the other hand, when the outer diameter of the pillar 4 is increased, the rigidity of the pillar 4 is increased. When the rigidity of the pillar 4 is increased, cracks (cracks) occur in the solder 25 that joins the main board 2 and the pillar 4 for the following reason.

  When the server apparatus including the power supply board 1 is turned on and the server apparatus is operated, the temperature in the server apparatus is increased. When the server apparatus is turned off and the server apparatus is stopped, the temperature in the server apparatus is decreased. Become. When the temperature inside the server device increases, the main board 2 and the power supply board 3 expand, and when the temperature inside the server device decreases, the main board 2 and the power supply board 3 contract. FIG. 16 is a schematic diagram of the power supply board 1 when the main board 2 expands and the power supply board 3 expands when the server device is in an operating state.

  The thermal expansion coefficient of the main board 2 and the thermal expansion coefficient of the power supply substrate 3 are different depending on the substrate characteristics (substrate material, type, thickness, number of inner layers). Therefore, the contraction speed of the main board 2 and the contraction speed of the power supply substrate 3 are different. For example, when the contraction speed of the power supply board 3 is faster than the contraction speed of the main board 2, the pillars 4A and 4B mounted on the main board 2 and the power supply board 3 follow the behavior of the main board 2 and the power supply board 3, respectively. As a result, stress is generated around the pillars 4A and 4B. FIG. 17 is a schematic diagram of the power supply board 1 when the contraction speed of the power supply board 3 is faster than the contraction speed of the main board 2.

  When the pillars 4A and 4B have low rigidity, when the pillars 4A and 4B follow the respective behaviors of the main board 2 and the power supply board 3, the pillars 4A and 4B bend, so that the stress generated in the solder 25 is relieved. Is done. However, as described above, when the outer diameters of the pillars 4A and 4B are increased, the rigidity of the pillars 4A and 4B is increased. Therefore, the stress generated in the solder 25 is increased, and a crack is generated on the joint surface of the solder 25. FIG. 18 is a schematic diagram of the power supply substrate 1 and shows stress generation locations.

  When the outer diameters of the pillars 4A and 4B are reduced, the rigidity of the pillars 4A and 4B is lowered. In order to relieve the stress generated in the solder 25, as shown in FIG. 19, a coping method for reducing the outer diameter of the pillars 4A and 4B is conceivable. However, if the outer diameter of the pillar 4A is reduced, the bonding area (contact area) between the pillar 4A and the through hole 21A is reduced. If the outer diameter of the pillar 4B is reduced, the bonding area (contact) between the pillar 4B and the through hole 21B is reduced. Area) decreases. Therefore, there is a possibility that power supply to the CPU 5 is insufficient. Further, when the outer diameter of the pillars 4A and 4B is reduced, the bonding area of the solder 25 may be reduced, so that the bonding strength of the solder 25 may be reduced.

A power supply board 1 according to a third embodiment will be described. FIG. 20 is a schematic diagram of the power supply substrate 1. FIG. 21 is an external view of the pillar 4A, and shows a side surface and a bottom surface of the pillar 4A. The pillar 4A includes a first portion 91A mounted on the main board 2 and a second portion 92A mounted on the power supply board 3. The second portion 92 </ b> A of the pillar 4 </ b> A is inserted into the hole of the through hole 31 that penetrates the power supply substrate 3. The first portion 91A of the pillar 4A includes a first pillar portion 93A, a second pillar portion 94A, and a third pillar portion 95A formed (arranged) between the first pillar portion 93A and the second pillar portion 94A. including.

  The first pillar portion 93 </ b> A of the pillar 4 </ b> A is mounted on the lower surface of the main board 2. The second pillar portion 94A of the pillar 4A is connected to the second portion 92A of the pillar 4A. Further, the second pillar portion 94 </ b> A of the pillar 4 </ b> A is in contact (connected) with the upper surface of the power supply substrate 3. The outer diameter (first diameter) of the first pillar portion 93A of the pillar 4A and the outer diameter (second diameter) of the second pillar portion 94A of the pillar 4A are the same size. The outer diameter (D1 in FIG. 21) of the first pillar portion 93A of the pillar 4A is, for example, Φ7 mm. The outer diameter (D2 in FIG. 21) of the second pillar portion 94A of the pillar 4A is, for example, Φ7 mm. The thickness (T1 in FIG. 21) of the first pillar portion 93A of the pillar 4A is, for example, 1 mm. The thickness of the second pillar portion 94A of the pillar 4A (T2 in FIG. 21) is, for example, 1 mm. The outer diameter of the second pillar portion 94A of the pillar 4A is larger than the outer diameter of the second portion 92A of the pillar 4A. Therefore, since the pillar 4A has a bowl shape (step shape), the pillar 4A is prevented from falling off during manufacturing.

  The third diameter of the third pillar portion 95A of the pillar 4A is smaller than the first diameter of the first pillar portion 93A of the pillar 4A and the second diameter of the second pillar portion 94A of the pillar 4A. The third diameter (D3 in FIG. 21) of the third pillar portion 95A of the pillar 4A is, for example, Φ6 mm. Therefore, in the first portion 91A of the pillar 4A, an intermediate portion (third column portion 95A) between the upper portion (first column portion 93A) and the lower portion (second column portion 94A) is narrowed. When the cross-sectional area of the third pillar portion 95A of the pillar 4A secures an area capable of supplying power used by the CPU 5, the third diameter of the third pillar portion 95A of the pillar 4A is made as small as possible. May be. The thickness (T3 in FIG. 21) of the third pillar portion 95A of the pillar 4A is, for example, 5 mm.

  FIG. 22 is an external view of the pillar 4B, and shows a side surface and a bottom surface of the pillar 4B. The pillar 4 </ b> B has a first portion 91 </ b> B mounted on the main board 2 and a second portion 92 </ b> B mounted on the power supply board 3. The second portion 92B of the pillar 4B is inserted into the hole of the through hole 32 that penetrates the power supply substrate 3. The first portion 91B of the pillar 4B includes a first pillar portion 93B, a second pillar portion 94B, and a third pillar portion 95B formed (arranged) between the first pillar portion 93B and the second pillar portion 94B. including.

  The first pillar portion 93 </ b> B of the pillar 4 </ b> B is mounted on the lower surface of the main board 2. The second pillar portion 94B of the pillar 4B is connected to the second portion 92B of the pillar 4B. Further, the second pillar portion 94 </ b> B of the pillar 4 </ b> B is in contact (connected) with the upper surface of the power supply substrate 3. The outer diameter (first diameter) of the first pillar portion 93B of the pillar 4B and the outer diameter (second diameter) of the second pillar portion 94B of the pillar 4B are the same size. The outer diameter (D4 in FIG. 22) of the first pillar portion 93B of the pillar 4B is, for example, Φ7 mm. The outer diameter (D5 in FIG. 22) of the second pillar portion 94B of the pillar 4B is, for example, Φ7 mm. The thickness of the first pillar portion 93B of the pillar 4B (T4 in FIG. 22) is, for example, 1 mm. The thickness (T5 in FIG. 22) of the second pillar portion 94B of the pillar 4B is, for example, 1 mm. The outer diameter of the second pillar portion 94B of the pillar 4B is larger than the outer diameter of the second portion 92B of the pillar 4B. Accordingly, since the pillar 4B has a bowl shape (step shape), the pillar 4B is prevented from falling off during manufacturing.

The third diameter of the third pillar portion 95B of the pillar 4B is smaller than the first diameter of the first pillar portion 93B of the pillar 4B and the second diameter of the second pillar portion 94B of the pillar 4B. The third diameter (D6 in FIG. 22) of the third pillar portion 95B of the pillar 4B is, for example, Φ6 mm. Accordingly, the first portion 91B of the pillar 4B has a thin intermediate portion (third column portion 95B) between the upper portion (first column portion 93B) and the lower portion (second column portion 94B). When the cross-sectional area of the third pillar portion 95B of the pillar 4B secures an area capable of supplying power used by the CPU 5, the third diameter of the third pillar portion 95B of the pillar 4B is made as small as possible. May be. The thickness (T6 in FIG. 22) of the third pillar portion 95B of the pillar 4B is, for example, 5 mm.

The rigidity of the pillars 4A and 4B can be expressed by a cross-sectional second moment in terms of material mechanics. The greater the value of the moment of inertia of the cross section, the higher the rigidity. The circular sectional second moment I is obtained by the following equation 1.
I = πd4 / 64 Equation 1
d is the diameter of the pillar 4A or 4B.

  When the value of the diameter of the pillar 4A according to the first embodiment (d = Φ7 mm) is substituted into the formula 1, the value of the cross-sectional second moment of the pillar 4A according to the first embodiment is I = 1117.8. The pillar 4A according to the first embodiment has a straight shape in which an intermediate portion between the upper portion and the lower portion is not thinned. When the value of the diameter (d = Φ6 mm) of the third column portion 95A of the pillar 4A according to the third embodiment is substituted into the expression 1, the sectional second moment of the third column portion 95A of the pillar 4A according to the third embodiment. The value of I = 63.6. Therefore, the value of the cross-sectional secondary moment of the third pillar portion 95A of the pillar 4A according to the third embodiment is reduced to about 54% of the value of the cross-sectional second moment of the pillar 4A according to the first embodiment. From this result, it can be seen that the rigidity of the pillar 4A according to the third embodiment is lower than the rigidity of the pillar 4A according to the first embodiment. Here, the pillar 4A is described, but the pillar 4B has the same shape as the pillar 4A, so the pillar 4B has the same result as the pillar 4A, and the pillar 4B according to the third embodiment has the same result. The rigidity is lower than the rigidity of the pillar 4B according to the first embodiment.

As a result of analyzing the stress generated in the solder 25 according to the first embodiment and analyzing the stress generated in the solder 25 according to the third embodiment, the stress generated in the solder 25 according to the third embodiment is reduced. It was confirmed. The stress analysis conditions and results are shown below.
Analysis condition: temperature difference in server device = 65 ° C.
The temperature difference in the server device is a difference between the maximum temperature when the temperature in the server device increases and the minimum temperature when the temperature in the server device decreases.
Analysis result 1: Stress generated in the solder 25 according to Example 1 = 28.69 MPa (maximum value)
Analysis result 2: Stress generated in the solder 25 according to Example 3 = 25.99 MPa (maximum value)
From the analysis result 1 and the analysis result 2, it can be seen that the stress generated in the solder 25 according to Example 3 is reduced by about 9%.

  FIG. 21 shows an example in which the outer diameter of the second pillar portion 94A of the pillar 4A is larger than the outer diameter of the second portion 92A of the pillar 4A. The third embodiment is not limited to the example illustrated in FIG. 21, and the outer diameter of the second pillar portion 94A of the pillar 4A and the outer diameter of the second portion 92A of the pillar 4A may be the same size. FIG. 22 shows an example in which the outer diameter of the second pillar portion 94B of the pillar 4B is larger than the outer diameter of the second portion 92B of the pillar 4B. The third embodiment is not limited to the example illustrated in FIG. 22, and the outer diameter of the second pillar portion 94B of the pillar 4B and the outer diameter of the second portion 92B of the pillar 4B may be the same size.

  According to the power supply substrate 1 according to the third embodiment, the pillar 4A includes the third column portion 95A that is narrower than the first column portion 93A and the second column portion 94A, thereby reducing the stress generated in the solder 25. be able to. The outer diameter of the first pillar portion 93A of the pillar 4A is not small. Therefore, the bonding area between the pillar 4A and the through hole 21A is not reduced, and the bonding area of the solder 25 is not reduced. Therefore, according to the power supply substrate 1 according to the third embodiment, it is possible to maintain the bonding strength of the solder 25 while avoiding a shortage of power supply to the CPU 5.

  According to the power supply substrate 1 according to the third embodiment, the pillar 4B includes the third column portion 95B that is narrower than the first column portion 93B and the second column portion 94B, thereby reducing the stress generated in the solder 25. be able to. The outer diameter of the first pillar portion 93B of the pillar 4B is not small. Therefore, the bonding area between the pillar 4B and the through hole 21B is not reduced, and the bonding area of the solder 25 is not reduced. Therefore, according to the power supply substrate 1 according to the third embodiment, it is possible to maintain the bonding strength of the solder 25 while avoiding a shortage of power supply to the CPU 5.

1 Power supply board 2 Main board 3 Power supply board 4 Pillar 5 CPU
6 DC / DC converter 11 Solder balls 21, 31, 32, 33, 34 Through hole 22 Signal transmission path 23, 24 Surface pattern 25, 37 Solder 35 Power supply wiring 36 Ground wiring 71 First connector 72 Second connector 81, 82 Electron parts

Claims (7)

A top surface on which a processor can be mounted, a bottom surface opposite to the top surface, and a plurality of first through holes and a plurality of second through holes that penetrate the bottom surface from the top surface and are electrically connected to the processor. 1 substrate,
A second substrate disposed at a position away from the lower surface of the first substrate and having a power supply device;
A first conductor mounted on the lower surface of the first substrate and electrically connecting the plurality of first through holes and the power supply device;
A second conductor mounted on the lower surface of the first substrate and electrically connecting the plurality of second through holes and the power supply device;
Equipped with a,
The first conductor includes a first portion mounted on the lower surface of the first substrate, and a second portion inserted into a hole of a third through hole penetrating the second substrate,
A diameter of the first portion of the first conductor is larger than a diameter of the hole of the third through hole . A power supply voltage is supplied from the power supply device to the processor through the first through hole and the first conductor.
The power supply board according to claim 1, wherein a ground voltage is supplied from the power supply device to the processor through the second through hole and the second conductor. The first conductor is disposed immediately below a plurality of the first through holes and in a central portion of the second substrate,
The second conductor is disposed immediately below the plurality of second through holes and in the central portion of the second substrate,
3. The power supply board according to claim 1, wherein the power supply device is disposed on an outer peripheral portion of the second substrate outside the central portion. The second conductor includes a third portion mounted on the lower surface of the first substrate, and a fourth portion inserted into a hole of a fourth through hole penetrating the second substrate.
4. The power supply board according to claim 1, wherein a diameter of the third portion of the second conductor is larger than a diameter of the hole of the fourth through hole. The first conductor includes a first pillar portion mounted on the lower surface of the first substrate, a second pillar portion in contact with the second substrate, and between the first pillar portion and the second pillar portion. And a third pillar portion formed in
The diameter of the third column portion includes a power supply substrate according to claim 1, any one of 4, wherein the smaller than the diameter and the diameter of the second columnar portion of the first pillar portion. The second conductor includes a fourth pillar portion mounted on the lower surface of the first substrate, a fifth pillar portion in contact with the second substrate, and between the fourth pillar portion and the fifth pillar portion. And a sixth pillar portion formed in
The diameter of the sixth column portion, the power supply substrate according to claim 1, any one of 5, wherein the smaller than the diameter of the diameter and the fifth pillar part of the fourth pillar part. A top surface on which a processor can be mounted, a bottom surface opposite to the top surface, and a plurality of first through holes and a plurality of second through holes that penetrate the bottom surface from the top surface and are electrically connected to the processor. 1 substrate,
A second substrate disposed at a position away from the lower surface of the first substrate and having a power supply device;
A first conductor mounted on the lower surface of the first substrate and electrically connecting the plurality of first through holes and the power supply device;
A second conductor mounted on the lower surface of the first substrate and electrically connecting the plurality of second through holes and the power supply device;
With
The second conductor includes a first portion mounted on the lower surface of the first substrate, and a second portion inserted into a hole of a fourth through hole penetrating the second substrate,
The diameter of the said 1st part of a said 2nd conductor is larger than the diameter of the said hole which the said 4th through hole has, The power supply board characterized by the above-mentioned.

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