CN212628563U

CN212628563U - Circuit board assembly and server with same

Info

Publication number: CN212628563U
Application number: CN202021464782.1U
Authority: CN
Inventors: 贺潇; 郝明亮; 彭浩; 李忠信; 何叶
Original assignee: Bitmain Technologies Inc
Current assignee: Bitmain Technologies Inc
Priority date: 2020-07-22
Filing date: 2020-07-22
Publication date: 2021-02-26
Anticipated expiration: 2030-07-22

Abstract

The utility model discloses a circuit board assembly and server that has it, circuit board assembly includes: PCB board, a plurality of chip and a plurality of fin, the PCB board includes: the heat conduction plate comprises a main plate body, a medium layer, a conductive layer and a plurality of heat conduction blocks, wherein the main plate body comprises a middle plate and heat conduction layers arranged on two sides of the middle plate; the medium layer is distributed on one side of the main board body; the conducting layer and the dielectric layer are positioned on the same side of the main plate body, and the conducting layer are bonded through the dielectric layer; the heat conducting block is of a solid structure and is embedded in the PCB; the chip, the conducting layer and the medium layer are positioned on the same side of the main plate body, and the heat conducting block penetrates through the conducting layer to be in contact with the chip positioned on the outer side of the conducting layer; the radiating fins are connected to one side of the PCB, which is far away from the chip, and are in one-to-one correspondence with the heat conducting blocks. Like this, the chip below is all by the heat conduction piece intercommunication to the back of PCB board, has dredged the hot route of chip bottom, makes better the releasing of heat to the heat conduction piece through the chip bottom, has promoted the holistic heat-sinking capability of subassembly.

Description

Circuit board assembly and server with same

Technical Field

The utility model belongs to the technical field of the circuit board heat dissipation and specifically relates to a circuit board assembly and have its server is related to.

Background

As shown in fig. 1, a layer of stainless steel or copper shell may be added on the outer surface of the bare chip 21 ' and the plastic package 26 ', the bare chip 21 ' is connected to the substrate 23 ' through the contact bumps 22 ', and the substrate 23 ' is connected to the PCB board through the LGA pins 25 '. The heat source conducts a portion of the heat through the bare die 21 'to the upper surface and may transfer the heat into the air by adding a heat sink over the chip 20' to enhance heat dissipation; on the other hand, a part of the heat is also conducted into the PCB board through the contact bumps 22 ', the substrate 23 ' and the heat conducting disc 24 '.

The heat conduction path of the chip 20 'mainly includes an upper path and a lower path, the heat on the upper surface is conducted to the upper surface of the chip 20' through the bare wafer 21 ', and the thermal resistance from the heat source to the upper surface of the chip 20' is recorded as Rjc; next, heat first passes through the contact bumps 22 ', the substrate 23 ' and the thermally conductive pad 24 ', which together have a thermal resistance designated Rjb, and then the heat is conducted into the PCB, which has a thermal resistance designated Rpcb from top to bottom.

Since the thermal resistance is inversely proportional to the thermal conductivity of the material, the heat transfer area, and directly proportional to the material thickness, the main directions for improving Rjc are to reduce the thickness of the bare wafer 21 'and increase the area of the bare wafer 21'; the main direction of improvement Rjb is to increase the thermal conductivity of the contact bumps 22 ', the substrate 23', increase its area and reduce its thickness, and the main direction of improvement Rpcb is to increase the thermal conductivity of the PCB while reducing the thickness of the PCB. Therefore, reducing Rpcb is primarily to increase the copper content of the PCB, especially the copper content of the PCB directly under the chip 20'.

As shown in fig. 2, the PCB includes an intermediate plate 11 ', a heat conducting layer 13 ', a dielectric layer 12 ', and a conductive layer 15 ' sequentially arranged from inside to outside, and the PCB is connected to the chip 20 ' by soldering. Fig. 2 shows a conventional method for increasing the thermal conductivity of a PCB, i.e. adding a hollow copper pillar 17 ' (i.e. a thermal via hole) in the PCB below a thermal pad 24 ' of a chip 20 ', which can increase the copper content in a local area of the PCB to more than 10%, and increase the thermal conductivity of the PCB with a thermal conductivity of 0.3W/(mK) to more than 40W/(mK). The heat resistance from the PCB to the air is further reduced and the heat dissipation capability of the back of the PCB is enhanced by welding the radiator on the back of the PCB. The limitation of this method is that the density of the thermal via holes cannot be increased infinitely due to the process limitation, so that the improvement of the copper content is limited and the thermal conductivity of the local area and the copper metal cannot reach the same level.

As shown in fig. 3, for another method for improving the thermal conductivity of the PCB, under the heat conducting plate 24 ' of the chip 20 ', the solid copper pillar 16 ' is added to the dielectric layer 12 ', and the hollow copper pillar 17 ' (thermal via hole) is added to the FR4 region, so that the copper content in the local region of the PCB can be improved to more than 20%, and the thermal conductivity of the region of the PCB with the thermal conductivity of 0.3W/(mK) can be improved to more than 90W/(mK).

The heat resistance from the PCB to the air is further reduced and the heat dissipation capability of the back of the PCB is enhanced by welding the heat dissipation fins on the back of the PCB. The limitation of this method is that no matter the density of copper pillars or thermal vias is not infinitely increased, there is a limit to the improvement of copper content, and the thermal conductivity of the local area cannot reach the same level as that of copper or aluminum.

SUMMERY OF THE UTILITY MODEL

The utility model discloses aim at solving one of the technical problem that exists among the prior art at least. To this end, an object of the present invention is to provide a circuit board assembly.

According to the utility model discloses circuit board assembly of first aspect embodiment includes: PCB board, a plurality of chip and a plurality of fin, the PCB board includes: the heat conducting plate comprises a main plate body, a medium layer, a conducting layer and a plurality of heat conducting blocks, wherein the main plate body comprises a middle plate and heat conducting layers arranged on two sides of the middle plate; the dielectric layer is made of insulating materials and is distributed on one side of the main board body; the conducting layer and the dielectric layer are positioned on the same side of the main plate body, and the heat conducting layer is bonded with the conducting layer through the dielectric layer; the heat conduction block is of a solid structure and is embedded in the PCB; the plurality of chips, the conducting layer and the medium layer are positioned on the same side of the main board body, the chips are fixed with the PCB and electrically connected with the conducting layer, and each heat conducting block penetrates through the conducting layer to be in contact with the chip positioned on the outer side of the conducting layer; the radiating fins are connected to one side of the PCB, which is far away from the chip, and are in one-to-one correspondence with the heat conducting blocks.

According to the utility model discloses circuit board assembly, through burying a plurality of heat conduction pieces that the components of a whole that can function independently set up underground at the PCB inboard, every heat conduction piece corresponds a chip so that the heat of chip is direct transmits the fin through the heat conduction piece, and the chip below is whole by the heat conduction piece intercommunication to the back of PCB board like this, has dredged the hot route of chip bottom, makes the heat can be better release to the heat conduction piece through the chip bottom, has promoted the holistic heat-sinking capability of subassembly, has reduced the temperature of chip.

In some embodiments, the width of the area corresponding to each chip and the heat conduction block is 1/2-1 times the width of the chip.

In some embodiments, the heat conduction blocks, the heat conduction layer and the conductive layer are made of copper materials, a plurality of the heat conduction blocks are arranged at intervals, and the plurality of the heat conduction blocks are correspondingly welded with the heat conduction plates of a plurality of chips.

In some embodiments, the thermal resistance of the PCB is 0.4-0.5K/W, and the equivalent thermal conductivity of the PCB in the thickness direction is 300-400W/(mK).

According to the utility model discloses circuit board assembly of second aspect embodiment includes: PCB board, a plurality of chip and a plurality of fin, the PCB board includes: the heat-conducting plate comprises a main plate body, a medium layer, a conducting layer and heat-conducting pieces, wherein the main plate body comprises a middle plate and heat-conducting layers arranged on two sides of the middle plate, and the heat-conducting layers are grounding layers; the dielectric layer is made of insulating materials and is distributed on one side of the main board body; the conducting layer and the dielectric layer are positioned on the same side of the main plate body, and the heat conducting layer is bonded with the conducting layer through the dielectric layer; the heat conducting part comprises a main heat conducting part and a plurality of auxiliary heat conducting parts, the main heat conducting part corresponds to a plurality of chips positioned at the same power supply voltage, and each auxiliary heat conducting part is contacted with the conductive layer or a corresponding chip; the chips, the conducting layer and the medium layer are positioned on the same side of the main board body, the chips are fixed with the PCB and electrically connected with the conducting layer, and the auxiliary heat conducting element is in contact with the conducting layer or the chips; the radiating fins are connected to one side of the PCB, which is far away from the chip, and are in one-to-one correspondence with the heat conducting blocks.

In some embodiments, the secondary thermal conductive members are copper blocks, and each chip corresponds to one of the secondary thermal conductive members.

In some embodiments, the secondary thermal conduction member has a plurality of micro-holes disposed perpendicular to the main plate body.

In some embodiments, the pores have a diameter of 4mil to 6mil and the dielectric layer has a thickness of 2mil to 5 mil.

In some embodiments, the width of the area of the secondary thermal conduction member corresponding to the chip is 1/2-1 times the width of the chip.

According to the utility model discloses third aspect embodiment's server includes: the fan comprises a box body, a plurality of circuit board assemblies and a fan, wherein the circuit board assemblies are arranged in the box body and are sequentially arranged along the width direction of the box body; the fans are arranged at two ends of the box body in the length direction, the fan at one end is formed into an air supply fan, and the fan at the other end is formed into an air exhaust fan.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a schematic diagram of a prior art chip.

Fig. 2 is a schematic diagram of a prior art circuit board assembly.

Fig. 3 is a schematic diagram of another prior art circuit board assembly.

Fig. 4 is a schematic diagram of a circuit board assembly according to an embodiment of the present invention.

Fig. 5 is a schematic diagram of a circuit board assembly according to another embodiment of the present invention.

Fig. 6 is a schematic diagram of a circuit board assembly according to yet another embodiment of the present invention.

Fig. 7 is a schematic diagram of a server according to an embodiment of the invention.

Fig. 8 is a schematic diagram of an architecture within a server according to an embodiment of the invention.

Reference numerals:

the prior art is as follows:

an intermediate plate 11 ', a dielectric layer 12', a heat conducting layer 13 ', a conductive layer 15', a solid copper pillar 16 ', a hollow copper pillar 17',

chip 20 ', bare wafer 21', contact bumps 22 ', substrate 23', thermal pad 24 ', LGA pins 25', molding compound 26 ', solder 27',

a heat sink 30';

the utility model discloses:

a circuit board assembly 100, a case 200, a blowing fan 300, an exhaust fan 400, a server 500,

a PCB (printed circuit board) 10, a main board body 11, a medium layer 12, a conductive layer 13, a heat conducting block 14, a heat conducting piece 15, a main heat conducting piece 15a, an auxiliary heat conducting piece 15b, a tin solder 16,

the number of chips 20 is such that,

and a heat sink 30.

Detailed Description

Embodiments of the present invention are described in detail below, and the embodiments described with reference to the drawings are exemplary.

A circuit board assembly 100 according to an embodiment of the present invention is described below with reference to fig. 4-8.

According to the utility model discloses circuit board assembly 100 of the first aspect embodiment includes: a PCB board 10, a plurality of chips 20, and a plurality of heat sinks 30.

As shown in fig. 4, the PCB board 10 includes: the heat conducting plate comprises a main plate body 11, a medium layer 12, a conducting layer 13 and a plurality of heat conducting blocks 14, wherein the main plate body 11 comprises a middle plate and heat conducting layers arranged on two sides of the middle plate. The dielectric layer 12 is made of insulating materials, and the dielectric layer 12 is distributed on one side of the main board body 11; the conducting layer 13 and the dielectric layer 12 are positioned on the same side of the main plate body 11, and the conducting layer 13 are bonded through the dielectric layer 12; the heat conduction block 14 is a solid structure, and the heat conduction block 14 is embedded in the PCB 10.

The chips 20, the conductive layer 13 and the medium layer 12 are positioned on the same side of the main board body 11, the chips 20 are fixed with the PCB 10 and electrically connected with the conductive layer 13, and each heat conduction block 14 penetrates through the conductive layer 13 to be in contact with the chip 20 positioned outside the conductive layer; the plurality of heat sinks 30 are connected to a side of the PCB board 10 away from the chip 20, and correspond to the plurality of heat-conducting blocks 14 one by one. The chip 20 and the circuit board, and the heat sink and the circuit board may be fixedly connected by soldering 16.

According to the utility model discloses circuit board assembly 100, through burying a plurality of heat conduction piece 14 that the components of a whole that can function independently set up underground in PCB board 10, every heat conduction piece 14 corresponds a chip 20 so that the heat of chip 20 directly transmits fin 30 through heat conduction piece 14, chip 20 below is whole by heat conduction piece 14 intercommunication to the back of PCB board 10 like this, the hot route of chip 20 bottom has been opened, make the heat can be better release to heat conduction piece 14 through chip 20 bottom, the holistic heat-sinking capability of subassembly has been promoted, the temperature of chip 20 has been reduced.

In order to enhance the practical application of heat transfer of the circuit board, the heat dissipation of the heat sink can be mounted on the upper portion of the chip 20 by improving the heat conductivity coefficient of the circuit board, and the heat sink can be welded on the back of the PCB at the same time, so that the heat dissipation of the chip 20 can be enhanced in an upper path and a lower path, and a better heat dissipation effect can be achieved.

In some embodiments, the width of the area corresponding to each chip 20 and the thermal conduction block 14 is 1/2 times-1 times the width of the chip 20. Thus, under the heat conducting plate of the chip 20, at least half of the area of the dielectric layer 12 opposite to the chip 20 is occupied by the heat conducting block 14 (the heat conducting block 14 can be a copper block or a copper column) in the width direction, so that the thermal conductivity of the dielectric layer 12 can be increased to 90-385W/(mK).

In some embodiments, the heat conduction blocks 14, the heat conduction layer, and the conductive layer 13 are made of copper, the plurality of heat conduction blocks 14 are disposed at intervals, and the plurality of heat conduction blocks 14 are soldered to the heat conduction pads of the plurality of chips 20. Thus, the heat transfer of the chip 20 to the heat conductive block 14 is accelerated by separately embedding copper and by soldering the heat conductive plate of the chip 20 to the heat conductive block 14.

Of course, the present invention is not limited thereto, and the heat conducting block 14 is not limited to copper, and may be made of other metal or alloy material with high heat conductivity.

In some embodiments, the thermal resistance of the PCB 10 is 0.4-0.5K/W, and the equivalent thermal conductivity of the PCB 10 in the thickness direction is 300-400W/(mK). Therefore, the heat conductivity coefficient of the PCB 10 in the thickness direction is greatly improved, and the heat exchange effect is obviously improved.

The circuit board assembly 100 according to the second aspect of the present invention includes: a PCB board 10, a plurality of chips 20, and a plurality of heat sinks 30.

As shown in fig. 5 and 6, the PCB board 10 includes: the main board body 11 comprises a middle board and heat conduction layers arranged on two sides of the middle board, wherein the heat conduction layers are grounding layers; the dielectric layer 12 is made of insulating materials, and the dielectric layer 12 is distributed on one side of the main board body 11; the conductive layer 13 and the dielectric layer 12 are located on the same side of the main board body 11, and the conductive layer 13 are bonded through the dielectric layer 12.

The heat conduction member 15 includes a main heat conduction member 15a and a plurality of sub heat conduction members 15b, the main heat conduction member 15a is a solid structure embedded in the main plate body 11, one end of the sub heat conduction member 15b is connected with the main heat conduction member 15a, and the other end of the sub heat conduction member 15b penetrates through at least the medium layer 12.

The plurality of chips 20 are located on the same side of the main board body 11 as the conductive layer 13 and the dielectric layer 12, the chips 20 are fixed to the PCB board 10 and electrically connected to the conductive layer 13, the main heat-conducting member 15a corresponds to the plurality of chips 20 located at the same supply voltage, and each of the sub heat-conducting members 15b is in contact with the conductive layer 13 or a corresponding one of the chips 20. The plurality of heat sinks 30 are connected to a side of the PCB board 10 away from the chip 20, and correspond to the plurality of heat-conducting blocks 14 one by one.

According to the utility model discloses circuit board assembly 100, chip 20 is divided into the multiunit, a plurality of chips 20 that are located same way supply voltage are divided a set of, through whole bury leading heat-transfer member 15a underground in PCB board 10, make the heat of a plurality of chips 20 of same set of transmit this leading heat-transfer member 15a through each vice heat-transfer member 15b of being connected with same leading heat-transfer member 15a, chip 20 below assembles leading heat-transfer member 15a and is linked together through this a way of vice heat-transfer member 15b with PCB board 10's back like this, the hot route of chip 20 bottom has been broken through, make the heat can be better release to leading heat-transfer member 15a through chip 20 bottom, the holistic heat-sinking capability of subassembly has been promoted, the temperature of chip 20 has been reduced. In addition, compared with the way of separately embedding the heat conducting member 15, the heat conducting coefficient of the integrally embedded heat conducting member 15 is higher, and the heat dissipation effect is better

When the heat conducting member 15 is made of copper, the heat dissipation effect similar to that of pure copper can be achieved by integrally embedding. The whole copper-embedded circuit has a use condition and cannot influence the transmission of circuit signals. The copper layers in the circuit board are all grounding layers, circuit signals are only transmitted in the heat conduction layer (can be copper sheets) on the surface of the PCB, and the whole copper embedding has no influence on the original circuit.

In some embodiments, as shown in fig. 5, the secondary thermal conduction members 15b are copper blocks, and one secondary thermal conduction member 15b corresponds to each chip 20. Therefore, the copper block penetrates through the dielectric layer 12 and the heat conduction layer, one end of the copper block is connected with the main heat conduction piece 15a, the other end of the copper block is in contact with the heat conduction plate of the chip 20, and the copper block is made of solid materials and large in size, so that the heat dissipation effect is good.

In the embodiment shown in fig. 6, the sub heat-conductive member 15b has a plurality of minute holes arranged perpendicularly to the main plate body 11. Therefore, the heat of the heat conduction layer below each chip 20 can be transferred to the main heat conduction member 15a by a plurality of branches by providing the micro holes in the sub heat conduction member 15b corresponding to each chip 20, and the heat dissipation effect is good.

Further, the diameter of the micropores is 4mil to 6mil, and the thickness of the dielectric layer 12 is 2mil to 5 mil. Wherein, mil is thousandth of an inch, from this, the radiating effect is better.

In some embodiments, the width of the area of the secondary thermal conduction member 15b corresponding to the chip 20 is 1/2-1 times the width of the chip 20. Thereby, the contact area of the sub heat-conducting member 15b with the chip 20 is sufficiently large, thereby facilitating the rapid heat dissipation from the chip 20.

In summary, the process flow of the method for separately burying copper and the method for integrally burying copper comprises the following steps: the inner layer pattern, the window for cutting and embedding the through hole, the laminated plate, the copper block placing, the pressing and the outer layer pattern are processed by embedding the copper block, so that the heat conduction Pad (namely a heat conduction plate) below the chip 20 is communicated with the back of the PCB 10 by the copper block, the heat conduction coefficient of the PCB 10 in the thickness direction reaches the level of pure copper, and a split radiator at the back is matched to open a heat path at the bottom of the chip 20, so that heat can be better released through the bottom, the whole heat dissipation capacity can be further improved, and the temperature of the chip 20 is reduced.

The utility model discloses circuit board assembly 100 has following advantage:

1) the copper-embedded scheme of the PCB 10 can be used in cooperation with a split radiator welded on the back of the PCB 10, so that the heat dissipation of the whole machine is further enhanced, and the whole heat dissipation capability is expected to reach the maximum;

2) directly burying a copper block (separately buried copper) in the PCB 10(FR4 board) right below the chip 20, wherein the thermal conductivity of the FR4 board can be increased to 385W/(mK) from 90W/(mK) of the HDI scheme;

3) the heat conductivity coefficient of the PCB can be increased to 385W/(mK) from 90W/(mK) of the HDI scheme by embedding copper strips in FR4 below the chip 20 group with the same power supply voltage, namely embedding copper integrally;

4) the copper block embedding process can be used in combination with the thermal via hole and copper pillar embedding process, such as embedding a copper block in the main board body 11, and punching a through hole or embedding a copper pillar in the dielectric layer 12;

5) the two modes of separately embedding copper and integrally embedding copper can be selected according to different conditions, and the scheme of PCB heating via holes such as HDI (high density interconnect) and the like is replaced by the scheme of PCB separately embedding copper blocks or integrally embedding copper blocks; the thermal conductivity of the PCB is improved;

6) the method for embedding the copper block is not limited to the copper material, and can also be expanded to other metals or alloy materials with high heat conductivity coefficient, thereby providing a new idea for further improving the heat conductivity coefficient of the PCB.

7) The heat conductivity coefficient of the common PCB 10 material is only 38.77-47.19W/(mK), the heat conductivity coefficient of the PCB 10 material can be increased by 7 times through the PCB embedded copper block, and the thermal resistance is reduced by 70%, as shown in Table 1;

TABLE 1 comparison of heat conductivity of PCB boards

PCB technology	4-layer through hole plate	HDI scheme	Split copper-buried plate	Integral copper-buried
					PCB thermal resistance K/W	1.86	1.26	0.47	0.47
PCB equivalent thermal conductivity Kz, W/(mK)	47.19	92.98	385	385
					PCB equivalent thermal conductivity Kxy, W/(mK)	38.77	38.77	38.77	38.77

The server 500 according to the third aspect of the present invention includes: the fan comprises a box body 200, a plurality of circuit board assemblies 100 of the above embodiments and a fan, wherein the circuit board assemblies 100 are arranged in the box body 200 and are sequentially arranged along the width direction of the box body 200; the fans are provided at both ends of the case 200 in the longitudinal direction, and the fan at one end is formed as an air supply fan 300 and the fan at the other end is formed as an air discharge fan 400.

Accordingly, the blowing fan 300 blows air into the case 200, the air flow is blown in parallel to each circuit board to take away heat of the chip 20 and the heat sink 30, and the exhaust fan 400 discharges the air flow with heat to the outside of the case 200, thereby achieving heat dissipation of the circuit board assembly 100.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", and the like, indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be construed as limiting the present invention.

In the description of the present invention, "the first feature" and "the second feature" may include one or more of the features. In the description of the present invention, "a plurality" means two or more. In the description of the present invention, the first feature "on" or "under" the second feature may include the first and second features being in direct contact, and may also include the first and second features being in contact with each other not directly but through another feature therebetween. In the description of the invention, the first feature being "on", "above" and "above" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example.

While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A circuit board assembly, comprising:

a PCB board, the PCB board including:

the heat conduction plate comprises a main plate body and a heat conduction layer, wherein the main plate body comprises a middle plate and heat conduction layers arranged on two sides of the middle plate;

the dielectric layer is made of insulating materials and is distributed on one side of the main board body;

the conducting layer and the dielectric layer are positioned on the same side of the main plate body, and the conducting layer are bonded through the dielectric layer;

the heat conduction blocks are of solid structures and are embedded in the PCB;

the chips, the conducting layer and the medium layer are positioned on the same side of the main board body, the chips are fixed with the PCB and electrically connected with the conducting layer, and each heat conducting block penetrates through the conducting layer to be in contact with the chip positioned on the outer side of the conducting layer;

the radiating fins are connected to one side of the PCB, which is far away from the chip, and correspond to the heat conducting blocks one to one.

2. The circuit board assembly of claim 1, wherein the width of the area corresponding to each chip and the heat-conducting block is 1/2-1 times the width of the chip.

3. The circuit board assembly of claim 1, wherein the heat-conducting blocks, the heat-conducting layer and the conductive layer are made of copper, a plurality of the heat-conducting blocks are spaced apart from each other, and a plurality of the heat-conducting blocks are soldered to the heat-conducting pads of a plurality of chips.

4. The circuit board assembly as claimed in claim 1, wherein the thermal resistance of the PCB is 0.4-0.5K/W, and the equivalent thermal conductivity of the PCB in the thickness direction is 300-400W/(mK).

5. A circuit board assembly, comprising:

a PCB board, the PCB board including:

the main board body comprises a middle board and heat conduction layers arranged on two sides of the middle board, and the heat conduction layers are grounding layers;

the heat conducting piece comprises a main heat conducting piece and a plurality of auxiliary heat conducting pieces, the main heat conducting piece is of a solid structure embedded in the main board body, one end of each auxiliary heat conducting piece is connected with the main heat conducting piece, and the other end of each auxiliary heat conducting piece at least penetrates through the medium layer;

the plurality of chips, the conducting layer and the dielectric layer are positioned on the same side of the main board body, the chips are fixed with the PCB and are electrically connected with the conducting layer, the main heat conducting piece corresponds to the plurality of chips positioned at the same power supply voltage, and each auxiliary heat conducting piece is in contact with the conducting layer or one corresponding chip;

6. The circuit board assembly of claim 5, wherein the secondary thermal conductive members are copper blocks, and each chip corresponds to one of the secondary thermal conductive members.

7. The circuit board assembly of claim 6, wherein the secondary thermal conductor member has a plurality of micro-holes disposed perpendicular to the main board body.

8. The circuit board assembly of claim 7, wherein the micro-vias have a diameter of 4-6 mils and the dielectric layer has a thickness of 2-5 mils.

9. The circuit board assembly of claim 6, wherein the area of the secondary thermal conductive member corresponding to the chip has a width 1/2-1 times the width of the chip.

10. A server, comprising:

a box body;

a plurality of circuit board assemblies according to any one of claims 1 to 9, the plurality of circuit board assemblies being disposed in the case and arranged in sequence along a width direction of the case;

and the fans are arranged at two ends of the box body in the length direction, the fan at one end is formed into an air supply fan, and the fan at the other end is formed into an air exhaust fan.