Heat dissipation structure and chip assembly

Abstract

The utility model is suitable for the technical field of chip heat dissipation, and discloses a heat dissipation structure and a chip assembly.The heat dissipation structure comprises a radiator and a heat conduction main body, the radiator and a circuit board are connected through a detachable elastic connecting assembly, and the heat conduction main body is arranged on the radiator and located between the radiator and a chip; a first surface and a second surface are arranged on the side, away from the radiator, of the heat conduction body and are arranged in the first direction, a first gap is formed between the first surface and the first area in the first direction, a second gap is formed between the second surface and the second area in the first direction, and the interval of the first gap is smaller than that of the second gap; the first gap and the second gap are both filled with thermal interface materials, the thermal conductivity coefficient of the thermal interface material located in the first gap is k1, the thermal conductivity coefficient of the thermal interface material located in the second gap is k2, and k1 and k2 meet the condition that k1 is larger than or equal to k2. The heat dissipation structure of the embodiment can reduce the force on the circuit board and reduce the deformation of the circuit board.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chip heat dissipation, and in particular to a heat dissipation structure and a chip assembly. BACKGROUND

[0002] A chip includes a package substrate and a core part (die) formed on the package substrate, and the main component of the core part is silicon. When designing the heat dissipation of the chip, if the core part of the chip is directly contacted with a heat sink, the core part of the chip will be easily broken. Therefore, when packaging the chip, a metal shell with good heat conduction performance is arranged to cover the package substrate and the core part.

[0003] In the related art, when a heat sink is arranged for a chip mounted on a circuit board, a heat-conductive material is filled in a structural gap between the metal shell of the chip and the heat sink, and only when the heat-conductive material is compressed to a certain thickness can an ideal heat conduction effect be achieved. The other side of the chip is welded to the circuit board through solder balls to realize the transmission of power supply and signals. However, if the interaction force between the heat sink and the chip is too large, the force received by the circuit board will be increased, causing the circuit board to be deformed greatly, resulting in that the local solder balls are severely deformed and even broken, which affects the transmission of power supply and signals. CONTENT OF THE INVENTION

[0004] The first object of the present application is to provide a heat dissipation structure which aims to solve the technical problem that the interaction force between the heat sink and the chip on the circuit board is too large, which easily causes the circuit board to be deformed greatly.

[0005] To achieve the above object, the present application provides the following scheme:

[0006] A heat dissipation structure for dissipating heat for a chip mounted on a circuit board, the chip has a first area and a second area formed on a side away from the circuit board, the distance between the first area and a heat source of the chip is smaller than the distance between the second area and the heat source of the chip, the heat generation of the first area is greater than the heat generation of the second area, and the heat dissipation structure comprises:

[0007] a heat sink, the heat sink is connected with the circuit board through a detachable elastic connecting assembly;

[0008] a heat-conducting main body, the heat-conducting main body is arranged on the heat sink and located between the heat sink and the chip;

[0009] a first surface and a second surface are arranged on a side of the heat-conducting main body away from the heat sink, and the first surface and the second surface are arranged along a first direction;

[0010] In the first direction, a first gap is formed between the first surface and the first region, and a second gap is formed between the second surface and the second region, the first gap has a smaller interval than the second gap, and the first direction is the arrangement direction of the heat sink and the circuit board.

[0011] The first gap and the second gap are both filled with thermal interface materials to form a first thermal conductive layer and a second thermal conductive layer respectively, the thermal conductive coefficient of the thermal interface material in the first gap is k1, the thermal conductive coefficient of the thermal interface material in the second gap is k2, and k1 and k2 satisfy k1≥k2.

[0012] A second object of the present application is to provide a chip assembly comprising a circuit board, a chip, and the heat dissipation structure described above, the chip comprises a packaging substrate, a heat-generating silicon wafer, and a metal shell, the packaging substrate is mounted on the circuit board, the heat-generating silicon wafer is formed on the packaging substrate, and the metal shell is arranged on the packaging substrate and covers the packaging substrate and the heat-generating silicon wafer; the first region and the second region are formed on the side of the metal shell facing the heat dissipation structure, and the first region covers the heat-generating silicon wafer.

[0013] The heat dissipation structure provided by the present application has the following beneficial effects:

[0014] In the embodiment, the elastic connecting assembly is used to connect the heat sink and the circuit board, and after the heat sink, the chip, and the circuit board are assembled, the elastic connecting assembly acts on the heat sink and the circuit board respectively, and then under the compression of the heat conductive main body and the chip, the thermal interface material in the first gap forms a first thermal conductive layer, and the thermal interface material in the second gap forms a second thermal conductive layer. Moreover, the interval of the first gap in the first direction is smaller than the interval of the second gap in the first direction, so that the thickness of the first thermal conductive layer is smaller than the thickness of the second thermal conductive layer. On this basis, the thermal interface material with a higher thermal conductive coefficient or the same thermal conductive coefficient can make the thermal conductive effect of the first thermal conductive layer higher than that of the second thermal conductive layer.

[0015] Moreover, compared with the way of covering the entire surface area of the chip with the thermal interface material having a high thermal conductive coefficient, the above arrangement of the present embodiment can reduce the contact area of the thermal interface material and the surface of the chip, so that in the case of compressing the thermal interface material in the first region to the same thickness, the elastic connecting assembly exerts a smaller force on the heat sink and the circuit board when compressing the thermal interface material, thereby reducing the force on the circuit board and the deformation amount of the circuit board, avoiding the circuit board from being pressed to damage the solder balls on the chip connected with the circuit board, and improving the reliability of the chip. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from the structures shown in these drawings without creative labor.

[0017] Figure 1 is a structural schematic diagram of a chip assembly provided by an embodiment of the present application;

[0018] Figure 2 is Figure 1 is a partial enlarged schematic diagram at i in

[0019] Figure 3 is a structural schematic diagram of a heat dissipation structure provided by an embodiment of the present application;

[0020] Figure 4 is a structural schematic diagram of a heat conduction main body provided by an embodiment of the present application;

[0021] Figure 5 is a structural schematic diagram of an assembly structure of a chip and a circuit board provided by an embodiment of the present application.

[0022] Figure 6 is another structural schematic diagram of a chip assembly provided by an embodiment of the present application;

[0023] Figure 7 is Figure 6 is a partial enlarged schematic diagram at ii in

[0024] Figure 8 is another structural schematic diagram of a heat dissipation structure provided by an embodiment of the present application;

[0025] Figure 9 is another structural schematic diagram of a heat conduction main body provided by an embodiment of the present application.

[0026] Explanation of reference signs:

[0027] 100, chip assembly; 10, heat dissipation structure;

[0028] 1, heat sink; 11, heat dissipation base plate; 12, heat dissipation fin; 2, heat conduction main body; 2a, first surface; 2b, second surface; 21, heat conduction platform; 21a, peripheral area; 22, heat conduction boss; 3, elastic connection assembly; 31, fixing piece; 32, elastic piece; 4, first heat conduction layer; 5, second heat conduction layer;

[0029] 20, circuit board; 201, second through hole; 30, chip; 301, solder ball; 302, package substrate; 303, heat generating silicon wafer; 304, metal shell; 40, bracket. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0031] It should be noted that all directional indications, such as up, down, left, right, front, back, etc., in the embodiments of the present application are only used to explain the relative position relationship, movement condition, etc. between components in a certain posture, and if the certain posture changes, the directional indications also change accordingly.

[0032] It should also be noted that when an element is referred to as being "fixed" or "set" on another element, it can be directly on the other element or can have a middle element. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or can be indirectly connected to the other element through a middle element.

[0033] In addition, the description involving "first", "second" and the like in the present application is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions of various embodiments can be combined with each other, but it must be based on the realization of a person skilled in the art, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, nor within the scope of protection claimed by the present application.

[0034] First group of embodiments:

[0035] The heat dissipation structure 10 provided in the embodiment can refer to Figures 1 to 5 .

[0036] As Figure 1 and Figure 2As shown, the heat dissipation structure 10 provided by the embodiment of the present application can dissipate heat of the chip 30 on the circuit board 20, and the circuit board 20 can be a circuit board 20 of other supercomputing equipment, which is not specifically limited in the embodiment. Wherein, the side of the chip 30 away from the circuit board 20 forms a first area (not shown in the figure) and a second area (not shown in the figure), the distance between the first area and the heat source of the chip 30 is less than the distance between the second area and the heat source of the chip 30, that is, the first area is close to the heat source of the chip 30, and the second area is away from the heat source of the chip 30, so that the heat generation of the first area is greater than that of the second area.

[0037] Specifically, the heat dissipation structure 10 of the embodiment includes a heat sink 1 and a heat-conducting body 2, the heat sink 1 is connected with the circuit board 20 through a detachable elastic connecting assembly 3, the heat-conducting body 2 is arranged on the heat sink 1 and located between the heat sink 1 and the chip 30, used for transferring heat of the chip 30 to the heat sink 1, and the heat sink 1 is used for heat dissipation; the side of the heat-conducting body 2 away from the heat sink 1 has a first surface 2a and a second surface 2b, the first surface 2a and the second surface 2b are arranged along a first direction, and the first direction is the arrangement direction of the heat sink 1 and the circuit board 20; along the first direction, the first surface 2a and the first area form a first gap (not shown in the figure), and the second surface 2b and the second area form a second gap (not shown in the figure), and the interval of the first gap is less than the interval of the second gap; the first gap and the second gap are both filled with thermal interface materials to form a first heat-conducting layer 4 and a second heat-conducting layer 5 respectively, so as to transfer heat of the chip 30 to the first surface 2a and the second surface 2b respectively, the thermal conductivity coefficient of the thermal interface material located in the first gap is k1, the thermal conductivity coefficient of the thermal interface material located in the second gap is k2, and k1 and k2 satisfy k1≥k2.

[0038] In the embodiment, the heat sink 1 is connected with the circuit board 20 through the elastic connecting assembly 3, and after the heat sink 1, the chip 30 and the circuit board 20 are assembled, the first surface 2a of the heat-conducting body 2 and the first area of the chip 30 form a first gap, and the second surface 2b of the heat-conducting body 2 and the second area of the chip 30 form a second gap, so that when the thermal interface materials are filled in the first gap and the second gap respectively, the elastic connecting assembly 3 can act on the heat sink 1 and the circuit board 20 respectively, and then under the compression of the heat-conducting body 2 and the chip 30, the thermal interface material in the first gap forms the first heat-conducting layer 4, and the thermal interface material in the second gap forms the second heat-conducting layer 5, and moreover, the interval of the first gap along the first direction is less than the interval of the second gap along the first direction, so that the thickness of the first heat-conducting layer 4 is less than the thickness of the second heat-conducting layer 5.

[0039] It can be known that the heat generation of the first region of the chip 30 is much greater than that of the second region, and compared with the second heat conduction layer 5, the first heat conduction layer 4 is closer to the heat source of the chip 30, so the thickness of the first heat conduction layer 4 is thinner, and on this basis, the thermal interface material with higher or same thermal conductivity is selected, for example, the same thermal interface material is filled in the first gap and the second gap, in which case k1=k2; for another example, different thermal interface materials are filled in the first gap and the second gap, and k1>k2, and the above can realize that the heat conduction effect of the first heat conduction layer 4 is higher than that of the second heat conduction layer 5.

[0040] Moreover, compared with the way of covering the entire surface area of the chip 30 with the thermal interface material with high thermal conductivity, the above setting of the embodiment can reduce the contact area of the thermal interface material with the surface of the chip 30, so that in the case of compressing the thermal interface material located in the first region to the same thickness (i.e. in the case of keeping the contact pressure of the thermal interface material located in the first region with the chip 30 unchanged), the elastic connecting assembly 3 exerts smaller force on the heat sink 1 and the circuit board 20 respectively (i.e. the force of the elastic connecting assembly 3 locking the heat sink 1 and the circuit board 20) when compressing the thermal interface material, thereby reducing the force on the circuit board 20 and the deformation amount of the circuit board 20, avoiding the circuit board 20 crushing the solder balls 301 connected with the circuit board 20 on the chip 30, such as avoiding the phenomenon of serious deformation or even fragmentation of the solder balls 301 on the chip 30, effectively reducing the risk of failure of the chip 30 and improving the reliability of the chip 30.

[0041] In addition, compared with the first heat conduction layer 4, the second heat conduction layer 5 is farther away from the heat source, and the thickness of the second heat conduction layer 5 is greater, so that the thermal interface material in the second gap requires smaller pressure when being compressed, and the elastic connecting assembly 3 can also exert smaller force on the heat sink 1 and the circuit board 20 respectively, thereby reducing the force on the circuit board 20 and the deformation amount of the circuit board 20.

[0042] As shown in Figure 1 and Figure 3 It can be known that the first region is the central region of the chip 30, the heat source of the chip 30 is located in the first region, the second region surrounds the outer periphery of the first region, and the heat conduction body 2 is arranged opposite to the chip 30 along the first direction, so as an implementation form, the second surface 2b is arranged around the outer periphery of the first surface 2a.

[0043] As shown in Figure 1 , Figure 3 and Figure 4As shown, as an embodiment, the heat-conducting body 2 comprises a heat-conducting platform 21 and a heat-conducting boss 22, the heat-conducting platform 21 is arranged on the heat sink 1, one side of the heat-conducting platform 21 away from the heat sink 1 forms a middle area (not shown in the figure) and a peripheral area 21a arranged around the outer periphery of the middle area, the heat-conducting boss 22 is connected in layers on the middle area, which helps to transfer the heat of the chip 30 to the heat-conducting platform 21, one side of the heat-conducting boss 22 away from the heat-conducting platform 21 forms a first surface 2a, and one side of the peripheral area 21a away from the heat sink 1 forms a second surface 2b.

[0044] As shown in Figure 1 and Figure 3 As an embodiment, in the first direction, the ratio between the projected area of the heat-conducting boss 22 and the projected area of the heat-conducting platform 21 is s, and s is less than 1, so as to reduce the contact area of the thermal interface material formed on the heat-conducting boss 22 with the chip 30, thereby reducing the force of the elastic connecting assembly 3 locking the heat sink 1 and the circuit board 20, and further reducing the stress of the circuit board 20.

[0045] In a specific embodiment, s satisfies: 0.6≤s≤0.7. In this embodiment, the area of the heat-conducting boss 22 occupies 60%~70% of the surface area of the heat-conducting platform 21, which can greatly reduce the contact area of the thermal interface material formed on the heat-conducting boss 22 with the chip 30, thereby reducing the force of the elastic connecting assembly 3 locking the heat sink 1 and the circuit board 20, and further reducing the stress of the circuit board 20. For example, the heat-conducting boss 22 and the heat-conducting platform 21 can both be made of metal materials, such as copper or aluminum, to achieve heat transfer. In a specific embodiment, the heat-conducting platform 21 is welded on the heat sink 1, and the heat-conducting boss 22 is integrally connected to the heat-conducting platform 21.

[0046] As shown in Figure 3 and Figure 4 As an embodiment, the first surface 2a and the second surface 2b are arranged in parallel and staggered along the first direction, the first surface 2a and the second surface 2b are connected by the side surface of the heat-conducting boss 22, and the side surface of the heat-conducting boss 22 is arranged at an angle with the second surface 2b, such as a 90-degree included angle, that is, the edge of the heat-conducting boss 22 is arranged as a right angle, so as to effectively ensure that the first gap along the first direction has a smaller spacing than the second gap along the first direction.

[0047] As shown in Figure 1 and Figure 3As shown in FIG. 1, as an embodiment, the heat sink 1 includes a heat dissipation base plate 11 and a plurality of heat dissipation fins 12, the heat conductive body 2 is arranged on the heat dissipation base plate 11, specifically, the heat conductive platform 21 is arranged on the side of the heat dissipation base plate 11 facing the chip 30 to transfer heat to the heat dissipation base plate 11, and the plurality of heat dissipation fins 12 are arranged on the side of the heat dissipation base plate 11 away from the chip 30 for heat dissipation, and the heat dissipation base plate 11 is connected with the circuit board 20 through the elastic connecting assembly 3.

[0048] As shown in FIG. 1, as an embodiment, the heat sink 1 includes a heat dissipation base plate 11 and a plurality of heat dissipation fins 12, the heat conductive body 2 is arranged on the heat dissipation base plate 11, specifically, the heat conductive platform 21 is arranged on the side of the heat dissipation base plate 11 facing the chip 30 to transfer heat to the heat dissipation base plate 11, and the plurality of heat dissipation fins 12 are arranged on the side of the heat dissipation base plate 11 away from the chip 30 for heat dissipation, and the heat dissipation base plate 11 is connected with the circuit board 20 through the elastic connecting assembly 3. Figure 1 、 Figure 2 and Figure 3 As shown in FIG. 1, as an embodiment, the number of the elastic connecting assembly 3 is multiple, and the multiple elastic connecting assemblies 3 are distributed around the position where the heat conductive platform 21 is arranged to jointly act on the heat sink 1 and the circuit board 20, so that the thermal interface material between the heat sink 1 and the chip 30 is compressed. In a specific application, the number of the elastic connecting assembly 3 is four, and the four elastic connecting assemblies 3 are distributed around the heat conductive platform 21, and the heat conductive platform 21 is directly opposite to the chip 30, so that the four elastic connecting assemblies 3 are distributed around the chip 21, and when the thermal interface material is compressed, the pressure can be dispersed to the metal shell 304 of the chip 30.

[0049] As shown in FIG. 1, as an embodiment, the heat sink 1 is provided with a plurality of first through holes (not shown in the figure), the circuit board 20 is provided with a plurality of second through holes 201, the plurality of first through holes, the plurality of second through holes 201 and the plurality of elastic connecting assemblies 3 correspond one by one; each elastic connecting assembly 3 includes a fixing member 31 and an elastic member 32, the fixing member 31 respectively passes through the first through hole and the second through hole 201 to fixedly connect the heat sink 1 and the circuit board 20; the elastic member 32 is arranged around the fixing member 31, one end of the elastic member 32 is abutted against the end of the fixing member 31 away from the circuit board 20 along the first direction, and the other end of the elastic member 32 is abutted against the heat sink 1 to provide the pressure required for the heat sink 1 and the chip 30 to compress the thermal interface material. Exemplarily, the fixing member 31 is a screw, and the elastic member 32 is a spring. Figure 1 Figure 5 As shown in FIG. 1, as an embodiment, the thermal interface material includes at least one of heat conductive silicone grease (also known as heat conductive paste) and heat conductive silicone rubber pad. In a specific embodiment, the first gap and the second gap are both filled with heat conductive silicone grease or heat conductive silicone rubber pad. In another specific embodiment, the thermal interface material with high thermal conductivity is used in the area close to the heat source, and the thermal interface material with low thermal conductivity is used in the area away from the heat source, for example, the first gap is filled with heat conductive silicone grease, and the second gap is filled with heat conductive silicone rubber pad.

[0050] As shown in FIG. 1, as an embodiment, the thermal interface material includes at least one of heat conductive silicone grease (also known as heat conductive paste) and heat conductive silicone rubber pad. In a specific embodiment, the first gap and the second gap are both filled with heat conductive silicone grease or heat conductive silicone rubber pad. In another specific embodiment, the thermal interface material with high thermal conductivity is used in the area close to the heat source, and the thermal interface material with low thermal conductivity is used in the area away from the heat source, for example, the first gap is filled with heat conductive silicone grease, and the second gap is filled with heat conductive silicone rubber pad. Figure 1 As shown in FIG. 1, as an embodiment, the thermal interface material includes at least one of heat conductive silicone grease (also known as heat conductive paste) and heat conductive silicone rubber pad. In a specific embodiment, the first gap and the second gap are both filled with heat conductive silicone grease or heat conductive silicone rubber pad. In another specific embodiment, the thermal interface material with high thermal conductivity is used in the area close to the heat source, and the thermal interface material with low thermal conductivity is used in the area away from the heat source, for example, the first gap is filled with heat conductive silicone grease, and the second gap is filled with heat conductive silicone rubber pad.

[0051] Figure 2 ​​It is known that thermal grease has a high thermal conductivity, and the thinner the thermal grease, the better the thermal conductivity. However, if it is too thin, it is difficult for the thermal grease to form a sheet, affecting the thermal conductivity. Therefore, in a specific embodiment, the thermal interface material in the first gap is thermal grease, and the thickness of the first thermally conductive layer 4 along the first direction is 0.05mm to 0.15mm to have good thermal conductivity. Preferably, the thickness of the first thermally conductive layer 4 along the first direction is about 0.1mm, which provides good thermal conductivity.

[0052] Combination Figure 2 As we know, thermally conductive silicone pads are sheet-like materials. The thinner the pad, the better the thermal conductivity. However, if the pad is too thin, it is easy for it to crack, which will affect the thermal conductivity. In addition, the thermal conductivity of thermally conductive silicone pads is weaker than that of thermally conductive grease. At the same time, the heat generation in the second region is lower than that in the first region. Therefore, in a specific embodiment, the thermal interface material in the second gap is a thermally conductive silicone pad, and the thickness of the second thermally conductive layer 5 along the first direction is 0.3mm to 6mm.

[0053] like Figure 1 and Figure 2 As shown, in some application scenarios, the bottom of the circuit board 20 is provided with a bracket 40. The bracket 40 and the heat sink 1 are arranged opposite to each other along the first direction. The bracket 40 is used to support the circuit board 20. The chip 30 includes a packaging substrate 302, a heat-generating silicon wafer 303 and a metal shell 304. The packaging substrate 302 is mounted on the circuit board 20. The heat-generating silicon wafer 303 is formed on the packaging substrate 302. The metal shell 304 is disposed on the packaging substrate 302 and covers the packaging substrate 302 and the heat-generating silicon wafer 303. The heat-generating silicon wafer 303 can be understood as the core part (die) of the chip 30. Its heat generation is higher than that of other parts of the chip 30 and can be used as a heat source for the chip 30. The first region and the second region are both formed on the metal shell 304. The first region covers the heat-generating silicon wafer 303.

[0054] In this scenario, because the first surface 2a of the heat-conducting body 2 is closer to the heat source than the second surface 2b of the heat-conducting body 2, the embodiment applies the heat-conducting silicone grease on the first surface 2a and pastes the heat-conducting silicone rubber pad on the second surface 2b, and makes the pressure of the heat sink 1 evenly distributed on the metal shell 304 to compress the thickness of the heat-conducting silicone grease to about 0.1 mm. Compared with the way of applying the heat-conducting silicone grease on the area of the heat sink 1 directly opposite to the metal shell 304 and compressing the thickness of the heat-conducting silicone grease on the entire upper surface of the metal shell 304 to about 0.1 mm, the embodiment can ensure that the contact pressure of the heat-conducting silicone grease near the heat source area on the metal shell 304 is constant, and can also reduce the area of the heat-conducting silicone grease contacting the metal shell 304, thereby reducing the pressure of compressing the heat-conducting silicone grease, specifically reducing the locking force of the spring required for compressing the heat-conducting silicone grease, and further reducing the stress of the circuit board 20 and the stress of the bracket 40. In this way, when the bracket 40 is arranged, the structure of the bracket 40 can be simplified, the thickness of the bracket 40 can be reduced, and thus the cost of the bracket 40 can be reduced. In addition, the bracket 40 can also reduce the space occupied by the bracket 40 on the bottom surface of the circuit board 20, thereby increasing the layout space on the upper surface of the circuit board 20, and further more components can be arranged on the upper surface of the circuit board 20 to meet the wider use requirements of the chip 30.

[0055] It can be known that the heat-conducting silicone rubber pad has basically no rebound force after being compressed to a preset thickness, so the compression amount required for the heat-conducting silicone rubber pad pasted on the second surface 2b is smaller than the compression amount required for the heat-conducting silicone grease applied on the first surface 2a, and even can be ignored, thereby the reaction force of the heat-conducting silicone rubber pad on the heat-conducting body 2 and the metal shell 304 can be ignored, that is, the interaction force between the heat-conducting silicone rubber pad and the heat sink 1 and the chip 30 is small, and thus the pressure of compressing the heat-conducting silicone grease can be reduced, and the stress of the circuit board 20 can be reduced.

[0056] It should be understood that in the above application scenario, the heat-conducting silicone grease can also be applied on the second surface 2b when the heat-conducting silicone grease is applied on the first surface 2a, and the pressure required for the heat-conducting silicone grease applied on the second surface 2b is smaller than the pressure required for the heat-conducting silicone grease applied on the first surface 2a, and also can reduce the pressure of compressing the heat-conducting silicone grease, thereby reducing the stress of the circuit board 20.

[0057] In combination with Figures 1 to 4 , the following will be described in more detail in combination with a specific application embodiment. Taking the chip 30 as an example, the surface area of the chip 30 is 65x65 mm, the surface area of the heat-generating silicon wafer 303 is 25.6x29.1 mm, the area of the central region of the chip 30 is 53x53 mm, the heat-generating silicon wafer 303 is located in the central region of the chip 30, and the ratio between the area of the heat-generating silicon wafer 303 and the area of the chip 30 is 17.6%.

[0058] For the chip 30, if the thermal grease is directly applied to the area of the heat sink 1 opposite to the metal shell 304, and the pressure of the thermal grease contacting the metal shell 304 is set to 10 PSI, so that the thickness of the thermal grease is compressed to about 0.1 mm, at this time, nearly 300N pressure is required to make the chip 30 and the heat sink 1 reach a pressure of 10 PSI, wherein 1 PSI is about 6895 Pa. It can be known that the temperature of the metal shell 304 is higher near the position of the heat-generating silicon wafer 303, so in the embodiment, the first area is formed at the middle position of the metal shell 304, and the second area surrounds the outer periphery of the first area, and the first area can be understood as the central area of the chip 30. In addition, the heat-conducting platform 21 is provided with a heat-conducting boss 22 opposite to the first area, and the thermal grease is applied on the heat-conducting boss 22, and the thermal silicone rubber pad is adhered to the peripheral area 21a of the heat-conducting platform 21. At the same time, the pressure of the thermal grease applied on the heat-conducting boss 22 contacting the metal shell 304 is set to 10 PSI, so that the thickness of the thermal grease is compressed to about 0.1 mm, at this time, the required spring pressure is reduced from 300N to 200N. It can be seen that the heat dissipation structure 10 of the embodiment can reduce the pressure required for compressing the thermal interface material, thereby reducing the stress of the circuit board 20.

[0059] Second group of embodiments:

[0060] Please refer to Figures 6 to 9 , the heat dissipation structure 10 provided by the embodiment is mainly different from the first embodiment in the structure of the heat-conducting main body 2:

[0061] As shown in Figure 6 and Figure 7 , as an implementation manner, the second surface 2b is arranged around the outer periphery of the first surface 2a, the first surface 2a is connected with the second surface 2b at an angle, the spacing of the second gap gradually increases along the second direction, the second direction is perpendicular to the first direction, and the second direction can be understood as the direction away from the first surface 2a. In the embodiment, the second surface 2b is inclined away from the chip 30, which can make the thickness of the thermal interface material filled in the second gap gradually increase along the second direction, and the force required for compressing the thermal interface material can gradually decrease, which is helpful to reduce the stress of the circuit board 20.

[0062] As shown in Figure 6 , Figure 8 and Figure 9 , as an implementation manner, the heat-conducting main body 2 includes a heat-conducting platform 21 and a heat-conducting boss 22, the heat-conducting platform 21 is arranged on the heat sink 1, and the heat-conducting boss 22 is connected in layers on the heat-conducting platform 21; the side of the heat-conducting boss 22 away from the heat-conducting platform 21 is the first surface 2a, and the side of the heat-conducting boss 22 is the second surface 2b.

[0063] In the embodiment, the side surface of the heat-conducting boss 22 is inclined, and the inclined surface is inclined towards the direction close to the heat sink 1, so that the thickness of the thermal interface material filled in the second gap gradually increases along the second direction, and the force required to compress the thermal interface material can gradually decrease, which helps to reduce the stress on the circuit board 20.

[0064] As shown in Figure 7 , in a specific embodiment, the first gap and the second gap are both filled with heat-conducting silicone grease, so that the first heat-conducting layer 4 and the second heat-conducting layer 5 formed are connected.

[0065] As shown in Figure 1 and Figure 2 , and in combination with Figure 6 and Figure 7 , the present application also provides a chip assembly 100 which can be applied to a supercomputer device. Specifically, the chip assembly 100 includes a circuit board 20, a chip 30, and the heat dissipation structure 10 of the first embodiment or the second embodiment. The chip 30 includes a packaging substrate 302, a heat-generating silicon wafer 303, and a metal shell 304. The packaging substrate 302 is mounted on the circuit board 20. The heat-generating silicon wafer 303 is formed on the packaging substrate 302. The heat-generating silicon wafer 303 can be understood as the core part (die) of the chip 30, which serves as the heat source of the chip 30. The metal shell 304 is arranged on the packaging substrate 302 and covers the packaging substrate 302 and the heat-generating silicon wafer 303. The first region and the second region are formed on the side of the metal shell 304 facing the heat dissipation structure 10, and the first region covers the heat-generating silicon wafer 303.

[0066] The chip assembly 100 in the embodiment can dissipate heat from the chip 30 on the circuit board 20 by using the heat dissipation structure 10 described above. Moreover, when compressing the thermal interface material between the heat sink 1 and the chip 30, the pressure required to compress the thermal interface material can be reduced, thereby reducing the stress on the circuit board 20, reducing the deformation amount of the circuit board 20, avoiding the circuit board 20 from crushing the solder balls 301 on the chip 30 which are in contact with the circuit board 20, effectively reducing the risk of failure of the chip 30, and improving the reliability of the chip assembly 100.

[0067] As shown in Figure 6 and Figure 7As shown, in a specific embodiment, the chip assembly 100 further comprises a bracket 40 arranged on the side of the circuit board 20 away from the chip 30, and the bracket 40 is used to support the circuit board 20. In this embodiment, the chip assembly 100 adopts the heat dissipation structure 10 described above, so that the stress on the circuit board 20 can be reduced, and the stress on the bracket 40 can be reduced, and then when the bracket 40 is arranged, the structure of the bracket 40 can be simplified, the thickness of the bracket 40 can be reduced, the cost of the bracket 40 can be reduced, and the space occupied by the bracket 40 on the bottom surface of the circuit board 20 can be reduced, so that the layout space on the top surface of the circuit board 20 can be increased, and then more components can be arranged on the top surface of the circuit board 20, so that the chip 30 can be used more widely.

[0068] The above merely describes the preferred embodiments of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation, direct / indirect application in other related technical fields, or the like, which is made based on the application concept of the present application and the content of the specification and drawings, is included in the patent protection scope of the present application.

Claims

1. A heat dissipation structure for dissipating heat from a chip mounted on a circuit board, wherein the side of the chip facing away from the circuit board forms a first region and a second region, the distance between the first region and the heat source of the chip is less than the distance between the second region and the heat source of the chip, and the heat generated in the first region is greater than the heat generated in the second region, characterized in that, The heat dissipation structure includes: A heat sink, wherein the heat sink is connected to the circuit board by a detachable elastic connection component; A heat-conducting body is disposed on the heat sink and located between the heat sink and the chip; The heat-conducting body has a first surface and a second surface on the side away from the heat sink, and the first surface and the second surface are arranged along a first direction; Along the first direction, a first gap is formed between the first surface and the first region, and a second gap is formed between the second surface and the second region, wherein the spacing of the first gap is smaller than the spacing of the second gap, and the first direction is the arrangement direction of the heat sink and the circuit board; Both the first gap and the second gap are filled with thermal interface material to form a first thermally conductive layer and a second thermally conductive layer, respectively. The thermal conductivity of the thermal interface material in the first gap is k1, and the thermal conductivity of the thermal interface material in the second gap is k2, and k1 and k2 satisfy k1≥k2.

2. The heat dissipation structure according to claim 1, characterized in that, The second surface is disposed around the outer periphery of the first surface.

3. The heat dissipation structure according to claim 2, characterized in that, The heat-conducting body includes a heat-conducting platform and a heat-conducting boss. The heat-conducting platform is disposed on the heat sink. The side of the heat-conducting platform facing away from the heat sink forms a middle area and a peripheral area. The peripheral area is arranged around the outer periphery of the middle area. The heat-conducting protrusions are stacked and connected on the middle region. The side of the heat-conducting protrusions facing away from the heat-conducting platform forms the first surface, and the side of the peripheral region facing away from the heat sink forms the second surface.

4. The heat dissipation structure according to claim 3, characterized in that, In the first direction, the ratio between the projected area of ​​the heat-conducting boss and the projected area of ​​the heat-conducting platform is s, and s satisfies: s < 1.

5. The heat dissipation structure according to claim 3, characterized in that, The first surface and the second surface are arranged parallel to and offset along the first direction. The first surface and the second surface are connected by the side of the heat-conducting boss. The side of the heat-conducting boss is set at an angle to the second surface.

6. The heat dissipation structure according to claim 2, characterized in that, The first surface and the second surface are connected at an angle, and the spacing of the second gap gradually increases along the second direction, which is perpendicular to the first direction; And / or, The heat-conducting body includes a heat-conducting platform and a heat-conducting boss. The heat-conducting platform is disposed on the heat sink, and the heat-conducting boss is stacked and connected to the heat-conducting platform. The side of the heat-conducting boss facing away from the heat-conducting platform is the first surface, and the side of the heat-conducting boss is the second surface.

7. The heat dissipation structure according to any one of claims 3-6, characterized in that, The number of elastic connection components is multiple, and the multiple elastic connection components are distributed around the location of the heat conduction platform.

8. The heat dissipation structure according to claim 7, characterized in that, The heat sink is provided with a plurality of first through holes, and the circuit board is provided with a plurality of second through holes. The plurality of first through holes and the plurality of second through holes correspond one-to-one with the plurality of elastic connection components. Each of the resilient connection components includes a fixing member and a resilient member, the fixing member passing through the first through hole and the second through hole respectively to fix the heat sink and the circuit board; The elastic element is arranged around the fixing element. Along the first direction, one end of the elastic element abuts against the end of the fixing element away from the circuit board, and the other end of the elastic element abuts against the heat sink.

9. The heat dissipation structure according to any one of claims 1-6, characterized in that, The thermal interface material includes at least one of thermal grease and thermal pad.

10. A chip assembly, characterized in that, include: Circuit board; The heat dissipation structure according to any one of claims 1-9; The chip includes a packaging substrate, a heat-generating silicon wafer, and a metal casing. The packaging substrate is mounted on the circuit board, the heat-generating silicon wafer is formed on the packaging substrate, and the metal casing is disposed on the packaging substrate and covers the packaging substrate and the heat-generating silicon wafer. A first region and a second region are formed on the side of the metal casing facing the heat dissipation structure, and the first region covers the heat-generating silicon wafer.

Images