Chip with heat dissipation structure and preparation process

Abstract

The invention relates to the technical field of semiconductors, and discloses a chip with a heat dissipation structure and a preparation technology, the chip comprises a circuit board used for connecting components, one side, far away from the components, of the circuit board is connected with a radiator, and the radiator is connected with the circuit board in a welding mode. The heat conductivity coefficient of the circuit board is larger than that of a traditional PCB, the circuit board and the radiator form an integrated structure in a welding mode, a connecting gap between the radiator and the circuit board can be reduced or avoided, in addition, the uneven surface of the radiator can be filled with welding flux used for welding, and the heat dissipation efficiency of the radiator is improved. The circuit board and the radiator which are connected through welding are more stable, a gap generated between the circuit board and the radiator due to vibration is prevented, thermal resistance is reduced, and the radiating effect of components is improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and more specifically, to a chip with a heat dissipation structure and a preparation process thereof. Background Art

[0002] With the rapid development of science and technology, the power of various electronic devices is getting higher and higher, especially the power modules, which are getting smaller and smaller. Because the electronic components are arranged too closely, the heat of the equipment is relatively concentrated. If the heat cannot be effectively diffused outward in time, the electronic equipment will work at high temperature for a long time and cause various forms of failure, which greatly limits the scope of use, service life and performance stability of electronic equipment.

[0003] The most effective way to conduct heat generated by chip devices is to exchange heat with the outside world through the bottom of the pad, PCB circuit board, interface material, and heat sink in sequence. The thermal conductivity of traditional PCB circuit boards is 0.2-5W / (m·K), and the heat of chip devices is transferred to the heat sink through the PCB circuit board and the thermal interface material.

[0004] When the heat sink is magnified, it can be clearly seen that its surface is obviously uneven. When the PCB circuit board contacts the heat sink, there is a certain gap between the two contact surfaces. Since the air heat transfer performance is very poor, contact thermal resistance is generated. When a large amount of heat passes through the contact surface, a large temperature difference will be generated. At present, thermal interface materials are used to fill the contact surface to squeeze the air out of the contact surface, thereby reducing the contact thermal resistance. However, thermal interface materials such as thermal grease (thermal conductivity 1-8W / (m·K)) have limited thermal conductivity. Due to the influence of vibration between the power device and the housing, the gap between the contact surfaces changes slightly. The thermal grease will increase the thermal resistance as the gap changes.

[0005] For heat dissipation applications of high-power devices such as IGBT (insulated gate bipolar transistor), the heat flux density tends to develop towards high power and high integration. The module also generates a large amount of heat due to its high-frequency conduction and opening and closing. The weakness of IGBT power semiconductor modules is overheating, and thermal management issues become the key. The thermal conductivity of PCB circuit board materials and thermal interface materials have become the bottleneck of thermal management of power devices.

[0006] Therefore, it is necessary to propose a chip with a heat dissipation structure and a preparation process to at least partially solve the problems existing in the prior art. Summary of the invention

[0007] A series of simplified concepts are introduced in the Summary of the Invention, which will be further described in detail in the Detailed Description of the Invention. The Summary of the Invention does not mean to attempt to define the key features and essential technical features of the claimed technical solution, nor does it mean to attempt to determine the scope of protection of the claimed technical solution.

[0008] To at least partially solve the above problems, the present invention provides a chip with a heat dissipation structure, including: a circuit board for connecting components, a heat sink connected to a side of the circuit board away from the components, and the heat sink and the circuit board are connected by welding.

[0009] Preferably, the circuit board comprises: a circuit layer, an insulating layer and a metal layer which are interconnected, the components are connected to the circuit layer via a solder paste layer, and the metal layer is soldered to the heat sink.

[0010] Preferably, the metal layer is made of copper or aluminum, and the metal layer is welded to the heat sink via nano solder.

[0011] Preferably, the metal layer comprises: an aluminum layer, a copper or nickel plating layer is provided on a side of the aluminum layer away from the insulating layer, and the plating layer is soldered to the heat sink by solder.

[0012] Preferably, the radiator is provided with a heat dissipation channel, and the heat dissipation medium passing through the heat dissipation channel is gas or liquid.

[0013] Preferably, a welding groove is provided on one side of the heat sink for welding to the circuit board, the welding groove is divided into a plurality of unit grooves by a supporting portion, the top surface of the supporting portion is at a first set distance from the top surface of the heat sink; solder for welding the circuit board and the heat sink is arranged in the unit groove.

[0014] Preferably, the edge of the circuit board is horizontally spaced apart from the edge of the welding groove by a second set distance, and a limit block for limiting the position of the circuit board is provided in the welding groove.

[0015] Preferably, the support portion includes: at least two cross-arranged support ribs, all of which form an intersection, and the intersection coincides with the vertical center line of the welding groove; each of the unit grooves has at least one point on the circumscribed circle of the bottom surface of the welding groove, and this point is a set point, and the bottom surface of each unit groove is inclined downward along the set point toward the intersection.

[0016] A process for preparing a chip with a heat dissipation structure, comprising: A welding groove is formed on one side of the heat sink, wherein the welding groove is divided into a plurality of unit grooves by a support portion, and the plurality of unit grooves form a bottom surface of the welding groove which is low in the middle and high at the edges; Arrange solder in each unit groove, and then position the circuit board in the solder groove; The solder is heated, and the circuit board is moved toward the heat sink so that the circuit board is at a third set distance from the support portion.

[0017] Preferably, the conditions for arranging solder in each unit groove are: the top surface of the arranged solder is higher than the top surface of the support portion, and the highest point of the solder after heating treatment is not higher than the top surface of the soldering groove.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects: The chip with heat dissipation structure and the preparation process described in the present invention have a circuit board with a larger thermal conductivity than that of a traditional PCB circuit board, and the circuit board and the heat sink are welded to form an integrated structure, which can reduce or avoid the connection gap between the heat sink and the circuit board. In addition, the solder used for welding can also fill the uneven surface of the heat sink. The circuit board and heat sink connected by welding are more stable, which prevents the generation of a gap between the two due to vibration, reduces thermal resistance, and improves the heat dissipation effect of components.

[0019] The chip with heat dissipation structure and the preparation process described in the present invention, and other advantages, objectives and features of the present invention will be reflected in part through the following description, and in part will be understood by technicians in this field through research and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 It is a schematic diagram of the connection structure between the heat dissipation structure and the chip in the prior art; Figure 2 This is a schematic diagram of the structure of the chip with a heat dissipation structure according to the present invention using nano solder and air cooling for heat dissipation; Figure 3 This is a schematic diagram of the structure of the chip with a heat dissipation structure according to the present invention using nano solder and liquid cooling for heat dissipation; Figure 4 This is a schematic diagram of the structure of the chip with a heat dissipation structure according to the present invention using common solder and air cooling; Figure 5 This is a schematic diagram of the structure of the chip with a heat dissipation structure according to the present invention using common solder and liquid cooling for heat dissipation; Figure 6 It is a schematic diagram of the structure of the welding groove in the chip with the heat dissipation structure according to the present invention; Figure 7A schematic diagram of the positions of the intersection points and the set points in the welding grooves of the chip with the heat dissipation structure according to the present invention; Figure 8 It is a schematic diagram of a top view of the chip with a heat dissipation structure according to the present invention; Fig. 9 For Figure 8 Schematic diagram of the cross-sectional structure at AA in the middle; Fig.10 A schematic diagram of the position of a circuit board when solder with poor fluidity is used in the preparation process of a chip with a heat dissipation structure according to the present invention; Fig.11 This is a schematic diagram of the position of a circuit board when solder with good fluidity is used in the preparation process of the chip with a heat dissipation structure described in the present invention. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments so that those skilled in the art can implement the invention with reference to the description.

[0022] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0023] like Figure 1 As shown, in the prior art, the PCB circuit board includes a circuit layer 4, a PCB thermal insulation layer 12 and a PCB metal base 13, the component 1 is connected to the PCB circuit board through a solder paste layer 7, and the PCB circuit board is connected to the radiator 3 through an interface material 14. The interface material 14 is generally made of thermal conductive silicone grease. The disadvantage of this connection method is that gaps are easily generated on the contact surface between the radiator 3 and the PCB circuit board, thereby increasing the thermal resistance and affecting the heat dissipation effect of the component 1.

[0024] like Figure 2-Figure 5 As shown, the present invention provides a chip with a heat dissipation structure, including: a circuit board 2 for connecting components 1, a heat sink 3 is connected to the side of the circuit board 2 away from the components 1, and the heat sink 3 and the circuit board 2 are connected by welding.

[0025] The circuit board 2 includes single-layer, double-layer or multi-layer circuits, and the material of the circuit board 2 includes one or more of flame-resistant material FR4 (grade code of flame-resistant material), IMS (insulated metal substrate), ceramic board and glass substrate; the thermal conductivity of the circuit board 2 is 0.2-200W / (m·K).

[0026] In the present invention, the circuit board 2 and the heat sink 3 are connected by welding, and then the component 1 is electrically connected to the circuit board 2. The heat generated by the component 1 during operation is transferred to the heat sink 3 through the circuit board 2 and dissipated through the heat sink 3.

[0027] In the above technical solution, the thermal conductivity of the circuit board 2 is greater than that of the traditional PCB circuit board, and the circuit board 2 and the heat sink 3 form an integrated structure by welding, which can reduce or avoid the connection gap between the heat sink 3 and the circuit board 2. In addition, the solder used for welding can also fill the uneven surface of the heat sink 3. The circuit board 2 and heat sink 3 connected by welding are more stable, preventing the generation of gaps between the two due to vibration, reducing thermal resistance, and improving the heat dissipation effect of the component 1.

[0028] like Figure 2 As shown, in one embodiment, the circuit board 2 includes: a circuit layer 4, an insulating layer 5 and a metal layer 6 which are interconnected, the component 1 is connected to the circuit layer 4 through a solder paste layer 7, and the metal layer 6 is soldered to the heat sink 3.

[0029] The circuit board 2 is soldered to the heat sink 3 through the metal layer 6. The insulating layer 21 preferably has an IMS (insulated metal substrate) with a higher thermal conductivity. The circuit layer 4 is a PCB copper foil layer, which is a single-layer, double-layer or multi-layer circuit. The component 1 is soldered to the circuit board 2 through the solder paste layer 7.

[0030] Furthermore, two solutions are provided for the selection of the metal layer 6 and the solder: like Figure 2 and Figure 3 The first one is shown, where the metal layer 6 is made of copper or aluminum material, and the metal layer 6 is welded to the heat sink 3 via nano solder 8 .

[0031] The metal layer 6 is made of copper or aluminum to improve the heat dissipation effect of the circuit board 2, and at the same time can ensure the welding bonding ability with the heat sink 3. The nano solder 8 can use nano silver solder paste. The nano solder 8 is coated on the surface of the heat sink 3, and then the circuit board 2 is stacked on the nano solder 8 so that the metal layer 6 is in contact with the nano solder 8. The heat sink 3 and the circuit board 2 are bonded by sintering the nano solder 8.

[0032] like Figure 4 and Figure 5 The second type is shown, the metal layer 6 includes: an aluminum layer 9, a copper or nickel plating layer 10 is provided on the side of the aluminum layer 9 away from the insulating layer 5, and the plating layer 10 is welded to the heat sink 3 by solder.

[0033] Among them, the solder uses any common solder 11 that can weld the coating 10 and the heat sink 3 together, the aluminum layer 9 can improve the heat dissipation effect of the circuit board 2, and copper or nickel plating on its surface can increase the welding bonding ability with the heat sink 3; when welding, the heat sink 3, the pre-prepared solid common solder 11 and the circuit board 2 can be stacked in sequence, and the common solder 11 is melted by heating, and then the circuit board 2 and the heat sink 3 can be bonded after solidification.

[0034] like Figure 2-Figure 5 As shown, in one embodiment, a heat dissipation channel 31 is provided on the radiator 3, and the heat dissipation medium passing through the heat dissipation channel 31 is gas or liquid.

[0035] The radiator 3 can be cooled by air or liquid. Figure 2 and Figure 4 The air cooling method is shown as an example, and the side of the heat dissipation channel 31 away from the circuit board 2 is opened; Figure 3 and Figure 5 The figure shows the selected liquid cooling heat dissipation method, the heat dissipation channel 31 is closed on the side away from the circuit board 2, and the heat dissipation channel 31 is formed inside the radiator 3 to facilitate liquid flow to achieve heat dissipation.

[0036] like Figure 6 As shown, in one embodiment, a welding groove 32 is provided on one side of the heat sink 3 where the heat sink 3 is welded to the circuit board 2. The welding groove 32 is divided into a plurality of unit grooves 34 by a support portion 33. The top surface of the support portion 33 is at a first set distance from the top surface of the heat sink 3. Solder for welding the circuit board 2 and the heat sink 3 is arranged in the unit groove 34.

[0037] The support portion 33 is arranged below the top surface of the heat sink 3. When solder is arranged in each unit groove 34, the solder in each unit groove 34 is independent of each other, and the surface of the arranged solder is below the top surface of the heat sink 3 and above the support portion 33. Then, the arranged solder is heated to move the circuit board 2 toward the side close to the heat sink 3, and the circuit board 22 is moved a certain distance toward the side of the heat sink 3, so that the circuit board 2 is in contact with or separated from the support portion 33 by a certain gap. During the movement of the circuit board 2, the solder always flows in the soldering groove 32. The soldering groove 32 can limit the flow of the solder and prevent the solder from flowing to the outside of the bonding area between the circuit board 2 and the heat sink 3 (the projection area of ​​the circuit board 2 on the heat sink 3), further reducing the probability of generating voids in the solidified solder. For example, when the solder flows to the outside of the bonding area between the two, the solder in the bonding area between the circuit board 2 and the heat sink 3 will be reduced, which will increase the probability of generating voids. The method of arranging the solder includes coating the solder in each unit groove 34 with a mask plate, or preparing the solid solder into a shape matching the unit groove 34 and then placing it in the unit groove 34 .

[0038] like Figure 6-Figure 9 As shown, in one embodiment, the edge of the circuit board 2 is horizontally spaced from the edge of the welding slot 32 by a second set distance, and a limit block 35 for limiting the position of the circuit board 2 is provided in the welding slot 32 .

[0039] The size of the circuit board 2 is smaller than that of the soldering groove 32, and the stopper 35 is arranged on the support portion 33. When the circuit board 2 is placed on the arranged solder, the center of the circuit board 2 can be made to coincide with the center of the soldering groove 32 through the plurality of stopper blocks 35, so that the second set distance between each edge of the circuit board 2 and the corresponding edge of the soldering groove 32 is the same; the purpose of such arrangement is that after the solder is heated, the volatile substances in the solder will volatilize from the edges of the circuit board 2 and the soldering groove 32, so as to prevent the volatile substances from remaining in the solder and generating gaps; In addition, the size of the welding groove 32 is larger than the size of the circuit board 2, and each unit groove 34 of the welding groove 32 is filled with solder, thereby preventing the phenomenon of solder shortage at the edge of the circuit board 2 and ensuring that the amount of solder is sufficient to fill the bonding area between the circuit board 2 and the heat sink 3.

[0040] like Figure 7 and Fig. 9 As shown, in one embodiment, the support portion 33 includes: at least two cross-arranged support ribs 331, all of the support ribs 331 form an intersection A1, and the intersection A1 coincides with the vertical center line of the welding groove 32; each of the unit grooves 34 has at least one point on the circumscribed circle of the bottom surface of the welding groove 32, and this point is the set point A2, and the bottom surface of each of the unit grooves 34 is inclined downward along the set point A2 toward the direction of the intersection A1.

[0041] In this embodiment, the bottom surface of each unit groove 34 is set to be an inclined surface, so that the bottom surface of the welding groove 32 is an inclined surface with a low middle and high edges; For example, the supporting rib 331 divides the welding groove 32 into four unit grooves 34, and the four unit grooves 34 are rectangular. Then, the corner of the bottom surface of the unit groove 34 close to the intersection A1 is at the lowest position, and the corner close to the set point A2 is at the highest position.

[0042] Through the above scheme, when the arranged solder is heated, the solder will flow from a higher position to a lower position after it melts. At the same time, when the circuit board 2 moves toward the heat sink 3, it will form an extrusion effect on the molten solder, and the volatile substances in the solder will be discharged from the edges of the circuit board 2 and the heat sink 3. Since the bottom surface of the welding groove 32 is a slope with a low middle and high edges, the flow of the solder will not be affected by the extrusion effect, and it will still flow from the edge of the welding groove 32 to the middle. At the same time, the size of the welding groove 32 is larger than the size of the circuit board 2. In this way, it can be ensured that the bonding area is filled with solder, so that the volatile substances can also be discharged, reducing the generation of bubbles or gaps in the solder.

[0043] like Fig.10 and Fig.11 As shown, the present invention also provides a process for preparing a chip with a heat dissipation structure, comprising: A welding groove 32 is formed on one side of the heat sink 3, wherein the welding groove 32 is divided into a plurality of unit grooves 34 by a support portion 33, and the plurality of unit grooves 34 form a bottom surface of the welding groove 32 with a low middle and high edges; Arrange solder in each unit groove 34, and then position the circuit board 2 in the soldering groove 32; The solder is heated, and the circuit board 2 is moved toward the heat sink 3 , so that the circuit board 2 and the support portion 33 are spaced a third set distance apart.

[0044] Among them, arranging solder in each unit groove 34 includes: placing a mask plate at the soldering groove 32 of the heat sink 3, coating solder on the mask plate so that the solder covers each unit groove 34, and after the solder coating is completed, removing the mask plate and positioning the circuit board 2 in the soldering groove 32; or, placing solid solder of a corresponding shape in each unit groove 34.

[0045] Furthermore, the conditions for arranging solder in each unit groove 34 are: the top surface of the arranged solder is higher than the top surface of the support portion 33 , and the highest point of the solder after heating treatment is not higher than the top surface of the welding groove 32 .

[0046] The solder can be nano solder 8 or common solder 11 according to actual needs. The corresponding heating treatment method is selected according to the selected solder, so as to melt the solder so as to combine it with the circuit board 2 and the heat sink 3.

[0047] By selecting different types of solder, the volume change of the solder after melting and re-solidification is determined, and the height of the arranged solder and the distance range of the circuit board 2 moving close to the heat sink 3 are determined based on the volume change. Then, the preset range of the distance between the circuit board 2 and the support portion 33 can be obtained. The third set distance is selected within the preset range, and the maximum distance moved by the circuit board 2 (the minimum distance between the circuit board 2 and the support portion 33) is the contact between the circuit board 2 and the support portion 33.

[0048] For solder with poor fluidity, the height of the solder arrangement can be relatively low, and the circuit board 2 is Fig.10 The process shown moves to contact with the support portion 33, Fig.10 The figure shows the state after the solder arrangement is completed and the solder is melted and then solidified; For solder with good fluidity, the height of the solder can be relatively high, and the circuit board 2 is Fig.11 When the process shown moves to a third set distance from the support portion 33, the solder will fill the gap between the support portion 33 and the circuit board 22 under the guidance of the inclined surface of the soldering groove 32, thereby reducing the contact gap between the support portion 33 and the circuit board 22. Fig.11 The figure shows the state after the solder arrangement is completed and the solder melts and solidifies.

[0049] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0050] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the present invention, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A chip with a heat dissipation structure, characterized in that: include: A circuit board (2) for connecting components (1), wherein a heat sink (3) is connected to a side of the circuit board (2) away from the components (1), and the heat sink (3) and the circuit board (2) are connected by welding.

2. The chip with a heat dissipation structure according to claim 1, characterized in that: The circuit board (2) comprises: a circuit layer (4), an insulating layer (5) and a metal layer (6) which are connected to each other; the component (1) is connected to the circuit layer (4) via a solder paste layer (7); and the metal layer (6) is welded to the heat sink (3).

3. The chip with a heat dissipation structure according to claim 2, characterized in that: The metal layer (6) is made of copper or aluminum material, and the metal layer (6) is welded to the heat sink (3) via nano solder (8).

4. The chip with a heat dissipation structure according to claim 2, characterized in that: The metal layer (6) comprises: an aluminum layer (9); a copper or nickel plating layer (10) is provided on a side of the aluminum layer (9) away from the insulating layer (5); and the plating layer (10) is welded to the heat sink (3) by means of solder.

5. The chip with a heat dissipation structure according to claim 1, characterized in that: The radiator (3) is provided with a heat dissipation channel (31), and the heat dissipation medium passing through the heat dissipation channel (31) is gas or liquid.

6. The chip with a heat dissipation structure according to claim 1, characterized in that: A welding groove (32) is provided on one side of the heat sink (3) for welding to the circuit board (2); the welding groove (32) is divided into a plurality of unit grooves (34) by a support portion (33); a first set distance is provided between the top surface of the support portion (33) and the top surface of the heat sink (3); and solder for welding the circuit board (2) and the heat sink (3) is arranged in the unit groove (34).

7. The chip with a heat dissipation structure according to claim 6, characterized in that: The edge of the circuit board (2) and the edge of the welding groove (32) are separated by a second set distance in the horizontal direction, and a limit block (35) for limiting the position of the circuit board (2) is provided in the welding groove (32).

8. The chip with a heat dissipation structure according to claim 6, characterized in that: The support portion (33) comprises: at least two cross-arranged support ribs (331), all the support ribs (331) form an intersection (A1), and the intersection (A1) coincides with the vertical center line of the welding groove (32); the bottom surface of each unit groove (34) has at least one point on the circumscribed circle of the bottom surface of the welding groove (32), and this point is the set point (A2), and the bottom surface of each unit groove (34) is arranged to be inclined downward along the set point (A2) toward the intersection (A1).

9. A process for preparing a chip with a heat dissipation structure, characterized in that: A method for preparing a chip with a heat dissipation structure according to any one of claims 1 to 8, comprising: A welding groove (32) is formed on one side of the heat sink (3), wherein the welding groove (32) is divided into a plurality of unit grooves (34) by a support portion (33), and the plurality of unit grooves (34) enable the welding groove (32) to form a bottom surface with a low middle and high edges; Arranging solder in each unit groove (34), and then positioning the circuit board (2) in the soldering groove (32); The solder is heated and the circuit board (2) is moved in a direction close to the heat sink (3) so that the circuit board (2) and the support portion (33) are at a third set distance.

10. The process for preparing a chip with a heat dissipation structure according to claim 9, characterized in that: The conditions for arranging solder in each unit groove (34) are as follows: the top surface of the arranged solder is higher than the top surface of the support portion (33), and the highest point of the solder after heating is not higher than the top surface of the soldering groove (32).

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