Chip with heat dissipation structure and preparation process

Abstract

The present invention relates to the field of semiconductor technology, and discloses a chip with a heat dissipation structure and a preparation process, comprising: 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 connected by welding. The thermal conductivity of the circuit board is greater than that of a traditional PCB circuit board, and the circuit board and the heat sink are formed into an integrated structure by welding, which can reduce or avoid the formation of a 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 the heat sink connected by welding are more stable, preventing the formation of a gap between the two due to vibration, reducing thermal resistance, and improving the heat dissipation effect of the components.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and more particularly 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 increasing, especially power modules, which are becoming smaller and smaller. Due to the close arrangement of electronic components, heat generation is relatively concentrated in the equipment. If the heat cannot be effectively dissipated outward in a timely manner, the electronic equipment will cause various forms of failure due to long-term operation at high temperatures, which greatly limits the scope of use, service life and performance stability of electronic devices.

[0003] The most efficient way to transfer heat from a chip is through the pad, PCB, interface material, and heat sink. Traditional PCBs have a thermal conductivity of 0.2-5 W / (m·K). Chip heat is transferred to the heat sink through the PCB and thermal interface material.

[0004] A magnified view of the heat sink reveals noticeable unevenness on its surface. When the PCB and heat sink come into contact, a gap exists between them. Due to the poor heat transfer performance of air, this creates contact thermal resistance. When a large amount of heat passes through the contact surface, a large temperature difference is generated. Currently, thermal interface materials fill the contact surface, displacing air and reducing the contact thermal resistance. However, thermal interface materials such as thermal grease (thermal conductivity 1-8W / (m·K)) have limited thermal conductivity. Vibration between the power device and the housing can cause slight variations in the gap between the contact surfaces. This change in gap increases the thermal resistance.

[0005] When it comes to cooling high-power devices such as IGBTs (insulated-gate bipolar transistors), heat flux tends to increase with higher power and higher integration. The modules also generate significant amounts of heat due to their high-frequency conduction and switching. Overheating is a weakness of IGBT power semiconductor modules, making thermal management a key issue. The thermal conductivity of PCB materials and their thermal interface materials are bottlenecks in 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] The Summary of the Invention introduces a series of simplified concepts that will be further described in the Detailed Description of the Invention. The Summary of the Invention is not intended to limit the key features and essential features of the claimed technical solution, nor is it intended 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, comprising: a circuit board for connecting components, a heat sink connected to the 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 includes: 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 where the heat sink is welded to the circuit board, and the welding groove is divided into a plurality of unit grooves by a supporting portion, and a first set distance is placed between the top surface of the supporting portion and 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 the support ribs form an intersection, and the intersection coincides with the vertical center line of the welding groove; the bottom surface of 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 the set point, and the bottom surface of each of the unit grooves is tilted downward along the set point toward the intersection.

[0016] A process for preparing a chip with a heat dissipation structure, comprising:

[0017] 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 with a low middle and high edges;

[0018] Arrange solder in each unit groove, and then position the circuit board in the solder groove;

[0019] 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.

[0020] 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 part, and the highest point of the solder after heating treatment is not higher than the top surface of the soldering groove.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects:

[0022] The chip with a heat dissipation structure and the preparation process described in the present invention have a circuit board with a higher thermal conductivity than that of a traditional PCB circuit board, and the circuit board and the heat sink are formed into an integrated structure by welding, 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, preventing the formation of gaps between the two due to vibration, reducing thermal resistance, and improving the heat dissipation effect of components.

[0023] The chip with heat dissipation structure and preparation process described in the present invention, as well as other advantages, objectives and features of the present invention will be partially reflected in the following description, and will also be understood by those skilled in the art through research and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] 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:

[0025] Figure 1 A schematic diagram of the connection structure between the heat dissipation structure and the chip in the prior art;

[0026] 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;

[0027] 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;

[0028] Figure 4 This is a schematic diagram of the structure of the chip with heat dissipation structure according to the present invention using ordinary solder and air cooling;

[0029] Figure 5This is a schematic diagram of the structure of the chip with heat dissipation structure according to the present invention using ordinary solder and liquid cooling;

[0030] Figure 6 This is a schematic structural diagram of a soldering groove in a chip with a heat dissipation structure according to the present invention;

[0031] Figure 7 A schematic diagram of the positions of the intersection points and the set points in the soldering grooves of the chip with the heat dissipation structure according to the present invention;

[0032] Figure 8 This is a schematic top view of the chip with a heat dissipation structure according to the present invention;

[0033] Figure 9 For Figure 8 Schematic diagram of the cross-sectional structure at AA in the middle;

[0034] Figure 10 This is a schematic diagram of the position of a circuit board when solder with poor fluidity is used in the preparation process of the chip with a heat dissipation structure according to the present invention;

[0035] Figure 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 according to the present invention. DETAILED DESCRIPTION

[0036] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments so that those skilled in the art can implement the invention with reference to the description.

[0037] It should be understood that terms such as “having”, “including” and “comprising” used herein do not preclude the existence or addition of one or more other elements or combinations thereof.

[0038] 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 heat sink 3 through an interface material 14. The interface material 14 is generally thermal 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.

[0039] 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 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.

[0040] The circuit board 2 includes single-layer, double-layer, or multi-layer circuits. The material of the circuit board 2 includes one or more of the flame-resistant material FR4 (a grade code for flame-resistant materials), IMS (insulated metal substrate), ceramic board, and glass substrate. The thermal conductivity coefficient of the circuit board 2 is 0.2-200 W / (m·K).

[0041] 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.

[0042] 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 the 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.

[0043] like Figure 2 As shown, in one embodiment, the circuit board 2 includes: a circuit layer 4, an insulation layer 5 and a metal layer 6 that 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.

[0044] 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 high thermal conductivity coefficient. 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.

[0045] Furthermore, two options are provided for the selection of metal layer 6 and solder:

[0046] like Figure 2 and Figure 3 The first one is shown, where the metal layer 6 is made of copper or aluminum, and the metal layer 6 is welded to the heat sink 3 via nano solder 8 .

[0047] The metal layer 6 is made of copper or aluminum to improve the heat dissipation effect of the circuit board 2, while ensuring the welding bonding ability with the radiator 3. The nano-solder 8 can be made of nano-silver solder paste. The nano-solder 8 is coated on the surface of the radiator 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 radiator 3 and the circuit board 2 are bonded by sintering the nano-solder 8.

[0048] like Figure 4 and Figure 5The second type is shown, in which the metal layer 6 includes 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 soldered to the heat sink 3 by solder.

[0049] Among them, the solder uses any ordinary solder 11 that can weld the coating 10 and the radiator 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 radiator 3; when welding, the radiator 3, the pre-prepared solid ordinary solder 11 and the circuit board 2 can be stacked in sequence, and the ordinary solder 11 is melted by heating, and then solidified to combine the circuit board 2 and the radiator 3.

[0050] 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.

[0051] The radiator 3 can be cooled by air or liquid. Figure 2 and Figure 4 The air cooling method is shown as the selected one, and the side of the heat dissipation channel 31 away from the circuit board 2 is opened; Figure 3 and Figure 5 The liquid cooling method is selected. The heat dissipation channel 31 is closed on the side away from the circuit board 2. The heat dissipation channel 31 is formed inside the radiator 3 to facilitate liquid flow to achieve heat dissipation.

[0052] like Figure 6 As shown, in one embodiment, a welding groove 32 is provided on one side of the heat sink 3 where it 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.

[0053] The support portion 33 is set 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 lower than the top surface of the heat sink 3 and higher than 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 and the support portion 33 are in contact or separated 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 decrease, which will increase the probability of generating voids.

[0054] The solder arrangement includes coating the solder in each unit groove 34 using a mask plate, or preparing solid solder into a shape matching the unit groove 34 and then placing the solid solder in the unit groove 34 .

[0055] like Figure 6-Figure 9 As shown, in one embodiment, the edge of the circuit board 2 is horizontally spaced a second set distance from the edge of the welding slot 32 , and a limit block 35 for limiting the position of the circuit board 2 is provided in the welding slot 32 .

[0056] The size of the circuit board 2 is smaller than that of the soldering groove 32. The stoppers 35 are provided on the support portion 33. When the circuit board 2 is placed on the arranged solder, the multiple stoppers 35 enable the center of the circuit board 2 to coincide with the center of the soldering groove 32, so that each edge of the circuit board 2 is at the same second set distance from the corresponding edge of the soldering groove 32. This arrangement is intended to allow volatile substances in the solder to evaporate from the edges of the circuit board 2 and the soldering groove 32 after the solder is heated, thereby preventing the volatile substances from remaining in the solder and forming gaps.

[0057] 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 radiator 3.

[0058] like Figure 7 and Figure 9As 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 unit groove 34 is tilted downward along the set point A2 toward the intersection A1.

[0059] 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;

[0060] For example, the supporting rib 331 divides the welding groove 32 into four unit grooves 34 , and the four unit grooves 34 are rectangular. The corners of the bottom surface of the unit groove 34 close to the intersection A1 are at the lowest position, and the corners close to the set point A2 are at the highest position.

[0061] Through the above scheme, when the arranged solder is heated, the solder will flow from a higher position to a lower position after melting. 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 soldering 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 will still flow from the edge to the middle of the soldering groove 32. At the same time, the size of the soldering 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, thereby also being able to discharge the volatile substances and reduce the generation of bubbles or gaps in the solder.

[0062] like Figure 10 and Figure 11 As shown, the present invention also provides a process for preparing a chip with a heat dissipation structure, comprising:

[0063] 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 . The plurality of unit grooves 34 form a bottom surface of the welding groove 32 with a low center and high edges.

[0064] Arrange solder in each unit groove 34, and then position the circuit board 2 in the soldering groove 32;

[0065] 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.

[0066] Among them, arranging solder in each unit slot 34 includes: placing a mask plate at the soldering slot 32 of the heat sink 3, applying solder on the mask plate so that the solder covers each unit slot 34, and after the solder coating is completed, removing the mask plate and positioning the circuit board 2 in the soldering slot 32; or, placing solid solder of a corresponding shape in each unit slot 34.

[0067] 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 .

[0068] The solder can be nano solder 8 or ordinary 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.

[0069] By selecting different types of solder, the volume change of the solder after melting and resolidification is determined. The height of the arranged solder and the distance range of the circuit board 2 moving closer to the heat sink 3 are determined based on the volume change. Then, a 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. The maximum distance moved by the circuit board 2 (the minimum distance between the circuit board 2 and the support portion 33) is when it contacts the support portion 33.

[0070] For solder with poor fluidity, the height of the solder can be relatively low, and the circuit board 2 can be placed at a relatively low height. Figure 10 The process shown moves to contact with the support portion 33, Figure 10 The figure shows the state after the solder arrangement is completed and the solder melts and solidifies;

[0071] For solder with good fluidity, the height of the solder can be relatively high, and the circuit board 2 can be Figure 11 When the process shown is moved 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. Figure 11 The figure shows the state after the solder arrangement is completed and the solder melts and solidifies.

[0072] In the description of the present invention, it should 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" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0073] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0074] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with this field, 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 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; 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); The support portion (33) includes: 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 tilted downward along the set point (A2) toward the intersection (A1).

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) that are interconnected; the component (1) is connected to the circuit layer (4) via a solder paste layer (7); and the metal layer (6) is soldered 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) through 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: 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).

7. 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 6, 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 center 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.

8. The process for preparing a chip with a heat dissipation structure according to claim 7, 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 treatment is not higher than the top surface of the soldering groove (32).

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