A power device package structure

Abstract

This invention relates to the field of microelectronic component technology and discloses a power device packaging structure, comprising: a power chip; a substrate, the substrate being thermally coupled to the power chip, and the substrate having a cooling channel for the flow of a cooling medium. The cooling channel includes a flexible channel wall and a thermosensitive deformation layer, the thermosensitive deformation layer being disposed on the flexible channel wall. The thermosensitive deformation layer is configured to change its volume in response to temperature changes within the cooling channel, thereby changing the surface morphology of the flexible channel wall or the cross-section of the cooling channel to adaptively adjust the flow resistance characteristics of the cooling medium within the cooling channel. The power device packaging structure provided by this invention solves the problem in the prior art where a fixed microchannel structure leads to an inability to dynamically match the heat dissipation efficiency with the device's heating conditions.

Description

Technical Field

[0001] This invention relates to the field of microelectronic components technology, and in particular to a power device packaging structure. Background Technology

[0002] With the development of the energy internet, substation and distribution equipment is gradually moving towards miniaturization, high capacity, high integration, and high efficiency. However, with the continuous improvement of the integration and power density of power devices, the equipment faces severe thermal management challenges. Power chips inevitably generate a lot of heat during the process of power conversion and control, which leads to an increase in device junction temperature. Excessive temperature can directly cause device failure, seriously affecting the operational reliability and service life of power electronic equipment.

[0003] To reduce chip-level thermal resistance, existing power device heat dissipation solutions employ embedded liquid cooling technology that directly embeds microchannels into the chip substrate or package to shorten the heat dissipation path. However, existing embedded microchannel heat dissipation technology still has the following limitations: During operation, the heat generation of power devices is often uneven in different areas. Existing microchannel structures are usually rigid and fixed, and their flow resistance characteristics are constant, which can easily lead to a waste of cooling resources in low-temperature areas, while the cooling capacity may be insufficient in high-temperature hot spots. Summary of the Invention

[0004] The purpose of this invention is to provide a power device packaging structure that can change volume in response to temperature changes in the cooling channel by a thermosensitive deformation layer disposed on the flexible channel wall, thereby changing the surface morphology of the flexible channel wall or the cross-section of the cooling channel, and realizing adaptive adjustment of the flow resistance characteristics in the cooling channel. This solves the problem in the prior art where the fixed microchannel structure leads to the inability of heat dissipation efficiency to dynamically match the device's heating conditions.

[0005] To achieve the above objectives, the present invention provides a power device packaging structure, comprising: Power chip; A substrate is thermally coupled to the power chip, and the substrate is provided with a cooling channel for the flow of a cooling medium. The cooling channel includes a flexible channel wall and a thermosensitive deformation layer. The thermosensitive deformation layer is disposed on the flexible channel wall and is configured to change its volume in response to temperature changes within the cooling channel, thereby changing the surface morphology of the flexible channel wall or the cross-section of the cooling channel to adaptively adjust the flow resistance characteristics of the cooling medium within the cooling channel.

[0006] Furthermore, the flexible flow channel wall is provided with a plurality of mounting grooves that extend along the length of the cooling flow channel at intervals along its circumference, and the heat-sensitive deformation layer includes a plurality of deformation strips, which are embedded one-to-one in the plurality of mounting grooves, and the deformation strips are fixedly connected to the groove wall of the mounting groove.

[0007] Furthermore, the deformation strip has negative thermal expansion characteristics, and the elastic modulus of the deformation strip is greater than the elastic modulus of the flexible flow channel wall.

[0008] Furthermore, the flexible channel wall has a first hydrophobicity, the deformation strip has a second hydrophobicity, and the contact angle of the first hydrophobicity is greater than the contact angle of the second hydrophobicity.

[0009] Furthermore, the flexible flow channel wall is made of polydimethylsiloxane, and the deformation strip is made of a composite material of zirconium tungstate and epoxy resin.

[0010] Furthermore, the substrate is provided with a plurality of cooling channels, which are spaced apart on the side of the substrate near the power chip, and the cooling channels are microchannels embedded inside the substrate.

[0011] Furthermore, the substrate is also provided with an inlet channel and an outlet channel, the inlet channel being connected to one end of the plurality of cooling channels, and the outlet channel being connected to the other end of the plurality of cooling channels.

[0012] Furthermore, the power device packaging structure also includes a circuit board, with the front side of the power chip connected to the circuit board via a flip-chip bonding process, and the back side of the power chip connected to the substrate.

[0013] Furthermore, the power device packaging structure includes two circuit boards and two power chips, with one circuit board, the power chip, the substrate, the power chip, and the other circuit board connected sequentially along a first direction, and the cooling channel extending along a second direction; Wherein, the first direction and the second direction are perpendicular to each other.

[0014] Compared with existing technologies, the power device packaging structure of this invention has the following advantages: a thermosensitive deformation layer is provided on the flexible flow channel wall. Utilizing the characteristic that the thermosensitive deformation layer can change its volume in response to temperature changes within the cooling flow channel, the surface morphology of the flexible flow channel wall or the cross-section of the cooling flow channel changes, thereby achieving adaptive adjustment of the flow resistance characteristics within the cooling flow channel. It can automatically optimize the heat dissipation path based on the real-time heat generation of the power chip without the need for external sensors, micropumps, or controllers. This not only simplifies the complexity of the packaging structure and heat dissipation system but also effectively improves heat dissipation efficiency and energy utilization, ensuring the operational stability and reliability of the power device under different operating conditions. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the power device packaging structure according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the power device packaging structure from another angle according to an embodiment of the present invention; Figure 3 yes Figure 2 A magnified view of a section at point A in the middle; In the diagram, 1 is the power chip; 2 is the circuit board; 3 is the substrate; 31 is the cooling channel; 311 is the flexible channel wall; 3111 is the mounting groove; 312 is the thermosensitive deformation layer; 3121 is the deformation strip; 32 is the liquid inlet channel; and 33 is the liquid outlet channel. Detailed Implementation

[0016] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0017] In the description of this invention, the terms "upper," "lower," "left," "right," "front," "rear," "inner," "outer," "lateral," and "longitudinal," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are used only for the convenience of describing the invention and simplifying the description. They are not intended to limit the indicated devices, elements, or components to having a specific orientation, or to be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention. Those skilled in the art can understand the specific meaning of these terms in this invention according to the specific circumstances.

[0018] In the description of this invention, the terms "provided with," "set up," "connected," and "placed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, elements, or components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0019] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, elements, or components (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, elements, or components. Unless otherwise stated, "a plurality of" means two or more.

[0020] The technical solution of the present invention will be further described below with reference to the embodiments and accompanying drawings.

[0021] like Figure 1-3 As shown, an embodiment of the present invention provides a power device packaging structure, comprising: Power chip 1; Substrate 3 is thermally coupled to power chip 1, and substrate 3 is provided with cooling channel 31 for the flow of cooling medium. Cooling channel 31 includes flexible channel wall 311 and thermosensitive deformation layer 312. The thermosensitive deformation layer 312 is disposed on flexible channel wall 311 and is configured to change volume in response to temperature change in cooling channel 31, thereby changing the surface morphology of flexible channel wall 311 or cross-section of cooling channel 31 to adaptively adjust the flow resistance characteristics of cooling medium in cooling channel 31.

[0022] Based on the above technical solution, a thermosensitive deformation layer 312 is provided on the flexible flow channel wall 311. Utilizing the characteristic that the thermosensitive deformation layer 312 can change its volume in response to temperature changes within the cooling flow channel 31, the surface morphology of the flexible flow channel wall 311 or the cross-section of the cooling flow channel 31 changes, thereby achieving adaptive adjustment of the flow resistance characteristics within the cooling flow channel 31. This enables automatic optimization of the heat dissipation path based on the real-time heat generation of the power chip 1 without the need for external sensors, micropumps, or controllers. This not only simplifies the complexity of the packaging structure and heat dissipation system but also effectively improves heat dissipation efficiency and energy utilization, ensuring the operational stability and reliability of the power device under different operating conditions.

[0023] Preferably, the flexible flow channel wall 311 is provided with a plurality of mounting grooves 3111 extending along the length direction of the cooling flow channel 31 at intervals along its circumference, and the heat-sensitive deformation layer 312 includes a plurality of deformation strips 3121, which are embedded one-to-one in the plurality of mounting grooves 3111, and the deformation strips 3121 are fixedly connected to the groove wall of the mounting groove 3111.

[0024] The interlocking structure of the mounting groove 3111 and the deformation strip 3121 forms a robust mechanical interlock. Under conditions of high-speed flow of the cooling medium or pressure fluctuations, it can effectively prevent the heat-sensitive deformation layer 312 from peeling or falling off due to fluid shear force, thereby ensuring the long-term operational reliability of the encapsulation structure. The fixed connection ensures that the deformation stress of the deformation strip 3121 can be directly transferred to the flexible flow channel wall 311, improving the efficiency of deformation response. The deformation strip 3121 extends along the length of the cooling flow channel 31, making the flexible flow channel wall 311 exhibit significant anisotropy when deformed. This allows the cooling flow channel 31 to undergo large expansion or bending deformation in the radial direction to change its cross-sectional area, while maintaining a relatively stable shape in the axial direction. This avoids obstructing fluid flow due to excessive overall twisting. The dispersed strip structure can better release the internal stress caused by the mismatch of thermal expansion coefficients.

[0025] More preferably, the deformation strip 3121 has negative thermal expansion characteristics, and the elastic modulus of the deformation strip 3121 is greater than the elastic modulus of the flexible flow channel wall 311.

[0026] By using a material with negative thermal expansion properties to make the deformation strip 3121, when the power chip 1 heats up and the temperature of the cooling channel 31 rises, the deformation strip 3121 with negative thermal expansion properties shrinks in volume. This volume shrinkage causes a redistribution of the surface area ratio of the inner wall of the cooling channel 31. As the deformation strip 3121 shrinks, the high elastic modulus deformation strip 3121 plays a role in structural reinforcement in the channel. The relatively low elastic modulus flexible channel wall 311 undergoes extension deformation under the flow pressure and thermal stress of the cooling medium, so that the flexible channel wall 311 occupies a larger surface area or space ratio in the cooling channel 31. The contact surface dominated by the flexible structure can better buffer and adapt to the impact generated by the high-speed flowing cooling medium, reduce the turbulence loss of the fluid under the rigid boundary, and thus effectively improve the overall cooling efficiency while adapting to the passage of a larger flow rate of cooling medium.

[0027] More preferably, the flexible channel wall 311 has a first hydrophobicity, the deformable strip 3121 has a second hydrophobicity, and the contact angle of the first hydrophobicity is greater than the contact angle of the second hydrophobicity.

[0028] When the temperature rises and triggers the volume contraction of the deformation strip 3121, the surface area ratio of the flexible flow channel wall 311 on the inner wall of the cooling flow channel 31 increases. Since the flexible flow channel wall 311 has better primary hydrophobicity, its increased ratio directly leads to an increase in the overall effective contact angle of the inner wall of the cooling flow channel 31. The surface properties of the cooling flow channel 31 are no longer static, but can dynamically change their hydrophobicity with temperature changes. Under the high temperature and high load conditions of the power chip 1, the inner wall of the cooling flow channel 31 automatically converts to a highly hydrophobic state, reducing the shear stress between the cooling medium and the wall of the cooling flow channel 31, and reducing the friction loss. Under the premise that the pumping pressure of the cooling medium remains unchanged, the reduction of flow resistance directly translates into an increase in flow velocity and flow rate, thereby enhancing the convective heat transfer effect.

[0029] More preferably, the flexible flow channel wall 311 is made of polydimethylsiloxane, and the deformable strip 3121 is made of a composite material of zirconium tungstate and epoxy resin.

[0030] It should be noted that the specific material selections described above are merely preferred embodiments of the present invention and are not the only limitation on the scope of protection of the present invention.

[0031] For the flexible flow channel wall 311, those skilled in the art can select other flexible polymer materials with good elastic deformation ability, chemical stability and compatibility with cooling media according to actual process requirements, such as, but not limited to: silicone rubber, polyimide, polyurethane or other polymer substrates with similar low elastic modulus properties.

[0032] Similarly, the deformation strip 3121 is not limited to a composite material of zirconium tungstate and epoxy resin. Any material with negative thermal expansion characteristics and an elastic modulus that meets the requirements for driving the deformation of the flexible flow channel wall 311 can be used in this invention. For example, other negative thermal expansion fillers such as hafnium tungstate and zinc cyanide can be used, or a structure with an equivalent negative thermal expansion effect based on metamaterial structure design can be used.

[0033] Preferably, the substrate 3 is provided with a plurality of cooling channels 31, which are distributed at intervals on the side of the substrate 3 near the power chip 1, and the cooling channels 31 are microchannels embedded in the substrate 3.

[0034] In one specific embodiment, the substrate 3 is made of polydimethylsiloxane.

[0035] More preferably, the substrate 3 is further provided with an inlet channel 32 and an outlet channel 33, the inlet channel 32 being connected to one end of a plurality of cooling channels 31, and the outlet channel 33 being connected to the other end of a plurality of cooling channels 31.

[0036] Combined with the aforementioned thermosensitive deformation adaptive structure, the array distribution of multiple cooling channels 31 has a zoned independent adjustment function. Since the current density distribution on the surface of the power chip 1 is often uneven during actual operation, local hot spots may appear. Each independent microchannel is only affected by the temperature of its corresponding local area. When a local hot spot appears in a certain part of the power chip 1, the cooling channel 31 corresponding to the hot spot will be triggered by the temperature rise to shrink the deformation strip 3121 and reduce the flow resistance. Meanwhile, the channels below the lower temperature area remain unchanged, realizing precise cooling of the hot spot area, more efficiently suppressing the temperature gradient on the surface of the power chip 1, and ensuring the temperature uniformity and reliability of the power chip 1.

[0037] More preferably, the power device packaging structure also includes a circuit board 2, the front side of the power chip 1 is connected to the circuit board 2 by a flip-chip bonding process, and the back side of the power chip 1 is connected to the substrate 3.

[0038] More preferably, the power device packaging structure includes two circuit boards 2 and two power chips 1. One circuit board 2, power chip 1, substrate 3, power chip 1 and the other circuit board 2 are connected in sequence along the first direction X, and the cooling channel 31 extends along the second direction Y. In this context, the first direction X and the second direction Y are perpendicular to each other.

[0039] By placing power chips 1 on both sides of the substrate 3, a single cooling unit (i.e., the substrate 3 and its internal cooling channel 31) can simultaneously serve two power chips 1. Sharing a cooling source improves the power handling capability of the package structure without significantly increasing the package volume, meeting the requirements of miniaturization and high integration of power electronic equipment. The symmetrical structural design along the first direction X ensures that the thermal expansion stress on both sides of the substrate 3 is mutually balanced. Compared with single-sided package structures that are prone to warping due to heating on one side, double-sided stacking can effectively offset some of the thermal mismatch stress, maintaining the mechanical flatness and connection of the package. Reliability: The substrate 3 is made of polydimethylsiloxane, which has the material properties of low elastic modulus and high flexibility. Combined with the pressing force of the stacked structure, the substrate 3 can achieve adaptive bonding to the surface of the power chip 1. The substrate 3 can fill the microscopic unevenness of the surface of the power chip 1, reduce or even eliminate the small air gap between the chip and the substrate 3, thereby significantly reducing the contact thermal resistance. During the operation of the power chip 1, the hot spot area is often accompanied by local thermal expansion. The flexible substrate 3 can undergo elastic deformation to fit the hot spot expansion area of ​​the power chip 1, thereby ensuring efficient heat dissipation of the core heat-generating area.

[0040] In summary, this invention provides a power device packaging structure with a thermosensitive deformation layer 312 on the flexible channel wall 311. Utilizing the characteristic that the thermosensitive deformation layer 312 can change volume in response to temperature changes within the cooling channel 31, the surface morphology of the flexible channel wall 311 or the cross-section of the cooling channel 31 changes. This achieves adaptive adjustment of the flow resistance characteristics of the cooling medium within the cooling channel 31. Without the need for external sensors, micropumps, or controllers, it can automatically optimize the heat dissipation path based on the real-time heat generation of the power chip 1. This not only simplifies the complexity of the packaging structure and heat dissipation system but also effectively improves heat dissipation efficiency and energy utilization, ensuring the operational stability and reliability of the power device under different operating conditions.

[0041] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A power device package structure, characterized by, include: Power chip (1); The substrate (3) is thermally coupled to the power chip (1), and the substrate (3) is provided with a cooling channel (31) for the flow of cooling medium. The cooling channel (31) includes a flexible channel wall (311) and a thermosensitive deformation layer (312). The thermosensitive deformation layer (312) is disposed on the flexible channel wall (311). The thermosensitive deformation layer (312) is configured to change its volume in response to temperature changes in the cooling channel (31), thereby changing the surface morphology of the flexible channel wall (311) or the cross-section of the cooling channel (31) to adaptively adjust the flow resistance characteristics of the cooling medium in the cooling channel (31).

2. The power device package structure of claim 1, wherein, The flexible flow channel wall (311) is provided with a plurality of mounting grooves (3111) that extend along the length of the cooling flow channel (31) at intervals along its circumference. The heat-sensitive deformation layer (312) includes a plurality of deformation strips (3121). The plurality of deformation strips (3121) are embedded in the plurality of mounting grooves (3111) one by one, and the deformation strips (3121) are fixedly connected to the groove wall of the mounting groove (3111).

3. The power device packaging structure according to claim 2, characterized in that, The deformation strip (3121) has negative thermal expansion characteristics, and the elastic modulus of the deformation strip (3121) is greater than that of the flexible flow channel wall (311).

4. The power device packaging structure according to claim 2, characterized in that, The flexible channel wall (311) has a first hydrophobicity, and the deformation strip (3121) has a second hydrophobicity, wherein the contact angle of the first hydrophobicity is greater than the contact angle of the second hydrophobicity.

5. The power device package structure of claim 4, wherein, The flexible flow channel wall (311) is made of polydimethylsiloxane, and the deformation strip (3121) is made of a composite material of zirconium tungstate and epoxy resin.

6. The power device package structure of claim 1, wherein, The substrate (3) is provided with a plurality of cooling channels (31), and the plurality of cooling channels (31) are distributed at intervals on the side of the substrate (3) near the power chip (1). The cooling channels (31) are microchannels embedded in the substrate (3).

7. The power device package structure of claim 6, wherein, The substrate (3) is also provided with an inlet channel (32) and an outlet channel (33). The inlet channel (32) is connected to one end of the plurality of cooling channels (31), and the outlet channel (33) is connected to the other end of the plurality of cooling channels (31).

8. The power device package structure of claim 6, wherein, It also includes a circuit board (2), the front side of the power chip (1) is connected to the circuit board (2) by flip-chip bonding, and the back side of the power chip (1) is connected to the substrate (3).

9. The power device package structure of claim 8, wherein, It includes two circuit boards (2) and two power chips (1). One circuit board (2), the power chip (1), the substrate (3), the power chip (1), and the other circuit board (2) are connected in sequence along a first direction (X), and the cooling channel (31) extends along a second direction (Y). Wherein, the first direction (X) and the second direction (Y) are perpendicular to each other.

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