CN118805450A - Cooling structure of power module - Google Patents

Abstract

A power module includes a first substrate, a first electronic component on a main surface of the first substrate, a second electronic component above the first electronic component, and a heat sink above the first electronic component. The first electronic component and the second electronic component are thermally connected, and the first electronic component and the heat sink are thermally connected. In a top view of the power module, at least a portion of one of the first electronic components overlaps with at least a portion of one of the second electronic components, and at least a portion of one of the first electronic components overlaps with a portion of the heat sink. In a side view of the power module, the second electronic component does not overlap with any portion of the heat sink.

Description

Cooling structure of power module

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No. 63/353,305, filed on June 17, 2022, and U.S. Provisional Application No. 63/440,164, filed on January 20, 2023. The entire contents of these applications are incorporated herein by reference.

Technical Field

The present invention relates to a power module, and more particularly to cooling a heat generating power element in the power module, thereby improving the performance of the power module.

Background Art

Known power modules include heat generating components, such as power elements of the power module. The heat generating components are typically spaced apart from other more thermally sensitive components at locations where cavities/voids are provided to allow for temperature isolation and heat dissipation of the heat generating components. For example, inductors near heat generating components may present problems since the inductors may have low thermal conductivity. Some of the heat generated in the heat generating components is also typically transferred through the substrate to a heat sink that can be connected to the carbon sheet.

For example, as shown in FIG. 1 , JP2020-205714 teaches a power converter 101 having a pair of circuit boards 10A and 10B, the pair of circuit boards 10A and 10B including a heat generating power component 14 and an inductor component 24. A conductive body 23 is disposed between the pair of circuit boards 10A and 10B, and heat sinks 40A and 40B are disposed adjacent to the pair of circuit boards 10A and 10B, respectively. Heat is transferred from the pair of circuit boards 10A and 10B to the conductive body 23 through a heat dissipation terminal block 50, and a heat sink 3 is fixed to the conductive body 23 to help remove heat from the conductive body 23. The heat generating power component 14 is spaced apart from the inductor component 24 and is arranged in an open gap between the pair of circuit boards 10A and 10B in an attempt to use the surrounding air to dissipate some of the heat generated by the heat generating power component 14.

However, these arrangements in known power modules require a lot of space, which is undesirable when miniaturization of the power module is required. In addition, if the heat-generating power component must be placed near the inductive component, this will reduce the cooling efficiency because the inductive component has a low thermal conductivity. When the cooling efficiency is reduced, the heat-generating power component will not be able to operate at a large current.

Summary of the invention

In order to overcome the above problems, a preferred embodiment of the present invention provides a power module that can be miniaturized while having sufficient cooling so that a large current can still be generated.

A preferred embodiment of the present invention provides a power module, which includes a first substrate, a first electronic component on a main surface of the first substrate, a second electronic component above the first electronic component, and a heat sink located above the first electronic component. The first electronic component and the second electronic component are thermally connected, and the first electronic component and the heat sink are thermally connected. In a top view of the power module, at least a portion of one of the first electronic components overlaps with at least a portion of one of the second electronic components in the second electronic component, and at least a portion of the one first electronic component overlaps with a portion of the heat sink. In a side view of the power module, the second electronic component does not overlap with any portion of the heat sink.

The first electronic component may include a power element.

The power module may further include a third electronic component located on the main surface of the first substrate. The third electronic component may include a capacitor.

The power module may further include a first thermally conductive material located between the first electronic component and the second electronic component. The first thermally conductive material may include a first carbon sheet. The power module may further include a second thermally conductive material located between the first electronic component and the heat sink. The second thermally conductive material may include a second carbon sheet. The first thermally conductive material and the second thermally conductive material may define a single layer.

The second electronic component may include an inductor. The top surface of the heat sink may be located above the top surface of the inductor. The heat sink may have electrical conductivity and thermal conductivity. The top surface of the second electronic component and/or the top surface of the heat sink may be at least partially molded within the housing.

A preferred embodiment of the present invention also provides a power module, which includes: a first substrate; a first electronic component and a second electronic component on the main surface of the first substrate; a second substrate above the first electronic component and the second electronic component; a third electronic component on the main surface of the second substrate; a fourth electronic component above the third electronic component; and a heat sink above the third electronic component. The third electronic component and the fourth electronic component are thermally connected, and the third electronic component and the heat sink are thermally connected. In a top view of the power module, at least a portion of one of the third electronic components overlaps with a portion of one of the fourth electronic components, and in a top view of the power module, at least a portion of one of the third electronic components overlaps with a portion of the heat sink. In a side view of the power module, the fourth electronic component does not overlap with any portion of the heat sink.

The first electronic component may include a capacitor. The second electronic component may include a conductive connecting pin. The power module may also include a fifth electronic component disposed on the main surface of the second substrate. The fifth electronic component may include a capacitor. The power module may also include a sixth electronic component disposed on another main surface of the second substrate, the other main surface being opposite to the main surface of the second substrate on which the third electronic component is disposed. The sixth electronic component may include a capacitor.

The above and other features, components, characteristics, steps and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the present invention with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of a known power supply module.

FIG. 2 shows a cross-sectional block diagram of a power module according to a first preferred embodiment of the present invention.

FIG. 3 shows a perspective view of a power module with a housing removed according to a first preferred embodiment of the present invention.

FIG. 4 shows a cross-sectional block diagram of a power module according to a second preferred embodiment of the present invention.

FIG. 5 shows a perspective view of a power module with a housing removed according to a second preferred embodiment of the present invention.

6 shows a perspective view of a power module with one of the second substrates, the housing, and the heat sink removed according to the second preferred embodiment of the present invention.

FIG. 7 is a cross-sectional block diagram showing a power module according to a modified example of the second preferred embodiment of the present invention.

FIG. 8 shows an example of a circuit diagram of a power module according to a third preferred embodiment of the present invention.

9 and 10 show a perspective view and a top view of a power module according to a fourth preferred embodiment of the present invention.

FIG. 11 shows an exploded view of the power module of FIG. 9 .

12 and 13 show a perspective view and a top view of the power module of FIG. 9 without a heat sink.

FIG. 14 shows a simulated thermal diagram of a power module according to a fifth preferred embodiment of the present invention.

FIG. 15 shows the power module used to create the simulated heat map of FIG. 14 .

DETAILED DESCRIPTION

First preferred embodiment

A power module according to a first preferred embodiment of the present invention will be described with reference to Figures 2 and 3. Figure 2 is a cross-sectional block diagram showing an example of an arrangement of components of a power module 1 according to a first preferred embodiment of the present invention. Figure 3 is a perspective view of an example of a power module 1 with a housing removed according to a first preferred embodiment of the present invention to show a possible arrangement of components of the power module 1.

As shown in FIG. 2 , the power module 1 may include a first substrate 10 , a heat conductive layer 20 (which may include at least one material layer), a housing 30 , a first electronic component 11 , a second electronic component 12 , a third electronic component 13 , and a heat sink 18 .

At least one first electronic component 11 and one third electronic component 13 are arranged on the main surface of the first substrate 11. A plurality of first electronic components 11 and a plurality of third electronic components 13 may be arranged on the main surface of the first substrate 11. The first electronic component 11 may be a higher heating element. For example, the first electronic component 11 may be a power element such as a transistor, an operational amplifier, an inverter, a diode, etc. The third electronic component 13 may be a smaller low heating element. For example, the third electronic component 13 may be a capacitor such as a surface mounted chip capacitor.

The heat sink 18 may be a single heat sink, or may be divided into a plurality of heat sinks that may or may not be in thermal contact with each other. The heat sink 18 may be made of a heat-conducting material such as a metal, including, for example, aluminum, copper, brass, or at least one alloy of aluminum, copper, and brass. The heat sink 18 may be manufactured by cutting, press working, die casting, and the like. The heat sink 18 may be fixed to the product using an adhesive, solder, and the like. The heat sink 18 may be provided with protrusions that may be used to fix the heat sink 18 in place by hooking the protrusions onto the ends of the substrate. Fixing the heat sink 18 to the ends of the substrate and bonding the heat sink may be performed at the same position.

A thermal interface material (TIM) may be interposed between the heat sink 18 and the first electronic component 11 .

The thermally conductive layer 20 may be disposed on the upper surface of the first electronic component 11. Depending on the application, the thermal conductivity of the thermally conductive layer 20 may be lower, higher, or equal to the thermal conductivity of the first substrate 10. The thermally conductive layer may include at least one material or layer, or may include two or more materials or layers combined together. For example, at least one material or layer may include one or more types of carbon sheets.

The heat sink 18 and at least one second electronic component 12 are disposed on the main surface of the thermally conductive layer 20. The heat sink 18 and multiple second electronic components 12 may also be disposed on the thermally conductive layer 20. The second electronic component 12 may be a larger, low-heat generating component. For example, the second electronic component 12 may be an inductor, which may have a lower thermal conductivity than the heat sink 18. The first electronic component 11 and the second electronic component 12 may be larger than the third electronic component 13. Arranging low-heat generating components (such as inductors) and heat sinks on the same layer while overlapping larger electronic components (such as power components and inductors) in the top view, and overlapping higher-heat generating components (such as power components) and heat sinks in the top view, helps to achieve miniaturization (e.g., a smaller footprint) while providing sufficient thermal coupling between high-heat generating components and heat sinks.

Another TIM may be inserted between the portion of each first electronic component 11 that overlaps the lower portion of the second electronic component 12. The thermal resistance may be large even if thermally coupled to the second electronic component 12. Therefore, a thermal conductive layer 20 may be inserted between the lower portion of the second electronic component and the first electronic component to facilitate heat diffusion to the heat sink 18.

The first electronic component 11, the second electronic component 12, and the heat sink 18 can be arranged so that: (i) when viewed from a top view of the power module 1, portions of the first electronic component 11 and the heat sink 18 overlap each other, and (ii) when viewed from a top view of the power module 1, portions of the first electronic component 11 and the second electronic component 12 overlap each other. Alternatively, the first electronic component 11, the second electronic component 12, and the heat sink 18 can be arranged so that: (i) when viewed from a top view of the power module 1, a portion of one first electronic component 11 and the heat sink 18 overlap each other, and (ii) when viewed from a top view of the power module 1, a portion of the first electronic component 11 and a portion of the second electronic component 12 overlap each other. The first electronic component 11 and the heat sink 18 can overlap at any overlap percentage. Due to these arrangements, and due to the thermally conductive layer 20, both the first electronic component 11 and the second electronic component 12 are effectively thermally connected to the heat sink 18. Although inductors generally have low thermal conductivity, including the thermally conductive layer 20 provides a path for moving heat from the second electronic component 12 to the heat sink 18. This efficient thermal connection produces an improved cooling effect, thereby increasing the performance of the power module 1 and enabling higher current output.

In addition, depending on the specific application, the first electronic component 11 and the third electronic component 13 may overlap or not overlap each other when viewed from the side of the power module 1. Depending on the specific application, the second electronic component 12 and the heat sink 18 may overlap or not overlap each other when viewed from the side of the power module 1.

Since the first electronic component 11 , the second electronic component 12 , and the heat sink 18 may be arranged in an overlapping arrangement in a top view of the power module 1 , the surface area of the first substrate 10 may be reduced, thereby facilitating miniaturization of the power module 1 .

The heat sink 18 can be made of a thermally and electrically conductive material. Suitable materials for the heat sink 18 include, for example, copper, aluminum, or other suitable materials. The top surface of the heat sink 18 can be located at a position higher than the top surface of the second electronic component 12. This arrangement allows heat to escape more easily to the outside of the power module 1 by defining a gap between the housing 30 and the second electronic component 12, wherein the housing 30 can be in contact with the upper surface of the heat sink 18 but not in contact with the second electronic component 12. In addition, this arrangement also helps to avoid failures caused by, for example, a short circuit or electrostatic discharge between the housing 30 and the second electronic component 12. The housing 30 can be made of, for example, aluminum, steel, copper, brass, or other suitable materials.

To further aid in heat dissipation, a top surface of second electronic component 12 and/or a top surface of heat sink 18 may be at least partially molded or embedded within a portion of housing 30 to enhance thermal conductivity between housing 30 , second electronic component 12 , and heat sink 18 .

FIG3 shows a perspective view of an example of a power module 1 with a housing removed according to a first preferred embodiment of the present invention. The housing is not shown in FIG3 . Here, a first electronic component 11 (power element) and a third electronic component 13 (chip capacitor) are arranged on the main surface of the first substrate 10. A heat conductive layer 20 (not visible in FIG3 because it is overlapped by other components) is arranged on the upper surface of the first electronic component 11, which is in contact with the lower surface of the second electronic component 12 (inductor) and the heat sink 18.

Second preferred embodiment

A power module according to a second preferred embodiment of the present invention will be described with reference to FIGS. 4 to 7 . FIG. 4 is a cross-sectional block diagram showing an example of an arrangement of components of a power module 2 according to a second preferred embodiment of the present invention. FIG. 5 is a perspective view of an example of a power module 2 according to a second preferred embodiment of the present invention with a housing removed to show a possible arrangement of components of the power module 2. The housing is not shown in FIG. 5 . FIG. 6 is another perspective view of an example of a power module 2 according to a second preferred embodiment of the present invention further including one of the first substrates 10 removed to show a possible arrangement of components of the power module 2. The housing is not shown in FIG. 6 .

As shown in FIG4 , the power module 2 according to the second preferred embodiment is different from the power module 1 according to the first preferred embodiment in that the first substrate 10 and the second substrate 100 are arranged in a stacked arrangement. The first substrate 10 may be stacked on top of the second substrate 100. The first substrate 10 may be a single substrate, or as shown in FIGS. 5 and 6 , the first substrate 10 may include two or more first substrates 10. Other configurations of the power module 2 according to the second preferred embodiment may be the same as the power module 1 according to the first preferred embodiment, and for the sake of brevity, descriptions of the same parts are omitted.

The arrangement of the first substrate 10, the first electronic component 11, the second electronic component 12, the third electronic component 13, the heat sink 18, the heat conducting layer 20 and the housing 30 of the second preferred embodiment may be the same or similar to the arrangement in the first preferred embodiment. The first substrate 10 may be mounted to the second substrate 100, with the fourth electronic component 14 and the fifth electronic component 15 interposed between the first substrate 10 and the second substrate 100. The fourth electronic component 14 may include a smaller low-heat generating component, including, for example, a capacitor, and the fifth electronic component 15 may include, for example, contact pins or other suitable connectors connecting the first substrate 10 and the second substrate 100.

The power module 2 may include a stack of substrates defined by a first substrate 10 and a second substrate 100. The first substrate 10 includes at least one third electronic component 13 disposed on a major surface of the first substrate 10. The second substrate 200 includes at least one fifth electronic component 15 disposed on a major surface of the second substrate 200. This arrangement allows for miniaturization of the power module 2, particularly when an additional chip capacitor is used in the power module 2.

The first substrate 10 may include at least one first electronic component 11 and one third electronic component 13 on a main surface, wherein a heat sink 18 and at least one second electronic component 12 are disposed on a main surface of a heat conductive layer 20 on the first electronic component 11. As with the power module 1, in the power module 2, the first electronic component 11, the second electronic component 12, and the heat sink 18 may be arranged such that: (i) when viewed from a top view of the power module 2, portions of the first electronic component 11 and the heat sink 18 overlap each other, and (ii) when viewed from a top view of the power module 2, portions of the first electronic component 11 and the second electronic component 12 overlap each other. Alternatively, the first electronic component 11, the second electronic component 12, and the heat sink 18 may be arranged such that: (i) when viewed from a top view of the power module 2, a portion of the first electronic component 11 and the heat sink 18 overlap each other, and (ii) when viewed from a top view of the power module 2, a portion of the first electronic component 11 and a portion of the second electronic component 12 overlap each other.

Including a stack of substrates defined by the first substrate 10 and the second substrate 100 in the power module 2 allows additional components to be included within a smaller footprint. However, by including a specific arrangement of the power module 2, an efficient thermal connection that produces better cooling can be provided, thereby improving the performance of the power module 2 and enabling greater current output.

Fig. 7 shows a modification of the power module 2A, in which the sixth electronic component 16 may be provided on the lower surface of the first substrate 10. This arrangement allows even further miniaturization while maintaining improved cooling.

The arrangement of the first substrate 10, the second substrate 100, the first electronic component 11, the second electronic component 12, the third electronic component 13, the fourth electronic component 14, the fifth electronic component 15, the heat sink 18, the heat conducting layer 20, and the housing 30 of the modification of the second preferred embodiment may be the same or similar to that in the second preferred embodiment. A sixth electronic component may be added to the bottom surface of the first substrate 10. The sixth electronic component 15 may be a small low-heat generating element, including, for example, a capacitor.

Third preferred embodiment

FIG8 shows a circuit diagram of a power module according to a third preferred embodiment of the present invention. The circuit diagram can be implemented in power modules according to other preferred embodiments (including the first preferred embodiment and the second preferred embodiment discussed above and the fourth preferred embodiment and the fifth preferred embodiment discussed below). The circuit diagram of FIG8 is only an example, and the power modules of other preferred embodiments can implement other power circuits or topologies.

The circuit diagram includes an input voltage V1, an input capacitor Cin, power stages 1, 2, 3, 4, inductors L1, L2, L3, L4, an output capacitor Cout, and a load I1. The input voltage V1 is connected to the input capacitor Cin. The power stages 1, 2, 3, 4 are connected to the input capacitor Cin. Although FIG8 shows four power stages, any number of power stages may be used. Each power stage 1, 2, 3, 4 includes a driver that drives two power switches Q1 and Q2, Q3 and Q4, Q5 and Q6, Q7 and Q8. Different topologies may have different numbers of power switches at each stage. Each power stage 1, 2, 3, 4 may be connected to a corresponding inductor L1, L2, L3, L4. The number of inductors may match the number of power stages. As shown in FIG8, inductors L1, L2, L3, L4 may be coupled. The inductors may be coupled by sharing a common core, such as shown in FIG6. In some applications, the inductors may not be coupled. Inductors L1, L2, L3, L4 are connected to an output capacitor Cout. Load I1 is connected to the output capacitor Cout.

Various components in the circuit diagram may be located in different areas of the power module. For example, the components of power stages 1, 2, 3, 4 (including drivers and power switches Q1 and Q2, Q3 and Q4, Q5 and Q6, Q7 and Q8) may be a first electronic component 11 on a first substrate 10; inductors L1, L2, L3, L4 may be a second electronic component 12, which is located above and at least partially overlaps the first electronic component 11; and input capacitor Cin and output capacitor Cout may be a third electronic component 13 on the first substrate 10, or as shown in FIG8, may be a fifth electronic component 15 and a sixth electronic component 16 between the first substrate 10 and the second substrate 100. A fourth electronic component 14 may be used to connect electronic components located on different substrates.

Fourth preferred embodiment

9 to 13 show a power module 2 according to a fourth preferred embodiment of the present invention. The power module 2 of FIGS. 9 to 13 is similar to the power module 2 of the second preferred embodiment, but includes eight first substrates 10 located above the second substrate 100. FIGS. 9 and 10 show a power module 2 without a housing but including a single heat sink 18. FIG. 11 is an exploded view showing the heat sink 18 above the first substrate 10. FIGS. 12 and 13 show a power module 2 without the heat sink 18. FIG. 12 does not show one of the first substrates 10, nor does it show the inductors on the other two first substrates 10.

The heat sink 18, the first electronic component 11, the second electronic component 12, and the third electronic component 13 are located above the first substrate 10. As shown in FIGS. 9 and 10, a single heat sink 18 may be located above all eight first substrates 10, and each first substrate 10 may include a separate first electronic component 11, second electronic component 12, and third electronic component 13. The fourth electronic component 14 may connect a different first substrate 10 to the second substrate 100. A fifth electronic component 15 (e.g., a capacitor) and possibly a sixth electronic component (e.g., a capacitor) (not shown in FIGS. 9 to 13) may be located between corresponding first substrates 10 in the first substrates 10 and the second substrate 100.

As shown in FIGS. 9 to 13 , the second substrate 100 may include one or more areas of the second substrate 100 that are not covered by the corresponding first substrate 10. Additional electronic components may be included in the uncovered areas. The additional electronic components may, for example, control the first electronic components 11. For example, if the first electronic component includes a power stage having a power switch and a driver for the power switch, the additional electronic component may include a controller that sends a control signal to the driver of the power stage.

Fifth preferred embodiment

FIG14 shows a thermal diagram of a power module 3 according to a fifth preferred embodiment of the present invention of FIG15. The power module 3 is similar to the power module 2 of the second preferred embodiment, and the power module 2 includes a first substrate 10 and a second substrate 100. A heat sink 18, a first electronic component 11 (e.g., a power element), a second electronic component 12 (e.g., an inductor), and a third electronic component 13 (e.g., a capacitor) are located above the first substrate 10. A fourth electronic component 14 may connect the first substrate 10 and the second substrate 100. A fifth electronic component 15 (e.g., a capacitor) may be located between the first substrate 10 and the second substrate 100.

The thermal diagram of FIG. 14 shows that overlapping both the second electronic component 12 and the heat sink 18 with the first electronic component 11 allows heat to flow from the first electronic component 11 and the second electronic component 12 to the heat sink 18 .

The configurations of the above-described preferred embodiments and modifications can be appropriately combined with each other, and effects corresponding to the respective combinations can be obtained.

It should be understood that the foregoing description is only for illustrating the present invention. Various substitutions and modifications may be devised by those skilled in the art without departing from the present invention. Therefore, the present invention is intended to include all such substitutions, modifications and variations that fall within the scope of the appended claims.

Claims (20)

1. A power module, comprising: a first substrate; a first electronic component on a major surface of the first substrate; a second electronic component above the first electronic component; and A heat sink is located above the first electronic component; wherein, The first electronic component and the second electronic component are thermally connected; The first electronic component is thermally connected to the heat sink; In a top view of the power module, at least a portion of one of the first electronic components overlaps with at least a portion of one of the second electronic components; In a top view of the power module, at least a portion of the one first electronic component overlaps a portion of the heat sink; and In a side view of the power module, the second electronic component does not overlap any portion of the heat sink. 2 . The power module of claim 1 , wherein the first electronic component comprises a power element. 3 . The power module according to claim 1 , further comprising a third electronic component located on the main surface of the first substrate. The power module according to claim 3 , wherein the third electronic component comprises a capacitor. 5 . The power module according to claim 1 , further comprising a first thermally conductive material located between the first electronic component and the second electronic component. The power module according to claim 5 , wherein the first thermally conductive material comprises a first carbon sheet. 7. The power module according to claim 5 or 6, further comprising a second thermally conductive material located between the first electronic component and the heat sink. 8 . The power module according to claim 7 , wherein the second thermally conductive material comprises a second carbon sheet. 9. The power module of claim 7 or 8, wherein the first thermally conductive material and the second thermally conductive material define a single layer. 10. The power module according to any one of claims 1 to 9, wherein the second electronic component comprises an inductor. 11 . The power module of claim 10 , wherein a top surface of the heat sink is located above a top surface of the inductor. 12 . The power module according to claim 1 , wherein the heat sink has electrical conductivity and thermal conductivity. 13. The power module according to claims 1 to 10, wherein a top surface of the second electronic component and/or a top surface of the heat sink is at least partially molded within the housing. 14. A power module, comprising: a first substrate and a second substrate, wherein the first substrate is located above the second substrate; a first electronic component on a major surface of the first substrate; a second electronic component, above the first electronic component; a fourth electronic component on the major surface of the second substrate; and A heat sink is located above the first electronic component; wherein: The first electronic component and the second electronic component are thermally connected; The first electronic component is thermally connected to the heat sink; In a top view of the power module, at least a portion of one of the first electronic components overlaps with a portion of one of the second electronic components; In a top view of the power module, at least a portion of the one first electronic component overlaps a portion of the heat sink; and In a side view of the power module, the second electronic component does not overlap any portion of the heat sink. 15. The power module of claim 14, wherein the fourth electronic component comprises a capacitor. 16 . The power module according to claim 14 , further comprising a conductive connecting pin, wherein the conductive connecting pin connects the first substrate and the second substrate. 17 . The power module according to claim 14 , further comprising a third electronic component disposed on the main surface of the first substrate. 18. The power module of claim 17, wherein the third electronic component comprises a capacitor. 19. The power module according to any one of claims 14 to 18, further comprising a sixth electronic component, the sixth electronic component being disposed on another main surface of the first substrate, the other main surface being opposite to the main surface of the first substrate on which the first electronic component is disposed. 20. The power module of claim 19, wherein the sixth electronic component comprises a capacitor.