POWER MODULE AND METHOD FOR MANUFACTURING THE SAME
A power module and a method for manufacturing the same are provided. The power module comprises: a substrate, at least one power device, and an organic heat dissipating structure. The substrate has an upper surface and a lower surface. The organic heat dissipating structure comprises a plane layer and a plurality of organic heat dissipating protrusions formed on a lower surface of the plane layer, wherein an upper surface of the plane layer is attached on the lower surface side of the substrate and configured to transfer heat generated by the power device outwardly.
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This application is a continuation of U.S. patent application Ser. No. 14/959,635 filed on Dec. 4, 2015, which is based on and claims priority to Chinese Patent Application No. 201410748695.1, filed on Dec. 9, 2014, the entire contents of which are incorporated herein by reference.
TECHNICAL FIELDThe present disclosure relates to a power module, and more particularly, to a power module having a structure for heat dissipation.
BACKGROUNDIn power supply industry, indicators for a power module, in particular for a power converter include high efficiency, high power density and high reliability. Then high efficiency means reduction of energy consumption, which is beneficial to energy conservation and emission reduction, as well as environment protection and reduction in use cost. The high power density means small volume and light weight, which could bring reduction in transportation cost and space requirement, thus leading to reduction in construction cost. Higher reliability is accompanied by longer service life and lower maintenance cost.
The above three indicators sought by the industry are closely linked with good thermal management. Firstly, at a lower operating temperature, conduction losses of a power module (e.g., Metal-Oxide-Semiconductor Field-Effect Transistor, MOSFET) may be reduced, which is beneficial to improving system efficiency.
Secondly, on many occasions, heat generated by a power device may directly influence its power density. Taking a power converter for an example, semiconductor devices therein typically have relatively large energy consumption. Therefore, the semiconductor devices may be considered as one of the most important factors determining efficiency of the power converter. Moreover, tolerable temperature of a semiconductor device has a certain limit, and the semiconductor device may be deteriorated sharply in performance or even disabled when the limit is exceeded. Therefore, it is vital important to provide a high-efficiency heat dissipating system capable of keeping temperature of a semiconductor chip within an acceptable range.
Thirdly, lifespan of the semiconductor device is also closely associated with the working temperature. A relatively lower operating temperature may enable a longer service life of the semiconductor device. Generally, there is such an engineering empirical rule in the electronic field that the lifespan of the device may be shortened by half for each 10° C. rise of the temperature. As can be known from above, the good thermal management is of critical importance in improving conversion efficiency, power density and reliability of the device.
Now, taking an example of a semiconductor device using DBC (Direct Bonded Copper) ceramic substrate as substrate, as shown in
The foregoing information is merely disclosed to facilitate understanding of background of the present disclosure. Therefore, the foregoing information may include information not constituting the prior art known to those of ordinary skill in the art.
SUMMARYAccording to one aspect of the present disclosure, it is provided a power module, including: a substrate having an upper surface and a lower surface at least one power device bonded to the upper surface of the substrate; and an organic heat dissipating structure comprising a plane layer and a plurality of organic heat dissipating protrusions formed on a lower surface of the plane layer, wherein an upper surface of the plane layer is attached on the lower surface side of the substrate and configured to transfer heat generated by the power device outwardly; wherein the organic heat dissipating protrusions and the plane layer are made from a same type of organic heat conduction material.
According to another aspect of the present disclosure, it is provided a method for manufacturing a power module, including: providing a substrate having an upper surface and a lower surface; providing at least one power device; bonding the at least one power device onto the upper surface of the substrate; and providing an organic heat dissipating structure including a plurality of organic heat dissipating protrusions on the upper surface side or the lower surface side of the substrate, the heat dissipating structure being configured to transfer heat generated by the power device outwardly.
By referring to detailed description of the drawings and exemplary embodiments, the foregoing and other characteristics and advantages of the present disclosure will become more apparent.
Exemplary embodiments will be described more comprehensively by referring to accompanying drawings. However, exemplary embodiments can be implemented in many forms It shall not be understood that the present disclosure is limited to embodiments as set forth herein; instead, these embodiments are provided to ensure the present disclosure to be more comprehensive and complete. And the conception of these exemplary embodiments shall be conveyed to those skilled in the art across-the-board. In the drawings, thickness of areas and layers is exaggerated for distinctness. The same numbers in drawings represent the same or similar structures, and thus detailed description thereof may be omitted.
Characteristics, structures or features as described may be incorporated into one or more embodiments in any suitable way. Many concrete details are provided in the following descriptions for a full understanding of embodiments of the present disclosure. However, those skilled in the art should realize that the technical solution of the present disclosure may be implemented without one or even more of specific details, and/or by using other alternative methods, components, materials and the like. In other circumstances, known structures, materials or operations are not shown or described in detail for the avoidance of fuzziness of various aspects of the present disclosure.
First of all, heat dissipation of the power module is explained as follows. Taking heat dissipation of a power semiconductor device in an air cooling system as an example, heat generated by the power semiconductor device is dissipated into ambient via two paths. In Path I, heat is transferred to a heatsink through a DBC substrate, and further to respective surfaces of the heatsink in heat exchange with the ambient, and finally dissipated into the ambient through those surfaces. In Path II, heat is transferred onto a surface of a molding component and dissipated into the ambient through the surface of the molding component. In order to explain influence of paths on heat dissipation, temperature monitor positions may he defined as below: a position of the power semiconductor device is defined as a junction, abbreviated to j; a point of the outside surface of the substrate corresponding to a midpoint of the power semiconductor device is defined as a case, abbreviated to c; the heatsink is defined as a heatsink, abbreviated to h; the ambient is defined as ambient, abbreviated to a; and a surface point of the molding component above the midpoint of the power semiconductor device is defined as molding, abbreviated to in. Accordingly, thermal resistances corresponding to each part may be abbreviated to following signs. Rjc: a thermal resistance from the junction to the case, Rch: a thermal resistance from the case to the heatsink, Rha: a thermal resistance from the heatsink to the ambient, Rjm: a thermal resistance from the junction to the molding, and Rma: a thermal resistance from the molding to the ambient. Similarly, temperature of each point may be also defined as Tv. For example, Tj stands for a temperature of the junction. Thus, thermal resistances and temperature monitor positions along the heat dissipation path may be illustrated in
Taking an example of the semiconductor device using a DBC (Direct Bonding Copper) substrate as shown in
A heat dissipating structure is provided so as to reduce heat transfer resistance between the heatsink and the ambient from another point of view in allusion to the foregoing bottleneck.
The First EmbodimentAs shown in
In an embodiment, the power device 110 and the substrate 130 are coated with a molding component, the power device 110 is bonded onto the substrate 130 by die bonding material (for example, a solder, a conductive adhesive, conductive sintering slurry, a thermal conductive adhesive and the like); the substrate 130 may be a PCB, a DBC, a lead frame, a metallized ceramic substrate or an insulated metal substrate (IMS substrate), etc. In some embodiments, the bottom side (i.e., the side near to the substrate 130) of the power device 110 has an electrode, for example, a vertical-type device, an flip chipped planar device, etc. The die bonding material usually needs to be electrically conductive, and usually a bonding pad (not shown) on the substrate 130 is corresponding to the die bonding material for realizing mechanical and electrical/thermal connection between the chip and the substrate. In some embodiments, regarding to a planar power device which is only provided with electrodes on the top side (i.e., the side far away from the substrate 130), the die bonding material between the planar power device and the substrate has thermal conductivity property. Electrical connection between the electrode on the front side of the power device and the substrate or a leading-out terminal may be realized by wire bonding, which is omitted in the accompanying drawing of the embodiment.
On some occasions, a power chip may be protected by the molding component for improving its reliability as the power chip is relatively fragile and is vulnerable to moisture, contamination and mechanical stress, etc. As shown in
In the embodiment, advantages of the present disclosure are further described by taking an example of applying an organic heatsink to a semiconductor power device using a DBC substrate (details of external pins and inner leads are omitted). However, application conditions of the present disclosure are not limited to this.
The heat dissipation effect of the organic heat dissipating structure 120 of the power module 100 in the present disclosure is explained by a group of comparative examples hereinafter.
As shown in
Although the organic heat dissipating protrusions are arranged with a large distribution density, there still are gaps allowing air flow among the organic heat dissipating protrusions. On the premise of ensuring good ventilation, areas of the organic heat dissipating protrusions shall be increased as far as possible for improving the heat dissipation efficiency.
Wherein, the organic heat dissipating protrusions 121 include an organic heat conduction material with a thermal conductivity between 0.2 w/m·K and 20 w/m·K. For example, the organic material may be provided by using organic materials (such as epoxy resin, acrylic acid, organic silicon and the like) as an insulated matrix in which insulating fillers with high thermal conductivity (such as aluminum oxide ceramic, silicon dioxide, aluminum nitride ceramic, graphite particles and metallic oxide particles, etc.) are doped. In this case, the organic heat dissipating protrusions serve as electrical insulators, free from short circuit resulted from being in contact with other electronic components, thus avoiding short-circuit fault in conventional design resulted from long fins of the heatsink made from materials with high thermal conductivity (such as copper). On some occasions where insulation is not necessary, the organic material serving as a matrix may he doped with metal particles with high thermal conductivity.
The organic heat dissipating protrusions 121 may be formed onto the upper surface and/or the lower surface of the power module by means of screen printing process, or by means of direct spraying or planting process (e.g., ultrasonic bonding, etc.).
Optionally, the organic heat dissipating protrusions 121 may be formed onto the surface of the power device or that of the substrate through film-pressing process, specifically including: providing a thermal conductive resin on the surface of the power device or that of the substrate, where the thermal conductive resin may be provided by using thermosetting organic material as a matrix and internally doped with a filler having high thermal conductivity for improving the thermal conductivity thereof, and the thermal conductive resin may present a form of liquid state or B-stage state (an intermediate stage in thermosetting resin reaction then, forming the organic heat dissipating protrusions in a. desirable shape by molds under high temperature and high pressure, thereby the thermal conductive resin is converted into a form of solid state.
Therefore, in the present disclosure, a mechanical fixed structure (for example, a spring clip, etc.) for fixing the power device and the organic heat dissipating structure may be omitted, thus avoiding extra space occupation and reducing the demands for surface evenness of the power device; besides, thermal efface materials may be omitted also, thus avoiding bad influence resulted from degradation of thermal conductivity property of thermal interface materials during long-term high temperature service process.
The Second EmbodimentReferring to
Referring to
Other parts of the third embodiment are approximately same as the first embodiment, not repeated any more herein.
The Fourth EmbodimentReferring to
Other parts of the fourth embodiment are approximately the same as the first embodiment, not repeated any more herein.
The Fifth EmbodimentReferring to
Other parts of the fifth embodiment are approximately the same as the first embodiment, not repeated any more herein.
As can be seen from above, the organic heat dissipating structure of the power module in the present disclosure may be provided with a bigger surface area. Therefore, the convective heat transfer resistance between the organic heat dissipating structure and the ambient may be substantially reduced, and further the heat dissipation performance of the organic heat dissipating structure may be improved. In addition, the organic heat dissipating structure of the power module in the present disclosure may, on the premise of ensuring normal heat dissipation of the power module, be reduced in its own height and space occupation. Particularly in constant pursuit of power density in the field of power supply, the requirement for reduction of a heatsink in size is becoming increasingly urgent. Compared with a conventional metal heatsink, the organic heat dissipating structure of the power module in the present disclosure is of great significance in realizing miniaturization of the power module.
Furthermore, the power module of the present disclosure needs neither a mechanical fixed structure (such as a spring clip and the like) to fix the organic heat dissipating structure and the power device nor thermal interface materials such as silicone grease, etc. So, problems in the prior art such as increases in entire thickness and design cost resulted thereby may be avoided,
in step 101, a power device and a substrate are provided to be covered by a molding component, wherein the substrate has an upper surface and a lower surface;
in step 102, an organic heat dissipating structure having a plurality of organic heat dissipating protrusions is formed, wherein the organic heat dissipating structure is located on the upper surface side or the lower surface side of the substrate and configured to transfer heat generated by the power device outwardly.
in step 201, a power device and a substrate are provided to be covered by a molding component; and
in step 202, an organic heat dissipating structure is formed on a surface of the molding component.
In the present embodiment, the heat generated by the power device is transferred outwardly through the organic heat dissipating structure via the molding component.
in step 5301, a plane layer is formed on the lower surface of the substrate by means of curing process, and
in step 5302, the organic heat dissipating protrusions is formed on a lower surface of the plane layer by means of printing or die casting process after the curing process.
in step 401, the organic heat dissipating protrusions are independently made; and
in step 402, the organic heat dissipating protrusions are attached onto the lower surface of the substrate through a plane layer.
in step 501, the organic heat dissipating protrusions are formed by means of any process selected from screen printing process, imprinting process, spraying or planting process, and film-pressing process.
Furthermore, in the present exemplary embodiment, the step of forming the organic heat dissipating protrusions by means of film-pressing process may include:
in step 502, a thermal conductive resin is provided on the lower surface of the substrate. Wherein the thermal conductive resin is provided with thermosetting organic material as a matrix and internally doped with a filler having high thermal conductivity, and the thermal conductive resin presents a form of liquid state or B-stage state; and
in step 503, the organic heat dissipating protrusions are formed, in a shape as required, by molds under high temperature and high pressure, wherein the thermal conductive resin is converted into a form of solid state.
It should be noted that, a lot of details described above in the embodiments of the power module are also applicable for implementing the embodiments of the method, and thus not repeated herein. Moreover, the sequence of steps described above is only for illustrative without any limitation, and can be modified as required according to actual needs.
What is mentioned above concretely illustrated and describes exemplary embodiments of the present disclosure. Nevertheless, it should be understood that the present disclosure is not limited to the embodiments disclosed herein. On the contrary, the present disclosure is intended to cover various modifications and equivalent arrangements within the spirit and scope of the appended claims.
Claims
1. A power module, comprising:
- a substrate having an upper surface and a lower surface;
- at least one power device bonded to the upper surface of the substrate; and
- an organic heat dissipating structure comprising a plane layer and a plurality of organic heat dissipating protrusions formed on a lower surface of the plane layer, wherein an upper surface of the plane layer is attached on the lower surface side of the substrate and configured to transfer heat generated by the power device outwardly;
- wherein the organic heat dissipating protrusions and the plane layer are made from a same type of organic heat conduction material.
2. The power module of claim 1, wherein the organic heat dissipating protrusions and the plane layer are from organic heat conduction material serving as filler material, the filler material being provided with an organic material as a matrix and doped with particles having high thermal conductivity.
3. The power module of claim 1, wherein the power device and the substrate are coated with a molding component, and the heat generated by the power device is transferred outwardly through the organic heat dissipating structure via the substrate.
4. The power module of claim 1, wherein the plane layer is formed on the lower surface of the substrate by means of curing process, and the organic heat dissipating protrusions are formed on a lower surface of the plane layer by means of printing or die casting process after the curing process.
5. The power module of claim 1, wherein the organic heat dissipating protrusions are formed in pillar bumps, cylinders or fins.
6. The power module of claim 5, wherein the organic heat dissipating protrusions are formed in multiple rows and two adjacent rows are arranged staggered or in line with each other.
7. The power module of claim 1, wherein the organic heat conduction material has a thermal conductivity between 0.2 w/m·K and 20 w/m·K.
8. The power module of claim 2, wherein the organic heat conduction material is selected from a group consisting of epoxy resin, acrylic acid and organic silicon, and the particles having high thermal conductivity are made from electrically insulated material selected from a group consisting of aluminum oxide ceramic, silicon dioxide, aluminum nitride ceramic, graphite, metallic oxide, and electrically conductive metal particles.
9. The power module of claim 1, wherein a thermal spread is sandwiched between the lower surface of the substrate and the upper surface of the plane layer, the thermal spread is made from material having high thermal conductivity.
10. A method for manufacturing a power module, comprising:
- providing at least one power device and a substrate having an upper surface and a lower surface; and
- forming an organic heat dissipating structure having a plurality of organic heat dissipating protrusions, wherein the organic heat dissipating structure is located on the upper surface side or the lower surface side of the substrate and configured to transfer heat generated by the power device outwardly.
11. The method of claim 10, further comprising:
- providing a molding component to cover the power device and the substrate,
- wherein the organic heat dissipating structure is formed on the lower surface of the substrate, and the heat generated by the power device is transferred outwardly through the organic heat dissipating structure via the substrate
12. The method of claim 10, further comprising:
- providing a molding component to cover the power device and the substrate; and
- forming the organic heat dissipating structure on a surface of the molding component,
- wherein the heat generated by the power device is transferred outwardly through the organic heat dissipating structure via the molding component.
13. The method of claim 10, wherein the step of forming an organic heat dissipating structure comprises:
- forming a plane layer on the lower surface of the substrate by means of curing process, and
- forming the organic heat dissipating protrusions on a lower surface of the plane layer by means of printing or die casting process after the curing process.
14. The method of claim 10, wherein the step of forming an organic heat dissipating structure comprises:
- independently making the organic heat dissipating protrusions; and
- attaching the organic heat dissipating protrusions onto the lower surface of the substrate through a plane layer.
15. The method of claim 10, wherein the step of forming an organic heat dissipating structure comprises:
- forming the organic heat dissipating protrusions by means of any process selected from screen printing process, imprinting process, spraying or planting process, and film-pressing process.
16. The method of claim 15, wherein the step of forming the organic heat dissipating protrusions by means of film-pressing process comprises:
- providing a thermal conductive resin on the lower surface of the substrate, the thermal conductive resin being provided with thermosetting organic material as a matrix and internally doped with a filler having high thermal conductivity, and the thermal conductive resin presenting a form of liquid state or B-stage state; and
- forming the organic heat dissipating protrusions, in a shape as required, by molds under high temperature and high pressure, wherein the thermal conductive resin is converted into a form of solid state.
Type: Application
Filed: Apr 3, 2019
Publication Date: Jul 25, 2019
Applicant: Delta Electronics,Inc. (Taoyuan City)
Inventors: Shouyu HONG (Taoyuan City), Zhenqing ZHAO (Taoyuan City)
Application Number: 16/373,984