Pcb package power module integrated with absorption capacitor and manufacturing method thereof
Patent Information
- Application Number
- CN202611233623.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-08-14
- Publication Date
- 2026-10-27
AI Technical Summary
[0004]本发明的目的是提供一种集成吸收电容的PCB封装功率模块及其制备方法，以解决现有技术中外置吸收电容换流回路长、杂感大，吸收尖峰能力弱，同时散热效率差、占用额外空间不利于系统小型化的技术问题
本发明的集成吸收电容的PCB封装功率模块通过将功率芯片嵌入PCB中，吸收电容通过表贴放置在PCB上表面，大幅缩短换流回路长度，降低回路杂感，能够更好的吸收功率器件开关过程中的振荡和电压尖峰，达到相同吸收效果的情况下可降低吸收电容使用量。吸收电容表贴在PCB上，下方即为陶瓷覆铜基板和散热器，散热效果远优于传统布置中散热效率较差的空气对流换热，降低应用过程中吸收电容的温度，提高使用寿命。相较于现有技术中吸收电容布置在模块外部的连接铜排上需额外占用部分面积，本发明通过将吸收电容放置在芯片上方，降低了布置吸收电容带来的体积占用，降低了系统体积，有助于进一步提升系统功率密度。
Smart Images
Figure CN122995022A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of PCB packaged power module technology, specifically relating to a PCB packaged power module with integrated absorption capacitor and its preparation method. Background Technology
[0002] Currently, as applications demand increasingly higher power levels, smaller size and weight, and lower costs, traditional power module packaging is finding it increasingly difficult to meet these needs. Furthermore, for third-generation semiconductor applications, integrating driver functions with other features such as protection, temperature and current monitoring is becoming a growing trend. Among these features, the absorption capacitor is a crucial component of module protection, serving to reduce voltage and current spikes and absorb oscillations.
[0003] See Figure 1 Traditional modules often use external absorption capacitors in applications. These are connected to the positive and negative terminals of the module via connecting copper busbars. A PCB board is then placed between the connecting copper busbars, and the absorption capacitors are mounted on the board. This approach has the following drawbacks: 1. The commutation circuit is relatively long, and the commutation needs to pass through the entire module plus part of the connecting copper busbar. The circuit has a large amount of noise inductance and a weak ability to absorb voltage and current spikes. Therefore, multiple absorption capacitors are often used in parallel when arranging them. 2. The absorption capacitor is connected to the connecting copper busbar, and cannot be directly or indirectly connected to the heat sink. It can only dissipate heat through convection in the air, which results in extremely poor heat dissipation efficiency. 3. It requires a certain area to be used, which is not conducive to reducing the system size. Summary of the Invention
[0004] The purpose of this invention is to provide a PCB-packaged power module with an integrated absorption capacitor and its manufacturing method, so as to solve the technical problems of the existing technology where the external absorption capacitor has a long commutation circuit, large stray inductance, weak peak absorption capability, poor heat dissipation efficiency, and occupies extra space, which is not conducive to system miniaturization.
[0005] This application provides a PCB-packaged power module with an integrated absorption capacitor, comprising: A molding compound comprising a ceramic copper-clad substrate and molding compound encapsulating the periphery and top of the ceramic copper-clad substrate; the upper surface of the ceramic copper-clad substrate is provided with a chip and a thin copper sheet. A prepreg layer located above the molding compound, and said prepreg layer having copper through-holes; A copper layer located above the prepreg layer; Solder mask layer, covering the copper layer, with several solder pads exposed; An absorption capacitor is connected to the pad.
[0006] In one embodiment of this application, the ceramic copper-clad substrate includes an upper copper layer, an intermediate ceramic layer, and a lower copper layer stacked together. The chip and thin copper sheet are disposed on the upper surface of the upper copper layer, and the upper ends of the chip and thin copper sheet are exposed in the molding compound.
[0007] In one embodiment of this application, the lower surface of the lower copper layer is exposed in the molding compound.
[0008] In one embodiment of this application, the thickness of the lower copper layer is greater than the thickness of the upper copper layer.
[0009] In one embodiment of this application, the thickness of the lower copper layer is 0.05 mm to 0.3 mm greater than the thickness of the upper copper layer, preferably 0.1 mm.
[0010] In one embodiment of this application, the pad is also connected to a corresponding terminal.
[0011] In one embodiment of this application, the absorption capacitor is a surface-mount capacitor.
[0012] Accordingly, this application also provides a method for fabricating a PCB-packaged power module with an integrated absorption capacitor, comprising: Prepare a ceramic copper-clad substrate; the ceramic copper-clad substrate includes an upper copper layer, an intermediate ceramic layer and a lower copper layer stacked together, and the thickness of the lower copper layer is greater than the thickness of the upper copper layer; The upper copper layer is divided into multiple regions according to the circuit topology; among them, a connection material layer is set at the chip mounting position, and several thin copper sheets are set on the outer periphery of the chip mounting position. The ceramic copper-clad substrate is encapsulated around its perimeter and top to form a molded body. After encapsulation, the lower copper layer is exposed outside the molded body, while the upper copper layer is completely covered. A chip mounting window is provided in the area of the bonding material layer. Remove a certain thickness from the top surface of the molding compound to expose a thin copper sheet, so that the two are ultimately at the same height; The chip is attached to the bonding material layer, and the height of the chip's upper surface is slightly lower than the height of the upper surface of the molding compound. The height difference should be controlled within 10-50 μm. Prepare a core board with through holes, the size of which is slightly larger than the size of the molding compound, and the thickness of the core board is the same as the thickness of the molding compound. Embed the molding compound into the core board. The gap between the inner wall of the through hole and the outer wall of the molding compound is controlled between 25-100 μm. The prepreg layer and copper layer are laminated onto the core board. Holes are drilled at appropriate positions above the chip and the thin copper sheet, and then electroplated to fill them, forming an electrical connection. The laminated copper layer is divided into multiple pieces according to functional requirements; Apply a solder mask layer to cover the parts that need to be electrically connected to the outside, leaving the pads for soldering terminals or other components. Remove the core board; Welding connection terminals and absorption capacitors.
[0013] The beneficial effects of this invention are: The integrated absorption capacitor PCB-packaged power module of this invention embeds the power chip into the PCB, while the absorption capacitor is surface-mounted on the upper surface of the PCB. This significantly shortens the commutation loop length, reduces loop noise, and better absorbs oscillations and voltage spikes during the switching process of power devices. It achieves the same absorption effect while reducing the amount of absorption capacitor required. With the absorption capacitor surface-mounted on the PCB, the ceramic copper-clad substrate and heat sink are located below, resulting in significantly better heat dissipation than the poorly efficient air convection heat transfer in traditional layouts. This reduces the temperature of the absorption capacitor during application and extends its lifespan. Compared to existing technologies where the absorption capacitor is placed on the external copper busbar, requiring additional space, this invention places the absorption capacitor above the chip, reducing the volume occupied by the absorption capacitor, thus reducing the system size and contributing to further improvements in system power density.
[0014] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained through the structures particularly pointed out in the description and the drawings.
[0015] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description
[0016] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0017] Figure 1 This is the existing method of setting up the absorption capacitor; Figure 2 This is a cross-sectional view of a PCB-packaged power module according to a preferred embodiment of the present invention; Figure 3 This is a schematic diagram of a preferred embodiment of the ceramic copper-clad substrate of the present invention; Figure 4 This is a schematic diagram of a preferred embodiment of the encapsulation body of the present invention; Figure 5 This is a schematic diagram of the encapsulation body after chip mounting according to a preferred embodiment of the present invention; Figure 6 This is a schematic diagram of a core board according to a preferred embodiment of the present invention; Figure 7 This is a schematic diagram of a preferred embodiment of the present invention after pressing together the prepreg layer and the copper layer; Figure 8 This is a schematic diagram of a preferred embodiment of the present invention after drilling and electroplating; Figure 9 This is a schematic diagram of a preferred embodiment of the present invention after the copper layer has been segmented; Figure 10 This is a circuit topology diagram of a PCB-packaged power module according to a preferred embodiment of the present invention; Figure 11 According to Figure 10 A schematic diagram of the circuit topology retaining the pads; Figure 12 According to Figure 10 A schematic diagram of the circuit topology after soldering capacitors and terminals; Figure 13 This is a circuit topology diagram of a PCB-packaged power module according to another preferred embodiment of the present invention; Figure 14 According to Figure 13 A schematic diagram of the circuit topology retaining the pads; Figure 15 According to Figure 13 A schematic diagram of the circuit topology after soldering capacitors and terminals.
[0018] In the picture: Core board 1, through hole 11, molding compound 2, ceramic copper clad substrate 21, upper copper layer 211, middle ceramic layer 212, lower copper layer 213, connecting material layer 214, molding compound 22, chip 3, thin copper sheet 4, prepreg layer 5, copper layer 6, solder mask layer 7, pad 8, absorption capacitor 9, terminal 10. Detailed Implementation
[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0020] This application provides a PCB-packaged power module with integrated absorption capacitor and its fabrication method, which are described in detail below. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments of this application. Furthermore, the descriptions of each embodiment have their own emphasis; parts not described in detail in a certain embodiment can be referred to in the relevant descriptions of other embodiments.
[0021] See Figure 2 , Figure 12 and Figure 15 In one embodiment, the PCB packaged power module with integrated absorption capacitor includes: a molding compound 2, which includes a ceramic copper-clad substrate 21 and molding compound 22 encapsulated around and on the top of the ceramic copper-clad substrate 21; a chip 3 and a thin copper sheet 4 are disposed on the upper surface of the ceramic copper-clad substrate 21; a prepreg layer 5 located above the molding compound 2, and copper through-holes are disposed in the prepreg layer 5; a copper layer 6 located above the prepreg layer 5; a solder resist layer 7 covering the copper layer 6 and exposing a plurality of pads 8; and an absorption capacitor 9 connected to the pads 8.
[0022] In this embodiment, by directly integrating the absorption capacitor onto the PCB structure inside the power module, there is no need to arrange the absorption capacitor and connecting copper busbar outside the module. This significantly shortens the commutation loop length from the absorption capacitor to the chip and effectively reduces loop noise.
[0023] In one embodiment, optionally, the ceramic copper-clad substrate 21 includes an upper copper layer 211, an intermediate ceramic layer 212, and a lower copper layer 213 stacked together; the chip 3 and the thin copper sheet 4 are disposed on the upper surface of the upper copper layer 211, and the upper ends of the chip 3 and the thin copper sheet 4 are exposed on the molding compound 2.
[0024] In some embodiments, the copper layer 6 can be divided into different shapes for circuit connection according to specific circuit needs. The area of the copper layer 6 not covered by the solder mask layer 7 can form a solder pad 8. Copper through holes can be formed in the prepreg layer 5 by drilling and electroplating copper, which are used for electrical connection of chip 3, thin copper sheet 4, copper layer 6, absorption capacitor 9, terminal 10, etc.
[0025] In some application scenarios, the lower copper layer 213 can be directly connected to the heat sink through thermal grease, etc. The heat generated by the capacitor 9, chip 3 and other devices can be conducted to the ceramic copper-clad substrate 21 through the electrical connection structure between PCB layers, and then transferred to the heat sink through the lower copper layer 213 for exhaust. The heat dissipation efficiency is much higher than that of the traditional external suspended arrangement.
[0026] Furthermore, the thickness of the lower copper layer 213 is greater than the thickness of the upper copper layer 211. By designing the ceramic copper-clad substrate 21 as an asymmetrical structure, and only setting the prepreg layer 5 and copper layer 6 on the upper surface of the molding compound 2, that is, by adopting an asymmetrical structure for the PCB board, the asymmetry of the two is offset through reasonable design, so that the overall warpage is within a reasonable range.
[0027] Optionally, the thickness of the lower copper layer 213 is 0.05 mm to 0.3 mm greater than the thickness of the upper copper layer 211. Preferably, the thickness of the lower copper layer 213 is 0.1 mm greater than the thickness of the upper copper layer 211.
[0028] In some embodiments, the absorption capacitor (9) is a surface-mount capacitor. The capacitor can have superior temperature resistance characteristics; for example, a ceramic capacitor can be selected, and its voltage rating, capacitance, and other characteristics can be chosen as needed.
[0029] Furthermore, the pad 8 is also connected to a corresponding terminal 10.
[0030] Accordingly, one embodiment of this application provides a method for fabricating a PCB-packaged power module with an integrated absorption capacitor, comprising the following steps: See Figure 3 A ceramic copper-clad substrate 21 is prepared. The ceramic copper-clad substrate 21 includes an upper copper layer 211, a middle ceramic layer 212, and a lower copper layer 213 stacked together, with the thickness of the lower copper layer 213 greater than the thickness of the upper copper layer 211. Optionally, the thickness of the lower copper layer can be 0.4 mm, the thickness of the upper copper layer can be 0.3 mm, and the middle ceramic layer is made of Si3N4 ceramic with a thickness of 0.32 mm. The upper copper layer 211 is divided into multiple regions according to the circuit topology; among them, a connecting material layer 214 is provided at the position where the chip 3 is to be installed, and a thin copper sheet 4 is provided before and after the chip 3; the connecting material layer 214 can be electroplated silver; the thin copper sheet 4 can be soldered or sintered onto the upper copper layer 211, and the distance from the upper surface of the thin copper sheet 4 to the upper surface of the upper copper layer 211 can be 0.25mm. Of course, in some other embodiments, the position and number of thin copper sheets 4 can be flexibly set as needed.
[0031] See Figure 4 The ceramic copper-clad substrate 21 is encapsulated around and on the top to form a molded body 2; after encapsulation, the lower copper layer 213 is exposed outside the molded body 2, the upper copper layer 211 is completely covered, and the area of the connecting material layer 214 is provided to leave a chip 3 mounting window. See Figure 5A certain thickness is removed from the upper surface of the molding compound 2 by grinding or CNC machining to expose the thin copper sheet 4, and the upper surface of the molding compound 2 is flush with the thin copper sheet 4; at the same time, the thickness from the upper surface of the upper copper layer 211 to the upper surface of the molding compound is slightly greater than the thickness of the chip + connecting material layer 214, and the height difference is controlled within the range of 10-50um to prevent the chip from being directly stressed during subsequent lamination; See Figure 5 After cleaning, the chip 3 is connected to the material layer 214; for example, the chip 3 can be connected to the ceramic copper-clad substrate 21 by welding / sintering, and the height of the upper surface of the chip 3 is 10-50um lower than the height of the upper surface of the molding compound 2. See Figure 6 Prepare a core board 1 with through holes 11. The size of the through holes 11 is slightly larger than the size of the molding compound 2. The gap between the inner wall of the through hole and the outer wall of the molding compound 2 is controlled between 25-100um. The thickness of the core board 1 is the same as the thickness of the molding compound 2, for example, it can be 1.27mm. Embed the molding compound 2 into the core board 1. See Figure 7 and Figure 8 The prepreg layer 5 and the copper layer 6 are pressed onto the core board 1. Holes are drilled at appropriate positions above the chip 3 and the thin copper sheet 4, and then electroplated to fill them, forming an electrical connection. During the pressing process, epoxy resin fills the gap between the core board 1 and the molding compound 2, firmly bonding the two together. See Figure 9 The laminated copper layer 6 is divided into multiple blocks according to functional requirements; it can be divided according to different circuit topologies. Apply a solder resist layer 7 to cover the parts that need to be electrically connected to the outside, and leave solder pads 8 for soldering terminals or other components according to different circuit topologies; Remove core board 1; Weld the connection terminals and absorption capacitor 9 according to different circuit topologies.
[0032] For example, see Figures 10 to 12 In one embodiment, a half-bridge architecture is adopted, and a bus absorption capacitor is introduced, with the absorption capacitor C connected in parallel between the positive and negative terminals.
[0033] In another embodiment, see Figures 13 to 15 It adopts a half-bridge architecture and introduces interstage absorption capacitors. The absorption capacitors C1 and C2 are connected in parallel across the power devices of the upper and lower bridge arms, respectively.
[0034] In this embodiment, preferably, the PCB power module adopts a design structure that can achieve two topologies by modifying the top layer solder mask structure and leaving different soldering areas.
[0035] It should be noted that all the devices (parts whose specific structures are not specified) selected in this application are general standard parts or parts known to those skilled in the art, and their structures and principles can be known to those skilled in the art through technical manuals or conventional experimental methods.
[0036] In the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances.
[0037] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0038] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.
Claims
1. A PCB-packaged power module with an integrated absorption capacitor, characterized in that, include: The molding compound (2) includes a ceramic copper-clad substrate (21) and molding compound (22) encapsulated around and on the top of the ceramic copper-clad substrate (21); a chip (3) and a thin copper sheet (4) are disposed on the upper surface of the ceramic copper-clad substrate (21). A prepreg layer (5) is located above the molding compound (2), and the prepreg layer (5) is provided with copper through holes; The copper layer (6) is located above the prepreg layer (5); Solder mask (7) covers the copper layer (6) and exposes several pads (8). An absorption capacitor (9) is connected to the pad (8).
2. The PCB-packaged power module according to claim 1, characterized in that, The ceramic copper-clad substrate (21) includes an upper copper layer (211), an intermediate ceramic layer (212), and a lower copper layer (213) stacked together. The chip (3) and the thin copper sheet (4) are disposed on the upper surface of the upper copper layer (211), and the upper ends of the chip (3) and the thin copper sheet (4) are exposed to the molding compound (2).
3. The PCB-packaged power module according to claim 2, characterized in that, The lower surface of the lower copper layer (213) is exposed to the molding compound (2).
4. The PCB-packaged power module according to claim 2, characterized in that, The thickness of the lower copper layer (213) is greater than the thickness of the upper copper layer (211).
5. The PCB-packaged power module according to claim 2, characterized in that, The thickness of the lower copper layer (213) is 0.05 mm to 0.3 mm greater than the thickness of the upper copper layer (211).
6. The PCB-packaged power module according to claim 1, characterized in that, The pad (8) is also connected to a corresponding terminal (10).
7. The PCB-packaged power module according to claim 1, characterized in that, The absorption capacitor (9) is a surface-mount capacitor.
8. A method for fabricating a PCB-packaged power module with an integrated absorption capacitor, characterized in that, include: Prepare a ceramic copper-clad substrate (21); the ceramic copper-clad substrate (21) includes an upper copper layer (211), an intermediate ceramic layer (212), and a lower copper layer (213) stacked together, and the thickness of the lower copper layer (213) is greater than the thickness of the upper copper layer (211); The upper copper layer (211) is divided into multiple regions according to the circuit topology; among them, a connection material layer (214) is set at the position to be installed of the chip (3), and several thin copper sheets (4) are set on the outer periphery of the position to be installed of the chip (3). The ceramic copper-clad substrate (21) is encapsulated around and on the top to form a molded body (2); after encapsulation, the lower copper layer (213) is exposed outside the molded body (2), the upper copper layer (211) is completely covered, and the area of the connecting material layer (214) is provided to leave a window for chip (3) installation. Remove a certain thickness from the upper surface of the encapsulated body (2) to expose the thin copper sheet (4); The chip (3) is attached to the bonding material layer (214), and the height of the upper surface of the chip (3) is lower than the height of the upper surface of the molding compound (2); Prepare a core board (1) with a through hole (11), the size of which is larger than the size of the encapsulant (2), and the thickness of the core board (1) is the same as the thickness of the encapsulant (2). Embed the encapsulant (2) into the core board (1). The prepreg layer (5) and copper layer (6) are pressed onto the core board (1), and holes are drilled and electroplated to fill them at appropriate positions above the chip (3) and the thin copper sheet (4) to form an electrical connection. The laminated copper layer (6) is divided into multiple pieces according to functional requirements; Apply a solder resist layer (7) to cover the parts that need to be electrically connected to the outside, leaving the solder pads (8) for soldering terminals or other components. Remove the core board (1); Weld the connection terminal (10) and the absorption capacitor (9).