Power module

Abstract

An embodiment of the present application provides a power module, comprising: a substrate comprising an active surface and a ceramic core; the insulated gate bipolar transistor wafer is arranged on the active surface; an external lead disposed on the active surface and extending in a direction substantially perpendicular to the substrate; and the mold sealing layer covers the substrate and the insulated gate bipolar transistor wafer, and exposes the back surface, opposite to the active surface, of the substrate and the top surface connected with the external lead. According to the invention, vertical lead bonding is carried out by using the external leads, so that the size of the power module is reduced, the back surface, opposite to the active surface, of the substrate is exposed, and the heat dissipation performance of the corresponding power module is further improved.

Description

Technical Field

[0001] This application relates to the field of power device technology, and more specifically, to a power module. Background Technology

[0002] Currently, commercially available Intelligent Power Modules (IPMs) use lead frames as electrical signal pins and are used in products with large size and high current requirements. However, their large size makes miniaturization difficult. Therefore, the design of these products is limited by the lead frame configuration. See details... Figure 1A , Figure 1A The power module 10 of an existing smart power module is shown, such as Figure 1A As shown, in this power module 10, a gate driver integrated circuit 13, such as a thermistor (NTC), is disposed on a printed circuit board (PCB) 11, and a transistor 14, such as an IGBT, is disposed on wiring 17 connected to the PCB 11. The gate driver integrated circuit 13 and the transistor 14 are connected by internal leads 15, such as aluminum. Furthermore, the gate driver integrated circuit 13, transistor 14, wiring 17, and internal leads 15 are molded from a molding compound 12, such as an epoxy molding compound, and led out through a lead frame 16, such as copper. In the power module 10 described above, the lead frame 16 serves as the product's electrical pin.

[0003] To meet the demand for product miniaturization, see [link / reference] Figure 1B , Figure 1B Another power module 10' of the intelligent power module is shown. In this other power module 10', the product's electrical pin design has evolved from the original design using a lead frame 16 to a design using a pin support 17' and a press-fit pin 16'. That is, another type of design utilizing the pin support 17'. However, although there are existing designs using a lead frame 16' with a pin support 17' and a press-fit pin to meet the needs of product miniaturization, the actual product size that can be reduced is limited, and the effect is still limited. Furthermore, Figure 1C It shows Figure 1B The bottom 11A of the substrate 11 of the other power module 10' shown is viewed from below. Figure 1C As can be seen from the view, the bottom 11A of the substrate 11 in the prior art does not have a corresponding patterned design. Figure 1D It shows Figure 1BThe fabrication process of the other power module 10' shown is as follows: In step 10-1, a substrate 11 is placed on a carrier (which may be any suitable carrier); in steps 10-2 and 10-3, a gate driver integrated circuit 13 and a transistor 14, such as a thermistor (NTC), are attached by solder; in step 10-4, the solder is reflowed to bond the gate driver integrated circuit 13 and the transistor 14 to the substrate 11; in step 10-5, the previous carrier is removed and the carrier 11 is placed on another carrier; in steps 10-6 to 10-7, a lead frame 16' is attached and fixed; in steps 10-8 to 10-9, a molding compound 12 is formed and post-cured; in steps 10-10 and 10-12, other external connectors are formed, and the module is thinned by means of a mask, etc., to form the other power module 10'.

[0004] As can be seen, current smart power module products all use the aforementioned lead frame 16 or pin support 17' as the pin design, which limits the size reduction of both electrical pin designs. Therefore, the current smart power module design has the following drawbacks: the product size is limited by the lead frame 16, and the size of the integrated printed circuit board (PCB) 11 cannot be reduced due to the need for interposer design. Therefore, to meet customers' future design requirements for continuously shrinking product sizes, a new solution needs to be proposed. Utility Model Content

[0005] As can be seen from the above problems, there is a need for a power module that meets the requirements of power modules and can reduce size. To solve the above problems, this application provides a technology for vertical lead bonding using external leads such as thicker aluminum wire / thicker copper wire, which can be applied to smart power module products, and further improves the bonding performance of the power module by combining it with a wedge bond.

[0006] Some embodiments of this application provide a power module, including: a substrate including an active surface and a ceramic core; an insulated-gate bipolar transistor (IGBT) chip disposed on the active surface; external leads disposed on the active surface and extending in a direction substantially perpendicular to the substrate; and a molding layer covering the substrate and the IGBT chip, and exposing the back surface of the substrate opposite to the active surface and the top surface of the external leads. In this application, "the external leads are substantially perpendicular to the substrate" means that the external leads form an angle of 90° ± 5° with the plane of the substrate, i.e., an angle of 85° to 95°.

[0007] In some embodiments, the power module further includes an electroplated layer disposed on the back side of the substrate.

[0008] In some embodiments, the electroplated layer has a patterned design to improve the warpage of the substrate.

[0009] In some embodiments, the power module further includes: internal leads connecting the insulated gate bipolar transistor wafer to the active surface of the substrate.

[0010] In some embodiments, the internal lead includes a connection terminal that connects to the active surface, the extension direction of the connection terminal being parallel to the substrate.

[0011] In some embodiments, the power module further includes an external connector disposed on the top surface of the external lead exposed by the molded layer.

[0012] In some embodiments, the drain of the insulated gate bipolar transistor wafer is connected to the active surface.

[0013] In some embodiments, the external lead includes a connection terminal that connects to the active surface, and the extension direction of the connection terminal is parallel to the substrate.

[0014] In some embodiments, the top surface of the external lead is flush with the top surface of the mold sealing layer.

[0015] In some embodiments, the diameter of the outer lead is larger than the diameter of the inner lead.

[0016] In some embodiments, the diameter of the external lead is 15 mil or more.

[0017] In some embodiments, the outermost wall of the molding layer extends beyond the sidewall of the substrate.

[0018] In some embodiments, the gate of the insulated gate bipolar transistor wafer is connected to the internal leads.

[0019] In some embodiments, the source of the insulated gate bipolar transistor wafer faces the active surface of the substrate.

[0020] In some embodiments, the internal leads are spaced apart from the external leads.

[0021] In some embodiments, the electroplated layer may have the same or different density in different regions.

[0022] In some embodiments, the internal leads are electrically connected to the external leads through the active surface of the substrate.

[0023] Other embodiments of this application provide a power module, including: a substrate including an active surface and a ceramic core; an insulated gate bipolar transistor (IGBT) wafer disposed on the active surface; external leads disposed on the active surface and extending in a direction substantially perpendicular to the substrate; and an electroplated layer disposed on the back side of the substrate opposite to the active surface, wherein the electroplated layer has a patterned design. In this application, "external leads substantially perpendicular to the substrate" means that the external leads form an angle of 90° ± 5° with the plane of the substrate, i.e., an angle of 85° to 95°.

[0024] In some embodiments, the power module further includes: a molding layer covering the substrate and the insulated gate bipolar transistor wafer, and exposing the back side of the substrate and the top surface of the external leads.

[0025] In some embodiments, the power module further includes: internal leads connecting the insulated gate bipolar transistor wafer to the active surface of the substrate.

[0026] In summary, this application utilizes thicker aluminum / copper wires of 15 mil or more (such as 15 mil-20 mil) as external leads for electrical pin design, providing thick lines perpendicular to the substrate to connect to the outside, thereby reducing the size of the power module by replacing the lead frame that extends the circuit to the left and right. Furthermore, the external leads further improve the bonding performance of the corresponding power module through a wedge-shaped connection. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figures 1A to 1D A power module in the prior art is shown.

[0029] Figure 2 , Figures 2A to 2E A power module according to some embodiments of this application is shown.

[0030] Figures 3 to 11 The fabrication process of a power module according to some embodiments of this application is illustrated. Detailed Implementation

[0031] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art are within the scope of protection of this application. In addition, when using terms such as "approximately," "about," "substantial," or "basically" to describe numerical values ​​or numerical ranges, unless otherwise stated, the term is intended to cover values ​​within ±10% of the described value. For example, the term "about 5nm" covers a size range from 4.5nm to 5.5nm.

[0032] The following disclosure provides numerous different embodiments or instances for implementing various features of the provided subject matter. Specific examples of elements and arrangements will be described below to simplify the present invention. These are merely examples and are not intended to limit the present invention. For example, in the following description, forming a first component above or on a second component may include embodiments where the first and second components are in direct contact, or embodiments where an additional component is formed between the first and second components such that the first and second components are not in direct contact. Furthermore, reference numerals and / or letters may be repeated in various instances of the present invention. Such repetition is merely for brevity and clarity and does not in itself indicate a relationship between the various embodiments and / or configurations discussed.

[0033] This application utilizes the concept of vertical lead bonding in power modules, such as in SiP (silicon-in-package) semiconductor packaging technology. It achieves the goal of replacing the lead frame by using wedge bonding and external leads of 15 mil or more thick aluminum / copper wires as electrical pins. Specifically, this application reduces the size of the power module by using external leads for vertical lead bonding and further improves the heat dissipation performance of the corresponding power module by exposing the back side of the substrate opposite the active surface.

[0034] See Figure 2This application provides a power module 100, including: a substrate 101, including an active surface 101s and a ceramic core 101A; an insulated gate bipolar transistor (IGBT) wafer 104 disposed on the active surface 101s; and an external lead 106 disposed on the active surface 101s and extending in a direction substantially perpendicular to the substrate 101. In some embodiments, the external lead 106 being substantially perpendicular to the substrate 101 means that the external lead 106 forms an angle of 90°±5° with the plane containing the substrate 101, i.e., an angle of 85° to 95°. In some embodiments, the power module 100 further includes a molding layer 102 covering the substrate 101 and the IGBT wafer 104, and exposing the back surface 101d of the substrate 101 opposite to the active surface 101s and the top surface 106t of the external lead 106. Furthermore, in this application, the power module 100 also includes an electroplated layer 107 disposed on the back surface 101d of the substrate 101. In some embodiments, the outermost wall 102o of the molding layer 102 extends beyond the sidewall 101o of the substrate 101. In this application, the substrate 101 is a ceramic copper-clad (DBC) substrate and includes a ceramic core 101A and copper-plated layers 107 and wiring layers 108 disposed on both sides of the ceramic core 101A. That is, the interior is a ceramic core, and the back surface 101d of the substrate 101 is exposed, which can increase the heat dissipation capacity of the power module 100. In some embodiments, the electroplated layer 107 and wiring layer 108 are respectively connected to the ceramic core 101A via a seed layer 101B. In some embodiments, the electroplated layer 107 and wiring layer 108 may be made of copper, and the seed layer 101B may be a metal including but not limited to copper, gold, silver, etc. In some embodiments, the substrate 101 may be a printed circuit board (PCB). In some embodiments, the external leads 106 may be made of a metal such as copper or aluminum. In some embodiments, the molding layer 102 includes, but is not limited to, molding compounds such as molding compounds.

[0035] Figure 2A and Figure 2B It shows Figure 2 The power module 100 is shown in a top-down view. Figure 2A and Figure 2B As shown, the electroplated layer 107 has a patterned design to improve the warpage of the substrate 101. Further, in some embodiments, the density of the electroplated layer 107 may be the same or different in different regions, which can be adjusted according to the actual situation of the power module 100, thereby further adjusting or reducing the warpage of the power module 100. Specifically, the electroplated layer 107 may have the following characteristics: Figure 2A The uniform shape shown can also have, for example, the shape of the uniform shape shown. Figure 2B The uneven shape shown should be understood. Figure 2A and Figure 2BThe patterns shown are for illustrative purposes only, and the electroplated layer 107 can have any suitable shape. In some embodiments, the distribution of the pattern of the electroplated layer 107 can affect its corresponding patterning density, thereby reducing the warpage of the substrate 101 and thus reducing the impact of warpage on the power module 100. Therefore, in this application, the exposed circuit layer 107 on the back side 101b of the substrate 101 can not only be used for heat dissipation but can also be patterned to reduce the impact of warpage.

[0036] In addition, see Figure 2 The power module 100 further includes an internal lead 105 connecting the insulated gate bipolar transistor (IGBT) wafer 104 to the active surface 101s of the substrate 101. Specifically, the internal lead 105 connects the pad 104p on the IGBT wafer 104 to the pad 108P on the active surface 101s of the substrate 101. Further, the pad 108P is disposed on the wiring layer 108 at the active surface 101s of the substrate 101. In some embodiments, the drain D of the IGBT wafer 104 is connected to the active surface 101s, i.e., through the internal lead 105. In some embodiments, the gate G of the IGBT wafer 104 is connected to the internal lead 105 and to a first active or passive device 103. In some embodiments, the first active or passive device 103 may be a diode, a control integrated circuit (IC), or any other suitable device. In some embodiments, the source S of the IGBT wafer 104 faces the active surface 101s of the substrate 101. Figure 2 As shown, the internal lead 105 is spaced apart from the external lead 106. In some embodiments, the internal lead 105 and the external lead 106 are electrically connected through the active surface 101s of the substrate 101. Further, they can be electrically connected through the wiring layer 108 at the active surface 101s. In some embodiments, a second active or passive device 113 is further disposed on the substrate 101. In some embodiments, the second active or passive device 113 includes, but is not limited to, a thermistor (NTC). In a further embodiment, the insulated gate bipolar transistor chip 104, the first active or passive device 103, and the second active or passive device 113 are all connected to the active surface 101s of the substrate 101 via solder 110. In some embodiments, the internal lead 105 may be made of a metal such as aluminum. In some embodiments, the pads 104p and 108P may include, but are not limited to, metals or metal alloys, such as copper, gold, silver, etc.

[0037] Next, see Figure 2C , Figure 2C An enlarged view of the internal lead 105 is shown, and only the internal lead 105 of the substrate 101 is shown; other components are omitted for ease of understanding. From Figure 2CAs can be seen, the internal lead 105 includes a connection end 105d that connects to the active surface 101s, from... Figure 2C As can be seen, the extension direction of the connection end 105d is parallel to the substrate 101. In some embodiments, the extension direction of the connection end 105d can be substantially parallel to the substrate 101. That is, the angle between the extension direction of the connection end 105d and the surface of the substrate 101 can be within ±5°. Thus, the internal lead 105 forms a J-shaped end feature, thereby forming a wedge-shaped engagement of the internal lead 105.

[0038] Further, see Figure 2 The power module 100 also includes an external connector 109 disposed on the top surface 106t of the external lead 106 exposed by the molding layer 102. In some embodiments, the top surface 102t of the molding layer 102 is flush with the top surface 106t of the external lead 106. In some embodiments, the external connector 109 may include, but is not limited to, microbumps or solder balls made of solder paste.

[0039] See Figure 2D , Figure 2D Shown Figure 2 An enlarged view of region A of the power module 100 shown. (See attached image.) Figure 2D As shown, the external lead 106 includes a connection end 106d that connects to the active surface 101s. The extension direction of the connection end 106d is parallel to the substrate 101. In some embodiments, the extension direction of the connection end 106d can be substantially parallel to the substrate 101. That is, the angle between the extension direction of the connection end 106d and the surface of the substrate 101 can be within ±5°, thereby forming a J-shaped end feature of the external lead 106, thus forming a wedge-shaped connection of the external lead 106.

[0040] Reference Figure 2 as well as Figure 2E , Figure 2E An enlarged view of the external lead 106 is shown, as follows. Figure 2E As shown, the diameter d of the external lead 106 is larger than the diameter of the internal lead 105. In some embodiments, the diameter d of the external lead 106 is 15 mil or more, and in some embodiments, it is in the range of 15 mil to 20 mil. As is known to those skilled in the art, an external lead 106 with a diameter d of 20 mil can be used for a current intensity of 70A. In this application, a thicker circuit can be made using a wedge joint, and a J-shaped end feature can be made at the connection end (wire bonding end) 106d.

[0041] In summary, in the power module 100 provided in this application, a vertical circuit is made using external leads 106 and exposed on the top surface 102t of the molded layer 102. A thicker line (15mil or more, such as 15mil-20mil) suitable for the power module 100 is made by wedge joint, and electrical connections are made vertically upward using this thick line, thereby reducing the volume of the power module 100.

[0042] Some embodiments of this application also provide a power module 100, such as Figures 2 to 2B As shown, the power module 100 includes: a substrate 101, including an active surface 101s and a ceramic core 101A; an insulated gate bipolar transistor (IGBT) chip 104 disposed on the active surface 101s; an external lead 106 disposed on the active surface 101s and extending in a direction substantially perpendicular to the substrate 101; and an electroplated layer 107 disposed on the back surface 101b of the substrate 101 opposite to the active surface 101s, wherein the electroplated layer 107 has such Figure 2A and Figure 2B The patterned design is shown. In some embodiments, the power module 100 further includes a molding layer 102 that covers the substrate 101 and the insulated gate bipolar transistor (IGBT) wafer 104, and exposes the back surface 101b of the substrate 101 and the top surface 106t of the external leads 106. In a further embodiment, the power module 100 also includes internal leads 105 that connect the IGBT wafer 104 and the active surface 101s of the substrate 101.

[0043] In summary, this application utilizes the concept of vertical lead bonding in power modules and employs 15mil-20mil external bonding wires as electrical pin designs, thereby replacing the lead frame in the prior art. Furthermore, in this application, the product size of the power module can be reduced through the vertical lead bonding design, and the heat dissipation area at the back surface 101b of the exposed substrate 101 can be increased by exposing the electroplated layer 107 on the back surface 101b of the substrate 101.

[0044] Therefore, the concept of vertical lead bonding allows for novel I / O applications using vertical leads. Furthermore, by eliminating the lead frame design, the first active or passive device 103 and the second active or passive device 113, along with components such as a control IC and RLC (resistors, inductors, or capacitors), can be integrated onto the same substrate 101. This reduces the lead frame size while increasing the area of ​​the substrate 101, simultaneously expanding the heat dissipation area of ​​the electroplated layer 107 on the substrate 101 and improving heat dissipation efficiency. Currently, there are no products on the market with this power module design structure. Moreover, this power module design can reduce the size of IPM products, improve production efficiency, and achieve the benefit of reducing the design size of the system substrate 101, making it applicable to power module products with related lead frame designs.

[0045] Next, refer to Figures 3 to 11 To describe Figure 2 The manufacturing process of the power module 100 shown. Specifically, Figure 3 A process flow diagram for forming the power module 100 is shown. Figures 4 to 5 A cross-sectional view of the corresponding power module 100 is shown.

[0046] See Figures 3 to 4 In step 201, substrate 101 is provided or placed on a carrier (not shown). In some embodiments, the carrier can be any suitable carrier, and substrate 101 can be a ceramic copper-clad substrate, such as... Figure 4 As shown, the substrate 101 includes a ceramic core 101A and electroplated layers 107 and wiring layers 108 disposed on opposite sides of the ceramic core 101A. Specifically, the electroplated layers 107 and wiring layers 108 may be made of copper and are respectively connected to the ceramic core 101A through corresponding seed layers 101B (which may be made of copper). Then, in steps 202-203, an insulated gate bipolar transistor wafer 104, a first active or passive device 103, and a second active or passive device 113 are attached to the active surface 101s of the substrate 101 using solder 110. In some embodiments, the first active or passive device 103 is a diode, and the second active or passive device 113 is a thermistor. Subsequently, in step 204, the insulated gate bipolar transistor wafer 104, the first active or passive device 103 and the second active or passive device 113 are bonded to the wiring layer 108 of the substrate 101 or the pad 108P on the wiring layer 108 by reflow solder 110.

[0047] See afterward. Figure 3 and Figure 5In steps 205-1 and 105-2, the internal lead 105 and the external lead 106 are formed by a wedge-shaped connection. The following will use the internal lead 105 as an example. Figures 6 to 11 To describe the wedge-shaped engagement of the internal lead 105.

[0048] See Figure 6 A metal wire 1002, such as aluminum, is pressed onto the active surface 101s of the substrate 101 using a clamp 1001 (or it may be an insulated gate bipolar transistor wafer 104, a first active or passive device 103, and a second active or passive device 113). Then, see [link to relevant documentation]. Figure 7 One end of the metal wire 1002 is bonded to the active surface 101s of the substrate 101 by ultrasonic energy 1003.

[0049] After one end of the metal wire 1002 is bonded to the active surface 101s of the substrate 101, see Figure 8 The metal wire 1002 is raised using the clamp 1001 so that it rises in an arc to the desired height. See also Figure 9 The metal wire 1002 is pulled directly along an arc to a certain height, thus forming the desired arc. Then, see... Figure 10 The other end of the metal wire 1002 is bonded to the active surface 101s of the substrate 101 by ultrasonic energy 1004, thereby creating a second bonding. Finally, the unbonded portion of the metal wire 1002 is removed to form an internal lead 105, which has a connection end 105d and the extension direction of the connection end 105d is parallel to the substrate 101.

[0050] Similarly, for the external lead 106, and... Figures 6 to 11 The steps shown are the same, the difference is in Figure 9 In the pull-up process shown, a thicker metal wire, such as copper or aluminum, is pulled vertically upwards to form the external lead 106, which will not be described again here.

[0051] Continue to refer to Figure 3 In step 206, a molding seal layer 102 is formed using a molding process, such as compression molding or transfer molding, using a molding compound to form the molding seal layer 102. In subsequent step 207, the molding seal layer 102 is cured using a post-curing molding compound. Next, in step 208, a portion of the molding seal layer 102 is removed using a grinding process, thereby making the top surface 102t of the molding seal layer 102 flush with the top surface 106t of the external lead 106.

[0052] Finally, refer to Figure 3Steps 209 and 210 form a mask layer exposing the top surface 106t of the external lead 106, and the external connector 109, such as a solder ball, is formed through the pre-soldering process in step 210, thereby forming... Figure 2 The power module 100 shown.

[0053] In summary, the power module 100 provided in this application has the following advantages:

[0054] (1) The power module 100 is reduced in size by using a wedge joint and replacing the input / output pins of the lead frame with thicker external leads 106 (diameter d > 15 mil) such as copper or aluminum wires.

[0055] (2) The package size of the power module 100 has been reduced; and

[0056] (3) The increased exposed area of ​​the electroplated layer 107 on the back side 101b of the substrate 101 (increased exposed copper) can enhance the heat dissipation capability of the power module, and the patterned design can further reduce the warpage of the power module 100.

[0057] Therefore, the power module 100 produced by the method of this application reduces the size of the product and achieves SMD (surface mount device) design by using substantially vertical external leads 106 to replace the original lead frame pin design, thereby increasing the output of the power module 100.

[0058] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A power module, comprising: The substrate includes the active surface and the ceramic core; An insulated gate bipolar transistor wafer is disposed on the active surface; External leads are provided on the active surface and extend in a direction perpendicular to the substrate; as well as A molding layer covers the substrate and the insulated gate bipolar transistor wafer, and exposes the back side of the substrate opposite to the active surface and the top surface of the external leads.

2. The power module according to claim 1, further comprising: An electroplated layer is disposed on the back side of the substrate.

3. The power module according to claim 2, wherein, The electroplated layer has a patterned design to improve the warpage of the substrate.

4. The power module according to claim 1, further comprising: Internal leads connect the insulated gate bipolar transistor wafer to the active surface of the substrate.

5. The power module according to claim 4, wherein, The internal lead includes a connection terminal that connects to the active surface, and the extension direction of the connection terminal is parallel to the substrate.

6. The power module according to claim 1, further comprising: An external connector is provided on the top surface of the external lead exposed by the molded layer.

7. The power module according to claim 1, wherein, The external lead includes a connection terminal that connects to the active surface, and the extension direction of the connection terminal is parallel to the substrate.

8. The power module according to claim 1, wherein, The top surface of the external lead wire is flush with the top surface of the mold sealing layer.

9. The power module according to claim 4, wherein, The diameter of the outer lead is larger than the diameter of the inner lead.

10. The power module according to claim 1, wherein, The outermost wall of the molding layer extends beyond the sidewall of the substrate.

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