A trench insulated gate bipolar transistor package structure and a manufacturing method thereof

Abstract

The application relates to the field of transistor packaging technology and discloses a trench type insulated gate bipolar transistor packaging structure and a manufacturing method thereof. The trench type insulated gate bipolar transistor packaging structure comprises a trench type insulated gate bipolar transistor, a lead frame, a first solder wire connecting an emitter metal layer and an emitter pin, and the like. The trench type insulated gate bipolar transistor comprises an emitter metal layer electrically connected with an emitter and a trench type gate located at one side of the emitter metal layer. The lead frame comprises a chip placement area for fixing the trench type insulated gate bipolar transistor and an emitter lead-out end. One end of the first solder wire is connected with the surface of the emitter metal layer away from the trench type gate to form a strip-shaped first solder joint, the other end of the first solder wire is connected with the emitter lead-out end to form a second solder joint, and the extension direction of the first solder joint is perpendicular to the extension direction of the trench of the trench type gate. The packaging structure reduces the stress of a single trench, improves the solder wire yield, and improves the reliability of the chip.

Description

Technical Field

[0001] The present invention relates to the technical field of transistor packaging, and in particular to a trench-type insulated gate bipolar transistor packaging structure and a manufacturing method thereof. Background Art

[0002] Insulated Gate Bipolar Transistors (IGBTs) are primarily used in AC motors for variable-frequency air conditioners, inverters, switching power supplies, lighting circuits, and traction drives. Because IGBTs are essentially circuit switches, they operate in high-voltage applications with voltages ranging from hundreds to thousands of volts and currents ranging from tens to hundreds of amperes. Therefore, their reliability requirements are much higher than those of standard consumer electronics.

[0003] There are two types of IGBT process technologies: planar and trench. Trench is a newer technology that increases cell density without compromising other electrical properties, significantly reducing conduction losses. Consequently, trench IGBTs are thinner, have higher current density, and are lower cost than planar IGBTs.

[0004] Trench IGBTs, however, are prone to experiencing a sharp increase in leakage current during reliability verification, leading to chip burnout. This is primarily due to process weaknesses on the chip surface or within certain internal areas. Methods for optimizing the reliability of trench IGBTs include: 1. Improving the chip structure; 2. Improving the packaging stage. Regarding the overall design of an IGBT device, once the specific chip parameters have been confirmed, improving chip reliability through respins is essentially impossible (due to the long and costly tapeout cycles). Therefore, the fastest, most cost-effective, and most effective method is to improve the reliability of the entire device through the chip packaging method.

[0005] Currently, there is no mature packaging technology for thin trench IGBTs in China. The wire bonding process only coordinates three parameters, power, force, and time, to improve wire bond reliability. The first solder joint connecting the wire to the chip is not controlled, resulting in a very small number of grooves below the first solder joint. This results in a small number of grooves being subjected to high compressive stress during welding, leading to damage. Summary of the Invention

[0006] The present invention provides a trench-type insulated gate bipolar transistor packaging structure and a manufacturing method thereof. In the above-mentioned trench-type insulated gate bipolar transistor packaging structure, the first bonding wire pressure is evenly distributed on a large number of gate trenches, thereby reducing the stress of a single trench, improving the bonding wire yield, and thus improving the reliability of the entire chip.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A trench-type insulated gate bipolar transistor packaging structure, comprising:

[0009] A trench-type insulated gate bipolar transistor, comprising an emitter metal layer electrically connected to an emitter and a trench-type gate located on one side of the emitter metal layer;

[0010] A lead frame, the lead frame comprising a chip placement area and an emitter lead end for fixing the trench insulated gate bipolar transistor;

[0011] A first welding wire is connected to the emitter metal layer and the emitter pin, one end of the first welding wire is connected to the surface of the emitter metal layer away from the trench gate to form a first strip-shaped welding point, and the other end is connected to the emitter lead end to form a second welding point, and the extension direction of the first welding point is perpendicular to the extension direction of the trench gate trench.

[0012] The trench-type insulated gate bipolar transistor package structure includes a trench-type insulated gate bipolar transistor, a lead frame, and a first bonding wire electrically connecting the trench-type insulated gate bipolar transistor and the lead frame. The trench-type insulated gate bipolar transistor has an emitter metal layer electrically connected to the emitter and a trench-type gate located on one side of the emitter metal layer. The lead frame has a chip placement area for fixing the trench-type insulated gate bipolar transistor and an emitter terminal. The trench-type insulated gate bipolar transistor is fixed to the chip placement area, and the emitter metal layer is electrically connected to the emitter terminal via the first bonding wire. The direction of the first strip-shaped bonding point connecting the first bonding wire to the emitter metal layer is perpendicular to the direction of the trench-type gate trench. Since the direction of the first strip-shaped bonding point is perpendicular to the direction of the trench of the trench gate, the first bonding point can press against more gate trenches, allowing more gate trenches to share the pressure of the first bonding point, reducing the stress of a single trench, avoiding chip damage during welding, improving the bonding wire yield, and thereby improving the reliability of the entire chip.

[0013] Preferably, a portion of the first bonding wire located between the first bonding point and the second bonding point forms an arc portion, and the arc height of the highest point of the arc portion from the emitter metal layer is 750 microns to 1000 microns.

[0014] Preferably, the emitter lead-out terminal has a first wire pad for connecting to the first bonding wire, and the second welding point is formed on the first wire pad.

[0015] Preferably, at least one first bonding wire is connected between the emitter metal layer and the first wire pad.

[0016] Preferably, the lead frame further includes a gate lead-out terminal, and the trench gate is electrically connected to the gate lead-out terminal via a second bonding wire.

[0017] Preferably, the trench insulated gate bipolar transistor includes a silicon substrate, the trench gate formed on the silicon substrate, a silicon oxide insulating layer formed on the surface of the trench gate, and the emitter metal layer formed on the side of the silicon oxide insulating layer away from the silicon substrate.

[0018] Preferably, the trench insulated gate bipolar transistor further comprises a collector located on the side of the silicon substrate away from the trench gate, the lead frame further comprises a collector lead end, and the collector is electrically and physically connected to the chip placement area of ​​the lead frame through a bonding material.

[0019] Preferably, it also includes a plastic-encapsulated shell with a completely filled interior formed by a plastic-encapsulation process.

[0020] The present invention also provides a method for manufacturing the trench-type insulated gate bipolar transistor package structure provided by any of the above technical solutions, comprising:

[0021] Fixing the trench insulated gate bipolar transistor to the chip placement area of ​​the lead frame;

[0022] Using an ultrasonic welding blade to press-weld one end of a first welding wire to the emitter metal layer of the trench-type insulated gate bipolar transistor to form a first strip-shaped welding point extending in a direction perpendicular to the extending direction of the trench-type gate trench;

[0023] Lifting the ultrasonic welding blade vertically and holding it there for a predetermined time to allow the first welding line to generate an arc with a predetermined height;

[0024] The ultrasonic welding blade is jumped to the emitter lead-out end of the lead frame for pressure welding, so that the first welding wire is connected to the emitter lead-out end and a second welding point is formed.

[0025] In the above-mentioned manufacturing method of the trench-type insulated gate bipolar transistor packaging structure, an ultrasonic welding chopper is used to press weld to form a first strip-shaped weld perpendicular to the extension direction of the trench-type gate trench. After the first weld is completed, the ultrasonic welding chopper is vertically lifted to form an arc height of a set height, and then the ultrasonic chopper is adjusted to the emitter lead end of the lead frame to press weld a second weld, completing the welding pressure of the first weld wire. In the above-mentioned manufacturing method, since the strip-shaped first weld is set perpendicular to the groove of the trench-type gate, the first weld can be pressed to more gate trenches, so that more gate trenches share the pressure of the first weld, reducing the stress of a single groove, avoiding chip damage during welding, improving the weld wire yield, and thereby improving the reliability of the entire chip.

[0026] Preferably, the preset time is 1 millisecond to 10 milliseconds.

[0027] Preferably, the arc height of the first welding line setting height is 750 microns to 1000 microns.

[0028] Preferably, after completing the electrical connection between the trench-type insulated gate bipolar transistor chip and the corresponding pins on the lead frame, the combined device of the trench-type insulated gate bipolar transistor chip and the lead frame is filled with plastic packaging material to form a completely filled plastic package shell. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic structural diagram of a trench insulated gate bipolar transistor provided by an embodiment of the present invention;

[0030] Figure 2 A schematic structural diagram of a trench gate provided by an embodiment of the present invention;

[0031] Figure 3 A schematic structural diagram of a trench insulated gate bipolar transistor packaging structure provided by an embodiment of the present invention;

[0032] Figure 4 for Figure 3 A top view of the structural diagram;

[0033] Figure 5 A flow chart of a method for manufacturing a trench insulated gate bipolar transistor packaging structure provided by an embodiment of the present invention.

[0034] icon:

[0035] 1- Trench insulated gate bipolar transistor; 11- Silicon substrate; 12- Trench gate; 13- Silicon oxide insulating layer; 14- Emitter metal layer; 2- Lead frame; 21- Chip placement area; 22- First wire pad; 23- Second wire pad; 24- Collector terminal; 3- First bonding wire; 31- First solder joint; 32- Second solder joint; 33- Arc portion; 4- Bonding material. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] Please refer to Figures 1 to 3 The present invention provides a trench-type insulated gate bipolar transistor packaging structure, comprising:

[0038] A trench-type insulated gate bipolar transistor 1 includes an emitter metal layer 14 electrically connected to an emitter and a trench-type gate 12 located on one side of the emitter metal layer 14;

[0039] A lead frame 2, the lead frame 2 including a chip placement area 21 for fixing the trench insulated gate bipolar transistor 1 and an emitter lead end;

[0040] A first welding wire 3 is connected between the emitter metal layer 14 and the emitter pin, one end of the first welding wire 3 is connected to the surface of the emitter metal layer 14 facing away from the trench gate 12 to form a strip-shaped first welding point 31, and the other end is connected to the emitter lead end to form a second welding point 32, and the extension direction of the first welding point 31 is perpendicular to the extension direction of the trench of the trench gate 12.

[0041] The above-mentioned embodiment of the invention provides a trench-type insulated gate bipolar transistor packaging structure, comprising a trench-type insulated gate bipolar transistor 1, a lead frame 2, and a first bonding wire 3 electrically connecting the trench-type insulated gate bipolar transistor 1 and the lead frame 2. The trench-type insulated gate bipolar transistor 1 has an emitter metal layer 14 electrically connected to the emitter and a trench-type gate 12 located on one side of the emitter metal layer 14. The lead frame 2 has a chip placement area 21 for fixing the trench-type insulated gate bipolar transistor 1 and an emitter lead terminal. The trench-type insulated gate bipolar transistor 1 is fixed to the chip placement area 21. 1. The emitter metal layer 14 is electrically connected to the emitter lead terminal through the first bonding wire 3. The extension direction of the first strip-shaped first bonding point 31 connecting the first bonding wire 3 to the emitter metal layer 14 is perpendicular to the extension direction of the trench of the trench-type gate 12. Since the extension direction of the strip-shaped first bonding point 31 is perpendicular to the extension direction of the trench on the trench-type gate 12, the first bonding point 31 can press on more gate trenches, allowing more gate trenches to share the pressure of the first bonding point 31, reducing the stress of a single trench, avoiding chip damage during bonding, improving the bonding wire yield, and thereby improving the reliability of the entire chip.

[0042] In the above-mentioned embodiments of the invention, specifically, Figure 3 As shown, the portion of the first bonding wire 3 located between the first bonding point 31 and the second bonding point 32 forms an arc-shaped portion 33. The highest point of the arc-shaped portion 33 has an arc height of 750 to 1000 microns from the emitter metal layer 14. This arc-shaped portion 33 has a higher arc height than conventional bonding wires, which evenly distributes the bonding wire pressure across a larger number of grooves, further balancing the forces applied to each groove, preventing chip damage during bonding, and improving the bonding wire yield. Furthermore, because the arc-shaped portion 33 of the first bonding wire 3 is raised, the distance between the first bonding wire 3 and the chip is increased, facilitating complete filling of the molding compound during chip encapsulation, improving the bonding wire yield, and enhancing the overall reliability of the device.

[0043] In the above-mentioned embodiment of the invention, Figure 4 As shown, the emitter lead-out terminal has a first wire pad 22 for connecting to the first bonding wire 3, and a second welding point 32 is formed on the first wire pad 22, thereby achieving electrical connection between the emitter metal layer 14 and the emitter lead-out terminal.

[0044] In the above-described embodiment of the invention, at least one first bonding wire 3 is connected between the emitter metal layer 14 and the first bonding pad 22. For example, if a 20-mil first bonding wire 3 is required, two 10-mil first bonding wires 3 can be bonded to the same bonding pad to achieve the same current level. Bonding two first bonding wires 3 can increase the contact area between the first bonding point 31 and the emitter metal layer 14, thereby reducing the impact of welding stress on the chip. In actual applications, the number of first bonding wires 3 and first bonding pads 22 is selected based on actual conditions and is not limited here. For example, there can be one or more first bonding pads 22. When there are multiple first bonding pads 22, the multiple first bonding wires 3 are connected to the multiple first bonding pads 22.

[0045] In the above-mentioned embodiment of the invention, Figure 4 As shown, the lead frame 2 further includes a gate lead terminal, and the trench gate 12 is electrically connected to the gate lead terminal via a second bonding wire. Specifically, the gate lead terminal has a second wire pad 23 for electrically connecting to the second bonding wire.

[0046] In the above-mentioned embodiments of the invention, specifically, Figure 1 As shown, the trench insulated gate bipolar transistor 1 includes a silicon substrate 11, a trench gate 12 formed on the silicon substrate 11, a silicon oxide insulating layer 13 formed on the surface of the trench gate 12, and an emitter metal layer 14 formed on the side of the silicon oxide insulating layer 13 away from the silicon substrate 11.

[0047] In the above-described embodiment of the invention, the trench insulated gate bipolar transistor 1 further includes a collector located on the side of the silicon substrate 11 facing away from the trench gate 12, and the lead frame 2 further includes a collector lead terminal 24. The collector is electrically and physically connected to the chip placement area 21 of the lead frame 2 via a bonding material 4. Optionally, the bonding material 4 may be a conductive adhesive to achieve electrical connection between the collector and the lead frame 2. The bonding material 4 may also be other materials capable of achieving electrical and physical connection between the collector and the chip placement area 21 of the lead frame 2, and is not limited herein.

[0048] It should be noted that the position arrangement of the wire pads on the lead frame 2 may vary according to the actual production design, and is not limited to Figure 4 The structure shown in .

[0049] The above-mentioned embodiment of the invention further includes a completely filled plastic-encapsulated shell formed by a plastic encapsulation process, which can ensure that there are no voids inside the plastic-encapsulated device, improve the welding yield of the bonding wires, and improve the overall reliability of the device.

[0050] In the above-mentioned embodiment of the invention, the first bonding wire 3 is a metal conductor, such as an aluminum wire or a copper wire, which can save manufacturing costs.

[0051] The present invention also provides a method for manufacturing the trench-type insulated gate bipolar transistor packaging structure provided in any of the above embodiments, such as Figure 5 As shown, the following steps are included:

[0052] S501: fixing the trench insulated gate bipolar transistor to the chip placement area of ​​the lead frame;

[0053] S502: Using an ultrasonic welding blade to press-weld one end of a first bonding wire to the emitter metal layer of the trench-type insulated gate bipolar transistor to form a first strip-shaped welding spot extending in a direction perpendicular to the extending direction of the trench-type gate trench;

[0054] S503: lifting the ultrasonic welding blade vertically and holding it for a predetermined time so that the first welding line generates an arc height of a predetermined height;

[0055] S504: Jump the ultrasonic welding blade to the emitter lead-out terminal of the lead frame for pressure welding, so that the first welding wire is connected to the emitter lead-out terminal and a second welding point is formed.

[0056] In the manufacturing method of the trench-type insulated gate bipolar transistor packaging structure provided by the above-mentioned embodiment of the invention, an ultrasonic welding chopper is used to press and weld to form a first strip-shaped weld perpendicular to the extension direction of the trench-type gate groove. After the first weld is completed, the ultrasonic welding chopper is vertically lifted to form an arc height of a set height, and then the ultrasonic chopper is adjusted to the emitter lead end of the lead frame to press and weld a second weld, completing the welding pressure of the first welding wire. In the above-mentioned manufacturing method, since the strip-shaped first weld is set perpendicular to the groove of the trench-type gate, the first weld can be pressed to more gate grooves, so that more gate grooves share the pressure of the first weld, reducing the stress of a single groove, avoiding chip damage during welding, improving the welding wire yield, and thereby improving the reliability of the entire chip.

[0057] The principle of the ultrasonic welding is as follows: applying a certain pressure in the vertical direction and a certain vibration frequency in the plane direction of the chip so that the metal layer above the chip is combined with the welding wire to form a first welding point.

[0058] In the above-mentioned embodiment of the invention, according to the specific conditions of industrial production, in order to improve the utilization rate of time, the preset time can be set to 1 millisecond to 10 milliseconds.

[0059] In the above-described embodiment of the invention, the arc height of the first bonding wire can be set to 750 to 1000 microns. This arc height range is higher than that of conventional bonding wires, evenly distributing the bonding wire pressure across a larger number of grooves, further balancing the forces acting on each groove, preventing chip damage during bonding, and improving the bonding wire yield. Furthermore, because the arc portion 33 of the first bonding wire 3 is raised, the distance between the first bonding wire 3 and the chip is increased, facilitating complete filling of the molding compound during chip encapsulation, improving the bonding wire yield, and enhancing the overall reliability of the device.

[0060] In the above-described embodiment of the invention, after the trench-type insulated gate bipolar transistor chip is electrically connected to the corresponding pins on the lead frame, the combined trench-type insulated gate bipolar transistor chip and lead frame is filled with a plastic encapsulation compound to form a completely filled plastic encapsulation housing. This ensures that the interior of the plastic encapsulated device is completely filled without leaving any voids, thereby improving the soldering yield of the bonding wires and enhancing the overall reliability of the device. Preferably, the plastic encapsulation compound is filled along the mold flow direction, that is, during the plastic encapsulation process, the molten plastic encapsulation compound is poured into the product through the injection port of the plastic encapsulation mold.

[0061] Obviously, those skilled in the art may make various changes and modifications to the embodiments of the present invention without departing from the spirit and scope of the present invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims and their equivalents, the present invention is intended to include such modifications and variations.

Claims

1. A trench-type insulated gate bipolar transistor package structure, characterized in that: include: A trench-type insulated gate bipolar transistor, comprising an emitter metal layer electrically connected to an emitter and a trench-type gate located on one side of the emitter metal layer; A lead frame, the lead frame comprising a chip placement area and an emitter lead end for fixing the trench insulated gate bipolar transistor; a first bonding wire connecting the emitter metal layer and the emitter lead terminal, wherein one end of the first bonding wire is connected to a surface of the emitter metal layer facing away from the trench gate to form a first strip-shaped bonding point, and the other end is connected to the emitter lead terminal to form a second bonding point, and an extension direction of the first bonding point is perpendicular to an extension direction of the trench gate trench; A portion of the first bonding wire located between the first bonding point and the second bonding point forms an arc portion, and a height of the arc portion from the highest point of the arc portion to the emitter metal layer is 750 micrometers to 1000 micrometers.

2. The trench insulated gate bipolar transistor package structure according to claim 1, wherein: The emitter lead-out terminal has a first wire pad for connecting with the first bonding wire, and the second bonding point is formed on the first wire pad.

3. The trench-type insulated gate bipolar transistor package structure according to claim 2, wherein: At least one first bonding wire is connected between the emitter metal layer and the first wire pad.

4. The trench insulated gate bipolar transistor package structure according to claim 1, wherein: The lead frame further includes a gate lead-out terminal, and the trench gate is electrically connected to the gate lead-out terminal through a second bonding wire.

5. The trench-type insulated gate bipolar transistor package structure according to claim 1, wherein: The trench insulated gate bipolar transistor includes a silicon substrate, the trench gate formed on the silicon substrate, a silicon oxide insulating layer formed on the surface of the trench gate, and the emitter metal layer formed on a side of the silicon oxide insulating layer away from the silicon substrate.

6. The trench-type insulated gate bipolar transistor package structure according to claim 5, wherein: The trench insulated gate bipolar transistor further includes a collector located on a side of the silicon substrate away from the trench gate, and the lead frame further includes a collector lead end. The collector is electrically and physically connected to the chip placement area of ​​the lead frame through a bonding material.

7. The trench-type insulated gate bipolar transistor package structure according to claim 1, wherein: Also included is a fully filled plastic shell formed by a plastic encapsulation process.

8. A method for manufacturing a trench-type insulated gate bipolar transistor package structure according to any one of claims 1 to 7, characterized in that: include: Fixing the trench insulated gate bipolar transistor to the chip placement area of ​​the lead frame; Using an ultrasonic welding blade to press-weld one end of a first welding wire to the emitter metal layer of the trench-type insulated gate bipolar transistor to form a first strip-shaped welding point extending in a direction perpendicular to the extending direction of the trench-type gate trench; Lifting the ultrasonic welding blade vertically and holding it for a predetermined time to allow the first weld line to generate an arc height of a predetermined height; the arc height of the first weld line being predetermined is 750 micrometers to 1000 micrometers; The ultrasonic welding blade is jumped to the emitter lead-out end of the lead frame for pressure welding, so that the first welding wire is connected to the emitter lead-out end and a second welding point is formed.

9. The method for manufacturing a trench-type insulated gate bipolar transistor package structure according to claim 8, wherein: The preset time is 1 millisecond to 10 milliseconds.

10. The method for manufacturing a trench-type insulated gate bipolar transistor package structure according to claim 8, wherein: After completing the electrical connection between the trench-type insulated gate bipolar transistor chip and the corresponding pins on the lead frame, the combined device of the trench-type insulated gate bipolar transistor chip and the lead frame is filled with plastic packaging material to form a fully filled plastic package shell.

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