Groove-type insulated gate bipolar transistor packaging structure and manufacturing method thereof
阅读说明：本技术 一种沟槽型绝缘栅双极型晶体管封装结构及其制作方法 (Groove-type insulated gate bipolar transistor packaging structure and manufacturing method thereof ) 是由 梁赛嫦 马颖江 史波 江伟 于 2018-08-06 设计创作，主要内容包括：本发明涉及晶体管封装技术领域,公开了一种沟槽型绝缘栅双极型晶体管封装结构及其制作方法,该沟槽型绝缘栅双极型晶体管封装结构包括：沟槽型绝缘栅双极型晶体管,沟槽型绝缘栅双极型晶体管包括与发射极电连接的发射极金属层以及位于发射极金属层一侧的沟槽型栅极；引线框架,引线框架包括用于固定沟槽型绝缘栅双极型晶体管的芯片放置区以及发射极引出端；连接发射极金属层与发射极引脚的第一焊线,第一焊线一端与发射极金属层背离沟槽型栅极的表面连接形成条形的第一焊点,另一端与发射极引出端连接形成第二焊点,且第一焊点的延伸方向垂直于沟槽型栅极沟槽的延伸方向。该封装结构减小了单个沟槽的应力,提高了焊线良率,提高了芯片的可靠性。(The invention relates to the technical field of transistor packaging, and discloses a trench type insulated gate bipolar transistor packaging structure and a manufacturing method thereof, wherein the trench type insulated gate bipolar transistor packaging structure comprises the following components: the groove type insulated gate bipolar transistor comprises an emitting electrode metal layer electrically connected with an emitting electrode and a groove type grid electrode positioned on one side of the emitting electrode metal layer; the lead frame comprises a chip placing area for fixing the groove type insulated gate bipolar transistor and an emitting electrode leading-out end; and one end of the first welding wire is connected with the surface of the emitter metal layer, which deviates from the groove-shaped grid electrode, to form a strip-shaped first welding point, the other end of the first welding wire is connected with the leading-out end of the emitter to form a second welding point, and the extending direction of the first welding point is vertical to the extending direction of the groove-shaped grid electrode groove. The packaging structure reduces the stress of a single groove, improves the yield of bonding wires and improves the reliability of a chip.)
1. A trench-type IGBT packaging structure is characterized by comprising:
the trench-type insulated gate bipolar transistor comprises an emitting electrode metal layer electrically connected with an emitting electrode and a trench-type grid electrode positioned on one side of the emitting electrode metal layer;
the lead frame comprises a chip placing area for fixing the groove type insulated gate bipolar transistor and an emitting electrode leading-out end;
and one end of the first welding wire is connected with the surface of the emitter metal layer, which deviates from the groove-shaped grid electrode, to form a strip-shaped first welding point, the other end of the first welding wire is connected with the leading-out end of the emitter to form a second welding point, and the extending direction of the first welding point is perpendicular to the extending direction of the groove-shaped grid electrode groove.
2. The trench-type igbt package structure of claim 1, wherein a portion of the first bonding wire between the first pad and the second pad forms an arc, and a highest point of the arc is 750 to 1000 μm higher than an arc of the emitter metal layer.
3. The trench igbt package structure of claim 1, wherein the emitter terminal has a first bonding pad for connection to the first bonding wire, and the second bonding pad is formed on the first bonding pad.
4. The trench igbt package structure of claim 3, wherein at least one first bonding wire is connected between the emitter metal layer and the first bonding pad.
5. The trench-type igbt package structure of claim 1, wherein the lead frame further comprises a gate terminal, and the trench-type gate is electrically connected to the gate terminal by a second bonding wire.
6. The trench-type igbt package structure of claim 1, wherein the trench-type igbt comprises a silicon substrate, the trench-type gate formed on the silicon substrate, a silicon oxide insulating layer formed on a surface of the trench-type gate, and the emitter metal layer formed on a side of the silicon oxide insulating layer facing away from the silicon substrate.
7. The trench-type igbt package structure of claim 6, wherein the trench-type igbt further comprises a collector electrode on a side of the silicon substrate facing away from the trench-type gate electrode, the lead frame further comprises a collector electrode terminal, and the collector electrode is electrically and physically connected to the chip-placement region of the lead frame by a bonding material.
8. The trench-type igbt package structure of claim 1, further comprising a plastic package casing formed by a plastic packaging process with a complete interior fill.
9. A method of fabricating the trench-type igbt package structure according to any one of claims 1 to 8, comprising:
fixing the groove type insulated gate bipolar transistor in a chip placing area of the lead frame;
adopting ultrasonic welding cleaver to weld by pressure to ensure that one end of a first welding wire is connected with an emitter metal layer of the groove type insulated gate bipolar transistor and form a strip-shaped first welding point with the extending direction vertical to the extending direction of the groove type grid electrode;
vertically lifting the ultrasonic welding chopper and staying for a certain preset time to enable the first welding line to generate an arc height with a set height;
and jumping the ultrasonic welding cleaver to the leading-out end of the emitting electrode of the lead frame for pressure welding, so that the first welding wire is connected with the leading-out end of the emitting electrode and forms a second welding point.
10. The method of claim 9, wherein the predetermined time is 1 ms to 10 ms.
11. The method of claim 9, wherein the first wire has an arc height of 750 μm to 1000 μm.
12. The method of claim 9, wherein after the trench igbt chip is electrically connected to the corresponding lead on the lead frame, the combined device of the trench igbt chip and the lead frame is filled with a molding compound to form a plastic package with a completely filled interior.
Technical Field
The invention relates to the technical field of transistor packaging, in particular to a groove type insulated gate bipolar transistor packaging structure and a manufacturing method thereof.
Background
An Insulated Gate Bipolar Transistor (IGBT for short) is mainly applied to the fields of alternating current motors, frequency converters, switching power supplies, lighting circuits, traction transmission and the like of variable frequency air conditioners. Because the IGBT is actually a circuit switch, and is used for strong currents of several hundred to several thousand volts and several tens to several hundreds amperes, its reliability level is much higher than that of ordinary consumer electronics.
The IGBT process technology comprises two types: planar (planar) and trench (trench) structures. The groove type structure is a novel technology, and on the basis of not influencing any other electrical characteristics, the unit density of the unit is improved, and further the conduction loss is greatly improved. Therefore, the trench type IGBT is thinner, higher in current density, and lower in cost than the planar type IGBT.
The groove type IGBT is easy to burn out due to rapid increase of leakage current during verification of the reliability performance, and the main reason is that weak links exist on the surface of the chip or in a certain area of the chip. The method for optimizing the reliability of the trench type IGBT comprises the following steps: firstly, improving a chip structure; and secondly, improving through a packaging stage. On the whole design of the IGBT device, if the chip specific parameters of the device are confirmed, the improvement of the chip reliability by reflow is basically impossible (due to long reflow period and high cost). In view of this, the most rapid, cost-effective and efficient way is to improve the reliability of the whole device by packaging the chip.
At present, no mature packaging technology aiming at the thin trench type IGBT exists in China. For the bonding process of the bonding wire, the reliability of the bonding wire is improved only by coordinating three parameters of power, force and time in the bonding wire process, the first bonding point of the bonding wire connected with the chip is not controlled, the number of grooves below the first bonding point is small, and a small number of grooves bear large compressive stress during welding to cause damage.
Disclosure of Invention
The invention provides a groove-type insulated gate bipolar transistor packaging structure and a manufacturing method thereof.
In order to achieve the purpose, the invention provides the following technical scheme:
a trench-type IGBT package structure, comprising:
the trench-type insulated gate bipolar transistor comprises an emitting electrode metal layer electrically connected with an emitting electrode and a trench-type grid electrode positioned on one side of the emitting electrode metal layer;
the lead frame comprises a chip placing area for fixing the groove type insulated gate bipolar transistor and an emitting electrode leading-out end;
and one end of the first welding wire is connected with the surface of the emitter metal layer, which deviates from the groove-shaped grid electrode, to form a strip-shaped first welding point, the other end of the first welding wire is connected with the leading-out end of the emitter to form a second welding point, and the extending direction of the first welding point is perpendicular to the extending direction of the groove-shaped grid electrode groove.
The packaging structure of the groove type insulated gate bipolar transistor comprises a groove type insulated gate bipolar transistor, a lead frame and a first welding wire electrically connected with the groove type insulated gate bipolar transistor and the lead frame, wherein the groove type insulated gate bipolar transistor is provided with an emitting electrode metal layer electrically connected with an emitting electrode and a groove type grid electrode positioned on one side of the emitting electrode metal layer, the lead frame is provided with a chip placing area for fixing the groove type insulated gate bipolar transistor and an emitting electrode leading-out end, the groove type insulated gate bipolar transistor is fixed in the chip placing area, the emitting electrode metal layer is electrically connected with the emitting electrode leading-out end through the first welding wire, the extending direction of a strip-shaped first welding point connected with the emitting electrode metal layer is vertical to the extending direction of a groove of the groove type grid electrode, and the extending direction of the strip-shaped first welding point is vertical to the extending, the first welding point can press more grid grooves, so that more grid grooves share the pressure of the first welding point, the stress of a single groove is reduced, chip damage during welding is avoided, the yield of welding wires is improved, and the reliability of the whole chip is improved.
Preferably, the part of the first bonding wire between the first bonding point and the second bonding point forms an arc-shaped part, and the highest point of the arc-shaped part is 750 micrometers to 1000 micrometers away from the arc height of the emitter metal layer.
Preferably, the emitter terminal has a first bonding pad for connection with the first bonding wire, and the second bonding pad is formed on the first bonding pad.
Preferably, at least one first bonding wire is connected between the emitter metal layer and the first bonding pad.
Preferably, the lead frame further comprises a gate terminal, and the trench gate is electrically connected with the gate terminal through a second bonding wire.
Preferably, the trench-type insulated gate bipolar transistor includes a silicon substrate, the trench-type gate formed on the silicon substrate, a silicon oxide insulating layer formed on the surface of the trench-type gate, and the emitter metal layer formed on the side of the silicon oxide insulating layer away from the silicon substrate.
Preferably, the trench-type igbt further includes a collector located on a side of the silicon substrate facing away from the trench-type gate, and the lead frame further includes a collector terminal, and the collector is electrically and physically connected to the chip placement region of the lead frame through a bonding material.
Preferably, the plastic package shell is formed by a plastic package process and is completely filled inside.
The invention also provides a method for manufacturing the trench-type insulated gate bipolar transistor packaging structure provided by any technical scheme, which comprises the following steps:
fixing the groove type insulated gate bipolar transistor in a chip placing area of the lead frame;
adopting ultrasonic welding cleaver to weld by pressure to ensure that one end of a first welding wire is connected with an emitter metal layer of the groove type insulated gate bipolar transistor and form a strip-shaped first welding point with the extending direction vertical to the extending direction of the groove type grid electrode;
vertically lifting the ultrasonic welding chopper and staying for a certain preset time to enable the first welding line to generate an arc height with a set height;
and jumping the ultrasonic welding cleaver to the leading-out end of the emitting electrode of the lead frame for pressure welding, so that the first welding wire is connected with the leading-out end of the emitting electrode and forms a second welding point.
According to the manufacturing method of the groove type insulated gate bipolar transistor packaging structure, the ultrasonic welding chopper is adopted for pressure welding to form a strip-shaped first welding point perpendicular to the extending direction of the groove type grid groove, after the first welding point is finished, the ultrasonic welding chopper is vertically lifted to form an arc height with a set height, the ultrasonic welding chopper is adjusted to the leading-out end of the emitting electrode of the lead frame to be pressure welded to form a second welding point, and the welding pressure on the first welding line is finished.
Preferably, the preset time is 1 to 10 milliseconds.
Preferably, the first bonding wire has an arc height of 750 to 1000 microns.
Preferably, after the electrical connection between the trench-type igbt chip and the corresponding pin on the lead frame is completed, the bonding device between the trench-type igbt chip and the lead frame is filled with a molding compound to form a plastic package casing with a completely filled interior.
Drawings
Fig. 1 is a schematic structural diagram of a trench-type igbt according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a trench gate according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a trench-type igbt package structure according to an embodiment of the present invention;
FIG. 4 is a top view of the schematic structure of FIG. 3;
fig. 5 is a flowchart of a method for manufacturing a trench-type igbt package structure according to an embodiment of the present invention.
Icon:
1-trench type insulated gate bipolar transistor; 11-a silicon substrate; 12-trench gate; 13-a silicon oxide insulating layer; 14-an emitter metal layer; 2-a lead frame; 21-chip placement area; 22-first writing pad; 23-second pad; 24-a collector terminal; 3-a first bonding wire; 31-a first solder joint; 32-second solder joint; 33-an arc-shaped portion; 4-binding material.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1 to fig. 3, the present invention provides a trench type igbt package structure, including:
the trench-type insulated gate bipolar transistor 1 comprises an
the lead frame 2 comprises a chip placing area 21 for fixing the groove type insulated gate bipolar transistor 1 and an emitting electrode leading-out end;
and the first welding wire 3 is used for connecting the
The trench-type igbt package structure according to the above embodiment of the invention includes a trench-type igbt 1, a lead frame 2, and a first bonding wire 3 electrically connecting the trench-type igbt 1 and the lead frame 2, where the trench-type igbt 1 has an
In the embodiment of the present invention, specifically, as shown in fig. 3, the portion of the first bonding wire 3 between the first bonding pad 31 and the second bonding pad 32 forms the arc portion 33, and the highest point of the arc portion 33 is 750 micrometers to 1000 micrometers higher than the arc height of the
In the above embodiment of the invention, as shown in fig. 4, the emitter terminal has the first bonding pad 22 for connecting with the first bonding wire 3, and the second bonding pad 32 is formed on the first bonding pad 22, so as to electrically connect the
In the above embodiment of the invention, at least one first bonding wire 3 is connected between the
In the embodiment of the invention, as shown in fig. 4, the lead frame 2 further includes a gate terminal, and the
In the embodiment of the invention, specifically, as shown in fig. 1, the trench-type insulated gate bipolar transistor 1 includes a
In the embodiment of the invention, the trench-type igbt 1 further includes a collector located on a side of the
It should be noted that the position arrangement of the wiring pads on the lead frame 2 may be designed differently according to actual production, and is not limited to the structure shown in fig. 4.
In the embodiment of the invention, the plastic package shell which is formed by the plastic package process and is completely filled inside is further included, so that no cavity is left inside the plastic package device, the welding yield of welding wires is improved, and the overall reliability of the device is improved.
In the embodiment of the present invention, the first bonding wire 3 is a metal conductor, such as an aluminum wire or a copper wire, which can save the manufacturing cost.
The invention further provides a method for manufacturing the trench-type insulated gate bipolar transistor packaging structure provided in any of the above embodiments, as shown in fig. 5, the method includes the following steps:
s501: fixing the groove type insulated gate bipolar transistor in a chip placing area of the lead frame;
s502: adopting ultrasonic welding cleaver to weld by pressure to ensure that one end of a first welding wire is connected with an emitter metal layer of the groove type insulated gate bipolar transistor and form a strip-shaped first welding point with the extending direction vertical to the extending direction of the groove type grid electrode;
s503: vertically lifting the ultrasonic welding chopper and staying for a certain preset time to enable the first welding line to generate an arc height with a set height;
s504: and jumping the ultrasonic welding cleaver to the leading-out end of the emitting electrode of the lead frame for pressure welding, so that the first welding wire is connected with the leading-out end of the emitting electrode and forms a second welding point.
In the manufacturing method of the trench-type insulated gate bipolar transistor packaging structure provided by the embodiment of the invention, the ultrasonic welding chopper is adopted to perform pressure welding to form the strip-shaped first welding point which is vertical to the extending direction of the trench-type gate groove, after the first welding point is finished, the ultrasonic welding chopper is vertically lifted to form the arc height with the set height, the ultrasonic welding chopper is adjusted to the leading-out end of the emitter of the lead frame to perform pressure welding to form the second welding point, and the welding to the first welding line is finished.
The principle of the ultrasonic welding is as follows: and applying certain pressure in the vertical direction and certain vibration frequency in the plane direction of the chip to combine the metal layer above the chip with the bonding wire to form a first welding point.
In the embodiment of the invention, the preset time may be set to 1 ms to 10 ms in order to improve the utilization rate of time according to the specific situation of industrial production.
In the above embodiment of the invention, the arc height of the first bonding wire with the set height may be 750 to 1000 microns. The arc height in the range is higher than that of the conventional welding wire, so that the pressure of the welding wire is uniformly distributed on more grooves, the stress of each groove is further balanced, the chip damage during welding is avoided, and the yield of the welding wire is improved; and because the arc part 33 of the first bonding wire 3 is pulled up, the distance between the first bonding wire 3 and the chip is increased, which is beneficial to completely filling the plastic package material when the chip is plastically packaged, improves the bonding wire welding yield and improves the overall reliability of the device.
In the embodiment of the invention, after the electric connection between the groove type insulated gate bipolar transistor chip and the corresponding pin on the lead frame is completed, the plastic package material is adopted to fill the combined device of the groove type insulated gate bipolar transistor chip and the lead frame to form the plastic package shell with the fully filled interior, so that the plastic package device is ensured to be fully filled with the interior without leaving a cavity, the welding yield of the welding wire is improved, and the overall reliability of the device is improved. Preferably, the plastic package material is filled along the mold flow direction during filling, that is, during the plastic package process of the product, the molten plastic package material is filled into the product through the glue injection port of the plastic package mold.
It will be apparent to those skilled in the art that various changes and modifications may be made in the embodiments of the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
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