JPH10284522A - Flat type semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make offset of a spring hard to occur during transportation of an element by constituting an integral spring by mutually connecting unit springs which press each contact terminal to each semiconductor chip without pressurizing an upper board and a lower board which hold a semiconductor chip and a contact terminal body from top and bottom. SOLUTION: A unit spring 31 is formed by bending an annular spring material whose outer shape is almost square, and an integral spring 30 is constituted by connecting the unit springs 31 mutually by an outer frame 32. The integral spring 30 is used so that the outer frame 32 and a leg part 35 of the unit spring 31 come into contact with an upper board and a top 33 of the unit spring 31 comes into contact with a contact terminal. The unit spring 31 is a plate spring. According to this constitution, it is possible to reduce the number of parts when compared to a flat type semiconductor device wherein a separate spring is used for each semiconductor chip, thus greatly reducing the number of processes during assembly. Furthermore, offset of spring caused by transportation, etc., can be prevented since the spring is formed to an integral spring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a semiconductor chip having first and second main electrodes on two opposing main surfaces, such as an insulated gate bipolar transistor and a freewheel diode, and upper and lower main electrodes. The present invention relates to a flat type semiconductor device.

[0002]

2. Description of the Related Art An insulated gate bipolar transistor (hereinafter abbreviated as IGBT) is a voltage-driven type which is easy to handle, and has a feature that the ON voltage is small due to conductivity modulation by minority carrier injection. It is widely used in PWM control inverters for motors and the like. And recent market demands are toward higher capacity. Under such circumstances, in order to increase the capacity of the IGBT, in addition to increasing the capacity of one chip, a module structure in which a plurality of chips are integrated in the same package has been adopted.

In a power device having a control electrode of a MOS (metal-oxide-semiconductor) structure such as an IGBT, an emitter electrode and a gate electrode are formed side by side on one main surface of a semiconductor chip. For this, IGBT
When the chip is incorporated in a package container, the collector electrode formed on the lower surface side can be pulled out by mounting the IGBT chip on a metal base that also functions as a radiator, but the emitter electrode and the gate electrode are separated. Must be pulled out via an external lead terminal. Therefore, in the conventional package assembly structure, an emitter and an external lead terminal for a gate are provided on the upper surface side of the package container together with the metal base, and a wire is provided between the emitter electrode and the external lead terminal, and between the gate electrode and the external lead terminal. An aluminum conducting wire having a diameter of about 300 μm was drawn out by wire bonding. By the way, in the above-mentioned conventional assembly structure, heat can be radiated from the collector side, but heat radiation from the emitter side is hardly performed, so that the current capacity is greatly limited. Also, in the case of a large current capacity, the number of bonding wires connected to the emitter electrode also increases. Particularly, in a module configuration in which a plurality of IGBT chips are incorporated in the same package, the number of wires is several hundreds. However, there is a problem that the internal wiring inductance increases and a large surge occurs during the switching operation,
There are also reliability issues.

In order to solve the problems of heat dissipation and wiring inductance by the wire bonding structure,
It is considered that the IGBT chip is incorporated in a flat package like a flat semiconductor, and the emitter electrode and the collector electrode formed on the main surface are brought into surface contact with the electrode plates exposed on the upper and lower surfaces of the package, respectively, and are drawn out. Can be
However, when an IGBT is brought into contact with a gate electrode by pressing a package-side electrode plate under pressure, a pressing force is applied to the gate structure, which may cause stress, and cannot be put to practical use with a conventional flat semiconductor device.

For this reason, a portion called a collector is provided on the emitter side of a device having a MOS structure for the purpose of providing a current path and heat dissipation without forming a MOS structure.
A method of accurately arranging the contact terminal body by a positioning guide has been adopted. FIGS. 4A and 4B are main part configuration diagrams of a conventional flat semiconductor device. FIG. 4A is a sectional view, and FIG. 4B is a plan view excluding an upper plate. In FIG. 4, the upper plate 7
Between the lower plate 8 and the substrate 9 from below,
Each of the chip 1 and the contact terminal body 4 which are soldered by the reference numeral 0 is positioned by the positioning guide 11. Reference numeral 12 denotes an insulating ring fixed to the upper plate 7 and the lower plate 8 and including the IGBT chip 1. Spring 1
5 is positioned by the upper convex portion 14 of the contact terminal body 4, and the spring 15 presses the upper plate 7 and the contact terminal body 4. During use, good surface contact between the chip 1 and the contact terminal body 4 is obtained by applying pressure to the upper plate 7 and the lower plate 8. The springs 15 are independently inserted into the contact terminal bodies 4 one by one.

FIG. 5 is a plan view of the IGBT chip on the emitter side. A collector electrode 2 having no MOS structure connected to the emitter electrode is arranged, and a contact terminal body is brought into pressure contact with the collector electrode 2. In addition, a gate pad 3 connected to the gate electrode for taking out a gate lead is provided. 6A and 6B are main part structural diagrams of the contact terminal body, wherein FIG. 6A is a plan view and FIG. 6B is a cross-sectional view. In FIG. 6, the contact terminal 4 is an IG
A convex chip pressing portion 5 provided to press the emitter side of the BT chip is provided, and an upper convex portion 14 is provided on a surface facing the chip pressing portion 5. As the structure of the present contact terminal, the upper convex portion 14 is provided within a range of a line obtained by projecting a line connecting the outside of the chip pressing portion 5 to the facing surface. The contact terminal body 4 also serves as a current path and a cooling body.

FIG. 7 is a perspective view of a conventional spring 15. An annular spring material having a substantially square outer shape was bent to form a spring. This spring 15 is connected to the upper convex portion 14 of the contact terminal body 4.
Assembled according to. In this case, the apex 33 contacts the upper plate 7 and the foot 35 contacts the contact terminal body 4. Further, the arm portion 34 acts as a spring.

[0008]

As described above, when one independent spring is mounted on each semiconductor chip, the number of assembly steps increases. In addition, during element transport, the spring is displaced due to vibration, impact, or the like, causing a problem that the semiconductor chip is damaged. SUMMARY OF THE INVENTION An object of the present invention is to provide a flat semiconductor device having a spring which solves the above-mentioned problems and has a small number of assembling steps and is unlikely to be displaced by vibration, impact, or the like during element transportation. .

[0009]

In order to achieve the above object, a semiconductor device of the present invention comprises a plurality of semiconductor chips having first and second main electrodes on two main surfaces, respectively, A line connecting the outer periphery of the chip pressing portion to a surface of the contact terminal body having a convex chip pressing portion that is in contact with the first main electrode of the chip and facing the surface where the chip pressing portion is located. Having a convex portion on the inner side of the line projected to each of the contact terminals, arranged around the respective contact terminals, and individually sandwiches the individual contact terminals corresponding to the respective semiconductor chips and the semiconductor chips and the contact terminals from above and below. An upper plate, a lower plate, and an insulating ring fixed to the upper plate and the lower plate and including the semiconductor chip. Each contact terminal body is attached to each semiconductor chip in a state where the upper plate and the lower plate are not pressed. With the unit spring to press In those comprising, a configuration is integral spring each unit springs are connected to each other.

[0010] By forming the unit springs as integral springs connected to each other, the number of assembling steps can be reduced and the manufacturing cost can be reduced. Further, the probability that the unit springs are displaced due to vibration during transportation or the like can be greatly reduced as compared with the case where the unit springs are not connected to each other and are independent. Further, the unit spring may be formed of a ring-shaped and bent leaf spring.

As described above, by using a leaf spring, a predetermined pressing force can be obtained with a small spring thickness. Further, it is effective if the apex of the bent leaf spring is separated at a predetermined width. With this configuration, the leaf spring is smoothly deformed by the pressing force.

[0012]

FIG. 1 is a structural view of a flat type semiconductor device according to an embodiment of the present invention. FIG. 1 (a) is a sectional view of a main part of a flat type semiconductor device on which an IGBT chip is mounted, and FIG. 2B is a plan view of a main part of the flat type semiconductor device of FIG. In FIG. 1A, a lower plate 8 is placed from below in a package including a ceramic insulating ring 12 and an upper plate 7 and a lower plate 8 having bellows fixed thereto.
A substrate 9, a chip 1 soldered to the substrate 9 with solder 10, and a contact terminal 4 between
Are accurately positioned by the positioning guides 11, and the integrated spring 30 having the unit spring 31 is inserted around the upper convex portion 14 of the contact terminal body 4 and positioned. The substrate 9 is positioned on the lower plate 7 of the package by means not shown. Reference numeral 16 denotes a solder escape portion. The positioning guide 11 is positioned by a groove 13 provided in the substrate 9. Even when each of the contact terminals 4 is not at the time of element pressurization, the integrated spring 30
Pre-pressurized in the package. At the time of use, a good surface contact between the chip 1 and the contact terminal body 4 is obtained by applying a pressure equal to or higher than the preliminary pressurization to the upper plate 7 and the lower plate 8. The gate electrode of the IGBT chip 1 is composed of the contact terminal 4 and the positioning guide 1.
It is wire-bonded to the gate terminal 17 of the insulating ring 12 through one hole through an insulating terminal (not shown) provided on the substrate 9. As described above, the IGBT is of the voltage drive type, and the gate signal requires only a small current.
The gate lead may be of a wire bonding type.

In FIG. 1B, a positioning guide 11 placed in a groove 13 of a substrate 9 and a contact terminal 4 are mounted in an insulating ring 12, and an upper protrusion 14 of the contact terminal is formed. The unit springs 31 are mounted so as to surround the periphery, and each unit spring 31 is partially connected to the outer frame 32. The unitary spring 31 connected by the outer frame 32 forms the integral spring 30. Although the insulating ring 12 made of ceramic is modeled in the drawing and the corner portion is drawn at a right angle, it is actually in the shape of an arc.

FIG. 2 is a perspective view showing an example of the integral spring applied to FIG. An annular spring material having a substantially square outer shape is bent to form a unit spring 31, and the unit springs 31 are connected to each other by an outer frame 32 to form an integrated spring 30. As shown in FIG. 1, the integral spring 30 has the outer frame 32 and the foot 35 of the unit spring 31 in contact with the upper plate 7 and the unit spring 3
The vertex 33 of 1 is used in contact with the contact terminal body 4. Just use it upside down from FIG.
The unit spring 31 is a leaf spring as shown in the figure.

In this case, the number of parts can be reduced and the number of steps in assembling can be greatly reduced as compared with a conventional flat type semiconductor device using an independent spring for each semiconductor chip. In addition, the use of the integral spring can prevent the displacement of the spring due to transportation or the like. FIG. 3 is a modified example of FIG. 2 and is a perspective view of another integrated spring. Unit spring 31
Are separated by a predetermined width W.

By cutting off by a predetermined width W in this manner, it is possible to prevent the deformation of the arm portion 34 from extending to the foot portion 35 when the leaf spring sinks due to pressure, and to prevent the foot portion 34 from being abnormally deformed. Therefore, the pressure of the leaf spring is smoothly transmitted to the semiconductor chip, and the spring function is improved as compared with FIG.
The predetermined width W is a width in which the vertices 33a separated when the leaf spring sinks are not in contact with each other, and 1 mm to several mm.
Good degree.

The internal dimensions of the unit springs 31 are adapted to the shape of the upper projections 14 of the contact terminal body 4. Each unit spring 31 is inserted into the upper projections 14, and the integrated spring 30 is positioned.

[0018]

As described above, according to the present invention, the unit springs are partially connected to form an integrated spring, thereby simplifying the work in the assembling process and improving the assembling efficiency. Man-hours can be reduced. In addition, by integrating the spring, even when the element is not pressurized during transportation,
The semiconductor chip and the contact terminal body do not become free, and the displacement of the spring due to vibration or the like is prevented from occurring, the semiconductor chip is prevented from being damaged, and the reliability of the semiconductor device is improved. it can.

[Brief description of the drawings]

1A and 1B are configuration diagrams of a flat semiconductor device according to an embodiment of the present invention, in which FIG. 1A is a cross-sectional view of a main part of a flat semiconductor device on which an IGBT chip is mounted, and FIG. Main part plan view of the device without the upper plate

FIG. 2 is a perspective view of an integrated spring applied in FIG. 1;

FIG. 3 is a perspective view of a modified example of FIG. 2, showing an integrated spring;

FIGS. 4A and 4B are main part configuration diagrams of a conventional flat semiconductor device, and FIG.
Is a cross-sectional view, and (b) is a plan view without the upper plate.

FIG. 5 is a plan view of the IGBT chip on the emitter side.

6 (a) is a plan view, and FIG. 6 (b) is a cross-sectional view.

FIG. 7 is a perspective view of a conventional spring 15;

[Explanation of symbols]

 Reference Signs List 1 IGBT chip 2 Emitter collecting electrode 3 Gate pad 4 Contact terminal body 5 Chip pressing part 6 Upper pressing surface 7 Upper plate 8 Lower plate 9 Metal substrate 10 Solder 11 Positioning guide 12 Insulating ring 13 Groove 14 Upper convex part 15 Spring 16 Solder Relief portion 17 Gate terminal 30 Integrated spring 31 Unit spring 32 Outer frame 33 Apex 33a Apex 34 Arm 35 Foot W Predetermined width

Claims (3)

[Claims] 1. A semiconductor device comprising: a plurality of semiconductor chips having first and second main electrodes on two main surfaces thereof; and a convex chip pressing portion in contact with the first main electrode of the semiconductor chip. On the surface of the contact terminal body opposite to the surface where the chip pressing portion is located, a projection connecting the line connecting the outer periphery of the chip pressing portion to the surface is provided on the inner side, and the periphery of each contact terminal body is provided. Arranged and individually contact terminal bodies corresponding to each semiconductor chip, an upper plate and a lower plate sandwiching the semiconductor chip and the contact terminal body from above and below, and a semiconductor chip fixed to the upper plate and the lower plate. A unit spring that presses each contact terminal body against each semiconductor chip without applying pressure to the upper plate and the lower plate, wherein the unit springs are connected to each other. Is Flat and wherein a and. 2. The flat semiconductor device according to claim 1, wherein the unit spring is formed of a ring-shaped and bent leaf spring. 3. The flat semiconductor device according to claim 2, wherein the apex of the bent leaf spring is cut off at a predetermined width.