JP2000183281A - Semiconductor device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reliability of a semiconductor device that is sealed with resin. SOLUTION: A semiconductor device is provided with a structure body, that has a semiconductor element 11, a first resin layer 1 for covering an electrode plate 13 where a semiconductor element is mounted and lead electrodes 4 and 5, and a second resin layer 2 adhering to the electrode plate, the lead electrodes, and a base substrate 6 among the electrode plate, the lead electrodes, and the base substrate 6, and a third resin layer 3 for covering the structure body, so that one portion of the lead electrode and the surface of the base substrate are exposed. Protection by the first resin layer 1 prevents failures from occurring, when cutting a lead to evaluate electrical characteristics in a manufacturing process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device in which a semiconductor element is sealed with a resin.

[0002]

2. Description of the Related Art As a conventional power semiconductor device of this type, there is a structure disclosed in Japanese Patent Application Laid-Open No. 9-102580. That is, a semiconductor element is mounted on a lead frame to form a main circuit portion. Next, the lead frame is fixed with the first resin and integrally sealed with the second resin to form a semiconductor device. This structure has the following problems.

In order to evaluate the electrical characteristics during the manufacturing process, it is necessary to cut and separate a part of the lead frame.
However, in the semiconductor device having this structure, the lead frame is cut while the power semiconductor element is mounted, and a failure of the semiconductor element occurs due to mechanical stress, heat or dust generated at the time of cutting. However, there is a problem in that the adhesion portion between the lead frame and the first resin is easily separated.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the problems of the above-mentioned conventional method, and facilitates partial cutting or molding of a lead frame during a manufacturing process and evaluation of characteristics to improve reliability. A power semiconductor device having a low thermal resistance is provided.

[0005]

A semiconductor device according to the present invention comprises: a semiconductor element; an electrode plate on which the semiconductor element is mounted;
The semiconductor device includes a lead electrode electrically connected to the semiconductor element, and a substrate on which the semiconductor element, the electrode plate, and the lead electrode are mounted. The semiconductor element, the electrode plate and the lead electrode are covered with a first resin layer, and the electrode plate, the lead electrode and the substrate are bonded to each other between the electrode plate and the lead electrode by the second resin layer. . The above-described structure is covered with the third resin layer so that a part of the lead electrode and the surface of the substrate are exposed.

In the above-described semiconductor device, it is possible to cut the lead and evaluate the electrical characteristics while the semiconductor element, the electrode plate and the lead electrode are protected by the first resin layer. Therefore, it is possible to prevent a failure that may occur at the time of cutting the lead or evaluating the electrical characteristics.

[0007] The semiconductor device having the above structure preferably further includes a spacer means located in the resin layer. Since the second resin layer can be uniformly set to a desired thickness by the spacer means, insulation can be ensured, and thermal conductivity can be improved and thermal resistance can be reduced. As the spacer means, the protrusion of the first resin layer or any one of the insulating materials of alumina, magnesia, silica, beryllia, zirconia, silicon nitride, aluminum nitride, and silicon carbide is used. There is a member to do. The spacer means is preferably spherical in shape, and the diameter of the spherical shape is preferably substantially equal to the thickness of the second resin layer. In order to reduce the thermal resistance, it is also effective that the second resin layer contains 50% by volume or more and 95% by volume or less of an inorganic material-based filler.

The semiconductor device according to the present invention can be manufactured by the following method for manufacturing a semiconductor device according to the present invention. That is, the manufacturing method according to the present invention includes a first step of mounting a semiconductor element on an electrode plate of a lead frame having an electrode plate and a lead electrode, and covering the semiconductor element and the lead frame with a first resin layer. A second step of cutting the lead frame, a fourth step of crimping the substrate and the lead frame via the second resin layer, a step of cutting the lead frame, the semiconductor element, the first and the second steps. A fifth resin layer covering the structure including the second resin layer and the substrate with the third resin layer;
And a step of

According to the above manufacturing method, the lead is cut while the semiconductor element and the lead frame are protected by the first resin layer. Therefore, it is possible to prevent a failure that may occur when the lead is cut.

In the above-described manufacturing method, it is preferable that a step of evaluating an electric characteristic of a circuit including a semiconductor element is included between the third step and the fourth step. This allows
It is possible to prevent a failure that occurs at the time of evaluating the electrical characteristics.

In the above-mentioned manufacturing method, it is preferable that a projection is formed on the first resin layer in the second step, and that the projection is pressure-bonded to the substrate in the fourth step. This projection serves as the spacer means described above. Further, in the fourth step, a spacer may be included in the second resin layer. It is preferable that the spacer is a member or a shape of the insulating material as described above.

As the semiconductor element, various switching elements such as bipolar transistors and MOSFETs, diodes and the like can be applied. Further, the circuit including the semiconductor element may further include a passive element such as a resistor, a capacitor, and an inductor. These electric or electronic elements may be mounted on a circuit board such as a printed board. Further, the semiconductor device according to the present invention is suitable for a semiconductor device in which a power semiconductor element such as a power transistor, a power MOSFET, and an insulated gate bipolar transistor (hereinafter, referred to as IGBT) is resin-sealed, because the thermal resistance can be reduced. .

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

(Embodiment 1) FIG. 1 is a sectional view of a semiconductor device according to Embodiment 1 of the present invention. For example, IGBT (Insu
Power semiconductor elements 11 and 12 such as a related gate bipolar transistor are fixed and mounted on the main surface of the electrode plate portion 13 of the lead frame via the solder adhesive layer 14. The other main surface of the electrode plate portion 13, that is, the back surface of the main surface on which the above components are mounted, is bonded to the metal base substrate 6 via the resin layer 2. Power semiconductor elements 11 and 12 are connected to lead electrode sections 4 and 5 by aluminum wire bonding section 15.
Are electrically connected to each other, and a part of the lead electrode portions 4 and 5 is led out as terminals to form a main circuit. Further, the main circuit portion is covered with the resin layer 1 to form a structure, and the entire structure is integrally molded with the resin layer 3 so that the terminal portions of the lead electrode portions 4 and 5 and the back surface of the metal base substrate 6 are exposed. Is done. The resin layer 1 has a projection 8 between the electrode plate 13 or the lead electrodes 4 and 5 and the metal base substrate 6. The protrusion 8 substantially penetrates the resin 2 in its thickness direction. For this reason, the projection 8 serves as a spacer, and secures the thickness of the resin 2.

The power semiconductor device of this embodiment is manufactured by the following manufacturing method. FIG. 2 shows a series of steps collectively. For example, a Cu lead frame having a predetermined pattern shape and a thickness of 0.7 mm is formed by press working (step 1). An IGBT chip as a power semiconductor element is mounted on one main surface of the electrode plate portion of the lead frame and soldered (step 2). Next, a main circuit is formed by electrically connecting the power semiconductor element and the lead electrode portion of the lead frame with an Al wire having a diameter of 0.3 mm (step 3). The resin layer 1 is formed by primary molding with an epoxy resin so as to protect the main circuit portion (step 4). At this time, the protrusion 8 protruding toward the other main surface side is formed simultaneously with the resin layer 1. In this state, a part of the lead frame is cut so that characteristics can be measured (Step 5), and electrical characteristics are evaluated (Step 6). Further, the other main surface side of the primary molded circuit portion whose characteristics have been confirmed is integrated by heating and pressing on a base substrate to which an uncured epoxy resin green sheet is adhered. (Step 7). In this step, the resin layer 2 having a uniform and stable layer thickness and excellent heat conduction properties and insulation properties is obtained by the projections 8.

The structure prepared in the above steps is set in a mold, and the mold is filled with an epoxy resin under predetermined conditions to form a resin layer 3 and integrally resin-sealed (step 8). After the molding, a sufficient curing treatment is performed (Step 9), and finally, unnecessary portions of the lead frame are cut and lead-molded to obtain a semiconductor device having a predetermined shape (Step 10). In the above-mentioned step 7, in step 8, the two pieces to be bonded in the mold can be separately positioned and set, and the molding and the bonding can be performed simultaneously. FIG. 3 shows steps 7 and 8 as 1
An example in which one process is performed is shown. In the figure, a protrusion 9 is also formed on the upper surface of the resin layer 1. By the arrangement of the protrusions 9, the pressurizing portion in the bonding step (step 7) can be selectively set. This enables uniform pressurization.

In this embodiment, an epoxy resin material is used as a material for the resin layer 3, but a thermoplastic resin such as a polyphenylene resin may be used. Also, the resin layer 2
In order to obtain good thermal conductivity, a structure containing an inorganic material filler (for example, alumina, magnesia, silica, beryllia, zirconia, silicon nitride, aluminum nitride, silicon carbide, etc.) having a content of 50% by volume or more is required. Is desirable. On the other hand, if the filler is contained in an excessively large amount, minute voids are likely to be generated in the resin layer 2. Therefore, the content of the filler is preferably 95% by volume or less.

In this embodiment, an example of a semiconductor device using an IGBT element as the power semiconductor element 11 has been described. However, another type of semiconductor element such as a MOS transistor or a diode may be used. Furthermore, a specific circuit formed by a combination of these plural elements, for example, an inverter power module may be used. Further, a passive element such as a resistor or a capacitor may be included in the circuit.

(Embodiment 2) FIG. 4 shows another embodiment of the present invention having a structure substantially similar to that of Embodiment 1. The difference from the first embodiment is as follows. That is, the structure is such that the spacers 7 of alumina balls are arranged in place of the protrusions 8 formed by the resin layer 1 of the first embodiment.

In step 7 of a series of manufacturing steps shown in FIG. 2, a plurality of alumina balls having a diameter of 0.15 mm are arranged on the surface of the green resin sheet, and the main surface 2 of the primary molded lead frame is thermocompression-bonded. Then, the structure of this embodiment can be realized by bonding the two. In the present embodiment, the example of the alumina ball is shown as the material of the spacer 7.
Other insulating materials such as magnesia, silica, beryllia,
It may be an inorganic material such as zirconia, silicon nitride, aluminum nitride, or silicon carbide, and the shape is not limited to a sphere. The diameter of the sphere is substantially the same as the required thickness of the resin layer 2.

(Embodiment 3) Another embodiment of the present invention having substantially the same structure as that of the embodiment 2 is shown in FIG. The difference from the second embodiment is as follows. That is, it has a structure in which a plurality of the spacers 7 of the second embodiment are arranged in advance inside the resin layer 2.

In step 7 in the series of manufacturing steps shown in FIG. 2, in the process of producing the green resin sheet, a plurality of alumina balls having a diameter of 0.15 mm are prepared in advance in the sheet and the primary sheet is prepared. The structure of the present embodiment can be realized by thermocompression bonding the other main surface side of the molded lead frame and bonding them together. In this embodiment, the spacer 7
Although an example of an alumina ball has been shown as a material for the above, an inorganic material such as magnesia, silica, beryllia, zirconia, silicon nitride, aluminum nitride, and silicon carbide may be used, and the shape is not limited to a sphere.

(Embodiment 4) FIG. 6 is a circuit block diagram of a home air conditioner to which a semiconductor device according to any of the embodiments of the present invention is applied. In the drawing, a motor 3 for driving the compressor is shown.
The semiconductor device according to the present invention is applied to a switching circuit for controlling the power supply. FIG. 7 shows details of the switching circuit section. In the figure, terminals P and N are connected to a power supply circuit. With the air conditioner having this configuration, a switching circuit portion having low heat resistance and high reliability can be obtained, and an energy-saving air conditioner can be provided.

FIG. 8 shows a cross-sectional configuration diagram of the present switching circuit section. Six IGBTs as power semiconductor elements 11
And a main circuit is formed on the electrode plate 13 of the lead frame, and a control circuit including the driver IC 19 is formed on the resin substrate 21. Resin substrate 21 is also IGB
It is mounted on an electrode plate portion 13 different from the T portion, and is covered with the resin layer 1. The present semiconductor device is used by being attached to a heat sink 20. The externally exposed surface of the metal substrate 6 that is not covered with the resin contacts the heat sink surface, and the heat generated by the IGBT is radiated through the contact surface.

By applying the configuration of this embodiment to other electric equipment having a motor, such as a household or industrial use, such as a refrigerator, a freezer, a pump, and a transporter, it is possible to realize an energy-saving electric equipment. it can.

[0026]

According to the present invention, a resin-encapsulated semiconductor device having high reliability and low thermal resistance can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional configuration view of a power semiconductor device according to an embodiment of the present invention.

FIG. 2 is a manufacturing process diagram of the embodiment of FIG. 1;

FIG. 3 is a sectional configuration diagram of a power semiconductor device according to another embodiment of the present invention.

FIG. 4 is a sectional configuration diagram of a power semiconductor device according to another embodiment of the present invention.

FIG. 5 is a sectional configuration diagram of a power semiconductor device according to another embodiment of the present invention.

FIG. 6 is a circuit block diagram of an air conditioner according to an embodiment of the present invention.

FIG. 7 is a circuit block diagram of an air conditioner switching unit according to an embodiment of the present invention.

FIG. 8 is a cross-sectional configuration diagram of an air conditioner switching unit according to an embodiment of the present invention.

[Explanation of symbols]

1, 2, 3 ... resin layer, 4, 5 ... lead electrode part of lead frame, 6 ... base substrate, 7 ... spacer, 8 ... protrusion a, 9 ... protrusion b, 11 ... power semiconductor elements a, 12 ...
Power semiconductor elements b, 13: Lead frame electrode plate part, 14: Solder layer, 15: Wire bonding part, 1
6 ... resin insertion opening, 17 ... upper mold, 18 ... lower mold, 19 ...
Driver IC, 20 heat sink, 21 resin board.

Continued on the front page (72) Inventor Masahiro Goda 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Noritaka Kamimura 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture F-term in Hitachi Research Laboratory, Hitachi, Ltd. (Reference) 4M109 AA02 BA02 CA21 DB02 DB15 EB11 5F067 AA03 AA19 CA01 DE04

Claims (7)

[Claims] A semiconductor element; an electrode plate on which the semiconductor element is mounted; a lead electrode electrically connected to the semiconductor element; and a substrate on which the semiconductor element, the electrode plate, and the lead electrode are mounted. And a first resin layer covering the semiconductor element, the electrode plate and the lead electrode, and between the electrode plate and the lead electrode and the substrate,
A structure having a second resin layer adhered to the electrode plate, the lead electrode and the substrate; and a third covering the structure so that a part of the lead electrode and a surface of the substrate are exposed. And a resin layer. 2. The semiconductor device according to claim 1, further comprising spacer means located in said second resin layer. 3. The semiconductor device according to claim 1, wherein the second resin layer contains 50% by volume to 95% by volume of an inorganic material-based filler. 4. A first step of mounting a semiconductor element on the electrode plate portion of a lead frame having an electrode plate portion and a lead electrode portion, wherein the semiconductor element, the electrode plate portion, and the lead electrode portion are firstly mounted. A second step of coating the lead frame with a resin layer, a third step of cutting the lead frame, a fourth step of pressing a substrate and the lead frame through a second resin layer, and a lead frame. , Semiconductor element, first and second resin layers,
And a fifth step of covering a structure including the substrate with a third resin layer. 5. The semiconductor device according to claim 4, further comprising a step of evaluating an electrical characteristic of the circuit including the semiconductor element between the third step and the fourth step. Manufacturing method. 6. The method according to claim 4, wherein in the second step, a projection is formed on the first resin layer, and in the fourth step, the projection is pressure-bonded to the substrate. A method for manufacturing a semiconductor device. 7. The method according to claim 4, wherein in the fourth step, a spacer is included in the second resin layer.