JPH08298299A - Semiconductor device - Google Patents

Abstract

(57) [Summary] [Structure] The circuit part including the power semiconductor element is integrally reinforced by a resin mold of a material having a specified thermal expansion coefficient. [Effect] A compact and high-density semiconductor device can be provided at a low price.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device in which a chip component including a semiconductor element is mounted on a substrate and electrically connected to a conductor circuit, and in particular, a power semiconductor element as an active element is fixed to the semiconductor device. The present invention relates to a hybrid integrated circuit power semiconductor device in which the reliability of an insulating layer on a metal base substrate is improved.

[0002]

2. Description of the Related Art The conventional power semiconductor device of this type has the following two configurations. One is disclosed in Japanese Patent Laid-Open No. 62-2587. This is a wiring board in which a resin-based insulating layer and a conductor pattern are formed on a metal plate. A predetermined circuit is formed by fixing a power semiconductor element or the like on this conductor pattern, and has a structure filled with a gelled silicone resin. In a wiring board having this structure, a uniform and flat insulating layer can be arranged on the surface of the metal plate.Therefore, a non-insulated power semiconductor element having a collector electrode at the bottom should be directly fixed via a conductor layer such as a heat spreader. Therefore, there is a high degree of freedom in design when arranging conductor wiring, and it is effective for high density or miniaturization. However, it has the following drawbacks. Since the resin layer is interposed between the power semiconductor element and the metal base substrate, the thermal resistance increases as the resin layer becomes thicker. On the other hand, normally used layer thickness 1
When the thickness is reduced to about 00 μm or less, the internal stress at the time of temperature change due to the difference in thermal expansion coefficient between the semiconductor element and the metal base substrate is concentrated on the resin layer, and cracks or the like are likely to occur to easily deteriorate the insulation characteristics. There is a phenomenon.

The other one is disclosed in JP-A-64-42160 and JP-A-6-80748. That is, a power semiconductor element is set in advance on a metal base substrate with a predetermined gap, and a resin is poured as a mold layer including the gap to form a semiconductor device. According to this structure, since there are many resin layers as a structure surrounding the semiconductor element, cracks due to stress concentration are less likely to occur and high reliability as an insulating layer can be obtained. However, as described above, this is a method in which the resin is poured into the space in which the elements are set in advance, and the thickness of the resin layer tends to become unstable. Usually, the thermal conductivity of this kind of resin layer is extremely low, and a slight error in the layer thickness causes a large variation in thermal resistance, and it is difficult to obtain stable quality in a mass production factory.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to realize a highly reliable and compact power semiconductor device. That is, by applying a so-called insulating metal substrate on which an insulating layer is formed in advance, an insulating layer having a uniform and stable layer thickness can be arranged under the power semiconductor element, and a large amount of resin layer is arranged around the semiconductor element. Thus, the stress concentration on the insulating layer when the temperature changes as described above is relaxed, and as a result, a highly reliable and compact power semiconductor device is provided.

Another object of the present invention is to provide a structure suitable for heat dissipation required for a practical power semiconductor device and having a stable thermal resistance easily and at low cost.

[0006]

In order to achieve the above object, the present invention takes the following means.

(1) An active element and / or a passive element fixed on the insulating layer of an insulating metal substrate in which at least one surface of the metal substrate is previously coated with an organic insulating layer,
In a power semiconductor device having a conductor circuit for electrically connecting it and an input / output terminal with the outside, and the circuit system is protected by a resin mold, the resin mold is integrally configured. The semiconductor device is configured such that the mold is substantially composed of a single resin layer.

(2) In (1), the active element is
The semiconductor device is composed of a non-insulated power semiconductor element.

(3) In (1) or (2), the ratio of the coefficient of thermal expansion at a normal operating environment temperature is such that the organic insulating layer has a maximum of 1.2 and a minimum of 0.5 with respect to the metal substrate. The semiconductor device is adjusted to the range.

(4) In (1) or (2), the ratio of the coefficient of thermal expansion at a normal operating environment temperature is such that the resin-based mold has a maximum of 1.5 and a minimum of 0.5 with respect to the organic insulating layer.
The semiconductor device is adjusted to the range of.

(5) In (1) or (2), the ratio of the coefficient of thermal expansion at a normal operating environment temperature is such that the resin-based mold has a maximum of 1.2 and a minimum of 0.5 with respect to the metal substrate. The semiconductor device is adjusted to.

(6) In (1) or (2), the ratio of the coefficient of thermal expansion at the normal operating environment temperature is such that the organic insulating layer has a maximum of 1.2 and a minimum of 0.5 with respect to the metal substrate. ,
In addition, the semiconductor device is such that the resin-based mold is adjusted to a maximum range of 1.2 and a minimum range of 0.5.

(7) In (1) or (6), the semiconductor device is such that the metal substrate is composed mainly of aluminum or copper.

(8) In (1) or (7), the resin-based mold contains at least two of epoxy resin, phenol resin, antimony trioxide, epoxysilane, epoxy-modified siloxane, aluminum oxide, and silicon oxide. A semiconductor device is constituted by including as an active ingredient.

(9) In (1) or (8), a chip part for a control system circuit for driving the power semiconductor element on the insulating metal substrate and / or a chip for a protection system circuit for monitoring overcurrent, overtemperature, etc. A semiconductor device including components is used.

[0016]

The function of the present invention is as follows.

(1) An active element and / or a passive element fixed on the insulating layer of an insulating metal substrate, at least one surface of which is preliminarily covered with an organic insulating layer, and a conductor circuit for electrically connecting it In a power semiconductor device having a structure having an external input / output terminal and a circuit system protected by a resin mold, the resin mold is integrally configured, and the mold is substantially a single resin layer. Since it is composed of so-called hard resin, a uniform and flat insulating layer can be arranged on the surface of the metal plate, and a non-insulated power semiconductor element with a collector electrode at the bottom can be directly fixed via a conductor layer such as a heat spreader. Therefore, there is a high degree of freedom in design when arranging conductor wiring, and it is effective for high density or miniaturization. Furthermore, since the entire circuit including the power semiconductor element is covered with the single mold resin layer, the organic insulating layer is reinforced and stress concentration on the insulating layer can be relaxed. Usually, as a material property required for this organic insulating layer, there is a good thermal conductivity in addition to a sufficient electric insulating property. To achieve this, a large amount of filler is generally contained inside. Therefore, it can be said that the structure is likely to cause cracks due to stress. On the other hand, regarding the molding resin, it is not necessary to give special consideration to the thermal conductivity, and the degree of freedom in selecting the material is high. Therefore, a stress resistant material can be selected. By reinforcing the organic insulating layer with this material, it is possible to suppress the occurrence of cracks and the like due to the difference in thermal expansion coefficient from silicon.

(2) In (1), the active element can be directly fixed on the metal substrate on which the insulating layer is formed in advance.
A non-insulated type power semiconductor device can be applied. Therefore, general-purpose power elements such as power transistors and IGBTs can be mounted without being limited to the insulating type.

(3) In (1) or (2), the ratio of the coefficient of thermal expansion at the normal operating environment temperature is such that the organic insulating layer has a maximum of 1.2 and a minimum of 0.5 with respect to the metal substrate. Since the temperature is adjusted, the internal stress caused by the difference in the coefficient of thermal expansion between the metal substrate and the organic insulating layer when the temperature changes is relaxed. Therefore, it is possible to suppress warpage of the entire substrate or local stress concentration even by repeated heat loads such as a heat cycle test assuming an actual use environment.

(4) In (1) or (2), the ratio of the coefficient of thermal expansion at a normal operating environment temperature is such that the resin-based mold has a maximum of 1.5 and a minimum of 0.5 with respect to the organic insulating layer. Therefore, the internal stress due to the difference in thermal expansion coefficient between the organic insulating layer and the resin-based mold layer is relaxed. Therefore, it is possible to suppress warpage of the entire substrate or local stress concentration even by repeated heat loads such as a heat cycle test assuming an actual use environment.

(5) In (1) or (2), the ratio of the coefficient of thermal expansion at a normal operating environment temperature is within the range of 1.2 for resin molds and 0.5 for metal bases. Since it is adjusted, the internal stress caused by the difference in the coefficient of thermal expansion between the metal substrate and the resin-based mold layer is relaxed. Therefore, it is possible to suppress warpage of the entire substrate or local stress concentration even by repeated heat loads such as a heat cycle test assuming an actual use environment.

(6) In (1) or (2), the ratio of the coefficient of thermal expansion at a normal operating environment temperature is such that the organic insulating layer has a maximum of 1.2 and a minimum of 0.5 with respect to the metal substrate. ,
In addition, since the resin-based mold is adjusted to a maximum range of 1.2 and a minimum range of 0.5, the internal stress caused by the difference in the thermal expansion coefficient between the metal substrate-organic insulating layer-resin-based mold layer is relaxed. Therefore, it is possible to suppress warpage of the entire substrate or local stress concentration even by repeated heat loads such as a heat cycle test assuming an actual use environment.

(7) In (1) or (6), the metal substrate is composed mainly of aluminum or copper. These materials have good thermal conductivity, good heat dissipation,
Material prices are also low.

(8) In (1) or (7), the resin mold is epoxy resin, phenol resin, antimony trioxide, epoxysilane, epoxy-modified siloxane,
By including at least two of aluminum oxide and silicon oxide as an active ingredient, the thermal expansion coefficient can be adjusted to a preferable range. Further, it can satisfy the basic properties generally required for molding resins such as moldability and moisture resistance.

(9) In (1) or (8), a chip part for a control system circuit for driving a power semiconductor element and / or a chip part for a protection system circuit for monitoring overcurrent, overtemperature and the like are mounted on an insulating metal substrate. By including it,
The function as an inverter can be structurally integrated. Therefore, the wiring length between components can be shortened to the minimum, and the device can be downsized and noise can be reduced.

[0026]

EXAMPLES The present invention will now be described in more detail by way of examples.

(Embodiment 1) FIG. 1 is a sectional view showing an embodiment of the present invention. For example, IGBT (Insulated Gate Bip
A power semiconductor element 11 such as an orange transistor is fixed on the conductor pattern 13 via the heat spreader 12. The power semiconductor device having this structure is manufactured by the following steps. An epoxy-based insulating layer 14 having a thickness of 100 μm is thermocompression-bonded to one surface of a metal base substrate 15 having a thickness of 2.5 mm, a width of 55 mm, and a length of 72 mm, which is mainly composed of aluminum, to produce an insulating substrate. For the purpose of improving the thermal conductivity of the insulating layer 14, at least 60 vol% of filler such as alumina or silicon oxide is contained. A copper conductor layer is formed on the insulating layer of the metal substrate by plating or thermocompression. This copper conductor layer is selectively removed by etching to form a conductor pattern 13 having a predetermined shape.

On the other hand, the power semiconductor element 11 is joined to the heat spreader 12 made of a copper chip with a high temperature solder 21 such as 95Pb-5Sn. This joining member is fixed on a conductor pattern prepared in advance with a low temperature solder 20 such as 60Sn-40Pb. At this time, other chip parts such as capacitors and resistors necessary for forming a circuit and the output terminal 16 and the input terminal 17 may be simultaneously joined.

The series of circuits prepared in this step is set in a mold set to a predetermined temperature and a resin mold 18 is molded by an injection method to obtain a power semiconductor device according to the present invention. In this example, Table 1 was used as the material of the mold 18.

[0030]

[Table 1]

The blending ratios in Table 1 are shown by weight ratio.

For comparison, a conventional power semiconductor device is shown in FIG. In the structure according to the conventional method, the mold case 22, the terminal block 23 and the like need to be individually manufactured, and in addition, many steps such as filling and curing of the gel 24 are required as compared with the present invention. (Example 2) Under the same conditions as in Example 1, the materials of the insulating layer 14 and the resin mold 18 were changed to prepare a plurality of samples having different thermal expansion coefficients, and the metal base substrate 15 in the initial state of these samples was prepared. The amount of warp was evaluated. The results are shown in Table 2.

[0033]

[Table 2]

The amount of warpage was measured by a three-dimensional digital position measuring device and expressed as the absolute value of the difference between the lowest point and the highest point. If the warp is large, the thermal resistance with the cooling fins 35 increases, which poses a practical problem. Therefore, the maximum allowable warp is 80.
μm. From the results in Table 2, the range of preferable thermal expansion coefficients of the insulating layer 14 and the resin mold 18 corresponding to the metal base substrate 15 was obtained.

(Embodiment 3) Both the power semiconductor device having the structure shown in FIG. 1 according to the present invention manufactured in Embodiment 1 and the structure shown in FIG. 2 manufactured under substantially the same conditions except for the resin mold 18 are targeted. As a result, an attempt was made to compare reliability by the following heat cycle test. Conditions are 125 ° C 60 minutes -25 ° C
30 minutes-under zero 40 ° C 60 minutes-25 ° C 30 minutes. Evaluation is based on the metal base substrate 15 and the conductor pattern 13.
The change with time of the breakdown limit voltage during the period was measured. The result is shown in FIG. With the conventional method, the breakdown voltage drops sharply when the number of repetitions exceeds 300 cycles. On the other hand, according to the present invention, 2 kV is obtained even after 2000 cycles.
The above has been maintained and is in a practical area. In order to know the cause of this, the cross sections of both samples were observed by SEM. As a result, in the conventional method, generation of fine cracks was observed in the insulating layer 14 immediately below the semiconductor chip.
This crack is considered to be the cause of the decrease in breakdown voltage.

As a result of the internal stress simulation by the finite element method, the following was found. According to the conventional method,
A difference in the coefficient of thermal expansion between the semiconductor element 11 formed of a silicon chip and the metal base substrate 15 causes a difference in the amount of dimensional change due to a temperature change. As a result, a stress concentration part is generated in the insulating layer 14 at a position intermediate between the two materials. However, in the structure according to the present invention, the periphery of the semiconductor element 11 is
Since the metal base substrate 15 and the resin mold 18 having a small difference in thermal expansion coefficient from each other are covered, the occurrence of such stress concentration portions is significantly suppressed.

(Embodiment 4) An inverter was prototyped based on the power semiconductor device according to the present invention of Embodiment 1 shown in FIG. The cross-sectional view is shown in FIG. 4 and the circuit block diagram is shown in FIG. In this embodiment, in addition to the configuration shown in FIG. 1, a gate driving IC 31, a smoothing capacitor 32, a rectifying circuit capacitor bridge 33, etc. are added, and a control microcomputer, a power supply circuit 34, etc. are added to form an inverter module. It is a thing.

It was confirmed that the prototype inverter was connected to a three-phase induction motor to obtain good characteristics. It was also found that reliability is high due to repeated use with temperature changes.

[0039]

As described above, the present invention has the following effects.

(1) Since the power semiconductor device 11 is fixed onto the homogeneous and thin organic insulating layer 14 and the whole is reinforced by the resin mold 18, low thermal resistance and high reliability are achieved at the same time. To be realized.

(2) As the power semiconductor element 11, not only an insulating type but also an non-insulating type power element can be applied, which has a high degree of freedom in terms of circuit configuration, and is easy to be miniaturized and highly integrated.

(3) Coefficient of thermal expansion 1 of the metal base substrate 15
On the other hand, since the organic insulating layer 14 has a thickness in the range of 1.2 to 0.5, the internal stress when the temperature changes is suppressed.

(4) Since the resin mold layer 18 has a coefficient of thermal expansion of 1 in the range of 1.5 to 0.5 with respect to the coefficient of thermal expansion of the organic insulating layer 14, the internal stress when the temperature changes is suppressed.

(5) Coefficient of thermal expansion 1 of the metal base substrate 15
On the other hand, since the resin mold layer 18 has a thickness in the range of 1.2 to 0.5, the internal stress when the temperature changes is suppressed.

(6) Coefficient of thermal expansion 1 of the metal base substrate 15
On the other hand, since the resin mold layer 18 has a thickness in the range of 1.2 to 0.5, the internal stress when the temperature changes is suppressed.

(7) Since the material for the metal base substrate 15 is mainly composed of aluminum or copper, low thermal resistance and low price are realized.

(8) Since the resin mold material contains two of epoxy resin, phenol resin, antimony trioxide, epoxysilane, epoxy-modified siloxane, aluminum oxide, and silicon oxide, the thermal expansion coefficient of the present invention is the same as that of the present invention. It can be adjusted to a preferable range and realizes the basic characteristics required for moldability and resin molding.

(9) There is an effect of realizing a compact and high-density inverter module, and for example, an inverter having a structure integrated with a motor can be obtained.

[Brief description of drawings]

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

FIG. 2 is a sectional view of a power semiconductor device having a conventional configuration.

FIG. 3 is a comparison diagram of breakdown limit voltages.

FIG. 4 is a sectional view of an inverter module according to an embodiment of the present invention.

FIG. 5 is a circuit block diagram of an inverter module according to an embodiment of the present invention.

[Explanation of symbols]

11 ... Power semiconductor element, 13 ... Conductor pattern, 14 ...
Insulating layer, 15 ... Metal base substrate, 16 ... Output terminal, 17
Input terminals, 18 resin molds, 19 bonding wires, 20 low temperature solders, 21 high temperature solders.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masahiro Goda, Inventor Masahiro Goda 7-1, Omika-cho, Hitachi-shi, Ibaraki Hitachi Research Laboratory, Hitachi, Ltd. 1-1 Hitachi Ltd. Hitachi Research Laboratory (72) Inventor Kazuhiro Suzuki Kazuhiro Suzuki 1-1-1 Omika-cho, Hitachi City, Ibaraki Hitachi Ltd. Hitachi Research Laboratory (72) Inventor Motonobu Hattori Narashino Chiba Prefecture 7-1-1 Higashi Narashino, Higashi Narashino Industrial Equipment Division, Hitachi, Ltd. (72) Inventor Hiroyuki Hanai 7-1-1 Higashi Narashino, Narashino, Chiba Prefecture Industrial Equipment Division, Hitachi, Ltd.

Claims (9)

[Claims] 1. An active element and / or a passive element fixed on the organic insulating layer of an insulating metal substrate, at least one surface of which is precoated with an organic insulating layer.
In a power semiconductor device having a conductor circuit for electrically connecting it and an input / output terminal with the outside, and the circuit system is protected by a resin mold, the resin mold is integrally configured. A semiconductor device, wherein the mold comprises a substantially single resin layer. 2. The semiconductor device according to claim 1, wherein the active element is a non-insulated power semiconductor element. 3. The ratio of the coefficient of thermal expansion at a normal operating environment temperature is in the range of maximum 1.2 and minimum 0.5 of the organic insulating layer with respect to the metal substrate according to claim 1 or 2. Adjusted semiconductor device. 4. The resin mold according to claim 1 or 2, wherein the ratio of the coefficient of thermal expansion at a normal operating environment temperature is 1.5 at the resin mold and 0.5 at the minimum.
A semiconductor device adjusted to a range of 5. 5. The resin mold according to claim 1, wherein the ratio of the coefficient of thermal expansion at a normal operating environment temperature is 1.2 at the maximum and 0.5 at the minimum with respect to the metal substrate.
Device adjusted to the range of. 6. The ratio of coefficient of thermal expansion at a normal operating environment temperature in the claim 1 or claim 2 is such that the organic insulating layer has a maximum of 1.2 and a minimum of 0.5 with respect to the metal substrate. A semiconductor device in which the resin mold is adjusted to a maximum range of 1.2 and a minimum range of 0.5. 7. The semiconductor device according to claim 1 or 6, wherein the metal substrate is composed mainly of aluminum or copper. 8. The resin mold according to claim 1 or 7, wherein at least two of epoxy resin, phenol resin, antimony trioxide, epoxysilane, epoxy-modified siloxane, aluminum oxide and silicon oxide are used. A semiconductor device containing an active ingredient. 9. The chip component for a control system circuit for driving the power semiconductor device and / or the chip component for a protection system circuit for monitoring overcurrent, overtemperature, etc. according to claim 1 or 8. A semiconductor device configured to include.