JP2864992B2 - Hybrid integrated circuit device and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid integrated circuit device in which a high power semiconductor device is used as a component on a circuit.

[0002]

2. Description of the Related Art As a conventional integrated circuit device in which a high-power semiconductor element is used as one constituent element on a circuit, there is one disclosed in, for example, Nippon Denso Publication Technical Report No. 24-095. This circuit device has a structure in which a high-power semiconductor element is fixed to a metal case so as to improve heat radiation characteristics.

FIG. 5 shows this hybrid integrated circuit device.
As shown in (1), the high-power semiconductor element 1 and the pedestal 2, the pedestal 2 and the alumina substrate 3, the alumina substrate 3 and the metallic envelope 4 can be soldered respectively, and the thermal conductivity and the heat radiation characteristics are good. I have. Also, an alumina substrate 3 and a metallic envelope 4
May have a structure of bonding with an adhesive. Here, the pedestal 2 is made of a metal (for example, copper) having good thermal conductivity, and the alumina substrate 3 has a metal film which can be soldered on both sides or one side thereof by a thick film conductor printing method or a metallizing method. . The metallic envelope 4 is made of aluminum die cast or the like in consideration of the mountability and thermal conductivity of the hybrid integrated circuit device.

[0004]

As an insulating plate such as an alumina substrate of a semiconductor device including a high-power semiconductor element, a thick insulating substrate formed with an Ag conductor has been generally used. . As another known insulating substrate of this type, there is an insulating substrate formed by tungsten metallization.

However, in the case of a thick film substrate in which the Ag conductor is printed and baked, Ag grows rapidly in an alloy layer with Sn or the like contained in the solder at the time of soldering at the time of assembling. At a temperature of 260 ° C. or higher at which the high-temperature solder on the joint side surface is reflow-assembled, a stable soldering state cannot be secured because the growth of the alloy layer of Ag and Sn becomes extremely fast. For this reason, the soldering process must be divided into two, that is, soldering of the bonding surface side of the high power semiconductor element and soldering of the Ag thick film insulating substrate. Moreover,
There is a concern that the growth of the alloy layer described above may further progress depending on the usage environment of the semiconductor device.

Referring to FIG. 6, an Ag paste is printed on one surface 3a of the alumina substrate 3 and baked to form an Ag conductor 10 on the surface 3a of the alumina substrate 3. When a solder Pb-Sn based alloy is placed on the surface of the Ag conductor 10 and reflowed at a high temperature of 260 ° C. or higher, a Sn alloy layer in the solder Pb—Sn grows, and this alloy layer hinders soldering. There is a problem.

On the other hand, the above-mentioned tungsten metallized insulating substrate is considered as one means for eliminating the instability of the soldering state in the case of the high-temperature solder reflow. In this case, for example, as shown in FIG.
2 are formed by simultaneous firing. On the surface of one tungsten layer 11, a Ni plating layer 13 is formed, and on the surface of the other tungsten layer 12, an insulating film 14 is formed.
The Ni plating layer 13 is formed to enable soldering, and the insulating film 14 is formed to enhance adhesion to a metal case. However, according to this tungsten metallized substrate, a complicated surface treatment such as formation of the tungsten layers 11 and 12, the Ni plating layer 13 and the insulating film 14 on both surfaces of the alumina substrate 3 results in an increase in cost. There is.

An object of the present invention is to provide a hybrid integrated circuit device which can be manufactured at low cost with stable soldering.

[0009]

According to a first aspect of the present invention, there is provided a hybrid integrated circuit device for an internal combustion engine according to the present invention, wherein C is provided between a conductive case and a high-power semiconductor element.
An insulating plate having a u-thick film is provided , and the high power is applied to the Cu thick film.
High temperature solder reflow at 260 ° C or higher
-It is characterized by being obtained by assembling .
3. The hybrid integrated circuit according to claim 2, wherein a heat sink is interposed between the high-power semiconductor element and the insulating plate, and between the high-power semiconductor element and the heat sink and between the heat sink and the insulating plate. Are soldered . According to a third aspect of the present invention, in the hybrid integrated circuit device, the Cu thick film is formed on one surface of the insulating plate.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a hybrid integrated circuit device, wherein a portion between the high power semiconductor element and the heat sink and a portion between the heat sink and the insulating plate are simultaneously soldered.

[0011]

According to the hybrid integrated circuit device of the first aspect of the present invention, an insulating plate having a Cu thick film is provided between the conductive case and the high-power semiconductor element. Since an alloy layer that makes soldering unstable is not created in the solder, there is an effect that a hybrid integrated circuit device with stable soldering can be obtained. A stable solder reflow between the high-power semiconductor element and the insulating plate is enabled, and a stable bonding state can be ensured both during manufacturing and during use.

According to the hybrid integrated circuit device of the second aspect, since the heat sink is interposed between the high-power semiconductor element and the insulating plate, the heat dissipation by the heat sink is good. It is suitable as a circuit device for a high-power semiconductor element that generates a large amount of heat. According to the hybrid integrated circuit device of the third aspect, by forming the Cu thick film on one surface of the insulating plate, it is easy to bond the one surface to the conductive case on the opposite surface.

According to the method of manufacturing a hybrid integrated circuit device of the present invention, since the high power semiconductor element and the heat sink and between the heat sink and the insulating plate are simultaneously soldered, the circuit device is manufactured in one step. Therefore, there is an effect that the process cost can be reduced.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. As the insulating plate of the semiconductor device including the high-power semiconductor element according to the present invention, a thick film substrate obtained by printing and firing a Cu conductor (hereinafter referred to as “Cu thick film substrate”) is used. this is,
If a Cu conductor is formed on the insulating plate, a product that makes soldering unstable becomes less likely to be generated due to the slow growth of an alloy layer such as Sn contained in the solder when soldering in a subsequent process. It utilizes the property of stabilizing soldering.

In FIG. 1, 1 is a high power semiconductor device,
For example, it is an element for driving a large current used in an igniter of an ignition device for an internal combustion engine. Reference numeral 20 denotes a heat sink made of a metal having good thermal conductivity, for example, Mo, and reference numeral 21 denotes an alumina substrate, which is formed by printing and firing Cu on one surface 21a. 4 is a metal having good thermal conductivity, for example, A
This is a metallic case as a conductive case made of l, Cu, or the like. In FIG. 1, reference numerals 23 and 24 denote solder, and 25
Is a Si-based adhesive.

The structure of the Cu thick film substrate is shown in FIG.
It is as shown in. One side 21 of alumina substrate 21
The Cu conductor 26 is formed on a. This Cu conductor 26
Is formed by printing and baking a Cu paste on one surface 21a of the alumina substrate 21. When manufacturing the semiconductor device, solder is placed on the surface of the Cu conductor 26 and soldered to the heat sink 20.

Next, an example (1) and another example (2) of a manufacturing process of a semiconductor device including a high-power semiconductor element will be described with reference to FIGS. The manufacturing process (1) shown in FIG. 3 is for a single assembly reflow. The semiconductor device 30 is obtained by combining the high-power semiconductor element 1, the solder 23, the heat sink 20 as a heat sink, the solder 24, and the insulating plate 21 and keeping them at a high temperature and keeping them at a temperature at which the solder melts. Can be Thereafter, the semiconductor device 30 is bonded to the metallic case 4 or the like with a Si-based adhesive 25 or the like as shown in FIG.

The manufacturing process (2) shown in FIG. 4 is an example in the case of two reflows. First, the semiconductor device 32 is formed by first reflowing the high-power semiconductor element 1, the solder 23, and the heat sink 20 at the first temperature T ₁ to form a semiconductor device 32. At the same time, the semiconductor device 33 is obtained by performing a second reflow at a _second temperature T ₂ (T ₂ <T ₁ ) and soldering. Semiconductor device 3
3 is similar to the semiconductor device indicated by reference numeral 30 shown in FIG. The semiconductor device 33 is fixed to a metal case or the like on one surface of the insulating plate 21 by an adhesive.

In the manufacturing process (1), the high-power semiconductor element 1, the heat sink 20, and the insulating plate 21 can be simultaneously fired and fixed in one step, so that the process cost can be reduced. this
In the example of the manufacturing process (1), compared to the example of the manufacturing process (2), firing can be performed without having to divide the soldering process into two, and since each solder can be reflowed simultaneously, cost reduction is effective. is there.

In the manufacturing process (2), the first reflow is fired at a high temperature T ₁ , and the second reflow is fired at a low temperature T 1.
_Since it is performed in step 2, there is an advantage that an appropriate soldering step for each temperature can be performed by two firings by two operations. According to the present embodiment, since the growth of the Sn-based alloy layer that deteriorates the soldering characteristics of the Cu thick film substrate is slow, a stable soldering state can be maintained regardless of the use environment.

Further, when the high power semiconductor device according to the present embodiment is applied to a device which drives a large current such as an igniter, the heat sink 20 and the metal case 4 can effectively maintain good heat radiation. There is. The heat conductivity of the heat sink 20 is good because molybdenum is used, and the metal case 4 is good in heat conductivity and heat radiation because it uses aluminum.

Further, in this embodiment, the heat sink 20 has an effective heat radiation function in an abnormal transient state in which the igniter keeps on, for example. In addition, the metal case 4 performs an effective heat radiation action in a steady state.
In the present invention, the bonding between the insulating plate and the metallic case may be performed with an adhesive other than the Si-based adhesive, or may be performed by soldering instead of bonding with the adhesive. Further, in the present invention, a structure in which the heat sink indicated by reference numeral 20 in FIG. 1 may be omitted.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a hybrid integrated circuit device according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view showing a structure of an insulating plate before bonding according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing an example of a manufacturing process for manufacturing the hybrid integrated circuit device shown in FIG.

FIG. 4 is an explanatory view showing another example of the manufacturing process for manufacturing the hybrid integrated circuit device shown in FIG. 1;

FIG. 5 is a schematic sectional view showing a hybrid integrated circuit device according to the prior art.

FIG. 6 is a schematic sectional view showing an example of a conventional alumina substrate.

FIG. 7 is a schematic cross-sectional view showing another example of the alumina substrate of the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 High power semiconductor element 4 Metallic case (conductive case) 20 Heat sink 21 Alumina substrate (insulating plate) 23, 24 Solder 25 Si adhesive 26 Cu conductor

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-273155 (JP, A) JP-A-2-7454 (JP, A) JP-A-4-15091 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) H01L 23/12 H01L 25/04

Claims (4)

(57) [Claims] An insulating plate having a Cu thick film is provided between a conductive case and a high-power semiconductor element , and the Cu thick film has
For high-power semiconductor devices, solder at high temperatures of 260 ° C or higher.
A hybrid integrated circuit device for an internal combustion engine obtained by reflow assembly . 2. A heat sink is interposed between the high-current semiconductor device and the insulating plate, and the space between the high-power semiconductor device and the heat sink and the space between the heat sink and the insulating plate are soldered. 2. The hybrid integrated circuit device for an internal combustion engine according to claim 1, wherein: 3. The hybrid integrated circuit device for an internal combustion engine according to claim 2, wherein said Cu thick film is formed on one surface of said insulating plate. 4. A method for manufacturing a hybrid integrated circuit device for an internal combustion engine according to claim 2, wherein said high current semiconductor element and said heat sink are soldered simultaneously.