JPH05243289A - Hybrid integrted circuit device and its manufacture - Google Patents

Abstract

PURPOSE:To provide a hybrid integrated circuit capable of soldering of a very small size of semiconductor element and its manufacture. CONSTITUTION:This is one being plotted, seeking the ratio of the solder spread L and the height t after reflow in nitrogen atmosphere, as regards each kind of solder. It shows an extremely large L/t value in the range from 45:55 to 55:45 in the weight mixture ratio of tin to lead, as compared with the solder at mixture ratio beside the range. Accordingly, for the hybrid integrated circuit using the solder within the range from 45:55 to 55:45 in weight mixture ratio of tin to lead, being let reflow in nitrogen atmosphere, the solder flows enough even on a pad approximately 0.5mm in one side, and it hardens flatly. As a result, a very small size of semiconductor element is fixed horizontally.

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 and a method of manufacturing the same, and more particularly, to a technique for fixing minute semiconductor elements.

[0002]

2. Description of the Related Art Referring to FIG. 4, a conventional hybrid integrated circuit device includes an insulating metal substrate (20) and a die bond formed on the insulating metal substrate (20) with an insulating resin layer (22) in a predetermined shape. It is composed of circuit patterns such as pads (24) and (26), wire bonding pads (28), semiconductor elements (34) and (36) fixed to predetermined die bond pads (24) and (26), and the like.

Aluminum having a thickness of about 2 mm is used for the insulating metal substrate 20 in consideration of heat dissipation characteristics and workability, and the surface thereof is anodized to improve the insulating property. Die bond pads (24) (26), wire bonding pads (2
For the circuit pattern such as 8), a clad material made of a thermosetting insulating resin having adhesiveness such as polyimide resin and a copper foil having a thickness of about 35 μm is insulated at a temperature of 150 ° C. to 170 ° C. and a pressure of 50 to 100 Kg per square centimeter. After hot pressing on the metal substrate (20), the copper foil is photo-etched to form a predetermined pattern. In an actual hybrid integrated circuit device, in addition to the pattern described above, a conductive path such as a bus, a pad for fixing atypical parts such as a chip resistor or a chip capacitor, and an external lead pad for fixing an external lead of the hybrid integrated circuit device are provided. Simultaneously formed. In addition, the thermosetting insulating resin is completely cured in this hot pressing process to obtain approximately 3
The insulating resin layer 22 has a thickness of 5 μm.

The semiconductor elements (34) and (36) are used in a chip form, and are used for small signal transistors or integrated circuit elements, etc.
Small size semiconductor element (34) is fixed by using solder paste such as silver paste (30), and large size semiconductor element (36) such as high power transistor is fixed by using solder (32) .. The semiconductor elements (34) (36) are screen-printed with a creamy silver paste (30) and a solder (32) on a predetermined die bond pad (24) (26) in sequence, and by utilizing the viscosity, first, The large-sized semiconductor element (36) and odd-shaped components such as a chip resistor or a chip capacitor (not shown) are temporarily fixed and reflowed to be completely fixed. Then, the semiconductor element (34) of a minute size is similarly silver paste (30).
Temporarily fixed on top, reflowed and completely fixed.

Thereafter, the electrodes of the semiconductor elements (34) and (36) are wire-bonded to predetermined wire bonding pads (28), external leads (not shown) for external connection are fixed, and further, resin-made pads are used. The mounted element is sealed by the case.

[0006]

As described above, a technique for fixing a chip-shaped semiconductor element by solder reflow is already known. However, when soldering a small-sized semiconductor element of, for example, a small signal system onto the die bond pad using the reflow process, the following problems occur.

For example, a small signal transistor having a small size has a side of about 0.3 mm to 1.0 mm, and the size of the die bond pad (24) for this purpose is a side of 0.5 mm to 1.5 mm. .. The amount of solder that optimally fixes the semiconductor element on the die bond pad (24) needs to be about 0.018 to 0.025 mm ³ when one side of the chip size of the semiconductor element is 0.3 mm. On the other hand, the amount of the brazing material printed by the screen printing method is determined by the metal mask thickness, and it is difficult to print the brazing material to a thickness of 0.1 mm or less. This applies not only to printing but also to a dispenser method.

Therefore, when solder is applied to the die bond pad (24) having a fine size by means of printing or the like, excessive solder is printed or printed more than necessary to optimally fix the semiconductor element. This problem is a problem that cannot be solved by the current coating technology. As described above, in the conventional hybrid integrated circuit device in which the minute-sized semiconductor element is mounted, as shown in FIG. 4, the brazing material becomes excessive on the minute die bond pad (24), and the solder on the die bond pad (24) is At the time of reflow, the semiconductor element (34), which has a hemispherical shape due to the surface tension of the solder and is lightweight and extremely minute, is fixed while being inclined along the spherical surface of the molten solder. In this case, there is a problem that wire bonding cannot be performed and a complete failure occurs.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a hybrid integrated circuit device capable of solder-fixing a chip-shaped semiconductor element having an extremely small size onto a die bond pad. is there.

[0010]

[Means for Solving the Problems]
In order to achieve the object, a hybrid integrated circuit device according to the present invention is an insulative substrate, a circuit pattern formed in a predetermined shape on the insulative substrate, and a chip-shaped soldered on the circuit pattern. A hybrid integrated circuit device comprising a semiconductor element, wherein a tin / lead weight mixture ratio of solder for fixing the semiconductor element is tin / lead = 45/55 to tin / lead = 55.
The feature is that it is / 45.

Also, in the method for manufacturing a hybrid integrated circuit device according to the present invention, a circuit pattern having a predetermined shape is formed on an insulating substrate, and a tin / lead weight mixing ratio of tin / lead is set on the fixing pad of the circuit pattern. Lead = 45 / 55-tin / Lead = 55/45
It is characterized in that after applying the above-mentioned cream solder and mounting the chip-shaped semiconductor element on the fixing pad, a reflow process is performed in a nitrogen atmosphere to fix the semiconductor element on the fixing pad.

[0012]

In the hybrid integrated circuit device configured as described above, the solder having the tin / lead weight mixture ratio Sn / Pb = 45/55 to Sn / Pb = 55/45 is used for the small-sized semiconductor element. As a result of this fixing, the solder that is applied when the solder melts flows out evenly onto the fixing pad, and it is possible to fix the semiconductor element of minute size substantially flat.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS. The present invention is characterized by the composition of the solder and the reflow method for fixing the mounted element to the integrated circuit board, and it is impossible to use the conventional method as described in the section of the problem to be solved by the invention. It realizes the conventional hybrid integrated circuit structure. Therefore, FIG. 4 described above is used to describe the structure of the embodiment.

FIG. 1 is a wetting characteristic diagram in which the states of several kinds of solder after reflow are plotted, and FIG. 2 is a diagram for explaining a method of determining the state of solder after reflow. The experiment was 0.
Wide enough copper pattern using 1mm thick metal mask
(10) Solder cream is screen-printed on the surface, and the melting point temperature (liquidus temperature + 20
In order to improve the experimental accuracy, the ratio L / t of the spread L of solder (10) and the height t after reflow was used as a characteristic value in order to improve the experimental accuracy. ..

In the solder cream, the mixture ratio (weight ratio) of tin (Sn) and lead (Pb), which has been widely used for fixing integrated circuit elements or parts, is 10/90 and 63.
/ 37 types of two solder creams, mixing ratio (weight ratio) is 45
/ 55, 50/50, 55/45, 60/40, total 6 types of solder cream are used, for example, the mixing ratio is 63 /
The solder cream of 37 was 183 ° C., and the solder cream of 50/50 was reflowed in a nitrogen atmosphere at respective melting points (liquidus temperature + 20 to 30 ° C.) determined in advance such as 215 ° C.

As a result, as shown in FIG. 1, the mixing ratio (weight ratio) of tin (Sn) and lead (Pb) is 50/50.
According to the solder cream, the mixing ratio (weight ratio) is 10/90.
It was found that an L / t value of 500, which is several times that of the two conventional solder creams of 63 and 37, was obtained. Also, the L / t of solder cream with a mixing ratio of 45/55, 55/45
Although the value of the solder cream of 60/40 is the same as that of the conventional solder cream, the value is relatively large, so it is critical for the change of the mixing ratio of tin (Sn) and lead (Pb). It turned out that there is a tendency. A similar tendency was observed in reflow in air, but the L / t value was about 150 even with a 50/50 composition.

Here, referring again to FIG. 3, the hybrid integrated circuit device of the present invention and the manufacturing method thereof will be described. The hybrid integrated circuit device of the present invention, as shown in FIG.
(20), a circuit pattern formed with a die bonding pad (24) (26), a wire bonding pad (28), etc. in a predetermined shape via an insulating resin layer (22), and soldered to the die bond pad (24) (26) It has a structure including semiconductor elements (34), (36) and the like. Then, all the semiconductor elements (34) and (36) including the minute-sized semiconductor elements (34), which had to be fixed by using a brazing material such as silver paste, are tin (Sn) and lead (Pb). The first feature is that solder having a weight mixing ratio of 50) is used in a single reflow process and the reflow is performed in a nitrogen atmosphere at a temperature higher than the conventional reflow temperature. There are two characteristics.

Aluminum having a thickness of about 2 mm is used for the insulating metal substrate (20) in consideration of heat resistance, heat radiation characteristics and workability, and its surface is anodized to improve the insulating property. The circuit patterns of the die bond pads (24) (26), the wire bonding pads (28), etc. are made of a thermosetting insulating resin having adhesiveness such as polyimide resin and a clad material of approximately 35 μm thick copper foil at a temperature of 150 ° C. At 170 ° C, pressure of 50 to 100 kg per square centimeter, insulating metal substrate (2
After hot pressing to 0), the copper foil is photo-etched to form a predetermined pattern. In an actual hybrid integrated circuit device, in addition to the pattern described above, a conductive path such as a bus, a pad for fixing atypical parts such as a chip resistor or a chip capacitor, and an external lead pad for fixing an external lead of the hybrid integrated circuit device are provided. Simultaneously formed. Further, the thermosetting insulating resin is completely cured in this hot pressing process to form an insulating resin layer (22) having a thickness of about 35 μm.

Next, the weight mixing ratio is about 45/55 to 55.
/ 45 tin (Sn), lead (Pb) and a small amount of flux mixed solder cream is screen-printed on a predetermined die bond pad (24) (26) using a 0.1 mm thick metal mask, and solder All the semiconductor elements (34) and (36) are temporarily temporarily fixed by utilizing the viscosity of the cream. Then, the semiconductor elements 34 and 36 are completely fixed by reflowing at a temperature of about 215 ° C., which is higher than that of the conventional example. In the hybrid integrated circuit device of the present invention, although relatively high temperature reflow is required, since the metal substrate is used as the integrated circuit substrate, the heat resistance of the substrate is not limited.

[0020]

As described above, according to the hybrid integrated circuit device of the present invention, a micro-sized integrated circuit element which could not be horizontally fixed unless a relatively expensive brazing material such as silver paste was used. It can be fixed using inexpensive solder. Moreover, since soldering is performed similarly to other large-sized integrated circuit elements and parts, the screen printing process and the reflow process of the brazing material are simplified.

Further, since it is a single reflow, there is an advantage that all the integrated circuit elements and parts can be continuously temporarily fixed to the brazing material. Furthermore, since a metal substrate is used as the integrated circuit substrate, there is an advantage that the reflow temperature is not limited.

[Brief description of drawings]

FIG. 1 is a solder wetting characteristic diagram.

FIG. 2 is a sectional view of solder for explaining a method of determining the wetting characteristics.

FIG. 3 is a cross-sectional view of a main part of a hybrid integrated circuit device that employs a plurality of brazing materials fixed together.

FIG. 4 is a cross-sectional view of essential parts of a hybrid integrated circuit device that employs only soldering.

[Explanation of symbols]

 20 Insulating Metal Substrate 22 Insulating Resin Layer 24 Die Bond Pad 26 Die Bond Pad 28 Wire Bonding Pad 32 Solder 34 Small Signal Semiconductor Element 36 High Power Semiconductor Element

Claims (2)

[Claims] 1. A hybrid integrated circuit device comprising an insulative substrate, a circuit pattern formed in a predetermined shape on the insulative substrate, and a chip-shaped semiconductor element soldered and fixed onto the circuit pattern. And a tin / lead weight mixture ratio of solder for fixing the semiconductor element is tin / lead = 45/55 to tin / lead = 55/45. 2. A circuit pattern having a predetermined shape is formed on an insulating substrate, and the weight mixing ratio of tin / lead is tin / lead = 45/55 to tin / lead = 55/45 on the fixing pad of the circuit pattern. Manufacturing of a hybrid integrated circuit device characterized by applying the above-mentioned cream solder, mounting a chip-shaped semiconductor element on the fixing pad, and then performing a reflow process in a nitrogen atmosphere to fix the semiconductor element on the fixing pad. Method.