JP2000311916A - Hybrid integrated circuit device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To connect a wiring board and an insulative case housing it with high connection reliability, without breaking wires even under an environment with an operating atmosphere tending to a high temp. with rapid changes in the temp. SOLUTION: This device comprises a wiring board 2, having connection electrodes 7 provided on the surface of an insulation board 4, an insulative case 3 which is made of an insulation material having a thermal expansion coefficient higher than that of the board 4, houses the wiring board 2 inside, and has connection electrodes 9 provided at positions facing the electrodes 7 of the wiring board 2, and a cover 15 for sealing the wiring board 2 in the insulative case 3, and the connection electrodes 7, 9 are electrically connected through looped wires 10 of 500 μm or smaller diameter, so that the valve represented by (θ/h)/h is 6 or less where the max. rise angle is θ( deg.) and the max. loop height of the wire 10 from the connection electrodes 7, 9 is h(mm).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic package such as a semiconductor integrated circuit board in which various electronic components such as a capacitor and a resistor are mounted in addition to a semiconductor element. The present invention relates to a hybrid integrated circuit device in which a wiring board is sealed in a container formed of an insulating case and a lid, and is particularly suitable for use in a vehicle such as an automobile. The present invention relates to an improvement for improving the connection reliability of a bonding case with a bonding case.

[0002]

2. Description of the Related Art Conventionally, a hybrid integrated circuit device is constructed by appropriately enclosing a wiring board composed of a package for accommodating a semiconductor element and a hybrid integrated circuit board on which a plurality of various electronic components are mounted in a predetermined container. I have.

As shown in FIG. 4, for example, as shown in FIG. 4, in order to radiate heat generated from various electronic parts 21 such as a semiconductor element 20 and a resistance element to the outside, a semiconductor element 20 and an electronic part A heat sink 23 is attached to the back surface of the wiring board 22 on which the circuit board 21 is mounted. Then, the wiring board 22 to which the heat sink 23 is attached is
It is stored in the insulating case 24.

A connection electrode 25 for connecting to an external circuit is formed on the surface of the wiring board 22.
In order to electrically connect with the connection electrode 25 of the wiring board 22, the insulating case 24 has a connection electrode 25 of the wiring board 22.
A case-side connection electrode 26 is formed at a position opposite to. The connection electrode 25 and the case-side connection electrode 2
6 means that the wire diameter of a metal such as aluminum is about 100 μm to 500 μm by a wire bonding method or the like.
are electrically connected by a large diameter wire 27 of m. The wiring board 22 and the wire 2
7 is buried by a protective gel material 28,
The integrated circuit device is obtained by joining and sealing the lid 29 to the opening of the case 24.

[0005]

However, in the above-described conventional hybrid integrated circuit device, the case 24 is caused by a sudden change in the ambient temperature during operation or a temperature change due to heat generation of the semiconductor element 20 or the electronic component 21. There has been a problem that thermal deformation occurs and the wire 27 that connects the connection electrode 26 of the case 24 and the connection electrode 25 of the wiring board 22 is broken.

For example, when the insulating substrate of the wiring substrate constituting the hybrid integrated circuit device is made of alumina (Al ₂ O ₃ ) ceramics, the coefficient of thermal expansion is about 7 × 10 ⁻⁶ / ° C., and is represented as a case material. The thermal expansion coefficient of PBT resin is 50 × 10 ^-6
/ ° C., since the expansion and contraction of the case 24 is much larger than that of the wiring board 22 due to the above-mentioned temperature change, a large distortion occurs at the connection point of the wire 27 with the case-side connection electrode 26. If the environment is maintained such that a temperature change is repeatedly generated, the distortion is repeatedly generated, and eventually the wire 27 is disconnected near the connection point with the case-side connection electrode 26.

For this reason, in the connection structure using the wires 27, the operating atmosphere tends to be high in temperature, and it is very difficult to secure high connection reliability as a hybrid integrated circuit device for a vehicle such as an automobile whose temperature changes rapidly. Met.

In order to solve such a problem, a case for accommodating a wiring board is provided with a reinforcing fiber oriented in a predetermined direction and a baffle for changing the orientation direction of the reinforcing fiber. Japanese Patent Application Laid-Open No. Hei.
However, such measures by changing the structure or material of the case cause an increase in the number of parts, an increase in the cost of parts, and an increase in man-hours, and often cause a problem in mass productivity. Simpler measures have been needed.

[0009] As a method for ensuring the durable connection reliability of the bonding wire without changing the structure, a method of increasing the loop height h of the wire is known. However, there are problems such as the miniaturization of the device progressing, the height of the accommodation space is restricted, and a large amount of the protective gel material 28 for protecting the wires is required. It has been very difficult to ensure connection reliability with high durability by a connection method using a wire having a diameter.

Accordingly, an object of the present invention is to provide a high operating atmosphere without a break in a wire connecting a connection electrode of a case and a connection electrode of a wiring board even in an environment where the temperature is easily changed and the temperature is drastically changed. An object of the present invention is to provide a hybrid integrated circuit device having connection reliability.

[0011]

The inventor of the present invention has studied the connection structure using wires in order to solve the above-mentioned problems. As a result, the connection reliability of the wires is not limited to the loop height h, but also to the case side connection. The inventors have focused on the fact that they greatly depend on the rising angle θ of the wire in the electrode, and found that the breaking life of the wire becomes longer as (θ / h) / h becomes smaller, leading to the present invention.

That is, a hybrid integrated circuit device according to the present invention comprises: a wiring board having a first connection electrode provided on a surface of an insulating substrate;
An insulating material which is made of an insulating material having a larger thermal expansion coefficient than the insulating substrate, houses the wiring substrate therein, and has a second connection electrode provided at a position facing the first connection electrode of the wiring substrate. And a lid for sealing the wiring board in the insulating case, wherein the first connection electrode and the second connection electrode have a loop-shaped wire diameter of 500 μm or less. In a hybrid integrated circuit device electrically connected by wires, the maximum rise angle of the wire from the connection electrode is θ (°), and the maximum loop height of the wire from the connection electrode surface is h (mm). When
The value represented by (θ / h) / h is 6 or less, and particularly, the wire diameter of the wire is 100 μm.
m, the wire is made of a metal containing aluminum as a main component, the first connection electrode surface and the second connection electrode surface are substantially the same height, The insulating substrate in is made of ceramics,
The insulating case is further characterized by being made of an insulating material containing an organic resin, and the hybrid integrated circuit device is suitably used for a vehicle.

[0013]

In the connection structure of the wiring between the connection electrode on the wiring board and the connection electrode in the case for housing the wiring board, the disconnection of the wire near the connection point with the connection electrode causes the connection between the insulating substrate of the wiring board and the case. Due to the thermal expansion difference, the distance between the connection electrodes changes repeatedly,
This is because plastic strain accumulates near the connection point between the wire and the electrode, and the wire undergoes fatigue failure.

The plastic strain in the vicinity of the connection point of the wire with the connection electrode tends to decrease as the height h of the loop increases and as the maximum rise angle θ of the wire at the connection electrode decreases. Specifically, the plastic strain decreases in proportion to (θ / h) / h. From this principle, (θ / h) /
By reducing the value of h, in other words, by reducing the maximum rising angle θ of the wire with respect to the maximum loop height h of the wire, the long-term connection reliability of the wire can be reduced without increasing the loop height of the wire. Performance can be improved. Further, according to this structure, there is no need to change the structure of the wiring board, the case, and the like, so that there is no problem in productivity.

Further, such a structure has a wire diameter of 50 mm.
When it is larger than 0 μm, the wire diameter is required to be 500 μm in order to increase the rigidity of the wire and to make it difficult for the wire to absorb the displacement difference between the connection electrodes and to easily break the wire. In addition, by configuring the wire with a metal containing aluminum as a main component, the bonding operation can be facilitated and the product cost can be reduced.

Further, the first connection electrode surface and the second connection electrode surface
It is desirable that the connection electrode surface has substantially the same height as the connection electrode surface in order to increase the productivity by the wire bonding method.

Further, the above configuration is most effective when the insulating substrate in the wiring substrate is made of ceramics and the insulating case is made of an insulating material containing an organic resin.

According to this configuration, excellent connection reliability can be exhibited even under severe conditions exposed to high-temperature and low-temperature atmospheres, and is particularly responsible for engine control, transmission control, chassis control, etc. of an automobile or the like. It is most suitably used for hybrid integrated circuit devices for vehicles.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a hybrid integrated circuit device according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic sectional view of a hybrid integrated circuit device according to the present invention. In FIG. 1, 1
Denotes a hybrid integrated circuit device, 2 denotes a wiring board, and 3 denotes an insulating case. According to the wiring board 2, the wiring circuit 11 is formed on the surface of the insulating substrate 4 and electrically connected to the electronic components 6 such as the semiconductor element 5 and the resistance element mounted on the surface of the insulating substrate 4. Thus, an electric circuit is formed. A connection electrode 7 for connecting to an external circuit is formed on an end of the wiring board 2.

A heat sink 8 made of highly thermally conductive ceramic is joined to the back surface of the wiring board 2 to dissipate the heat generated from the semiconductor elements 5 and the electronic components 6 mounted on the front surface.

The wiring board 2 is made of an insulating case 3
Inside, the heat sink joined to the wiring board 2 is stored and fixed so as to be exposed from the lower surface of the case 3.
Also, the connection electrodes 7 on the wiring board 2 of the insulating case 3
A connection electrode 9 is formed on the surface of the case 3 facing the substrate 3, and the connection electrode 9 is electrically connected to a connection terminal (not shown) provided on the case 3.

The connection electrode 7 on the wiring board 2 and the connection electrode 9 on the case 3 have a wire diameter of 100 to 500 μm.
Are electrically connected by wires 10. The connection by the wire 10 is performed by a general wire bonding apparatus.

According to this wire bonding apparatus,
As shown in FIG. 3A, first, the wire 10 held by the clamp 13 is connected to the connection electrode 9 by the ultrasonic bonding tool 12. Next, as shown in FIG. 3B, the tool 12 is moved, the wire 10 is bonded and connected to the connection electrode 7, and the end of the wire 10 is cut off as shown in FIG. 3C. Connection electrodes 7, 9
Can be connected by a loop-shaped wire 10. The order of connection by the ultrasonic bonding tool 12 may be from the connection electrode 7 to the connection electrode 9.

According to the present invention, in the above loop shape, as shown in FIG. 2, the larger one of the rising angles θ ₁ and θ ₂ of the wire 10 inside the loop shape of the connection electrodes 7 and 9 ( In FIG. 2, θ ₁ ) is the maximum rising angle θ (°), and the larger one of the heights from the loop-shaped connection electrodes 7 and 9 to the top of the loop is defined as the maximum loop height h (mm). )), It is important that the value represented by (θ / h) / h is 6 or less, particularly 5 or less, and more preferably 4 or less.

This is important for improving the connection reliability between the connection electrodes 7 and 9. If the above value is larger than 6,
A large plastic strain is generated in the connection portion having a large rising angle, and a disconnection is likely to occur on the connection electrode side of the wire 10 having a large rising angle, so that connection reliability cannot be secured.

It is also important that the wire diameter of the wire 10 is 500 μm or less, particularly 400 μm or less. This is because if the wire diameter of the wire is larger than 500 μm, the rigidity of the wire 10 itself becomes high, and the wire 10 itself cannot absorb the displacement difference between the connection electrodes 7 and 9, causing disconnection. Note that the wire diameter of the wire 10 is desirably 100 μm or more. This means that the wire diameter of the wire 10 is 1
If the thickness is smaller than 00 μm, the wires cannot accept a current of 0.1 A or more generally applied to a hybrid integrated circuit, and it is necessary to connect the connection electrodes 7 and 9 with two or more wires. This results in an increase in man-hours and costs.

The maximum loop height h of the wire 10
If the ratio is too low, it is difficult to form a loop shape in a device, and at the same time, the displacement difference between the connection electrodes 7 and 9 cannot be sufficiently absorbed, and there is a possibility of disconnection. On the other hand, if the maximum loop height is too high,
Since the external shape of the hybrid integrated circuit device becomes large, the required amount of the protective gel used for preventing corrosion of the wire increases, and the cost increases, the height is 10 m.
m or less is appropriate.

Although the maximum loop height position is not particularly limited, as shown in FIG. 2, a wire is connected from the connection electrode 9 of the case 3 to the connection electrode 7 of the wiring board 2 by an ultrasonic bonding tool. In the case of connection, the maximum loop height position is higher than the middle position of the connection electrodes 7 and 9 in case 3.
To the connection electrode 9 side. Conversely, when a wire is connected from the connection electrode 7 on the wiring board 2 side to the connection electrode 9 on the case 3, the maximum loop height position is closer to the connection electrode 7 side of the wiring board 2 than the intermediate position between the connection electrodes 7 and 9. Shift to

The maximum rising angle θ of the wire 10 is preferably as small as possible in order to make (θ / h) / h 6 or less without increasing the loop height h. In some cases, the rigidity of the wire is increased, so that the displacement difference between the connection electrodes cannot be absorbed, and peeling failure may occur at the bonding wire connection portion. Therefore, the maximum rising angle θ is desirably 30 ° or more. On the other hand, if the maximum rising angle θ is too large, large plastic deformation occurs at the rising portion of the bonding wire, and long-term reliability cannot be ensured due to this plastic strain, and disconnection may occur. Therefore, the maximum rising angle θ is desirably 120 ° or less, and particularly desirably 100 ° or less.

If the distance between the connection electrodes 7 and 9 is short, there is a possibility that the interference of the bonding tool may occur.
As the distance between the connection electrodes 7 and 9 increases, the outer shape of the hybrid integrated circuit device also increases. Therefore, the distance between the connection electrodes 7 and 9 is suitably 3 to 20 mm.

It is desirable that the heights of both electrode surfaces of the connection electrodes 7 and 9 are substantially the same, in other words, in the same plane, from the viewpoint of wire connectivity by a wire bonding apparatus.

The insulating substrate 4 constituting the wiring substrate in the hybrid integrated circuit device of the present invention is desirably made of ceramics in order to enhance excellent durability and reliability even in a severe environment. Is alumina (Al
_At least one selected from the group consisting of ₂ O ₃ ) ceramics, aluminum nitride (AlN) ceramics, silicon nitride (Si ₃ N ₄ ) ceramics, mullite (3Al ₂ O ₃ .2SiO ₂ ) ceramics, and glass ceramics Are preferably used.

The wiring circuit 11 and the connection electrodes 7 constituting the wiring board 2 are made of a metal such as W, Mo, Mo-Mn, Cu, or Al.
Plating or Au plating may be applied. In particular, in terms of the connectivity with the surface of the connection electrode 7 and the bonding wire, Ni
It is desirable that plating be performed and further that Au plating be performed.

The heat sink 8 joined to the wiring board 2 is aluminum (Al) having a coefficient of thermal expansion of 23 × 10 ⁻⁶ / ° C. and copper (Cu) having a coefficient of thermal expansion of 17 × 10 ⁻⁶ / ° C.
And ceramics such as aluminum nitride (AlN) having a coefficient of thermal expansion of 5 × 10 ⁻⁶ / ° C. and silicon carbide (SiC) also having a coefficient of thermal expansion of 4 × 10 ⁻⁶ / ° C. Is bonded to the wiring board 2 with, for example, a silicone-based adhesive or the like.

The insulating case 3 contains an organic resin in order to protect the wiring board 2, secure airtightness, and insulate and protect connection electrodes for making an electrical connection to an external circuit. It is desirable to be made of an insulating material.

As the organic resin contained, a known PP
S resin, PBT resin, etc. are mentioned. In addition, in order to improve characteristics, such as mechanical strength, this insulating material is 20-.
About 40% by weight of glass fiber, inorganic fiber such as carbon fiber, glass, SiO ₂ , Al ₂ O ₃ , Al
A composite material obtained by adding and mixing an inorganic powder such as N, Si ₃ N ₄ or mullite may be used.

It is desirable that the connection electrode 9 formed on the surface of the case 3 be made of copper or a known alloy containing copper as a main component. For the same reason as in No. 7, it is desirable that Ni plating and Au plating are sequentially applied.

On the other hand, the wire constituting the wire 10 is at least one selected from the group consisting of Al, Au and Cu.
Although a metal containing a seed as a main component is preferably used because of its low resistance, in the case of a metal containing Au as a main component, it is necessary to heat a connection electrode to a predetermined temperature during bonding, and Since the wire diameter is large and the loop length is long, it is difficult in terms of equipment and cost, so it is best to use a metal mainly composed of aluminum or copper, especially a metal mainly composed of aluminum. desirable. The wire 10 may be plated with Ni or Au on the surface of the wire.

As another form, for example, when connecting with an aluminum wire, the surfaces of the connection electrodes 7 and 9 are
By attaching a plate (post) made of 42 alloy or aluminum with solder or the like and connecting a wire to the post, the reliability of connection of the wire to the connection electrode can be increased.

The connection electrodes 7 and 9 are connected by wires 10.
In the case where the connection is made, it is desirable that the connection points of the wires 10 have substantially the same height. This is because if the height of the connection point is different, the tool of the wire bonding apparatus will interfere with the insulating case or the wiring board, making the bonding work difficult or causing the wire to come into contact with the stepped portion and cause the wire to break. It may be. In addition, the difference in height at the connection point is ± 0.5 mm with substantially the same height.
It is good if it is within.

As described above, the wiring board 2 connected to the insulating case 3 and the connection electrodes 7 and 9 by the wires 10 is connected to the insulating gel 14 such as a silicone-based gel in the case 3 together with the connection portion by the wires 10. By filling a cover 15 made of a known metal such as PPS resin, PBT resin, or aluminum alloy into the opening of the case 3, the inside of the container formed of the case 3 and the cover 15 is filled. The wiring board 2 is housed in the hybrid integrated circuit device.

[0042]

Next, the hybrid integrated circuit device of the present invention was evaluated as described in detail below. First, in preparing an insulating substrate for a wiring board, a known organic binder and a plasticizer were added to a raw material powder in which SiO ₂ , MgO, and CaO were added in a total ratio of 8% by weight to Al ₂ O ₃ as an auxiliary agent. After adding an appropriate amount of a solvent and mixing to prepare a slurry, the slurry was formed into a ceramic green sheet having a thickness of about 300 μm by a well-known tape forming technique such as a doctor blade method or a calendar roll method.

Next, a through hole was formed at a predetermined position of the ceramic green sheet by punching. Then, a metal paste prepared by adding an appropriate amount of alumina powder to a powder mainly composed of a high melting point metal such as W or Mo and adding and mixing a known organic binder, a plasticizer, and a solvent to the ceramic green sheet is desired. And the metal paste was also filled into the through-hole portions by the screen printing or pressure filling method.

Next, the green sheets are laminated and fired at a temperature of about 1600 ° C. in a reducing atmosphere comprising a mixed gas of hydrogen (H ₂ ) and nitrogen (N ₂ ). Ni plating and Au plating are applied to the surface of the wiring circuit and the connection electrode formed at a thickness of 5 μm and 0.5 μm, respectively, by an electroless plating method, and then a copper paste is applied thereon by printing and coating at a temperature of about 1000 ° C. By baking, a wiring board having a thickness of about 1.25 mm was produced.

On the other hand, an aluminum alloy for die casting was used as a heat sink, and was formed into a predetermined shape by die casting.

On the other hand, as an insulating case, a connection electrode made of a Cu plate was inserted into a mold and injection-molded using a PBT resin mixed with 30% by weight of glass fiber.

After the wiring substrate thus obtained is aligned and fixed to the heat sink with a thermosetting silicone-based adhesive on the back surface of the wiring substrate, the wiring substrate is further fixed to the insulating case by the thermosetting silicone. It was fixed with a system adhesive.

Thereafter, the connection electrode of the wiring board and the connection electrode of the resin case are connected by a wire bonding method to a wire diameter of 30 mm.
The connection was made with a 0 μm aluminum wire.

At this time, the movement of the bonding tool at the time of wire bonding is changed, or the wire loop is forcibly adjusted by pressing or pulling the wire loop from above after connection to form loops having different shapes as shown in Table 1. did. Then, after filling the silicone gel in the resin case, a lid made of an aluminum alloy manufactured by sheet metal processing was attached to the opening of the case with an adhesive to obtain a hybrid integrated circuit device for evaluation.

Using the thus-obtained hybrid integrated circuit device for evaluation, a liquid tank cooling / heating cycle test in a temperature range of −50 ° C. to 150 ° C. was performed, and the electric resistance between the wiring board and the electrode of the case was determined every 100 cycles. Was measured, and the number of cycles when the resistance increased with respect to the initial resistance was shown in Table 1.

[0051]

[Table 1]

As a result, the sample No. 1 of the comparative example outside the present invention was obtained.
Nos. 4 to 4 are cases in which the loop height was reduced while keeping the conventional shape, and the wire was disconnected on the connection electrode side of the case in 800 cycles or less, resulting in poor conduction. Further, in Sample No. 14 having a wire diameter larger than 500 μm, the durability was extremely reduced.

On the other hand, in the present invention, the loop was formed such that the maximum rising angle θ of the wire was reduced and (θ / h) / h was 6 or less even with the same loop height as the comparative example. Thereby, it was confirmed that connection reliability of 1000 cycles or more can be secured. Further, even when (θ / h) / h is 6 or less, if the maximum loop height is 2 mm or more and θ is in the range of 30 ° to 120 ° and the value is 5 or less, 150
From 0 cycles to 4 cycles, high reliability of 2500 cycles or more was confirmed.

[0054]

As described above, according to the hybrid integrated circuit device of the present invention, in the structure in which the connection electrodes formed on the wiring board and the insulating case accommodating the wiring board are connected by the wire bonding method, By controlling the shape to satisfy the specific conditions, the operating atmosphere tends to be high temperature, and even under the use environment conditions where the temperature changes sharply, the generation of distortion near the connection point with the connection electrode of the wire is suppressed,
Even if the wire is operated for a long time under the severe atmosphere, the wire itself is not broken, and high connection reliability is obtained, whereby the reliability as a hybrid integrated circuit device for a vehicle such as an automobile can be improved at the same time. .

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing one embodiment of a hybrid integrated circuit device of the present invention.

FIG. 2 is an enlarged cross-sectional view of a connection portion by a wire in the hybrid integrated circuit device of FIG.

FIG. 3 is a diagram for explaining a connection method using wires between connection electrodes.

FIG. 4 is a schematic sectional view showing a conventional hybrid integrated circuit device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hybrid integrated circuit device 2 Wiring board 3 Insulating case 4 Insulating substrate 5 Semiconductor element 6 Electronic component 7, 9 Connection electrode 8 Heat sink 10 Wire 11 Wiring circuit

Claims (6)

[Claims] 1. A wiring board having a first connection electrode provided on a surface of an insulating substrate, and an insulating material having a thermal expansion coefficient larger than that of the insulating substrate. An insulating case in which a second connection electrode is provided at a position facing the first connection electrode of the substrate, and a lid for sealing the wiring board in the insulating case; In a hybrid integrated circuit device in which a first connection electrode and the second connection electrode are electrically connected by a loop-shaped wire having a wire diameter of 500 μm or less, the maximum rising angle of the wire from the connection electrode is θ. (°), the maximum loop height of the wire from the connection electrode surface is h (m)
m), the value represented by (θ / h) / h is 6 or less. 2. The hybrid integrated circuit device according to claim 1, wherein said wire has a wire diameter of 100 μm or more. 3. The wire according to claim 1, wherein the wire is made of a metal containing aluminum as a main component.
A hybrid integrated circuit device as described. 4. The hybrid integrated circuit according to claim 1, wherein said first connection electrode surface and said second connection electrode surface have substantially the same height. apparatus. 5. The hybrid according to claim 1, wherein the insulating substrate of the wiring substrate is made of ceramics, and the insulating case is made of an insulating material containing an organic resin. Integrated circuit device. 6. The hybrid integrated circuit device according to claim 1, which is used for a vehicle.