JP2721790B2 - Semiconductor device sealing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to sealing for mounting a semiconductor device on a circuit board, and more particularly to a method for sealing a semiconductor device mounted face down.

[0002]

2. Description of the Related Art Conventionally, soldering has often been used for mounting a semiconductor device on a circuit board. However, in recent years, the spacing between connection terminals has been reduced due to the miniaturization of the package of the semiconductor device and the increase in the number of connection terminals. It has become increasingly difficult to deal with the conventional soldering technology.

Therefore, recently, a method has been devised in which a bare semiconductor device is directly mounted on a circuit board in order to reduce the mounting area and use the device efficiently. As an example, when connecting a semiconductor device to a circuit board, a semiconductor device having an electrode structure composed of a deposited film of an adhesion metal or a diffusion preventing metal on a terminal electrode of the semiconductor device in advance and a solder layer formed by plating on the deposited film. In some cases, the solder is face-down and heated to a high temperature to fuse the solder to the connection electrodes of the circuit board. This mounting structure is considered to be an effective method because the mechanical strength after connection is strong and the connection can be made at once (for example, Industrial Research Council, published on January 15, 1980, edited by Japan Microelectronics Association) , “IC mounting technology”).

[0004] Hereinafter, an example of the above-described conventional semiconductor device sealing method and an example of a mounting body thereof will be described with reference to the drawings.

FIG. 4 is a sectional view of a main part of a conventional semiconductor device mounted face-down.

In FIG. 4, 1 is a semiconductor device, 2 is a terminal electrode of the semiconductor device, 4 is a circuit board, 5 is a connection electrode formed on the surface of the circuit board 4, 8 is the connection electrode 5 and the terminal electrode 2 And 9 is a sealing resin for sealing the semiconductor device 1.

The outline of the conventional method for sealing a semiconductor device mounted face-down and configured as described above, which is configured as described above, will be described below.

First, a semiconductor device 1 having solder bumps
Is mounted face-down after being aligned at a predetermined position of the connection terminal 5 of the circuit board 4, and
The semiconductor device 1 is mounted by heating to a high temperature of ° C. to melt the solder and join it to the connection terminal 5. Then, the semiconductor device 1
A liquid sealing resin is filled in the gap between
By heating and curing at about 0 ° C., a mounted body in which the semiconductor device 1 is sealed with the sealing resin 9 is obtained.

[0009]

However, the above-described semiconductor device package has the following problems.

Since the solder joint 8 has high rigidity and lacks flexibility, when the liquid sealing resin filled in the gap between the semiconductor device 1 and the circuit board 4 is thermoset, the semiconductor device 1 and the circuit board 4 are hardened. The thermal stress generated by the difference in the thermal expansion coefficient of the solder joints 8 is applied to the solder joints 8 to cause a large internal strain.

In order to avoid the influence of the thermal stress as much as possible, a sealing resin which can be cured at a relatively low temperature is used. However, such a sealing resin necessarily has a relatively low glass transition temperature. When the semiconductor device 1 is used at a temperature equal to or higher than the glass transition point of the sealing resin 9, a new thermal stress generated by a large thermal expansion equal to or higher than the glass transition point of the sealing resin 9 is applied to the solder joint 8.

As a result, there is a problem that the connection between the semiconductor device 1 and the circuit board 4 becomes poor in reliability.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a method of sealing a semiconductor device which can connect a semiconductor device and a circuit board with high reliability. It is in.

[0014]

SUMMARY OF THE INVENTION A method for sealing a semiconductor device according to the present invention is a method for sealing a semiconductor device face-down, wherein the semiconductor device is mounted face-down on a circuit board using a conductive adhesive. Filling a gap between the semiconductor device and the circuit board with a thermosetting resin having a glass transition point higher than the operating temperature range of the semiconductor device, and then heat-curing the thermosetting resin at a temperature of 180 ° C. or higher. It is characterized by.

The present invention is suitably applied to a case where a bump electrode of a semiconductor device is mounted on a circuit board using a conductive adhesive. It is also preferable to mix a thermosetting resin with an inorganic feeler to reduce the coefficient of thermal expansion.

[0016]

According to the present invention, by mounting a semiconductor device to be mounted face down on a circuit board using a conductive adhesive, the rigidity of a joint is reduced and flexibility is given. It is possible to reduce the influence of thermal stress caused by the difference in the coefficient of thermal expansion between the semiconductor device and the circuit board when the sealing resin filled in the gap between the board and the substrate is thermally cured. It has become possible. As a result, a resin having a glass transition point higher than the operating temperature range of the semiconductor device can be used as the sealing resin.

By using this resin as a sealing resin for a semiconductor device to be mounted face-down, the resin filled in the gap between the semiconductor device and the circuit board always has a small heat below the glass transition point within the operating temperature range of the semiconductor device. The semiconductor device can have an expansion coefficient, and a highly reliable semiconductor device package can be obtained.

[0018]

An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1 to 3 illustrate a method of sealing a semiconductor device according to an embodiment of the present invention.

1 to 3, reference numeral 1 denotes a semiconductor device, 2 denotes a terminal electrode, 3 denotes a conductive adhesive used for mounting the semiconductor device 1, 4 denotes a circuit board, and 5 denotes a surface of the circuit board 4. The connection electrode 6 is a thermosetting resin.

A method for sealing a semiconductor device having the above-described structure and a package thereof will be described below with reference to the drawings.

First, the conductive adhesive 3 is formed on the terminal electrode 2 of the semiconductor device 1 in advance. At this time, the conductive adhesive 3 may be formed directly on the terminal electrode 2 or may be formed on a bump electrode (bump) formed on the terminal electrode 2 in advance.

Then, as shown in FIG. 1, the semiconductor device 1 is face-down (downward), positioned with respect to the connection electrodes 5 of the circuit board 4, and after mounting the semiconductor device 1 on the circuit board 4, heating is performed. Then, the conductive adhesive 3 is cured to electrically connect the terminal electrodes 2 of the semiconductor device 1 and the connection electrodes 5 of the circuit board 4 as shown in FIG.

Next, as shown in FIG.
After filling the gap between the resin and the circuit board 4 with a thermosetting resin 6 (for example, epoxy resin), the thermosetting resin 6 is cured by heating at a temperature of 180 ° C. or higher.

In the heat curing of the thermosetting resin 6, the thermosetting resin 6 cures and contracts as the curing reaction of the thermosetting resin 6 progresses, and the contraction force causes the semiconductor device 1 and the circuit board 4 to shrink. The bonding strength of the bonding portion in the conductive adhesive 3 is increased, and the bonding stability is improved.

As the thermosetting resin 6 used at this time, a thermosetting resin whose glass transition temperature is higher than the operating temperature range of the semiconductor device is used.

According to the above-described method, in the semiconductor device 1 having completed the sealing process, as shown in FIG. 3, the semiconductor device 1 in which the gap between the semiconductor device 1 and the circuit board 4 is filled with the resin 6 after thermosetting. To get the implementation.

In this package, since the resin 6 after the thermosetting in the gap between the semiconductor device 1 and the circuit board 4 has a glass transition point higher than the operating temperature range of the semiconductor device 1,
The semiconductor device 1 always has a small coefficient of thermal expansion when it is used, so that the bonding between the semiconductor device 1 and the circuit board 4 can always be maintained in a stable state, and a highly reliable package of the semiconductor device. Can be realized.

In the method of sealing a semiconductor device according to the present invention, a thermosetting resin having a glass transition point higher than the operating temperature range of the semiconductor device can be used. The subsequent thermal expansion of the resin can be maintained at a small thermal expansion coefficient equal to or lower than the glass transition point, and the bonding stability can be maintained.

Further, according to the present invention, a thermosetting resin having a glass transition point higher than the operating temperature range of the semiconductor device can be used, which is a problem in the conventional semiconductor device mounted face down. The thermal stress on the joint due to the thermal expansion of the sealing resin in the gap between the semiconductor device and the circuit board becomes extremely small, and a highly stable and highly reliable semiconductor device package can be obtained.

Although the conductive adhesive 3 is formed on the terminal electrode 2 of the semiconductor device 1 in the embodiment, it may be formed on the connection electrode 5 of the circuit board 4.

The material of the conductive adhesive 3 is epoxy resin, silicone resin, polyimide resin, phenol resin or the like containing conductive powder such as Ag, Au, Ni, Cu, etc., and has good conductivity. Any conductive adhesive may be used.

Similarly, the material of the thermosetting resin 6 may be any resin such as an epoxy resin, a silicone resin, a polyimide resin, and a phenol resin as long as the resin has a glass transition point higher than the operating temperature range of the semiconductor device 1. It may be something.

Further, when the thermosetting resin 6 is mixed with an inorganic filler such as silica to reduce the thermal expansion coefficient, the effect can be further exhibited.

[0035]

As described above, according to the method of sealing a semiconductor device of the present invention, the semiconductor device is bonded to the circuit board using a flexible conductive adhesive. The effect of thermal stress caused by the difference in thermal expansion coefficient can be reduced, and the sealing resin can be cured by heating at a temperature of 180 ° C. or higher. For this reason, a thermosetting resin having a glass transition point equal to or higher than the operating temperature range of the semiconductor device can be used as the sealing resin, and the semiconductor device and the circuit board are bonded face down using a conductive adhesive. In the device, the thermal expansion of the resin after thermal curing of the gap between the semiconductor device and the circuit board can be maintained at a small thermal expansion coefficient equal to or lower than the glass transition temperature, and the conductive adhesive at the junction between the semiconductor device and the circuit board Can maintain the stability of bonding.

Further, the semiconductor device package encapsulated by the method of the present invention uses a thermosetting resin having a glass transition point higher than the operating temperature range of the semiconductor device. In this case, the thermal stress on the joint due to the thermal expansion of the sealing resin in the gap between the semiconductor device and the circuit board becomes extremely small, and a highly stable and highly reliable semiconductor device package can be obtained.

[Brief description of the drawings]

FIG. 1 is a process diagram illustrating a method for sealing a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a process diagram illustrating a method for sealing a semiconductor device according to an embodiment of the present invention.

FIG. 3 is a sectional view of a main part of a semiconductor device package according to one embodiment of the present invention;

FIG. 4 is a cross-sectional view of a main part of a conventional semiconductor device mounted face-down.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor device 2 Terminal electrode 3 Conductive adhesive 4 Circuit board 5 Connection electrode 6 Thermosetting resin

Claims (3)

(57) [Claims] 1. A method of sealing a semiconductor device, wherein the semiconductor device is mounted face down on a circuit board by using a conductive adhesive, the temperature of the semiconductor device being set in a gap between the semiconductor device mounted face down and the circuit board. after filling the thermosetting resin having a glass transition temperature of more than the range, the sealing method of a semiconductor device characterized by causing heat curing the heat-curable resin at 180 ° C. or higher. 2. The method according to claim 1, wherein the protruding electrodes of the semiconductor device are mounted on a circuit board using a conductive adhesive. 3. The method according to claim 1, wherein an inorganic filler is mixed with the thermosetting resin to reduce the coefficient of thermal expansion.