JPH0341473Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a sealing structure for semiconductor elements in semiconductor devices, and in particular to a sealing structure suitable for application to packages such as pin grid arrays. be.

(Prior art) For semiconductor devices equipped with semiconductor elements,
In order to prevent corrosion of the semiconductor element and occurrence of poor electrical connections, it is necessary to seal the semiconductor element as airtight as possible. In other words, it is necessary to prevent the semiconductor element from being directly exposed to moisture in the air.

Conventionally, when packaging a semiconductor element mounted on a substrate in order to seal the semiconductor element, for example, in a chip-on-board type semiconductor device, the following method has been used. That is, as shown in FIG. 6, a semiconductor mounting substrate 50 is formed of an organic material such as glass epoxy resin, a semiconductor element 51 is directly mounted on the semiconductor element mounting portion of this substrate 50, and a wire The substrate 50 is bonded by a method such as bonding.
Make electrical connections with conductor circuits. After that, a liquid or pellet-like sealing resin 52 such as epoxy resin is
was dropped or placed on the semiconductor element 51 after electrical connection was completed, and the sealing resin 52 was melted at a predetermined temperature and then hardened. In addition,
Semiconductor devices formed in this way can be used, for example, as watches,
It is used as an electronic component for cameras, etc.

(Problems to be solved by the invention) However, in the sealing structure of a semiconductor device as shown in FIG. 6, not only is the sealing resin 52 itself inferior in water resistance, but also Since it is not sealed, even if the semiconductor mounting board 5
Even if No. 0 has excellent water resistance, it cannot be said to be a perfect sealing structure.

In response to this, attempts have been made to further secure a cap to the semiconductor mounting substrate 50 to create a reliable sealing structure, but the semiconductor mounting substrate 50 has not been used in areas where high reliability is required. There is an increasing demand for the use of inexpensive organic materials, and the semiconductor mounting substrate 50 made of this organic material must be fixed to the cap using an adhesive made of resin due to adhesive properties. That is,
In the conventional sealing structure, even in the case of a semiconductor device using a cap, a problem arises in that the water resistance of the resin at the joint is poor.

In the conventional sealing structure of a semiconductor device as described above, especially under the recent trend of miniaturization of semiconductor elements mounted on this type of semiconductor device and conductor circuits connected to the semiconductor elements, It was difficult to adequately handle the use in places where high reliability was required, and there were problems in creating a semiconductor device that met the demands of the times.

The purpose of the present invention is to eliminate the above-mentioned problems of the conventional technology, to further improve corrosion of semiconductor elements mounted on a substrate and defective electrical insulation connections, and to mount and seal semiconductor elements. An object of the present invention is to provide a sealing structure in a semiconductor device that has significantly improved reliability against moisture after sealing.

(Means for Solving the Problems) In order to solve the above problems, the means taken by the present invention will be explained with reference to FIGS. 1 to 5 corresponding to the examples. In a semiconductor device 100 in which a semiconductor element 17 mounted on a semiconductor mounting substrate 10 made of metal coating layer 1
4 to form a closed space therein, a cap 30 is formed of metal, and the outer peripheral edge of the cap 30 is coated with a metal coating layer 14.
This is a sealed structure characterized by metal bonding.

Below, the sealing structure according to the present invention will be explained in detail according to a specific example shown in the drawings.

FIG. 1 shows a perspective view of a semiconductor device 100 in which a semiconductor element 17 is sealed by the sealing structure of the present invention, and this semiconductor device 100 mainly includes a substrate 10 for mounting the semiconductor element 17, It consists of a plurality of conductor pins 20 that are forcibly fitted to the substrate 10 and a cap 30 that covers the semiconductor element 17.

The substrate 10 is made of an organic resin material such as glass epoxy resin, glass triazine resin, or glass polyimide resin, and has a recess for mounting a semiconductor element 17 at a predetermined position as shown in FIGS. 2 and 3. A recess 12 is formed, and a conductive circuit 13 is formed around this recess 12. This conductive circuit 13 is formed by a conventional plating method or a method of pasting conductive foil. Further, a plurality of through holes 11 are formed in this substrate 10, and a conductor layer 15 is formed inside these through holes 11. Thereby, each of the through holes 11 becomes a through hole 16. The conductor layer 15 in the through hole 16 and the conductor circuit 13 formed in the recess 12 of the substrate 10 are electrically connected. The semiconductor element 17 mounted in the recess 12 is selectively connected to the conductor circuit 13 by bonding wire or the like, and if necessary, the semiconductor element 17 is surrounded by an organic resin material. It may be implemented by closing the frame 18b and the sealing resin 18a.

Further, as shown in FIGS. 2 and 3, a metal coating layer 14 is formed on the outer peripheral edge of the surface of the substrate 10, and is insulated from the conductor circuit 13 described above. Layer 14 is provided to form a closed space within it, as particularly shown in FIG. That is, when a cap 30 (described later) is metal-bonded to the surface of this metal coating layer 14,
A sealed space is formed between the cap 30 and the substrate 10, and even if the metal coating layer 14 is a conductor, it can maintain an electrically insulated state completely independently of the conductor circuit 13 on the substrate 10. It is something. The material forming this metal coating layer 14 may be the same material as the conductor circuit 13 described above, or may be a completely different material. In this specific example, copper is used. It is made of foil or other metal such as nickel or gold plated on the surface of this copper foil. Furthermore, if the metal coating layer 14 is formed of the same material as the conductor circuit 13, the substrate 10 and the metal coating layer 14 may remain when forming the conductor circuit 13 on the substrate 10. In addition, it can be easily formed by etching a metal layer formed on the substrate 10.

Further, this metal coating layer 14 is used as a cap 3 which will be described later.
Although the main purpose is to perform metal bonding with the substrate 10, as shown in FIG.
If the shape is continuous from the outer peripheral edge of the front surface to the outer peripheral edge of the side surface of the substrate 10 and the lower surface of the substrate 10, moisture can be prevented from entering from the side surfaces and the back surface of the substrate 10, and the present invention The effect of such a sealing structure can be further improved.

The semiconductor device 100 in this specific example has a pin
Since it is a grid array type, conductor pins 20 are fixed to the through holes 16 by forced fitting. Each of these conductor pins 2
0 has a support part 21 formed at its upper end,
Flange portion 2 for ensuring stability with respect to the substrate 10
2 is formed on the top. This conductor pin 20
The support portion 21 has an outer diameter slightly larger than the inner diameter of the through hole 16.
By forcibly fitting the conductor pin 20 into the through hole 16, the conductor pin 20 is fixed to the substrate 10.
Each conductor pin 2 fixed to the board 10 as described above
0 provides electrical continuity from the semiconductor device 100 to a not-shown printed wiring board (motherboard). Note that when fixing the conductor pin 20 to the substrate 10, the conductor pin 20 can be fixed by soldering the fixing portion of the conductor pin 20.
In addition to improving the fixing and holding force of the semiconductor device 100, it is also possible to achieve a remarkable effect in isolating the inside and outside of the semiconductor device 100.

Then, the cap 30 is metal-bonded to the metal coating layer 14 on the substrate 10 formed as described above. This cap 30 is made of metal in order to prevent moisture in the outside air from entering the semiconductor element 17 side, and to quickly dissipate heat generated by the semiconductor element 17 to the outside.
Aluminum, copper, etc. are used as the material. In addition, this cap 30 is designed to prevent the semiconductor element 17 located inside the cap 30 and its bonding wires from coming into direct contact with each other, as shown in FIGS.
As shown in FIG. 5, the central portion thereof has a swollen shape. Further, a bonding portion 31 having a flat surface corresponding to the metal coating layer 14 on the substrate 10 is formed on the outer peripheral edge of the cap 30 in order to make the metal bonding described later more reliable. be. It is convenient to form a solder layer in advance on the bonding surface of the bonding portion 31 in order to facilitate the metal bonding work described below.

Furthermore, if this cap 30 is integrally formed with a fitting part 32 that is continuous with the outer periphery of the joint part 31 and fitted to the outer periphery of the substrate 10, as shown in FIG. The substrate 10 is joined by the joint 32.
The side surface of the cap 30 can be covered, and the positioning of the cap 30 with respect to the substrate 10 can be easily performed.

The metal coating layer 14 and the cap 30 are joined by solder 40, as shown in FIG. That is, the solder 40 is interposed between the joint surfaces of the entire metal coating layer 14 and the joint portion 31 of the cap 30, thereby completing the metal bonding between the metal coating layer 14 and the cap 30. It is. As the material of this solder 40, a tin-lead alloy or the like is used.

(Operation of the invention) In the semiconductor device 100 according to the invention configured as described above, since the metal coating layer 14 formed on the substrate 10 and the cap 30 are metal-bonded, the interior of the cap 30 is The state is completely sealed, making it difficult for moisture in the outside air to reach the semiconductor element 17. Therefore, in this semiconductor device 100, poor electrical connection and corrosion of the semiconductor element 17 due to moisture can be more reliably prevented.

Further, in this semiconductor device 100, the cap 30 is formed of metal and is metal bonded to the metal coating layer 14 on the substrate 10.
It effectively utilizes its property as a good thermal conductor, and transfers the heat radiated from the semiconductor element 17 to the cap 3.
0 and quickly dissipates to the outside.

(Example) Example 1 Electroless copper plating, nickel plating,
After the conductor circuit and the metal coating layer 14 were simultaneously formed using gold plating by a conventional method, the conductor pins 20 were fixed to the substrate 10.

The conductor pin 20 is inserted into the through hole 16 of the substrate 10.
The supporting portion 21 is formed to be wider than the diameter of the hole, and is press-fitted into the through hole 16 of the substrate 10, and the gap is filled with an epoxy sealing resin.

After mounting the semiconductor element 17 on this substrate 10 and electrically connecting the semiconductor element 17 and the conductive circuit 13 by wire bonding, the whole was sealed with an epoxy sealing resin. After the surface of the aluminum cap 30 was replaced with zinc, nickel plating and gold plating were applied. Solder paste is printed on the adhesive surface of the joint portion 31 of this cap 30, this cap 30 is positioned and placed on the board 10, and heat treated in a conveyor type reflow oven at 260°C. and the cap 30 are integrally metal-bonded.

Example 2 Electrolytic copper plating, nickel plating,
After gold plating and simultaneously forming the conductor circuit 13 and the metal coating layer 14 on the substrate 10, the conductor circuit 1
3 and the metal coating layer 14 were cut by counterbore processing.

The conductor pin 20 is inserted into this board 10, and the surface on the conductor pin 20 side is immersed in a solder bath.
was soldered to the substrate 10. Next, the semiconductor element 17 was mounted in the recess 12 of the substrate 10 and wire bonded, and then the entire semiconductor element 17 was sealed with an epoxy resin.

After drawing a copper cap 30 into a convex shape, nickel plating and gold plating were applied, and solder paste was printed on the joint portion 31 of the cap 30. This metal cap 30 was aligned and placed on the substrate 10, and heat treated in an oven at 260° C. for 5 minutes to integrally metal bond the substrate 10 and the cap 30.

(Effects of the Invention) As explained above, according to the semiconductor device 100 according to the present invention, the semiconductor element 17 is exposed to moisture in the outside air.
Since it is possible to almost completely prevent intrusion into the side, the semiconductor element 1 in this semiconductor device 100
7 is improved, and the reliability of the semiconductor device 100 after mounting can be significantly improved.

Furthermore, in the sealing structure of the present invention, the metal coating layer 14 can be formed at the same time as the conductor circuit 13, and the cap 30 can also be easily formed by punching or drawing a metal plate. Because I can,
The semiconductor device 100 according to the present invention can be manufactured extremely easily.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the completed semiconductor device according to the present invention, FIG. 2 is a perspective view of the cap before metal bonding, and FIG. 3 is an enlarged view taken along the - line in FIG. 4 and 5 are sectional views corresponding to FIG. 3 showing another embodiment of the present invention, and FIG. 6 is a sectional view showing a conventional technique. Explanation of symbols, 100...Semiconductor device, 10...
Substrate, 13... conductor circuit, 14... metal coating layer,
17...Semiconductor element, 20...Conductor pin, 30...
... Cap, 31 ... Joint part, 32 ... Fitting part,
40...Solder.

Claims (1)

[Claims for Utility Model Registration] 1. In a semiconductor device in which a semiconductor element mounted on a semiconductor mounting substrate made of an organic material is sealed with a cap, the semiconductor element is attached to the outer peripheral edge of the semiconductor mounting substrate. A metal film layer insulated from the conductor circuit for the cap is provided to form a closed space therein, the cap is formed of metal, and the outer peripheral edge of the cap is metallized to the metal film layer. A sealing structure characterized by: 2. The sealing structure for a semiconductor device according to claim 1, wherein the metal bonding between the metal coating layer and the cap is a soldering bond. 3. The sealing structure for a semiconductor device according to claim 1 or 2, wherein the semiconductor mounting substrate is a pin grid array.