JPH03283548A - Sealed type semiconductor device - Google Patents

Abstract

PURPOSE:To enable short-time and easy operation of a device excellent in hermetic sealing and in post-mounting moisture-resistant reliability with no cracks developed in resin by such a layout that a semiconductor chip is surrounded by a package material whose metal layer is both-coated with resin layers and by sealing it by thermocompression bonding. CONSTITUTION:A semiconductor chip 19 whose top electrodes are bonded with leads 22 by wires 21 is sealed in such a way as to be sandwiched by a box-type package material 14 with resin layers 12, 13 deposited on both faces of a metal layer 15 and by a flat-type package material 18 with a similar metal layer 15 coated with similar resin layers 16, 17. The upper box-type package material 14 has a flange 14a at the open end rim and is bonded with leads 22 at this flange 14a with the resin of a resin layer. The device is manufactured by thermocompression bonding of the peripheries of both package materials 14, 18. This constitution allows metal layers to inhibit infiltration of water into the package.

Description

[Detailed Description of the Invention] [Object of the Invention] (Field of Industrial Application) The present invention relates to a sealed semiconductor device, and more specifically, to sealing of large elements, sealing of ultra-thin packages, and surface mounting. This invention relates to improvements in semiconductor element sealing such as package sealing.

(Conventional technology) Conventional encapsulation of semiconductor devices mainly uses metals, ceramics,
Packages can be broadly classified into packages that are sealed using glass or the like, and plastic packages that are sealed with epoxy resin or the like using a transfer molding device.

Hollow packages that are sealed using metal, ceramic, glass, etc. have high airtightness and excellent reliability, but they have disadvantages such as poor productivity, high price, and high hardness and poor toughness. There is. For bonding during sealing, a low melting point glass method or a metallization/metal solder method is used.

In addition, as an alternative adhesion method, low temperature (100 to 2
Methods using organic adhesives that can be bonded at temperatures (00°C) have been used, but there are problems such as poor reliability, limited organic materials, poor heat resistance, and poor productivity. Ta.

For these reasons, plastic packages are currently the mainstream for encapsulating semiconductor devices.

Note that as the resin sealing method, a potting method using liquid resin has also been put into practical use.

Incidentally, in recent years, in the field of resin encapsulation of semiconductor devices, with the increase in the degree of integration of semiconductor elements, various functional units on the elements have been miniaturized and the size of the elements themselves has rapidly progressed. In addition, ASIC (AppHcat1onSpe
Surface-mount packages, such as gate arrays (eif1e ICs) and standard cell type LSIs, are rapidly progressing. When mounting these surface mount packages, processes such as vapor phase reflow, infrared reflow, and solder immersion are employed. These steps expose the package to high temperatures (215-260°C).

Therefore, in a resin-sealed semiconductor device sealed with an epoxy resin, a small amount of moisture that penetrates the resin and enters the inside rapidly evaporates, causing cracks in the sealing resin layer. If this crack reaches the outside, a serious problem arises in that moisture resistance reliability cannot be guaranteed. Furthermore, a phenomenon occurs in which the resin bulges and cannot be mounted. Furthermore, PSG (phosphosilicate glass) and 5iN (silicon nitride) are used as passivation films for wiring layers such as aluminum.
Problems such as cracks occurring in the film, peeling of the passivation polyimide film, and disconnection of the Au bonding wire occur frequently.

These measures include (1) reducing the stress on the internal encapsulation of the sealing resin, and reducing the PSG% on the sealing resin and the element;
Encapsulation resins for large packages are required to improve adhesion with SiN, polyimide films, and lead frames, (2) provide high-temperature strength and moisture absorption high-temperature strength corresponding to the mounting temperature, and reduce moisture absorption. It is increasing mainly in

From these viewpoints, the practical use of sealing resins such as maleimide resins, PPS (polyphenylene sulfide) resins, PPO (polyhydroxyphenylene ether) resins, and liquid crystal polymers is being considered. Furthermore, recently, a resin that is a combination of a maleimide resin and an epoxy resin, or an aminobismaleimide resin that is a combination of a bismaleimide resin and 4,4-diaminodiphenylmethane has been proposed as a sealing resin.

On the other hand, resin-sealed semiconductor devices (for example, Japanese Patent Laid-Open No. 60-20884
Publication No. 7) has been proposed. In this semiconductor device, a cylindrical or polygonal hole is provided in the mold resin (sealing resin) below the die pad to form an extremely thin part or a part without mold resin. The structure is such that the gas generated by the evaporation of moisture inside the mold resin escapes from the extremely thin portions mentioned above. In addition, a method of forming a metallic coating layer on the package surface using a transfer molding method has also been proposed. However, none of the resin-sealed semiconductor devices was fully satisfactory in terms of productivity and moisture resistance reliability.

Furthermore, hollow plastic packages have been proposed in order to alleviate the above-mentioned problems during mounting and to prevent aluminum wiring from shifting or breaking due to the influence of the sealing resin, but they have problems with manufacturability and moisture resistance. It was not sufficient from that point of view.

(Problems to be Solved by the Invention) The present invention has been made to solve the above-mentioned problems. An object of the present invention is to provide a sealed semiconductor device that can be mounted without various problems.

[Structure of the Invention] (Means for Solving the Three Problems) In order to solve the above problems, the present invention arranges a package material in which both sides of a metal layer are covered with a resin layer to surround a semiconductor element. , we present a sealed semiconductor device i=3, which is characterized by being sealed by heat-pressing.

There is no particular restriction on the resin that is coated on both sides of the metal layer constituting the package material used in the present invention, and thermoplastic resins or B-staged thermosetting resins are used. However, those with excellent heat resistance, moisture resistance, insulating properties, and adhesive properties are preferred, and among these, from the viewpoint of reliability, high purity materials that have as few ionic impurities as possible and do not contain low molecular weight components are particularly preferred. Examples of thermoplastic resins include polysulfone, polyether sulfone, polyphenylene sulfide (PPS) resin, polyhydroxyphenylene ether (PPO) resin, polyethylene terephthalate resin, polybutylene terephthalate resin, and These liquid crystal polymers, polyether ether keto:/(PEEK) based resins, polyketone sulfide (PKS) based resins, fluororesins (PFA)
) and other engineering plastic resins.

Examples of B-staged thermosetting resins include epoxy resins, phenol resins, maleimide resins, silicone resins, urethane resins, diallyl phthalate resins, and unsaturated polyester resins.

The thickness of each resin layer can be appropriately selected in consideration of ensuring adhesion by thermocompression bonding and insulation with respect to the metal layer. It is sufficient that each resin layer has a thickness of 5 μm or more.

Examples of the metal forming the metal layer include iron, nickel, copper, gold, silver, aluminum, tin, stainless steel, lead, and alloys thereof.

Among these, those that can be processed into a thin shape, are lightweight, and have excellent moisture resistance are preferred. The thickness of the metal layer can shield moisture and allow the package shape to withstand high temperatures (e.g. 215℃~260℃).
The thickness may be sufficient as long as it does not deform at temperatures (°C). Typically, the metal layer has a thickness of 5 microns or more.

In order to produce a package material by coating both sides of the metal layer with the resin layer, there are two methods: a method of dissolving the resin in a solvent and applying it to the metal layer; a method of heating and applying the resin to the metal layer without a solvent;
Depending on the thickness of the resin layer, a method of forming a resin layer on a metal layer using a powder coating method, a method of heat-sealing a film-molded or compression-molded resin to a metal layer, or a method of integral injection molding are available. Can be adopted as appropriate.

By the way, in the present invention, the above-mentioned package material is arranged so as to surround the semiconductor element and is bonded under heat and pressure. To this end, as will be described in more detail below with reference to the drawings, the package material is preferably processed in advance into a box shape having flanges at the open edges. Such processing can be performed by metal processing methods such as integral punching and blow molding using superplastic metal. This metal processing can be performed before or after forming the resin layer.

Such a box-shaped packaging material can have four parts sized and shaped so that, when placed, they do not come into contact with the semiconductor element and the bonding wires.

The thermocompression bonding is performed in such a manner that the coating resin layer is softened or melted at its end portion (the flange portion of the box-shaped package material) by heating and is then press-bonded. Heating methods include plate heating, infrared heating, etc. It is preferable to heat and press so that pressure is applied only to the periphery of the package material, so that the lead frame is not deformed and the metal layer of the package material is This is done without touching the frame. In addition, in order to further ensure that the metal layer is prevented from coming into contact with the lead frame, components such as an insulating inorganic filler that serves as a spacer such as a spherical filler may be added to the resin that covers the metal layer. . Further, it is preferable that the heat compression bonding be performed in an inert gas atmosphere or under vacuum in order to further improve moisture resistance reliability.

The resin-sealed semiconductor device according to the present invention has a configuration in which a semiconductor element is sealed on one side with the box-shaped package material, and a similar metal layer in which both sides of the box-shaped package material are coated with the same resin. It is used in combination with a flat package material, and includes a form in which a semiconductor element is sealed from both sides by both.

These forms are selected depending on the mounting state of the semiconductor element. Note that the internal hollow portion of the sealed semiconductor device of the present invention may be filled with a resin or the like that does not adversely affect the semiconductor element and the bonding wire.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

Identical parts are indicated by the same number throughout the figures.

FIG. 1 shows a cross section of an example of a sealed semiconductor device according to the present invention. As shown in the figure, a semiconductor element 19 is placed on a die pad 2o of a lead frame, and an electrode on the upper surface is bonded to a lead 22 by a wire 21. The semiconductor element 19 has a box shape with resin layers 12 and 13 formed on both sides of a metal layer 13. A flat package material 1 comprising a package material 14 and a similar metal layer 15 covered with similar resin layers 16 and 17.
8 and are sealed so as to be sandwiched between them.

The upper box-shaped packaging material 14 has a flange portion 14a at its open edge, and at the flange portion 14a,
It is adhesively bonded to the lead 22 by the resin of the resin layer.

Further, the lower flat package material 18 is adhesively bonded to the leads 22 at its ends by the resin of the resin layer. Note that the element 19 and the bonding wire 21 do not contact the box-shaped package material 14 and are hollow inside.

A method for manufacturing such a sealed semiconductor device will be explained with reference to FIG. 2. The box-shaped package material 14 shown in FIG. 2(a) is attached to the semiconductor element 19 shown in FIG. 2(b). Place it so that it surrounds it. semiconductor element 19,
The die pad 20 and leads 22 are placed on the flat package material 18 shown in FIG. 2(c). In this state, the peripheral portions of both package materials 14 and 18 are heat-pressed by the method described above. In this way, the sealed semiconductor device shown in FIG. 1 is obtained.

FIG. 3 shows a T A B bonded to a film carrier 32 by a bump 31
edBonding ) type semiconductor element 19 to the upper flat package material! 8 and the lower box-shaped cage material 14 are sealed at the film carrier 32 portion.

Such a sealed semiconductor device includes a semiconductor element shown in FIG. 4(b) which is made of a box-shaped package material 14 shown in FIG. 4(a) and a flat package material 18 shown in FIG. 4(c). 19 is sandwiched between film carriers 32, and the peripheral portions of both packaging materials 14 and 18 are heat-pressed in the manner described.

FIG. 5 shows a semiconductor element 19 mounted on a substrate 51 and having an upper surface electrode bonded to a substrate electrode 52 with a wire 21.
An example of sealing is shown below. In this sealed semiconductor device, sealing is performed such that a box-shaped package material 14 surrounds the semiconductor element 19, wires 21, and electrodes 52, without using a flat package material.

This sealed semiconductor device uses a box-shaped package material shown in FIG.
9 is sealed together with the bonding wire 21 and the electrode 52 so as to surround it. In this case, box-shaped packaging material 1
4 is heated and pressed onto the surface of the substrate 51 at its flange portion 14a.

(Function) According to the present invention, since the semiconductor element is sealed by heat-pressing so as to surround the semiconductor element with a package material in which both sides of a metal layer are covered with a resin layer, moisture does not enter into the inside of the package. can be suppressed by the metal layer. As a result, a sealed semiconductor device with excellent moisture resistance and reliability can be obtained without cracking of the sealing resin layer due to rapid vaporization of a small amount of residual moisture during heating during mounting. Since both surfaces of the metal layer are covered with resin layers, malfunction can be prevented even if internal bonding wires or the like touch the package material, or even if pins or the like touch from the outside. Further, since the sealed semiconductor device of the present invention can be manufactured by heat-pressing using the above-mentioned package material, it can be molded in a shorter time than with transfer molding, and can be manufactured easily.

(Example) Examples of the present invention will be described below along with comparative examples.

In both the following Examples and Comparative Examples, the die pad size is 15.5 s as a semiconductor element to be sealed.
The semiconductor element (chip size 15
m5+ angle, passivation: surface polyimide film) was used. In addition, unless otherwise specified, in the following Examples and Comparative Examples, the shape of the obtained package is 321
It was 1sX 32+amX 3.6+am.

Example 1 A 100 μ-thick PKS (polyketone sulfide resin) film (manufactured by Kureha Chemical Co., Ltd.) was adhered to both sides of a 400 μ-thick aluminum plate by heat fusion, and this was shown in Figure 2 (a). It was processed into the box-shaped package material shown. Further, a flat package material shown in FIG. 2(c) was produced using the same aluminum plate and resin film. These packaging materials were used to encapsulate semiconductor devices as described with respect to FIG. The heat compression bonding conditions are as follows:
Pressure bonding was carried out for 20 seconds at a pressure of 5 kg/cm2 and a temperature of 280°C.

Example 2 A phenol-curing epoxy resin (catalyst nitriphenylphosphine) containing a silicone rubber-based low stress imparting agent was B-staged on both sides of an aluminum plate by roll kneading and adjusted to a thickness of 100 μ- with a solvent. A sealed semiconductor device was manufactured in the same manner as in Example 1, except that the package material was coated to produce a box-shaped and flat-plate package material.

Example 3 A sealed semiconductor device was manufactured in the same manner as in Example 2, except that an epoxy resin-modified maleimide resin (phenyl ether-based amine crosslinked) was used as the coating resin.

Example 4 A sealed semiconductor device was manufactured in the same manner as in Example 2, except that a 100 μm-thick copper plate was used instead of the aluminum plate.

Example 5 A sealed semiconductor device was manufactured in the same manner as in Example 4 except that the package thickness was changed from 3.8 ms to 2.0 am.

Example 6 A sealed semiconductor device was manufactured in the same manner as in Example 4, except that the thickness of the cage was changed from 3.6 mm to 1.0 mm.

Example 7 PP was applied on both sides of an aluminum plate with a thickness of 400 μm.
Each was coated with S (polyphenylene sulfide resin, manufactured by Phillips) to a thickness of 100 μm, and processed into a box-shaped package material as shown in FIG. 2(a). In addition, using the same aluminum plate and resin, Figure 2 (c
A flat package material shown in ) was prepared. These packaging materials were used to encapsulate semiconductor devices as described with respect to FIG. The heat compression bonding conditions are a pressure of 5 kg/c.
12. Pressure bonding was performed at a temperature of 400° C. for 20 seconds.

Comparative Example 1 A sealed semiconductor device was manufactured in the same manner as in Example 1 using only a PKS molded product without using an aluminum plate. The heat-press bonding conditions were a pressure of 5 kg/eei2 and a temperature of 280° C. for 60 seconds.

Comparative Example 2 Using the phenol-curable epoxy resin used in Example 2 mixed with 75% filler, a semiconductor element was encapsulated with the resin by molding at 180° C. for 3 minutes by transfer molding. After-cure was performed at 180°C for 4 hours.

Comparative Example 3 A box-shaped package material having the shape shown in FIG. 2(a) was made of Kovar alloy, and a flat package material having the shape shown in FIG. 2(c) was made of alumina ceramic. was sealed. Note that an epoxy resin adhesive was used as the adhesive instead of low melting point glass, and heat and pressure bonding was carried out at a pressure of 5 kg/cm 2 and a temperature of 180° C. for 20 seconds.

Regarding the sealed semiconductor devices of Examples 1 to 7 and Comparative Examples 1 to 3 manufactured as described above, the temperature was 85°C and the relative humidity was 85°C.
% for 200 hours and measured the water absorption rate.
vPS treatment (paper phase reflow treatment) was performed twice at 5° C. for 1 minute, and the appearance was observed immediately after the vPS treatment. Furthermore, a moisture resistance reliability test was conducted in a pressure cooker at a temperature of 128° C. and a pressure of 2.5 atm to investigate the occurrence of defective products. These results are shown in Table 1 below. In addition, Example 1~
Table 1 also shows the time required for sealing during manufacturing of the sealed semiconductor devices of Comparative Examples 1 to 7 and Comparative Examples 1 to 3.

As is clear from Table 1, the sealed semiconductor devices of Examples 1 to 7 have metal layers, so moisture intrusion is suppressed, and the water absorption rate is lower than that of the sealed semiconductor devices of Comparative Examples 1 to 2. .

Moreover, the sealed semiconductor devices of Examples 1 to 7 are the same as those of Comparative Examples 1 to 7.
It can be seen that compared to the sealed semiconductor device No. 3, the appearance after vPS processing is excellent and the moisture resistance reliability is also excellent. Furthermore, the sealed semiconductor devices of Examples 1 to 7 require a shorter time for sealing than transfer molding or other methods.

[Effects of the Invention] As detailed above, according to the present invention, moisture intrusion into the inside of the package is suppressed, the problem of cracking of the resin during heating during mounting does not occur, and airtightness and post-mounting are improved. This encapsulation has excellent moisture resistance and reliability, and is faster and easier to manufacture than resin encapsulation using the conventional transfer molding method, and is fully compatible with the future trend toward larger and thinner semiconductor devices. A stop type semiconductor device can be provided.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a sealed semiconductor device of the present invention, FIG. 2 is a cross-sectional view for explaining a method for manufacturing the sealed semiconductor device shown in FIG. 1, and FIG. FIG. 4 is a cross-sectional view for explaining a method of manufacturing the sealed semiconductor device shown in FIG. 3, and FIG. 5 is a cross-sectional view of another sealed semiconductor device of the invention. FIG. 6 is a cross-sectional view for explaining a method for manufacturing the sealed semiconductor device shown in FIG.

Claims (1)

[Claims] 1. A sealed semiconductor device characterized in that a package material in which both sides of a metal layer are covered with a resin layer surrounds a semiconductor element, and the semiconductor element is sealed by heat and pressure bonding.