JPH0864710A - Metallic foil material for semiconductor package coating and semiconductor device - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] To improve the releasability between the adhesive layer for temporary fixing and the die molding surface when manufacturing a semiconductor device in which the resin package surface is covered with a metal foil material. In addition, the present invention provides a metal foil material capable of reducing adhesive residue on the molding surface of the adhesive, and is also excellent in moisture resistance, solder resistance and thermal shock resistance covered by the metal foil material. Realize a highly reliable semiconductor device. [Structure] In a semiconductor package coating metal foil material 3 fixed to the surface of a semiconductor package formed by sealing a semiconductor element 4 with a resin 6, the surface has a tensile shear adhesive strength to a # 280 polished stainless steel plate. 0.08-12.
It is set to 0 kgf / cm ² . Then, at the time of molding, the metal foil material 3 is temporarily fixed on the molds 1 and 2 via the adhesive layer 8 and then the sealing resin 6 is injected into the mold to mold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal foil material which is fixed to the surface of a semiconductor package formed by sealing a semiconductor element with resin and covers the surface of the package, and a semiconductor device including the same.

[0002]

2. Description of the Related Art Conventionally, semiconductor devices such as transistors, ICs and LSIs have been encapsulated in a ceramic package or the like to be a semiconductor device. However, from the viewpoint of cost and mass productivity, resin encapsulation using a plastic package is preferred. It is becoming mainstream. Epoxy resin has been used for this type of resin encapsulation and has achieved good results.

On the other hand, while technological innovations in the semiconductor device field have increased the degree of integration and increased the size of elements, there is a strong demand for miniaturization and thinning of packages. Therefore, resin materials for encapsulation are required. The volume ratio occupying is decreasing. Under these circumstances, the sealing material is required to have various characteristics such as characteristics capable of reducing the thermal stress of the semiconductor device, humidity resistance reliability, and reliability against a thermal shock test. In addition, surface mounting is becoming the main method of mounting semiconductor packages on wiring boards. Therefore, even if a semiconductor package is dipped in a solder melt while absorbing moisture, the package will not crack or swell. Is required.

To meet these demands, it has been studied to reduce the thermal stress by modifying the epoxy resin with a silicone compound in order to improve the thermal shock resistance evaluated by the TCT test. Further, improvement of adhesion with a lead frame has been studied in order to improve crack resistance at the time of immersion in a solder melt, but the effect is still insufficient.

Therefore, the inventors of the present invention, in order to obtain a highly reliable semiconductor device which is excellent in moisture resistance, solder resistance, and thermal shock resistance even if the plastic package is made thin, uses a metal foil to form a plastic package surface. Is proposed, as the method, when molding the resin for sealing the semiconductor element using a mold, after temporarily fixing the metal foil material to the molding surface of the mold, inject the resin, It proposes a method of directly adhering the metal foil material to the surface of the plastic package by molding. In that case, as a temporary fixing method of the metal foil material to the mold forming surface, an adhesive layer is provided on the metal foil material surface which is in contact with the mold forming surface to temporarily fix it, or a vacuum is provided without providing the adhesive layer. There is a method of temporarily fixing by physical means such as adsorption, magnetic force, and gravity.

[0006]

However, after the metal foil material provided with the adhesive layer for temporary fixing as described above is temporarily fixed to the mold through the adhesive layer, the sealing resin is used. Is injected and molded to manufacture a semiconductor device in which the resin package surface is covered with a metal foil material, the releasability between the temporary fixing adhesive layer and the die molding surface, and the temporary fixing adhesive Dirt on the mold surface due to adhesive residue on the mold (some or all of the temporary fixing adhesive remains attached to the mold surface after the molded resin package is removed from the mold) Has become.

The present invention addresses such a problem. When manufacturing a semiconductor device in which the resin package surface is covered with a metal foil material, the temporary fixing adhesive layer and the mold molding surface are separated from each other. It is an object of the present invention to provide a metal foil material capable of improving adhesiveness and reducing adhesive residue on the molding surface of the adhesive, and also to provide a semiconductor device covered with the metal foil material. .

[0008]

In order to achieve the above object, the metal foil material and the semiconductor device of the present invention are characterized by having the following configurations, respectively.

That is, the metal foil material of the present invention is a metal foil material for covering a semiconductor package, which is fixed to the surface of a semiconductor package formed by sealing a semiconductor element with a resin,
The surface on the side in contact with the die molding surface has a tensile shear adhesive strength to a # 280 polished stainless steel plate of 0.08 to 12.
An adhesive layer for temporary fixing of 0 kgf / cm ² is provided. Here, the tensile shear adhesive strength of the adhesive referred to in the present invention refers to # 28 according to JIS K6850.
0 means a value measured at room temperature (about 25 ° C.) under a condition of a tension rate of 300 mm / min using a test piece to which a 0-polished stainless steel plate is adhered.

The semiconductor device of the present invention is characterized in that the above-mentioned metal foil material is fixed to the surface of the semiconductor package. The metal foil material must have a melting point of 300 ° C. or higher so that it can withstand the resin temperature and mold temperature during molding, but the type of metal is not particularly limited as long as this condition is satisfied. . Examples of such materials include aluminum, stainless steel, copper, nickel and the like. The thickness of this type of metal foil material is in the range of 1 μm to 300 μm, preferably 5 μm to 2
It is set in the range of 00 μm. If the thickness is 1 μm or less, it is difficult to handle, and if it exceeds 300 μm, the thickness of the resin that wraps the semiconductor element decreases, and the fluidity of the resin during injection deteriorates.

Further, as the adhesive layer for temporary fixing,
Since the temperature of the mold becomes high, for example, a wax, a phenoxy resin, an ethylene-vinyl acetate copolymer, a heat-melting adhesive such as a polyester resin, or a thermosetting resin such as an epoxy resin can be used. The thickness of the adhesive layer is preferably in the range of 5 μm to 100 μm. Note that this type of adhesive layer also includes a pressure-sensitive adhesive layer.

The adhesive used for this adhesive layer is one that can be temporarily fixed to a mold heated to a high temperature and does not cause the metal foil material to flow due to the pressure of the injected resin when the sealing resin is injected. There must be. In addition, after the package is molded, the interface between the metal mold surface and the adhesive layer does not cause cohesive failure in the adhesive layer or the interface between the metal foil and the adhesive layer. It must be possible to take out the semiconductor device from the mold in a good condition. In order to meet these requirements, the present invention uses # 28 as an adhesive forming the temporary fixing adhesive layer.
0 Tensile shear adhesive strength to polished stainless steel plate is 0.0
8 to 12.0 kgf / cm ² , preferably 0.10 to
5.0 kgf / cm ² , practically 0.2-1.0 kg
Use an adhesive in the range of f / cm ² .

On the other hand, in the semiconductor device of the present invention, for example, when the resin for sealing the semiconductor element is molded by transfer molding or injection molding using a mold, the metal foil material is formed on the molding surface of the mold. It can be obtained by temporarily fixing and then injecting a resin into a mold to mold the resin. In this case, the term “temporary fixing” means a fixing property that does not fall off even when the mold is opened and closed and that can be easily separated from the mold after resin molding. In the above-mentioned semiconductor package coating metal foil material of the present invention, the adhesive layer for temporary fixing is provided on the surface in contact with the mold forming surface, and therefore, the adhesive layer for temporary fixing to the mold forming surface is provided through the surface. Fixation can be done.

For reference, an example of a method of manufacturing a semiconductor device using the metal foil material of the present invention will be described with reference to the drawings. First, as shown in FIG. 1A, the metal foil material 3 is temporarily fixed to the molding surfaces of the opened molds 1 and 2. Then, as shown in FIG. 3B, the semiconductor element 4 to be sealed, together with the lead frame 5, is supplied. Next, as shown in FIG. 1C, after closing the molds 1 and 2, a resin 6 as a sealing material is injected into the molds to be molded and cured. After the curing, the molds 1 and 2 are opened, and the semiconductor device in which the metal foil material 3 is fixed to the surface of the resin 6 is taken out as shown in FIG.

FIG. 2 is a schematic enlarged view showing a structural example of the metal foil material 3. In the metal foil material 3 exemplified here,
Adhesive layer 8 for temporarily fixing to the molding surface of one side of the metal foil 7.
Is provided. This is the resin 6 in the molds 1 and 2.
This is for preventing the set position of the metal foil material 3 from changing during the injection of the resin and preventing the resin 6 from flowing between the metal foil material 3 and the die molding surface. Although not shown, an undercoat agent layer for anchor (for example, a layer made of a silane coupling agent) for enhancing the adhesiveness with the sealing resin material may be provided on the back surface of the metal foil 7.

FIG. 3 shows an example of the structure of the semiconductor device of the present invention. The external characteristic of the semiconductor device illustrated here is that the surface 9 of the metal foil 7 is depressed more than the surrounding resin surface 10. Note that FIGS. 2D and 3 show an example of the semiconductor device of the present invention, and it goes without saying that the semiconductor device of the present invention is not limited to the one shown. For example, in the semiconductor device shown in these figures, the metal foil material 3 or the metal foil 7 is fixed to both surfaces of the semiconductor package, but in the semiconductor device of the present invention, the metal foil material or metal is provided only on one surface of the semiconductor package. Also included are those in which the foil is not fixed.

A thermosetting resin is used as the resin material for sealing the semiconductor element, and examples thereof include epoxy resin, phenol resin, urea resin, melamine resin, polyester resin, diallyl phthalate resin, and polyphenylene sulfide. Among these, it is preferable to use an epoxy resin. In that case, the epoxy resin is mixed with a conventionally known additive such as a curing agent, a curing accelerator and a filler, and used as an epoxy resin composition. Further, the thermosetting resin may contain 0.01 to 5% by weight of a releasing agent such as silicone oil or wax having a releasing effect on the mold.

When a plastic package is coated with the above metal foil material, 20% of the package surface area is covered.
It is preferable to coat the above, especially 80% or more. This is because the coating of 20% or more improves the reliability of the obtained semiconductor device in the TCT test and the crack resistance when immersed in the solder melt, and particularly when 80% or more, such performance is remarkably improved. .

Further, the individual identification information such as the product name and manufacturing lot number of the semiconductor device is recorded on the surface of the plastic package before or after molding, but in the present invention, it may be recorded on the surface of the metal foil. preferable. This individual identification information may be recorded by a general method such as laser marking or stamping. Also,
When recording a large amount of information, it is preferable to use a photosensitive resin. In this method, a photosensitive resin layer is formed on a metal foil using a photosensitive resin, and light is applied to the photosensitive resin layer by a method such as an ultraviolet (UV) exposure method through a mask film to record individual identification information. Is the method. Examples of the photosensitive resin include acrylic-based, epoxy-based, and polyimide-based photosensitive resins. Among these, from the viewpoint of heat resistance,
It is preferable to use a polyimide-based photosensitive resin. The thickness of the recording layer is 0.1 to 20 μm, preferably 1
It is set in the range of ˜5 μm. When the individual identification information is recorded on the surface of the metal foil, it is preferable to use a metal foil having the following characteristics (A) or (B) as the metal foil. (A) The glossiness of the metal foil surface is in the range of 70 to 250% according to JIS Z8741. (B) The average surface roughness is 0.1 to 10 μm. By using such a metal foil, the influence of excess reflected light is removed, and individual identification information can be accurately recognized from a wide angle. Further, in order to obtain more contrast, a color material layer may be provided on the metal foil.

[0020]

The metal foil material of the present invention, when the semiconductor element is sealed with resin and the semiconductor package is molded and processed, is injected with the resin while being temporarily fixed to the molding surface of the mold.
It is fixed to the surface of the package. In that case, in the metal foil material of the present invention, the tensile shear adhesive strength to the # 280 polished stainless steel plate is 0.08 to 1 on the surface thereof.
Since the adhesive layer having a pressure of 2.0 kgf / cm ² is provided, it is possible to temporarily fix the adhesive layer to the molding surface through the surface of the adhesive layer. It does not cause flow. In addition, after molding, without causing cohesive failure in the adhesive layer or interface failure between the metal foil and the adhesive layer, interface failure between the mold surface and the adhesive layer causes The semiconductor device can be released from the mold. Therefore, the releasability from the mold after molding is improved, and the problem of stains on the mold due to the adhesive residue on the adhesive layer is eliminated.

The metal foil material fixed to the package surface in this way covers the package surface and prevents moisture absorption of the resin. In addition, the coating of the metal foil material improves the characteristics evaluated in the TCT test and extends the life. Further, since the metal foil material reinforces the package and relaxes the thermal shock resistance, the occurrence of the package crack can be prevented even when the package is immersed in the solder melt.

When individual identification information is recorded on the surface of the metal foil material, it can be used as an information recording label. In that case, if a recording layer is formed of a photosensitive resin on the surface of the metal foil material, a large amount of information can be recorded and automatic recognition can be performed. Further, by using the metal foil material having a specific glossiness or surface roughness, it is possible to remove the influence of extra reflected light, etc., so that the individual identification information can be accurately recognized. Becomes

[0023]

EXAMPLES Examples of the present invention will be described below together with comparative examples. Using an epoxy resin composition, a semiconductor element was resin-sealed by transfer molding (conditions: 175 ° C. × 2 minutes) to produce a semiconductor device in which a metal foil material was fixed to the package surface.

In that case, as the metal foil material, the substrate thickness 40
A temporary fixing adhesive layer (thickness: 50 μm), which will be described later, is provided on an aluminum material having a thickness of μm. It was temporarily fixed on the surface (see FIG. 1A). Next, the semiconductor element was set in the mold, and the resin for sealing was introduced into the mold by a usual method to perform molding (FIG. 1).
(B) and (C)). In the semiconductor device thus obtained, as shown in FIG. 3, the surface of the aluminum foil was depressed more than the surface of the surrounding sealing resin.

The package manufactured here is an 80-pin 4-direction flat package (80-pin QFP, size 20 mm × 14 mm × 2 mm), and the die pad size is 8 mm × 8 mm. The aluminum material used had a size of 18 mm × 12 mm and was fixed on both sides of the package.

In the above cases, the following aluminum materials were used as the metal foil material in each of the examples and comparative examples. [Example 1] Tensile shear bond strength to a # 280 polished stainless steel plate on one side of an aluminum foil was 0.10 kg.
An aluminum material provided with an adhesive of f / cm ² as an adhesive layer for temporarily fixing the metal foil material to a mold. [Example 2] Tensile shear adhesive strength to a # 280 polished stainless steel plate on one surface of an aluminum foil was 10 kgf /
An aluminum material provided with an adhesive of cm ² as an adhesive layer for temporarily fixing the metal foil material to a mold. [Comparative Example 1] One side of aluminum foil has a tensile shear adhesive strength of 0.05 kg to a # 280 polished stainless steel plate.
An aluminum material provided with an adhesive of f / cm ² as an adhesive layer for temporarily fixing the metal foil material to a mold. [Comparative Example 2] The tensile shear adhesive strength to a # 280 polished stainless steel plate was 15 kgf / on one side of an aluminum foil.
An aluminum material provided with an adhesive of cm ² as an adhesive layer for temporarily fixing the metal foil material to a mold.

Here, the value indicated as the tensile shear adhesive strength of the adhesive is based on JIS K6850 as described above, and a test piece to which a # 280 polished stainless steel plate is adhered is
It is a value measured by pulling at a pulling speed of 300 mm / min at room temperature (about 25 ° C.).

In each of Examples 1 and 2 and Comparative Examples 1 and 2, the aluminum material was temporarily fixed on the mold via the adhesive layer, and then a sealing resin was injected into the mold. A semiconductor device was molded, and adhesive residue (mold stain) on the mold due to cohesive failure of the temporary fixing adhesive layer at that time and mold releasability from the mold were observed. In addition, molding defects of the semiconductor device due to defective adhesion of the aluminum material to the mold during molding were examined. The results are shown in Table 1.

[0029]

[Table 1]

As shown in the table, in each of the examples of the present invention, there was no molding defect due to mold stains due to the adhesive layer or adhesion failure of the mold, and the mold releasability from the mold was good. Met. On the other hand, in Comparative Example 1, there were many molding defects due to poor adhesion of the adhesive layer to the mold, and in Comparative Example 2, the mold stain due to the adhesive layer was significant and the mold was separated from the mold. The sex was also poor. Thus, according to Embodiments 1 and 2 of the present invention, it is possible to effectively prevent the mold from being soiled by the adhesive layer and poorly adhered to the mold, and the mold release property from the mold is good. It was confirmed that

[0031]

As described above, according to the present invention, when a semiconductor element is sealed with a resin and a semiconductor package is molded and processed, a predetermined adhesive layer provided on the surface of the metal foil material is interposed. Can be temporarily fixed to the molding surface of the mold and the releasability from the mold after molding can be improved, so that the mold can be prevented from becoming dirty due to adhesive residue on the adhesive layer. it can.

The metal foil material of the present invention adhered to the surface of the package during the molding process of the sealing resin covers the surface of the package to prevent the resin from absorbing moisture. In addition, the coating of this metal foil material improves the characteristics of the semiconductor device evaluated in the TCT test and prolongs its life, and the metal foil material reinforces the package to reduce the thermal shock resistance. Even when immersed, the generation of package cracks can be prevented.

Further, when the individual identification information is recorded on the surface of the metal foil material, this can be used as an information recording label. In that case, if a recording layer is formed of a photosensitive resin on the surface of the metal foil material, a large amount of information can be recorded and automatic recognition can be performed. Further, by using the metal foil material having a specific glossiness or surface roughness, it is possible to remove the influence of extra reflected light, etc., so that the individual identification information can be accurately recognized. Becomes

[Brief description of drawings]

FIG. 1 is a process diagram used to explain an example of a manufacturing method of a semiconductor device of the present invention.

FIG. 2 is a diagram schematically showing an example of the structure of a metal foil material for coating a semiconductor package of the present invention.

FIG. 3 is a sectional view schematically showing an example of the structure of the semiconductor device of the present invention.

[Explanation of symbols]

 1, 2 ... Mold 3 ... Metal foil material (aluminum material) 4 ... Semiconductor element 6 ... Sealing resin 8 ... Adhesive layer

Claims (4)

[Claims] 1. A metal foil material fixed to the surface of a semiconductor package formed by sealing a semiconductor element with a resin, the surface of which has a tensile shear adhesive strength of 0.08 to a # 280 polished stainless steel plate. A metal foil material for coating a semiconductor package, which is provided with an adhesive layer having a thickness of ˜12.0 kgf / cm ² . 2. A semiconductor package surface is obtained by temporarily fixing a resin for sealing a semiconductor element to a molding surface of the mold when the resin is molded and then injecting and molding the resin into the mold. Which is a metal foil material fixed to the
As an adhesive layer for temporary fixing to the die molding surface, the tensile shear adhesive strength to a # 280 polished stainless steel plate is 0.08 to
A metal foil material for coating a semiconductor package, which is provided with an adhesive layer of 12.0 kgf / cm ² . 3. The metal foil material for coating a semiconductor package according to claim 1, wherein the label has a surface on which individual identification information regarding a semiconductor package to be adhered is recorded. 4. A semiconductor device, wherein the metal foil material according to claim 1 is fixed to the surface of a semiconductor package.