JPH02303052A - Semiconductor package - Google Patents

Abstract

PURPOSE:To increase mechanical strength and heat dissipation, and obtain a small-sized package having electromagnetic shielding effect which is easily manufactured, by sealing a metal cap for a semiconductor chip arranged on a metal substrate via high melting point glass, and necessary leads by using low melting point glass. CONSTITUTION:A metal cap 17 seals a semiconductor chip 11 mounted and arranged on high melting point glass 13 on a metal substrate 12 of low thermal expansion alloy. Said cap 17 is seal-bonded together with the following by using low melting point glass 18; inner leads 15 of Al or Cu thin film connected with bonding wires 16, and outer leads 14 connected with the inner leads 15. By this constitution wherein the seal is performed by using the metal cap and low melting point glass without using a plastic cap, mechanical strength and heat dissipation are increased, and electromagnetic shielding effect is realized. Further a small-sized and low cost semiconductor package is easily manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a semiconductor package using a low thermal expansion alloy plate as a substrate on which a semiconductor chip is placed, and in which a glass insulating layer is provided on the substrate on which inner and outer lead members are placed. For example, the present invention relates to a semiconductor package that has excellent mechanical strength, is easy to handle, has an electromagnetic shielding effect, and has excellent heat dissipation properties by sealing a cap made of a low thermal expansion alloy with glass.

BACKGROUND ART Conventionally, a so-called plastic package, as shown in FIG. 6, in which a semiconductor chip (hereinafter referred to as a chip) is sealed with plastic, has been widely used as a semiconductor package.

That is, the plastic package (1) contains the chip (
2) is placed on the island (4) formed in the center of the lead frame (3), fixed with brazing material, adhesive, solder, etc., and bonded to the stitch (5) (inner lead part). It has a configuration in which it is electrically connected via a wire (6), and the periphery is further sealed with a resin (7).

Plastic packages are easy to mass-produce and are inexpensive, but since the plastic itself is inherently hygroscopic, the sealing is not perfect and is easily affected by the surrounding environment, reducing chip reliability and increasing integration. It is said that it cannot be used in high-performance chip packages that require multi-functionality.

Semiconductor package chips, such as LSI and ULSI for large computers, are moving toward higher integration and faster calculation speed, and the amount of heat generated due to the increase in power consumption during operation has become extremely large. There is. Additionally, there is a strong demand for semiconductor packages to have a larger number of bins and to be smaller.

In the resin-sealed package (1), as shown in FIG. 6, the lead frame not only serves as a path for electrical connection to the outside of the semiconductor chip, but also as a dissipation path for heat generated in the chip (2). plays an important role as

Therefore, the lead frame (3) is desired to be made of a material with good thermal conductivity in order to dissipate the heat generated from the chip to the outside of the package.

On the other hand, peeling of the adhesive interface between the chip (2) and the island (4) and cracks observed in the resin (7) are caused by the chip (
2) and the difference in thermal expansion coefficient between the sealing resin (7) and the lead frame (3).In order to prevent this, it is necessary to Matching the coefficient of thermal expansion with the frame (3) is essential.

As described above, plastic packages have poor heat dissipation properties, are limited in lead frame materials, and are particularly unable to reduce electrical resistance.

Furthermore, since plastic packages do not have an electromagnetic shielding effect, there is a problem in that they cannot prevent the influence of external noise.

Purpose of the Invention The present invention solves the above-mentioned problems of plastic packaging, has excellent mechanical strength and heat dissipation, has an electromagnetic shielding effect, and satisfies the recent demands for multi-bin size and miniaturization. The aim is to provide semiconductor packages that are easy to mass produce.

Summary of the Invention This invention uses a low thermal expansion alloy for the substrate on which the chip is placed or the cap that encloses the chip, and coats high-melting point glass as an insulating layer on the substrate, and provides internal leads for wire bonding to the chip. The above object has been achieved by using A1 or Cu thin films and forming them using thin film forming technology to facilitate connection with external leads, and by integrating these substrates and caps with low melting point glass.

That is, the present invention comprises a metal substrate made of a low thermal expansion alloy coated with a high melting point glass insulating layer at least at the sealing part and the part where the inner and outer lead members are to be disposed, and an Al or Cu thin film formed on the upper surface of the substrate insulating layer. an external lead consisting of a lead frame which is laminated and connected to the internal lead; and a semiconductor chip fixed to the surface of the metal substrate, which is encapsulated and sealed to the metal substrate via a low-melting glass; The present invention is a semiconductor package characterized by being comprised of a cap that holds a lead frame.

Further, the present invention includes a metal substrate made of a low thermal expansion alloy coated with a high melting point glass insulating layer at least at the sealing portion and the portion where the inner and outer lead members are to be disposed, and an Al or Cu thin film formed on the upper surface of the substrate insulating layer. an internal lead consisting of an internal lead, and an external lead consisting of a lead bin that penetrates the metal substrate and is erected through high melting point glass;
This semiconductor package is characterized in that it includes a cap that encloses a semiconductor chip fixed to a surface of a metal substrate and seals the metal substrate through a low-melting glass.

Preferred Embodiment The substrate material used in this invention is Fe-Cr alloy (
18Cr-Fe, etc.), Fe-Ni-Cr alloys (42N
i-6Cr-Fe, etc.), Fe-Ni alloy (42Ni-
Fe, etc.), Fe-Ni-Co alloy (29Ni-16C
Known low thermal expansion alloys such as o-Fe, etc.) can be used.

In particular, it is desirable to select an optimal alloy in accordance with the coefficient of thermal expansion of high melting point glass, chips, etc., which will be described later.

In addition, in consideration of heat dissipation properties, the substrate material may be a cladding material of the above-mentioned low thermal expansion alloy in which Cu, Cu alloy, etc. with good thermal conductivity is arranged in the intermediate layer, such as Invar lCu/Invar,
Kovar/Cu/Kovar can also be used.

As the high melting point glass to be adhered to the upper surface of the above low thermal expansion alloy, PB glass etc. can be used. Considering heat generation from the chip, the difference in thermal expansion coefficient between the chip and the substrate material is small, and the mechanical strength is low. It is desirable that the bonding temperature is high, and that the wettability with Al and Cu of the lead member is good.

In this invention, the high melting point glass has a high melting point relative to the low melting point glass used for sealing with the cap, and may be any high melting point glass that does not melt during sealing. It is preferable to appropriately select the melting and softening temperature of the glass necessary for adhesion, taking into consideration the characteristics of the glass and manufacturing workability.

Furthermore, depending on the method used to form the metal thin film wiring that will become the internal leads (described later), high-melting point glass may be coated with corrosion-resistant material to prevent it from reacting with the etching solution. It is desirable to select an excellent one.

When coating a low thermal expansion alloy with a high melting point glass, if an external lead member is to be attached at the same time when the high melting point glass is fired, a glass powder of a predetermined particle size (usually 200 mesh to 300 mesh) must be used in consideration of the thickness of the lead member. Known techniques such as applying the film to a required thickness by screen printing, electrodeposition, etc., and then baking and integrating the film can be employed.

In addition, if a method is adopted in which a metal thin film wiring of an internal lead is formed on a metal substrate in advance, and then an external lead member is placed on the end of the wiring and fixed by heating and diffusing, the above-mentioned screen printing, electrodeposition In addition to the above, it is also possible to adopt a method in which a high melting point glass plate is placed on the upper surface of the substrate and then heated and pressurized to a temperature higher than the softening temperature of the high melting point glass to integrate them.

The ratio A/B between the thickness A) of the low thermal expansion alloy plate of the metal substrate and the thickness B) of the high melting point glass is selected taking into consideration dielectric strength voltage, mutual coefficient of thermal expansion, thermal conductivity, etc. Usually 1010.
A range of 5 to 1015 is desirable.

The insulating layer of high-melting point glass does not necessarily need to be provided on the entire surface of the metal substrate, but it is better to provide it at least on the sealing part and on the inner and outer lead parts of the metal substrate. With this in mind, it is possible to fix the chip directly to the metal substrate.

Furthermore, in order to improve the adhesion between the low thermal expansion alloy and the high melting point glass, it is desirable to interpose an oxide film between the low thermal expansion alloy and the high melting point glass, especially when the low thermal expansion alloy contains Cr. The applicant's earlier proposal (Japanese Unexamined Patent Publication No. 6
No. 3-47955), it is possible to employ a method such as forming an oxide film mainly composed of V) Cr2O3 on the main surface of a low thermal expansion alloy by heat treatment, and then covering it with high melting point glass.

On the other hand, as the material of the cap for enclosing the chip, a known low thermal expansion alloy can be used, similar to the above-mentioned substrate material.
At this time, the cap material does not necessarily have to be the same material as the substrate material, and other side slopes such as transparent glass can also be used.

The low melting point glass for sealing the cap needs to be placed only at the sealing joint between the cap and the substrate, and the method of adhering it to the cap may be screen printing or electrodeposition followed by firing, taking into consideration workability. Known means such as doing this can be employed.

Further, in order to improve the adhesion with the low thermal expansion alloy, it is also preferable to interpose an oxide film between the low melting point glass and the low thermal expansion alloy.

The above-mentioned low melting point glass has a difference in thermal expansion coefficient and thermal conductivity with the cap material such as a low thermal expansion alloy or transparent glass, etc., and the bonding between the cap and the metal substrate is performed after chip bonding. It is desirable to set the bonding temperature as low as possible so as not to adversely affect the bonding temperature. For example, PB glass having a melting temperature of 500° C. or lower can be used.

In this invention, the internal lead can be formed by easily and precisely depositing a metal thin film wiring made of Al or Cu on the upper surface of the high melting point glass forming the insulating layer using a known thin film forming technique. is preferably about 5 to 10 pm.

In other words, for the deposition of internal leads, there is a method in which a predetermined position on the upper surface of the insulating layer is masked, Al or Cu is evaporated, and the mask material is removed again, or a method in which At or Cu is applied to the entire upper surface of the insulating layer in advance. A method may be adopted in which Cu is pasted or deposited by vapor deposition or the like, and then unnecessary portions are removed by etching.

Al and Cu of the internal leads are, for example, W, Mn-Mo
Not only is it less expensive than alloys, but it also has the advantage of being easily applicable to thin film formation techniques such as vapor deposition and etching, and can be easily wire-bonded to chips.

In addition, it has a lower electrical resistance than W, Mn-Mo alloys, etc., and can reduce heat generation during use and improve response time. In particular, in the case of Al, it has high adhesion to high melting point glass, and can significantly reduce damage and malfunction due to peeling of thin film wiring during use.

The lead frames and lead bins that are connected to the ends of the internal leads and serve as external leads can be made of a known low thermal expansion alloy similar to the material used for metal substrates and metal caps, and the outer surface of conventional lead frame materials is made of Cu. It is preferable to use a plated material having characteristics such as electrical resistance equivalent to Cu or Cu alloy.

Furthermore, if the outer lead is made of Cu, a Cu alloy, or a Cu-plated material, it has the advantage that if the inner lead is an At thin film, it can be easily integrated by heat diffusion bonding.

DISCLOSURE BASED ON THE DRAWINGS FIGS. 1 and 2 are longitudinal sectional views of the semiconductor package of the present invention. FIGS. 3 to 5 are longitudinal sectional views of main parts of the semiconductor package of the present invention.

The semiconductor package (10) shown in FIG. 1 has a metal substrate (12) on which a chip (11) is mounted at the center of the upper surface, and a high melting point glass (13) as an insulating layer on the entire surface of a low thermal expansion alloy plate.
It consists of a covered structure.

The external leads (14) provided on the high melting point glass (13) layer consist of a so-called lead frame, and the internal leads (15) similarly consist of A1 or Cu thin film wiring formed in a desired pattern on an insulating layer. One end of each is laminated and connected. Furthermore, the internal leads (15) are connected to the chip (11) with bonding wires (16).

The metal cap (17) is made of a low thermal expansion alloy.
The chip (11) placed on the metal substrate (12)
), internal leads (15) and bonding wires (16)
) and are sealed to the metal substrate (12) via a low melting point glass (18).

In the above configuration, the metal cap (17) and the metal substrate (
12), the external lead (14) and the internal lead (
15) Since they are sandwiched together, the bonding strength is high, and it is possible to prevent cracks from occurring at the bonded portion between the two, resulting in an extremely high sealing effect.

The semiconductor package (20) shown in FIG. 2 has the same configuration as the semiconductor package (10) shown in FIG. (24) and the internal lead (25) have the same structure and effect, and furthermore, the chip (21)
) In order to improve heat dissipation from the metal substrate (22), four parts are provided at the center of the upper surface of the metal substrate (22), and the chip (21) is placed thereon without covering the high melting point glass (23).

The semiconductor package (30) shown in FIG. 3 has basically the same structure as that shown in FIG. Instead, only the external lead (35) is held between the four parts.

In particular, the semiconductor package (40) shown in FIG. 4 has A1 as the internal lead (45) and C as the external lead (44).
This configuration is effective when using u or Cu alloy or a material with Cu plating on the surface. After forming a thin film of the internal lead (45) on the upper surface of the high melting point glass (43) of the metal substrate (42), In this structure, external leads (44) are stacked and integrated by heating and diffusion.

The semiconductor package (50) shown in FIG. 5 is an embodiment in which a lead bin is used for the external lead, whereas the structure shown in FIGS. 1 to 4 uses a lead frame for the external lead.

In detail, a metal substrate (52) on which a chip (51) is placed
) has a high melting point glass (53) coated as an insulating layer on the upper surface of a low expansion alloy plate, similar to each semiconductor package described above, and the external lead (54) consisting of a lead bin is, for example, preliminarily connected to the metal substrate (52). ) through the through hole formed in the high melting point glass tube (5) to ensure insulation with the metal substrate (52).
Insert the lead bottle inserted into 4a) and insert the external lead (
54) A thin film was similarly formed on the insulating layer in the desired pattern, with the upper end exposed protruding from the high melting point glass (52) layer.
Internal leads (55) made of L or Cu thin film wiring are stacked and connected. Furthermore, the internal leads (55) are connected to the chip (51) with bonding wires (56).

The metal cap (57) is formed from a low thermal expansion alloy.
Chip (51) placed on the metal substrate (52)
), internal leads (55) and bonding wires (56)
) and are sealed to the metal substrate (52) via a low melting point glass (58).

Effects of the Invention As shown above, the semiconductor package obtained by the manufacturing method of the present invention has high mechanical strength and extremely low risk of breakage because the substrate or cap is sealed with glass using a low thermal expansion alloy material. Become,
Lighter weight, smaller size, and cheaper to handle.

■Significantly improves heat dissipation compared to conventional packages.

■Enables electromagnetic shielding, reducing the effects of external noise.

■Compared to the conventional structure using only lead frames, the tip part where wire bonding is performed can be formed with high precision.
It can greatly contribute to increasing the number of bins and downsizing.

(2) Since A1 and Cu can be used, it is not only inexpensive since it does not require Au plating, etc., but also reduces electrical resistance, making it possible to reduce heat generation during use and achieve high-speed response.

Example (1) As an example, a case will be described in which a semiconductor package shown in FIG. 1 is manufactured.

42Ni-6C of 30mm x length 30mm x 0.2mm
Low thermal expansion alloy plate made of r-Fe (thermal expansion coefficient = 95~
100xlO'/°C) on the upper surface of the
Cr2 with a film thickness of 1.0 μm was heated to 1150°C in gas.
After forming an oxide film layer mainly composed of O3, PB-based high melting point glass (thermal expansion coefficient: 94xlO-7/
'C) was applied by screen printing and further baked at 800° C. to integrate them to form a metal substrate. The thickness of the high melting point glass after firing was 0.05 mm.

During the above firing, a 0.15 mm thick 4
Lead frame made of 2Ni-Fe (coefficient of thermal expansion: 5
0xlO-7/'C) was integrated into the metal substrate with the top surface exposed.

Next, an Al thin film wiring having a desired shape as an internal lead was formed by vapor deposition using a stainless steel jig as a mask material, and connected to the exposed surface of the lead frame. The thickness of the Al thin film at this time was 10 pm.

Thereafter, the chip was fixed to the upper surface of the insulating layer with an adhesive, and the chip and the Al thin film wiring were connected using an Al bonding wire.

The cap is made of a low thermal expansion alloy made of the same material as the metal substrate, and after being heat-treated to form a Cr2O3 film in advance, PB-based low melting point glass (thermal expansion coefficient: 80xlO'/
'C) is applied by screen printing, placed on the metal substrate and baked at 450'C to integrate with the metal substrate, and the Al thin film wiring and lead frame are both sandwiched by the sealing part. did.

When comparing the semiconductor package of the present invention with a conventional semiconductor package whose substrate and cap are both made of plastic as shown in Fig. 6, it was confirmed that the heat dissipation performance of the semiconductor package of the present invention was improved by about 35 to 50%. It was done.

We also confirmed that the electromagnetic shielding effect reduces the effects of external noise.

[Brief explanation of the drawing]

FIGS. 1 and 2 are longitudinal sectional views of the semiconductor package of the present invention. FIGS. 3 to 5 are longitudinal sectional views of main parts of the semiconductor package of the present invention. FIG. 6 is an explanatory longitudinal cross-sectional view of a conventional plastic package. 10. 20, 30, 40, 50... - semiconductor package, 11. 21, 31, 41, 51... chip, 12.
22,32,42.52...metal substrate, 13.23,
33,43,53...High melting point glass, 14.24,3
4,44,54...external lead, 15.25,35,
45, 55...internal lead, 16.26, 36, 46
．． 56... bonding wire, 17.27, 37,
47.57...metal cap, 18.28,38,4
8,58...Low melting point glass.

Claims (1)

[Scope of Claims] 1. A metal substrate made of a low thermal expansion alloy coated with a high melting point glass insulating layer at least at the sealing portion and the portion where the inner and outer lead members are to be disposed, and an Al or Cu thin film formed on the upper surface of the substrate insulating layer. an external lead consisting of a lead frame which is laminated and connected to the internal lead, and a semiconductor chip fixed to the surface of the metal substrate, which is encapsulated and sealed to the metal substrate via a low melting point glass, and at least the lead. A semiconductor package comprising: a cap that holds a frame; and a cap that holds a frame. 2. A metal substrate made of a low thermal expansion alloy coated with a high melting point glass insulating layer on at least the sealing portion and the portion where the inner and outer lead members are scheduled to be disposed, and an inner lead made of an Al or Cu thin film formed on the upper surface of the substrate insulating layer; an external lead consisting of a lead pin that penetrates the metal substrate and is erected through high melting point glass;
1. A semiconductor package comprising a cap that encloses a semiconductor chip fixed to a surface of a metal substrate and seals the metal substrate through a low-melting glass.