JPH08148630A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE: To provide a production method for a semiconductor device capable of electrically connecting an internal semiconductor element to an external electrical circuit accurately and reliably. CONSTITUTION: A process for adhering a first metal layer 8 consisting of silver or palladium to the surface of a metalized wiring layer 4 of an insulating substrate 1 and a process of adhering a second plating metal layer 9 consisting of tin-lead on the surface of an external lead terminal 2 are adopted and the metalized wiring layer 4 of the insulating substrate 1 and external lead terminal 2 are contacted together and heated. And a first plated metal layer 8 adhered to the surface of the metalized wiring layer 4 of the insulating substrate 1 and a second plated metal layer 9 adhered to the surface of the external lead terminals 2 are mutually diffused, a tin-leadsilver alloy or a tin-lead-palladium alloy is formed, and the metalized wiring layer 4 and the external lead terminal 2 are jointed together through a tin-lead-silver alloy or a tin-leadpalladium alloy in one of the processes for manufacturing the semiconductor devices.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device used in an information processing device such as a computer.

[0002]

2. Description of the Related Art Conventionally, a semiconductor device used in an information processing device such as a computer is provided with a semiconductor element, a die pad on which the semiconductor element is mounted, and a large number of external leads surrounding the die pad and extending from the vicinity of the die pad at predetermined intervals. A lead frame, which is composed of a terminal and a molding resin that covers a part of the semiconductor element, the die pad and the external lead terminal, and in which the die pad and a large number of external lead terminals are integrally connected to each other through a frame-shaped connecting band. A semiconductor element is mounted and fixed on the upper surface of the die pad of the lead frame, and then each electrode of the semiconductor element and an external lead terminal are electrically connected through a bonding wire, and the semiconductor element, the die pad and the external lead are also connected. It is manufactured by covering a part of the terminal with a mold resin.

The lead frame is made of a metal containing copper as a main component, a metal containing iron as a main component, etc., and a conventionally known punching process or etching process is applied to a thin plate made of a metal containing copper as a main component. It is manufactured by applying metal processing such as.

However, in the conventional lead frame formed by punching or etching, the width of the external lead terminals and the distance between the adjacent external lead terminals are 0.3.
Since it is difficult to make the width extremely narrow, such as mm or less, and when a semiconductor element with a large number of electrodes has been mounted in recent years due to high integration, a large number of external lead terminals should be placed close to the semiconductor element. It cannot be placed. Therefore, the bonding wire that electrically connects each electrode of the semiconductor element and the external lead terminal becomes long, and as a result, the bonding wire is used when the semiconductor element, the die pad and a part of the external lead terminal are covered with the mold resin. When an external force is applied to the bonding wire, the bonding wire is easily deformed by a slight external force, and adjacent bonding wires come into contact with each other to cause an electrical short circuit.

In order to solve the above-mentioned drawbacks, an electrically insulating material such as an aluminum oxide sintered body is provided, and a mounting portion for mounting a semiconductor element is provided on the upper surface, and a large number of metallized wirings are provided from the periphery of the mounting portion to the outer peripheral portion. An insulating substrate in which layers are applied in high density in a fan shape and a lead frame in which one end of a large number of external lead terminals are commonly connected to a frame-shaped connecting band are prepared, and the metallized wiring layer of the insulating substrate is externally provided. The other end of the lead terminal is joined via a brazing material such as silver solder, solder, or gold-tin solder, and then the semiconductor element is mounted and fixed on the mounting portion of the insulating base and each electrode of the semiconductor element is metalized. The wiring layer is electrically connected via a bonding wire, and finally the insulating substrate, the semiconductor element and a part of the external lead terminal are covered with a molding resin. Semiconductor device has been proposed was.

In such a semiconductor device, after covering the insulating substrate, the semiconductor element and a part of the external lead terminal with a molding resin, one end of the external lead terminal is cut and separated from the frame-shaped connecting band, and each external lead terminal is electrically connected. By independently making them independent and connecting each external lead terminal to the external electric circuit, the internal semiconductor element is electrically connected to the external electric circuit.

In the semiconductor device, a large number of metallized wiring layers arranged in a fan shape on the upper surface of the insulating substrate are
Generally, it is formed of a refractory metal powder such as tungsten, molybdenum, or manganese. Since the refractory metal powder such as tungsten or molybdenum has poor wettability with the brazing material, the brazing material is used for the external lead terminal and the metallized wiring layer. In order to firmly bond through the metallized wiring layers, a metal having a good wettability with the brazing material, for example, gold is deposited in advance to a predetermined thickness on the surface of each metallized wiring layer.

[0008]

However, in the semiconductor device described above, when the metallized wiring layer of the insulating substrate and the external lead terminal are joined via silver solder, for example, the aluminum oxide sintered body constituting the insulating substrate is formed. Has a large difference from the coefficient of thermal expansion of the metal mainly composed of copper that constitutes the lead frame, and the melting point of the silver solder that joins the metallized wiring layer of the insulating substrate and the external lead terminal is about Since the temperature is as high as 800 ° C. and the like, when the metallized wiring layer of the insulating substrate and the external lead terminal are joined via the silver brazing material, the difference in thermal expansion between the two becomes large, so that the metallized wiring layer and the external lead terminal are large. Since the positions of the lead frame and the metallized wiring layer are misaligned, it is difficult to join them accurately, and a large thermal stress is generated between the lead frame and the metallized wiring layer. Or break the external lead terminals by thermal stresses, it will be peeled off from the metallized wiring layer, exactly the semiconductor element to the outside, to induce disadvantage and surely not be electrically connected.

When the metallized wiring layer of the insulating base and the external lead terminals are joined via solder, the melting point of the solder is as low as 183 ° C., so that the insulating base, the semiconductor element and a part of the external lead terminals are When coating with mold resin,
Heat for thermosetting the molding resin (usually about 200 ℃)
Is applied, the solder is melted by the heat and the metallized wiring layer and the external lead terminal are disjoined or misaligned, and the internal semiconductor element is also accurately and surely electrically connected to the external electric circuit. Induced the drawback of not being able to.

Further, when the metallized wiring layer of the insulating substrate and the external lead terminal are joined via gold-tin solder,
The gold-tin brazing material has a hard and brittle property, and therefore when the semiconductor element is bonded and fixed to the insulating substrate, or when the electrode of the semiconductor element and the metallized wiring layer are electrically connected via a bonding wire, Alternatively, when an unnecessary external force is applied to the external lead terminal when the insulating substrate, the semiconductor element, and a part of the external lead terminal are covered with the mold resin, the external force causes cracks in the gold-tin brazing material, and the external lead The terminal was peeled off together with the brazing material from the metallized wiring layer, which caused a defect that the internal semiconductor element could not be accurately and surely electrically connected to the external electric circuit.

Furthermore, in order to firmly bond the external lead terminals to the metallized wiring layer deposited on the upper surface of the insulating substrate through the brazing material, gold is deposited on the surface in advance by a plating method. However, since the gold is expensive, the semiconductor device as a product is extremely expensive.

[0012]

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-mentioned conventional drawbacks, and an object thereof is to provide a semiconductor device capable of electrically connecting an internal semiconductor element to an external electric circuit accurately and surely. To provide.

[0013]

According to the present invention, there is provided an insulating base having a mounting portion on which a semiconductor element is mounted in the central portion of an upper surface and a metallized wiring layer extending from the periphery of the mounting portion to an outer peripheral portion, and mounting of the insulating base. A semiconductor element mounted on the metallization part and having electrodes connected to the metallized wiring layer, an external lead terminal joined to the metallized wiring layer via a brazing material, and one of the insulating substrate, the semiconductor element and the external lead terminal. A semiconductor device comprising a mold resin for covering a portion, wherein the metallized wiring layer and the external lead terminal are joined by the following steps (1) to (3).

(1) A step of depositing a first plated metal layer made of silver or palladium on the surface of the metallized wiring layer of the insulating substrate, and (2) a second plated metal layer made of tin-lead on the surface of the external lead terminal. And (3) bringing the metallized wiring layer of the insulating substrate and external lead terminals into contact with each other and heating them to deposit the first plated metal layer and the external lead on the surface of the metallized wiring layer of the insulating substrate. The second plated metal layer deposited on the terminal surface is interdiffused to form a tin-lead-silver alloy or a tin-lead-palladium alloy, and the tin-lead-silver alloy or tin-lead-palladium alloy A step of joining the metallized wiring layer and the external lead terminal.

[0015]

According to the manufacturing method of the present invention, the metallized wiring layer coated with the first plated metal layer made of silver or palladium and the external lead terminal coated with the second plated metal layer made of tin-lead. And heat to make the first plated metal layer deposited on the metallized wiring layer and the second plated metal layer deposited on the surface of the external lead terminal interdiffuse to form a tin-lead-silver alloy or Since the tin-lead-palladium alloy is formed and the metallized wiring layer and the external lead terminal are joined via the tin-lead-silver alloy or the tin-lead-palladium alloy, the metallized wiring layer and the external lead terminal are joined together by the tin-lead alloy. The lead-silver alloy or tin-lead-palladium alloy is formed. It can be joined at a low temperature of about 240 ℃, and as a result, the metallized wiring layer and the external lead terminal are joined. At this time, the difference in the amount of thermal expansion between the two can be made extremely small, so that the two can be joined accurately and firmly, and the brazing material composed of the once solidified tin-lead-silver alloy or tin-lead-palladium alloy is about It will not melt unless heated to 250 ° C or higher, and the brazing material will not melt due to the heat of thermosetting the molding resin. This will ensure that the external lead terminals are securely and firmly bonded to the metallized wiring layer. Therefore, the internal semiconductor element can be electrically connected to the external electric circuit accurately and surely.

Further, according to the manufacturing method of the present invention, since no expensive gold is used for joining the metallized wiring layer of the insulating substrate and the external lead terminal, the semiconductor device as a product is made extremely inexpensive. You can also

[0017]

The present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a semiconductor device manufactured by the manufacturing method of the present invention, in which 1 is an insulating substrate, 2 is an external lead terminal, and 3 is a semiconductor element.

The insulating substrate 1 has a mounting portion 1a for mounting a semiconductor element in the center of the upper surface thereof.
The semiconductor element 3 is bonded and fixed to a by an adhesive such as resin, glass, or brazing material.

The insulating substrate 1 is an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body,
When it is made of an electrically insulating material such as a silicon carbide sintered body or a glass ceramics sintered body, for example, when it is made of an aluminum oxide sintered body, it is suitable as a raw material powder of aluminum oxide, silicon oxide, calcium oxide, magnesium oxide or the like. A binder and a solvent are added and mixed to form a slurry, and a ceramic green sheet is obtained by forming it into a sheet by adopting a conventionally known doctor blade method.After that, the ceramic green sheet is punched by a method such as a punching method. It is manufactured by punching into an appropriate shape, laminating a plurality of sheets as necessary, and finally firing the ceramic green sheet in a reducing atmosphere at a temperature of about 1600 ° C.

Further, the insulating base 1 is formed with a large number of metallized wiring layers 4 which are spread in a fan shape from the periphery of the mounting portion 1a where the semiconductor element 3 is mounted on the upper surface central portion to the outer peripheral portion. External lead terminals 2 which are electrically connected to respective electrodes of the semiconductor element 3 via the bonding wires 5 in the peripheral portion of the mounting portion 1a of the wiring layer 4 and connected to an external electric circuit in the outer peripheral portion of the insulating substrate 1. Are joined via the brazing material 6.

The metallized wiring layer 4 is made of a refractory metal powder such as tungsten, molybdenum, or manganese, and a metal paste obtained by adding and mixing an appropriate binder and solvent to the refractory metal powder such as tungsten is used as the insulating substrate. The ceramic green sheet to be No. 1 is formed into a fan shape from the upper surface around the mounting portion 1a of the insulating substrate 1 to the upper surface of the outer peripheral portion of the insulating substrate 1 by applying a thick film method such as a well-known screen printing method to print and apply the pattern in advance. It is formed so as to spread over.

Since the metallized wiring layer 4 is printed and applied by the screen printing method, the line width and the space between the adjacent metalized wiring layers 4 can be made as narrow as about 0.05 mm or less. , A large number of metallized wiring layers 4 are arranged in the vicinity of the semiconductor element 3
A short bonding wire 5 between the metallized wiring layer 4 and
It is possible to electrically connect with each other, and it is possible to effectively prevent an electrical short circuit between the adjacent bonding wires 5.

The external lead terminal 2 joined to the metallized wiring layer 4 via the brazing material 6 serves to connect the semiconductor element 3 housed therein to an external electric circuit, and the external lead terminal 2 is externally connected. By connecting to the wiring conductor of the electric circuit board, the semiconductor element 3 is electrically connected to the external electric circuit via the metallized wiring layer 4 and the external lead terminal 2.

The external lead terminals 2 are made of a metal such as a copper-based alloy containing copper as a main component or an iron-based alloy containing iron as a main component. For example, an ingot of a copper-based alloy is formed by a conventionally known rolling method. Then, it is formed into a plate shape having a predetermined thickness, and is subjected to etching processing or punching processing to have a predetermined shape.

When the external lead terminal 2 is formed of a metal containing copper as a main component, the metal containing copper as a main component is
The heat conductivity is excellent, and the heat generated during the operation of the semiconductor element 3 can be satisfactorily dissipated into the external atmosphere through the external lead terminals 2, so that the semiconductor element 3 can always be operated at a low temperature and stably operated. Therefore, the external lead terminals 3 are preferably formed of a metal containing copper as a main component.

The brazing material 6 for joining the external lead terminal 2 to the metallized wiring layer 4 is made of a tin-lead-silver alloy or a tin-lead-palladium alloy, and the external lead terminal 4 is firmly bonded to the metallized wiring layer. Performs the action of joining.

Since the tin-lead-silver alloy or the tin-lead-palladium alloy forming the brazing material 6 has high toughness, the external lead terminal 2 is brazed even if an unnecessary external force is applied to the external lead terminal 2. 6 does not easily peel from the metallized wiring layer 4 and has a melting point of about 25 each.
Since the temperature is 0 ° C. or higher, the brazing material 6 is not melted by the heat when the mold resin described later is thermally cured, and the external lead terminal 2 can be reliably and firmly bonded to the metallized wiring layer 4.

On the other hand, the insulating substrate 1 and the semiconductor element 3 are
Also, a part of the external lead terminal 2 is covered with a mold resin 7 such as an epoxy resin, whereby the semiconductor element 3 is hermetically sealed inside.

In order to cover the insulating substrate, the semiconductor element and a part of the external lead terminal with the molding resin 7, the insulating substrate 1 to which the semiconductor element 3 and the external lead terminal 2 are bonded is placed in a predetermined molding die. At the same time, a mold resin such as an epoxy resin is injected into the mold, and then the injected resin is thermally cured by applying a temperature of about 200 ° C. and a pressure of 100 kgf / mm 2.

Next, in the above-mentioned semiconductor device, a method for joining the external lead terminal 2 to the metallized wiring layer 4 of the insulating substrate 1 through the brazing material 6 made of a tin-lead-silver alloy or a tin-lead-palladium alloy is illustrated. A description will be given based on 2 (a) to (d). First, as shown in FIG. 2A, an insulating substrate 1 having a metallized wiring layer 4 and external lead terminals 2 are prepared.

Next, as shown in FIG. 2B, a first plated metal layer 8 made of silver or palladium is applied to the outer surface of the metallized wiring layer 4 of the insulating substrate 1 to a thickness of 0.05 to 2.0 μm, At the same time, a second plated metal layer 9 made of tin-lead is sequentially deposited on the surface of the external lead terminal 2 to a thickness of 3.0 to 100 μm.

Next, as shown in FIG. 2 (c), one end of the external lead terminal 2 is placed on the metallized wiring layer 4 of the insulating substrate 1 and these are heated to a temperature of about 240 ° C. to form a metallized wiring layer. The first plated metal layer 8 made of silver or palladium deposited on the No. 4 and the second plated metal layer 9 made of tin-lead deposited on the external lead terminal 2 are interdiffused to form a tin-lead-silver alloy or If a brazing material 6 made of a tin-lead-palladium alloy is formed, and the metallized wiring layer 4 of the insulating base 1 and the external lead terminal 2 are joined by the brazing material 6, as shown in FIG. Metallized wiring layer 4
A semiconductor device in which the external lead terminal 2 is joined to the above is completed. In this case, since the metallized wiring layer 4 of the insulating base 1 and the external lead terminal 2 can be bonded at a low temperature of about 240 ° C., when the metallized wiring layer 4 and the external lead terminal 2 are bonded, The difference in the amount of thermal expansion from the external lead terminal 2 is extremely small, so that the positions of the metallized wiring layer 4 and the external lead terminal 2 are not displaced, and the metallized wiring layer 4 and the external lead terminal 2 are not separated from each other. No large thermal stress is generated. Further, the brazing material 6 made of the tin-lead-silver alloy or the tin-lead-palladium alloy once cooled and solidified does not remelt unless heated to a temperature of about 250 ° C. or more, and the insulating substrate 1 and the semiconductor element 3 are not melted. Also, the external lead terminals 2 are not melted by the heat when they are covered with the molding resin 7. Therefore, according to the manufacturing method of the present invention, the external lead terminal 2 can be joined to the metallized wiring layer 4 of the insulating substrate 1 accurately and firmly.

The present invention is not limited to the above-mentioned embodiments, and various modifications can be made without departing from the gist of the present invention.

[0035]

According to the manufacturing method of the present invention, the metallized wiring layer having the first plated metal layer made of silver or palladium deposited thereon and the second plated metal layer made of tin-lead coated on the outside The lead terminals are brought into contact with each other and heated so that the first plated metal layer deposited on the metallized wiring layer and the second plated metal layer deposited on the surface of the external lead terminals are mutually diffused to form tin-lead-silver. An alloy or a tin-lead-palladium alloy is formed, and the metallized wiring layer and the external lead terminal are joined together through the tin-lead-silver alloy or the tin-lead-palladium alloy. The tin-lead-silver alloy or tin-lead-palladium alloy is formed. It can be joined at a low temperature of about 240 ℃, and as a result, the metallized wiring layer and the external lead terminal are joined. When these are made, the difference in the amount of thermal expansion between them can be made extremely small and both can be joined accurately and firmly, and the brazing material composed of the once solidified tin-lead-silver alloy or tin-lead-palladium alloy is about
It will not melt unless heated to 250 ° C or higher, and the brazing material will not melt due to the heat of thermosetting the molding resin. This will ensure that the external lead terminals are securely and firmly bonded to the metallized wiring layer. Therefore, the internal semiconductor element can be electrically connected to the external electric circuit accurately and surely.

Further, according to the manufacturing method of the present invention, since no expensive gold is used for joining the metallized wiring layer of the insulating substrate and the external lead terminal, the semiconductor device as a product is made extremely inexpensive. You can also

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a semiconductor device of the present invention.

2A to 2D are cross-sectional views for each step for explaining a method of manufacturing the semiconductor device shown in FIG.

[Explanation of symbols]

 1 ... Insulating substrate 1a ... Mounting part 2 ... External lead terminal 3 ... Semiconductor element 4 ... Metallized wiring layer 5 ... Bonding wire 6 ... Brazing material 7 ... Mold resin 8 ... 1st plating metal layer 9 ... 2nd plating metal layer

Claims (1)

[Claims] 1. An insulating base having a mounting portion on which a semiconductor element is mounted in a central portion of an upper surface and a metallized wiring layer extending from the periphery of the mounting portion to an outer peripheral portion, and an electrode mounted on the mounting portion of the insulating base and having electrodes as described above. From a semiconductor element connected to the metallized wiring layer, an external lead terminal joined to the metallized wiring layer via a brazing material, and a molding resin that covers the insulating substrate, the semiconductor element and a part of the external lead terminal. A method of manufacturing a semiconductor device, wherein the metallized wiring layer and the external lead terminal are joined by the following steps (1) to (3). (1) A step of depositing a first plated metal layer made of silver or palladium on the surface of the metallized wiring layer of the insulating substrate, and (2) a second step made of tin-lead on the surface of the external lead terminal.
A step of depositing a plated metal layer, and (3) a first plated metal layer deposited on the surface of the metallized wiring layer of the insulating substrate by bringing the metallized wiring layer of the insulating substrate into contact with an external lead terminal and heating. And the second plated metal layer deposited on the surface of the external lead terminal are mutually diffused to form a tin-lead-silver alloy or tin-lead-palladium alloy, and the tin-lead-silver alloy or tin-lead-palladium alloy. A step of joining the metallized wiring layer and the external lead terminal via the.