JP2525853Y2 - Lead frame - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to a structure of a lead frame, and more particularly to an improvement of a lead frame used for a package for housing a semiconductor element.

(Prior art and its problems) Conventionally, a semiconductor element housing package for housing a semiconductor element, in particular, a semiconductor integrated circuit element, is usually made of an electrically insulating material such as alumina ceramics. The recess for accommodating and the molybdenum (M
o), an insulating base having a metallized metal layer made of a refractory metal powder such as tungsten (W), manganese (Mn) or the like; and a silver braze (metallized metal layer) for electrically connecting a semiconductor element to an external circuit. Kovar (Fe-Ni-Co alloy) or 42Al brazed through a brazing material such as Ag-Cu alloy)
Consists of external lead terminals made of loy (Fe-Ni alloy), etc., and a lid. A semiconductor element is attached and fixed to the bottom of the concave portion of the insulating base, and each electrode of the semiconductor element is bonded to the metallized metal layer. Electrically connected via wires and bonding the lid to the upper surface of the insulating base with a sealing material such as glass or resin to hermetically seal the semiconductor element inside the container consisting of the insulating base and the lid. Thus, a semiconductor device is obtained.

Such a conventional package for housing semiconductor elements, when the external lead terminals are individually brazed to each of the metallized metal layers provided on the insulating base, in order to facilitate the workability of the brazing, When a metal layer with excellent corrosion resistance is deposited on the surface by plating, external force is applied to the external lead terminals to improve the workability of the deposition and to transport the semiconductor element storage package. In order to prevent the external lead terminals from being deformed by the external force, one end of each external lead terminal is commonly connected to the inner periphery of a rectangular ring-shaped frame at a fixed interval, whereby the external lead terminals are connected. Can greatly improve the workability of brazing to each metallized metal layer provided on the insulating substrate and the workability of depositing the corrosion-resistant metal layer, and effectively prevent deformation during transportation. It has become way.

The external lead terminals are formed by forming an ingot of Kovar, 42Alloy or the like into a thin plate by a rolling method and punching it into a predetermined shape by a metal punching method, and a rectangular annular frame to which one end of each external lead terminal is connected. Are also formed at the same time when the external lead terminals are formed.

However, in recent years, semiconductor packages housed in semiconductor packages have become denser and more highly integrated, and the number of external lead terminals used in the packages has become extremely large. Has a line width of about 20
It has become as thin as 0 μm and the line thickness is about 200 μm. Therefore, it is impossible to form an external lead terminal having a small line width by the conventional metal stamping method, so that a lead frame formed by using an etching method capable of fine processing, specifically, both main surfaces of a metal sheet. A mask having a predetermined pattern is applied to the metal sheet, and an etching solution is sprayed from one main surface side of the sheet metal to etch a part of the sheet metal to form a rectangular ring as shown in FIG. A plurality of thin external lead terminals 22 on each side of the inner circumference of the frame 21
Are being used at regular intervals.

However, when the lead frame 23 is formed by etching a thin metal plate, since the space formed at each corner A of the rectangular annular frame 21 is wider than the space formed between the external lead terminals 22, Each corner A of the annular frame 21
In other words, the main surface side of the outer lead terminal 22a located at the outermost side of each side of the rectangular annular frame 21 on which the etchant is sprayed is largely etched by a large amount of the etchant. FIG. 4 (b)
As shown in (1), the line width on the side on which the etching liquid is jetted is narrower than the line thickness. Therefore, when a package for housing a semiconductor element is manufactured using the lead frame 23 and the external lead terminals 22 (22a) brazed to the insulating base of the package are uniformly bent to electrically connect to an external circuit, a square The outer lead terminal 22a located on the outermost side of each side of the annular frame 21 has a laterally asymmetric cross section, and a part of the line width is smaller than the line thickness. Bends in a direction different from that of the external lead terminals 22. As a result, it becomes impossible to bend all the external lead terminals evenly, and all the external lead terminals 22 (22a) are accurately and reliably connected to the external circuit. Induced the disadvantage that you can not.

(Purpose of the invention) The present invention was devised in view of the above-mentioned drawbacks, and its purpose is to make it possible to bend all the external lead terminals evenly and to make all the external lead terminals accurate and reliable to the external circuit. It is an object of the present invention to provide a lead frame which can be connected to a lead frame.

(Means for Solving the Problems) The present invention relates to a lead frame in which one end of a plurality of external lead terminals is connected to each side of the inner periphery of a rectangular annular frame at a fixed interval, and at each corner of the rectangular annular frame. The enlarged portion is provided, and the outer periphery of the enlarged portion is disposed close to the outside of the external lead terminal located at the outermost side of each side of the rectangular annular frame with a spacing of 0.8 to 1.2 times the interval between the external lead terminals. It is characterized by having.

(Example) Next, the present invention will be described in detail based on an example shown in the accompanying drawings.

1 (a) and 1 (b) show an embodiment of a lead frame according to the present invention. A lead frame 1 is composed of a plurality of external lead terminals 2 and a frame 3 having a rectangular ring shape.

The external lead terminal 2 serves to electrically connect the semiconductor element housed in the insulating container of the semiconductor element housing package to an external circuit, and has a line width of about 200 μm and a line thickness of about 150 μm. In addition, one end side is brazed to a metallized metal layer provided on the outer surface of the insulating container via a brazing material such as silver brazing (Ag-Cu alloy).

The plurality of external lead terminals 2 are arranged at regular intervals (for example, 0.
The frame 3 regulates the position of each of the external lead terminals 2, and the workability when brazing one end of the external lead terminals 2 to the metallized metal layer of the insulating container is improved. It has an effect of improving workability when a metal layer having excellent corrosion resistance is deposited on the outer surface of the external lead terminal 2 by plating.

The connection of the external lead terminals 2 to the frame 3 is such that the distance between the adjacent external lead terminals 2 corresponds to the distance between the metallized metal layers provided on the insulating container.

Each of the external lead terminals 2 and the frame 3 is made of a metal such as Kovar (Fe-Ni-Co alloy) or 42Alloy (Fe-Ni alloy). The ingot such as Kovar is processed into a thin plate by a rolling method. The thin metal plate is formed at a time by etching and etching into a predetermined shape.

The lead frame 1 also has an enlarged portion B at each corner of the frame 3 having a rectangular ring shape, and the outer periphery of the enlarged portion B is outside the external lead terminal 2 a located at the outermost side of each side of the frame 3. 0.8 for the distance between each external lead terminal 2
They are arranged close to each other with an interval of 1.2 times.

An enlarged portion B provided at each corner of the rectangular frame 3 is formed by etching a thin metal plate.
Is formed, a large amount of the etching solution is prevented from being sprayed onto the outer surface of the external lead terminal 2a located on the outermost side of each side of the frame 3 so that the etching solution is supplied to all the external lead terminals 2a.
(2a), so that the outer lead terminals 2a located on the outermost sides of the frame 3 do not have a large portion of the outer surface thereof etched, and the other external leads are The shape can be substantially the same as the terminal 2. Therefore, when this external lead terminal 2a is evenly bent together with the other external lead terminals 2, the external lead terminal 2a
Since the shape is substantially the same as that of the other external lead terminals 2, it can be uniformly bent in the same direction as the external lead terminals 2.

The distance (interval) t ₁ from the outer surface of the external lead terminals 2a outer periphery is located on each side outermost frame 3 of ampulla B provided at each corner of the frame 3 forming the rectangular annular each to interval t ₂ between the external lead terminals 2, when it comes to _{1.2t 1 <t 1 <0.8t 2} , the external lead shape of the terminal 2a is not become uniform and the other external lead terminals 2 form, all of the external lead The terminal 2 (2a) cannot be bent in the same direction and evenly. Therefore, the distance (interval) t ₁ from the outer lead terminal 2 a located on the outermost side of each side of the frame 3 to the outer periphery of the enlarged portion B provided on the frame 3 is larger than the interval t ₂ between the external lead terminals 2. , 0.8t ₂ ≦ t ₁ ≦ 1.2t ₂ .

Next, a method for manufacturing a lead frame according to the present invention will be described with reference to FIGS. 2 (a), 2 (b), 2 (c) and 2 (d).

First, as shown in FIG. 2A, a thin metal plate 4 having a thickness of about 150 μm is prepared.

The metal sheet 4 is made of Kovar or 42Alloy, and a predetermined amount of iron, nickel, and cobalt is heated and melted and alloyed to produce an ingot of Kovar or 42Alloy, and the ingot is rolled to a thickness of about 150 μm. It is formed by rolling.

Next, as shown in FIG. 2 (b), an etching mask 5 is applied to both main surfaces of the metal sheet 4.

The etching mask 5 is applied to both main surfaces of the metal thin plate 4 by employing a conventionally known photolithography technique, and the shape of the etching mask 5 is a shape corresponding to the shape of a lead frame to be manufactured.

Next, as shown in FIG. 2C, an etching solution is sprayed from one main surface side of the metal thin plate 4 on which the etching mask 5 is applied, and a portion where the etching mask 5 does not exist, that is, the metal thin plate 4 is exposed. The portion to be etched is etched to form a frame 3 and a number of external lead terminals 2 having one end connected to the frame 3.

In this case, since an enlarged portion B having an enlarged corner portion of the frame 3 is formed outside the external lead terminal 2a located at the outermost portion of the frame 3, the enlarged portion B forms the outermost portion of each side of the frame 3. A large amount of the etching solution is not sprayed on the external lead terminals 2a located at the position (1), and the etching solution is sprayed uniformly on all the external lead terminals 2 (2a). Can be made substantially the same.

Then, after the metal thin plate 4 is etched to form the external lead terminals 2 (2a) and the frame 3,
As shown in FIG. 2D, the etching mask 5 is removed, whereby the lead frame 1 is completed.

Next, a method of manufacturing a semiconductor device housing package using the lead frame of the present invention will be described with reference to the embodiment shown in FIG.

First, an insulating base 6 for housing a semiconductor element as shown in FIG. 3 is prepared.

The insulating base 6 has a plurality of metallized metal layers 7 on its upper surface. The insulating base 6 having the metallized metal layers 7 is formed by laminating a plurality of unfired ceramic sheets having a surface coated with a metal paste by printing. It is formed by firing at a temperature of about 1400 to 1600 ° C. in a reducing atmosphere (in H ₂ —N ₂ gas).

The unsintered ceramic sheet is formed by adding a suitable organic solvent and a solvent to a ceramic raw material powder such as alumina and silica to form a slurry, and forming the slurry into a sheet by a conventionally known doctor blade method. You.

The metal paste is tungsten, molybdenum,
It is prepared by adding and mixing an appropriate organic solvent and a solvent to a high melting point metal powder such as manganese, and is printed and applied to the surface of the unfired ceramic sheet by a conventionally known thick film method such as screen printing.

Next, the insulating base 6 having the metallized metal layer 7 is set in a jig (not shown) made of carbon together with the lead frame 1 shown in FIG. Positioning is performed such that one end of the external lead terminal 2 (2a) is placed via a brazing material 8 such as silver brazing. In this case, one end of each external lead terminal 2 (2a) is connected to the frame 3 and the position is regulated, so that all the external lead terminals 2 (2a) are received on the insulating base 6 by the metallized metal layer. 7 can be aligned at once and easily.

Then, the aligned insulating substrate 6 and the lead frame 1 are passed through a furnace heated to a temperature of about 900 ° C., and the brazing material 8 is heated and melted so that the external lead terminals 2 (2 a) are metallized metal layers. Solder to 7.

Finally, a metal having excellent corrosion resistance, such as nickel or gold, is applied on the outer surface of the external lead terminal 2 (2a) brazed to the metallized metal layer 7 by electrolytic plating, thereby forming a semiconductor device as a product. The package for storage is completed.

In this case, since one end of each of the external lead terminals 2 (2 a) is commonly connected to the frame 3, all the external lead terminals 2 (2 a) need only be connected to the electrode 3 for electrolytic plating. An electric field for plating can be commonly applied to 2a), and the operation of electrolytic plating becomes extremely easy.

In addition, since the completed semiconductor device housing package has one end of the external lead terminal 2 (2a) commonly connected to the frame 3, the external lead terminal 2 (2a) can be used for transporting the semiconductor device housing package. The external lead terminal 2 (2a) is not greatly deformed even if an external force is applied to the external lead terminal. As a result, the external lead terminal 2 (2a) can be connected accurately and securely to a predetermined external circuit. Becomes

(Effects of the Invention) According to the present invention, in a lead frame in which one end of a plurality of external lead terminals is connected to each inner peripheral side of a rectangular annular frame at a fixed interval, an enlarged portion is formed at each corner of the rectangular annular frame. And the outer periphery of the enlarged portion is arranged close to the outside of the external lead terminals located at the outermost sides of each side of the rectangular annular frame with an interval of 0.8 to 1.2 times the interval between the external lead terminals. When a metal thin plate is etched to form a lead frame, all the external lead terminals can be made to have substantially the same shape. Therefore, when all the external lead terminals are uniformly bent to electrically connect to the external circuit, all the external lead terminals can be bent in the same direction and evenly, and all of the external lead terminals are connected to the external circuit. It is possible to connect accurately and reliably.

[Brief description of the drawings]

FIG. 1A is a plan view showing an embodiment of the lead frame according to the present invention, FIG. 1B is an enlarged cross-sectional view of the lead frame shown in FIG. a) (b)
(C) and (d) are enlarged cross-sectional views for each step for explaining the method for manufacturing the lead frame shown in FIGS. 1 (a) and (b).
FIG. 3 is a cross-sectional view for explaining a method of manufacturing a semiconductor element housing package using the lead frame shown in FIGS. 1A and 1B, and FIG. 4A is a plan view of a conventional lead frame. FIG. 4 (b) is an enlarged cross-sectional view of the lead frame shown in FIG. 4 (a) along the line XX. 1 ... lead frame 2, 2a ... external lead terminal 3 ... square ring-shaped frame B ... huge part

Claims (1)

(57) [Scope of request for utility model registration] A metal sheet formed by etching;
A lead frame in which one ends of a plurality of external lead terminals are connected at regular intervals to respective inner peripheral sides of a rectangular annular frame, wherein an enlarged portion is provided at each corner of the rectangular annular frame, and By placing the outer periphery close to the outer lead terminals located on the outermost side of each side of the rectangular annular frame with an interval of 0.8 to 1.2 times the interval between the external lead terminals, the line width of all the external lead terminals can be reduced. A lead frame characterized by being thicker than a line thickness and having a symmetrical cross section.