JPH08191123A - Manufacture of lead frame - Google Patents

Abstract

PURPOSE: To provide a method of manufacturing a lead frame, which can realize high reliability of a package, in the lead frame, which is formed by bonding together an inner lead part and an outer lead part, which are respectively formed by different methods, and is used for mounting a semiconductor element. CONSTITUTION: An inner lead frame 1 obtained in a process in which inner leads 3 are formed on a substrate 9 by an additive method and after that, these inner leads 3 are secured to the substrate with an insulator 10, such as resin or bonding agent, and the insulator 10 is separated from the substrate 9 along with the inner leads 3, is bonded to an outer lead frame 2 formed by a method different from the process, such as a stamping method or an etching method, and a narrow-pitch lead frame is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a lead frame of a semiconductor device which can realize a narrow pitch and high reliability.

[0002]

2. Description of the Related Art Conventionally, new forms have been developed one after another in order to meet the demands of electronic devices for miniaturization, weight reduction, high speed, and high functionality of semiconductor packages, and the types of semiconductor packages are increasing. As logic semiconductors such as CPUs and ASICs become more sophisticated, more input / output pins are required.
Therefore, if the package size is the same, it is inevitable that the lead pitch is narrowed. In the case of memory semiconductor products, the focus of development is on the miniaturization and thinning of packages, and it is low in packaging high-capacity semiconductor chips at high density and in the use of logic semiconductors for consumer products. There is an increasing demand for smaller size and thinner products that are price-based.

The limitation of the leadframe package to other pins is restricted by the processing limit of the leadframe. Conventionally, from the frame plate material to the lead frame, depending on the manufacturing method, a stamping frame in which a metal plate such as copper or 42 alloy is mechanically punched from one side and a pattern punching hole from both sides by a chemical etching method It is roughly divided into an etching frame, and an island portion for mounting a semiconductor element, an inner lead portion for connecting to the semiconductor element with a bonding wire, and an outer lead portion for mounting on a wiring board are collectively manufactured.

FIG. 3A is a sectional view of a conventional stamping frame, and FIG. 3B is a sectional view of a conventional etching frame. The stamping frame has a sufficient lead width for wire bonding and is cheaper than the etching frame in mass production. On the other hand, if there is a possibility that the shape of the etching frame will be changed by trial manufacture and evaluation, the frame shape can be changed relatively easily by changing the mask, and the delivery time can be shortened. Therefore, the cost can be reduced. In addition, the etching frame is superior to the stamping frame in terms of microfabrication of the multi-pin frame, and currently the plate thickness is 0.15 mm.
With a stamping frame of about 200 pins, 3
It is possible to manufacture with about 50 pins. In addition, the TAB (T
Ape Automated Bonding) tape is available, but the cost is high due to the polyimide tape used as the base material.

At present, the above-mentioned manufacturing method is in the mainstream, but there is another manufacturing method called an additive method in which a frame is formed by depositing and depositing a required metal in a frame pattern shape by plating. 4 (a) (b)
(C) (d) (e) (f) (g) is a manufacturing process schematic diagram of the lead frame by the conventional etching method. In the etching method, first, a resist is applied to the front and back surfaces of a metal material such as copper or 42 alloy (FIGS. 4A and 4B). This is masked with a mask formed in a lead frame pattern, and is subjected to baking exposure and development (FIGS. 4 (c) (d) (e)). The resist in the unmasked portion remains undissolved in the developing solution and is immersed in an etching solution to etch the portion not covered with the resist from both sides (FIG. 4 (f)). Finally, the resist is peeled off to obtain a desired lead frame (FIG. 4 (g)).

5 (a) (b) (c) (d) (e)
(F) (g) (h) is a manufacturing process schematic diagram of the lead frame by the conventional additive method. In the additive method, a resist is applied to one surface of a substrate which is a plated substrate (FIGS. 5A and 5B), and masked with a mask formed in a lead frame pattern as in the etching method (FIG. 5C). Baking exposure and development processing are performed (Fig. 5).
(D) (e)). Then, the substrate portion not covered with the resist is plated in a metal plating solution such as copper and nickel (FIG. 5 (f)). Finally, the resist is peeled off (FIG. 5 (g)) and the frame is peeled off from the substrate to obtain a lead frame (FIG. 5).
(H)). As shown in FIG.
As can be seen from the cross-sectional shape of (b), there is a drawback that the wire bonding surface becomes narrower. On the other hand, in the additive method, the lead cross-sectional shape depends on the resist, and when manufacturing the inner lead frame, a more stable bonding area is provided. There is an advantage that can be secured.

With the increase in the number of lead frames in recent years,
It is desired to make the frame thinner in the manufacturing process of the frame, but this makes it difficult to secure the mechanical strength. Therefore, the inner lead part with a narrow lead pitch and the lead pitch with a relatively wide lead pitch are used for lead forming in the assembly. The outer lead portion that requires sufficient lead rigidity is manufactured by another method, and the two are joined by thermocompression bonding or the like to achieve a narrow pitch.

A description will be given below of a bonded lead frame in which the inner lead portion is formed by the additive method and the outer lead portion is manufactured by another method such as stamping and etching.

FIGS. 6A, 6B, 6C and 6D are schematic sectional views showing the manufacturing process of a conventional bonded lead frame. The manufacturing process will be described below. First, FIG. 6A shows the inner lead frame 1 manufactured on the substrate by the additive method in the process shown in FIG. Next, as shown in FIG. 6B, taping is performed on the inner lead frame 1. In the figure, 3 is an inner lead, which is an insulator such as a polyimide tape 6 and the like.
Is fixed. 5 is an island. A force is applied to one end of the inner lead frame 1 from the outside to separate the inner lead frame 1 to obtain a state as shown in FIG. Next, the inner lead frame 1 which is manufactured by stamping or etching, is aligned with the outer lead frame 2 on which the outer leads 4 are formed, and is surface-treated in advance by silver plating or the like as shown in FIG. 6D. And each lead joint portion of the outer lead frame 2 are joined by thermocompression bonding or the like to form a normal lead frame shape.

Further, the power consumption of the LSI has become high due to the high speed and high integration of the LSI, and the amount of heat generated has been increasing, so that high heat dissipation of the package is required. Therefore, the above-mentioned bonded lead frame is dealt with by forming the heat dissipation plate. 7 (a) (b)
(C) and (d) show schematic cross-sectional views of manufacturing steps of a conventional joined lead frame with a heat sink. The manufacturing process will be described below. First, FIG. 7A shows the inner lead frame 1 manufactured on the substrate by the additive method in the process shown in FIG. Next, as shown in FIG. 7B, the heat sink 11 is attached to the inner lead frame 1 via an insulator such as a polyimide tape 6 having an adhesive formed on both sides, and the inner lead 3 is fixed.
A force is applied to one end of the inner lead frame 1 from the outside to separate the inner lead frame 1, resulting in the state shown in FIG. Next, the inner lead frame 1 which is manufactured by stamping or etching, is aligned with the outer lead frame 2 on which the outer leads 4 are formed, and is surface-treated in advance by silver plating or the like as shown in FIG. 7D. And the lead joint portions of the outer lead frame 2 are joined by thermocompression bonding or the like to form a lead frame with a heat sink.

[0011]

However, in the lead frame of the joint portion produced by the conventional additive method as described above, when the inner lead frame produced by the additive plating is peeled from the substrate, the Since the inner lead frame thickness is thin against the force, the strength is weak, and lead deformation occurs after peeling, which causes misalignment during bonding, lead short circuit failure, and wire bonding failure. As described above, when the inner lead portion is formed by the conventional additive method, deformation is likely to occur in the peeling step and the handling in the subsequent steps, so that there is a problem that quality reliability is deteriorated.

Therefore, an object of the present invention is to solve the above-mentioned conventional problems and to provide a method of manufacturing a high quality lead frame having a narrow pitch and a large number of pins.

[0013]

In order to achieve the above object, in the present invention, an inner lead is formed on a substrate by additive plating, and the inner lead portion is fixed with an insulating material such as resin or adhesive. After doing
The inner lead portion is peeled off from the substrate together with this insulator to produce an inner lead frame, and this inner lead frame is joined to an outer lead frame separately produced to produce a narrow pitch lead frame. Alternatively, the inner leads are made on the substrate by additive plating, and after attaching the heat sink through the insulator such as polyimide tape, the inner lead portion with the heat sink is fixed with an insulator such as resin or adhesive. After that, the inner lead part with a heat sink is peeled off from the substrate together with this insulator to produce an inner lead frame with a heat sink, and this inner lead frame with a heat sink is joined to an outer lead frame that is separately manufactured to reduce the space. This is to produce a lead frame with high heat dissipation at a pitch.

[0014]

According to the present invention, since the lead is fixed by the insulator before the inner lead frame is peeled from the substrate, the lead is not deformed by an external force at the time of peeling. Therefore, the position shift during joining,
A narrow-pitch lead frame that provides a highly reliable semiconductor device in which lead short-circuit defects and wire bonding defects are prevented is produced.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. 1 (a) (b) (c) (d) (e)
FIG. 3 is a schematic cross-sectional view of the manufacturing process of the bonding lead frame and the semiconductor device according to the first embodiment of the present invention. The same components as those in the conventional example are designated by the same reference numerals, 1 is an inner lead frame provided with an inner lead 3, and 2 is an inner lead frame.
Is the outer lead 4 which is a mounting part on the printed wiring board
An outer lead frame provided with a bonding wire 8 for connecting the semiconductor element 7 and the inner lead 3.
Is a substrate for additive plating, and 10 is an insulator.

Next, the manufacturing method thereof will be described. The inner leads 3 produced by additive plating are produced on the substrate 9 in the process as shown in FIG. 5 (see FIG. 1).
(A)). After fixing the inner leads 3 with an insulator 10 such as a resin or an adhesive (FIG. 1A), the inner leads 3 are separated from the substrate 9 together with the insulator 10 to obtain the inner lead frame 1. (FIG. 1 (c)). The inner lead frame 1 and the outer lead frame 2 produced by stamping or etching are subjected to surface treatment such as silver plating in advance, and the both are aligned and joined by thermocompression bonding or the like. It has a frame shape (FIG. 1 (d)).
Then, the semiconductor element 7 is mounted on the island 5, and the inner lead 3 is connected to the bonding wire 8 with the semiconductor element 7 (FIG. 1E).

As described above, according to the first embodiment, even if the inner lead frame becomes thin due to the narrower pitch and the larger number of pins and the strength becomes insufficient, the inner lead frame is fixed with an insulator before the peeling process from the substrate. By doing so, it is possible to manufacture a narrow-pitch lead frame that prevents misalignment at the time of joining, lead short circuit failure, wire bonding failure, and the like, and provides a highly reliable semiconductor device.

Next, a second embodiment of the invention will be described.
2 (a), (b), (c), (d), (e), and (f) are schematic cross-sectional views of manufacturing steps of the bonded lead frame and the semiconductor device in the second embodiment of the present invention. 1 is inner lead 3
2 is an inner lead frame provided with an outer lead frame 4 having outer leads 4 which are to be mounted on a printed wiring board, and 8 is a semiconductor element 7 and an inner lead 3.
Is a bonding wire for connecting the substrates, 9 is a substrate for performing additive plating, 10 is an insulator, and 11 is a heat sink.

Next, the manufacturing method will be described. The inner lead frame 1 manufactured by additive plating is manufactured on the substrate 9 in the process as shown in FIG. 5 (FIG. 2A). On the other hand, after the heat dissipation plate 11 made of copper, aluminum or the like is adhered via an insulating material such as the polyimide tape 6 (FIG. 2 (e)), the inner lead 3 together with the heat dissipation plate 11 is insulated with resin or adhesive. The inner lead frame 1 is obtained by fixing the inner lead 3 and the heat dissipation plate 11 together with the insulator 10 from the substrate 9 (FIG. 2 (c)) (FIG. 2 (d)). The inner lead frame 1 and the outer lead frame 2 produced by stamping or etching are subjected to surface treatment such as silver plating in advance, and the both are aligned and joined by thermocompression bonding to radiate heat. It becomes a lead frame shape with a plate (Fig. 2 (e)). Then, the semiconductor element 7 is mounted and the inner lead 3 and the semiconductor element 7 are connected by the bonding wire 8 (see FIG. 2).
(F)).

As described above, according to the second embodiment, the inner lead frame becomes thinner due to the narrower pitch and the larger number of pins, and the inner lead frame with the heat sink is separated from the substrate even if the strength is insufficient. By fixing with an insulator before the process, it is possible to prevent misalignment at the time of joining, lead short circuit failure, wire bonding failure, etc., and by installing a heat sink, heat dissipation during semiconductor device operation is improved and high. A narrow pitch lead frame is produced that provides a reliable semiconductor device.

[0021]

As described above, according to the present invention, even if the lead frame has a narrow pitch and a large number of pins, it is possible to provide a highly reliable semiconductor device which does not cause lead deformation due to an external force when the frame is peeled off. It is possible to manufacture a narrow-pitch lead frame that can be realized.

[Brief description of drawings]

FIG. 1A is a schematic sectional view of a manufacturing process of a bonding lead frame and a semiconductor device according to a first embodiment of the present invention. FIG. 1B is a schematic sectional view of manufacturing processes of a bonding lead frame and a semiconductor device according to a first embodiment of the present invention. (C) Schematic cross-sectional view of the manufacturing process of the bonding lead frame and the semiconductor device according to the first embodiment of the present invention (d) Schematic cross-sectional view of the manufacturing process of the bonding lead frame and the semiconductor device according to the first embodiment of the present invention (e) Schematic cross-sectional view of the manufacturing process of the bonding lead frame and the semiconductor device in the first embodiment of the invention.

FIG. 2 (a) is a schematic cross-sectional view of a bonded lead frame and a semiconductor device in the second embodiment of the present invention, and FIG. 2 (b) is a schematic cross-sectional view of a bonded lead frame and a semiconductor device in the second embodiment of the present invention. (C) Schematic cross-sectional view of the manufacturing process of the bonding lead frame and the semiconductor device according to the second embodiment of the present invention (d) Schematic cross-sectional view of the manufacturing process of the bonding lead frame and the semiconductor device according to the second embodiment of the present invention (e) Book Manufacturing process cross-sectional schematic view of bonded lead frame and semiconductor device in second embodiment of invention (f) Manufacturing process cross-sectional schematic view of bonded lead frame and semiconductor device in second embodiment of the present invention

3A is a sectional view of a conventional stamping frame. FIG. 3B is a sectional view of a conventional etching frame.

4A is a schematic diagram of a lead frame manufacturing process by a conventional etching method. FIG. 4B is a schematic diagram of a lead frame manufacturing process by a conventional etching method. FIG. 4C is a schematic manufacturing process of a lead frame by a conventional etching method. d) Schematic drawing of lead frame manufacturing process by conventional etching method (e) Schematic drawing of manufacturing process of lead frame by conventional etching method (f) Schematic drawing of manufacturing process of lead frame by conventional etching method (g) Conventional etching Schematic drawing of lead frame manufacturing process

FIG. 5A is a schematic view of a lead frame manufacturing process by a conventional additive method. FIG. 5B is a schematic view of a lead frame manufacturing process by a conventional additive method. FIG. 5C is a schematic view of a lead frame manufacturing process by a conventional additive method. d) Schematic diagram of lead frame manufacturing process by conventional additive method (e) Schematic diagram of lead frame manufacturing process by conventional additive method (f) Schematic diagram of lead frame manufacturing process by conventional additive method (g) Conventional additive (H) Schematic drawing of lead frame manufacturing process by conventional additive method

6A is a schematic sectional view of a manufacturing process of a conventional bonded lead frame, FIG. 6B is a schematic sectional view of a manufacturing process of a conventional bonded lead frame, and FIG. 6C is a schematic sectional view of a manufacturing process of a conventional bonded lead frame. Manufacturing process cross-sectional schematic diagram of the joining lead frame

FIG. 7A is a schematic sectional view of a manufacturing process of a conventional bonding lead frame with a heat dissipation plate, and FIG. 7B is a schematic sectional view of manufacturing process of a conventional bonding lead frame with a heat dissipation plate. Manufacturing process cross-sectional schematic diagram (d) Manufacturing process cross-sectional schematic diagram of a conventional bonded lead frame with a heat sink

[Explanation of symbols]

 1 Inner lead frame 2 Outer lead frame 3 Inner lead 4 Outer lead 5 Island 6 Polyimide tape 7 Semiconductor element 8 Bonding wire 9 Substrate 10 Insulator 11 Heat sink

Claims (2)

[Claims] 1. A lead frame for joining the inner lead portion and the outer lead portion by producing an inner lead portion having a narrow lead pitch by additive plating and producing an outer lead portion having a relatively wide lead pitch by stamping or etching. That is, the inner lead frame is produced by additively plating the inner lead pattern on the substrate, and after fixing the inner lead portion with an insulating material such as resin or adhesive, the inner lead pattern is formed together with this insulating material. A method for manufacturing a lead frame, which is manufactured by peeling off from a substrate and bonding the inner lead frame and each lead of an outer lead frame separately manufactured. 2. An inner lead pattern is formed by additive plating, a heat sink is attached through an insulator such as a polyimide tape, and then fixed by an insulator such as a resin or an adhesive. Item 1. A method for manufacturing a lead frame according to Item 1.