JP2632464B2 - Lead frame manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a lead frame, and more particularly to a method for manufacturing a lead frame using etching.

[0002]

2. Description of the Related Art A lead frame used for mounting a semiconductor device such as an IC or LSI is formed by molding a strip made of a metal material such as an iron or copper material into a desired pattern. You.

Conventionally, this pattern forming method is roughly classified into press working and etching. Among these methods, the etching method involves forming a resist pattern on both front and back surfaces of a lead frame material, and etching the lead frame material from both front and back surfaces by immersion in an etchant to form a lead frame pattern. . This method has a feature that it is easy to change the design in addition to a feature that it is easy to miniaturize as compared with press working, but has a drawback that productivity is low.

Further, since etching is performed from both the front and back sides,
As shown in FIG. 6, the etched cross section has a shape protruding at an intermediate portion of the depth, and there is a risk of short-circuiting between leads as miniaturization proceeds. Furthermore, a resist pattern must be formed on both front and back surfaces, a photoresist is applied on both front and back surfaces, and a resist pattern is formed by photolithography. Also, problems such as a decrease in pattern accuracy have become serious problems in further miniaturization.

[0005]

As described above, the conventional processing of the shape of the lead frame by etching involves problems such as poor productivity and a bad cross-sectional shape. was there.

The present invention has been made in view of the above circumstances, and has as its object to form a highly accurate lead frame with good productivity.

[0007]

Therefore, in the method for manufacturing a lead frame according to the present invention, first and second metal materials are adhered to both sides of an etching-resistant plate-like body, and the plate-like body is formed. First and second resist patterns are formed on the surface of the first or second metal material, respectively, and etching is performed using these resist patterns as masks to form desired lead frame patterns including inner leads and outer leads, respectively. After that, the first and second metal materials are peeled off from the plate-like body, so that the first and second metal materials are separated.
Are formed at the same time.

[0008] Desirably, the first and second metal materials are materials having different plate thicknesses. Desirably, the first and second metal materials are made of different materials.

Preferably, the first and second resist patterns are different from each other.

Preferably, prior to the peeling step, the first
In addition, an insulating film is attached to a desired region of the inner lead of the second metal material.

[0011]

According to the method of the present invention, first and second metal members are adhered to both sides of an etching-resistant plate, and the first and second metal members are respectively attached to the surfaces of the first and second metal members. Since the first and second resist patterns are formed and these resist patterns are used as a mask to perform etching to form a lead frame pattern, different types of lead frames can be simultaneously formed independently on the front and back. Thus, it is possible to cope with the diversification of small lots. In addition, since a resist that should be formed on the back surface is also bonded and etched back-to-back with an etching-resistant plate-like body, productivity is improved.

Further, since the first or second metal material is patterned by using the photo-etching method, it is possible to obtain a very high-precision fine pattern.

Since the first and second metal materials are supported by each other via the plate-like body, each metal material itself has a very high mechanical strength even if it is thin. Can be obtained.

As described above, even in a lead frame in which the lead width of the inner lead is small and sufficient strength cannot be obtained, it is possible to obtain the lead frame while maintaining the mutual positional relationship.

Further, if an insulating substance is fixed to each surface before the plate is peeled off after the pattern is formed, a high degree of pattern accuracy can be maintained. In this case, the adhesive for fixing the insulating substance on the surface and the adhesive for fixing the plate-shaped body are different substances, and the adhesive for fixing the insulating substance does not peel when the plate-shaped body is peeled off. You need to do that. By doing so, since the rubbing is performed without any twisting or distortion, there is no thermal distortion, the strength is increased, and the inner lead does not deform during bonding.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a view showing a manufacturing process of a lead frame according to an embodiment of the present invention.

In this method, the first and second layers are sandwiched on both sides of a polyimide film which is an etching-resistant plate.
And a separate resist pattern is formed on the surface of the first or second metal material of the plate-like body, etching is performed using these resist patterns as masks, and the front and back sides are independently read simultaneously. It is characterized by forming a frame pattern.

First, as shown in FIG. 1 (a), a 0.05 mm thick polyimide film 2 is interposed between first and second metal bodies 1a and 1b each made of a nickel strip material having a thickness of 0.08 mm. Are bonded together via an adhesive to form a bonded body.

Then, as shown in FIG. 1B, photoresists 3a and 3b are applied on both front and back surfaces.

Then, as shown in a perspective view in FIG. 2, a resist 3 on the surface of the first and second metal bodies 1a and 1b on the front and back surfaces of the joined body 1 is formed by photoetching.
a, 3b are exposed through the mask patterns 4a, 4b,
Develop to form resist patterns 3a and 3b (FIG. 1)
(c)).

As shown in FIG. 1 (d), the resist pattern thus patterned is used as a mask for immersion in an etching solution to perform shape processing.

Finally, as shown in FIG. 1E, the resist pattern is peeled off and the polyimide film 2 is removed.
And the first and second lead frames R1 and R2 can be obtained. FIG. 3 is a plan view of the first and second lead frames R1 and R2. The pattern of the first lead frame has a pattern shape similar to that of a normal lead frame, and a plurality of patterns formed around the central semiconductor chip mounting region 11 so that the tips thereof face each other. A tie bar 13 is formed between the inner lead 12 and the outer lead 14 connected to the inner lead 12 and extending outward.
Some have a shape connected by. Here, 15 and 16 are frame bodies. On the other hand, the second lead frame pattern has a shape obtained by removing the tie bar 13 from the first lead frame pattern.

In this way, different types of lead frames are simultaneously formed.

Further, in this lead frame, the lead formed by the first metal body pattern on the surface is supported and fixed over a wide range by the pattern of the insulator and the second metal body 1b, so that no deformation occurs. .

Furthermore, productivity is improved because a resist that must be formed on the back surface is also bonded back to back with an etching-resistant polyimide film interposed therebetween and etched.

Then, the first film is interposed via a polyimide film.
Since the second metal material and the second metal material are supported by each other, the mechanical strength is extremely high even if each metal material is thin, and a high-precision pattern can be obtained even when a pattern is formed.

As described above, even in a lead frame in which the lead width of the inner lead is narrow and sufficient strength cannot be obtained, it is possible to obtain the lead frame while maintaining the mutual positional relationship.

In the above embodiment, the first and second metal members are made of the same material and have the same plate thickness. However, the first and second metal members may be made of different materials or plate thicknesses. For example, in the case where the material is different, if the etching rate is different, the mask pattern can be formed to have the same pattern on the front and back sides even if the mask pattern is different. In the case where the plate thicknesses are different, as shown in an example in FIG. 4, if the thickness is smaller, the etching is continued even after the end point of the etching has passed, the side etch amount is increased, and the pattern size is reduced. By utilizing this, it is also possible to adjust the pattern size.

Next, a second embodiment of the present invention will be described.

This embodiment is characterized in that an insulating tape is attached to the inner lead surface of each lead frame before the polyimide film is peeled off after the pattern is formed, so that the inner leads are fixed. .

That is, up to the etching step, FIG.
5 (a) (FIG. 1 (d)), the resist patterns 3a and 3b are first peeled off after completion of the etching as shown in FIG. 5 (a) (FIG. 1 (d)). (FIG. 5B).

Thereafter, as shown in FIG. 5C, a polyimide tape 5 is attached so as to connect a part of the inner leads of the first and second lead frames.

Thereafter, as shown in FIG. 5D, the polyimide film 2 fixing the space between the first and second lead frames is peeled off, and the first and second lead frames are completed. In this step, the adhesive for fixing the polyimide tape 5 on the surface and the adhesive for fixing the polyimide film 2 fixing between the first and second lead frames are made of different materials, It is necessary to prevent the adhesive of the polyimide tape 5 from peeling at the time of peeling of the second tape 2.

In the lead frame thus formed, the inner leads are fixed before the polyimide film serving as a support member is peeled off, so that a high degree of pattern accuracy can be maintained. In this way, since the fixing is performed without any twisting or distortion, no thermal distortion occurs, the strength is increased, and the inner lead does not deform even during bonding.

[0036]

As described above, according to the method of the present invention, the first surfaces are sandwiched between the etching-resistant plate members.
And a second metal material are adhered, first and second resist patterns are formed on the surface of the first or second metal material, respectively, and etching is performed using these resist patterns as a mask. Therefore, it is possible to form lead frames of different types independently on the front and back independently at the same time, and it is possible to obtain a high-precision lead frame capable of coping with a large number of types in a small amount with high productivity.

[Brief description of the drawings]

FIG. 1 is a diagram showing a manufacturing process of a lead frame according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a main part of the same step.

FIG. 3 is a plan view of a lead frame formed in the same step.

FIG. 4 is a main part view showing a manufacturing process of a lead frame according to another embodiment of the present invention.

FIG. 5 is a view showing a manufacturing process of a lead frame according to a second embodiment of the present invention.

FIG. 6 is a sectional view of a main part showing a lead frame formed by a conventional method.

[Explanation of symbols]

 1a first metal material 1b second metal material 2 polyimide film 3 photoresist 4a first mask pattern 4b second mask pattern 5 polyimide tape 11 die pad 12 inner lead 13 dam bar 14 outer lead 15 side bar 16 Side bar

Claims (5)

(57) [Claims] 1. An attaching step of attaching first and second metal members on both sides of an etching-resistant plate member, and attaching the first and second metal members to a surface of the first or second metal member of the plate member. A resist pattern forming step of forming first and second resist patterns, a pattern forming step of performing etching using the resist pattern as a mask to form desired lead frame patterns including inner leads and outer leads, respectively, Separating the first and second metal materials from the body to form first and second lead frames. 2. The lead frame manufacturing method according to claim 1, wherein said first and second metal materials are materials having different plate thicknesses. 3. The method according to claim 1, wherein the first and second metal members are made of different materials. 4. The method according to claim 1, wherein the first and second resist pattern forming steps are steps of forming patterns different from each other. 5. The method according to claim 1, further comprising a step of attaching an insulating film to a desired region of the inner lead of the first and second metal materials prior to the peeling step.
The method for manufacturing the lead frame described in the above.