JPH0864751A - Manufacture of lead frame - Google Patents

Abstract

PURPOSE: To provide the manufacturing method for a lead frame having the clam bar of insulating resin at least on either of an inner lead and an outer lead in a thin multipin lead frame. CONSTITUTION: In the manufacture of a lead frame 10 having an insulating resin dam bar at least on either of an outer lead 3 and an inner lead 4, a lead frame having no dam bar is inserted in a recessed part having the recess in the shape of the lead frame with no dambar and in the shape corresponding to the dam bar 1, and light or ultraviolet ray hardening insulating resin 7 is filled in the recessed part and the resin is leveled by a squeegee.

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 lead frame having a thin plate and having at least one inner lead or outer lead having a dam bar made of an insulating resin. It relates to a manufacturing method.

[0002]

2. Description of the Related Art An example of a manufacturing process of a lead frame will be briefly described. First, the surface of the metal plate that will be the lead frame is degreased and surface-treated. Then, on both sides of the metal plate,
For example, a water-soluble negative photosensitive resin composed of polyvinyl alcohol and ammonium dichromate is applied.
Next, using two masks with the light-transmitting portion in the pattern of the lead frame and the light-shielding portion other than the pattern portion of the lead frame, apply one mask to one side of the metal plate, and the other side of the metal plate. Another mask is applied to the position opposite to each other, and UV exposure is performed from both surfaces to photo-cur the photosensitive resin in the pattern frame portion of the lead frame.

Next, by developing, the photosensitive resin in the uncured portion, that is, the photosensitive resin other than the portion which becomes the pattern of the lead frame is removed. Then, the metal plate is etched from both sides using an etching solution, the metal plate other than the part to be the lead frame pattern is removed by etching, and the part other than the part to be the lead frame pattern is penetrated to form the part to be the lead frame pattern. Leave. Next, the photosensitive resin is peeled off. Then, a part of the inner lead is plated with a noble metal by a known method, for example, a method of spraying a plating solution, and the metal plate is punched into a required shape to obtain a lead frame.

Next, in a lead frame for a semiconductor IC, an IC chip is placed on the lead frame and the IC
After the chip and the lead frame are wire-bonded, they are molded with an insulating resin. Therefore, when the resin is molded on the lead frame, the insulating resin is prevented from flowing out from the gap between the outer leads.
As shown in FIG. 5, a bank (hereinafter referred to as a dam bar) is added to the lead frame so as to cross the outer lead 3. Next, in the dam bar 1 in FIG. 3, the outer leads 3 are connected to each other, and if they are used as they are, the outer leads 3 will have the same electric potential and will be short-circuited. It has been cut and removed.

However, in recent years, the lead frame has a thin plate thickness and tends to have a large number of pins. For example, in a lead frame called a layer for a ceramic package, the package size is large, the number of pins is 200 to 300 or more, and the plate thickness is 10 as well.
It is very thin, from 0 μm to 150 μm. Therefore, the pitch between the outer leads is also narrowed, and it is becoming very difficult to cut and remove the dam bar using a punching die.

Further, as described above, the partial noble metal plating treatment applied to the tips of the inner leads is usually carried out by a method of spraying a noble metal plating solution onto the tips of the inner leads. Therefore, at the time of noble metal plating, a masking jig is brought into close contact with the surface of the lead frame to be plated with noble metal, and plating is performed by spraying the noble metal plating solution onto the tip of the inner lead.

In this case, however, the masking jig can be used to prevent the formation of the plating film on the unnecessary portion of the upper surface of the lead frame, but the precious metal plating solution leaks to the side surface of the inner lead and the plating solution flows to the side surface. It was difficult to prevent the formation of unnecessary plating film on the side surface of the inner lead.

Therefore, when the unnecessary plating liquid leaks to the side surface of the inner lead excessively, and, for example, when the unnecessary side surface plating film is formed up to the vicinity of the outer lead, when the insulating resin is molded, the resin does not come into contact with the resin. Poor adhesion of the lead frame may occur, resulting in a problem in durability as an IC package.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of manufacturing a lead frame in which a dam bar is made of an insulating resin in a multi-pin lead frame having a thin plate thickness, thereby solving the above problems. To obtain a lead frame that does not have.

[0010]

That is, the present invention provides a method of manufacturing a lead frame having a dam bar made of an insulating resin on at least one of the outer lead and the inner lead, and having a recess in a shape corresponding to the dam bar, In addition, the lead frame without a dam bar is inserted into a recessed portion having a recess in the shape of a lead frame without a dam bar, and the insulating resin is filled by scratching the recess having a shape corresponding to the dam bar with a squeegee, and then light or ultraviolet rays are used. The present invention is intended to solve the above-mentioned problems by providing a method for manufacturing a lead frame, which is characterized in that the resin filled with is cured.

[0011]

According to the present invention, by attaching the dam bar using the insulating resin to the outer lead of the lead frame, it is not necessary to perform the cutting and removing work of the metal dam bar using the metal mold or the like which is performed with the metal dam bar. . Next, when the inner lead is provided with a connecting portion using an insulating resin (hereinafter, referred to as an inner lead dam bar for convenience),
During noble metal plating, it is possible to prevent the sprayed noble metal plating liquid from leaking to the inner lead side surface. In addition, since the tip of the inner lead, which has become extremely thin due to the increase in the number of pins, is fixed with resin, it is possible to suppress variations in the inner lead during the manufacturing process, and it is possible to prevent inner vibration due to external pressure vibration or the inclusion of the transport roller during the manufacturing process. It is possible to prevent deformation of the lead.

Further, according to the present invention, when the concave portion is filled with the insulating resin, the excess resin applied to the lead portion can be scraped off by scraping it with a squeegee.
Therefore, the insulating resin does not adhere to and remain on the excess portion of the lead frame, and it is possible to prevent defective plating and defective bonding due to excessive resin adhesion.

Further, in the present invention, if a light or ultraviolet curable resin is used as the insulating resin forming the dam bar, the resin filled in the concave portion can be cured in a short time by irradiating it with light or ultraviolet light.

[0014]

Embodiments of the present invention will be described with reference to the drawings. In order to explain the embodiment of the present invention, FIG. 1 below illustrates only a part of the inner lead and the outer lead of the lead frame.

First, as shown in FIG. 1A, a lead frame 10 for molding is prepared. In the lead frame 10 for molding, a dam bar 1 for preventing resin outflow at the time of resin molding is provided in the outer lead 3 portion, and the dam bar 1 connects the outer leads 3 with each other. Also,
In order to prevent the plating solution from leaking to the side surface of the inner lead 4 when the plating solution applied to the precious metal plating area 5 of the inner lead 4 is sprayed, the inner lead dam bar 2 is attached to the noble metal plating area 5 of the inner lead 4. It is provided at the boundary and the inner lead dam bar 2 is used for the inner lead 4
Connecting comrades.

Next, the lead frame 1 for molding as described above.
As shown in FIG. 1B, 0 is embedded in, for example, a silicone resin, and then the molding lead frame 10 is removed from the silicone resin. As a result, the female mold 6 is obtained as a concave mold in which the mold of the mold-taking lead frame 10 remains as a concave mold.

Next, a lead frame 8 for obtaining a final product, which does not have the dam bar 1 and the inner lead dam bar 2 and has the same shape as the above-described lead frame 10 for molding, except for the above, is obtained. Fit in the female mold 6 of. In this state, in the female die 6, the dam bar 1 and the inner lead dam bar 2 remain as recesses.

Then, as shown in FIG. 1 (c), with the lead frame 8 fitted in the female die 6, a concave portion corresponding to the dam bar 1 and the inner lead dam bar 2 on the female die is, for example, an ultraviolet curing type. Such as epoxy resin,
An insulative light or ultraviolet curable resin 7 is filled.

Then, as shown in FIG. 1 (d), the female mold 6
And by squeezing the lead frame 8 with a squeegee 9, the recess 7 is filled with the resin 7 densely, and
The excess resin on the lead frame 8 is scraped off.

Next, by irradiating light or ultraviolet rays, the resin 7 filled in the above-mentioned recesses is cured. Next, the lead frame 8 with the resin 7 is taken out from the female die 6 to obtain the lead frame with the dam bar 1 made of an insulating resin and the dam bar 2 for the inner lead shown in FIG. Next, the lead frame is subjected to manufacturing processes such as noble metal plating and resin molding by a known method to obtain an IC package.

In the above embodiment, the squeegee 9 is used to scrape off the excess resin after the recess 7 is filled with the resin 7. However, by using the squeegee 9, the recess is filled with the resin and the excess resin is removed. Both steps of scraping off the different resin may be performed at the same time. Further, in the above embodiment, both the dam bar 1 and the inner lead dam bar 2 are formed on the lead frame 8, but either one may be formed as necessary.

[0022]

According to the present invention, by attaching a dam bar made of an insulating resin to the outer leads of the lead frame, the metal dam bar can be cut and removed using a punching die or the like, which has been done with a metal dam bar. Since it is not necessary to carry out, it is possible to prevent the deformation defect of the ultra-fine outer lead, which has been caused by the conventional cutting and removal of the dam bar using the punching die, and it is also possible to improve the production efficiency. Next, when the inner lead dam bar made of insulating resin is attached to the inner lead, it is possible to prevent the sprayed precious metal plating liquid from leaking to the side surface of the inner lead during noble metal plating, and the durability of the IC package due to defective resin molding. Can be prevented. Also, since the tip of the inner lead, which has become extremely thin due to the increase in the number of pins, is fixed with resin, it is possible to suppress variations in the inner lead during the manufacturing process, and it is possible to prevent inner pressure vibrations and entrainment of the transport roller during the manufacturing process. It is possible to prevent deformation of the lead.

Further, in the present invention, when the concave portion is filled with the insulating resin, the squeegee is used to scrape away the excess resin. Therefore, the insulating resin does not adhere to and remain on the excess portion of the lead frame, and it is possible to prevent defective plating and defective bonding due to excessive resin adhesion.

Further, in the present invention, if a light or ultraviolet curable resin is used as the insulating resin forming the dam bar, the resin filled in the concave portion can be cured in a short time by irradiating it with light or ultraviolet light. It can be said that the present invention is practically excellent in manufacturing a multi-pin lead frame.

[0025]

[Brief description of drawings]

1A to 1D are perspective explanatory views showing an embodiment of a method of manufacturing a lead frame provided with an insulating resin dam bar of the present invention in the order of steps.

FIG. 2 is a plan view showing an embodiment of a lead frame provided with an insulating resin dam bar of the present invention.

FIG. 3 is a plan view showing an example of a conventional lead frame provided with a dam bar.

[Explanation of symbols]

 1 Dam Bar 2 Dam Bar for Inner Lead 3 Outer Lead 4 Inner Lead 5 Plating Area 6 Female 7 Insulating Resin 8 Lead Frame 9 Squeegee 10 Lead Frame for Mold Making

Claims (3)

[Claims] 1. A method of manufacturing a lead frame having a dam bar made of an insulating resin on at least one of an outer lead or an inner lead, wherein the shape has a recess corresponding to the dam bar, and the recess has a recess in the shape of the lead frame having no dam bar. A method of manufacturing a lead frame, comprising: inserting a lead frame having no dam bar into a concave portion having a groove; filling a recess having a shape corresponding to the dam bar with an insulating resin; and hardening the insulating resin. 2. The method for manufacturing a lead frame according to claim 1, wherein the insulating resin is a light or ultraviolet curable resin. 3. The method of manufacturing a lead frame according to claim 1, wherein the insulating resin is applied to a recess having a shape corresponding to a dam bar, and then the recess is filled with the squeegee to smooth it.