JPH0730054A - Manufacture of lead frame - Google Patents

Abstract

PURPOSE:To prevent insulator from being left on the resin feed side of a lead by a method wherein photosensitive resin fed onto a lead frame is made to start being exposed to light from its side opposite to its other feed side, and an insulator is formed to link leads together. CONSTITUTION:Insulating, photosensitive resin 20 cured by ultraviolet ray or the like is fed over a lead frame 10. The photosensitive resin 20 fed onto the lead frame 10 is made to start being exposed to light to be cured from its side opposite to its other feed side, whereby an insulator formed of photosensitive resin 20 is formed. Uncured photosensitive resin 20 is removed by cleaning. As mentioned above, the photosensitive resin 20 is made to start being exposed to light to be cured from its side opposite to its other feed side, so that the feed side of resin 20 fed onto the lead frame 10 is not exposed to light, only resin filled in between leads due to its own weight is cured by light exposure to link the leads together. Therefore, insulator is hardly left on the resin feed side of leads.

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 having an insulator connecting leads.

[0002]

2. Description of the Related Art When connecting the leads of a lead frame with an insulator, there are two types, one for connecting inner leads and one for connecting outer leads. First, the one that connects the first inner leads is a lead frame as disclosed in Japanese Unexamined Patent Publication No. 2-222569, and the reason why such a lead frame is required is that the lead pitch is becoming narrower. In the frame, the distance between the leads is becoming very narrow, and the inner leads are deformed during handling such as transportation in the state of the lead frame or during resin sealing after mounting the semiconductor chip. This is to prevent short-circuiting with the adjacent lead. Insulators at this time are often tapes such as polyimide, but in recent years productivity,
Insulating resins, such as silicone resins and epoxy resins as disclosed in JP-A-2-222569, are often used because of problems such as cost.

To connect the second outer lead, an insulator is provided outside the resin sealing line as disclosed in Japanese Patent Laid-Open No. 1-203756. The reason why such a lead frame is required is to prevent the resin from leaking from between the leads to the outside of the boundary where the resin should be originally sealed at the time of resin sealing,
It is called a dam bar or tie bar. The dam bar was formed by leaving the metal of the dam bar part when processing the lead frame from a metal plate by etching, stamping, etc., and the method of cutting the dam bar with a mold after resin sealing was adopted, but narrowing the pitch As it progresses, it becomes difficult to cut the dam bar, and there is a background that the dam bar is provided by the insulating resin.

For the above reasons, it has been developed to connect the leads with an insulator, but in the manufacturing method thereof, as shown in Japanese Patent Publication No. 4-64468, after supplying with a dispenser, A method of sandwiching with a pressing plate and a method of correcting the step between the leads by magnetic force as shown in Japanese Patent Laid-Open No. 222522/1989 have been adopted.

[0005]

However, the manufacturing method as described above has a problem that the resin remains not only between the leads but also on the resin supply surface side. That is, the above-mentioned JP-A-2-222569 and JP-A-1-3027.
The resin in the technology disclosed in Japanese Patent Publication No. 56 and Japanese Patent Publication No. 4-64468 requires an appropriate viscosity in order to be filled between the leads, but a resin having such viscosity is supplied by a dispenser. Then, as a result of an experiment conducted by the inventors, a resin of about 100 μm to 150 μm usually remained on the lead frame on the supply surface side. In this way, if the resin remains on the lead frame on the resin supply surface side, in the type in which the insulator is first provided on the inner lead side, the cause of obstructing the flow of the sealing resin at the time of resin sealing Then, voids are generated in the sealing resin and the reliability of the package is lowered. Specifically, heat is generated during mounting of the IC package to crack the package, or moisture is accumulated in the void portion over time. There was a problem of causing insulation failure.

Further, in the type in which the insulator is provided as the dam bar, the resin on the lead frame is pressed by the mold and crushed when sandwiched by the mold for sealing at the time of resin sealing. The resin is greatly crushed, crushed, and adheres to the mold, and as it is continuously manufactured, the mold does not fit well, there is a gap, leakage of the sealing resin occurs, There is a problem that the package thickness varies. Further, the crushed resin pieces may impose an excessive force on the mold, which may affect the accuracy of the mold. In recent years, particularly in TAB and the like, thinning of packages has been rapidly advanced, and even packages having a package thickness of about 1 mm are used. Particularly in such a thin package, the resin of 100 μm to 150 μm remaining on the resin supply surface side of the lead frame is crushed and scattered, which seriously affects the reliability of the package thickness.

The present invention has been made in view of the above problems, and an object of the present invention is to insulate the surface of the leads on the resin supply side in a lead frame having an insulator for connecting the leads. It is to provide a method for manufacturing a lead frame in which the body does not remain.

[0008]

That is, in order to solve the above problems in the present invention, in the first invention, a lead frame having a plurality of leads independent from each other and an insulator connecting the leads is provided. In the manufacturing method, a step of supplying a photosensitive resin, which is insulative and hardened by ultraviolet rays, onto the lead frame. A step of forming an insulator made of the cured photosensitive resin by exposing and curing the photosensitive resin supplied onto the lead frame from the surface opposite to the supply side. A step of washing and removing the uncured photosensitive resin. The present invention provides a method for manufacturing a lead frame, including the steps of.

According to a second aspect of the present invention, the method of manufacturing the lead frame according to the first aspect is characterized in that at least a part of the insulator is formed outside a resin sealing line. is there.

A third aspect of the present invention is the method for manufacturing a lead frame according to the first aspect, wherein the insulator is formed in the vicinity of the tip of the inner lead.

[0011]

According to the first aspect of the present invention, since the photosensitive resin is exposed and cured from the surface opposite to the supply side, the resin on the lead frame on the supply side is exposed. Only the resin buried between the leads under its own weight is exposed,
Since it hardens and connects the leads, the insulator does not remain on the surface of the leads on the resin supply side. Also, claim 2
According to the invention of claim 1, on the premise of the invention of claim 1, at least a part of the insulator is formed outside the resin sealing line. The mold resin can be prevented from flowing out between the leads, and a package having a good shape can be obtained. Furthermore, according to the invention according to claim 3, on the premise of the invention according to claim 1, since the insulator is formed in the vicinity of the inner lead, the insulator is made of resin when the resin is sealed. It is possible to obtain an excellent insulator for fixing the leads, which can fix the tips of the inner leads and prevent the inner leads from contacting each other without obstructing the flow.

[0012]

【Example】

Example 1 A copper alloy lead frame having a plate thickness of 0.15 mm was formed by etching, and then coining was performed to secure a flat width at the tip of the inner lead. The thus obtained lead frame had a flat width of 120 μm at the tips of the inner leads and a pitch of 220 μm at the tips of the inner leads. While holding this lead frame (10), a dispenser (30) is used from above the lead frame, and the distance between the inner circumference of the photosensitive resin and the resin sealing line is 0.5 outside the resin sealing line in the horizontal direction.
An ultraviolet curable photosensitive resin (20) (trade name; UC310, manufactured by Toyo Ink Mfg. Co., Ltd.) having a viscosity of 60 ps was supplied in a width of 300 μm at a position such that the width became mm. The width of the outer lead of the photosensitive resin forming portion is 250 μm,
The pitch was 500 μm. The photosensitive resin was filled between the outer leads by its own weight. After the photosensitive resin (20) is supplied to the lead frame (10) in this way,
Ultraviolet light was exposed from below the lead frame using a high pressure mercury lamp. The amount of light at this time was 2000 mJ.
Then, it wash | cleaned using ethanol and the uncured photosensitive resin (22) on the upper surface of the lead frame (10) was removed. As a result, the resin (24) did not remain on the upper surface of the lead frame, and the insulator (24) made of the cured photosensitive resin was formed only between the outer leads. Then 130
Baking was performed at 30 ° C. for about 30 minutes. In this way, a lead frame (10) in which the leads of the outer leads were connected by the insulator (24) was obtained. In this embodiment, the distance between the inner circumference of the photosensitive resin and the resin sealing line is 0.5.
The insulator is provided at a position of mm, but it is not particularly limited as long as at least a part of the insulator is formed outside the resin sealing line. However, since the resin for sealing protrudes into the gap between the inner circumference of the photosensitive resin and the resin sealing line,
The gap is preferably as small as possible, and the inner periphery of the photosensitive resin is preferably inside the resin sealing line.

Example 2 The same material and process as in Example 1 were used to feed the photosensitive resin to the inner lead portion. The supply position was about 3 mm from the tip of the inner lead using a dispenser. At this time, the position of the inner lead from the tip may be such that the bonding area is left at the tip, but even if it is too far from the tip, the original purpose of preventing deformation of the inner lead is impaired. Become. Then, as in Example 1,
It was exposed to ultraviolet light from below the lead frame, washed and removed with ethanol, and baked at 130 ° C. for about 30 minutes. In this way, the lead frame (1) in which the leads of the inner lead are connected by the insulator (24)
0) was obtained. It should be noted that the present invention is not limited to the above-described embodiment. For example, although the material of the lead frame is the embodiment of the copper alloy in the above-mentioned embodiment, it may be 42 alloy or the like.

[0014]

According to the present invention, since the resin insulator is formed only between the leads of the lead frame, it is possible to manufacture a lead frame having a good resin sealing property. That is, in the type in which the insulator is provided on the inner lead side, the flow of the sealing resin is not obstructed at the time of resin sealing, and therefore the package cracks due to the heat when mounting the IC package or the void portion is It is possible to obtain a lead frame in which water does not accumulate over time. Further, in the type in which an insulator is provided as a dam bar, when sandwiched by a mold for sealing at the time of resin sealing, the resin is pressed by the mold and crushed and adheres to the mold, and the mold is There are no problems such as poor fitting, gaps, leakage of sealing resin, and variation in package thickness.

[Brief description of drawings]

1A and 1B show a first embodiment of the present invention, in which FIG. 1A is an explanatory view represented by a cross section showing a step of supplying a photosensitive resin to a lead frame, and FIG. 1B shows an exposure step. It is an explanatory view expressed in a section, and (C) is an explanatory view expressed in a section of a lead frame in which an insulator is formed.

[Explanation of symbols]

 10 Lead frame 20 Photosensitive resin 22 Unhardened photosensitive resin 24 Insulator 30 Dispenser

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Claims (3)

[Claims] 1. A method of manufacturing a lead frame comprising a plurality of leads independent of each other and an insulator connecting the leads to each other, wherein a photosensitive resin which is insulative and hardened by ultraviolet rays is supplied onto the lead frame. Process. A step of forming an insulator made of the cured photosensitive resin by exposing and curing the photosensitive resin supplied onto the lead frame from the surface opposite to the supply side. A step of washing and removing the uncured photosensitive resin. A method of manufacturing a lead frame, the method including: 2. The method for manufacturing a lead frame according to claim 1, wherein at least a part of the insulator is formed outside the resin sealing line. 3. The method for manufacturing a lead frame according to claim 1, wherein the insulator is formed near the tip of the inner lead.