JPH05226536A - Manufacture of lead frame - Google Patents

Abstract

PURPOSE:To prevent a lead frame from sticking to a heater block and a bonding part from erroneously recognized by preventing plating liquid from getting into the rear side of the lead frame at the time of silver plating so that the silver may not be transferred to the heater block at the time of wire banding. CONSTITUTION:Relating to manufacture of a lead frame where a lead pattern 16 is formed an a lead frame material 10 by etching and silver plating 12 is made on main places of an inner lead such as a banding surface, etc., the pattern 16 of desired silver plating 12 is formed on one surface of the lead frame material 10 and then the lead frame material 10 is etched so as to leave the pattern of the silver plating 12 for forming the lead pattern 16.

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.

[0002]

2. Description of the Related Art A lead frame is manufactured by etching or press working, but in order to improve the wire bonding property, the wire bonding portion may be silver plated to obtain a product. This silver plating is applied to the wire bonding surface of the inner lead. The surface opposite to the wire bonding surface is sealed, and the wire bonding surface is masked and plated to expose the area to be silver plated. FIG. 5 shows a case where a lead frame is manufactured by an etching method. A resist pattern 3 is formed on a lead frame material 2 (FIG. 5 (a)), and a lead 4 is formed by etching (FIG. 5 (b)). A state in which the surface opposite to the wire bonding surface of the frame is sealed and silver plating 5 is applied (FIG. 5 (c)) is shown.

[0003]

When silver plating is applied to the lead frame, the non-plated surface of the lead frame is sealed and plated as described above, but the lead side surface is not completely removed during this plating. Since it is not possible to seal, the silver plating solution may flow out to the opposite surface, which is not plated, and the back surface of the lead frame may be silver-plated. When wire bonding to the lead frame, put the lead frame on the heater block and hit the wire, but if the back surface of the lead frame has silver plating as described above, it will be There is a problem that silver is transferred to the heater block and adheres to the heater block.

When wire bonding is repeated many times, silver gradually accumulates in the heater block. The silver adhering to this heater block has a function of sticking the lead frame to the heater block, and the lead frame is heated after the wire bonding. This makes it difficult to separate the block from the block and causes deformation of the lead, causing a problem of short-circuiting of the bonding wire. In addition, when wire bonding, the bonder recognizes the position of the inner lead and performs bonding, but if silver adheres to the heater block as described above, the heater block becomes whitish and it is difficult to distinguish it from the silver-plated portion of the inner lead. There is a problem that the lead is erroneously recognized.

Further, according to the conventional silver plating method, the back surface of the lead frame is sealed and the other surface is exposed and plating is performed, so that the entire side surface of the lead is covered with the silver plating 5 as shown in FIG. However, there was a problem that migration was likely to occur. Therefore, the present invention has been made to solve the above problems, and an object of the present invention is to prevent the plating solution from wrapping around to the back surface side of the lead frame during silver plating and to silver-plat the heater block. Another object of the present invention is to provide a method for manufacturing a lead frame, which can solve the problem of adhesion of silver and perform suitable wire bonding and can solve the problem of silver migration.

[0006]

The present invention has the following constitution in order to achieve the above object. That is, in a method of manufacturing a lead frame in which a lead pattern is formed on a lead frame material by etching, and a required portion such as a bonding surface of an inner lead is plated with silver, one surface of the lead frame material is provided with a required silver plating. After forming the pattern, the lead frame material is etched by leaving the silver-plated pattern and forming the lead pattern. Also, one side of the lead frame material is partially silver-plated, resist patterns are formed on both sides of the lead frame material including silver plating according to the lead pattern, and then the silver plating and the lead frame material are etched to form leads. It is characterized by forming a pattern. Further, one side of the lead frame material is silver-plated according to a required silver plating pattern, a resist pattern is further formed on the lead frame material according to the lead pattern, and then the lead frame material is etched to form a lead pattern. It is characterized by doing.

[0007]

When the lead frame material is etched in a predetermined pattern to form the lead pattern, silver is plated in accordance with the lead pattern before the lead frame material is etched, and then the lead frame material is etched. A lead frame having a required lead pattern is formed. By preliminarily silver-plating the lead frame material, it is possible to prevent the silver plating solution from wrapping around the back surface of the lead frame, etc., and it is possible to obtain a lead frame in which only necessary portions of the lead frame are plated with silver.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is an explanatory view showing a first embodiment of a lead frame manufacturing method according to the present invention. In this embodiment, one surface of the lead frame material is partially silver-plated, the silver plating is etched to form a silver plating pattern, and then the lead frame material is etched to form a lead pattern. To do. Figure 1
(a) is a state in which silver plating 12 is partially applied to one surface of the lead frame material 10. FIG. 2A shows a plan view of the lead frame material 10 and the silver plating 12 partially applied. The silver plating 12 is provided on the lead frame in a range where silver plating is finally required.

After the silver plating 12 is partially applied, the lead frame material 10 is formed according to the lead pattern to be formed.
A resist pattern 14 is formed on the surface (FIG. 1 (b)). The resist pattern 14 is provided on both sides of the lead frame material 10 as shown in the figure. FIG. 2B illustrates the state in which the resist pattern 14 is formed on the lead frame material 10. Next, the silver plating 12 that has been partially applied is etched to pattern the silver plating 12. FIG. 1 (c) shows a state where the silver plating 12 is etched. Since the surface of the lead frame material 10 to be etched is exposed by etching the silver plating 12, the lead frame material 10 is etched in this state.

FIG. 1D shows a state in which the lead pattern material 16 is formed by etching the lead frame material 10. The method of etching the lead frame material 10 to form a lead pattern is the same as the conventional method of manufacturing a lead frame. Lead frame material 10
It is possible to form a lead frame having a predetermined lead pattern by etching from both sides. FIG. 1E shows a state in which the resist pattern 14 is dissolved and removed to form a final product. In this way silver plating 12
A lead frame having the required leads provided with is obtained.

According to the manufacturing method of this embodiment, since the silver plating 12 is partially applied to one surface of the lead frame material 10 before the lead pattern 16 is formed, the plating solution is conventionally used for silver plating. It is possible to completely prevent the lead frame from wrapping around on the back surface of the lead frame, and to prevent the silver plating 12 from adhering to the back surface of the lead frame. Further, since the silver plating 12 is formed on the bonding surface on the upper surface of the lead and does not adhere to the side surface of the lead, it is possible to preferably avoid the problem of silver migration. In the above embodiment, the etching of the silver plating 12 and the etching of the lead frame material 10 were performed separately.
Depending on the material of the lead frame material 10, it is possible to etch the silver plating 12 and the lead frame material 10 at the same time.

FIG. 3 shows a second embodiment of the lead frame manufacturing method according to the present invention. In this embodiment, first, when the lead frame material 10 is partially silver-plated, it is previously silver-plated in accordance with the final silver-plating pattern.
FIG. 3A shows a state in which a silver-plated pattern 20 is formed on one surface of the lead frame material 10. The silver-plated pattern 20 is formed by, for example, a mask sealing method. Figure 4
(a) Lead frame material 10 and silver-plated pattern 20
A state in which is formed is shown. In this method, the silver plating is first applied only to the portion requiring the silver plating.

After the silver-plated pattern 20 is formed, a resist is applied by etching to form a lead pattern, which is exposed and developed to form a resist pattern. FIG. 3B shows a state where the resist pattern 22 is formed. Since the resist pattern 22 is etched from both sides, it is formed on both sides of the lead frame material 10. The portion where the silver-plated pattern 20 is formed is covered and protected by the resist pattern 22. FIG. 4B is a plan view showing a state where the resist pattern 22 is formed. Then, the lead frame material 10 is etched to form a lead pattern. Figure 3 (c) shows the state after etching. Further, the resist pattern 22 is dissolved and removed to obtain a product (FIG. 3 (d)).

In FIG. 3 (d), 24 is a stage, 26 is an inner lead, and 20 is silver plating. The obtained lead frame is a product in which silver plating 20 is applied to necessary portions such as a bonding surface as shown in the figure. Also in the case of the method of this embodiment, first, the silver plating pattern 20 is formed on the lead frame material 10.
Since the lead frame material 10 is etched to form the lead pattern after the formation, the problem of silver plating on the back surface of the lead frame can be solved.
In this embodiment, after the silver-plated pattern 20 is formed, the lead frame manufacturing method by the conventional etching method can be applied as it is after the step of forming the resist pattern 22. INDUSTRIAL APPLICABILITY The lead frame manufacturing method according to the present invention can be applied to lead frames having various lead patterns, and the portion to be silver-plated can be appropriately set and used according to the product.

[0015]

As described above, according to the method of manufacturing a lead frame of the present invention, it is possible to completely prevent the silver plating provided on the lead or the like from adhering to the back surface of the lead frame. Silver is no longer transferred from the lead frame to the heater block,
It is possible to solve the problem that the lead frame sticks to the heater block during wire bonding and that the bonding portion is erroneously recognized during wire bonding. Further, the silver plating is formed only on the bonding surface of the lead frame and does not attach to the side surface of the lead, so that the problem due to silver migration can be solved, and so on.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example of a method of manufacturing a lead frame.

FIG. 2 is an explanatory diagram showing a state in which a lead frame material is plated with silver.

FIG. 3 is an explanatory view showing another embodiment of the method of manufacturing the lead frame.

FIG. 4 is an explanatory diagram showing a state where a silver plating pattern is formed on a lead frame material.

FIG. 5 is an explanatory diagram showing a conventional example in which a lead frame is plated with silver.

[Explanation of symbols]

 2, 10 Lead frame material 3, 14, 22 Resist pattern 4 Lead 5 Silver plating 12 Silver plating 16 Lead pattern 20 Silver plating pattern 24 Stage 26 Inner lead

Claims (3)

[Claims] 1. A method of manufacturing a lead frame, wherein a lead pattern is formed on a lead frame material by etching, and silver plating is applied to a required portion such as a bonding surface of an inner lead. A method of manufacturing a lead frame, comprising forming a pattern of silver plating, and then etching the lead frame material while leaving the pattern of silver plating to form a lead pattern. 2. A lead frame material is partially silver-plated on one surface, and a resist pattern is formed on both surfaces of the lead frame material including the silver plating according to the lead pattern, and then the silver plating and the lead frame material are etched. The lead frame is formed by forming a lead pattern. 3. A lead pattern is formed by applying silver plating on one surface of a lead frame material according to a required silver plating pattern, forming a resist pattern on the lead frame material according to the lead pattern, and then etching the lead frame material. The method for manufacturing a lead frame according to claim 1, wherein the lead frame is formed.