KR20000038929A - Manufacturing method of semiconductor package - Google Patents

Abstract

PURPOSE: A manufacturing method of semiconductor packages is provided to prevent damage of a plating layer on outer leads. CONSTITUTION: In a manufacturing method of semiconductor packages(20), a process of forming outer leads(15) into a proper form precedes a process of plating the outer leads(15) not to cause damage to a plating layer(27) on the outer leads(15). A semiconductor chip is embedded in a package body(26) and electrically connected with the outer leads(15) through bonding wires and inner leads. In the forming process, a connection bar(16) is separated from a frame(18) at its end(16a), and the outer leads(15) are then transformed into a form suitable for mounting onto an external electronic device. However, the outer leads(15) are electrically connected with the frame(18) through a zigzag bar(24) linked with the connection bar(16). Since electric power is supplied to the outer leads(15) through the zigzag bar(24), the plating process can be performed after the forming process and the plating layer(27) is free from damage in the forming process.

Description

Method for manufacturing semiconductor package

The present invention relates to a method for manufacturing a semiconductor package, and more particularly, to a semiconductor package capable of suppressing damage of a plating film plated on a surface of an external lead by a mold of a forming equipment in a forming process after the plating process is completed. It relates to a manufacturing method.

It takes several steps to produce a single semiconductor package, which can be divided into chip fabrication process and package assembly process. The chip manufacturing process is literally a process associated with the manufacture of a semiconductor chip, such as the design of the chip and the formation of wiring. The package manufacturing process is not directly related to the manufacture of the chip, but is necessary to protect the chip from the external environment and to optimize and maximize the performance of the chip.

The package manufacturing process can be divided into a chip / wire bonding step, a molding step, a testing step, and the like. In general, the package manufacturing process 30 using the lead frame, as shown in FIG. 1, separates the external lead from the frame of the lead frame after the chip wire bonding process and the forming process 31 are completed. Trim / Form Steps (32, 34) and Plating Steps (33) for External Leads to be bent to the Mounting Form, and the Plating Process (33) is a Trim Process (32) And between the forming process 34. Electroplating is mainly utilized as the plating process 33, and the plating film of tin material is plated thinly on the external lead.

By the way, since the forming process of bending an external lead to a mounting form is performed after a plating process, there exists a possibility that the plating film plated on the surface of an external lead may be damaged. That is, in the forming process, the mold of the forming equipment applies mechanical force directly to the upper and lower surfaces of the external lead to bend the external lead, and the mechanical contact area between the mold and the external lead of the forming equipment is wide, so that The plated film thinly plated on the surface is pushed into the mold of the forming equipment may cause a defect that the plated film is scratched or peeled off. In particular, a lead frame made of a copper material having excellent electrical characteristics is more severe.

Accordingly, it is an object of the present invention to provide a method of manufacturing a semiconductor package capable of suppressing damage of a plated film plated on an external lead.

1 is a process chart showing a method for manufacturing a semiconductor package according to the prior art;

2 is a process chart showing a method of manufacturing a semiconductor package according to an embodiment of the present invention;

3 is a plan view illustrating a lead frame used in a process of manufacturing the semiconductor package of FIG. 2;

4 to 7 are views showing each process step according to the manufacturing method of FIG.

4 is a perspective view showing a lead frame in which a package body is formed by a molding process;

5 is a perspective view illustrating a state in which a dam bar is cut by a trim process;

6 is a perspective view showing a state in which an external lead is bent by a primary forming process;

7 is a perspective view illustrating a state in which a semiconductor package is separated from a lead frame by a plating process and a secondary forming process.

Description of the main parts of the drawing

10: lead frame 12: die pad

13: guide hole 14: tie bar

15: lead 16: connecting bar

17: Dambar 18: Outer Frame

19: inner frame 20: semiconductor package

24: Flex Bar 26: Package Body

28: slit

In order to achieve the said objective, the manufacturing method of the semiconductor package which can be performed by changing the order of a conventional forming process and a plating process came to be considered. That is, if the plating process for the external lead is performed after the process of bending the external lead and the semiconductor package having the plating process is separated from the lead frame, the plating film plated on the surface of the external lead can be reduced. It was supposed to be. On the other hand, in order to bend the external lead must first proceed after separating from the frame of the lead frame, when using a conventional lead frame there is no passage for supplying electricity to the external lead in the plating process. Therefore, a method of manufacturing a semiconductor package using a lead frame having an electrical connection passage capable of electrically connecting the frame of the lead frame and the external leads while bending the external leads before the plating process is provided.

That is, the present invention provides a method of manufacturing a semiconductor package using a lead frame, comprising: (A) a package body in which a semiconductor chip is sealed with a liquid molding resin, a package body in which a plurality of packages are formed at predetermined intervals, and a plurality of package bodies. A frame having an outer frame connected to a tie bar protruding to an edge of the package body and an inner frame connected to the outer frame to distinguish the package body, and electrically connected to the semiconductor chip; A plurality of external leads protruding in all directions from the package body and formed along the outer periphery of the package body to connect between the external leads and the external leads, and to prevent the molding resin in the liquid from counting outside in a molding process. Bar and the end of the outer lead, the sock end to the frame Comprising the steps of: preparing a lead frame composed of; connected connecting bar, and at a predetermined distance from the connecting bar on the outside of the lid is projecting direction coupled to the frame, a plurality of curved bar having at least one winding; (B) cutting the dambar between the outer leads; (C) cutting the connection bars connecting the outermost outer lead and the frame among the outer leads, and bending the outer leads; (D) plating the surface of the external leads with tin by supplying electricity through a bending bar connecting the frame and the external leads; And (E) cutting the connecting bar and tie bar connecting the ends of the external lead to separate semiconductor packages from the lead frame, wherein when bending the external leads in the step (C), the The method provides a method of manufacturing a semiconductor package, characterized in that the bent bar is extended while the bent bar is bent so that the bent bar comes down to be attached to the frame.

In the method of manufacturing a semiconductor package according to the present invention, in step (C), the external lead is bent into a hook wing type.

In the method of manufacturing a semiconductor package according to the present invention, it is preferable that the bending bar is formed to have a bend in the form of a letter.

In the method for manufacturing a semiconductor package according to the present invention, before the step (C) and the step (D) are performed, the step of removing the fresh residue remaining in the external lead in the molding step of the step (A) is performed. It is preferable.

Hereinafter, with reference to the accompanying drawings will be described in detail an embodiment of the present invention.

2 is a process diagram illustrating a manufacturing process of a semiconductor package according to an embodiment of the present invention. 3 is a plan view illustrating a lead frame used in a process of manufacturing the semiconductor package of FIG. 2. 4 to 7 are diagrams illustrating each step according to the manufacturing process of FIG. 2. A method of manufacturing a semiconductor package according to an embodiment of the present invention will be described with reference to FIGS. 3 to 7. In addition, like reference numerals denote like elements throughout the drawings.

First, the lead frame used in the present invention will be described with reference to FIG. 3. In the lead frame 10, a die pad 12 to which a semiconductor chip is attached is formed at a center portion thereof. The die pad 12 has four corner points and is supported by tie-bars 14 connected to each corner point, respectively. The tie bar 14 extends radially outward at each corner point of the die pad 12.

A plurality of leads 15 extend radially toward the die pad 12 at predetermined intervals from the die pad 12. In order to support the lid 15 and prevent the liquid molding resin from overflowing in the molding step, a dam bar 17 is formed in the middle portion of the lid 15. Dam bar 17 is formed in the form of a skeleton connecting each lead 15, and is removed after the molding process. The lead 15 is divided into an inner lead 15b extending toward the die pad 12 around the dam bar 17 and an outer lead 15a extending in the opposite direction. The inner lead 15b is a portion electrically connected to the semiconductor chip adhering to the die pad 12 and sealed by a liquid molding resin in a molding process, and the outer lead 15a is bent into a predetermined shape to form an external electronic device. And the external connection terminal connecting the semiconductor chip.

An outer frame 18 connecting the plurality of unit lead frames to the outer side of the lead frame 10 and an inner lead frame 19 separating the unit lead frames are provided. In the outer frame 18, guide holes 13 necessary for the transfer of the lead frame 10 are partially formed at predetermined intervals. The ends of the outer lead 15a are connected to and supported by the inner frame 19 and the outer frame 18. In addition, a plurality of slits 28 (Slits) are formed along the frame at the end of the external lead 15a so that the semiconductor package in which the semiconductor package manufacturing process is completed in the lead frame 10 can be easily separated into individual semiconductor packages. .

As described above, the components of the lead frame 10, the die pad 12, the tie bar 14, the lead 15, the dam bar 17, the outer frame 18 and the inner frame 19 are made of iron or copper. It is formed by an etching or stamping method using a material having excellent electrical conductivity such as a base alloy. Silver (Ag) may be plated at the end of the inner lead 15b to improve the connection with the bonding wire. The lead frame 10 is formed in parallel with a plurality of unit lead frames connected to the outer frame 18, and is divided into unit lead frames by the inner frame 19.

Then, the spacing of the slits 28 of the lead frame used in the embodiment of the present invention is wider than in the prior art, and the portion 16 (hereinafter referred to as "connection bar") connecting the ends of the outer lead 15a. And a bar 24 (hereinafter referred to as a “bending bar”) connecting the inner frame 19 to each other are formed to have at least one bend. In the embodiment of the present invention, the flexure bar 24 has a L-shape and two flexure bars are formed on each side where the outer leads 15a are formed. Both end portions 16a of the connecting bar 16 are connected to the inner and outer frames 18 and 19. As described above, the reason why the slits 28 are formed wider than the conventional one and the flexure bar 24 is formed will be described later. However, the forming process of bending the external leads 15a is performed before the plating process, and the external leads 15a are formed. It is a component devised by the present invention in order to enable the plating process for the external lead 15a after bending.

Referring to the manufacturing method 40 of the semiconductor package using the lead frame 10 having such a structure, as shown in FIG. 4, a semiconductor chip is mounted on the die pad 12, and the semiconductor chip and the internal lead ( In a state in which 15b) of FIG. 3 is bonded with a bonding wire, the package body 26 is formed by sealing a portion in which a semiconductor chip is mounted with a liquid molding resin. The same as the manufacturing process of the conventional semiconductor package described above, and the molding process proceeds to a transfer molding step.

Next, as shown in FIG. 5, a trimming process of cutting the dam bar 17 located at the outer side of the package body 26 is performed.

Next, as shown in FIG. 6, a primary forming process is performed. In other words, the connecting bar portion 16a connecting the outermost outer lead and the frames 18 and 19 among the outer leads 15a may be used. Cutting to separate from the frame (18, 19). At this time, the outer leads 15a are connected to the frames 18 and 19 by the bending bars 24. The external leads 15a connected to the connection bars 16 are bent in a batch to conform to the mounting form of the external electronic device. In the embodiment of the present invention, the external leads 15a are collectively bent in a gull wing type. On the other hand, since the connecting bars 16 connecting the external leads 15a are connected to the frames 18 and 19 by the bending bars 24, when the external leads 15a are collectively bent, the bending bars ( 24 extends along the direction in which the outer leads 15a are bent, and the outer leads 15a are connected to the frames 18 and 19 by the bending bar 24. Of course, the length of the bending bar 24 is preferably formed to have a length enough to connect the bent outer lead (15a) to the frame (18, 19). The thickness of the flexure bar 24 is well spread within a range enough to proceed with the first forming process, and thinly formed so as to prevent other portions, especially the frames 18 and 19, from being wrinkled in the first forming process. It is preferable.

Next, the plating process for the external lead 15a is performed. 44 That is, since electricity passes through the bending bar 24 connecting the frames 18 and 19 to the external leads 15a, the package body is carried out. A portion of the lead frame 10 except for (26) can be electroplated with tin. The bending bar 24 may be understood to be a part that enables the semiconductor package manufacturing process to proceed in the order of the primary forming process and the plating process for the external lead 15a. Reference numeral 27 in FIG. 7 denotes a plating film.

On the other hand, since the dam bar (17 in FIG. 4) in the molding process prevents the liquid molding resin from counting out but does not count completely, the dam bar 17 and the outer leads 15a close to the package body 24 are molded. Fresh resin 25 (Flash) remains. Therefore, before the plating process, a deflash step of chemically or mechanically removing the freshness 25 remaining in the external leads 15a is performed. Of course, the defresh process and the plating process may be performed at a time by using a plating apparatus capable of performing the defresh process and the plating process together.

Lastly, as shown in FIG. 7, a secondary forming process for separating the semiconductor package 20 attached to the lead frame 10 into individual semiconductor packages is performed. The semiconductor package 20 is separated from the lead frame 10 by cutting the connecting bar 16 connecting the ends and the tie bar 14 supporting the package body 24.

On the other hand, in the second forming step, only the end portion of the outer lead 15a is cut out by cutting means (not shown), and the mechanical contact area between the cutting means and the outer lead 15a can be reduced, so that the plated film of the outer lead (27) is less likely to be damaged.

Therefore, according to the manufacturing method of the present invention, since the plating process is performed after the first forming step of bending the external lead, the plating film plated on the surface of the external lead can be suppressed from being damaged.

Claims (4)

A semiconductor package manufacturing method using a lead frame, (A) a package body in which a semiconductor chip is sealed with a liquid molding resin, the package body having a plurality formed at predetermined intervals; A frame having an outer frame formed along an outer side of the package body and connected to a tie bar protruding to an edge of the package body, and an inner frame connected to the outer frame to distinguish the package body; A plurality of external leads electrically connected to the semiconductor chip and protruding in all directions from the package body; A dam bar formed along the outer edge of the package body to connect between the external lead and the external lead, and preventing the liquid resin from counting outside in the molding process; A connecting bar connecting the end of the outer lead and a sock end connected to the frame; Preparing a lead frame comprising a plurality of curved bars connected to the frame at predetermined intervals from the connection bar in a direction in which the external lead protrudes, and having at least one curved bar; (B) cutting the dambar between the outer leads; (C) cutting the connection bars connecting the outermost outer lead and the frame among the outer leads, and bending the outer leads; (D) plating the surface of the external leads with tin by supplying electricity through a bending bar connecting the frame and the external leads; And (E) cutting the connection bars and tie bars connecting the ends of the external leads to separate the individual semiconductor packages from the lead frame; When bending the external leads in the step (C), the bending bar is extended while the bending bar comes down toward the bending of the external lead, the semiconductor package manufacturing method, characterized in that the external lead attached to the frame. The method of claim 1, wherein in the step (C), the external lead is bent into a hook wing type. The method of claim 1, wherein the curved bar has a L-shape. The method of claim 1, wherein before the step (C) is performed and the step (D) is performed, the step of removing the fresh residue remaining in the external lead in the forming process of the step (A) is performed. A semiconductor package manufacturing method.