JPH0897341A - Manufacture of lead frame for semiconductor device - Google Patents

Abstract

PURPOSE: To provide the manufacture of a highly reliable lead frame by preventing bubble generation between the terminal leads so as to maintain terminal lead alignment accuracy at the time of forming a dam bar using insulating photo-setting solder mask resist on the terminal lead and improving chemical resistance of the resist between the leads. CONSTITUTION: Unnecessary parts are removed from metal conductive strip material so as to allow the leading edges of inner leads 13 to be connected, and the continuous body of lead frames in intermediate shape is provided. A thin layer of solder mask resist is applied to the prescribed parts on the top and bottom planes on the terminal lead 16 of the continuous body, and the resist pattern for a frame-shaped clam bar 18 is formed on the top and bottom face of the resist by exposure. Then, after forming the frame-shaped dam bar by developing and removing the unexposed parts (unhardened parts) by peeling, the terminal lead 16 is processed to have a prescribed length, and the connection at the leading edge of the inner lead 13 is cut. Thus, the lead frame which has the dam bar 18 at the prescribed part on the terminal lead 16 is provided.

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 for a semiconductor device, and more particularly, it connects a plurality of terminal leads to each other and fixes them together and insulates a dam bar for preventing a sealing resin from flowing out. The present invention relates to a method for manufacturing a lead frame for a semiconductor device, which is formed of a photo-curable solder mask resist member.

[0002]

2. Description of the Related Art Conventionally, a semiconductor device (not shown) includes an element mounting portion, a plurality of terminal leads arranged around the element mounting portion, and a plurality of terminal leads which are connected and integrated with each other and sealed. A lead frame provided with an integrated dam bar left unremoved to prevent the resin from flowing out and an outer frame holding these is used.
A semiconductor element mounted and fixed on the element mounting portion of the lead frame, a bonding wire for connecting an electrode pad of the element and one end portion of the terminal lead to form an electrical conduction circuit, and the element mounting portion. , The element, one end of the terminal lead and a package in which the wire is resin-molded, and the other end of the terminal lead and the dam bar are exposed.

However, in this type of semiconductor device,
The resin burr flowing out to the portion surrounded by the terminal leads and the dam bars around the package and the dam bars are removed by using a highly accurate punching die device or a laser device, and the terminal leads are individually separated. It was necessary to separate and independence, therefore, when punching and removing the dam bar, the terminal lead is twisted, deformation such as positional deviation occurs, and as a result, the quality and productivity of the semiconductor device are reduced, There was a problem that it was not possible to respond quickly to multiple bins such as narrow fine pitch between terminal leads. In order to solve such a problem, a semiconductor device using a lead frame provided with a dam bar having an insulating resin as a constituent member is disclosed.

As an example of a method for manufacturing a lead frame used in this type of semiconductor device, an element mounting portion shown in FIG. 6 is formed by sequentially removing unnecessary portions from a thin metal strip material by a pressing process or an etching process. 61, terminal lead 6
2 and an outer frame 63 for supporting the same, and a step of shaping for preparing a lead frame 60 having a desired shape in which the tips of the inner leads 64 constituting the terminal leads 62 are separated, and the step of forming the shape. The top surface of the lead frame,
A conventional atmospheric pressure lamination process for laminating an insulative photo-curable dry film / solder mask resist (hereinafter referred to as solder mask resist) member on either or both of the lower surface side and the solder mask resist. An exposure step of adhering the pattern mask of the dam bar to form a frame-shaped resist pattern of the dam bar on the upper surface and / or the lower surface of the solder mask resist of the terminal lead, and an unexposed portion that does not polymerize in the step (uncured) Part of the resist is washed off to form the frame body of the dam bar.

[0005]

However, in the above-mentioned manufacturing method of the prior art, since the solder mask resist is laminated under normal pressure, air bubbles as shown in FIG. 7 are formed on the resist bonding interface between the upper surface side and the lower surface side. There was a phenomenon that Q was generated. As a result, when going through the heating process of the subsequent process,
There are problems that the dam bar is peeled off due to the expansion phenomenon of the bubbles Q and impurities such as a cleaning liquid remain in the bubbles Q to reduce the bonding strength.

Further, there is a problem that thermal expansion of the air bubbles Q causes long-term reliability such as generation of cracks in the resin sealing portion of the semiconductor device.

Further, when laminating the solder mask resist on the terminal leads, one end portion of the terminal lead is a separated free end as shown in FIG. 6, so that the space between the terminal leads is filled with resist. When they are connected to each other, there is a problem in that the terminal leads are deformed such as misaligned, and residual stress remains in the constituent members in the joint region.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and in particular solves the above problems that occur when forming a dam bar having the solder mask resist as a member on the terminal lead. Manufacture of a lead frame for a semiconductor device capable of obtaining a lead frame for a semiconductor device with high long-term reliability while maintaining the positional accuracy of the terminal leads and improving the chemical resistance of the resist embedded between the terminal leads. To provide a method.

[0009]

According to the method of manufacturing a lead frame for a semiconductor device according to the first aspect of the present invention, a plurality of terminal leads composed of an inner lead and an outer lead are connected and supported to each other. , A semiconductor device lead using a frame body formed by curing a photocurable dry film solder mask resist (hereinafter referred to as a solder mask resist) made of an insulating member on a dam bar for preventing the sealing resin from flowing out In the method of manufacturing a frame, a binder member is left so that the tips of the internal leads are connected,
Required processing including a process of removing unnecessary portions around it to form the terminal lead and the like and a process of forming a concave groove at a predetermined position on either or both of the upper surface and the lower surface of the terminal lead. A first shape processing step of forming a continuous body of an intermediate-shaped lead frame, and defoaming the solder mask resist between the surface side and the lower surface side of the continuous body formed in the step between the terminal leads. After performing a vacuum lamination step of forming a laminated continuous body, an exposure step of forming a hardened layer of the resist pattern required for the dam bar on the upper surface and the lower surface of the laminated continuous body, and removing an unexposed portion of the solder mask resist. A dam bar frame forming step including a developing step of forming the dam bar;
A second shape processing step of removing the binder member by performing a process of forming the inner lead to a predetermined length.

According to a second aspect of the present invention, there is provided a method for manufacturing a lead frame for a semiconductor device, which is the method for manufacturing a lead frame for a semiconductor device according to the first aspect, wherein copper is used as a conductive metal strip used in the lead frame for the semiconductor device. It is configured to use a system material.

According to a third aspect of the present invention, there is provided a method of manufacturing a lead frame for a semiconductor device, wherein the lead frame for a semiconductor device is manufactured by ultraviolet exposure and curing downstream of the dam bar frame forming step. It is configured to include a treatment step (heat treatment step).

A method for manufacturing a lead frame for a semiconductor device according to a fourth aspect is the method for manufacturing a lead frame for a semiconductor device according to the third aspect, wherein sulfuric acid is provided downstream of the ultraviolet exposure process and the curing process (heat treatment process). It is configured to include a cleaning process and a warm water cleaning process.

[0013]

In the method of manufacturing a lead frame for a semiconductor device according to claim 1, since the end portions of the terminal leads are connected and integrated by a binder member, the terminal leads produced when laminating by the conventional technique. Position deviation is prevented, and at the time of assembling the semiconductor device, a residual stress that causes deformation such as twisting near the terminal leads is prevented.

Further, since the lamination of the solder mask resist is subjected to the vacuum lamination process, the air bubbles Q shown in FIG. To prevent.

Further, in the method of manufacturing a lead frame for a semiconductor device according to a second aspect, since the copper-based material is used as the conductive metal strip of the lead frame, the adhesion of the solder mask resist is improved. .

Further, in the method for manufacturing a lead frame for a semiconductor device according to a third aspect of the present invention, since the ultraviolet exposure and curing process (heat treatment process) is provided downstream of the dam bar frame forming process, The resist in the exposed and unexposed areas of the contour of the dam bar can be sufficiently hardened to significantly improve the bonding strength, and the residual stress that causes the deformation of the terminal leads can be removed. Is improved.

Further, in the method for manufacturing a lead frame for a semiconductor device according to the fourth aspect, since the cleaning step is provided downstream of the step of ultraviolet exposure and curing (heat treatment step), it adheres to the terminal lead or the like. The impurities are completely removed, and the cleanliness of the dam bar is significantly improved.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention having the above structure and operation will be described in detail with reference to the accompanying drawings.

Here, FIG. 1 is a plan view showing an embodiment of a lead frame for a semiconductor device manufactured by the method of the present invention,
2 is a manufacturing process chart showing an embodiment of the method of the present invention, FIG.
Is a plan view of a lead frame for an intermediate shape semiconductor device manufactured by the method of the present invention, FIG. 4 is a schematic explanatory view of a process of vacuum lamination of the present invention, and FIG. 5 is a joined state of a dam bar formed by the method of the present invention. FIG. Less than,
A method for manufacturing a QFP (quat flat package) type lead frame for a semiconductor device, which is an example of the present invention, will be described with reference to FIGS. 1, 2, 3, 4, and 5 attached.

First, as shown in FIG. 1, a lead frame 10 for a semiconductor device formed according to the present invention has an element mounting portion 11 for mounting a semiconductor element in a central portion, and an electrode pad for the semiconductor element (not shown). An external lead 1 having an inner lead 13 having a wire bonding region 12 forming a conductive circuit and a connection terminal 14 forming an external lead-out circuit.
5 and a plurality of terminal leads 16 and the terminal lead 1
6 are provided with concave grooves 17 on the upper and lower surfaces (see FIG. 3),
The solder mask resist R is attached to the member of the dam bar 18 that holds the terminal lead 16 on the upper surface side and the lower surface side of the predetermined area of the terminal lead 16 including the groove 17 and prevents the sealing resin from flowing out. It is configured to be hardened in a frame shape. Here, 19 is an outer frame for connecting the external leads, and 20 is a positioning pilot hole.

In this case, the dam bar 18 is substantially the same as the plate thickness of the terminal lead 16 along the boundary of the resin sealing area so that a part thereof is located in the resin sealing area, or the terminal A frame in which the solder mask resist R is filled and cured between the groove 17 and the terminal lead so that the terminal lead 16 is sandwiched from the upper and lower surfaces of the terminal lead 16 so as to have a thickness that thinly covers the surface of the lead 16. It is formed on the body.

Next, in the method of manufacturing a lead frame for a semiconductor device, which is an example of the embodiment of the present invention shown in FIG. 2, unnecessary portions are removed from the metal conductive strip so that the leading ends of the inner leads 13 are connected, A first shape processing step A for preparing a lead frame continuous body 21 of a required intermediate shape, and the solder mask on the predetermined surface of the terminal lead 16 of the continuous body 21 formed in the step A, on the lower surface side. Vacuum lamination step B for laminating the resist R, exposure step C for forming the resist pattern of the frame-shaped dam bar 18 on the upper and lower surfaces of the solder mask resist R laminated in the step B, and an unexposed portion of the exposure step C (Unhardened part)
The frame body forming step E of the dam bar including a developing step D of forming the frame body of the frame-shaped dam bar 18 by peeling and removing the inner lead 13 and the internal lead 13 And a second shape processing step F for separating the connection of the tips of the. Then, the first shape processing step A, the dam bar frame forming step E, and the second shape processing step F are sequentially performed, and the dam bar 18 having the solder mask resist as a member is connected to the terminal lead 16 It is possible to obtain the semiconductor device lead frame shown in FIG. Next, details of the steps of the above-described method for manufacturing a semiconductor device lead frame will be described.

First, in the first shape processing step A, a photoresist coating step (not shown) and exposure /
By a conventional photo-etching process including a developing step and the like, the continuous strip of the copper-based material is used for the element mounting portion 1 shown in FIG.
1. A plurality of terminal leads 16 each including an inner lead 13 and an outer lead 15, a binder member 22 in which the tips of the inner leads 13 are connected to each other, and an outer frame 19 for connecting the ends of the outer leads 15 are left. While removing the periphery thereof, a continuous body 21 having an intermediate shape of the lead frame shown in FIG. 3 in which concave grooves 17 are provided at the positions where the dam bars 18 are formed on the upper surface and the lower surface of the terminal lead 16 is formed. Is configured.

By adopting such a configuration,
Since the binder member 22 that connects the tip portions of the inner leads 13 is provided and the solder mask resist R is laminated in the next step in a state where the positional accuracy of the terminal leads 16 is accurate, the terminal leads generated in the prior art are generated. It is possible to prevent the positional displacement of 16 so that the mutual positional dimensions of the terminal leads 16 during the lamination can be maintained in a predetermined state.

Further, since the concave groove 17 is provided on the upper surface and the lower surface of the terminal lead 16 at the position where the dam bar 18 is to be formed, the dam bar 18 has the same thickness as the terminal lead. Also, the groove 17 can be filled with the resist to form a state of being connected to the resist between the terminal leads, and the terminal leads 16 can be firmly held, and peeling in the next step can be prevented.

Subsequently, in the dam bar frame forming step E, as shown in FIG. 4, on the upper surface side and the lower surface side of the transfer path in the vacuum chamber 41 and the sub chamber 41a,
Unloading 4 to unroll the solder mask resist R
2, a preheat roll 43, a laminating roll 44, a press roll 45, a vacuum pump 46 and a guide roll 47 are arranged at a predetermined position in a vacuum laminator 40, which is an example of a laminator, and a continuous body 21 formed by the above-described shape processing A. Are continuously conveyed, the solder mask resist R supplied from the unloading 42 is heated by the preheating roll 43, and then the continuous body 2 is moved by the laminating roll 44.
The solder mask resist R from the upper surface side and the lower surface side of FIG.
While the air in the chambers 41, 41a is being discharged by the vacuum pump 46, the air is laminated on a required area of the continuous body 21. Subsequently, the press roller 45 provided downstream of the laminating roll 44 presses the resist, and the resist R is provided between the leads of the terminal lead 11 as shown in FIG.
To form a continuous body 21 filled with and coated with. Next, a mask pattern (not shown) having a required shape of the dam bar 18 is brought into close contact with and exposed at predetermined locations on the upper surface and the lower surface of the continuous body 21 covered with the resist R to form a hardened layer of the resist pattern of the dam bar 18. Form. Then, the unexposed portion of the resist (not shown) is removed to form the frame body of the dam bar 18 to which the terminal leads 16 shown in FIG. 5 are connected.

By adopting such a configuration,
The air bubbles Q (see FIG. 7) generated at the boundary surface of the resist during the prior art lamination are eliminated, and the resist R can completely fill the gap between the terminal leads 16.

Subsequently, in the second shaping step F, the binder member 22 connecting the tips of the internal leads is removed to separate the terminal leads into a predetermined length. Has been done.

The structure of the first shape processing step A, the dam bar frame forming step E, and the second shape processing step F has been described above as the method of manufacturing the semiconductor device lead frame of the present invention. As a second embodiment, a structure in which an ultraviolet exposure step and a curing step (heat treatment step) are provided downstream of the dam bar frame forming step E can be adopted. By adopting such a configuration, the gray portion (semi-cured portion) of the contour of the dam bar 18 formed of the cured layer of the resist R is eliminated, and the chemical resistance of the dam bar 18 can be remarkably improved. In addition, the residual stress remaining in the member due to the processing history can be removed, and the terminal lead 16 can be prevented from being deformed such as warped or twisted.

In addition, as a third embodiment (not shown), a cleaning process of a sulfuric acid bath treatment and a hot water bath treatment may be provided downstream of the ultraviolet exposure process and the curing process.
As a result, a surface treatment step can be provided downstream of the dam bar frame forming step E, which improves workability and also improves the cleanliness of the dam bar 18 and significantly improves the quality.

The surface treatment process such as metal plating may be performed either upstream or downstream of the dam bar frame forming process E.

Although the lead frame in which the element mounting portion is integrally formed is described as the above embodiment, the present invention can be applied to the manufacture of a lead frame in which the element mounting portion is provided separately.

[0033]

As described based on the above embodiments, when the method for manufacturing a lead frame for a semiconductor device according to the present invention is used, the dam bar 18 is formed in a state in which the position dimensions of the terminal leads 16 are set. Therefore, it is possible to provide a lead frame for a semiconductor device with good positional accuracy without deformation of the terminal leads.

Moreover, the generation of air bubbles generated in the prior art is eliminated, and as a result, impurities remain and the cleanliness is improved, and the occurrence of cracks in the resin-sealed portion is reduced, and the long-term reliability is high. A lead frame for a semiconductor device for obtaining a semiconductor device can be provided.

Furthermore, the lead frame for a semiconductor device, which eliminates the need for the step of removing the dam bar 18 after the resin sealing in the prior art, can improve the production efficiency of the semiconductor device assembly and reduce the cost. Can be provided.

[Brief description of drawings]

FIG. 1 is a plan view of an embodiment of a lead frame for a semiconductor device manufactured by the method of the present invention.

FIG. 2 is a manufacturing process chart showing an embodiment of the method of the present invention.

FIG. 3 is a plan view of an intermediate shape lead frame for a semiconductor device manufactured by the method of the present invention.

FIG. 4 is an explanatory diagram showing an outline of a vacuum lamination process of the present invention.

FIG. 5 is a partial cross-sectional view showing a joined state of the dam bar formed by the method of the present invention.

FIG. 6 is a plan view of an intermediate-shaped semiconductor device lead frame manufactured by a conventional method.

FIG. 7 is a partial cross-sectional view showing a joined state of a dam bar formed by a conventional method.

[Explanation of symbols]

10 Lead frame for semiconductor device 11 Element mounting part 12 Wire bonding area part 13 Internal lead 14 Connection terminal part 15 External lead 16 Terminal lead 17 Groove 18 Dam bar 19 Outer frame 20 Positioning pilot hole 21 Continuous body of intermediate lead frame 22 Binder Member 41 Vacuum chamber 41a Sub chamber 42 Unloading 43 Preheating roll 44 Laminating roll 45 Press roll 46 Vacuum pump 47 Guide roll A First shape processing step B Vacuum lamination step C Exposure step D Developing step E Dam bar frame forming step F Second shape processing step R Insulating photocurable dry film solder mask resist

Claims (4)

[Claims] 1. A photocurable dry film comprising an insulating member on a dam bar for connecting and supporting a plurality of terminal leads composed of an inner lead and an outer lead to each other and for preventing the sealing resin from flowing out. In a method of manufacturing a lead frame for a semiconductor device using a frame formed by curing a solder mask resist (hereinafter referred to as a solder mask resist), a binder member is left so that the leading ends of the internal leads are connected, Of a required intermediate shape including processing for removing the unnecessary portion to form the terminal lead and the like and processing for forming a concave groove at a predetermined position on either or both of the upper surface and the lower surface of the terminal lead. A first shape processing step of forming a continuous body of the lead frame; and the solder between the terminal lead and the upper surface side and the lower surface side of the continuous body formed in the step. A vacuum lamination step of forming a laminated continuous body while defoaming the mask resist, an exposure step of forming a hardened layer of the resist pattern required for the dam bar on the upper surface and the lower surface of the laminated continuous body, and the solder mask resist not yet formed. A second shape process for removing the binder member by performing a dam bar frame forming process including a developing process of removing the exposed portion and forming the dam bar, and a process of forming the inner lead to a predetermined length. And a step of manufacturing a lead frame for a semiconductor device. 2. The method for manufacturing a lead frame for a semiconductor device according to claim 1, wherein a copper-based material is used as the conductive metal strip used for the lead frame for a semiconductor device. 3. The manufacturing of a lead frame for a semiconductor device according to claim 1, wherein the step of forming the frame of the dam bar includes a step of ultraviolet exposure and curing (heat treatment step) downstream. Method. 4. The method of manufacturing a lead frame for a semiconductor device according to claim 3, wherein a sulfuric acid cleaning process and a warm water cleaning process are included downstream of the ultraviolet exposure process and the curing process (heat treatment process). Method.