JP3013135B2 - Method for manufacturing lead frame for semiconductor device - Google Patents

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 for a semiconductor device, and more particularly, to a method for connecting and fixing a plurality of terminal leads to each other and insulating a dam bar for preventing leakage of a sealing resin. The present invention relates to a method for manufacturing a lead frame for a semiconductor device formed of a light-curable solder mask resist member.

[0002]

2. Description of the Related Art Conventionally, a semiconductor device (not shown) has an element mounting portion, a plurality of terminal leads arranged around the element mounting portion so as to surround the element mounting portion, and the terminal leads are interconnected and integrated with each other and sealed. A lead frame provided with an integral dam bar and an outer frame that holds them and is left out so as to prevent resin from flowing out 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 to one end of the terminal lead to form an electrical conduction circuit; And a package formed by resin-molding the element, one end of the terminal lead and the wire, and the other end of the terminal lead and the dam bar are exposed.

However, in this type of semiconductor device,
The resin burrs and the dam bar that flowed out to the portion surrounded by the terminal lead and the dam bar around the package are removed using a high-precision punching die device or a laser device, and the terminal leads are individually removed. It was necessary to separate and independent, therefore, when punching and removing the dam bar, torsion in the terminal lead, deformation such as misalignment occurs, and as a result, the quality and productivity of the semiconductor device is reduced, There is a problem that it is not possible to immediately respond to the increase in the number of bins such as a fine pitch between terminal leads. In order to solve such a problem, a semiconductor device using a lead frame provided with a dam bar made of an insulating resin is disclosed.

As an example of a method of manufacturing a lead frame used in this type of semiconductor device, an unnecessary portion is sequentially removed from a thin metal plate material by a press working or an etching working method, and an element mounting portion shown in FIG. 61, terminal lead 6
2, and an outer frame 63 for supporting the lead, and a shape processing step of preparing a lead frame 60 having a required shape in which the distal ends of the internal leads 64 constituting the terminal leads 62 are separated, and Upper surface of the lead frame,
A conventional normal pressure lamination process of laminating an insulative photocurable dry film solder mask resist (hereinafter referred to as a solder mask resist) member on one or both of the lower surface sides, and on the solder mask resist An exposure step of forming a frame-shaped resist pattern of the dam bar on an upper surface and / or a lower surface of the solder mask resist of the terminal lead by closely adhering the pattern mask of the dam bar; Part), the resist is washed off to form a frame of the dam bar.

[0005]

However, in the above-described conventional manufacturing method, since the solder mask resist is laminated at normal pressure, bubbles such as shown in FIG. Q occurred. As a result, when going through the post-heating step,
There have been problems such as peeling of the dam bar due to the expansion phenomenon of the bubble Q and reduction of bonding strength due to impurities such as a cleaning solution remaining in the bubble Q.

Furthermore, there has been a problem that the thermal expansion of the air bubbles Q causes a crack in the resin sealing portion of the semiconductor device, thereby deteriorating long-term reliability.

When laminating the solder mask resist on the terminal leads, since one end of the terminal lead is a free end separated as shown in FIG. 6, the space between the terminal leads is filled with a resist. When connecting with each other, there is a problem that deformation such as displacement of the terminal leads occurs, and that residual stress is retained 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, has been made to solve the above-mentioned problems that occur when forming a dam bar using the solder mask resist as a member on the terminal lead. Manufacture of a semiconductor device lead frame capable of maintaining the positional accuracy of the terminal leads, improving the chemical resistance of the resist embedded in the space between the terminal leads, and obtaining a long-term reliable semiconductor device lead frame. It is to provide a method.

[0009]

According to a first aspect of the present invention, there is provided a method for manufacturing a lead frame for a semiconductor device, the method comprising: connecting and supporting a plurality of terminal leads each including an internal lead and an external lead; A lead for a semiconductor device using a frame formed by curing a photocurable dry film solder mask resist (hereinafter, referred to as a solder mask resist) made of an insulating material on a dam bar for preventing leakage of a sealing resin. In the method of manufacturing a frame, leaving a binder member so that the tip of the internal lead is connected,
A required process including a process of forming the terminal lead and the like by removing unnecessary portions around the same and a process of forming a concave groove at a predetermined position on one or both of an upper surface and a 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 terminal leads from the shape surface side and the lower surface side of the continuous body formed in the step. Performing a vacuum lamination step of forming a laminated continuum, an exposure step of forming a cured layer of the resist pattern required for the dam bar on the upper and lower surfaces of the laminated continuum, and removing an unexposed portion of the solder mask resist A frame forming step of the dam bar including a developing step of forming the dam bar,
A second shape processing step of removing the binder member by performing processing for forming the internal lead to a predetermined length.

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

According to a third aspect of the present invention, there is provided a method of manufacturing a lead frame for a semiconductor device according to the first and second aspects, wherein the step of forming a frame of the dam bar is performed by exposing and curing with ultraviolet light. It is configured to include a processing step (heat treatment step).

According to a fourth aspect of the present invention, there is provided a method of manufacturing a lead frame for a semiconductor device according to the third aspect of the present invention, 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 hot water cleaning process.

[0013]

In the method for manufacturing a lead frame for a semiconductor device according to the first aspect, the terminal leads are formed by laminating according to the prior art because the tip ends of the terminal leads are connected by a binder member and integrated. And the occurrence of residual stress that causes deformation such as twisting due to the terminal leads when assembling the semiconductor device.

Further, since the lamination of the solder mask resist is performed by vacuum lamination, the generation of bubbles Q shown in FIG. To prevent.

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

In the method of manufacturing a lead frame for a semiconductor device according to a third aspect of the present invention, an ultraviolet exposure and curing process (heat treatment process) is provided downstream of the dam bar frame forming process. The resist in the gray portion of the exposed portion and the unexposed portion of the contour of the dam bar can be sufficiently cured to significantly improve the bonding strength, and to remove the residual stress which causes the deformation of the terminal lead. Further, the chemical resistance of the dam bar Is improved.

In the method for manufacturing a lead frame for a semiconductor device according to the fourth aspect of the present invention, the cleaning step is provided downstream of the step of ultraviolet light exposure and curing (heat treatment), so that it adheres to the terminal leads and the like. The impurities are completely removed and the cleanliness of the dam bar is significantly improved.

[0018]

Next, an embodiment of the present invention having the above configuration and operation will be described in detail with reference to the accompanying drawings.

FIG. 1 is a plan view showing one embodiment of a lead frame for a semiconductor device manufactured by the method of the present invention.
FIG. 2 is a manufacturing process diagram showing one embodiment of the method of the present invention.
Is a plan view of a lead frame for a semiconductor device having an intermediate shape manufactured by the method of the present invention, FIG. 4 is a schematic explanatory view of a vacuum lamination process 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 lead frame for a semiconductor device of a QFP (Quat Flat Package) type, which is an example of the present invention, will be described with reference to FIGS. 1, 2, 3, 4 and 5.

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 (not shown) of the semiconductor element. An internal lead 13 having a wire bonding region 12 forming a conductive circuit and an external lead 1 having a connection terminal 14 forming an external lead-out circuit
5 and a plurality of terminal leads 16
6, concave grooves 17 are provided on the upper and lower surfaces (see FIG. 3),
The solder mask resist R is applied to a member of a dam bar 18 for connecting and holding the terminal lead 16 on the upper surface side and the lower surface side of a predetermined region of the terminal lead 16 including the groove 17 and for preventing the sealing resin from flowing out. It is configured to be provided by being cured in a frame shape. Here, 19 is an outer frame for connecting external leads, and 20 is a positioning pilot hole.

In this case, the dam bar 18 is substantially equal in thickness to the terminal lead 16 along the boundary of the resin sealing region so that a part thereof is located in the resin sealing region, or A frame formed by filling and curing the solder mask resist R between the groove 17 and the terminal lead so as to sandwich the terminal lead 16 from above and below the terminal lead 16 so as to have a thickness that covers the surface of the lead 16 thinly. It is formed on the body.

Subsequently, in the method of manufacturing a lead frame for a semiconductor device according to an embodiment of the present invention shown in FIG. 2, an unnecessary portion is removed from the metal conductive strip so that the tip of the internal lead 13 is connected. A first shape processing step A for preparing a continuous body 21 of a lead frame having a required intermediate shape; and a solder mask on predetermined and lower surfaces of the terminal leads 16 of the continuous body 21 formed in the step A. A vacuum lamination process B for laminating a resist R, an exposure process C for forming a resist pattern of a frame-shaped dam bar 18 on the upper and lower surfaces of the solder mask resist R laminated in the process B, and an unexposed portion of the exposure process C (Uncured part)
And a developing step D of forming a frame of the frame-shaped dam bar 18 by stripping and removing the internal lead 13 by forming the terminal lead 16 to a predetermined length. And a second shape processing step F for separating the connection of the tips of the two. Then, the first shaping step A, the frame forming step E of the dam bar, and the second shaping 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. The semiconductor device lead frame shown in FIG. 1 provided at a predetermined location can be obtained. Subsequently, the details of the steps of the above-described method for manufacturing a lead frame for a semiconductor device will be described.

First, in the first shape processing step A, a photoresist coating step (not shown)
The element mounting part 1 shown in FIG.
1. A plurality of terminal leads 16 including an inner lead 13 and an outer lead 15, a binder member 22 connecting the tips of the inner leads 13 to each other, an outer frame 19 connecting the ends of the outer leads 15, and the like. In addition to removing the periphery thereof, a continuous body 21 of an intermediate shape of the lead frame shown in FIG. 3 having concave grooves 17 provided at the upper and lower surfaces of the terminal leads 16 at the positions where the dam bars 18 are formed is formed. Is configured.

By adopting such a configuration,
A binder member 22 for connecting the tip of the internal lead 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 lead 16 is maintained. It is possible to prevent the position of the terminal leads 16 from being shifted, whereby 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 at a position where the dam bar 18 is to be formed on the upper surface and the lower surface of the terminal lead 16, the dam bar 18 has the same thickness as the terminal lead. Also, the groove 17 is filled with the resist, and a state in which the groove 17 is connected to the resist between the terminal leads can be formed, so that the terminal leads 16 are firmly sandwiched and peeling in the next step can be prevented.

Subsequently, in the dam bar frame forming step E, as shown in FIG. 4, the upper and lower sides of the transfer path in the vacuum chamber 41 and the sub-chamber 41a are
Unloading 4 for unwinding solder mask resist R
2. A continuum 21 formed by the shape processing A is provided on a vacuum laminator 40 which is an example of a laminator in which a preheating roll 43, a laminating roll 44, a press roll 45, a vacuum pump 46, and a guide roll 47 are arranged at predetermined positions. Is continuously conveyed, and the solder mask resist R supplied from the unloading 42 is heated by the preheating roll 43, and then the continuous body 2 is laminated by the laminating roll 44.
1 from above and from below.
Is laminated on a required area of the continuous body 21 while the air in the chambers 41 and 41a is exhausted by the vacuum pump 46. Subsequently, pressure is applied by the press roller 45 provided downstream of the laminating roll 44, and the resist R is applied between the leads of the terminal leads 11 as shown in FIG.
Is formed. Next, a mask pattern of a required shape of the dam bar 18 (not shown) is brought into close contact with a predetermined portion of an upper surface and a lower surface of the continuum 21 covered with the resist R and exposed to form a cured layer of the resist pattern of the dam bar 18. Form. Thereafter, the unexposed portion of the resist (not shown) is removed to form a frame of the dam bar 18 to which the terminal leads 16 are connected as shown in FIG.

By adopting such a configuration,
Bubbles Q (see FIG. 7) generated at the interface of the resist during lamination of the prior art are not generated, and the space between the terminal leads 16 can be completely filled with the resist R.

Subsequently, in the second shape processing step F, the terminal lead is separated and formed to a predetermined length by removing the binder member 22 connected to the tip of the internal lead. Have been.

As described above, as the method of manufacturing a lead frame for a semiconductor device according to the present invention, the configurations of the first shaping step A, the dam bar frame forming step E, and the second shaping step F have been described. As a second embodiment, an ultraviolet exposure step and a curing step (heat treatment step) can be provided downstream of the dam bar frame forming step E. By adopting such a configuration, the gray portion (semi-cured portion) of the contour of the dam bar 18 formed by the cured layer of the resist R is eliminated, and the chemical resistance of the dam bar 18 can be significantly improved. At the same time, the residual stress remaining in the member is removed by the processing history, so that the terminal lead 16 can be prevented from being deformed such as warping or twisting.

As a third embodiment (not shown), a cleaning step of a sulfuric acid bath treatment and a hot water bath treatment may be provided downstream of the ultraviolet exposure step and the curing step.
As a result, a surface treatment step can be provided downstream of the dam bar frame forming step E, thereby improving workability and improving the cleanness of the dam bar 18 and significantly improving the quality.

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

Although the above embodiment has been described with reference to a lead frame in which an element mounting portion is integrally formed, 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 with reference to the above embodiment, when the method of 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 terminal lead 16 is positioned and dimensioned. Therefore, it is possible to provide a lead frame for a semiconductor device with good positional accuracy without deformation of the terminal leads.

In addition, the generation of air bubbles which occurs in the prior art is eliminated, and as a result, there is no impurity remaining, the cleanliness is improved, and the occurrence of cracks in the resin-encapsulated portion is reduced, so that long-term reliability is high. A lead frame for a semiconductor device for obtaining a semiconductor device can be provided.

Further, the need for the step of removing the dam bar 18 which has been performed after resin sealing in the prior art is eliminated, thereby improving the production efficiency of semiconductor device assembly and reducing costs. Can be provided.

[Brief description of the drawings]

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

FIG. 2 is a manufacturing process diagram showing one embodiment of the method of the present invention.

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

FIG. 4 is an explanatory view 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 a dam bar formed by the method of the present invention.

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

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

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Lead frame for semiconductor devices 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 Intermediate lead frame continuous body 22 Binder Member 41 Vacuum chamber 41a Subchamber 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 Development step E Dam bar frame forming step F Second shape processing step R Insulating light-curing dry film / solder mask resist

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-305552 (JP, A) JP-A-5-21695 (JP, A) JP-A-5-121618 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01L 23/50

Claims (4)

(57) [Claims] 1. A light-curing dry film comprising an insulating member on a dam bar for interconnecting and supporting a plurality of terminal leads formed of an internal lead and an external lead, and for preventing leakage of a sealing resin. 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 a tip portion of the internal lead is connected, and a peripheral member is formed. A required intermediate shape including a process of forming the terminal lead and the like by removing an unnecessary portion and a process of forming a concave groove at one or both predetermined positions of the upper surface and the lower surface of the terminal lead. A first shape processing step of forming a continuous body of a lead frame; and the solder between the terminal leads from an upper surface side and a lower surface side of the continuous body formed in the step. A vacuum lamination step of forming a laminated continuum 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 and lower surfaces of the laminated continuum, A dam bar frame forming step including a developing step of removing the exposed portion to form the dam bar, and a second shape processing of removing the binder member by performing a process of forming the internal lead to a predetermined length. And a method for 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 material used for the lead frame for the semiconductor device. 3. The manufacturing of a lead frame for a semiconductor device according to claim 1, further comprising an ultraviolet exposure and curing step (heat treatment step) downstream of the dam bar frame forming step. Method. 4. The manufacturing of a lead frame for a semiconductor device according to claim 3, further comprising a sulfuric acid cleaning process and a hot water cleaning process downstream of the ultraviolet exposure process and the curing process (heat treatment process). Method.