JPH038364A - Lead frame for semiconductor device - Google Patents

Abstract

PURPOSE:To precisely position a lead frame at the time of manufacture by connecting one end of a band-like base to one end of another band-like base to form a strip of lead frames using a connecting member which is attached to the end of each base and provided with an auxiliary pilot hole for positioning. CONSTITUTION:A band-like base 51 having four simple lead frames 50 and being similar to a strip of fancy paper is formed and an engaging body 10 is provided between the band-like bases 512. The engaging body 10 is arranged at one end of the band-like base 51 which is comprised of the four connected simple lead frames 5 arranged on a glass mask plate, and the resist mask sheet thereof is formed by printing and development. Thereafter the engaging body 10 is formed together with the band-like bases 51 by photo-etching processing method. An auxiliary pilot hole 11 used for the alignment in various kinds of processings instead of a pilot hole 7 provided in a side rail 2 is provided in the engaging body 10. Thus, alignments in the case of an after-process after partial plating, a packaging of semiconductor elements and the like can be performed precisely.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lead frame used in a semiconductor device.

[Conventional technology]

Semiconductor devices using lead frames are used in various industrial fields, but with the recent trend toward high-mix, low-volume production and multi-bin production, requirements for quality and accuracy have also diversified. Therefore, when manufacturing lead frames, it is an important issue for manufacturers to prepare their production systems so that they can respond to the rapid increase in demand and rapid technological innovation.

FIG. 5 shows a plan view of a lead frame for a general semiconductor device.

In the figure, a mounting stage 1 for a semiconductor element is formed approximately in the center of the lead frame, and the mounting stage 1 is connected to a pair of side rails 2 running in the processing line direction by support leads 3, respectively. Loading stage 1
Around the periphery, a large number of inner leads 4 are protruded outward at intervals, and these inner leads 4 are connected to the side rail 2 by tie bars 5. Further, a large number of outer leads 6 are formed so as to be connected to the inner leads 4 on the inside in the line direction from the tie bar 5. On the other hand, the side rail 2 has a plurality of pilot holes 7 at predetermined positions for positioning used when processing in each processing step. A structure having such a lead arrangement is typical of a conventional lead frame.

In the manufacture of semiconductor devices, various post-processing processes are performed after molding a lead frame. This post-processing includes plating the mounting stage l and the tips of the inner leads 4, and fixing the inner leads 4 at a predetermined position between the inner leads 4 and the package line P with tape or insulating thermosetting resin. etc. After such processing, the semiconductor element is mounted on the mounting stage 1, wire bonding is performed to connect the semiconductor element and the tip of the inner lead 4 with a noble metal wire, and the semiconductor device is further packaged by public packaging. is completed.

The lead frame itself used in the semiconductor device manufactured through the above process is generally made by punching a thin metal plate into a rectangular shape using a press processing method, or by forming a band-shaped lead by connecting individual lead frames. formed into a frame. Furthermore, instead of press working, a method of forming by photo-etching using a glass mask pattern in which multiple rows of strip-shaped lead frames are formed has also been adopted.

FIG. 6 is a plan view showing an etching sheet formed by arranging a plurality of strip-shaped lead frames each consisting of a plurality of single lead frames.

In the figure, a strip base 51 of a strip-shaped lead frame is formed by arranging a plurality of single lead frames 50. Each strip base 51 is
At least one half-etched connecting tab 52 connects the outer frame 53 and the retaining frame 54. It goes without saying that the side rails formed on each strip base 51 are provided with pilot holes as shown in FIG.

After the etching process, the strip base 51 is obtained separated from the outer frame 53 and the connecting tab 52 of the holding frame 54.

The band-shaped bases 51 thus obtained are stacked and arranged manually and transported to the next process.

In the next process, the loaded strip bases 51 are taken out one by one by a general conveying means, and a reference pin attached to the device for the next process is inserted into the pilot hole 7 of the side rail 2 shown in FIG. Make arrangements to insert. That is, the pilot hole 7 is used for positioning for the next process, and various processes are performed on the line. Also, when mounting a semiconductor element on the mounting stage 1, positioning is performed using the pilot hole 7.

[Problem to be solved by the invention]

In this way, in the manufacture of semiconductor devices using lead frames, the pilot holes 7 formed in the side rails 2 are used for positioning in each of the various post-processing steps. During this positioning, a reference pin provided on a line or processing device is inserted into or removed from the pilot hole 7, so damage to the biloft hole 7 becomes a problem. That is, when the reference pin is inserted or removed, the pin gets caught in the pilot hole 7 and is susceptible to damage such as formation of cracks or deformation around the hole. If a problem occurs in the pilot hole 7 used for positioning as described above, accurate positioning will not be possible during the assembly process of the semiconductor device in which wire bonding or the like is performed, resulting in misalignment.

To solve this problem, a lead frame has been proposed in which an auxiliary rail 55 is provided on the outside of the side rail 2 and a pilot hole 56 is formed in the auxiliary rail 55, as shown in FIG.

However, in such a lead frame, in order to provide the extra auxiliary rail 55, a material wider than the predetermined material width is required, and an increase in material cost and manufacturing cost is unavoidable.

Further, since the strip bases 51 are stacked as strip-shaped lead frames and are fed one by one to the post-processing line, the work itself and the line operation become discontinuous. This results in poor workability and scratches on the surface of the lead frame during handling.

Since stains and the like are likely to occur, deterioration in quality cannot be ignored. Furthermore, if strip-shaped lead frames are stacked and stocked and fed into the line one by one, the leads may stick together due to their own weight, or the leads may get entangled, resulting in two sheets being fed in duplicate, which can cause the equipment to stop. This results in decreased work.

On the other hand, when a band-shaped lead frame formed by a press processing method is used in a full-surface plating process with intermittent conveyance, a portion of the band-shaped lead frame overlaps when the entire surface is plated, resulting in double plating. Sometimes it is done. Therefore, it is necessary to peel off and remove this double plating part in post-processing, which increases the number of steps and affects productivity.

The present invention solves the above-mentioned drawbacks of the conventional technology, and enables accurate alignment during post-processes such as partial plating and mounting of semiconductor elements, and improves workability and efficiency. Furthermore, the purpose is to reduce material costs and to be able to manufacture high-quality lead frames.

[Means to solve the problem]

In order to achieve the above object, the present invention arranges on a glass mask plate surface a plurality of rows of strip-shaped bases each having a plurality of lead frames formed in series between a pair of side rails having pilot holes for positioning. , a lead frame created by photo-etching, in which a connecting body is formed at one end of the band-shaped base, the other end of the other band-shaped base is connected by the connecting body to form a strip shape, and the connecting body is further connected to the other end of the band-shaped base. It is characterized by having an auxiliary pilot hole for positioning.

〔Example〕

Hereinafter, features of the present invention will be specifically explained with reference to embodiments shown in the drawings.

FIG. 1 is a plan view of a lead frame of the present invention, and FIG. 2 is a plan view showing an enlarged main part. Note that the same members as described in the conventional example will be indicated by common reference numerals, and detailed explanation thereof will be omitted.

As shown in the figure, a strip base 51 is formed as a strip-shaped lead frame having four individual lead frames 50, and a connecting body 10 is provided between these strip bases 51. This connected body IO is arranged on one end of a band-shaped base 51 in which, for example, four individual lead frames 50 arranged on a glass mask plate (described later) are connected, and is baked and developed to form a resist mask sheet, and then a resist mask sheet is formed. It is molded simultaneously with the band-shaped base 51 by an etching process. Therefore, this connecting body 10 has a strip base 51
In addition to connecting and fixing the lead frames together, if the side rail 2 has a hole similar to the pilot hole 7, it can also perform a positioning function, and these lead frames can be integrated together during various post-processing processes. It is used as a bonding allowance. In place of the pilot hole 7 formed in the side rail 2, an auxiliary pilot hole 11 is formed in the connecting body 10 to be used for positioning during various machining operations.

FIG. 3(a) is a plan view of a glass mask pattern used to create the strip base 51 and the connecting body 10 disposed at one end of the strip base 51 by photoetching, and FIG. It is an enlarged view of the part surrounded by circle A in the middle.

As shown in the figure, a lead frame pattern 21 of a lead frame to be molded is placed on a glass mask plate 20.
and a connector pattern 22 for the connector 10. One glass mask pattern 20 is provided with three rows of lead frame patterns 21 and connector patterns 22. By intermittently conveying the strip-shaped thin metal plate material between the upper and lower glass mask patterns having such a pattern by a predetermined feed amount and exposing it, four pieces of material are printed on each side of the strip-shaped thin metal plate material. A resist pattern of an IJ + frame is created, which includes a strip base having a single lead frame and a connecting body 10 at one end of each of these strip bases. By intermittently performing processing using such a method, the connected body 10
A resist pattern of a band-shaped lead frame is created in which the band-shaped bases 51 are connected to each other via.

Furthermore, the created strip-shaped resist pattern of the lead frame is put into an etching process to remove unnecessary parts, thereby obtaining a continuous body of strip-shaped bases 51 connected via the coupling body 10 as shown in FIG. .

FIG. 4 is a schematic diagram showing an example in which the lead frame of the present invention is applied from an etching process to a wire bonding process of semiconductor assembly.

In the same figure (a), the material sheet M of the resist pattern of the lead frame integrated by the connecting body 10 is
It is uncoiled from the uncoiler 30, undergoes a surface preparation process, an etching process, a peeling process, and a drying process in the etching device 31, and then is wound up again by the coiler 32. Next, after transferring from the coiler 32 to the uncoiler 33 (FIG. (b)
), is sent to the plating device 34, is plated, and is wound up again by the coiler 35. Furthermore, Fig. 4 (C
), the material route M is transferred from the uncoiler 36 to the taping device 37. The connecting body 1O is fed into the cutting device 38, removed by the connecting body removing device 39, and becomes a strip base 51, which is then supplied to the wire bonding and wire bonding processes of the semiconductor assembly process. In addition, in FIG. 4, each process is explained separately, but it goes without saying that it can also be applied to a continuous process in which each process is connected.

In the above process, from the etching process to the connecting body removal device 39, the auxiliary pilot hole 1 provided in the connecting body 10 is
Positioning is performed using 1. That is, instead of conventionally using the pilot hole 7 drilled in the side rail 2 for positioning in each process, the auxiliary pilot hole 1 is used for positioning in each process.
The material sheet M is positioned in the processing device by inserting or removing a reference pin (not shown) into or out of the material sheet M. Then, the connector IO is removed by the connector removing device 39.
is removed, the four lead frame units (U) are transferred to the downstream Gui bonding device 39 as shown in FIG.
and wire bonding equipment [40].

At this time, the pilot holes 7 of the remaining side rails 2 are used to position each unit U with respect to the processing device.

As mentioned above, when manufacturing a lead frame, from etching to plating and taping for post-processing, the auxiliary pilot hole IT
is used for positioning.

Further, positioning of wire bonding, wire bonding, etc. that requires highly accurate positioning after these processes is performed using the pilot hole 7 of the side rail 2.

Therefore, compared to the conventional method in which the same pilot hole 7 is used from the beginning to the end of line production, damage to the pilot hole 7 is reduced. Therefore, in the processing of wire bonding and wire bonding, the pilot hole 7 can be used in a state where it is not deformed or its inner diameter is enlarged, and processing can be performed with high precision. Moreover, compared to the case where the auxiliary rail 55 etc. as explained in FIG. 7 are attached, materials are not wasted and costs are not affected.

Furthermore, if a reference pin or the like is frequently attached and detached from the pilot hole 7 of the side rail 2 near the main part of the lead frame, not only the pilot hole 7 portion but also the outer lead 6 and inner lead 4 may be deformed. There is. On the other hand, by using the auxiliary pilot hole 11 of the connecting body 10 that is located away from the main part of the lead frame, deformation such as bending or twisting of the entire lead frame can be suppressed, and the quality is significantly improved.

Furthermore, since the lead frame can be fed into the line in the form of a strip using the connecting body 1O, productivity is much higher than in the conventional method where strip-shaped lead frames are fed one by one. Furthermore, there is no obstacle such as electrical transmission between the two strip-shaped lead frames, and a drop in operating rate due to line stoppage is also prevented.

Furthermore, in the case where strip-shaped lead frames are plated by being produced intermittently, the plating layer tends to be doubled depending on the positional relationship between the preceding lead frame and the following lead frame. On the other hand, the connecting body 10 allows the rectangular lead frame to be continuously supplied to the line like a strip, without causing overlapping of plating, and without any process such as peeling and removal as in the conventional method.

Furthermore, the processes from the photo-etching process to the guide bonding of the semiconductor assembly structure can be processed in a connected manner, and intermediate coilers, uncoilers, etc. can be eliminated, and effects such as the simplification of the semiconductor device manufacturing line can be expected.

〔Effect of the invention〕

As explained above, in the present invention, the band-shaped base is integrated with the connecting body to form a strip shape, and the connecting body is further provided with auxiliary pilot holes in addition to the pilot holes provided in the side rails. Therefore, when positioning in processing equipment etc. for a large number of processes, the auxiliary pilot hole and the pilot hole provided in the side rail can be used. Therefore, compared to the conventional structure that uses only the pilot hole, the use of the auxiliary pilot hole suppresses deformation and distortion of the pilot hole located close to the lead frame, achieving high positioning accuracy and High quality products can be obtained without bending or twisting the frame.

Furthermore, since a plurality of belt-shaped frames can be connected in a strip shape by a connecting body, processing can be performed using a continuous or intermittent conveyance line.

Therefore, compared to the conventional method of feeding strip bases one by one into the line, productivity is significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a plan view of the lead frame of the present invention, FIG. 2 is an enlarged plan view of main parts, FIG. 3(a) is a plan view of a glass mask pattern for molding the lead frame of the present invention, Figure (b) is an enlarged view of the part surrounded by circle A in figure (a),
Fig. 4 is a diagram showing the processing steps from lead frame etching to wire bonding using equipment, Fig. 5 is a plan view of a conventional general +7- lead frame, and Fig. 6 is an etched sheet of a strip-shaped lead frame. A plan view showing,
FIG. 7 is a plan view showing a conventional example of a lead frame provided with auxiliary rails. l: Mounting stage 2: Side rail 3: Support lead 4: Inner lead 5: Tie bar 6: Outer lead 7 pilot hole lO: Connecting body 11: Auxiliary pilot hole 20 Glass mask plate 21: Lead frame pattern 22: Connecting body Patterns 30, 33.36: Uncoiler 31, etching device 32.35: Coiler 34; Plating device 37: Taping device 38: Connecting body removal device 39: Gui bonding device 40: Wire bonding device 50: Single unit (of lead frame) 51 : Strip base 52: Connection tab 53; Outer frame 54: Protective frame 55: Auxiliary rail 56: Pilot hole M: Material sheet U: Unit

Claims (1)

[Claims] 1. A lead frame created by arranging multiple rows of strip bases, each consisting of a series of multiple lead frames formed between a pair of side rails with pilot holes for positioning, on the surface of a glass mask plate, and photo-etching them. A connecting body is formed at one end of the band-shaped base, the other end of the other band-shaped base is connected by the connecting body to form a strip, and an auxiliary pilot hole for positioning is provided in the connecting body. Features Lead frames used in semiconductor devices.