JPH0750765B2 - Lead frame used for semiconductor device - Google Patents

Description

The present invention relates to a lead frame used in a semiconductor device.

[Prior Art] Semiconductor devices using lead frames have been used in various industrial fields, but the demands for quality and accuracy are diversifying with the recent trend of high-mix low-volume production and high pin count. Therefore, in manufacturing the lead frame, it is an important issue for the manufacturer to prepare the production system so as to cope with the rapid increase in demand and the 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 substantially in the center of a lead frame, and the mounting stage 1 is connected to a pair of side rails 2 running in the processing line direction by a support lead 3, respectively. Mounting stage 1
A large number of inner leads 4 are protruded toward the outside at intervals around each other, and these inner leads 4 are connected to the side rails 2 by tie bars 5. Further, a large number of outer leads 6 are formed so as to extend from the tie bars 5 in the line direction to the inner leads 4 inside. On the other hand, at a predetermined position of the side rail 2, there are provided a plurality of pilot holes 7 for alignment used when processing is performed in each processing step. A configuration having such an arrangement of the leads is typical of the conventional lead frame.

In the manufacture of semiconductor devices, various post-treatments are performed after molding the lead frame. As the post-treatment, a plating treatment is applied to the tip portions of the mounting stage 1 and the inner leads 4, or a treatment for fixing the inner leads 4 at a predetermined position between the inner leads 4 and the package line P with a tape or an insulating thermosetting resin. Etc. Then, after such processing, the semiconductor element is mounted on the mounting stage 1, wire bonding is performed to connect the tip of the inner lead 4 with the semiconductor element by wire bonding, and further packaging is performed to mount the semiconductor device. Is completed.

The lead frame itself used in the semiconductor device manufactured through the above-mentioned steps is generally a thin metal plate punched into a strip shape by a press working method, or a strip-shaped lead formed by connecting a single lead frame. Formed on the frame. Further, instead of press working, a method of forming a strip-shaped lead frame by a photo-etching method using a glass mask pattern in which a plurality of rows is formed is also adopted.

FIG. 6 is a plan view showing an etching sheet formed by arranging a plurality of strip-shaped lead frames which are composed of a plurality of lead frames alone.

In the figure, a strip-shaped lead frame base 51 is formed by arranging a plurality of single lead frames 50. Each strip-shaped base 51 is then framed by at least one half-etched connecting tab 52.
It is connected to 53 and the holding frame 54. In addition, each strip base 51
It is needless to say that the side rails formed at 1 are provided with the pilot holes shown in FIG.

After the etching process, the strip-shaped base 51 is obtained by separating from the outer frame 53 and the connecting tab 52 of the holding frame 54. The strip-shaped bases 51 thus obtained are manually stacked, arranged and transported to the next step.

In the next step, the sheets are taken out one by one from the loaded strip-shaped bases 51 by a general conveying means, and are inserted into the pilot holes 7 of the side rails 2 shown in FIG. Make a setup to insert. That is, the pilot hole 7 is used for positioning in the next step, and various kinds of processing are performed by the line. Further, when mounting and mounting the semiconductor element on the mounting stage 1, the pilot hole 7 is used for alignment.

[Problems to be Solved by the Invention]

As described above, in manufacturing a semiconductor device using a lead frame, the pilot hole 7 formed in the side rail 2 is used for alignment in each of various post-processing steps. At the time of this alignment, since the reference pin provided on the line or the processing device is inserted into or removed from the pilot hole 7, damage to the pilot hole 7 becomes a problem. That is, when the reference pin is inserted or removed, the pin is easily caught by the pilot hole 7 and is easily damaged by burrs or deformation around the hole. If the pilot hole 7 used for positioning is damaged in this way, accurate positioning cannot be performed in the assembly process of the semiconductor device for performing wire bonding or the like, resulting in misalignment.

To cope with such a problem, an auxiliary rail 55 is provided outside the side rail 2 as shown in FIG.
A lead frame that can open 56 is proposed.

However, in such a lead frame, a material wider than a predetermined material width is required in order to additionally provide the auxiliary rail 55, and an increase in material cost and manufacturing cost cannot be avoided.

Further, since the strip-shaped bases 51 are laminated as strip-shaped lead frames and are fed one by one to the post-processing line, the work itself and the operation of the line become discontinuous. Therefore, in addition to poor workability, the surface of the lead frame is likely to be scratched or soiled during handling, so deterioration in quality cannot be ignored. In addition, if strip-shaped lead frames are stacked and stocked and sent one by one to the line, two sheets may be stacked and fed due to attachment due to their own weight or entanglement of leads, causing the device to stop. Will cause a decrease in work.

On the other hand, when the strip-shaped lead frame formed by the press working method is used for the entire surface plating process of intermittent transfer, when the strip-shaped lead frame is entirely plated, overlap occurs in a part of the strip-shaped lead frame and double plating is performed. It may be done. For this reason, it is necessary to remove the double-plated portion by post-treatment, which increases the number of steps and affects productivity.

The present invention is to eliminate the drawbacks of the prior art as described above, the positioning can be accurately performed in the post-process such as partial plating and the mounting of semiconductor elements, and the workability and work efficiency are improved. Moreover, it is an object of the present invention to reduce the material cost so that a high quality lead frame can be manufactured.

[Means for Solving the Problems]

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

[Examples] Hereinafter, the features of the present invention will be specifically described with reference to Examples 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. The same members described in the conventional example are designated by common reference numerals, and detailed description thereof will be omitted.

As shown in the figure, a strip-shaped base 51 is formed as a strip-shaped lead frame having four lead frames 50, and a connecting body 10 is provided between these strip-shaped bases 51. This connecting body 10 is a glass mask plate (described later).
Are arranged at one end of a strip-shaped base 51 in which the single unit 50 of the four lead frames is connected, baked and developed to form a resist mask sheet, and then, the strip-shaped base 51 and the strip-shaped base 51 are simultaneously formed by photoetching. Therefore, this connecting body 10 can also perform a positioning function by connecting and integrating the strip-shaped bases 51 to each other and providing the side rail 2 with a hole similar to the pilot hole 7.
It is used as a joint margin for integrating these leadframes with each other during various kinds of post-processing. Further, instead of the pilot hole 7 formed in the side rail 2, an auxiliary pilot hole 11 used for positioning in various processing is formed in the coupling body 10.

FIG. 3 (a) is a plan view of a glass mask pattern used to create a strip-shaped base 51 and a connecting body 10 arranged at one end of the strip-shaped base 51 by photoetching.
FIG. 2B is an enlarged view of a portion surrounded by a circle A in FIG.

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

Further, the resist pattern of the strip-shaped lead frame thus created is put into an etching process to remove unnecessary portions, and as shown in FIG. 1, a continuous body of strip-shaped bases 51 connected through the connecting body 10 is obtained. .

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

In FIG. 1A, the material sheet M of the resist pattern of the lead frame integrated by the connecting body 10 is released from the uncoiler 30, and the surface adjusting step, the etching step, the peeling step and the drying step are performed in the etching device 31. After a while, it is wound up again by the coiler 32. Next, after being transferred from the coiler 32 to the uncoiler 33 ((b) in the same figure), it is sent to the plating device 34 for plating treatment, and then wound again on the coiler 35. Further, as shown in FIG. 4 (c), the material sheet M is fed from the uncoiler 36 to the taping device 3
7. The connection body 10 is sent to the cutting device 38, the connection body 10 is removed by the connection body removing device 39, and the strip base 51 is supplied to the die bonding and wire bonding steps of the semiconductor assembly process. It should be noted that although FIG. 4 illustrates the case where each process is separated, it is needless to say that the present invention can be applied to a continuous process in which each process is connected.

In the above steps, the positioning from the etching step to the connecting body removing device 39 is performed using the auxiliary pilot hole 11 provided in the connecting body 10. That is, conventionally, the pilot holes 7 formed in the side rails 2 are positioned for each step.
Instead of using, the reference sheet (not shown) is inserted into or withdrawn from the auxiliary pilot hole 11 to position the material sheet M in the processing device. When the connector 10 is removed by the connector removing device 39, four lead frame units U are supplied to the die bonding device 39 and the wire bonding device 40 downstream, as shown in FIG. At this time, the positioning of each unit U with respect to the processing apparatus utilizes the remaining pilot hole 7 of the side rail 2.

As described above, when manufacturing the lead frame, the auxiliary pilot hole 11 provided in the coupling body 10 is used for positioning from the etching process to the plating process and the taping process for the post-process. In addition, positioning such as die bonding and wire bonding, which requires highly accurate positioning after these processes, is performed by the pilot hole 7 of the side rail 2. Therefore, the damage of the pilot hole 7 is reduced as compared with the conventional method in which the same pilot hole 7 is used from the beginning to the end of line production.
Therefore, in the process of die bonding or wire bonding, the pilot hole 7 can be used in a state where the pilot hole 7 is not deformed or the inner diameter is not increased, and the processing can be performed with high accuracy. Further, compared with the case where the auxiliary rail 55 and the like described in FIG. 7 are attached, the material is not wasted and the cost is not affected.

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

Further, since the lead frame can be sent to the line in strip form by the connecting body 10, the productivity is much higher than the conventional case where strip-shaped lead frames are supplied one by one. Further, there is no obstacle such as double feeding of the two strip-shaped lead frames, and it is possible to prevent a decrease in operating rate due to line stop.

Further, in the case where the strip-shaped lead frame is intermittently conveyed and subjected to the plating treatment, the plating layers are likely to be doubled due to the positional relationship between the preceding lead frame and the subsequent lead frame. On the other hand, the strip-shaped lead frame can be continuously supplied to the line like a strip by the connecting body 10, the plating does not overlap, and the conventional steps such as peeling removal are not required.

Further, the processes from the photo etching process to the die bonding of the semiconductor assembly structure can be connected and processed, and the intermediate coiler, uncoiler and the like can be removed, and the effect of simplifying the semiconductor device manufacturing line can be expected.

〔The invention's effect〕

As described above, in the present invention, the strip-shaped base is integrated by the connecting body to form a strip shape, and the auxiliary pilot hole is provided in the connecting body in addition to the pilot hole provided in the side rail. Therefore, the auxiliary pilot holes and the pilot holes provided in the side rails can be used when positioning the processing device or the like for many processes. Therefore, compared with the conventional structure that uses only the pilot hole, the auxiliary pilot hole prevents deformation and distortion of the pilot hole near the lead frame, and achieves high positioning accuracy and leads. High quality products can be obtained without bending or twisting the frame.

Furthermore, since a plurality of strip-shaped frames can be connected in a strip shape by the connecting body, processing can be performed by a continuous or intermittent transfer line. Therefore, the productivity is significantly improved as compared with the conventional method in which the strip-shaped bases are fed to the line one by one.

[Brief description of drawings]

FIG. 1 is a plan view of a lead frame of the present invention, FIG. 2 is an enlarged plan view of essential parts, and 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 view showing processing steps from etching of the lead frame to wire bonding by an apparatus, FIG. 5 is a plan view of a conventional general lead frame, and FIG. 6 is a plan view showing an etching sheet of a strip lead frame. FIG. 7 is a plan view showing a conventional example of a lead frame provided with an auxiliary rail. 1: Mounting stage, 2: Side rail 3: Support lead, 4: Inner lead 5: Tie bar, 6: Outer lead 7: Pilot hole 10: Connected body, 11: Auxiliary pilot hole 20: Glass mask plate 21: Lead frame pattern 22: Connected pattern 30, 33, 36: Uncoiler 31, Etching device, 32, 35: Coiler 34: Plating device, 37: Taping device 38: Connected object removing device 39: Die bonding device 40: Wire bonding device 50: ( (Lead frame) Single unit 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 belt-shaped base having a plurality of single lead frames formed in series between a pair of side rails having positioning pilot rods is arranged on a glass mask plate surface in a plurality of rows, and is formed by photoetching. In the lead frame, a connecting body is formed at one end of the strip base, and the other end of the other strip base is connected by the connecting body to form a strip, and an auxiliary pilot hole for positioning is provided in the connecting body. A lead frame used in a semiconductor device characterized by the above.