JP2528192B2 - Semiconductor device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a semiconductor device in which an element is mounted on a lead frame and resin-sealed.

[Conventional technology]

A lead frame used for a semiconductor device is formed by etching or pressing a thin metal plate. Then, after the mounting of the element and the wire bonding process, the product is sealed with resin. FIG. 4 shows a schematic vertical sectional view of a typical example of a conventional semiconductor device.

In the figure, the lead frame is mainly composed of a semiconductor element mounting stage 1, a large number of inner leads 2 that surround the semiconductor element and are radially arranged, and outer leads 3 that extend these inner leads 2 toward the outside. Has been done. An insulative resin tape 4 is attached to the upper surface of the inner lead 2 in order to maintain the distance between the respective tip portions facing the mounting stage 1, and a plating layer 5 of a noble metal is further provided on the tip upper surface. ing. On the other hand, the semiconductor element 6 is fixed on the mounting stage 1 by bonding. Then, a wire 7 is bonded between the semiconductor element 6 and the plated layer 5 of the inner lead 2 to form an electric conduction circuit. Further, the entire body except the outer leads 3 is resin-sealed by the resin package 8, and the product is completed.

In such a semiconductor device, the outer lead 3
In order to maintain the required mechanical strength, a thin metal plate of Fe-Ni system, Cu-Fe system or the like having a plate thickness of about 0.25 mm is used as a material. Therefore, the thickness of the inner lead 2 and the mounting stage 1 is about 0.25 mm, which is the same as the material thickness.

[Problems to be Solved by the Invention]

However, the number of lead pins tends to increase to 100 to 200 due to diversification of functions as the integration degree of the semiconductor element 6 increases. For this reason, the width of the tips of the inner leads 2 is so small that the interval pitch is about 0.1 to 0.135 mm, and the inner leads 2 themselves are easily deformed and interfere with each other. Therefore, the distance from the adjacent lead is very small,
Suppressing such deformation has become an extremely important issue.

For example, it is known that when punching a material having a plate thickness of 0.25 mm by a press, it is preferable to have a relationship of D ≧ T between the lead distance D of the inner lead 2 and the plate thickness T. When the plate thickness T is 0.25 mm, the lead interval is about 0.25 mm, which is a general limit of press working in terms of working accuracy and economical efficiency. On the other hand, in the case of etching, since there is a tendency of isotropic etching, etching progresses in the direction perpendicular to the material surface and at the same time this etching progresses in the lateral direction as well, resulting in an undercut phenomenon. This phenomenon increases with the working depth, and when the corrosion coefficient is F, the depth is D, the opening width is w and the working width is W, the relationship of W−w = 2D / F is satisfied between them. It is already known that it is preferable.

Under these conditions, the inner lead 2 has recently been used.
As a material for forming a lead frame for a semiconductor device requiring a fine tip pattern, a material having a plate thickness of about 0.1 to 0.15 mm is used or a TAB method is used.

However, with the former material having the plate thickness, the mechanical strength of the inner lead 2 and the outer lead 3 and the frame portion forming the outer shell thereof becomes small. Therefore, since the positioning pin fits into the reference pitch hole provided in the frame used for positioning in each process, deformation is likely to occur, and the material itself is easily bent, so handling in each process is complicated. Become. Further, even in the latter TAB method, the overall process is complicated, so that the equipment of the manufacturing apparatus is too expensive, and the problem of a decrease in yield is large.

Therefore, the present invention is to maintain the mechanical strength of a portion that is likely to be deformed during material transportation or positioning in each process on the one hand, and to favorably form the inner lead of a fine pattern on the other hand. The purpose is to do.

[Means for solving the problem]

The present invention provides a lead frame in which patterns of inner leads and outer leads are formed by etching or press working, a semiconductor element electrically connected to the inner lead, and the outer lead including the semiconductor element and the outer lead. A semiconductor device which is protruded to the end and is resin-sealed, and has a shape in which the meat on the upper surface side of the tip of the inner lead is stolen, is thinner than the material of the lead frame, and is inner than the thin portion. A resin sealing region extends to the leads, and each of the inner leads is connected by an insulating material that uses a resin tape or a thermosetting resin layer that cuts through the upper surface of the thin portion and surrounds the semiconductor element. And

[Action]

The top surface of the tip of the inner lead in the area of the resin encapsulation is thinner than the outer lead, the mounting stage of the semiconductor element, and the frame of the lead frame material, so the inner lead tip has a fine pattern. Can be molded with high precision. Further, since the outer leads and the like have the same material thickness as the conventional one, a product in which the mechanical strength of the lead frame is not deteriorated is manufactured. Then, by connecting and fixing the thin inner leads with an insulating resin tape or a layer of thermosetting resin, even if the tips of the inner leads are thin, this can be stabilized, and wire bonding with the semiconductor element can be performed. And so on.

〔Example〕

FIG. 1 is a longitudinal cross-sectional view of a main part of a semiconductor device having a quad flat type (QFP) resin-sealed package showing an embodiment of the present invention, and FIG. 2 is a plan view.

In FIG. 2, the pattern of the lead frame is formed by etching by using a thin metal plate material 20 as a strip and flowing it into a line. The plate thickness of the material 20 is, for example, about 0.25 mm as in the conventional one, and reference pin holes 21 used for positioning in each process are formed at both ends.

The pattern of the lead frame has the mounting stage 1, the inner lead 2 and the outer lead 3 for mounting the semiconductor element 6, as in the conventional example shown in FIG. The outer leads 3 are connected by a dam bar 9, and the mounting stage 1 is supported by a support bar 10.

As is apparent from FIG. 1, the tip portion of the inner lead 2 is thinly formed as a thin portion 2a having a shape in which the meat on the upper surface side is stolen. The thin portion 2a is formed during the etching process of the pattern of the lead frame, and its thickness is about 0.125 mm, which is almost half the thickness 0.25 mm of the material 20. That is, in the pattern of the lead frame, only the tip end portion of the inner lead 2 has the thin portion 2a, and the other mounting stage 1 and the outer lead 3 have the same thickness as the material 20. The range where the thin portion 2a is formed is a portion included in the resin sealing region by the resin package 8 shown by the one-dot chain line A in FIG. 2, for example, the region surrounded by the two-dot chain line B in FIG. is there.

A resin tape 4 is attached to the upper surface of the thin portion 2a, and a plating layer 5 is provided on the upper surface of the tip. The resin tape 4 is attached around the mounting stage 1 so as to connect the thin portions 2a of the many inner leads 2 to each other as shown in FIG. With this resin tape 4, even if the tip portion of the inner lead 2 is the thin portion 2a, it is possible to restrain the postures of each other and suppress the occurrence of twisting, bending, and the like. Therefore, the inner lead 2
The mechanical strength of is maintained at an appropriate value even if its tip is thin. Further, the plating layer 5 is applied only to the wiring area, and the semiconductor element 6 is mounted on the stage 1
Then, the wire 7 is bonded to the semiconductor element 6 for electrical connection.

Note that Au, Ag, Pd or the like is used for the plating layer 5. Further, instead of the resin tape 4, a thermosetting resin layer may be used, and in this case, the thin portions 2a may be connected using a dedicated mold device equipped with a heater.

After the bonding of the wires 7, the area of the alternate long and short dash line A in FIG. Then, the semiconductor device having the vertical cross-sectional structure of FIG. 1 is obtained by sending it to the subsequent step, removing unnecessary portions such as the dam bar 9 and the support bar 10, and further bending the outer lead 3 into a predetermined shape.

In the above configuration, since the tip end portion of the inner lead 2 is the thin portion 2a, it is possible to maintain high machining accuracy of the tip end portion even when the number of leads is large. That is, as compared with the conventional case where a material having the same thickness is processed by etching, press punching or the like, a fine pattern can be easily obtained if the material is thin, so that the processing accuracy is high. Therefore, the wire bonding accuracy of the wire 7 to the semiconductor element 6 is also improved, and the product yield is improved. In particular, since the resin tape 4 is attached to the upper surface of the thin portion 2a so that the positions of the thin portions 2a do not shift from each other, the posture of the tip of the inner lead 2 and the like should be properly maintained, and the thin portion should be thin There is no obstacle.

On the other hand, from the viewpoint of mechanical strength, the material 20 having the same thickness as that of the conventional material is used, and therefore the handling at the time of etching or pressing can be the same as before, and no new manufacturing equipment is required. Especially, since the material 20 has a proper thickness, it is a reference pin hole used for positioning in each process.
Positioning is accurately performed in each process without any positional deviation or deformation of 21. Further, since the resin package 8 is resin-sealed up to the area outside the thin portion 2a, the thin portion 2a is not directly subjected to an external force and is not damaged.

In the above example, the lead frame pattern is formed by etching, and at the same time, the thin portion 2a is formed.
However, the lead frame may be processed by pressing after forming the thin portion 2a by half etching.

FIG. 3 is a longitudinal sectional view of the main part of a semiconductor device showing another embodiment.

In FIG. 3A, the mounting stage 1 is not formed in the pattern of the lead frame, and the semiconductor element 6 is connected to the inner lead 2 by the direct bonding method. The lower surface of the semiconductor element 6 is directly fixed to the plating layer 5 on the upper surface of the thin portion 2a at the tip of the inner lead 2 and electrically connected by the conventional direct bonding method.

Similarly, in FIG. 3 (b), the lower surface of the tip end portion of each inner lead 2 is integrated with one holding tape 11 without forming the mounting stage 1, and the semiconductor element 6 is fixed on the holding tape 11. Further, the wire 7 is used for bonding.

Also in these examples, the thin portion 2a is provided at the tip of the inner lead 2 and the resin tape 4 is attached to the upper surface thereof.
Furthermore, the point that the plating layer 5 is applied to the upper surface of the tip portion is the same as the above example. In addition, it is also the same that the outer leads up to the inner lead 2 including the thin portion 2a are resin-sealed by the resin package 8. It is needless to say that the same working effect as that of the above-described example can be achieved with respect to the improvement of the machining accuracy of the tip of the inner lead 2 and the maintenance of the mechanical strength.

The present invention can be applied to not only the illustrated semiconductor device but also a dual in-line package, a single in-line package and a ceramic package.

〔The invention's effect〕

As described above, in the present invention, only the tip portion of the inner lead is made thin, and even the outer inner lead including this portion is resin-sealed. Therefore, as compared with the case where the tip of the inner lead is processed with the thickness of the material of the lead frame being unchanged, a fine pattern can be processed with high accuracy, and the manufacturing of a product having a large number of leads becomes easy. In addition, the improvement in the accuracy of processing the inner leads also improves the accuracy of wire bonding with the semiconductor element. Particularly, by restraining the inner leads with each other by the resin tape attached to the thin portion, the tips of the inner leads are thin. Also, the positions of the inner leads can be prevented from being displaced from each other, and the processing accuracy is further improved. Therefore, the tips of the inner leads are stabilized, and the yield of wire bonding is significantly improved. Furthermore, since the outer leads and other frame materials have the same thickness as conventional products, handling is easy and the outer leads do not undergo unnecessary deformation, and a semiconductor device superior in terms of quality and reliability is provided. can get.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of an essential part of a semiconductor device of the present invention, FIG. 2 is a schematic plan view showing a pattern of a lead frame, and FIGS. 3 (a) and 3 (b) show different embodiments. FIG. 4 is a schematic vertical sectional view of a main part, and FIG. 4 is a sectional view of a conventional example. 1: Mounting stage 2: Inner lead, 2a: Thin part 3: Outer lead, 4: Resin tape 5: Plating layer, 6: Semiconductor element 7: Wire, 8: Resin package 9: Dam bar, 10: Support bar 11: Hold Tape 20: Material, 21: Reference pin hole

Claims (1)

(57) [Claims] 1. A lead frame in which patterns of inner leads and outer leads are formed by etching or press working, a semiconductor element electrically connected to the inner leads, and the semiconductor element including the semiconductor element and the outer leads being externally provided. A semiconductor device protruding and resin-sealed, wherein the inner lead has a shape in which the top side of the tip of the inner lead is stolen and is thinner than the material of the lead frame, and the inner lead outside the thin portion. Up to a resin sealing region, each of the inner leads are connected by an insulating material that utilizes a resin tape or a thermosetting resin layer that cuts through the upper surface of the thin portion and surrounds the semiconductor element. Semiconductor device.