JP6738676B2 - Lead frame - Google Patents

Description

The disclosed embodiments relate to lead frames.

Conventionally, in a resin-molded (MAP: Molded Array Package) type lead frame, the tip ends of two or more adjacent leads whose base ends are connected to the connecting bar are electrically connected to each other. There is known a technique of providing a connecting portion for connecting (see, for example, Patent Document 1).

JP, 2005-26466, A

However, as the chip size of the semiconductor chip mounted on the die pad is increased, the size of the die pad is also increased, and therefore the distance between the connecting bar and the connecting portion is narrowed. Since the accuracy of the etching process is limited, if the distance between the connecting bar and the connecting portion is too small, a part of the connecting portion will also melt, and it may be difficult to make the connecting portion into a desired size.

One aspect of the embodiment is made in view of the above, and an object of the present invention is to provide a lead frame capable of accurately forming a connecting portion that connects tip ends of leads to electrically connect them. And

A lead frame according to an aspect of the embodiment includes a plurality of unit lead frames and a connecting bar. The unit lead frame has a die pad, a plurality of leads, and a connecting portion that connects the tip portions of the adjacent leads, and is arranged in a matrix. The connecting bar connects the unit lead frames. Further, the connecting bar includes a lead support bar that supports a base end portion of the lead. The lead support bar has a region facing the connecting portion, which is cut away in a direction away from the connecting portion.

According to one aspect of the embodiment, it is possible to provide a lead frame capable of accurately forming the connecting portion that connects the tip portions of the leads to each other to electrically connect the lead portions.

FIG. 1 is a schematic diagram and an enlarged plan view of a lead frame according to an embodiment. FIG. 2 is an enlarged plan view of the lead frame according to the first modification of the embodiment. FIG. 3 is an enlarged plan view of a lead frame according to Modification 2 of the embodiment. FIG. 4 is an enlarged plan view of a lead frame according to Modification 3 of the embodiment. FIG. 5 is a cross-sectional view taken along the line AA shown in FIG. 4 according to the second region and its modification. FIG. 6 is an enlarged plan view of a lead frame according to Modification 4 of the embodiment. FIG. 7 is an enlarged plan view of a lead frame according to Modification 5 of the embodiment. FIG. 8 is an enlarged plan view of a lead frame according to Modification 6 of the embodiment. FIG. 9 is an enlarged plan view of a lead frame according to Modification 7 of the embodiment. FIG. 10 is an enlarged plan view of a lead frame according to Modification 8 of the embodiment.

An embodiment of a lead frame disclosed in the present application will be described below with reference to the accompanying drawings. The present invention is not limited to the embodiments described below.

First, the outline of the lead frame according to the embodiment will be described with reference to FIG. A lead frame 1 shown in FIG. 1 is a MAP type lead frame used for manufacturing a SON (Small Outline Non-leaded package) type semiconductor device.

Although the embodiment shows a lead frame used for manufacturing a SON type semiconductor device, it is applicable to a lead frame used for manufacturing another type of semiconductor device, for example, a QFN (Quad Flat Non-leaded package) type semiconductor device. You may

The lead frame 1 has a rectangular frame body 16 in a plan view, and a plurality of unit lead frames 10 are arranged in a matrix in the frame body 16. Around the unit lead frame 10, a plurality of connecting bars 15 whose both ends are supported by a frame body 16 are arranged in a grid pattern.

The unit lead frame 10 has a die pad 11, a plurality of leads 12, a connecting portion 13, and a support bar 14. Further, the plurality of connecting bars 15 have lead support bars 15a that support the base end portions 12b of the plurality of leads 12. The plurality of lead support bars 15a are arranged in the lateral direction of the lead frame 1, but may be arranged in the longitudinal direction of the lead frame 1.

The die pad 11 is formed in a rectangular shape in a plan view, and is provided in the central portion of the unit lead frame 10. A semiconductor chip (not shown) can be mounted on the front surface side of the die pad 11.

The plurality of leads 12 are arranged side by side between the die pad 11 and the lead support bar 15a, and the respective tip portions 12a extend from the lead support bar 15a toward the die pad 11. The lead 12 functions as an external terminal of the semiconductor device by being electrically connected to the electrode of the semiconductor chip arranged on the die pad 11 with a bonding wire or the like.

The connecting portion 13 connects the tip portions 12a of the adjacent leads 12 to electrically connect the adjacent leads 12 to each other. Like the lead 12, the connecting portion 13 can be used as a region electrically connected to an electrode of a semiconductor chip arranged on the die pad 11 by a bonding wire or the like.

If the distance between the connecting portion 13 and the lead supporting bar 15a is too narrow, a part of the connecting portion 13 will also melt due to the precision of the etching process and the like, and it will be difficult to make the connecting portion 13 a desired size. There is a fear.

Therefore, in the lead support bar 15a of the lead frame 1 according to the embodiment, the first region 15c facing the connecting portion 13 is cut away in a direction away from the connecting portion 13. In other words, in the lead support bar 15a, the first region 15c facing the connecting portion 13 is recessed in a direction away from the connecting portion 13. In other words, in the lead support bar 15a, the first region 15c facing the connecting portion 13 has a non-forming portion on at least a part of the connecting portion 13 side.

As a result, the distance between the connecting portion 13 and the lead support bar 15a can be set to a distance that does not cause a problem in the accuracy of etching processing. Can be well formed. Therefore, unbonding of the bonding wire to the connecting portion 13 can be suppressed.

Here, the distance between the connecting portion 13 and the lead supporting bar 15a cut away from the connecting portion 13 is preferably 90% or more of the thickness of the thickest portion of the lead frame 1, for example. .. Accordingly, it is possible to prevent a part of the connecting portion 13 from being melted (so-called over-etching) during the etching process, and to secure a bonding wire bonding region in the connecting portion 13. The "spacing" described here is the distance between the end surface of the connecting portion 13 on the lead supporting bar 15a side and the end surface of the lead supporting bar 15a on the connecting portion 13 side.

In the lead frame 1 shown in FIG. 1, the connecting portion 13 is formed by extending substantially parallel to the lead supporting bar 15a, and the leads facing the connecting portion 13 are arranged so that the distance from the connecting portion 13 is substantially constant. Although a part of the first region 15c of the support bar 15a is cut out, the present invention is not limited to this example.

For example, a wedge shape in which the central portion of the first region 15c in the extending direction of the lead support bar 15a (hereinafter referred to as the central portion of the first region 15c) is cut away from the connecting portion 13 from other portions, It may have an arc shape or the like.

Further, the first region 15c may be cut out so that at least a part thereof divides the lead support bar 15a. For example, in the lead frame 1A shown in FIG. 2, both ends of the first region 15c are partially cut away in a direction away from the connecting portion 13, and a region corresponding to the center of the first region 15c is lead-supported. An example is shown in which the bar 15a is entirely cut out so as to be divided.

Accordingly, the connecting portion 13 can be brought close to the lead supporting bar 15a at least in the central portion of the first region 15c. Therefore, the width of the connecting portion 13 can be increased accordingly. For example, the width of a part of the connecting portion 13 can be increased by forming the central portion of the connecting portion 13 in a convex shape.

Further, like the lead frame 1B shown in FIG. 3, the entire first region 15c may be cut out so as to divide the lead support bar 15a. Thereby, the connecting portion 13 can be brought closer to the lead supporting bar 15a side in the entire first region 15c. Therefore, the width of the connecting portion 13 can be increased as a whole.

Further, since the distance between the connecting portion 13 and the lead supporting bar 15a can be reduced to the utmost limit, the size of the die pad 11 can be increased accordingly.

Even if the lead support bar 15a is divided, since all the leads 12 are supported via the connecting portions 13, the leads 12 do not fall off the lead frames 1A and 1B.

Here, returning to the description of FIG. 1, the configuration of the lead frame 1 will be described in more detail. In the following, first, the etching process of the lead frame 1 will be described, and then the configuration of the lead support bar 15a will be further described.

The lead frame 1 according to the embodiment is formed by etching a metal plate made of copper, copper alloy, iron-nickel alloy, or the like. The etching process includes, for example, a full etching process in which both sides are etched to form an opening, and a half etching process in which the back side is etched to reduce the thickness.

Hereinafter, the part that has been subjected to the half-etching process is referred to as the "half-etched part", and the part that has not been subjected to the etching process and has the same thickness as the metal plate before the etching process is the "full metal part". I call it. In the enlarged plan view of the specification of the present application, the “half-etched portion” of the “full metal portion” and the “half-etched portion” is hatched for easy understanding.

As shown in FIG. 1, the connecting bar 15 including the lead supporting bar 15a is composed of a half-etched portion. The lead 12 has a half-etched portion at the peripheral edge of the tip portion 12a, and a full-metal portion other than that. The connecting portions 13 are all composed of half-etched portions.

Therefore, the connecting portion 13 and the lead supporting bar 15 a facing the connecting portion 13 are connected by the full metal portion provided on the lead 12. Therefore, the connecting portion 13 and the lead supporting bar 15a are firmly connected to each other, and the connecting portion 13 can improve the strength of the lead supporting bar 15a which is reduced by notching the first region 15c. Thereby, the deformation of the lead frame 1 in the lateral direction can be suppressed.

When the lead support bar 15a shown in FIGS. 2 and 3 is cut out so as to divide the first region 15c, the width of the connecting portion 13 is equal to or larger than the width of the lead support bar 15a. By increasing the width, the strength of the lead support bar 15a can be improved.

Further, although the lead support bars 15a are arranged in the lateral direction of the lead frame 1, the lead support bars 15a are arranged in the longitudinal direction of the lead frame 1 and the die pad support for supporting the die pad 11 via the support bars 14 is provided. The bars 15b may be arranged in the lateral direction.

As described above, by arranging the die pad support bars 15b not cut out in any of the regions in the short-side direction, the strength in the short-side direction of the lead frame 1 can be improved more than the strength in the long-side direction.

Regarding the reduction in strength in the longitudinal direction of the lead frame 1 due to the arrangement of the lead support bars 15a with the first regions 15c cut out, for example, by supporting both ends in the lateral direction of the lead frame 1. It is possible to suppress deformation (for example, bending) in the longitudinal direction during the transportation of the lead frame 1.

Further, in the embodiment, since the lead frame 1 used for manufacturing the SON type semiconductor device is shown, the lead support bars 15a are arranged only in the lateral direction (or the longitudinal direction) of the lead frame 1. ..

However, in the case of a lead frame used for manufacturing a QFN type semiconductor device, for example, the lead support bars 15a are arranged in both the longitudinal direction and the lateral direction of the lead frame.

Subsequently, various means for improving the strength of the lead support bar 15a itself are shown in FIGS. As such a means, for example, at least a part of the lead support bar 15a may be formed of a full metal part. In the lead frame 1C shown in FIG. 4, a region of the lead support bar 15a that faces the die pad 11 and a second region 15d that does not face the connecting portion 13 is formed of a full metal portion.

As a result, the strength of the entire lead support bar 15a can be improved by using the full metal portion having higher strength than the half-etched portion. Therefore, the deformation of the lead frame 1C in the lateral direction can be suppressed.

Further, with reference to FIG. 5, the second region 15d formed of a full metal part and its modification will be described. Note that in FIGS. 5B and 5C, a portion corresponding to the contour of the cross section shown in FIG. 5A is indicated by a broken line for easy understanding.

As shown in FIG. 5A, the second region 15d has a rectangular shape in cross section, and is composed of a full metal portion. With this structure, the lead frame 1C (see FIG. 4) is formed from a metal plate having a predetermined plate thickness, and when the width W1 is set to a predetermined value, the cross-sectional area of the second region 15d can be maximized. it can. Therefore, the strength of the second region 15d can be maximized.

On the other hand, the configuration of the second region 15d is not limited to the configuration shown in FIG. For example, as shown in FIG. 5B, the half-etched etching portion 17a may be formed on the back surface side of the side portion. Further, as shown in FIG. 5C, it is also possible to form an etching portion 17b that is etched so that the side surface has a shape that widens toward the top.

The etching portions 17a and 17b can be formed in the same etching process as the half etching portion provided on the lead 12, the connecting portion 13, and the like.

Here, in each of the modified examples, the cross section has an inverted trapezoidal shape, and the central portion is composed of a full metal portion. Therefore, the strength of the second region 15d can be secured by the full metal portion.

Further, in each of the modified examples, the side portions are etched, so that in the manufacturing process of the semiconductor device, the cross-sectional area of the metal portion cut off at the time of dicing performed along the connecting bar 15 after collective resin sealing is performed. small. Therefore, it is possible to suppress the abrasion of the rotary blade during dicing.

That is, in any of the modified examples, the strength of the second region 15d and the long life of the rotary blade can both be achieved.

As a next strength improving means for the lead supporting bar 15a, in the lead frame 1D shown in FIG. 6, the first region 15c of the lead supporting bar 15a is composed of a full metal part.

This makes it possible to directly improve the strength of the first region 15c, which is cut out and whose strength is somewhat reduced, by using the full metal portion, so that the deformation of the lead frame 1D in the lateral direction is effectively performed. Can be suppressed.

As a next means, in the lead frame 1E shown in FIG. 7, the side of the first region 15c opposite to the side of the connection portion 13 that is cut out protrudes away from the connection portion 13. That is, when compared with the lead frame 1 shown in FIG. 1, the width of the lead support bar 15a in the first region 15c is wider.

As a result, the strength of the first region 15c, which is somewhat lowered, can be directly improved, so that the deformation of the lead frame 1E in the lateral direction can be effectively suppressed.

When the width of the lead supporting bar 15a in the first region 15c is widened as described above, the first region 15c is arranged so as not to protrude from the dicing line DL, which is a portion cut off during the above dicing. Good. This makes it possible to suppress the occurrence of burrs on the cut surface during dicing due to the protruding portion.

The width of the lead support bar 15a in the first region 15c of the lead frame 1E may be narrower than the second region 15d, may be the same width, or may be wider. The width of the lead support bar 15a in the first region 15c may be a width that does not protrude from the dicing line DL.

As a next means, in the lead frame 1F shown in FIG. 8, when the entire first area 15c is cut out so as to divide the lead support bar 15a, the lead adjacent to the cut-out first area 15c is formed. The support bar 15a is composed of a full metal part. In other words, the portion of the lead support bar 15a that supports the base end portion 12b of the lead 12 connected to the connecting portion 13 is formed of a full metal portion.

This makes it possible to directly improve the strength of the portion of the lead support bar 15a, which is adjacent to the first region 15c, which is wholly cut out, so that the strength is somewhat reduced by using the full metal portion. Therefore, the deformation of the lead frame 1F in the lateral direction can be suppressed.

Next, a further modified example of the embodiment will be described with reference to FIGS. 9 and 10. In the lead frame 1G shown in FIG. 9, the first region 15c is also cut out in a direction approaching the connecting portion 13 on the side opposite to the notched connecting portion 13 side. That is, when compared with the lead frame 1 shown in FIG. 1, the width of the lead support bar 15a in the first region 15c is narrow.

As a result, the cross-sectional area of the metal portion of the first region 15c can be reduced, so that wear of the rotary cutting tool during dicing can be suppressed. Therefore, the life of the rotary blade can be extended.

In the lead frame 1H shown in FIG. 10, the connecting portions 13 are respectively connected from the leading end 12a of one lead 12 to the leading ends 12a of the leads 12 adjacent to both sides of the lead 12. That is, the tip portions 12 a of the three leads 12 arranged side by side are integrally connected by the two connecting portions 13.

As a result, a large number of bonding wires can be connected to the tip portion 12a of the lead 12 having a large area and the connecting portion 13 that are integrally connected.

Although FIG. 10 shows an example in which three leads 12 are integrally connected, the number of leads 12 that can be integrally connected is not limited to three. For example, in the lead frame 1H, four or more leads 12 may be integrally connected.

Finally, features of the embodiment other than the above will be described. In the lead frame 1 and the like, the width of the lead support bar 15a in the first region 15c is smaller than the width of the lead support bar 15a in the second region 15d. As a result, the entire lead support bar 15a can be held within the range of a predetermined region extending along the extending direction.

This can prevent the lead support bar 15a from protruding from the dicing line DL (see FIG. 7) when dicing along the extending direction of the connecting bar 15. Therefore, the protruding portion can suppress the occurrence of burrs on the cut surface during dicing.

Further, in the lead frame 1 and the like, the connecting portion 13 is formed of a half-etched portion, and a predetermined space is provided between the connecting portion 13 and the lead support bar 15a. Here, the sealing resin flows into the back side of the etched connecting portion 13 from such a space during the collective resin sealing in the manufacturing process of the semiconductor device, so that the connecting portion 13 is exposed from the sealing resin of the semiconductor device. Can be completely sealed without.

Here, if the connecting portion 13 is exposed from the sealing resin, moisture or the like enters the inside of the semiconductor device from the interface between the exposed portion and the sealing resin, which adversely affects the reliability of the semiconductor device. May give. However, with the above-described configuration, it is possible to prevent moisture and the like from entering the inside of the semiconductor device, so that a highly reliable semiconductor device can be realized.

Further, in the lead frame 1 and the like, the leads 12 adjacent to each other are electrically connected to each other using the connecting portion 13. That is, since it is not necessary to use a bonding wire to electrically connect the leads 12 adjacent to each other, a region for joining the bonding wire to the leads 12 is also unnecessary.

As a result, in the lead 12, it is possible to secure a sufficient bonding wire bonding region for connecting the electrode of the semiconductor chip. Therefore, it is possible to suppress unbonding of the bonding wire that connects the lead 12 and the semiconductor chip.

Further, in the lead frame 1 and the like, adjacent leads 12 are connected to each other using a connecting portion 13 having a larger cross-sectional area than the bonding wire. Therefore, it is possible to electrically connect the adjacent leads 12 with high conductivity as compared with the case of using the bonding wire.

Further, in the lead frame 1 and the like, a connecting portion 13 is provided on each of the leads 12 arranged on both sides of one lead supporting bar 15a. Further, the pair of connecting portions 13 are arranged so as to be displaced in the extending direction by the distance between the adjacent leads 12.

Although the respective embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit thereof.

As described above, the lead frame 1 (1A to 1H) according to the embodiment includes the plurality of unit lead frames 10 and the connecting bar 15. The unit lead frame 10 has a die pad 11, a plurality of leads 12, and a connecting portion 13 that connects the tip portions 12 a of the adjacent leads 12 and is arranged in a matrix. The connecting bar 15 connects the unit lead frames 10 to each other. Further, the connecting bar 15 includes a lead support bar 15a that supports the base end portion 12b of the lead 12. The lead support bar 15a has a region (first region 15c) facing the connecting portion 13 cut away in a direction away from the connecting portion 13. This makes it possible to accurately form the connecting portion 13 that connects the tip portions 12a of the leads 12 to each other and electrically connects them.

In the lead frame 1C (1D) according to the embodiment, at least a part of the lead support bar 15a has the same thickness as the thickest part (full metal part) of the lead frame 1C (1D). Thereby, the deformation of the lead frame 1C (1D) can be suppressed.

Further, in the lead frame 1D according to the embodiment, the region (first region 15c) facing the connecting portion 13 has the same thickness as the thickest portion (full metal portion) of the lead frame 1D. Thereby, the deformation of the lead frame 1D can be effectively suppressed.

Further, in the lead frame 1 (1C, 1D, 1G, 1H) according to the embodiment, a region (first region 15c) facing the connecting portion 13 faces the die pad 11 in the lead supporting bar 15a, and the connecting portion is formed. The width is narrower than the area (second area 15d) that does not face 13. Thereby, when dicing along the extending direction of the connecting bar 15, it is possible to suppress the occurrence of burrs on the cut surface due to the lead supporting bar 15a.

Further, in the lead frame 1A (1B) according to the embodiment, at least a part of the region (first region 15c) facing the connecting portion 13 is cut out so as to divide the lead support bar 15a. Thereby, the width of the connecting portion 13 can be increased.

Further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspects of the present invention are not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

1, 1A to 1H Lead frame 10 Unit lead frame 11 Die pad 12 Lead 12a Tip part 12b Base end part 13 Connection part 14 Support bar 15 Connecting bar 15a Lead support bar 15b Die pad support bar 15c First area 15d Second area 16 Frame body

Claims (5)

A die pad, a plurality of leads, and a plurality of unit lead frames arranged in a matrix, having a connecting portion that connects the tip portions of the adjacent leads to each other;
A connecting bar connecting the unit lead frames to each other,
The connecting bar is
A lead support bar supporting the proximal end of the lead,
The lead support bar is
A lead frame, wherein a region facing the connecting portion is cut away in a direction away from the connecting portion. The lead support bar is
The lead frame according to claim 1, wherein at least a part of the lead frame has the same thickness as the thickest part of the lead frame. The region facing the connecting portion,
The lead frame according to claim 2, wherein the lead frame has the same thickness as the thickest part of the lead frame. The region facing the connecting portion,
The lead frame according to claim 1, wherein a width of the lead support bar is narrower than a portion of the lead support bar that faces the die pad and does not face the connecting portion. The region facing the connecting portion,
At least one part is notched so that the said lead support bar may be divided, The lead frame as described in any one of Claims 1-4 characterized by the above-mentioned.

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