JP3058755B2 - Lead frame and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an leadframe and its production how relates further lead frame and a manufacturing how the stage for mounting the semiconductor chip is supported by the support bars in detail.

[0002]

2. Description of the Related Art As a lead frame, as shown in FIG. 4, a lead frame 10 in which a stage 12 for mounting a semiconductor chip is supported by a plurality of support bars 14 extending from a frame 15 is used. ing. In the lead frame 10 shown in FIG. 4, a plurality of dimples 16 are provided on the stage 12 in order to improve the bonding between the mounted semiconductor chip and the stage 12.
May be provided. Further, after being sealed with a resin or the like, the support bars 14 and 14 are provided with concave grooves or V-shaped grooves in order to prevent moisture from entering the sealing resin along the support bars 14 and 14.
A groove may be formed. Such a plurality of dimples 16 are provided on the stage 12 by dimple processing or press processing for forming concave grooves or V-grooves on the support bars 14, 14.
Of the stage 12 may be tilted or warped. For this reason, in a lead frame which needs to be subjected to press working for providing such a plurality of dimples 16, the bent portions 108 and the cranks shown in FIGS. The strain absorbing portion 100 including the portion 110 and the like is formed.

[0003]

SUMMARY OF THE INVENTION Such a strain absorbing section 10 is described.
By forming 0 in the middle of the support bars 14, 14, even if the stage 12 and the support bars 14, 14 are distorted, the bent portion 108 and the crank portion 110 of the strain absorbing portion 100 can be elastically deformed and absorbed. . However, in order to provide the strain absorbing portion 100 shown in FIG. 5 in the middle of the support bar 14, a gap in which the bent portion 108 and the crank portion 110 can be formed is required. Moreover, in order to sufficiently absorb the distortion generated in the stage 12 and the like, the shape of the bent portion 108 and the crank portion 110 must be large, and at present, there is a demand for a multi-pin lead frame. It is difficult to increase the size of the strain absorbing section 100. Further, if the strain absorbing portion 100 is formed in the middle of the support bar 104, the strength of the support bar 14 is also reduced.
When an external force, in particular, an external force in the vertical direction or the horizontal direction is applied to the support bar 14, there is also a problem that the support bar 14 is easily deformed. An object of the present invention, even when miniaturized strain absorbing portion to hold the strength of the support bars, the lead frame and the manufacturing how can be sufficiently absorb the distortion such as warpage occurring on the stage or the like Is to provide.

[0004]

SUMMARY OF THE INVENTION The present inventor has extensive investigations to achieve the above object, the shape in the middle of the support bar
In the space of the formed annular part, connect the support bar and the annular part.
Forming a straight intersection that extends in a direction perpendicular to the virtual straight line
And the distortion which connects both ends of this straight intersection to the annular part
After forming the absorbing portion, by coining the straight crossing portion, it was found that even if the strain absorbing portion was downsized, the strain accumulated on the stage or the like could be sufficiently absorbed, and the present invention was reached.

That is, according to the present invention, in a lead frame in which a support bar for supporting a stage on which a semiconductor chip is mounted is formed, the annular portion and the support are provided in the space of the annular portion formed in the middle of the support bar. extend in a direction intersecting the virtual straight line connecting the two joining portions of the bar, both ends
Has a straight crossing portion connected to the annular portion.
Is formed, and at least the straight intersection is formed.
The lead frame is partially deformed and stretched .

Further, the present invention provides a method for manufacturing a lead frame in which a stage on which a semiconductor chip is mounted is supported by a support bar by press working, in a space of an annular portion formed in the middle of the support bar. straight intersecting portion extending in a direction intersecting the virtual straight line connecting the two joining portions between the annular portions and the support bar is formed and distortions at both ends, which are connected to the front Symbol annular portion of the straight intersection after forming the absorber is also a manufacturing how the lead frame, characterized by coining at least a portion of the straight intersection.

[0007] In the present invention comprising such a construction, the straight intersection, connecting both connection portions between the ring-shaped portion and the support bar
By extending in a direction substantially orthogonal to the virtual straight line, the amount of strain absorption of the strain absorbing portion can be maximized. In addition, each of the multiple support bars that support the stage
The formed annular section, to form a straight cross-section
Ri, can be absorbed as much as possible the distortion of such processing distortion,
Stage warpage and the like can be eliminated.

[0008]

According to the present invention, since the straight intersection is plastically deformed and elongated in the longitudinal direction by coining the straight intersection, the straight intersection is connected to both ends of the straight intersection. The annular portion extends in the longitudinal direction of the straight intersection. For this reason, the interval between the annular portions in the direction perpendicular to the straight intersection portion is reduced, and a tensile force acts on the support bar connected to the annular portion, so that the strain accumulated on the stage or the like can be absorbed. . Thus, in the present invention, plastic deformation is caused at the straight intersection by coining to absorb the strain accumulated on the stage or the like, so that the strain absorbing portion can be downsized and the strength of the support bar can be maintained. Further, since the distortion accumulated in the stage or the like is absorbed by coining of the straight intersection, it can be easily adjusted according to the degree of distortion accumulated in the stage so that the stage can be kept horizontal.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
FIG. 1 is a plan view of a strain absorbing portion 20a connected in the middle of each support bar 14 of the lead frame 10 shown in FIG. The distortion absorbing portion 20a of FIG.
And both ends are connected to the annular portion 17a in the space of the annular portion 17a.
Are constituted by sintered been a straight cross-section 22. This strain absorbing portion 20a is formed by the annular portion 17a and the support bar 1
The virtual straight line 24 connecting the two connecting portions with the straight line 4 and the straight crossing portion 22 are arranged to be orthogonal to each other.

In the lead frame in which the strain absorbing portion 20a shown in FIG. 1 is formed on each support bar 14, the distortion generated in the stage 12 or the like is partially or entirely coined at the straight crossing portion 22 of the strain absorbing portion 20a. Can be absorbed. That is, as shown in FIG. 2, the straight crossing portion 22 is elongated by coining a part or the entire surface of the straight crossing portion 22, and the connecting portion of the annular portion 17 a connected to both ends of the straight crossing portion 22 is It is pressed in the direction of arrow B. For this reason, the interval w between the connecting portions between the annular portion 17a and both ends of the straight intersection portion 22 is the interval W before coining (FIG. 1).
It is expanded more than. On the other hand, the interval H (FIG. 1) between the annular portions 17 a in the direction orthogonal to the straight intersection portion 22 is reduced to the interval h (FIG. 2) as the interval L increases.
A force in the direction of arrow C, that is, a force in the direction of pulling the stage 12 and the frame 15 acts on the support bars 14, 14 connected to the annular portion 17a in a direction perpendicular to the direction. Therefore, the distortion accumulated in the stage 12 and the like is absorbed.

Here, the greater the degree of extension of the straight crossing portion 22, the greater the tensile tension of the stage 12 and the frame 15 so that the degree of coining depends on the degree of strain accumulated on the stage 12 and the like. To adjust. Such adjustment of the degree of coining can be easily performed by adjusting the coining area. In addition, in the case of the same coining area, as the width of the straight intersection portion 22 is wider, the expansion due to coining becomes larger, but the strain absorbing portion 20a becomes larger.
For this reason, the width of the straight intersection 22 is determined according to the degree of distortion accumulated on the stage 12 or the like (for example, the degree of processing performed on the stage 12). Furthermore, as the intersection angle θ (FIG. 1) of the narrow band forming the diamond-shaped annular portion 17a becomes larger near the connecting portion between the diamond-shaped annular portion 17a and the support bars 14 in this embodiment, The annular portion 17a can be easily deformed by coining of the straight intersection portion 22, and the stage 1
Distortions such as 2 can be easily absorbed. However, the larger the intersection angle θ becomes, the larger the strain absorbing portion 20a becomes. Therefore, the strain absorbing portion 20a is determined depending on the size of the lead frame to be formed, the density of the inner leads, and the like. In this embodiment, each of the support bars 14 is provided with a strain absorbing portion.
When the distortion accumulated in the second and the like is small, the distortion absorbing portion 20a may be provided only in one support bar.

In the embodiment shown in FIGS. 1 and 2 described above, the annular portion 17a of the strain absorbing portion 20a is formed in a rhombic shape, but as shown in FIG. May be the strain absorbing portion 20b composed of the annular portion 17b. Further, as shown in FIG. 3 (b), two straight intersecting portions 22c may be provided in the annular portion 17c. Furthermore,
In the present embodiment shown in FIGS.
Connects both connecting portions of the annular portion 17a and the support bar 14.
The strain absorbing portion 20 is disposed on the support bar 14 so as to be orthogonal to the virtual straight line 24, but the strain absorbing portion 20 a is disposed so that the virtual straight line 24 and the straight intersection portion 22 are oblique to each other. May be. However, in this case, FIGS.
The deformation ratio of the straight crossing portion 22 tends to be smaller even if the same area is coined, as compared with the strain absorbing portion 20a shown in FIG.

[0013]

According to the present invention, even if the distortion absorbing portion is miniaturized, the distortion accumulated in the stage or the like can be sufficiently absorbed. Can be kept horizontal. Further, the strength of the support bar can be maintained, and deformation of the support bar due to an external force acting on the support bar can be prevented. For this reason, the lead frame of the present invention enables the support bar to be made thinner, and can respond to a request for increasing the number of pins of the lead frame.

[Brief description of the drawings]

FIG. 1 is a front view of a strain absorbing portion provided in the middle of a support bar of a lead frame of the present invention.

FIG. 2 is an explanatory diagram for explaining an operation of a strain absorbing section shown in FIG.

FIG. 3 is a front view showing another example of the strain absorbing section.

FIG. 4 is a front view showing a lead frame on which a strain absorbing portion of the present embodiment is formed.

FIG. 5 is a front view showing a conventional strain absorbing section.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Lead frame 12 Stage 14 Support bar 17a, 17b, 17c Annular part 20a, 20b, 20c Strain absorption part 22, 22b, 22c Straight intersection part 24 Virtual straight line

──────────────────────────────────────────────────の Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 23/50

Claims (4)

(57) [Claims] 1. A lead frame in which a support bar for supporting a stage on which a semiconductor chip is mounted is formed in a space of an annular portion formed in the middle of the support bar.
Extend in a direction intersecting the virtual straight line connecting the two joining portions between the annular portions and the support bar, two ends are connected to the annular portion
A strain absorbing part with a straight intersection is formed
At least a part of the straight intersection portion is deformed and extended.
Lead frame, characterized by being. 2. When a lead frame on which a stage on which a semiconductor chip is mounted is supported by a support bar is manufactured by press working, a space of an annular portion formed in the middle of the support bar is provided.
A straight crossing portion extending in a direction intersecting a virtual straight line connecting both connecting portions of the annular portion and the support bar is formed, and both ends of the straight crossing portion are connected to the annular portion. Forming a portion, and coining at least a part of the straight crossing portion. 3. The method for manufacturing a lead frame according to claim 2 , wherein the straight crossing portion is formed to extend in a direction substantially orthogonal to a virtual straight line connecting both connecting portions of the annular portion and the support bar. Wherein in the annular portion formed in each of the plurality of support bars for supporting the stage, according to claim 2 or claim 3 method for fabricating a lead frame according to form a straight cross-section.