JPH0766355A - Semiconductor device - Google Patents

Abstract

PURPOSE:To provide a semiconductor device wherein the dimensioned accuracy of depression processing of a die pad is stabilized and any stay shift is scarcely generated at the time of molding. CONSTITUTION:A semiconductor device 10 has a die pad 12 which is fixed to a lead frame by suspension parts 18, 20 stretching from a peripheral part. Slits 14 arranged in the length direction and slits 16 arranged in the width direction are formed in the die pad. The suspension parts 18, 20 stretch outward from the peripheral part isolated from die pad regions 15, 22 in the length direction virtual extension parts of the respective slits 14, 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly, to a die pad which maintains a necessary precision of a deep press even in a large semiconductor device and is less likely to cause a stay shift during resin sealing. The present invention relates to a semiconductor device having a structure.

[0002]

2. Description of the Related Art In a resin-sealed thin package (TSOP TQFP) whose production has been increasing in recent years, in order to improve the processing accuracy and quality of the package structure, the processing accuracy of the lead frame is set within an allowable value. It is important to keep the processing accuracy in the resin encapsulation process after the packaging. Therefore, control of the processing accuracy of the lead frame has become a very important weight in quality control of semiconductor devices. By the way, in order to improve the processing accuracy of the lead frame, it is important to study the die pad structure that constitutes the main part of the lead frame.

FIG. 6A is a plan view showing a conventional die pad structure of a semiconductor device, and FIG. 6B is a perspective view thereof. In the conventional die pad structure 60, as shown in FIG.
As shown in (a) and (b), slits 64 (in this case, two slits) are arranged in the die pad 62 in the longitudinal direction, and slits 66 (in this case, two slits) are arranged in the width direction. ing. The hanging portions extend from the four sides of the die pad 62 so as to face each other.
Are supported by a pair of hanging portions 68 in the longitudinal direction and a pair of hanging portions 70 in the width direction. Further, as shown in FIG. 6B, a large number of inner leads 72 extend outward around the die pad 62, and the semiconductor chip (not shown) die-bonded to the die pad 62 is a gold wire ( These are connected to the inner leads 72 by (not shown).

7 (a), 7 (b), 7 (c) and 7 (d) respectively show a die pad structure or a large die pad slit and suspension which are different from the suspension portion and slit arrangement shown in FIG. The arrangement of parts is shown.

Slits 64, 6 provided in the die pad 62
6 is to disperse the thermal stress due to reflow at the time of board mounting,
This suppresses the occurrence of cracks in the sealing resin. Therefore, the slit is indispensable for preventing the occurrence of cracks in the thin resin-sealed package and improving the product yield. Also, due to the recent increase in the size of semiconductor chips, the pair of hanging portions 68 in the longitudinal direction of the die pad cannot support the large die pad structure, and a wire bonding step for connecting a gold wire, which is a later step,
Or because it became difficult to guarantee accuracy in the resin encapsulation process,
Providing a pair of hanging portions 70 also on the widthwise edge of the die pad,
The suspension strength of the die pad structure is reinforced.

[0006]

However, as the size of the semiconductor device increases, the size of the die pad itself becomes larger and larger, and it is difficult to maintain the required die pad strength and the precision of the depth pressing with the above-mentioned conventional die pad structure. Therefore, there has been a problem that a stay shift occurs during molding.

The term "depressing" means that the hanging portion of the lead frame is stamped by a press, and the processing position of the depressing is determined according to the hanging position of hanging the die pad. The accuracy of deep pressing means the dimensional accuracy of deep pressing. The stay shift refers to a phenomenon in which, when a molding resin is injected into a molding die and molding is performed, the lead frame moves vertically from an initial setting position of the molding die due to the injection pressure of the molding resin.

In view of the above problems, it is an object of the present invention to provide a semiconductor device having an improved die pad structure which maintains the required precision of the depression process and is less likely to cause a stay shift during molding. Is.

[0009]

Means for Solving the Problems The inventors of the present invention have studied the precision of a large semiconductor device, that is, the precision of a large die pad structure, and obtained the following findings. Firstly, the stress generated during the deep pressing is mainly a tensile stress generated in the hanging portion 70, and will be described with reference to FIG. 4A. The die pad at the base end of the hanging portion via the hanging portion 70 will be described. It concentrates on a part (A area shown in FIG. 4A). In the conventional semiconductor device, since the hanging portion 70 extends from the die pad region B (the virtual extension of the slit 66 in the longitudinal direction),
Stress due to the deep pressing is concentrated on that portion, and since the strength of the portion is reduced due to the opening of the slit, deformation is likely to occur, and thus the precision of the deep pressing is reduced. It was also found that the stress concentration state on the die pad side, and hence the degree of deformation, differ depending on the positional relationship between the slit of the die pad and the hanging portion.

Second, the phenomenon of stay shift was studied. The phenomenon of stay shift will be described below with reference to the accompanying drawings. FIG. 5A is a perspective view of the semiconductor device, and FIG.
5A is a cross-sectional view of the semiconductor device of FIG. 5A taken along the line YY ′, and FIG. 5C is a cross-sectional view of the semiconductor device of FIG. 5A taken along the line XX ′. As shown in FIGS. 5B and 5C, in the semiconductor device, the semiconductor element 72 is fixed on the die pad 70, the semiconductor chip 72 is connected to the inner lead 76 by the gold wire 74, and the periphery thereof is the outer lead. 7
8 is exposed and is covered with a sealing resin 80. In addition, 82 shows a hanging part. In order to suppress the occurrence of stay shift when generating such a package structure, it is necessary that the a dimension and the b dimension shown in FIG. 5C be a≈b, and the stay shift is on the b side. The die pad 70 moves to a> b, or the die pad 7 is moved to the a side.
It occurs when 0 moves and becomes a <b, and the dimensions of a and b are different.

In FIG. 5 described above, if the c dimension of the die pad 70 of the lead frame, that is, the dimension of the deep pressing is within the allowable working accuracy, a≈b, and the stay shift hardly occurs. However, when the precision of the depth processing is varied and the error in the c dimension of the die pad 70 of the lead frame exceeds the specified tolerance, a and b are different and the vertical balance is lost in the molding die. Thereby,
When the molding resin is injected, the injection pressure acts strongly on the side with a large gap and presses the lead frame against the side with a small gap, causing a stay shift.

In order to achieve the object based on the above findings, the semiconductor device according to the present invention has a die pad fixed to a lead frame by a hanging portion extending from a side peripheral portion, and a slit is formed in the die pad. In the semiconductor devices arranged in the horizontal direction and the width direction, the hanging portion extends outward from a die pad side peripheral portion that is separated from a region of a virtual extension portion in the longitudinal direction of the slit.

According to a modified example of the present invention, in the above-mentioned semiconductor device, the slits are arranged in parallel in a plurality of rows, and the hanging portion is outward from the die pad side peripheral portion separated from the region of the virtual extension portion in the longitudinal direction of the slit. It is characterized by extending to.

[0014]

In the inventions of claims 1 and 2, unlike the conventional die pad structure, as shown in FIG. 4 (b), since the suspending portion 70 does not exist in the region B of the virtual extension portion of the slit 66, the suspending portion 70 is suspended. The stress generated in the portion 70 is dispersed through its base end into a wide region (b in FIG. 4B is longer than a in FIG. 4A). Therefore, the degree of stress concentration due to the deep pressing is smaller than that of the conventional one, and therefore, the deformation is hardly generated in the region, and the working accuracy is significantly improved.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in more detail based on embodiments with reference to the accompanying drawings. FIG. 1A is a plan view of a die pad showing the arrangement of slits and suspension parts of an embodiment of a semiconductor device according to the present invention, and FIG. 1B is a perspective view of the main part of the semiconductor device shown in FIG. 1A. is there. Semiconductor device 1 of the present embodiment
As shown in FIG. 1A, the die pad 12 of 0 has a slit row 14 arranged along the longitudinal center line of the die pad 12, and two slit rows 1 arranged in parallel in the width direction.
6, two hanging portions 1 provided to face the end in the longitudinal direction
8 and two hanging portions 2 provided so as to face the widthwise end edges.
It has 0.

The slit array 14 in the longitudinal direction includes three slits 14A, 14B and 1 arranged in a line in the longitudinal direction.
The slit rows 16 in the width direction are made of 4C, and each two slit rows 16 are 2
16 slits 16A and 16B arranged in parallel with each other,
C and 16D, and each width direction slit row is arranged so as to be in the middle of the longitudinal direction slit 14.

The longitudinal suspension 18 extending outwardly from the longitudinal end of the die pad 12 is bifurcated at its proximal end 22 so that it extends from the die pad area 15 of the virtual extension of the longitudinal slit 14. It is formed to be separated. On the other hand, the width-direction suspending portion 20 extending outward from the width-direction side edge of the die pad 12 is located just in the middle of the width-direction slits 16 arranged in two rows. In other words, the slit 14 extends outward from the edge of the slit 14 that is virtually extended in the longitudinal direction and is separated from the die pad region 22. Reference numeral 72 is an inner lead.

With the above configuration, the base end of the hanging portion 20 in the width direction has the slit 1 in the width direction as compared with the conventional semiconductor device.
6, and the base end of the suspending portion 18 in the longitudinal direction is also separated from the slit 14 in the longitudinal direction. As a result, as explained below,
The required precision of the lead frame deep pressing is maintained, and the stay shift during molding is suppressed. That is, referring to FIG. 4B, the description will be made in comparison with the conventional die pad structure shown in FIG. 4A.
As shown in (b), since the suspending portion 70 does not exist in the region B of the virtual extension portion of the slit 66, the stress generated in the suspending portion 70 has a wide region via its base end (FIG. 4 (b)). 4b is longer than a in FIG. 4A). Therefore,
The degree of stress concentration due to the deep-press processing is smaller than that of the conventional one, so that there is almost no deformation and the processing accuracy is greatly improved.

2 (a), 2 (b) and 2 (c) and FIG.
(D), (e) and (f) are modified examples of FIG.
The arrangement of various slits and suspension portions different from the conventional positional relationship between slits and suspension portions shown in FIG. 7 is shown. In either arrangement, the hanging portion extends from the side edge of the die pad that is separated from the die pad region of the virtual extension in the longitudinal direction of the slit row.

[0020]

According to the first and second aspects of the present invention, the hanging portion extends outward from the die pad side peripheral portion which is separated from the region of the virtual extension portion in the longitudinal direction of the slit.
The stress generated during the deep pressing is not dispersed and concentrated in a wide area, and the die pad area near the base end of the hanging portion is not deformed. Therefore, even for large semiconductor devices,
It is possible to maintain the required precision of the depth processing, and the stay shift does not occur even during resin sealing. By manufacturing the semiconductor device according to the present invention, the yield of large semiconductor packages is improved.

[Brief description of drawings]

FIG. 1A is a plan view of a die pad showing an arrangement of slits and suspensions of an embodiment of a semiconductor device according to the present invention;
FIG. 1B is a perspective view of the main part of the semiconductor device shown in FIG.

2 (a), (b) and (c) show arrangements of slits and suspensions in a modified example of the semiconductor device of FIG. 1, respectively.

3 (d), (e) and (f) show the arrangement of slits and suspensions in a modification of the semiconductor device of FIG. 1, respectively.

FIG. 4A, FIG. 4B and FIG. 4C are a perspective view and a sectional view of a resin-sealed semiconductor device, respectively.

5 (a) and 5 (b) are diagrams for explaining stress concentration due to deep pressing.

6A is a plan view of a die pad showing the arrangement of a slit and a hanging portion of a conventional semiconductor device, and FIG. 6B is a perspective view of a main part of the semiconductor device shown in FIG. 6A. is there.

7 (a), (b) and (c) show another arrangement of slits and suspensions of a conventional semiconductor device, respectively.

[Explanation of symbols]

10 Semiconductor device according to the present invention 12 Die pad 14 Slit row arranged along the longitudinal centerline of the die pad 16 Slit row arranged in two rows in parallel in the width direction of the die pad 18 Opposed to the longitudinal end of the die pad Suspended part provided 20 Suspended part provided so as to face the widthwise end edge of the die pad

Claims (2)

[Claims] 1. A semiconductor device having a die pad fixed to a lead frame by a suspending portion extending from a side peripheral portion, wherein slits are arranged in a longitudinal direction and a width direction on the die pad, wherein the suspending portion is the slit. A semiconductor device, which extends outward from a die pad side peripheral portion separated from a region of a virtual extension portion in the longitudinal direction. 2. The slits are arranged in parallel in a plurality of rows, and the suspending portion extends outward from a die pad side peripheral portion which is separated from a region of a virtual extension portion in the longitudinal direction of the slit. The semiconductor device according to claim 1.