JPH05243464A - Lead frame and plastic molded type semiconductor device using the same - Google Patents

Abstract

PURPOSE:To decrease the height of a loop part of a wire, by displaying each tip part of the inner leads. CONSTITUTION:A die pad 12 is bent and displayed at the shaded parts of both suspensions. The tip part 13a of each inner lead 13 is bent and displayed at the shaded part 13b, and lowered as compared with the other part 13c of the inner lead 13. The depth of display of each tip part 13a of the inner leads 13 is set in the manner in which the upper surface of the tip part 13a die-bonds an IC chip 5 to the displayed die pad 12. Since the bonding surface of the tip part 13a of the inner lead 13 is made lower than the other part 13c by displaying, a wire 7 can be pulled downward at the time of wire bonding. Thereby the height of a loop part 7a of the wire 7 can be decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame for thinning a semiconductor device and a resin-sealed semiconductor device (hereinafter simply referred to as "IC") using the lead frame.

[0002]

2. Description of the Related Art A conventional IC will be described with reference to the drawings.
FIG. 7 shows a cross-sectional view of a prior art IC. This IC
1 is a lead frame having a depressed die pad 2 in the central portion and a plurality of inner leads 3 and outer leads 4 corresponding to these in the peripheral portion, and an IC chip 5 on the upper surface of the die pad. Is die-bonded, each electrode (not shown) of the IC chip 5 and the upper surface of the tip portion 6 of each inner lead 3 corresponding thereto are bonded with a wire 7, and resin-sealed with a molding resin M. The outer lead 4 is bent outside the resin M toward the die pad (the SOP type or QFP type semiconductor device in the illustrated embodiment).

[0003]

Such an IC1 is
At present, an attempt has been made to reduce the total thickness T to, for example, 1 mm or less. However, the thinner the thickness T is, the more restricted the height of the loop portion 7a of the wire 7 is. It will be difficult to realize. That is, when an IC 1 having a thickness T of 1 mm or less is manufactured using a conventional lead frame, there arises a problem that the loop portion 7a of the wire 7 is exposed as shown in FIG.

Therefore, in order to prevent the exposure of the loop portion 7a, the height position of the IC chip 5 may be lowered while keeping the height position of the surface of the inner lead 3 unchanged. Lowering the position of I
A large difference occurs in the thickness of the resin Ma on the upper surface of the C chip 5 and the resin Mb on the lower surface of the die pad 2, and the entire package warps due to the difference in the coefficient of thermal expansion between the internal materials. This may cause troubles or cause defective soldering when mounted on the board. Therefore, it is not preferable to lower the height position of the electrodes of the IC chip 5.

An object of the present invention is to solve the above problems and obtain an IC that can be made thin.

[0006]

Therefore, according to the present invention, a lead frame having at least a plurality of inner leads for leading out a plurality of electrodes of a semiconductor chip to the outside and outer leads corresponding to the inner leads is provided. Each tip of the inner lead was depressed. And
A semiconductor chip is arranged in the central portion of the tip portions of the plurality of inner leads, and a plurality of electrodes of the semiconductor chip and the tip portions of the inner leads are connected to connect the semiconductor chip and the inner lead portions. The resin is sealed so that the thickness of the resin existing above the semiconductor chip is equal to the thickness of the resin existing below the semiconductor chip, and the outer lead is centered in the thickness of the sealing resin. The above problems have been solved by deriving from the section.

[0007]

Therefore, the height of the loop portion of the wire connecting the plurality of electrodes of the semiconductor chip and the respective tip portions of the inner leads can be reduced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. 1 is a cross-sectional view of a resin-encapsulated semiconductor device that is an embodiment of the present invention, FIG. 2 is a plan view of a lead frame that is an embodiment of the present invention, and FIG. 3 is a lead shown in FIG. It is a partially expanded perspective view of the front-end | tip part of the inner lead which is a component of a frame.

First, the lead frame of the present invention will be described with reference to FIG. Although only one unit of the lead frame is shown in this figure, a plurality of such unit lead frames are actually formed on one metal plate. Reference numeral 10 indicates such a unit of lead frame as a whole.

Like the conventional lead frame, the lead frame 10 has a die pad 12 arranged at the center,
In this embodiment, a plurality of inner leads 13 are arranged around the periphery of the die pad 12 at equal intervals around the periphery of the die pad 12, and outer leads 14 are arranged corresponding to the inner leads 13.

The die pad 12 is supported by stays 16 at both ends by suspensions 16, and the inner leads 13 and the outer leads 14 are supported by the stays 15 by tie bars 17 and side rails 18. ing. These components can be formed by stamping a flat plate of 42 alloy or copper-based material having a uniform thickness, for example, about 0.1 mm.

In the present invention, the die pad 12
Is bent and depressed at the slanted portions 16a of both suspensions 16 described above. In addition, the tip end portion 13a of each inner lead 13 is replaced with the shaded portion 13
The inner lead 13 was bent and depressed at a position lower than the other portions 13c of the inner lead 13. Other components, that is, the other portion 13c of the inner lead 13, the outer lead 14, the stay 15, the tie bar 17, and the side rail 18 are in the same plane. Inner lead 1 in Figure 3
3 is a partially enlarged view of the vicinity of the tip portion 13a.

The depth of depressing of each tip portion 13a of the inner lead 13 is determined by die-bonding an IC chip (reference numeral 20 in FIG. 1) to the die pad 12 whose upper surface is depressed. It is desirable to fold it so that it is located near the central portion of the entire thickness of or less than or equal to the height.

A die padless lead frame has been devised as a means for reducing the thickness of an IC. In such a lead frame, the upper surface of the tip portion of the inner lead similar to that described above is The IC when an IC chip is mounted in the center of the inner leads
It is preferable to bend the chip so that it is located at the height of the center of the chip or less.

Next, an embodiment of the IC of the present invention constructed by using such a lead frame 10 will be described with reference to FIG. The lead frame 10 of FIG. 2 and I of FIG.
The same components as those of C1 will be described with the same reference numerals.

Reference numeral 20 generally indicates the IC of the present invention. The IC chip 5 is the die pad 1 of the lead frame 10.
Inner leads 13 die-bonded to 2 and depressed as usual with each electrode of this IC chip 5.
The tip end portion 13a of is connected by the wire 7.

Further, the mold resin M is flown within the range surrounded by the two-dot chain line L shown in FIG. 2 to seal the IC chip 5 and the inner leads 13. At this time, the thickness of the resin Ma above the IC chip 5 and the resin M below the die pad 12
The outer lead 14 is sealed so that it has the same thickness as that of b, and each outer lead 14 is led out to the outside from the central portion of the thickness of the entire molding resin M (package).

After the sealing resin M is hardened, the molding resin M is burred, and at the same time, the suspension 16, the tie bar 17, and the side rails 18 are separated from the stay 15, and a plurality of outer leads 14 are provided according to the usage. If you bend it,
The IC 20 of the present invention is obtained. In the case of FIG. 1, it was bent to the side where the die pad 12 is present.

Thus, the tip portion 1 of the inner lead 13 is
Since the bonding surface is lowered by depressing 3a from the other portion 13c, the wire 7 can be pulled downward during wire bonding, and accordingly, the loop portion 7 of the wire 7 can be pulled down.
The height of a can be suppressed low.

The depress of the tip portion 13a of the inner lead 13 can be formed by a normal press. The depth of the depression is determined in consideration of the thickness of the IC chip 5 and the total thickness of the IC 20 when completed, but is about 0.05 mm to 0.1 mm.

Next, the tip portion 1 of the inner lead 13
A second embodiment, which is a modification of 3a, is shown in FIG. In this embodiment, only the tip portions 113a of the inner leads 13 are half-etched to form a depressed structure. This etching amount can be changed as needed, but if the thickness of the lead frame 10 is 0.1 mm,
Can be etched to about 0.07 mm. Since the position of the bonding point of the inner lead 13 can be further lowered in this way, the height of the loop portion 7a of the wire 7 can be lowered.

Further, the inner lead 1 shown in FIG.
A third embodiment, which is a modification of the tip portion 13a of No. 3, is shown in FIG. In this embodiment, each tip portion 13a of the inner lead 13 is half-etched while leaving its edge to form a recess 13d. Therefore, the same effect as in the second embodiment can be obtained, and the wire flow generated by the resin flow at the time of resin sealing can be suppressed.

Furthermore, a fourth embodiment which is a modification of the tip portion 13a of the inner lead 13 shown in FIG. 3 is shown in FIG.
It was shown to. In this embodiment, half-etching is performed leaving the edges so that the recesses 13e are formed so that the vicinity of the bonding point of each tip 13a is widened. Therefore,
Wire bonding becomes easy.

[0024]

As described above, according to the lead frame of the present invention and the resin-sealed semiconductor device using the same, the height of the loop portion of the wire can be reduced, and therefore,
A thin resin-encapsulated semiconductor device in which the wire is not exposed from the encapsulating resin can be obtained using existing manufacturing equipment.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a resin-encapsulated semiconductor device that is an embodiment of the present invention.

FIG. 2 is a plan view of a lead frame that is a first embodiment of the present invention.

FIG. 3 is a partially enlarged perspective view of a tip portion of an inner lead which is a constituent element of the lead frame shown in FIG.

FIG. 4 is a partially enlarged perspective view of a tip portion of an inner lead that is a constituent element of a lead frame that is a second embodiment of the present invention.

FIG. 5 is a partially enlarged perspective view of a tip portion of an inner lead which is a constituent element of a lead frame which is a third embodiment of the present invention.

FIG. 6 is a partially enlarged perspective view of a tip portion of an inner lead which is a constituent element of a lead frame which is a fourth embodiment of the present invention.

FIG. 7 is a cross-sectional view of a resin-sealed semiconductor device according to a conventional technique.

[Explanation of reference numerals] 5 semiconductor chip (IC chip) 7 wire 7a loop portion 10 lead frame 12 die pad 13 inner lead 13a (inner lead) tip portion 13b (inner lead) bent portion 13c (inner lead) other portion 13d recess 13e recess 14 outer lead 15 stay 16 suspension 20 resin-sealed semiconductor device M mold resin

Claims (4)

[Claims] 1. A lead frame comprising at least a plurality of inner leads for leading out a plurality of electrodes of a semiconductor chip to the outside and outer leads corresponding to the inner leads, wherein each tip of the inner leads is depressed. A lead frame characterized by that. 2. The lead frame according to claim 1, wherein the thickness of the tip portion of the inner lead is smaller than the thickness of the other inner lead portions. 3. The lead frame according to claim 1, wherein the thickness of a part of the tip portion of the inner lead is thinner than the thickness of the other inner leads. 4. A semiconductor chip is arranged in a central portion, and a plurality of inner leads and outer leads corresponding to these are arranged in the peripheral portion of the semiconductor chip so as to correspond to a plurality of electrodes of the semiconductor chip. The top surface of the tip is located lower than the tops of other parts of the inner lead, and the electrodes are connected to the corresponding tip of the inner lead to seal the semiconductor chip and the inner lead with resin. Stop, and resin-encapsulate so that the thickness of the resin existing above the semiconductor chip and the thickness of the molding resin present below are equal, and the outer lead is from the center of the thickness of the sealing resin A resin-encapsulated semiconductor device, which is derived and bent outside the resin in a desired shape.