JP3227953B2 - Lead frame and semiconductor device using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-encapsulated semiconductor device (hereinafter, simply referred to as an "IC chip") in which an electronic circuit is integrated and formed by a transfer molding method. Simply referred to as “IC”) and a method for producing the same.

[0002]

2. Description of the Related Art In a conventional IC resin sealing method, an IC chip mounted and fixed on a lead frame is resin-molded by a transfer molding method using a molding die.
The IC chip in the cavity of the molding die may move up and down or tilt from a designed position in the cavity due to the pressure of the molten resin injected into the cavity, or a so-called stay shift may occur.

In particular, in recent years, the degree of integration of electronic circuits has increased,
As the area of the IC chip increases, the number of pins of the IC also increases, and the pitch between the outer leads also decreases. As a result, the width of the suspending leads for suspending the inner leads and the die pad becomes thinner and longer. It has become to.

Further, in order to make an IC ultra-thin, a floating chip which does not use a gold wire by forming a bump on an inner lead, using a lead frame without a die pad, connecting the bump to an electrode pad of an IC chip, and using a bump. An IC of a structure in which a TAB lead having a copper film lead formed on a surface thereof based on a polyimide film is used in place of a lead frame, and an inner lead of the TAB lead is directly connected to an electrode pad of an IC chip.
There is C.

In such a structure, the IC chip is liable to cause a stay shift even with a small resin pressure. As a result, the IC package is warped, the IC chip, the inner lead, or the gold wire 13 is exposed to the outside, and corrosion due to invasion of moisture, short-circuit of the gold wire, or disconnection of the gold wire is caused.
Then, a change in characteristics due to external light occurs.

In order to prevent the stay shift from occurring, the present inventors have conducted various studies, for example, Japanese Patent Application No. 5-2 filed on Oct. 25, 1993 by the present applicant.
No. 66378, entitled "Resin-sealed semiconductor device and its manufacturing method".

That is, according to the present invention, in the case of a lead frame having a die pad, only on the front surface of the IC chip or on the back surface of the die pad. Forming a plurality of protrusions having a practical minimum height only on the front surface or on the back surface of the IC chip, and
A lead frame on which the IC chip is mounted is disposed at a predetermined position in a cavity of a transfer mold, and the upper and lower molds are fastened to control the vertical movement of the IC chip in the cavity by the protrusion. In such a state, the molten resin is injected into the cavity to seal the IC chip to obtain an IC, thereby solving the stay shift problem and the like.

[0008]

However, in the IC of the invention of the patent application, a plurality of projections must be formed on the surface of an IC chip or the like, and the number of steps for forming the projections increases. There is a drawback in that a device for forming the projection is required, and the formation of the projection itself requires a high level of technology.

[0009]

Accordingly, in the present invention,
A plurality of inner leads, outer leads formed corresponding to these inner leads, and a plurality of IC chip holders formed on substantially the same surface as these inner leads are formed, and a die frame without a die pad is formed. A plurality of electrodes formed on the IC chip and the respective inner leads are connected to each other;
The C chip holder is mounted so as to be bonded to the dummy pad of the semiconductor chip via the intermediate conductive layer, and the IC chip in such a state is placed in the cavity of the transfer mold. Injecting a molten resin into the cavity and sealing the IC chip with a resin while pressing the IC chip while suppressing the movement of the IC chip by the molten resin. Was solved.

[0010]

Therefore, when the IC chip holder is formed on the inner lead or the outer lead, the inner lead and the IC chip holder are patterned on the upper conductive layer, and the outer lead is patterned on the surface of the lower conductive layer. Leads, IC chip holders, and outer leads can be formed simultaneously from both sides.
Since the IC chip can be reliably fixed by holding down the chip, an IC having an ultra-thin structure can be manufactured with high accuracy and at low cost.

[0011]

1 to 6, a lead frame according to the present invention, a semiconductor device using the same and a method for manufacturing the lead frame will be described. FIG. 1 shows an embodiment of a lead frame according to the present invention. FIG. 1A is a schematic plan view showing a state in which an IC chip is mounted and fixed on the lead frame, and FIG. A cross-sectional view of the inner lead and the outer lead on the line, and FIG. C is an enlarged plan view of the IC chip holder indicated by an arrow B in FIG. A, and FIG. 2 is an IC chip holder of the lead frame shown in FIG.
FIG. 3 is an enlarged plan view of a main part showing a first structure for suppressing the movement of the C chip, and FIG.
FIG. 9 is an enlarged plan view of a main part showing a second structure for suppressing the movement of the IC chip by holding down the C chip.

FIG. 4 shows the structure of the IC shown in FIG. 3 mounted and fixed on the lead frame of the present invention.
FIG. 4A is a view for explaining a first resin sealing method of a chip, FIG. 4A is a cross-sectional view showing a state where the chip is mounted on a transfer mold, and FIG. 5B is taken out from the mold. FIG. 5 is a cross-sectional view of the IC in a state, and FIG. 5 is a view for explaining a second resin sealing method of the IC chip mounted and fixed on the lead frame according to the present invention with the structure shown in FIG. FIG. 2A is a cross-sectional view showing a state where the IC is mounted on a transfer mold, and FIG. 2B is a cross-sectional view of the IC taken out of the mold.
FIG. 6 shows the third state of the IC chip mounted and fixed on the lead frame of the present invention in the structure shown in FIG.
FIG. A is a cross-sectional view showing a state in which the mold is mounted on a transfer mold, and FIG. B is a cavity surface of a lower mold of the mold. And FIG. C is a sectional view of the IC taken out of the molding die.

First, an embodiment of a lead frame according to the present invention will be described with reference to FIG. The lead frame L shown in FIG. 1 is made of Cu, Al, and Cu disclosed in Japanese Unexamined Patent Application Publication No. 5-90350 “Semiconductor Device” filed by the present applicant and published on April 9, 1993. The structure is basically the same as the structure of a lead frame formed using a three-layer clad material composed of a combination or the like. The lead frame L is a lead frame having the advantages of the conventional lead frame and the advantages of the TAB lead, in which the strength of the outer lead of the TAB lead is improved.

The lead frame L has an opening 7 in the center where the IC chip S is placed. That is, the lead frame L is a die padless type.
When the front end faces the opening 7 and the IC chip S is placed in the opening 7, a plurality of IC chips S are extended so as to come on a plurality of electrode pads 8 formed on the surface of the IC chip S. It comprises an inner lead 1, outer leads 2 formed corresponding to these inner leads, and a plurality of IC chip holders 5 formed on substantially the same surface as the inner leads 1.

The IC chip holder 5 desirably suppresses a portion of the IC chip S where the electrode pads 8 are not formed. In this embodiment, the IC chip holder 5 faces the opening 7 from the frame 6 side, and is provided on both sides of the IC chip S. , And at positions where the vicinity of both ends can be suppressed (FIGS. A and C). A plurality of holes 9 are formed in the IC chip holder 5 of this embodiment so that the molten resin in the case of sealing the IC chip S with resin can flow freely.

The manufacture of the lead frame L can be performed by the method disclosed in the above publication.
That is, for example, it is manufactured using a three-layer clad plate composed of a Cu layer having a thickness of 30 μm, an Al layer having a thickness of 50 μm, and a Cu layer having a thickness of 125 μm as a base material. Cu with a thickness of 30 μm
The inner lead 1 and the IC chip holder 5 are patterned on the surface of the layer, and the outer leads 2 are patterned on the surface of the Cu layer having a thickness of 125 μm.
Alternatively, by sequentially etching from one surface, a plurality of inner leads 1 and IC chip holders 5 and a plurality of outer leads 2 corresponding to the inner leads 1 can be formed.

In this case, the Al layer 3 serves as an etching stop layer. An unnecessary portion of the Al layer 3 is removed, and an Al bump 4 having a thickness of about 50 μm is formed at the tip of each inner lead 1. . Further, the inner leads 1 and the outer leads 2 are connected by the Al layer 3 (FIG. 2B).

When the IC chip S is placed in the opening 7 of the lead frame L having such a structure, a plurality of IC chip holders 5 are provided on both sides of the IC chip S, as shown in FIG. The bumps 4 formed on both ends and formed on the tips of the plurality of inner leads 1 are located on the respective electrode pads 8 of the IC chip S. Therefore, the IC chip S can be fixed to the lead frame L by bonding each bump 4 to the electrode pad 8.

As shown in FIG. 2, the state of the IC chip retainer 5 in this state is such that the tip of the IC chip retainer 5 hangs over the periphery of the electronic circuit forming surface of the IC chip S and suppresses that portion. It is in the state that it was in. As shown in FIG. 3, an Al bump 10 similar to the bump 4 of the inner lead 1 is formed at the tip of the IC chip holder 5, while the dummy pad 11 is also formed on the surface of the IC chip S.
Is formed, and by bonding these two, the IC is further increased.
The chip S can be firmly fixed to the lead frame L.

Next, a resin sealing method of the IC chip S mounted and fixed on the lead frame L will be described with reference to FIGS. The first resin sealing method will be described with reference to FIG. In FIG. 1A, reference numeral 20 denotes a transfer molding molding die, and the molding die 20 includes an upper die 21 and a lower die 22. Upper mold 2
The IC chip S, the inner lead 1, the IC chip holder 5, and a part of the frame 6 are accommodated in a cavity formed by the first cavity 23 and the cavity 24 of the lower mold 22, and the upper and lower molds 21, 22 are fastened. Then, the molten resin is injected. After curing of the molten resin, the molding die 20
If the C chip S is taken out, as shown in FIG.
The IC 30 in which the periphery of the chip S is sealed with the sealing resin M can be obtained. As shown by the dotted line T, the frame 6 is not included in the area to be sealed with the resin.
The chip S can be sealed with a resin.

In this embodiment, the IC chip S is a lower mold 2
Since it is arranged in the molding die 20 in a state of being floated from the cavity surface of No. 2, it is easily affected by the pressure of the flowing molten resin.
Therefore, in this case, it is preferable that the structure of the IC chip holder 5 with respect to the IC chip S use a structure in which the IC chip S is firmly fixed to the lead frame L as shown in FIG.

FIG. 5 shows a second resin sealing method. In FIG. 1A, in this resin sealing method, the IC chip S is placed so that the back surface of the IC chip S is in contact with the cavity surface 22A of the lower mold 22, and the IC chip holder 5 holds the IC chip S from above on the cavity surface 22a. The upper and lower dies 21, 22 are fastened in such a state that they are held down. When the molten resin is injected, the floating of the IC chip S can be suppressed by the IC chip retainer 5 even if the molten resin attempts to lift the IC chip S upward.

In this resin sealing method, the back surface of the IC chip S is supported by the cavity surface 22a.
As shown in (1), the one in which the IC chip S is fixed to the lead frame L with only the inner lead 1 may be used. After curing of the molten resin, the molding die 20
If the C chip S is taken out, as shown in FIG.
An IC 31 in which one surface of the chip S is sealed with the sealing resin M can be obtained.

FIG. 6 shows a third resin sealing method. On the cavity surface 22a of the lower die 22A used for the molding die 20A, columnar pins 25 capable of supporting four corners (B in the drawing) on the back surface of the IC chip S are implanted.
These pins 25 position the IC chip S in the thickness direction. Using the lower mold 22A having such a structure, FIG.
As shown in the figure, the IC chip S is placed on these pins 25, and the IC chip S is fixed to the pins 25 from above by the IC chip holder 5, and the molten resin is filled in the cavity. inject. After curing the molten resin,
If the IC chip S is taken out from the molding die 20A, the same as FIG.
As shown in (2), an IC 32 having a shape in which the pin mark 26 is formed on the sealing resin M on the back surface of the IC chip S can be obtained.

In the above description, 3 is used as the lead frame.
Although the example in which the layer clad material is used as the base material is illustrated, the lead frame of the present invention is not limited to this structure. It goes without saying that the present invention can also be applied to a lead frame formed from a single metal plate that has been generally used. In this case, the IC chip holder can be formed at the same time when the inner leads and the outer leads are formed by etching or punching.

[0026]

As described above, the lead frame of the present invention is provided with an IC chip holder, and the Al chip formed on the IC chip holder and the tip thereof is formed simultaneously with the formation of the inner lead and the outer lead. Since the IC chips can be reliably suppressed or fixed by holding down the IC chips, an IC having an ultra-thin structure can be manufactured with high accuracy and at low cost. In particular, in the lead frame of the embodiment shown in FIG. 1, since the inner lead and the outer lead are in a micro-joined state, this portion is easily affected by the molten resin pressure. Since the movement of the IC chip is suppressed by the IC chip holding, there are a number of excellent effects, such as damage to that part can be reduced or eliminated.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a lead frame according to the present invention. FIG. 1A is a schematic plan view showing a state in which an IC chip is mounted and fixed on the lead frame, and FIG.
A sectional view of the inner lead and the outer lead on the line -A, and FIG. C is an enlarged plan view of the IC chip holder indicated by the arrow B in FIG.

FIG. 2 is an enlarged plan view of a main part showing a first structure for suppressing the movement of the IC chip by holding down the IC chip of the lead frame shown in FIG. 1;

FIG. 3 is an enlarged plan view of a main part showing a second structure for suppressing the movement of the IC chip by holding down the IC chip of the lead frame shown in FIG. 1;

FIG. 4 is a view for explaining a first resin sealing method of the IC chip mounted and fixed on the lead frame of the present invention with the structure shown in FIG. 3, and FIG. FIG. 2 is a cross-sectional view showing a state where the IC is mounted on a molding die, and FIG. 2B is a cross-sectional view of the IC taken out of the molding die.

FIG. 5 is a view for explaining a second resin sealing method of the IC chip mounted and fixed on the lead frame of the present invention with the structure shown in FIG. 2, and FIG. FIG. 2 is a cross-sectional view showing a state where the IC is mounted on a molding die, and FIG. 2B is a cross-sectional view of the IC taken out of the molding die.

FIG. 6 is a view for explaining a third resin sealing method of the IC chip mounted and fixed on the lead frame according to the present invention with the structure shown in FIG. 2, and FIG. It is sectional drawing which showed the state attached to the molding die for molding, FIG. B is the top view which showed the cavity surface of the lower die of the molding die, and FIG. C was taken out from the molding die. It is sectional drawing of IC of a state.

[Explanation of symbols]

 S IC chip L Lead frame M Sealing resin 1 Inner lead 2 Outer lead 3 Al layer 4 Bump 5 IC chip holder 6 Frame 7 Opening 8 Electrode pad 9 Hole 10 Al bump 11 Dummy pad 20 Mold 20A Mold 21 Upper mold 22 Lower mold 22A Lower mold 22a Cavity surface 23 Cavity 24 Cavity 25 Pin 26 Pin mark 30 IC of the first embodiment 31 IC of the second embodiment 32 IC of the third embodiment

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-57255 (JP, A) JP-A-4-7848 (JP, A) JP-A-2-278857 (JP, A) 23088 (JP, Y2) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 23/50

Claims (2)

(57) [Claims] 1. A laminated clad material comprising at least three layers of an upper conductive layer, an intermediate conductive layer, and a lower conductive layer,
A die padless semiconductor device lead frame having a plurality of inner leads, outer leads formed with respect to the inner leads, and a plurality of semiconductor chip holders formed on substantially the same surface as the inner leads, A plurality of the outer leads are formed in the lower conductive layer, and the inner leads and the plurality of semiconductor chip holders corresponding to the respective outer leads are formed in the upper conductive layer, and the inner leads and the semiconductor chip holders are formed. Are connected to the outer leads via the intermediate conductive layer. 2. A resin-encapsulated semiconductor device comprising a semiconductor chip mounted on a lead frame according to claim 1, wherein an inner lead of the lead frame is connected to an electrode formed on the semiconductor chip. A resin-encapsulated semiconductor device, wherein a semiconductor chip holder formed on a lead frame is resin-encapsulated while being bonded to a dummy pad of the semiconductor chip via the intermediate conductive layer.