JP2621814B2 - Resin-sealed semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a resin-encapsulated semiconductor device and a lead frame, and more particularly to a method for manufacturing a semiconductor chip mounted and bonded on an island.
Manufacture of a resin-sealed semiconductor device having a structure sealed with resin by transfer molding using a mold having a gate at a suspension pin for island support, and a lead frame used for manufacturing the resin-sealed semiconductor device About the method.

[0002]

2. Description of the Related Art FIG. 4 shows an example of this type of conventional resin-encapsulated semiconductor device (hereinafter referred to as LSI). FIG.
4A is a cross-sectional view, and is a diagram showing a cross-sectional structure taken along the line Aa in the perspective plan view shown in FIG. FIG.
Referring to (a) and (b), a semiconductor chip 1 is mounted on an island 4 at the center of a metal lead frame, and bonding pads (not shown) on the chip 1 and internal leads 8 of the lead frame are formed. They are electrically connected by wire bonding (the wires are not shown). Each of the four corners of Island 4 has a hanging pin 2
Are connected. The suspension pins 2 are connected to an outer frame portion (not shown) of the lead frame and support the island 4 during the manufacturing process. The chip 1, the island 4, the suspension pins 2, the bonding wires, and the internal leads 8 are sealed and covered with a resin 7 for sealing and covering them. The resin 7 is formed by transfer molding using a thermosetting resin.

Here, in connection with the present invention, a process of injecting a sealing resin by transfer molding will be described with reference to FIG. In the resin sealing step, first, the lead frame after mounting and bonding is removed from the upper and lower molds 5.
a, 5b and the external leads 9 of the lead frame.
The region (FIG. 4A) is clamped (FIG. 5A). Next, the molten resin 7 is injected from the gate of the mold (FIG. 5B). In this case, the position and the shape of the gate for injecting the molten resin are usually designed such that the resin 7 is injected along the suspension pins 2 and into the cavity from the lower mold 5b (FIG. 4 ( a) and FIG.
(B)). After the resin injection is completed, the chip 1 is removed from the mold, and cut into individual pieces by tie bar cutting and lead cutting. Finally, the external leads 9 of the lead frame are formed into a predetermined shape to complete a resin-sealed LSI.

[0004]

As described above, in the transfer molding process of the resin-sealed LSI, the molten resin 7 is usually injected from the gate provided on the suspension pin 2 of the lower mold 5b, Move along the hanging pin 2 and the mold 5
a, 5b are filled. For this reason, in the conventional resin-sealed LSI, the so-called island shift is likely to cause movement or deformation of the island 4 from the design position, or warpage of the LSI outer shape caused by such island shift. The reason will be described below.

Referring again to FIG. 5 showing a sealing resin forming process by transfer molding, since the molten resin 7 is filled from the lower mold 5b, the suspending pins 2 are attached to the resin 7 pressed into the cavity. There is a difference in the filling amount between the top and bottom of the sandwich. As a result, the hanging pin 2 receives an upward force due to the injection pressure of the resin, and is lifted upward and deformed as shown in FIG. 5B. When the filling of the resin 7 proceeds further, as shown in FIG. 5C, the molten resin 7 below the hanging pin reaches the island 4 and the large island 4 itself receives pressure from below. The deformation of the suspension pin 2 and the displacement of the island 4 are further increased (FIG. 5D). Once such an island shift occurs, the LSI after removal from the mold and cooling,
Due to the shrinkage of the sealing resin 7 and the elasticity of the deformed metal lead frame, warpage occurs as shown in the side view of FIG. 6A, and this LSI has an outer shape defect.

When the external lead is formed in the next step, as schematically shown in the side view of FIG. 6B, the LSI is clamped by the lead forming die 10 and the external lead is forcibly flattened. Because the leads are molded,
Even a warped LSI as shown in (a) can perform a predetermined lead forming operation. However, when the LSI is warped, when the LSI is removed from the lead molding die, as shown in FIG. 6C, the LSI returns to the original warped state, and eventually, a predetermined lead shape cannot be obtained. .

For the purpose of suppressing the island shift at the time of the transfer molding as described above, the resin-encapsulated LSI is formed by bending the hanging pins 2 up and down as shown in a sectional view of FIG. Also, there is known an LSI having a structure in which the mold dies 5a and 5b are in close contact with the inner walls. However, even in this structure, the molten resin 7 is
Due to the injection from b, there is a difference between the upper and lower resin filling amounts with the hanging pin 2 interposed therebetween, so that an upward force as shown by a thick arrow in the figure is applied to the hanging pin 2. As a result, the deformation of the suspension pins 2 and the positional fluctuation of the islands 4 accompanying the deformation also occur.

Accordingly, the present invention provides a resin seal having a structure in which a semiconductor chip mounted and bonded on an island is resin-sealed by transfer molding using a mold having a gate at a suspension pin for supporting the island. It is an object of the present invention to suppress the deformation of the suspension pin generated during transfer molding and the fluctuation of the island position caused by the transfer in the stop LSI.

[0009]

According to the present invention, there is provided a resin-encapsulated semiconductor device comprising: an island for mounting a semiconductor chip; a suspension pin connected to the island; In the semiconductor device, the suspending pin has a rectangular quadrilateral opening, and a flat surface of the sealing exterior resin extending from one side of the opening to reach one flat surface of the sealing exterior resin. At least one metal piece that bends along the opening and protrudes from one side of the opening to extend to the other flat surface of the encapsulation exterior resin and bends along the flat surface of the encapsulation exterior resin At least one metal piece is provided.

[0010]

In the resin-sealed semiconductor device of the present invention, the suspension pin has an opening. The molten resin press-fitted from the lower mold at the time of transfer molding passes through the opening and fills the lower surface of the suspension pin and almost simultaneously fills the upper surface. Therefore, the difference in the filling amount of the molten resin between the upper and lower portions of the suspension pin is smaller than that in the related art.

In the present invention, when forming the above-mentioned opening, a part of the portion to be opened is left in a comb-like shape, and the comb-like metal pieces are bent up or down to form a mold metal. Adhere to the mold inner wall. Since the suspension pins and islands are supported by the suspension pins and the upper and lower molds that are in close contact with the inner wall of the mold, even if there is a difference in the resin filling amount above and below the suspension pins, deformation of the suspension pins and island Is small.

[0012]

Next, a preferred embodiment of the present invention will be described with reference to the drawings. FIG. 1A is a sectional view of a first embodiment of the present invention. FIG. 1B is a partially enlarged plan view of the suspension pin used in this embodiment. Referring to FIG. 1, in the present embodiment, a comb-shaped slit 6 as shown in FIG. 1B is formed in advance in a portion of a suspension pin 2 at the time of manufacturing a lead frame. Next, a part of the hanging pin left in the shape of a comb is bent upward or downward by press working,
As shown in FIG. 1 (a), the upper and lower mold dies are in close contact with the inner walls. Hanging pin 2 after processing in this way
Will have a rectangular opening. The protruding metal pieces 3a and 3b bent upward or downward by the above-mentioned press work act as deformation-preventing support members for preventing deformation of suspension pins and fluctuation of island positions during transfer molding. The above-described press working is performed by the same method as when down-set processing is performed on the island portion. That is, the lead frame in which the slits 6 are formed in the suspension pins 2 by etching or press working is placed on a stage for performing press working, and first, one lower supporting member 3b is pressed. If the lead frame has a downset in the island 4 portion, it is preferable that the step is performed simultaneously with the first step of pressing the support member 3b. Next, the other upper supporting member 3a is pressed. In this case, press working is performed by using another stage having a clearance space for preventing deformation of the previously pressed portion. There is a need to do.

Using the lead frame thus obtained, the chip 1 is mounted on the island 4 with a conductive adhesive such as a silver paste. Thereafter, the chip 1 and the internal leads are electrically connected by a bonding wire such as a gold wire, and transfer molding is performed.

In the transfer molding, molding conditions such as the shape of the mold and the injection pressure of the resin may be the same as those in the prior art. Referring to FIG. 2, which shows the progress of the transfer molding step by step in this embodiment, the lead frame on which the chip 1 is mounted and bonded is connected to the mold 5a,
5b, and projecting-like supporting members 3a, 3b formed by press working before and after are formed by upper and lower mold dies 5a, 5b.
b (FIG. 2A). Next, the molten sealing resin 7 is pressed into the cavity from the lower mold 5b. In this case, since the suspension pin 2 has an opening, the molten resin 7 injected from the lower die 5b passes through the opening and is almost simultaneously injected with the lower die 5b into the upper die 5a.
Also flows into. Therefore, unlike the transfer molding in the conventional resin-encapsulated LSI manufacturing, the suspension pins 2
There is no difference in filling of the molten resin 7 above and below, and no upward force is applied to the suspension pins 2 (FIG. 2B). Moreover,
The hanging pins 2 and the islands 4 are provided with the projecting support members 3.
a, 3b and the upper and lower molds 5a, 5b, the island 4 can be lifted during resin filling.
No (FIG. 2 (c)). Even after the molten resin 7 is completely filled in the cavity, the position of the island 4 maintains the same design position (FIG. 2A) as when it was set in the mold at the beginning of this step. The thickness of the upper and lower sealing resins 7 sandwiching the chip 1 and the island 4 becomes uniform as designed (FIG. 2D). Therefore, when the LSI is removed from the molds 5a and 5b and cooled,
There is no warping.

According to the present embodiment, the position variation amount of the island (maximum amount of displacement from the flat position of the island. Indicated by d ₁ in FIG. 5 (d)), conventional 200~400μm
Was reduced to almost 0 μm. Thus, with respect to warping of the LSI (indicated by d ₂ in shift amount from the exterior resin bottom surface of the design position. FIG. 6 (a)), those which is conventionally 30 to 60 m, approximately 0μm i.e. almost flat state I was able to. As a result, there was no influence on the coplanarity when the external lead was formed, and a uniform lead flat portion was obtained.

Next, a second embodiment of the present invention will be described. FIG. 3A is a sectional view of a second embodiment of the present invention, and FIG. 3B is a partially enlarged plan view of a suspension pin used in this embodiment. Referring to FIG. 3, in the present embodiment, at the time of manufacturing the lead frame, a slit 6 having a shape obtained by inverting the shape of the slit 6 in the first embodiment (FIG. 1B) is formed on the suspension pin 2. Keep it. Then, in the same manner as in the first embodiment, the metal piece remaining in the shape of the comb of the hanging pin 2 having the slit 6 formed thereon is removed from the molding die 5.
a, 5b Pressed into a shape that closely adheres to the inner wall.
By doing so, an opening similar to that of the first embodiment can be formed in the suspension pin 2. However, in this embodiment, the support members 3a and 3b have a convex shape facing outward from the chip 1. Using the lead frame thus obtained, a chip 1
Is mounted on the island 4 via a conductive adhesive such as a silver paste, and the chip 1 and the internal lead are wire-bonded with a thin metal wire, followed by transfer molding.

Due to the opening provided in the suspension pin 2, there is no difference between the upper and lower mold dies 5a, 5b when the molten resin 7 is filled in the transfer molding. Further, since the hanging pins 2 and the islands 4 are supported by the projecting support members 3a and 3b and the mold, the position of the islands does not change. Therefore, even after the resin filling is completed, the thickness of the upper and lower sealing resins sandwiching the chip 1 and the island 4 becomes uniform, and the LSI does not warp when the LSI is removed from the mold and cooled.

[0018]

As described above, according to the present invention, a comb-shaped slit is provided in a suspension pin portion of a lead frame,
By bending the tooth-shaped metal piece of the remaining comb upward or downward, a rectangular opening is provided in the hanging pin, and the bent metal piece is placed on the upper and lower inner walls of the mold during transfer molding. We are trying to adhere.

Thus, according to the present invention, the resin sealing type L
When filling the molten resin in the transfer molding process of SI, the difference in filling amount of the molten resin between the upper and lower portions of the suspending pin is the same, and the suspending pin and the island are supported by the metal piece and the mold. In addition, the suspension pin is not deformed and the position of the island is not changed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a first embodiment of the present invention and a partially enlarged plan view of a suspension pin used in the first embodiment.

FIG. 2 is a cross-sectional view showing stepwise progress of resin filling in transfer molding in the first embodiment.

FIG. 3 is a sectional view of a second embodiment of the present invention and a partially enlarged plan view of a suspension pin used in this embodiment.

FIG. 4 is a schematic plan view of a lead frame used in a conventional resin-sealed LSI, and a cross-sectional view of an example of a resin-sealed LSI using the same.

FIG. 5 is a sectional view showing stepwise progress of resin filling in transfer molding in the conventional resin-sealed LSI shown in FIG.

FIG. 6 is a side view showing a warped state in the resin-sealed LSI.

FIG. 7 is a sectional view of another example of a conventional resin-sealed LSI.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Chip 2 Hanging pin 3a, 3b Support member 4 Island 5a, 5b Mold die 6 Slit 7 Sealing resin 8 Internal lead 9 External lead 10 Lead molding die

Claims (3)

(57) [Claims] 1. A resin-encapsulated semiconductor device including an island for mounting a semiconductor chip, a suspending pin connected to the island, and a resin for sealing and encapsulation, wherein the suspending pin has a rectangular opening. And at least one or more metal pieces that protrude from one side of the opening and extend to reach one flat surface of the sealing exterior resin and bend along the flat surface of the sealing exterior resin; and At least one metal piece that protrudes from one side of the portion and extends to reach the other flat surface of the sealing exterior resin and bends along the flat surface of the sealing exterior resin. Resin-encapsulated semiconductor device. 2. The resin-encapsulated semiconductor device according to claim 1, wherein said two kinds of metal pieces both project from a side of said opening closer to said semiconductor chip. Type semiconductor device. 3. The resin-encapsulated semiconductor device according to claim 1, wherein said two kinds of metal pieces both protrude from a side of said opening farther from said semiconductor chip. Type semiconductor device.