JPH0794651A - Fabrication of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a method for fabricating a semiconductor device in which deformation of a lead frame formed by electroforming can be prevented effectively. CONSTITUTION:A semiconductor chip 26 is mounted on a lead frame 12 formed on a mother die 10 without separating therefrom. A layer 38 for sealing the resin sealed part including the semiconductor chip 26 is then formed and the lead frame 12 is reinforced before it is separated from the mother die.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly, after mounting a semiconductor chip on a lead frame formed by an electroforming method, a resin-sealed portion including the semiconductor chip is sealed with a resin. The present invention relates to a method for manufacturing a semiconductor device in which the semiconductor device is stopped to manufacture a semiconductor device.

[0002]

2. Description of the Related Art A lead frame for a semiconductor device is generally formed by pressing or etching a metal material. However, stamping,
In any of the etching processes, the minimum punching width that can be stably processed is about the thickness of the metal material used as the raw material, and there is a limit to forming a fine pattern with a constant material thickness. On the other hand, manufacturing of a lead frame by an electroforming method has been proposed in, for example, Japanese Patent Publication No. 48-39867. In this electroforming method, as shown in FIG. 5, first, a matrix 1 made of a conductive material such as stainless steel is used.
The resist 102 formed by coating or adhering on [00] is exposed to a pattern of a desired shape [FIG. 5 (b)] and then developed to form a resist pattern 104 [FIG. 5 (a)]. (C)]. Then, this resist pattern 10
4 is used as a mask, the leads 106 are formed by plating in the gaps between the resist patterns where the surface of the mother die 100 is exposed [FIG. 5 (d)], and then the resist pattern 104 is formed.
Then, the lead 106 is peeled off from the mother die 100 to obtain a lead frame [FIG. 5 (e)]. The obtained lead frame is further plated if necessary. After removing the resist pattern 104 on the mother die 100, surface polishing may be performed to make the thickness of the leads 106 uniform.

[0003]

According to the electroforming method shown in FIG. 5, a lead frame having a rectangular cross section and an extremely fine pattern can be manufactured with good accuracy. However, when the lead 106 obtained is peeled from the matrix 100 when the lead frame is manufactured by the electroforming method of FIG. 5, the lead 106 is easily deformed. It was also found that the lead frame obtained by peeling from the mother die 100 is easily deformed in a post process such as a plating process. The deformation of the lead frame obtained by the electroforming method becomes more remarkable as the pattern of the lead frame becomes finer. by the way,
In the future, with the high integration of semiconductor chips and the miniaturization of semiconductor devices, it is required to increase the pin count and density of the lead frame. Therefore, there is a demand for means for preventing deformation of the lead frame formed by the electroforming method that can form a fine pattern. Therefore, an object of the present invention is to propose a method of manufacturing a semiconductor device, which can effectively prevent deformation of a lead frame formed by an electroforming method.

[0004]

In order to achieve the above-mentioned object, the inventor of the present invention uses an electroforming method on a mother die used for one of the molds constituting a resin-sealing die for resin-sealing. The semiconductor chip is mounted while mounting the formed lead frame on the mother die without peeling it off from the mother die,
The lead frame can be reinforced by resin-sealing the resin-sealed portion including the mounted semiconductor chip, and it was considered that it is effective to peel the lead frame from the mother die after resin-sealing. Has reached the present invention. That is, according to the present invention, when a semiconductor chip is mounted on a lead frame formed by an electroforming method, and a resin-sealed portion including the semiconductor chip is resin-sealed to manufacture a semiconductor device, the resin-sealed Forming a lead frame on one of the molds used in one of the molds forming the resin-sealed mold, and forming the lead frame on the master mold without peeling from the master mold. A semiconductor chip is mounted on the frame, and then the other mold forming the resin-sealing mold is brought into contact with the mother mold on which the lead frame is formed, and the resin formed by the other mold and the mother mold. A resin sealing portion including the semiconductor chip is inserted into the cavity of the sealing mold, and then a sealing resin layer is formed by injecting a sealing resin into the cavity. The lead frame reinforced Te lies in a method of manufacturing a semiconductor device, characterized by peeling from the mold.

In the present invention having such a structure, the inner lead can be insulated and sealed by forming an insulating layer on the exposed surface of the inner lead of the lead frame separated from the mother die. Further, by filling a resin leakage preventing filler between the leads of the outer lead formed on the mother die that abuts the other die, the sealing resin does not leak between the leads during resin encapsulation. You can prevent it from coming out. In addition, an insulating layer is formed on the exposed surface of the inner lead of the lead frame separated from the mother die, and a bump protruding from the insulating layer is provided on the inner lead surface so as to mount the obtained semiconductor device. It is possible to eliminate the need for an outer lead that can be easily formed and that does not protrude from the sealing resin layer and cannot be reinforced by the sealing resin layer. Alternatively, the degree of freedom of the bump formation position can be improved by joining the circuit board to the exposed surface of the inner lead of the lead frame separated from the mother die.

[0006]

In the present invention, when a semiconductor chip or the like is mounted on the lead frame formed by the electroforming method, the lead frame is reinforced by the mother die, so that the lead frame can be prevented from being deformed. Moreover, when the lead frame is peeled from the mother die, the encapsulating resin layer that reinforces the lead frame is also peeled from the mother die while being attached to the lead frame. In the subsequent process, the lead frame can be prevented from being deformed as much as possible. Further, since the encapsulating resin layer is formed only on the semiconductor mounting surface side of the lead frame, it is possible to reduce the thickness of the finally obtained semiconductor device.

[0007]

The present invention will be described in more detail with reference to the drawings.
FIG. 1 is a process chart showing an embodiment of the present invention. First, a lead frame 12 is formed on a mother die 10 made of a conductive material such as stainless steel by an electroforming method [FIG. )]. The obtained lead frame 12 has a stage 16 on which a semiconductor chip is mounted.
Inner lead 20 and outer lead 1 to surround
A plurality of leads 14 composed of 8 and 8 are formed. still,
As the electroforming method used in this embodiment, a known method known in Japanese Examined Patent Publication No. 48-39867 can be adopted, and a detailed description of the electroforming method will be omitted here.

Next, on the bonding areas of the stage 16 and the inner leads 20 of the formed lead frame 12, partial plating layers 22, 22 of silver or the like are formed as a pretreatment for mounting a semiconductor chip and a pretreatment for bonding. At the same time, a resist is filled between the leads of the outer lead 18 as a filler 24 for preventing resin leakage [FIG.
(B)]. Further, the semiconductor chip 26 mounted on the stage 16 of the lead frame 12 and the bonding area of the inner lead 12 are wire bonded [FIG.
(C)]. As described above, even if the lead frame 12 is partially plated or the semiconductor chip 26 is mounted, the lead frame 12 is reinforced by the mother die 10 and therefore is not deformed.

The lead frame 12 on which the semiconductor chip 26 is mounted and wire-bonded is sent to a resin encapsulation process, and the resin encapsulation portion including the semiconductor chip 26 forms an upper die and a lower die which form a resin encapsulation mold. It is inserted into the cavity 34 formed by the contact with [Fig. 1 (d)]. The cavity 34 is formed by contact between the mother die 10 used as the lower mold of the resin sealing mold and the cavity block 30 used as the upper mold of the resin sealing mold and having the cavity recess 32 formed therein. Then, a part of the lower end surface of the cavity block 30 contacts the outer lead 18 of the lead frame 12. In the cavity 34 of this resin sealing mold, a sealing resin is injected from the gate 36 to seal the resin sealing portion including the semiconductor chip 26 with a resin, and
The sealing resin layer 38 is formed. In this example,
Since the resist as the resin leakage preventing filler 24 is filled between the leads of the outer lead 18, the lower end surface of the cavity block 30 contacting the outer lead 18 and the upper surface of the mother die 10 are closed, The leakage of the sealing resin injected into the cavity 34 can be prevented.

After that, the resin sealing mold is opened and the lead frame 12 is peeled off from the mother mold 10. At the time of this peeling, since the inner resin 20 and the stage 16 of the lead frame 12 that are most easily deformed are reinforced by the formed sealing resin layer 38, the deformation caused by the peeling can be prevented. Since the inner lead 20 and the stage 16 of the lead frame 12 separated from the mother die 10 are exposed on the back surface side of the sealing resin layer 38, in order to cover and insulate the exposed surface of the inner lead 20 and the stage 16, An insulating resist is applied over the entire back surface of the sealing resin layer 38 to form an insulating layer 40. [FIG. 1 (e)]. The obtained semiconductor device is further subjected to plating or the like, if necessary. Even at this time, the inner lead 20 and the like can be prevented from being deformed by the reinforcement by the sealing resin layer 38. As described above, in this embodiment, after the stage 16 and the inner leads 20 are reinforced by the sealing resin layer 38, the mother die 10 is
The support bar supporting the stage 16 can be eliminated, and the resin leakage preventing filler 24 can be eliminated.
The resist is filled between the leads of the outer leads 18 to prevent resin leakage of the sealing resin, so that the dam bar can be eliminated.

In the semiconductor device obtained by the process shown in FIG. 1, the height of the bonding surface between the mounted semiconductor chip 26 and the inner lead 20 is different. In this respect, as shown in FIG. 2, by making the portion of the mother die 10 on which the stage 16 is formed a recess, the bonding surface of the mounted semiconductor chip 26 and the bonding surface of the inner lead 20 can be made to be at the same height. it can. Further, as the pattern of the inner leads becomes finer, the outer leads 18 protruding from the sealing resin layer 38 also become thinner and thinner,
Its strength decreases and it becomes easy to deform. Therefore, as shown in FIG. 3, it is not necessary to form the outer leads 18 by projecting the bumps 42, 42, ... On the inner leads 20 reinforced by the sealing resin layer 38. The bump 42 is made of solder metal and has a tip protruding from the insulating layer 40.

.. are formed on the circuit board 44 bonded to the exposed surface of the inner lead 20 of the lead frame 12 separated from the mother die 10 as shown in FIG. It is possible to improve the degree of freedom in the formation position of the wiring, and it is possible to improve the electrical characteristics by providing a ground, a planar line, or the like in the circuit board 44. As such a circuit board 44, a flexible printed wiring board having a circuit pattern formed on a resin film such as polyimide or a printed circuit board (PCB) having a circuit pattern formed on a resin board can be used, and the inner leads 20 are exposed. It is possible to use one having a through hole formed on the joint surface with the surface. Such a circuit board 44
First, the circuit board 44 is connected to the inner lead 20.
After the insulating adhesive is applied to the opening of the through hole and / or the surface of the sealing resin layer 38 excluding the exposed surface of the inner lead 20 by screen printing or the like, the exposed surface of the inner lead 20 and the circuit board 44. The both are joined so that the openings of the through holes are joined. Then, the conductive paste is filled in the through holes, or a metal such as copper is piled up by plating to electrically connect the two. A ceramic circuit board can also be used as the circuit board 44. It is usual that the ceramic circuit board is preliminarily formed with a bonding terminal to the exposed surface of the inner lead 20. Therefore, a conductive adhesive is applied to the joint terminals of the ceramic circuit board and / or the exposed surface of the inner leads 20 of the sealing resin layer 38 by screen printing or the like, and the joint terminals and / or the inner leads 20 are exposed. Apply insulating adhesive to all surfaces except surfaces. After that, the exposed surface of the inner lead 20 and the joining terminal of the circuit board 44 are joined together so that the ceramic circuit board and the inner lead 20 can be electrically connected.

On the other hand, when it is necessary to form the outer leads 20, the outer leads 20 can be thickened and reinforced by performing electroforming twice on the outer leads 20. That is, after the stage 16, the outer lead 18, and the inner lead 20 having the same thickness are formed by the first electroforming, the stage 16 and the inner lead 20 are covered with a mask to expose only the outer lead 18. Perform the second electroforming. The outer lead 18 of the semiconductor device thus obtained can have higher strength than the inner lead 20. In the present embodiment, the case where one semiconductor chip 26 is mounted on the lead frame 12 has been described, but a plurality of semiconductor chips may be mounted.

[0014]

According to the present invention, since it is possible to prevent deformation of a lead frame having a fine pattern formed by an electroforming method, a semiconductor device mounted with a highly integrated semiconductor chip and a miniaturized and thinned semiconductor device. The device can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a process chart for explaining an example of the present invention.

FIG. 2 is a partial cross-sectional view for explaining another embodiment.

FIG. 3 is a partial cross-sectional view for explaining another embodiment.

FIG. 4 is a vertical sectional view for explaining another embodiment.

FIG. 5 is an explanatory diagram for explaining an electroforming method.

[Explanation of symbols]

 10 Mother Mold 12 Lead Frame 16 Stage 18 Outer Lead 20 Inner Lead 22 Partial Plating Layer 24 Resin Leak Preventing Filler 26 Semiconductor Chip 30 Cavity Block 32 Cavity Recess 34 Cavity 38 Sealing Resin Layer 40 Insulating Layer 42 Bump 44 Circuit Board

Claims (5)

[Claims] 1. When a semiconductor chip is mounted on a lead frame formed by an electroforming method and a resin-sealed portion including the semiconductor chip is resin-sealed to manufacture a semiconductor device, the resin-sealing is performed. The lead frame formed on the mother die without being separated from the mother die after the lead frame is formed on the mother die used for one of the molds forming the resin-sealed mold by the electroforming method. Then, the semiconductor chip is mounted on, and then the other mold constituting the resin-sealing die is brought into contact with the mother die on which the lead frame is formed, and the resin seal formed by the other die and the mother die. Insert the resin-sealing portion containing the semiconductor chip into the cavity of the die, and then inject the sealing resin into the cavity by the sealing resin layer formed. The strength has been the lead frame,
A method of manufacturing a semiconductor device, which comprises peeling from the mother die. 2. The method for manufacturing a semiconductor device according to claim 1, wherein an insulating layer is formed on an exposed surface of the inner lead of the lead frame separated from the mother die. 3. The method for manufacturing a semiconductor device according to claim 1, wherein a resin leak preventing filler is filled between the leads of the outer leads formed on the mother die that abuts the other die. 4. The semiconductor according to claim 1, wherein an insulating layer is formed on an exposed surface of the inner lead of the lead frame separated from the mother die, and a bump protruding from the insulating layer is provided on the exposed surface of the inner lead. Device manufacturing method. 5. The circuit board is bonded to the exposed surface of the inner lead of the lead frame separated from the mother die.
A method for manufacturing a semiconductor device as described above.