JPH05326587A - Method and device for sealing resin-sealed-type semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the deformation of a die pad or the occurrence of voids by letting fused rein flow into a mold, while fixing a die pad inside a mold so that the die-pad may not shift by the fused resin by the fused resin flowing in the mold, thereby sealing a semiconductor chip with resin. CONSTITUTION:When a lead frame, where a semiconductor chip 8 is mounted and fixed on a die pad 2, is placed in the specified position of a bottom force 30A and is fastened with top and bottom forces 20A and 30A, being welded with the top force 20A, opposed die pad fixing pins 25 and 32 press the flat part of each suspension lead 6. When sealing resin is injected from an injection port 31 in this condition, even if a difference occurs in the passages above and below the semiconductor chip 8, wherein resin is flowing, the voids or the deformation of the die pads or the suspension lead 6 can be avoided at sealing with resin since each suspension lead 6 suspending the die pad 2 is fixed. Moreover, the die pad 2 never twists.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin encapsulation type semiconductor device, and more particularly to a resin encapsulation method suitable for use in a resin-encapsulation type semiconductor device which is extremely thin and an apparatus therefor.

[0002]

2. Description of the Related Art A molding die which is a main component of a conventional resin encapsulation apparatus and a resin encapsulation method using this molding die will be described with reference to FIGS. FIG. 3 is a plan view showing a current lead frame used in a general QFP type semiconductor device for explaining the present invention, and FIG. 4 is a prior art in which a semiconductor die is resin-sealed with a molding die. 2A is a plan view showing a molding surface of a lower mold part, FIG. B is a semiconductor chip mounted on and inside the line BB in FIG. And FIG. 5 is a partial cross-sectional view of the upper and lower molding dies with the lead frame accommodated therein, and FIG. 5 is a cross-sectional view for explaining the phenomenon that occurs when resin sealing is performed by the transfer molding method of the prior art, FIG. 6 is a partial cross-sectional view of a conventional molding die in which a resin injection port is provided in both upper and lower molds and a lead frame having a semiconductor chip mounted therein is housed.
7 is a view for explaining another conventional resin sealing method, and FIG. 7A is a plan view partially showing the molding surface of the lower die.
FIG. B is a partial cross-sectional view of the upper and lower molding dies on the line BB of FIG. A and in a state in which a lead frame having a semiconductor chip mounted therein is housed.

First, FIG. 3 shows an active lead frame 1 used in a general QFP type semiconductor device in only one unit. The lead frame 1 is a quadrilateral die pad 2, a plurality of inner leads 3 arranged at a predetermined pitch along each side of the die pad 2, and the inner leads 3 arranged correspondingly to the tie bars 4. The outer leads 5 are connected to each other, and the suspension leads 6 that connect the corners of the die pad 2 to the stays 7 are formed. Since each suspension lead 6 is bent downward at the bent portion 6a, the die pad 2 is in a depressed state.

The lead frame 1 configured as described above
The semiconductor chip 8 is adhered and fixed to the die pad 2 using silver paste or the like, and the semiconductor chip 8 (FIG. 4)
After each electrode and the inner end of each inner lead 3 are wire-bonded, such a semiconductor chip 8 is resin-sealed by a transfer molding method.

As shown in FIG. 4B, the molding die for resin sealing is composed of an upper die 20 and a lower die 30. In addition, the molding surface 20a of the mold 20 has 1
Projections such as a pin 21 indicating the second lead and an ejector pin 22 for separating the molded resin sealing device from the mold are formed. Reference numeral 31 indicates a sealing resin injection port 31 provided in the lower mold 30.

The lead frame 1 having the semiconductor chip 8 mounted thereon is placed at a predetermined position on the lower die 30 of the sealing die having such a structure, and the molten sealing resin is injected from the injection port 31. The semiconductor chip 8 and the like can be resin-sealed.

[0007]

Recently, there has been an increasing demand for thinner resin-encapsulated semiconductor devices. Problems encountered when resin-sealing a semiconductor chip in order to obtain such a thin resin-encapsulated semiconductor device are as follows.

That is, considering the sealing resin that flows above and below the semiconductor chip, even if the depth Ta and the depth Tb are designed to be the same in FIG. 4B, the upper die 20 and the lower die 3 are designed.
The injection port 31 of the lower mold 30 is affected by variations in the space from 0, the thickness of the semiconductor chip 8, the thickness of the adhesive that fixes the semiconductor chip 8 and the die pad 2, the depressing amount of the lead frame 1, and the like. There is a difference between the upper and lower passages of the semiconductor chip 8 through which the sealing resin supplied from the semiconductor chip 8 flows. For example, when the depth Ta of the lower passage becomes deeper than the depth Tb of the upper passage, the semiconductor chip 8 is slightly different. Of the encapsulating resin flowing above the semiconductor chip 8 is hindered, and the speed of the encapsulating resin flowing above the semiconductor chip 8 is slower than that of the encapsulating resin flowing above the semiconductor chip 8. As a result, the die pad 2 is moved up and down, and the lower sealing resin wraps around upward, confining the gas in the molding die and generating voids.

When this phenomenon further progresses due to the presence of the protrusions present on the molding surface 20a of the upper die 20, as shown in FIG. 5B, the sealing resin flowing below the semiconductor chip 8 is removed. It pushes up the die pad 2 and deforms it.

Further, as shown in FIG. 6, even if the upper die 20 is provided with an injection port 23 and the injection port is made symmetrical, if there are variations in the above-mentioned various thicknesses, the semiconductor chip 8 is vertically moved. There is a difference in speed between the sealing resins flowing through, and the same problems as described above occur.

In order to prevent such a problem, as shown in FIG. 7, a fixing pin 24 and a fixing pin 32 which come into contact with the upper part of the semiconductor chip 8 and the lower part of the die pad 2, respectively, are provided in the upper mold 20 and the lower mold, respectively. Although the semiconductor chip 8 and the die pad 2 can be held by the fixing pins 24 and 32, the surface of the semiconductor chip 8 is easily damaged by the fixing pins 24, which may adversely affect the reliability. is there. An object of the present invention is to eliminate such inconvenience.

[0012]

Therefore, according to the present invention, when the resin is sealed by the transfer molding method, the die pad is moved in the molding die so that the die pad does not move due to the molten resin flowing into the molding die. While being fixed, a molten resin is poured into a molding die to seal the semiconductor chip with a resin.

Further, it is desirable that the die pad is fixed on a diagonal line of the die pad.
The die was fixed so that the die pad was fixed by pressing the suspension lead.

[0014]

Therefore, even if the speed difference occurs in the sealing resin flowing in the upper and lower passages of the semiconductor chip, the die pad may change,
There is no deformation.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A resin encapsulation method for a QFP type resin encapsulation type semiconductor device of the present invention and an apparatus thereof will be described below with reference to FIGS. FIG. 1 is a first embodiment of a resin sealing device of the present invention, and FIG. 1A is a schematic plan view showing a main part thereof.
FIG. 3B is a sectional view taken along the line BB of FIG. In FIG. 1, the same components as those of the conventional resin sealing device are designated by the same reference numerals.

In the resin sealing device of the present invention shown in FIG. 1, the flat portion 6 immediately above the bent portion 6a of each suspension lead 6 which is one component of the lead frame 1 shown in FIG.
As shown in FIG. 1B, the molding surface 2a is formed on the molding surface 20a of the upper mold 20A so that it can be sandwiched from above and below.
0a vertically inwardly project four die pad fixing pins 25, and one molding die surface 30a of the lower die 30A faces each of the die pad fixing pins 25 from the molding surface 30a. Four die pad fixing pins 32 vertically projecting inward were set up. Those die pad fixing pins 2
At least one of 5 and 32 is configured to be planted at a position close to the resin injection port 31.

The resin injection port 31 is formed at one corner of the molding portion of the lower mold 30A, and the molten resin is injected from this injection port 31, like the conventional molding die.

The die pad fixing pins 25 and 32 need not be provided for each suspension lead 6, but are preferably provided at least at a position near the resin injection port 31 and a corner farthest from the injection port 31 on the diagonal line.

The semiconductor chip 8 is mounted on the die pad 2 and the fixed lead frame 1 is placed at a predetermined position on the lower die 30A of the molding die which is the resin sealing device having the above-mentioned structure, and the upper die is placed. Crimp this lead frame 1 with 20A,
When tightened by the upper and lower molds, the opposing die pad fixing pins 25 and 32 press the flat portion 6b of each suspension lead 6 as shown in FIG. 1B.

In this state, when the sealing resin is injected from the injection port 31 toward the diagonal line of the die pad 2, the difference in space between the upper mold 20A and the lower mold 30A, the semiconductor chip 8
Of the adhesive for fixing the semiconductor chip 8 and the die pad 2, the amount of depressing of the lead frame 1 and the like, the sealing resin supplied from the injection port 31 of the lower mold 30A flows through the semiconductor. Even if there is a difference in the upper and lower flow paths of the chip 8, since the suspension leads 6 that suspend the die pad 2 are fixed, voids or die pads during resin sealing,
The deformation of the suspension lead 6 can be avoided.

Die pad fixing pin 2 in this embodiment
Since 5 and 32 press the flat portion 6b of the suspension lead 6 close to the die pad 2, and further press the die pad 2 on the diagonal of the die pad 2, the die pad 2 is not twisted.

Further, in the second embodiment of the resin sealing device of the present invention shown in FIG. 2, each corner of the die pad 2 of the lead frame 1 shown in FIG. 3 is, as shown in FIG. 2B, Upper mold 20 so that it can be sandwiched from above and below
On the molding surface 20a of B, four die pad fixing pins 25 projecting vertically inward from the molding surface 20a are planted, and on the molding surface 30a of one lower die 30B, the die pad fixing pins 25 are also formed. , Four die pad fixing pins 32 vertically projecting inward from the molding surface 30a were planted.

In this structure, since the die pad fixing pins 25 and 32 directly press the die pad 2, the effect of preventing the movement and deformation of the die pad 2 is greater than that of the first embodiment shown in FIG. Depending on the dimension, the die pad 2 has a reduced area that can be pressed by these pins, and in some cases there is no place to press, so there is the disadvantage that pressing cannot be done.

Therefore, the bent portion 6a of each suspension lead 6
It is most desirable to form the flat portions 6c (FIG. 3) of the suspension leads 6 as much as possible between the corners of the die pad 2 and the die pads 2, and to form the die pad fixing pins 25 and 32 that can press these flat portions 6c.

Although the QFP type semiconductor device has been described in the above embodiment, the present invention is not limited to the semiconductor device in which the outer leads are led out in four directions, and the outer leads are unidirectionally or bidirectionally provided. It will be easily understood that the present invention can also be applied to the resin-sealed semiconductor device from which

[0026]

As is apparent from the above description, according to the resin molding apparatus of the present invention, the die pad fixing pins are provided on the upper and lower molds respectively, and the resin of the semiconductor chip is fixed while fixing the die pad with these die pad fixing pins. Since the sealing is performed, even if there is a difference in the flow rate of the sealing resin in the molding die due to the difference in the depth of the resin passages above and below the semiconductor chip due to variations in the components, etc. It does not move or is deformed, the quality of the resin-encapsulated semiconductor device can be favorably maintained, and the yield can be improved.

[Brief description of drawings]

FIG. 1 is a first embodiment of a resin sealing device of the present invention, FIG. 1A is a schematic plan view showing the main part thereof, and FIG. 1B is on the line BB of FIG. FIG. 3 is a partial cross-sectional view of a state in which a lead frame having a semiconductor chip mounted therein is housed therein.

FIG. 2 is a second embodiment of the resin sealing device of the present invention, FIG. 2A is a schematic plan view showing the main part thereof, and FIG. 2B is on the line BB of FIG. FIG. 3 is a partial cross-sectional view of a state in which a lead frame having a semiconductor chip mounted therein is housed therein.

FIG. 3 is a plan view showing a current lead frame used in a general QFP type semiconductor device for explaining the present invention.

4A and 4B are views for explaining a conventional resin sealing method of resin-sealing a semiconductor chip with a molding die. FIG. 4A is a plan view showing a molding surface of a lower die, and FIG. BB of the same figure A
FIG. 3 is a partial cross-sectional view of the resin sealing device on a line and in a state where a lead frame having a semiconductor chip mounted therein is housed therein.

FIG. 5 is a cross-sectional view for explaining a phenomenon that occurs when resin sealing is performed by a transfer molding method of a conventional technique.

FIG. 6 is a partial cross-sectional view of a conventional resin sealing device in which a resin injection port is provided in both upper and lower molds and a lead frame in which a semiconductor chip is mounted is housed.

7A and 7B are views for explaining another resin sealing method of the prior art, where FIG. 7A is a plan view showing a molding surface of a lower mold part, and FIG. 7B is a view on line BB in FIG. FIG. 3 is a partial cross-sectional view of the resin encapsulating device in a state in which a lead frame having a semiconductor chip mounted therein is housed therein.

[Explanation of symbols]

 1 lead frame 2 die pad 3 inner lead 6 suspension lead 6a bent portion 6b flat portion 6c flat portion 8 semiconductor chip 20 upper die 20a molding surface 20A upper die 20B upper die 23 resin injection port 25 die pad fixing pin 30 lower die 30a Molding surface 30A Lower mold 30B Lower mold 31 Resin injection port 32 Die pad fixing pin

Claims (3)

[Claims] 1. A semiconductor chip is fixed to the die pad of a lead frame composed of a die pad, an inner lead, an outer lead, etc., and each electrode of the semiconductor chip is electrically connected to an inner end portion of the inner lead. After that, when such a semiconductor chip is molded by a transfer molding method using a molding die, the die pad is not moved by the molten resin flowing into the molding die so that the die pad does not move in the molding die. A method for resin encapsulation of a resin-encapsulated semiconductor device, which comprises pouring a molten resin into the molding die while encapsulating the semiconductor chip to encapsulate the semiconductor chip with a resin. 2. The die pad is a quadrilateral, and when fixing such a die pad in the molding die, each corner of the quadrilateral is pressed down.
7. A method for resin-sealing a resin-sealed semiconductor device according to item 4. 3. A semiconductor chip is fixed to the die pad of a lead frame composed of a die pad, an inner lead, an outer lead, etc., and each electrode of the semiconductor chip is electrically connected to an inner end portion of the inner lead. After that, the die pad is formed on the molding surfaces of the upper and lower molds of the resin molding device of the resin molding type semiconductor device including the upper mold and the lower mold for resin-molding such a semiconductor chip by the transfer molding method. A resin encapsulation device for a resin encapsulation type semiconductor device, wherein means for fixing the die pad is formed so as not to be moved by the molten resin flowing into the two dies.