JP2584028B2 - Semiconductor chip mold press machine - Google Patents

Description

The present invention relates to a semiconductor chip mold press apparatus,
In particular, it relates to means for absorbing the volume error of the tablet and equalizing the feed pressure for pressing the molten tablet into the cavity.

(Prior art) A mold press means for molding a semiconductor chip mounted on a lead frame with a resin, positions the chip in a cavity formed in a mold composed of an upper mold and a lower mold, and then forms the chip in the lower mold. After the attached tablet made of synthetic resin is pushed up by a plunger, the heated and melted tablet is pressed into the cavity at a predetermined feed pressure from the gate, and after holding pressure and curing (curing),
The upper mold and the lower mold are separated from each other, and the lead frame in which the mold for protecting the semiconductor chip is formed is removed from the mold. However, since the tablet has a volume error, the feed pressure when the tablet is pushed up with a plunger and pressed into the cavity is varied, which causes problems such as defects in the molded body and deformation of the lead frame. there were.

FIG. 6 shows a conventional feed pressure adjusting means for solving such a problem, wherein 100 and 101 are a lower mold and an upper mold of a mold, and 102 is a tablet mounted on a mounting portion 103 of the lower mold 100. , 104 are driven by lifting means (not shown) to
02 is a plunger that pushes up the tablet 102 from above with a pressure adjusting pin 106 urged downward by a pressure adjusting spring 105. Therefore, when the plunger 104 is raised to push up the tablet 102 and press the molten tablet 102 into the cavity 107 to form the mold body 108,
A portion 102a of the molten tablet 102 pushes the pin 106 up against the spring force of the spring 105 and is pressed into the upper die 101, thereby absorbing a volume error of the tablet 102.

(Problems to be Solved by the Invention) However, the above-mentioned means still causes a slight variation in the feed pressure of the tablet 102 because the variation in the spring characteristics of the spring 105, particularly the variation in the spring force due to the amount of the part 102a occurs. There was a problem that occurred.

Therefore, an object of the present invention is to provide means capable of absorbing a volume error of a tablet and equalizing a feed pressure for press-fitting a molten tablet into a cavity.

(Means for Solving the Problems) For this purpose, the present invention provides a base unit which is driven by an elevating device and which moves up and down, and supports each plunger which pushes up a plurality of tablets arranged and mounted in a lower mold on the base unit. And a common oil reservoir is provided for these hydraulic cylinders. The lifting device includes a motor, a nut, and a feed screw screwed to the nut, and drives the motor to raise and lower the base.

(Operation) According to the above configuration, since the hydraulic cylinder is interposed between the lifting / lowering device and the plunger and the oil reservoir of each hydraulic cylinder is common, even if the tablet has a volume error, this volume error Is absorbed by the hydraulic cylinder, and each tablet is pressed into the cavity with an equal feed pressure.

Example Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is an overall perspective view of a mold press apparatus.
Reference numerals 1, 2, and 3 denote a fixed base, a lifting platen, and a fixed top plate that are stacked via the lifting guide tie bar 4.
A lower mold 5 of the mold is mounted on the upper surface of the base 1, and an upper mold 6 is mounted on the lower surface of the platen 2. LF is a lead frame set on the lower die 5 and a plurality of semiconductor chips mounted on the lower die 5 at a pitch are molded by this mold press. Reference numeral 7 denotes a press motor composed of an AC servomotor disposed on the top plate 3, and its rotation is transmitted to a worm wheel 9 via a deceleration worm 8. Reference numeral 10 denotes a feed nut mounted on the axis of the worm wheel 9, and reference numeral 11 denotes a vertical ball screw driven by the nut 10. The platen 2 is attached to the lower end of the ball screw 11. When the motor 7 is driven, the platen 2 moves up and down, and the upper die 6 comes into contact with and separates from the lower die 5. Reference numeral 12 denotes a cover casing, and reference numeral 13 denotes an AC servomotor for driving a plunger (described later) of the tablet 17 provided below the base 1.

FIG. 2 is a cross-sectional view of the lower mold 5 and the upper mold 6. Numeral 17 denotes a columnar tablet, and a plurality of tablets are arranged on a mounting portion 18 formed of a cylindrical casing disposed on the upper part of the lower mold 5. It is mounted (see also FIGS. 4 and 5). This tablet 17 is made of a thermosetting resin, for example, 130 to 180 ° C.
When a certain amount of heat is applied, the material has a property of being once melted and then quickly cured. The heating means of the tablet 17 is
It is omitted because the figure becomes complicated.

Reference numeral 19 denotes a rectangular cavity recessed in the upper surface of the lower mold 5. The cavity 19 communicates with the mounting portion 18 via a groove-shaped gate 20. Chip P mounted on LF (see Fig. 5)
By pressing the heated and melted tablet 17 in a state where is positioned, a molded body 17a for molding the chip P is formed (see FIG. 3). Reference numeral 21 denotes an ejector pin which protrudes and sinks from the bottom surface of the cavity 19. When the molding operation is completed, the ejector pin 21 pushes up the molded body 17a and removes the lead frame LF from the lower die 5. The cavity 19 is also recessed on the lower surface of the upper die 6 facing the cavity 19 (see FIG. 3).
Reference numeral 22 denotes a grooved air vent for releasing gas in the molten tablet.

In FIG. 2, a tablet is provided below the mounting portion 18.
The plunger 25 which pushes up 17 upwards is inserted.
Reference numeral 26 denotes a push-up rod for the plunger 25, which stands on a horizontal base member 27. Numeral 28 denotes an elevating / lowering device for the base member 27.
A nut 30 driven by the motor 13 through 29, a vertical feed screw 31 screwed to the nut 30, and a push-up plate 32 attached to the upper end of the feed screw 31, When the device 13 is driven, the base member 27 is raised, and the plunger 25 erected on the base material 27 is also raised to push up the tablet 17.

2 and 3, reference numeral 33 denotes the ejector pin.
21 is a push-up member, 35 is a protrusion standing upright on the base member 27, and when the motor 13 is driven to raise the base member 27, the push-up member 33 is pushed up by the protrusion 35 and rises, and the ejector pin 21 is moved up by the cavity 19. The mold 17a inside is pushed up, and the mold 17a is removed from the lower die 5. Numeral 40 denotes a hydraulic cylinder disposed on the base member 27, which comprises a piston 40a and a casing 40b.
Are supported, respectively. 41 is the base material 27
This is a horizontal hole-shaped oil reservoir formed in the inside of the cylinder, and applies hydraulic pressure to the piston 40a. Oil reservoir 4
Both ends are closed by a stopper 42 to form a sealed structure. The oil reservoir 41 is a common oil reservoir for each hydraulic cylinder 40, and each piston of each hydraulic cylinder 40
Apply a hydraulic pressure equal to 40a.

The present apparatus has the above configuration, and the operation will be described next.

After the press motor 7 is driven to raise the upper die 6, the tablet 17 is set in the mounting portion 18, and then the upper die 6 is lowered to make close contact with the lower die 5. Next, the motor 13 is driven to raise the base material 27, and the heated and melted tablet 17 (hereinafter, referred to as the tablet 17)
“Molten resin” is pressed into the cavity 19. In this case, although the tablets 17 have a volume error, each tablet 17 is pushed up through the hydraulic cylinder 40, so that each tablet 17 is pressed into the cavity 19 with the same feed pressure. In FIG. 2, t is a variation in the upper surface position of the plunger 25 based on the volume error.

If the cavity 19 is filled with molten resin, the motor
The feed pressure is reduced by lowering the torque of 13, and the holding pressure and curing are continuously performed to cure the resin in the cavity 19. When the curing is completed, the motor 7 is driven again to raise the upper die 6, and the motor 13 is driven to push up the ejector pins 21 of the molded body 17 a molded in the cavity 19. Remove from lower mold 5.

(Effects of the Invention) As described above, the present invention provides a base unit which is driven by an elevating device to move up and down, and which supports each plunger which pushes up a plurality of tablets mounted in a lower mold on the base unit. In addition to providing cylinders and oil reservoirs common to these hydraulic cylinders, the hydraulic cylinders absorb tablet volume errors and press-fit each tablet into the cavity with equal feed pressure. The body can be shaped. Further, the lifting device comprises a motor, a nut, and a feed screw screwed to the nut, and the motor is driven to raise and lower the base portion. Control the feed pressure precisely by controlling the torque of the motor,
Hold pressure and cure can be performed accurately.

[Brief description of the drawings]

1 shows an embodiment of the present invention. FIG. 1 is a perspective view of a mold press apparatus, FIG. 2 is a sectional view of a mold, and FIG.
FIG. 4 is a partial perspective view of the lower die, FIG. 5 is a plan view of the lower die, and FIG. 6 is a cross-sectional view of the conventional device. LF Lead frame P Semiconductor chip 5 Lower die 6 Upper die 17 Tablet 19 Cavity 25 Plunger 27 Base 28 Lifting device 40 Hydraulic cylinder 41 Oil reservoir

Claims (1)

(57) [Claims] 1. A mold comprising an upper mold and a lower mold having a plurality of cavities for molding a semiconductor chip on which a lead frame is mounted, the plurality of cavities being arranged side by side on surfaces facing each other. In a mold press device in which the tablets mounted side by side are pushed up by a plunger driven by an elevating device to press each of the heated and melted tablets into each of the cavities, a base portion which is driven by the elevating device to ascend and descend A hydraulic cylinder for supporting each of the plungers is provided on the base portion, a common oil reservoir is provided for the hydraulic cylinders, and the elevating device is screwed on the motor, the nut, and the nut. A semiconductor device, comprising: a feed screw having a base portion; and the base portion being moved up and down by driving the motor. Tsu mold press apparatus-flops.