JP3166406B2 - Mold for transfer molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer molding die used for sealing a semiconductor element provided on a lead frame with a resin.

[0002]

2. Description of the Related Art Conventionally, as a transfer molding die of this type, a plurality of cavities, one pot for heating and melting a resin tablet supplied from the outside, and a resin melted in the pot are supplied to each cavity. And a driving mechanism for driving the plunger, a one-pot type plunger has been used. In this one-pot transfer mold, when the number of cavities is increased to improve productivity, the amount of resin charged in the pot increases, and it takes time to melt the resin, The length of the melting passage from to the respective cavities also becomes extremely non-uniform, causing variations in the pressure and temperature of the resin before filling each cavity,
There is a problem that the amount of resin filled in each cavity is different, and the quality of the molded product in each cavity varies. So, to solve this problem,
A multi-pot transfer molding die has been developed in which a plurality of pots are provided to reduce the amount of resin melted in each pot and to make the length of each resin passage as uniform as possible.

[0003]

In the above multi-pot transfer mold, a large number of plungers are connected to a pressing plate of one driving mechanism, and the pressing plate is connected to a plurality of guide pins. , The resin in each pot is simultaneously extruded by each plunger. Therefore, when the pressing plate supported by each of the guide pins is inclined due to thermal deformation or the like, the movement of each plunger is not performed smoothly and uniformly, and imbalance occurs in the resin injection pressure into each cavity. In addition, there is a problem that the amount of resin filled in each cavity varies.

The present invention has been made in view of the above circumstances, and has as its object to smoothly and reliably move a pressing plate for driving a plunger even when thermal deformation or the like occurs. An object of the present invention is to provide a transfer molding die which can make the injection pressure of resin into each cavity uniform.

[0005]

In order to achieve the above-mentioned object, the present invention provides a method comprising: forming a plurality of cavities between a pair of molds; providing a plurality of pots respectively communicating with the cavities; A plurality of plungers for extruding the tablets loaded in the pots into the respective cavities are provided, and in a transfer molding die that simultaneously presses and drives these plungers, a pressing plate is provided with a plurality of guides for each of the plungers. The guide pin is supported by a pin and is provided so as to be able to approach and separate from the mold, and these guide pins are provided with a resilient member for urging the press plate in a direction to separate the press plate from the mold plate, and the press plate The drive shaft is detachably connected to the drive shaft, and a contact surface of the drive shaft with the pressing plate is formed in a rectangular shape.

[0006]

According to the transfer mold of the present invention,
By the rectangular contact surface of the drive shaft that moves the pressing plate,
In addition to suppressing rattling between the drive shaft and the pressing plate, the pressure of the resin injected into the cavity is reduced by moving the pressing plate while adjusting the position of the pressing plate by a resilient member provided on each guide pin. Make it uniform.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

In these figures, reference numeral 10 denotes an upper die, and the upper die 10 is provided so as to be vertically movable relative to a lower die 20. In the upper mold 10 and the lower mold 20, the mold plates 102, 202 are provided on the base plates 100, 200 via the spacers 101, 201, respectively, and the mold supports 103,
203, and these mold supports 103, 20
3. Center dies 104 and 204 and product dies 105 and 205
Are fitted, and these molds 104, 105,
Protruding mechanisms 106 and 206 for releasing the solidified resin and the molded product in the resin passage from the molds 204 and 205 are provided, while the base plate 200, the protruding mechanism 206, and the mold plate 2 are provided.
02, the mold support 203 and the center mold 204 are provided with a large number (2 rows × 8 = 16) of pots 207.

The protruding mechanism 106 is provided on the base plate 10.
0, and a protruding plate 106a and a holding plate 106b movably provided in the mold opening / closing direction between the pressing plate 106b and the pressing plate 106b. Template 102, mold support 1
03 and the protruding pins 106c, 106d, and 106e penetrating the center mold 104 or the product mold 105, and are mounted between the base plate 100 and the protruding plate 106a.
A projecting spring 106f for biasing the projecting plate 106a, a biasing device 106g movably provided on the projecting plate 106a and abutting against a base end surface of the projecting pin 106c, The shock-absorbing spring 10 provided between the plate 106a and the urging tool 106g to urge the urging tool 106g toward the protruding pin 106c
6h. The protruding pin 106c is provided to face the pot 207, and is formed in the resin mold portion 104a formed in the center mold 104.
This is for releasing the solidified resin in the mold. In the drawing, reference numeral 106i denotes the protruding plate 106a, the holding plate 1
06b and a return pin for returning the protruding pins 106c to 106e to their original positions.

The protruding mechanism 206 is connected to the base plate 20.
0 and the mold plate 202, and a protruding plate 206a and a holding plate 206b movably provided in the mold opening and closing direction, and a base end portion sandwiched between the pushing plate 206a and the holding plate 206b. Template 202, mold support 2
03 and the protruding pin 206 penetrating the product mold 205
c, 206d, provided on the protruding plate 206a,
And a projecting rod 206e for urging the projecting plate 106a, the mold plate 202 and the projecting plate 206a.
And a return spring 206f for returning the projecting plate 206a to its original position. The protruding plate 206a and the holding plate 206b
The protruding pins 206c and 206d are pushed out toward the upper die 10 by a protruding member 206g via a protruding rod 206e, and a return spring 206 is provided.
f and a return pin (not shown) sandwiched between the protruding plate 206a and the holding plate 206b, so that the upper die 10 returns to the original position.

Each of the pots 207 includes an upper pot body 207.
The lower end of a is screwed into the upper end of the lower pot body 207b, and a flange 207c is formed above the screw portion of the upper pot body 207a. A flange 207d is formed at the lower end of the lower pot body 207b. The flange portion 207d is mounted in the base plate 200, and is attached to the base plate 200 by mounting bolts 207e inserted from below the base plate 200.
It is fixed to.

A plunger 300 of the plunger unit 30 is inserted into each of the pots 207 from below. The plunger unit 30 is mounted on the base plate 2.
00, and the mounting plate 30
1 supporting plate 30 attached via spacer 302
3, four guide pins 304 provided between the mounting plate 301 and the support plate 303, and a pressing plate 306 provided on the guide pins 304 via a guide mechanism 305 so as to be movable in the mold opening / closing direction. And a tilt adjusting spring 307 provided between the pressing plate 306 and the mounting plate 301 and biasing the pressing plate 306 toward the support plate 303, and is detachable from the pressing plate 306 via a mounting member 308. The drive shaft 309 connected to the pressing plate 306 and the detachable mechanism 3
And the above-mentioned plunger 300 attached through the base 10.

On the upper surface of the mounting plate 301, two discharge grooves 301a intersecting with the plungers 300 are formed in a direction orthogonal to the mold opening and closing direction. A seal member 301b is mounted around each of the plungers 300 in both the discharge grooves 301a, and a bottom plate 301c is laid on these seal members 301b. The four corners of the pressing plate 306 are supported by the guide pins 304 while maintaining a slight clearance, and the inclination of the pressing plate 306 can be adjusted by the clearance. Further, the drive shaft 30
The upper end of 9 has a neck portion 309a formed in a small diameter, and a head portion 309c connected to the neck portion 309a and having a rectangular contact surface 309b with the pressing plate 306. And, it is constituted by an attachment 308 attached to the pressing plate 306 and the pressing plate 306,
And a storage space 31 opened in a direction orthogonal to the mold opening and closing direction.
1, a head 309c of the drive shaft 309 is mounted, and the drive shaft 30 is inserted into a mounting groove 312 which is connected to the storage space 311 and is formed in the mounting fixture 308.
Nine necks 309a are mounted. Furthermore, the attachment / detachment mechanism 310 attaches the attachment 310a to the pressing plate 306.
A mounting recess 310b for mounting the base end of the plunger 300 is formed in the mounting tool 310a, and the mounting recess 310b is mounted on the mounting tool 310a.
A plurality of communication holes 310c communicating with the plunger 300 are mounted in the communication holes 310c, and a sphere 310d that can be moved toward and away from the plunger 300 in the radial direction is mounted in the communication holes 310c. The movable cylinder 310e is provided so as to be movable in the axial direction, while the movable cylinder 3
10e, the sphere 310d is inserted into the plunger 300.
A large-diameter hole portion 310f is formed to retreat outward from the cylinder. Further, the moving cylinder 310e is urged from the pressing plate 306 to the mounting plate 301 side of the moving cylinder 310e, so that the spherical body 310d is moved to the plunger. Pressing spring 3 for pressing against mounting recess 300a formed in 300
10 g is attached.

In the transfer molding die configured as described above, when the resin tablet is loaded into the pot 207, the resin tablet is extruded by each plunger 300, so that each center mold 1 is extruded.
After the molten resin is supplied into the cavities formed between the product dies 105 and 205 through the resin passages formed in the product dies 104 and 204 and the product dies 105 and 205, a molded product is formed in the cavities. In the opening process, the protrusion mechanism 1
In addition, the projecting pins 106c, 106d, and 106e release the solidified resin and the molded product in the resin passage from the center pool 104 of the upper die 10 and the resin reservoir 104a of the product mold 105, and the projecting mechanisms 206 project. The product mold 2 of the lower mold 20 is set by the pins 206c and 206d.
From 05, the solidified resin and the molded product are released from the mold and collected. Here, the operation of raising and lowering each of the plungers 300 is performed by raising and lowering the drive shaft 309 via the attachment / detachment mechanism 310, the pressing plate 306, and the attachment 308. In this case, the head 309c of the drive shaft 309 is mounted in the storage space 311 formed by the pressing plate 306 and the mounting tool 308, and the mounting groove 312 formed in the mounting tool 308 is provided.
Attach the neck 309a of the drive shaft 309 to the
The rectangular contact surface 30 of the head 309c of the drive shaft 309
9b is brought into close contact with the lower surface of the pressing plate 306, so that there is no backlash between the driving shaft 309 and the pressing plate 306, and the pressing plate 306 can be smoothly moved up and down by the driving shaft 309. The four corners are supported by the guide pins 304 while maintaining a slight clearance.
Can be adjusted in inclination, and the pressing plate 30
Spring 307 for adjusting the inclination between the mounting plate 301 and the mounting plate 301
Is provided, for example, the pressing plate 306 is inclined by thermal deformation or the like so that each plunger 300
When the resin injection pressure into the cavities due to the above-mentioned variation is caused, the posture of the pressing plate 306 is adjusted by the urging force of the inclination adjusting spring 307, so that the resin injection pressure into each cavity is made uniform. be able to.

[0015]

As described above, according to the present invention, a plurality of cavities are formed between a pair of molds, a plurality of pots are respectively provided to communicate with these cavities, and the pots are inserted into these pots. A plurality of plungers are provided for extruding the compressed tablets into the respective cavities, and in a transfer molding die that simultaneously presses and drives these plungers, a pressing plate is supported on each of the plungers by a plurality of guide pins. The guide pins are provided so as to be capable of approaching and separating from the mold, and these guide pins are provided with a resilient member for urging the pressing plate in a direction for separating the pressing plate from the mold plate, and a drive shaft is detachable from the pressing plate. And the contact surface of the drive shaft with the pressing plate is formed in a rectangular shape, so that the driving shaft for moving the pressing plate has a rectangular shape. The contact surface suppresses rattling between the drive shaft and the pressing plate, and a resilient member provided on each guide pin moves the pressing plate while adjusting the position of the pressing plate, thereby reducing thermal deformation and the like. Even if this occurs, the pressing plate for driving the plunger can be moved smoothly and reliably, and the pressure for injecting the resin into each cavity can be made uniform.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention.

FIG. 2 is a sectional view showing an example of an upper die.

FIG. 3 is an explanatory diagram of FIG. 2 as viewed from a mating surface side.

FIG. 4 is a sectional view showing an example of a lower mold.

FIG. 5 is an explanatory view of FIG. 4 as viewed from the mating surface side.

FIG. 6 is a sectional view showing an example of a plunger unit.

FIG. 7 is a view taken along line VII-VII of FIG. 6;

FIG. 8 is a sectional view of a base end of the plunger.

[Explanation of symbols]

 Reference Signs List 10 Upper mold (mold) 20 Lower mold (mold) 207 Pot 300 Plunger 304 Guide pin 306 Press plate 307 Spring for tilt adjustment (elastic member) 309 Drive shaft 309b Contact surface

Claims (1)

(57) [Claims] 1. A plurality of cavities are formed between a pair of molds, a plurality of pots are provided in communication with the cavities, and a tablet loaded in the pots is extruded into the cavities. A plurality of plungers are provided, and in a transfer molding die that simultaneously presses and drives these plungers, a pressing plate is provided on each of the plungers so as to be supported by a plurality of guide pins so as to be able to approach and separate from the mold body. The guide pins are provided with a resilient member for urging the pressing plate in a direction to separate the pressing plate from the template, and a driving shaft is detachably connected to the pressing plate, and the driving shaft is A transfer molding die, wherein a contact surface with the pressing plate is formed in a rectangular shape.