JP3116702B2 - Mold press device and mold press method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold press apparatus and a mold press method for forming a molded body for sealing a chip mounted on a lead frame or a printed circuit board with a resin.

[0002]

2. Description of the Related Art For electronic components such as ICs and LSIs, a chip cut from a wafer is mounted on a lead frame or a printed circuit board, and wire bonding or the like is performed as necessary. It is manufactured by forming a mold body for protection.

A mold press device for forming a mold body includes an upper die and a lower die. The lower surface of the upper die and the upper surface of the lower die are joined to form a lower surface of the upper die and an upper surface of the lower die. The chip is positioned in the cavity, and in that state, the tablet (lumps of the raw material resin of the mold) stored in the tablet chamber formed inside the lower mold is heated and melted, and the molten resin is pushed up by the plunger. After pressurizing into the cavity through the runner and then holding the pressure for a certain period of time to cure the molten resin in the cavity, the upper mold and lower mold are separated, and the mold body is ejected from below with the ejector pins in the lower mold. The lead frame or printed circuit board on which the molded body is formed is taken out from the lower mold by pushing up.

As described above, as means for raising the plunger for press-fitting the molten resin into the cavity, there are mechanical up-and-down moving means using a motor, a feed screw, a nut, and the like, and isobaric means using a hydraulic cylinder. Various vertical movement means are known.

[0005]

A plurality of cavities and tablet chambers are formed in the lower mold and the upper mold, and the tablets in each of the tablet chambers are simultaneously melted and pressed into the cavities. However, since tablets have variations in dimensions (volume), the liquid pressure of the molten resin press-fitted into the cavities varies from cavity to cavity in the above-described mechanical up / down movement means, and variations in the quality of the mold body easily occur. There was a problem.

[0006] Further, in the case of a constant pressure vertical moving means using a hydraulic cylinder, the moving speed of each plunger varies due to variation in the magnitude of the sliding friction between the outer surface of the plunger and the inner wall surface of the tablet chamber. However, the liquid pressure of the molten resin press-fitted into the cavities may vary from one cavity to another, or in the worst case, a cavity may be insufficiently filled.

Accordingly, an object of the present invention is to provide a mold press apparatus and a mold press method capable of forming a high-quality mold body with no variation in quality with a high yield.

[0008]

For this purpose, a mold press apparatus according to the present invention comprises: an elevating means for elevating and lowering an upper mold and a lower mold; a plurality of tablet chambers formed in the lower mold;
A plurality of cavities formed on the opposing surfaces of the upper mold and the lower mold, and a runner communicating the cavities with the tablet chamber;
A mold formed by curing the molten resin in this cavity
An ejector pin pushing up the shield body, a plunger disposed in each tablet compartment, a plunger support member for supporting these plungers at the hydraulic, the flop
Servo that moves up and down the support member of the plunger and plunger
Lifting means consisting of a motor and the torque of this servomotor
Torque spike detection circuit for detecting spikes in
Comprising a pressure device for applying a fluid pressure is catcher supporting pressure, and control means for controlling the lift means and the pressure device, the pressure device
However, by changing the hydraulic pressure, the plunger and the
It can be rigidly connected to the plunger support member.
The control means further comprises: the plunger and the plunger support.
Holding the plunger support portion in a rigidly connected state with the holding member.
Raise the material and press the molten resin into the cabinet,
The torque spike detecting circuit detects a spike in torque.
After that, release the rigid connection state and fix the plunger support member
The lifting means and the pressurizing device are controlled so as to be pushed by the force of
Control .

[0009]

In the above arrangement, when the molten resin is pressed into the cavity, the plungers are pushed into the tablet chamber at the same moving speed. At the time of holding pressure, a uniform force is applied to each plunger by hydraulic pressure. Thus, it is possible to prevent the quality of the molded body from being varied.

[0010]

【Example】

(Embodiment 1) Next, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a front view of a chip mold press apparatus according to a first embodiment of the present invention. 1 is a base,
A lower mold 2 is provided on the upper surface. A pole 3 is erected at a corner of the base 1. A top plate 4 is provided above the pole 3, and a cylinder 5 is provided on the top plate 4. An elevating plate 7 is connected to the rod 6 of the cylinder 5, and an upper die 8 is mounted on a lower surface of the elevating plate 7. The end of the lifting plate 7 is slidably fitted to the pole 3. Reference numeral 20 denotes a lead frame disposed on the lower die 2, on which a plurality of chips P cut out from a wafer are mounted.

A plurality of cavities 9 are formed on the upper surface of the lower die 2, and a plurality of cavities 10 are formed on the lower surface of the upper die 8. When the rod 6 of the cylinder 5 projects and the upper die 8 descends, the lead frame 20 is sandwiched between the lower die 2 and the upper die 8, and the chip P is positioned in the cavities 9 and 10. When the rod 6 of the cylinder 5 is retracted, the upper die 8 moves up. Although not shown, the chip P
Are connected to the leads of the lead frame 20 by thin wires.

FIG. 2 is a partial sectional view of a chip mold press apparatus according to a first embodiment of the present invention. A block 11 is integrally incorporated in the lower mold 2, and a plurality of the cavities 9 are formed on an upper surface of the block 11. An ejector pin 12 penetrates vertically below each cavity 9. Each ejector pin 12 is a plate 1
3 stands on. The lower surface of the plate 13 is supported by a vertical rod 14. The rod 14 is driven up and down by a lifting device (not shown). A first pressure sensor 15 is provided at the lower end of one of the ejector pins 12. As described later, when the molten resin of the tablet 17 is pressed into the cavities 9 and 10, the liquid pressure is applied to the ejector pins 12, and the liquid pressure is applied to the first pressure sensor 15 provided on the plate 13. By detecting, the internal pressure of the cavities 9 and 10 is detected. After the molten resin pressed into the cavities 9 and 10 is cured,
When the rod 6 of the cylinder 5 is retracted and the upper die 8 rises to open the upper surface of the lower die 2, when the plate 13 is pushed up by the rod 14 in this state, all the ejector pins 12 rise and the cavity The molded body cured in 9 and 10 is pushed up and taken out from the lower mold 2.

In FIG. 2, a tablet chamber 16 is formed at the center of the block 11, and the tablet chamber 16 is formed.
The tablet 17 is housed inside. FIG. 3 is a partial plan view of the lower die of the chip mold press apparatus according to the first embodiment of the present invention. One cavity 16 communicates with one cavity 16. A plurality of tablet chambers 16 are formed in the block 11, and each has a plunger 18 as shown in a partial sectional view of the chip mold press apparatus of the first embodiment of the present invention in FIG. Each plunger 18 is connected to the upper end of a rod 19. Each rod 19 passes through the center of the plate 13, and the lower end is supported by a plunger support member 21.

In FIG. 7, the plunger support member 21
Is composed of a liquid chamber 22 and a hydraulic cylinder having a piston 23, and the lower end of each rod 19 is supported by the piston 23. Oil 24 is injected into each liquid chamber 22. These liquid chambers 22 communicate with each other by a pipe 21 b formed inside the plunger support member 21, and the pressure of the oil 24 in each liquid chamber 22 is equalized.
In FIG. 2, the plunger support member 21 has a feed screw 25
Is connected to the upper end. Nut 2 for feed screw 25
6 is screwed. A pulley 27 is provided integrally with the nut 26. Reference numeral 28 denotes a first servomotor, and a pulley 29 is mounted on a rotary shaft thereof. A belt 30 is adjusted between the pulley 27 and the pulley 29.
When the first servomotor 28 rotates forward, the nut 26 also rotates forward, and the feed screw 25 rises. Then, the plunger support member 21, the rod 19, and the plunger 18 also rise. When the first servomotor 28 rotates in the reverse direction, the plunger support member 21, the rod 19, and the plunger 18 move down. That is, the feed screw 25, the nut 26, the first servomotor 28, and the like constitute lifting / lowering means for causing the plunger 18 to perform a lifting / lowering operation. The servomotor 28 as the first lifting / lowering means moves the plunger 18 up and down. By controlling the rotation speed of the first servomotor 28, the lifting / lowering operation of the plunger 18 can be speed-controlled. .

In FIG. 2, reference numeral 31 denotes a pressurizing device which is installed inside the base 1 and controls the hydraulic pressure of the oil 24 in the plunger support member 21, and is configured as follows.
Reference numeral 32 denotes a cylinder in which the oil 24 is stored, in which a piston 33 is disposed. This cylinder 3
2 and the liquid chamber 22 are connected by a tube 34 and a conduit 21b (FIG. 7). The piston 33 is connected to the upper end of a vertical feed screw 35. A nut 36 is screwed into the feed screw 35, and a pulley 37 is
Are provided integrally. Reference numeral 38 denotes a second servomotor, and a pulley 3 is mounted on a rotation shaft of the second servomotor 38.
9 is mounted. A belt 40 is adjusted between the pulley 37 and the pulley 39. Therefore, when the second servomotor 38 rotates forward, the nut 36 rotates forward and the feed screw 35 rises. Then, the piston 33 rises, and the hydraulic pressure of the oil 24 increases. Further, the pressurizing device 31 enables the piston 23 and the plunger support member 21 to be rigidly connected to each other by changing the hydraulic pressure to the ultra-high pressure F1 or the low pressure F2, and to perform equal pressure control. To release the rigid connection state (details will be described later). Reference numeral 41 denotes a second pressure sensor which detects the hydraulic pressure of the oil 24. As shown in FIG. 7, the hydraulic pressure of the oil 24 applied from the pressurizing device 31 through the tube 34 acts on all the pistons 23 equally, so that equal pressure is applied to all the cavities 9 and 10. ing.

In FIG. 3, the cavity 9 and the tablet chamber 16 are connected by a runner 42 having a narrow groove shape.
The molten resin of the tablet 17 melted in the tablet chamber 16 is pressed into the cavity 9 through the runner 42. The junction between the cavity 9 and the runner 42 is a narrow gate 43.

FIG. 4 is a block diagram of a control system of the chip mold press apparatus according to the first embodiment of the present invention. The first pressure sensor 15 is connected to a cavity pressure detection circuit 51, and the second pressure sensor 41 is connected to a hydraulic pressure detection circuit 52. The cavity pressure detection circuit 51 and the hydraulic pressure detection circuit 52 are connected to a control circuit 53. The control circuit 53 includes a CPU, a ROM, a RAM, and the like.
The control circuit 53 controls a first drive circuit 54 that controls the first servo motor 28 and a second drive circuit 55 that controls the second servo motor 38. Also, the first drive circuit 5
4 is connected to a sudden increase in torque detection circuit 56, and the sudden increase in torque detection circuit 56 is connected to a control circuit 53. The first drive circuit 54 has a built-in torque monitor (not shown) for detecting and outputting the torque of the first servomotor 28. Detect a spike.
The description of the torque monitor is omitted because it is a known technique.

This chip mold press apparatus is configured as described above, and the operation will be described next. As shown in FIG. 1, a lead frame 20 on which a chip P is mounted is placed on the lower die 2. Next, the rod 6 of the cylinder 5 is projected to lower the upper die 8, and the lead frame 20 is sandwiched between the upper die 8 and the lower die 2. FIG. 2 shows the state at this time. However, in FIG. 2, the lead frame 20 and the chip P are omitted because the drawing becomes complicated.

In FIG. 2, a tablet 17 is stored in the tablet chamber 16 in advance, and the tablet 17 is heated and melted by a heater (not shown) built in the lower mold 2. The operation will be described below with reference to FIGS. FIG. 5 is a flowchart of the operation of the chip mold press apparatus according to the first embodiment of the present invention, and FIG. 6 is a time chart thereof. In FIG. 6, (a) shows the plunger 1
8, the position in the height direction of the upper surface, (b) is a rising speed of the plunger 18, (c) is a torque signal output from the torque monitor (corresponding to a load acting on the plunger 18), and (d) is a cavity pressure detecting circuit 51 Output cavity pressure,
(E) shows the hydraulic pressure output from the hydraulic pressure detection circuit 52 of the oil 24.

At time -αT in FIG. 6E, first, the second servomotor 38 is driven to raise the piston 33 of the cylinder 32, and the hydraulic pressure of the oil 24 in the liquid chamber 22 is set to the ultrahigh pressure F1. The piston 23 is pressed against the ceiling of the liquid chamber 22 and fixed to the plunger support member 21 (Step 1 in FIG. 5). Here, the ultrahigh pressure F1 is a pressure large enough to support each plunger 18 with a force stronger than the sliding resistance acting on each plunger 18 or the flow resistance of the molten resin. FIG. 7 shows the position of the piston 23 in the liquid chamber 22 at this time. When the oil 24 is press-fitted into the liquid chamber 22 from the cylinder 32, all the pistons 23 are pushed up and are placed on the ceiling of the liquid chamber 22. Pressed, the upper surfaces of all plungers 18 are at the same level. Thus, the ultra-high pressure F1
By strongly pressing the piston 23 against the ceiling of the liquid chamber 22, the plunger 18 and the plunger support member 21 are pressed.
Becomes substantially rigid.

Next, at a start time T0, the first servomotor 28 is driven at a high speed to raise each plunger 18 at a high speed (step 2). ) Is forcibly filled (see time T0 to T1 in FIG. 6A). At this time, the speed of the first servomotor 28 is controlled so that the rising speed of each plunger 18 becomes a predetermined speed. Here, in FIG.
When reaching the gate 43 at the tip of No. 2, the load acting on the plunger 18 rises sharply because the gate 43 is narrow (see the torque signal a in FIG. 6C). Then, the suddenly increased torque signal a is detected by the torque suddenly increasing detection circuit 56 (FIG. 4) and is inputted to the control circuit 53 (Step 3 in FIG. 5). Then, the control circuit 53 switches the rotation speed of the first servomotor 28 from high speed to low speed, and thereafter raises each plunger 18 at low speed (see step 4 and times T1 to T2 in FIG. 6B). Then, as shown in time T1 to T2 in FIG. 6A, each plunger 18 rises slowly, and each cavity 9, 10 is gradually filled with the molten resin. As described above, the plunger 18 is raised at a low speed to slowly press the molten resin into each of the cavities 9 and 10, thereby preventing the wire connecting the chip P and the lead frame 20 from falling down due to the flow of the molten resin. Then, the molten resin is sufficiently spread in the cavities 9 and 10. Of course, also in this case, the first servomotor 28 is driven by speed control so as to have a predetermined speed (low speed). In addition, since each plunger 18 is rigidly connected to the plunger support member 21, the moving speed of each plunger 18 matches without variation.

When the cavities 9 and 10 are filled with the molten resin, the internal pressure of the cavities 9 and 10 rises rapidly (FIG. 6).
(See (b) at time T2 in (d).) This rapid increase in the internal pressure is detected by the first pressure sensor 15. Further, the rapid rise of the internal pressure is detected as a torque signal c that rapidly rises in FIG. 6C (step 5 in FIG. 5). Then, the rise of the plunger 18 by the first servomotor 28 is stopped by the torque signal c (time T in FIG. 6B).
2) Thereafter, the pressure holding of the cavities 9 and 10 is performed (time T2 to T3 in FIG. 6A). In this case, FIG.
As shown in (e), at this time T2, the plunger support pressure by the second servomotor 38 is reduced from the ultrahigh pressure F1 to a desired pressure (low pressure F2) (step 6 in FIG. 5). By changing the hydraulic pressure of the oil 24 from the ultra-high pressure F1 to the low pressure F2, each piston 23 held in the plunger support member 21 in the rigidly connected state is released from the rigidly connected state. As a result, a state in which the pressure of the molten resin in each of the cavities 9 and 10 can be evenly applied by the liquid pressure of the oil 24 is achieved. Then, the plunger support member 21 is pushed upward by the force f1 (see FIG. 8) by driving the first servomotor 28 with a torque suitable for holding pressure (step 7 in FIG. 5). And this force f1 is
The liquid pressure is evenly distributed to the pistons 23 and the plungers 18 press the molten resin evenly (equal pressure control). FIG. 8 is a partial cross-sectional view of the chip mold press apparatus according to the first embodiment of the present invention, showing a state where the above-mentioned pressure holding is performed. The height of the upper surface of each plunger 18 varies due to variations in the volume of the molten resin 17a. When a predetermined time (generally about 40 seconds) has elapsed and the molten resin 17a has been cured (step 8 in FIG. 5), the upper die 8 is raised in FIG. 2 to open the upper surface of the lower die 2 (FIG. 5). Step 9) Also, raise the rod 14 to raise each ejector pin 12 (Step 1 in FIG. 5).
0), if the mold body formed by the curing of the molten resin in each of the cavities 9 and 10 is pushed up and the lead frame 20 is taken out from the lower mold 2, a series of steps is completed.

The dashed line L in FIG. 8 shows the position of the upper surface of each plunger 18 when the sudden increase in torque signal c is detected. From the initial position shown in FIG. 7 to the position shown in FIG. 8, since the hydraulic pressure of the oil 24 is set to the super high pressure F1, each plunger 18 rises at the same speed by driving the first servomotor 28. Therefore, each plunger 1
It is possible to prevent the plunger 18 from rising at a different speed due to a variation in frictional resistance between the outer peripheral surface of the plunger 8 and the inner wall surface of each tablet chamber 16, thereby preventing the plunger 18 from varying in height. Thereafter, the hydraulic pressure of the oil 24 is reduced to the low pressure F2 so that the respective plungers 18 can be controlled under the same pressure, so that the molten resin 17a in all the cavities 9 and 10 can be uniformly pressurized and maintained. As described above, the mold press apparatus for the chip uses the runner 4
2 is filled with the molten resin (time T0 to T1), the first servomotor 28 is controlled at a high speed while the hydraulic pressure of the oil 24 is set to the super-high pressure F1, and the cavities 9 and 1 are controlled.
While filling the molten resin at 0 (T1 to T2 in FIG. 6A)
Controls the speed of the first servomotor 28 so as to control the speed of the oil 24, and if the fact that the cavities 9 and 10 are full of the molten resin is detected as a rapidly increasing torque signal c, The hydraulic pressure is set to the low pressure F2 so that each plunger 18 can be supported at an equal pressure by the hydraulic pressure of the oil 24, and during the time T2 to T3, all the cavities 9 and 10 are subjected to the equal pressure control suitable for holding pressure. As described above, the first servomotor 28 is controlled in torque, so that a high quality molded body can be formed with a high yield.

(Embodiment 2) FIG. 9 is a partial sectional view of a chip mold press apparatus according to a second embodiment of the present invention. FIG. 9 corresponds to FIG. 7 of the first embodiment. In FIG. 7, the internal pressure of the liquid chamber 22 is set to the super-high pressure F1, so that the plunger support pressure by the second servomotor 38 is increased. (See T0 to T2 in FIG. 6E). However, in the second embodiment, the internal pressure of the hydraulic pressure 22 is extremely reduced as shown by the broken line in FIG.
3), each piston 23 is grounded to the bottom of the liquid chamber 22 as shown in FIG. Therefore, this one also
9 and the feed screw 25 can be substantially rigidly connected. In this state, each plunger 18 is raised in the same manner as in the first embodiment until a sudden torque increase signal c is detected. When the sudden torque increase signal c is detected, the hydraulic pressure of the oil 24 is increased to a low pressure F2. Thereafter, the pressure is maintained in the same manner as in the first embodiment. In this case, the same effect as in the first embodiment can be obtained. In the first and second embodiments, the sudden increase in torque detection signal c is detected in step 5 of FIG. 5, but the pressure increase signal b output by the cavity pressure detection circuit 51 (FIG. 6D). May be detected. Further, in FIG. 6, a time T at which the torque sudden increase signal a is generated
If it is possible to predict in advance 1 and the time T2 at which the torque sudden increase signal c is generated, steps 3 and 5 in FIG. 5 are deleted, and when the time T1 is reached, the rising speed of each plunger 18 is reduced, and When it comes to oil 24
The control method may be changed so that the hydraulic pressure of the control unit becomes the low pressure F2.

[0025]

As described above, according to the chip mold press apparatus and mold press method of the present invention,
Press the molten resin sufficiently into the upper and lower mold cavities,
Moreover, after the press-fitting, all the cavities can be maintained at an appropriate constant pressure, so that a high-quality mold body having uniform quality can be formed with high yield.

[Brief description of the drawings]

FIG. 1 is a front view of a chip mold press apparatus according to a first embodiment of the present invention.

FIG. 2 is a partial sectional view of the chip mold press apparatus according to the first embodiment of the present invention.

FIG. 3 is a partial plan view of a lower die of the chip mold press apparatus according to the first embodiment of the present invention.

FIG. 4 is a block diagram of a control system of the chip mold press apparatus according to the first embodiment of the present invention.

FIG. 5 is a flowchart of the operation of the chip mold press apparatus according to the first embodiment of the present invention.

FIG. 6 is a time chart of the operation of the chip mold press apparatus according to the first embodiment of the present invention.

FIG. 7 is a partial sectional view of the chip mold press apparatus according to the first embodiment of the present invention.

FIG. 8 is a partial sectional view of the chip mold press apparatus according to the first embodiment of the present invention.

FIG. 9 is a partial sectional view of a chip mold press apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

 2 Lower die 5,32 Cylinder 8 Upper die 9,10 Cavity 16 Tablet room 17 Tablet 18 Plunger 21 Plunger support member 22 Liquid chamber 28 First servomotor 31 Pressurizing device 42 Runner 56 Torque sudden rise detection circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B29C 45/02 B29C 45/76 H01L 21/56

Claims (2)

(57) [Claims] An elevating means for elevating and lowering the upper die and the lower die relative to each other; a plurality of tablet chambers formed in the upper die and the lower die; A plurality of cavities formed on the facing surfaces of the mold and the lower mold, and a runner for communicating the cavities with the tablet chamber;
A mold formed by curing the molten resin in this cavity
An ejector pin for pushing up the plunger body, a plunger disposed in the tablet chamber, a plunger support member for hydraulically supporting the plungers, and a plunger.
Servomotor for raising and lowering the plunger and plunger support member
And lifting means comprising a suddenly above the torque of the servo motor
Rapid rise detection circuit for detecting rise and plunger support
Comprising a pressure device for applying a fluid pressure which is the pressure, and control means for controlling said pressure device and said elevating means, said pressure device
However, by changing the hydraulic pressure, the plunger and the
It can be rigidly connected to the plunger support member.
The control means further comprises: the plunger and the plunger support.
Holding the plunger support portion in a rigidly connected state with the holding member.
Raise the material and press the molten resin into the cabinet,
The torque spike detecting circuit detects a spike in torque.
After that, release the rigid connection state and fix the plunger support member
The lifting means and the pressurizing device are controlled so as to be pushed by the force of
A mold press device characterized by controlling . 2. A mold press apparatus according to claim 1,
Mold press method, wherein the hydraulic pressure is increased by driving the pressurizing device.
The plunger and the plunger support member are rigidly connected.
And the servomotor is operated at high speed while maintaining the rigid connection state.
By driving, the plunger support member and the front
Raise the plunger at high speed
Forcibly filling the runner with molten resin
And that the load acting on the plunger has risen sharply.
If the torque sudden rise detection circuit detects
Switch the rotation speed of the motor from high speed to low speed.
Slowly raise the plunger into the cavity
Gradually filling the molten resin; and filling the cavity with the cavity filled with the molten resin.
If it is detected that the internal pressure of the
Stops raising the plunger by driving the servo motor
And the plunger support member is moved by the pressurizing device.
By lowering the applied pressure from the high pressure to the low pressure
The rigid state is released, and thereafter, the melting in the cavity is performed.
Step of holding pressure while applying uniform pressure to the molten resin
And the molten resin in the cavity hardens after the possession time elapses
Then, open the upper surface of the lower mold and
The molding formed in the cavity by raising the pin
Removing the mold body from the lower die .