JPH0250813A - Transfer mold device - Google Patents

Abstract

PURPOSE:To enable injection speed and injection pressure to be precisely controlled, while the weight change of tablet is corrected without enlarging a device by a method in which while the group of plungers are supported on piston rods by way of a train of oil pressure cylinder chamber, the pressure-regulating circuit capable of switching is connected to the oil pressure cylinder chamber. CONSTITUTION:Pellet 32 is received in each cavity 3, and a cylinder block 18 is pushed upward by a piston rod 14. Then the inner pressure in each small cylinder chamber 19 is regulated into maximum injection pressure, whereby since each plunger 8 is controlled in such a state that each plunger 8 is integrally moved with the rising of the cylinder block 18, each plunger 8 is surely moved integrally with the stroke of the piston rod 14. By each small cylinder chamber 19 connected in a train by a communicating path 20, the weigh change of tablet 7 is corrected with the stroke of each plunger 8, and the resin is uniformly injected into each cavity 3.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to transfer molding technology, particularly a so-called multi-pot type molding method having a plurality of pots for feeding molding material to a group of cavities. The present invention relates to a transfer molding apparatus, and relates to an apparatus that is useful for molding resin-sealed pancakes, for example, in the manufacturing process of semiconductor devices.

[Conventional technology]

Generally, when molding a resin-sealed package in the manufacturing process of semiconductor devices, a lead frame is placed between the upper and lower molds of the mold so that the pellet fits inside the cavity, and the lead frame is inserted between the upper and lower molds. A transfer molding device is used to mold a package by injecting resin as a molding material into a tee.

As such a transfer molding device,
As described in Japanese Patent No. 7-123222, a plurality of pots for feeding molding material to a plurality of cavities formed in the mating surfaces of an upper mold and a lower mold, and each pot. a plunger slidably fitted into each of the plungers and configured to pump the molding material;
and a hydraulic cylinder device for advancing and retracting this group of plungers, each of the plungers being elastically supported by a screw I/rod in the hydraulic cylinder device via an elastic member such as a spring. There is.

According to such a transfer molding device, if there is a variation in weight between the tablets placed in each pot, the variation is absorbed by the flexure of the elastic material provided in each plunger. Therefore, regardless of variations in tablet weight, resin (hereinafter referred to as
It's called resin. ) will be pumped equally into each cavity.

[Problem to be solved by the invention]

However, the inventors have discovered that the i-transfer molding device having the above structure has the following problems.

(1) Since each plunger is elastically and independently suspended in the piston loft of the hydraulic cylinder, the movement of the piston rod is not directly transmitted to each plunger, making it difficult to precisely control injection speed, injection pressure, etc. be.

(2) If there is a difference in tablet weight, the difference is absorbed by the flexural deformation of the spring, but a difference occurs in the return force of the spring. In order to reduce this, it is necessary to reduce the spring constant, but if the spring constant is set to a small value, the spring length becomes large, which increases the size of the entire transfer molding apparatus.

An object of the present invention is to provide a transfer molding device that can correct variations in tablet weight without increasing the size of the device, and can precisely control injection speed and injection pressure.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means to solve the problem]

An overview of typical inventions disclosed in this application is as follows.

That is, there are a plurality of pots for feeding molding material to a plurality of cavities formed in the mating surfaces of the upper mold and the lower mold, and a plurality of pots that are slidably fitted into the respective pots, and the molding material is slidably fitted into each pot. In a transfer molding device comprising a plunger configured to force-feed material and a hydraulic cylinder device for moving the plunger group forward and backward, the plunger group is connected to a piston rod of the hydraulic cylinder device by a series of hydraulic cylinders. The hydraulic cylinder chamber is supported through a chamber, and a pressure adjustment circuit capable of changing the adjustment pressure is connected to this hydraulic cylinder chamber.

[Effect]

After a predetermined number of tablets are placed in each pot and the upper and lower molds are clamped, a group of plungers is advanced within each pot by a hydraulic cylinder device.

At this time, the pressure in the cylinder chamber interposed between the piston rod of the hydraulic cylinder device and each plunger group is set by the pressure adjustment circuit to be slightly larger than the operating pressure for pushing up the piston rod in the hydraulic cylinder device. There is. Therefore, the plunger groups each supported by the piston rod via the cylinder chamber are in a state equivalent to being supported by the piston rod as a single rigid body. In other words, since the plunger group is treated as a single rigid body, the plunger group faithfully responds to the upward movement of the screw rod. the result,
Although the plunger group is supported through a cylinder chamber, it is precisely controlled.

When the plunger group is advanced by the hydraulic cylinder device to each pot just before the final stage of the resin injection stroke, the pressure in the cylinder chamber is set by the pressure adjustment circuit to be slightly lower than the operating pressure of the hydraulic cylinder device. be done. Each plunger is pushed back by a difference in tufflet height, each depending on the variation in tablet weight.

Due to the amount of pushback that varies appropriately for each plunger,
Variations in tablet weight will be relatively absorbed. As a result, resin is evenly injected into each cavity regardless of variations in tablet weight.

[Example] Fig. 1 is a side sectional view of a transfer molding device according to an embodiment of the present invention at the final stage of the pumping process, Fig. 2 is a side sectional view of the same in the middle of the pumping process, and Fig. 3 is a side sectional view of the transfer molding device in the final stage of the pumping process. Figure II
[It is a partially omitted front sectional view taken along line -I.

In this embodiment, the transfer molding apparatus according to the present invention is configured to mold a resin-sealed package of a semiconductor integrated circuit device (hereinafter referred to as IC), and an upper mold 1 and a lower mold are molded together. It is equipped with 2.

A plurality of cavities 3 for molding a resin-sealed package are formed on the mating surface of the upper mold 1 and the lower mold 2, and a plurality of pots 4 are regularly formed on the mating surface of the lower mold 2. They are arranged so that they pass through each other vertically. The pot 4 and the cavity 3 are fluidly connected by a runner 5, and a gate 6 is provided at the connection between the runner 5 and the cavity 3 so that the resin can be effectively injected into the cavity 3. It is formed.

The pots 4 are formed into a substantially cylindrical hollow shape so as to accommodate the tablets 1-7 formed by compacting powdered resin into a substantially cylindrical shape, and each pot 4 is provided with a plunger 8.
are inserted from below so as to be slidable in the vertical direction.

A hydraulic cylinder device 10 is installed directly below the lower mold 2 in a vertically upward direction.
2, a piston 13 fitted in the cylinder chamber 12 so as to be slidable downward, and a piston 13 that is connected to the piston 13 so as to move integrally therewith and protrudes vertically upward. a hydraulic circuit 15 that supplies and discharges pressure oil to and from the cylinder chamber 12; a controller 16 that controls the hydraulic circuit 15;
The piston rod 14 is equipped with a measuring device 17 that measures the stroke speed and the amount of flow.

The controller 16 is configured to control the stroke operation of the piston rod 14 by controlling the hydraulic circuit 15 based on the measurement data of the measuring device 17.

A cylinder block 18 is attached to the upper end of the piston rod 14.
The block 18 is formed so as to be enlarged in the horizontal direction and move integrally, and this block 18 is formed with a plurality of small cylinder chambers 19 arranged to correspond to each of the plungers 8.

These small cylinder chambers 19 are fluidly connected to each other in series by a communication passage 20, and a pressure regulating circuit 21 is connected to the communication passage 20.

This pressure adjustment circuit 21 is equipped with a pressure control valve and the like, and is configured to be able to switch and adjust the internal pressure of each small cylinder chamber 19 in two stages through the communication path 20. and,
A screw 1-22 is fitted into each small cylinder chamber 19 so as to be slidable in the vertical direction, and the plunger 8 is connected to each piston 22 via a piston rod 23 so as to move integrally therewith. There is.

Note that the workpiece 30 is a workpiece, in which a pellet 32 in which an integrated circuit is built is bonded to a lead frame 31, and the lead frame 31 and pellet 3 are bonded together.
A wire 33 is bridged between the two.

Next, the action will be explained.

When the tablet 7 is thrown into the pound 4, the piston rod 14 of the hydraulic cylinder device Tr], O is lowered, so the plunger 8 supported by the piston rod 14 via the cylinder block 18 is moved into the pond 4. 4
is located at the bottom of the. At this time, the small cylinder chamber 19
The internal pressure of each plunger 8 is constantly adjusted by the pressure adjustment circuit 21 through the communication passage 20 so that the pressure approximately corresponds to the maximum injection pressure. They are each supported by the cylinder block 18 via the rod 23 like a single rigid body that moves integrally with the cylinder block 18 .

Tablet 7 is put into each pot 4 "l" 16
A workpiece 30 is placed between the upper die 1 and the lower die 2, and the pellet 3
2 are arranged and held so as to be accommodated in each cavity 3, and then pressure oil is supplied to the cylinder chamber 11 by the hydraulic circuit 15 of the hydraulic cylinder device 10. As a result, the cylinder block 18 is pushed up by the piston rod 14, so that each plunger 8 moves forward inside the pot 4, and the resin, which has been heated and melted in the pot 4 and becomes liquid, is transferred via the runner 5. It is injected into each cavity 3 from the gate 6.

At this time, each small cylinder chamber 1 is
9 is adjusted to the maximum injection pressure, each plunger 8 is controlled to move in unison with the rise of the cylinder block 18, so each plunger 8 faithfully moves in unison with the stroke of the piston rod 14. I will have to move. Therefore, the controller 16 can precisely control the stroke operation of each plunger 8 by feedback-controlling the hydraulic circuit 15 based on the measurement data of the measuring device 17 that measures the stroke status of the piston rod 14.

As a result, injection of resin into each cavity by each plunger 8 is controlled with great precision and precision.

By the way, since the tablets 7 are formed by compacting powdered resin, the weight of each tablet tends to vary.

If there are variations in tablet weight, if resin is pumped with the same stroke for each plunger, the larger the weight of the tablet, the larger the amount of resin injected, and when the injection ends at the cavity corresponding to the maximum injection amount. Since the hydraulic cylinder device stops pumping the remaining plungers, defects such as unfilled cavities occur in the remaining cavities.

Therefore, in this embodiment, when the eight groups of plungers are advanced by the hydraulic cylinder device 10 to just before the final stage of the resin pumping stroke, the pressure in the small cylinder chamber 19a is controlled by the pressure adjustment circuit 21 to be lower than the maximum injection operating pressure. can also be switched to become smaller. This switching timing is detected by the measuring device 17.

When the pressure is switched, in the pot 4 where the weight of the tablet is relatively large, the piston 22 connected to the plunger 8 is pushed back greatly against the internal pressure of the small cylinder chamber 19 because the tablet height is high. Then, the small cylinder chamber 19 is retreated.

On the other hand, in case 1-4, where the weight of the tablet is small, since the tablet height is low, the piston 22 connected to the plunger 8 is pushed back against the internal pressure of the small cylinder chamber 19, and is pushed back into the small cylinder chamber 19. The amount of retraction is smaller than that of the former.

In this way, according to the present embodiment, variations in the weight of the tablet 7 are corrected by the stroke of each plunger 8 due to the small cylinder chambers 19 connected in series through the communication path 20. The resin is evenly injected into each. As a result, complete filling of all cavities 3 is ensured.

Here, correction for the weight variations of the tablets 7 is realized by free deformation of the pressure oil in each small cylinder chamber 19, so the entire transfer molding device becomes larger compared to the conventional example in which correction is made by deflection deformation of a spring. It can be suppressed from doing so. In other words, when setting a large amount of correction due to the deflection deformation of the spring,
By setting a large spring length, it is necessary to set a small spring constant, which increases the size of the entire transfer molding apparatus. However, as in this embodiment, when increasing the amount of correction due to free deformation of the pressure oil in the cylinder chamber, it is only necessary to increase the length of each small cylinder chamber by the amount of correction, and the length of the increase The amount of increase is extremely small compared to the amount of increase caused by setting the constant small.

According to the embodiment described above, the following effects can be obtained.

(1) By supporting the plunger group on the piston rod of the hydraulic cylinder device through a series of cylinder chambers and by connecting a pressure adjustment circuit to this hydraulic cylinder chamber, the pressure in the cylinder chamber can be increased when resin is injected. By adjusting the plunger group, it is possible to substantially integrate the plunger group with the screws 1 to 1, so that the movement of the piston rod can be directly transmitted to the plunger group, and as a result, resin injection by the plunger group can be Speed, injection pressure, etc. can be controlled accurately and precisely.

(2) In addition, by adjusting the pressure in the cylinder chamber to be small just before the final stage of the resin injection process, it is possible to move each plunger to a state where it is substantially independently suspended by the pressure oil in the cylinder chamber. Therefore, the free deformation of the pressure oil in the cylinder chamber can absorb the variation in weight to the tabreso 1, and as a result, the amount of resin poured into the cavity by each plunger can be equalized, and the amount of resin poured into each cavity can be equalized. Appropriate filling can be achieved.

(3) When the variation in tablet weight is absorbed by the free deformation of the pressure oil in the cylinder chamber, and the correction amount for the variation is set to a large value, the length of the cylinder chamber in the stroke direction is adjusted by the increase in the correction amount. Therefore, the increase in size of the entire transfer molding apparatus can be suppressed to a minimum.

The invention made by the inventor of Wood has been specifically explained based on the examples above, but it goes without saying that the present invention is not limited to the examples described above, and can be modified in various ways without departing from the gist thereof. Nor.

For example, the plunger is not limited to being fitted into the cylinder chamber via a screw rod and piston, but may also be structured so that the lower end of the plunger is fitted directly into the cylinder chamber. good.

The pot and the plunger are not limited to being disposed on the lower mold, but may be disposed on the upper mold, and the hydraulic cylinder device may be disposed facing downward according to the arrangement of the plunger.

In the above explanation, the invention made by the present inventor was mainly applied to a 1-transfer molding device for molding a resin-sealed package for an IC, which is the field of application in which the invention was made by the present inventor, but the invention is limited thereto. transfer molding equipment for molding resin-sealed packages for electronic components and electronic equipment, as well as various resin products, especially transfer molding equipment in general where products are molded using multiple pots and plungers. It can be applied to

〔Effect of the invention〕

A brief explanation of the effects obtained by typical inventions disclosed in this application is as follows.

The plunger group is supported by the piston rod of the hydraulic cylinder device through a series of cylinder chambers, and the pressure in the cylinder chamber is adjusted to be large when resin is injected.
Since the plunger group can be substantially integrated into the piston rod, the movement of the piston rod can be directly transmitted to the plunger group, and as a result, resin injection status by the plunger group can be precisely controlled. . In addition, by adjusting the pressure in the cylinder chamber to a low level just before the final stage of the resin injection process, each plunger can be moved to an independently suspended state by the pressure oil in the cylinder chamber. Due to the free deformation of the pressure oil, variations in the weight of the cube can be absorbed, and as a result, the resin injection pressure and injection amount into the cavity by each plunger can be equalized.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view showing a 1-transfer molding device which is an embodiment of the present invention at the final stage of the pumping process, Fig. 2 is a side sectional view in the middle of the pumping process, and Fig. 3 is the same as that of Fig. 1. ■
It is a partially omitted front sectional view taken along the line -■. 1..." 2nd mold, 2...lower mold, 3...cavity 4...18~ pot, 5...runner, 6...gate, 7...tablet, 8... Plunger, 10... Hydraulic cylinder device, 11... Main body, 12... Cylinder chamber, 13
...Piston, 14...Piston rod, 15...
- Hydraulic circuit, 16... Controller, 17... Measuring device, 18... Cylinder block, 19... Small cylinder chamber, 20... Communication path, 21... Pressure adjustment circuit,
22... Piston, 23... Piston rod, 30
...Work, 31...Lead frame, 32...
Pellet, 33...wire.

Claims (1)

[Claims] 1. A plurality of pots for feeding molding material to a plurality of cavities formed on the mating surfaces of the upper mold and the lower mold, and a slidable member for each pot. A transfer molding device comprising plungers that are fitted into each other and configured to force-feed the molding material, and a hydraulic cylinder device for moving the plunger group forward and backward, the plunger group being connected to the hydraulic cylinder device. A transfer molding apparatus characterized in that the piston rod is supported by a series of hydraulic cylinder chambers via a series of hydraulic cylinder chambers, and a pressure adjustment circuit capable of switching the adjustment pressure is connected to the hydraulic cylinder chambers. 2. The transfer molding device according to claim 1, wherein a control device for controlling the forward speed of the plunger is interposed in the hydraulic circuit of the hydraulic cylinder device.