JPH09312309A - Molding method, mold unit, and tablet - Google Patents

Abstract

(57) Abstract: In a mold unit, it is possible to prevent an inner lead short circuit, a package crack, and wear of a movable part of a molding device due to tablet powder. SOLUTION: A mold part M for performing semiconductor mold molding
In the transport system C that transports the tablet 11 to the pot 10 of
A brushing device 13 for sweeping the tablet powder adhering to the surface of the tablet 11 with a brush 28, an air cleaning device for sucking the tablet powder adhering to the tablet 11 and the tablet carrier 16 for putting the tablet 11 into the pot 10 under a negative pressure. 18 is installed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding technique for molding a resin molded product, and more particularly to a technique effective when applied to semiconductor molding for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art In a semiconductor device manufacturing process, after a semiconductor chip is mounted on a lead frame and wire-bonded, the semiconductor chip and the wire are protected from external atmosphere such as dust and humidity and mechanical shock. For ease of handling, these are sealed with a resin, for example. In this molding technique, a lead frame on which a semiconductor chip is mounted is set in a lower mold heated to about 180 ° C., and the mold is clamped.
Pressure is applied by a plunger to a tablet placed in a pot, which is a heating chamber, and the tablet is filled into a cavity and cured. And today, this mold sealing with excellent mass productivity is, for example, DIP (Dual in-Line Package)
It is used for sealing many insert-type or surface-mount type semiconductor devices such as QFPs (Quad Flat Packages).

[0003] Examples of detailed description of the technology of mold sealing include, for example, "Electronic Materials", August 1987 (issued on August 1, 1987), published by the Industrial Research Council, p. There is a P79, in which a multi-cavity single plunger type transfer mold apparatus with a plurality of runners extended is disclosed.

[0004] Here, a tablet put into a pot of a molding apparatus is formed by melting and kneading powders of various materials such as an epoxy resin, a phenol resin (curing agent), a filler, a catalyst (promoter), and a release agent. As a result, the powder (hereinafter referred to as “tablet powder”) adheres to the surface of the completed tablet.

The tablet to which the tablet powder supplied from the tablet supply unit adheres is put into the pot of the molding apparatus by the tablet carrier.

[0006]

Here, when the tablet is put into the pot according to the above-described procedure, the tablet powder scatters and accumulates in the molding apparatus.

[0007] If tablet powder that has been deposited and solidified falls on the inner lead during molding, the inner lead is deformed due to this when the mold is clamped and comes into contact with other inner leads, resulting in a short circuit inside the package. Occurs. It is also said that such a short circuit of the inner lead caused by the tablet powder accounts for about 30% of the entire short circuit failure.

When a mass of tablet powder is taken in and molded, cracks occur at the boundary between two materials having different thermal histories, ie, a molten mold resin and a deposited tablet powder. In recent years, package cracks due to tablet powder are more likely to occur in the trend of thinner packages, which may significantly impair product reliability.

Furthermore, since the composition of the filler, which accounts for about 2/3 of all the components of the tablet, is silicon, the wear of the movable part of the molding apparatus to which the tablet powder adheres is rapidly accelerated and the life of the apparatus is shortened. Become.

Accordingly, an object of the present invention is to provide a technique capable of preventing a short circuit of an inner lead caused by tablet powder.

Another object of the present invention is to provide a technique capable of preventing a package crack caused by tablet powder.

Still another object of the present invention is to provide a technique capable of preventing abrasion of a movable portion of a molding apparatus due to scattering of tablet powder.

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

[0014]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

That is, the molding method according to the present invention is
It is characterized in that the tablet powder adhering to the surface of the tablet is removed before the tablet is put into the pot of the molding apparatus for semiconductor molding.

In this case, the tablet powder can be removed by using at least one of the stripping force by the injection of high-pressure gas, the brush sweeping force, the adhesive force of the adhesive material, and the negative pressure suction force. .

Further, the mold unit according to the present invention is
First tablet powder removing means for sweeping tablet powder adhering to the surface of the tablet with a brush, a tablet, and the tablet and the tablet into a pot in a transport system for transporting the tablet to a pot of a molding apparatus for semiconductor molding Second tablet powder removing means for sucking the tablet powder attached to the tablet carrier under negative pressure, with the central axis set parallel to the central axis of the tablet and the adhesive outer peripheral surface in contact with the outer peripheral surface of the tablet. A cylindrical third tablet powder removing means that rotates around the central axis to remove tablet powder from the tablet, a blow chamber through which the tablet passes, and a tablet that has a high-pressure gas jetted to the tablet in the blow chamber and adheres to the surface of the tablet. The fourth consisting of a nozzle for removing powder and a dust collector for sucking the removed tablet powder At least one of the tablet dust removing means of the tablet dust removing means is characterized in that is installed.

A cleaner for sucking and removing the tablet powder adhering to the brush can be installed in the first tablet powder removing means in this mold unit.

Further, the tablet according to the present invention is formed by compressing and hardening a thermosetting resin into a predetermined shape, plasticizing it, and press-fitting it into the cavity of a mold to mold a semiconductor chip. The surface is coated with a coating material. Carnauba wax, Hoechst wax or polyethylene can be used as the coating material.

According to the above-mentioned means, since the tablet powder is removed in advance before dropping the tablet into the pot,
Alternatively, since the coating material prevents the tablet powder itself from being generated, the tablet powder is not brought into the molding device.

Therefore, it is possible to prevent a short circuit defect due to the inner lead deformation caused by the tablet powder. Also, package cracks due to two resins having different thermal histories can be prevented, and the quality of the mold can be improved. Furthermore, wear of the movable part of the molding apparatus due to the adhesion of the tablet powder is prevented, and the life of the apparatus can be extended.

[0022]

Embodiments of the present invention will be described below in detail with reference to the drawings. In all the drawings for describing the embodiments, members having the same functions are denoted by the same reference numerals, and the repeated description thereof will be omitted.

(Embodiment 1) FIG. 1 is a schematic view showing a mold part of a mold unit according to an embodiment of the present invention, and FIG. 2 shows a carrying system for carrying tablets to the mold part of FIG. Schematic diagrams, FIGS. 3 and 4 are explanatory views showing a part of the transport system of FIG. 2 in an enlarged manner.

A molding part (molding device) M according to the present embodiment shown in FIG. 1 is a multi-plunger type transfer molding device, and is provided above a lower mold 1 on which a lead frame on which a semiconductor chip is mounted is installed. An upper die 2 for joining the lower die 1 and clamping the lead frame is located. However, the present invention can be applied to other molding apparatuses such as a single plunger type molding apparatus, and is not limited to the above-described apparatus.

The lower mold 1 is on the base 3 and the upper mold 2 is on the movable platen 4.
The movable platen 4 moves down along the guide 5 and the upper and lower dies 1 and 2 are clamped. Mold 1,2
The heaters 6 are respectively buried in the dies, and molds 1 and 2 are heated to, for example, 180 ° C. Plungers 9 that move up and down by a hydraulic cylinder 8 are provided at a plurality of positions on a fixed platen 7 located above the movable platen 4, and the lowered plunger 9 press-fits the plasticized tablet put into the pot into the cavity. Thus, a semiconductor chip is molded, that is, semiconductor molding is performed. For simplification of the drawing, only one plunger is shown in FIG.

FIG. 2 shows a carrying system C for carrying the tablets 11 to the pot 10 of the mold section M.
The tablet 11 is obtained by compressing and hardening a thermosetting resin into, for example, a column shape, and as described above, a tablet powder is attached to the surface thereof. The transport system C that transports the tablets 11 sequentially aligned and delivered from the parts feeder 12 to the mold section M includes a brushing device (first tablet powder removing means) 13 and a tablet 11 from the brushing device 13. A first conveyor 14 for transferring the tablet 11, a second conveyor 15 for receiving the tablet 11 from the first conveyor 14 and further transferring the tablet 11, and a tablet 11 transferred to the second conveyor 15 to the pot of the upper mold 2. It is composed of a tablet carrier 16 to be loaded into the container 10. An air cleaning device (second tablet powder removing means) 18 is installed corresponding to the tablet carrier 16.

As shown in FIG. 3, a brushing device 13
Is composed of a brush 28 in which a brush portion 28b is formed on the outer periphery of a roller 28a which rotates around a central axis, and a brush cleaner 29 which removes tablet powder adhering to the rotating brush portion 28b. The tablet powder is removed by sweeping the entire circumference of the tablet 11 with the brush portion 28b. The brush part 2
Although horsehair that flexes well is used for 8b, various other things such as pig hair and artificial hair made of nylon can also be applied.

As shown in FIG. 2, the first and second conveyors 14 and 15 are provided with a carrier arm 26 for carrying the tablet 11 toward the upper mold 2. As a result, the tablet 11 from the brushing device 13
Are transferred from the first conveyor 14 to the second conveyor 15 and from the second conveyor 15 to the tablet carrier 16 by each carrier arm 26.

The tablet carrier 16 includes a carrier section 16a which reciprocates between the second conveyor 15 and the upper mold 2, and a cylindrical container section 16b which is attached to the carrier section 16a and accommodates the tablet 11. It consists of and. As shown in FIG. 4, for example, the insertion ports 16b ₁ of the four accommodating portions 16b formed corresponding to the four pots 10 (FIG. 2) have inner walls tapered outwardly, and the tablets 11 A large drop allowable area is secured, and the dropped tablet 11 is guided and positioned by the tapered surface. Tablet 1 in the storage section 16b
In order to hold No. 1, a support pin 27 penetrating in the accommodation portion 16b in the radial direction is provided on the opposite side of the input port 16b ₁ so as to be expandable and contractible. As a result, the tablet 11 is supported from below by the support pins 27 to prevent falling, and
When it is conveyed onto the pot 10 by the conveying portion 16a, the support pin 27 contracts, the supporting force is lost, and the support pin 27 falls into the pot 10. It should be noted that the number of accommodating portions 16b of the tablet carrier 16 is not limited to four, and the necessary number can be continued.

The air cleaning device 18 installed corresponding to the tablet carrier 16 has a suction port 18
The opening a is provided in the housing portion 16b. A vacuum pump 18b is attached so as to communicate with the suction port 18a, and is scattered by the tablet carrier 16 due to a drop impact from the second conveyor 15, and in particular, the tablet powder accumulated in the housing portion 16b is the vacuum pump 18b. The negative pressure is sucked and removed from the suction port 18a which is closely attached by the operation of (1) and is not brought into the pot 10. Although the brushing device 13 and the air cleaning device 18 are provided in the present embodiment, only one of them may be installed depending on the individual situation such as a relatively small amount of tablet powder adhered to the tablet 11 used. Good.

According to the carrying system C having such a structure, the tablet 11 is carried to the mold section M as follows.

First, the tablet 11 delivered from the parts feeder 12 is guided to the brushing device 13. Here, the cleaning powder of the brush 28 removes the tablet powder adhering to the tablet 11.

Next, the tablet 11 is transferred from the first conveyor 14 to the second conveyor 15 and then to the tablet carrier 16 by the carrier arm 26, and is dropped into the accommodating portion 16b of the tablet carrier 16. Then, when the tablet 11 is dropped into the housing portion 16b, the vacuum pump 1
8b is actuated to suck the tablet carrier 16 under negative pressure. As a result, the tablet powder newly generated due to the impact of dropping the tablet 11 or already accumulated in the tablet carrier 16 is sucked and removed from the suction port 18a.

Thereafter, the accommodating section 16b is moved by the conveying section 16a.
Is conveyed to a position right above the pot 10, where the support pin 2
7 shrinks and the tablet 11 drops into the pot 10.

As described above, according to the mold unit of the present embodiment, the tablet powder adhering to the tablet 11 and the tablet carrier 16 that carries the tablet 11 to the upper die 2 is swept away by the brush 28. It is removed and completely eliminated by the brushing device 13 using force and the air cleaning device 18 using negative pressure suction force by the vacuum pump 18b, and is not brought into the pot 10.

As a result, the solidified tablet powder does not drop onto the inner leads during molding, so that a short circuit defect due to the inner lead deformation due to the tablet powder can be prevented.

Further, since a lump of tablet powder is not taken in and molded, package cracks due to two resins having different heat histories can be prevented, and mold quality can be improved.

Further, since the tablet powder does not scatter, abrasion of the movable part of the mold part M due to the adhesion of the tablet powder is prevented, and the life of the device can be extended.

(Second Embodiment) FIG. 5 is an explanatory view showing an adhesive roller used in a mold unit according to another embodiment of the present invention.

The adhesive roller (third tablet powder removing means) 30 in the present embodiment removes the adhered tablet powder by using the adhesive force, and replaces the brushing device 13 in the first embodiment with the transfer. It was installed in system C.

The pressure-sensitive adhesive roller 30 has a cylindrical first roller 31 which rotates with its central axis set parallel to the central axis of the tablet 11 and the outer peripheral surface having adhesiveness contacting the outer peripheral surface of the tablet 11. Similarly, a state in which the central axis is set parallel to that of the tablet 11 and the adhesive tape 32 having an adhesive force equal to or higher than the adhesive force of the first roller 31 is wound and is in contact with the outer peripheral surface of the first roller 31. It is composed of a cylindrical second roller that rotates with the reel and a reel 34 that winds the adhesive tape 32.

According to this, the tablet powder adhering to the tablet 11 adheres to the first roller 31 and is removed. The tablet powder of the first roller 31 adheres to the adhesive tape 32 having a stronger adhesive force that is wound around the second roller 33 that rotates in contact with the first roller 31, and is wound on the reel 34. To be

Therefore, also in the mold unit according to the present embodiment, short-circuit defects, package cracks and wear of the movable parts of the device due to tablet powder are prevented. In addition, the first roller 31 having a function of transferring the tablet powder from the tablet 11 to the adhesive tape 32, and the second roller 33 to which the new adhesive tape 32 is constantly supplied by being wound around the reel 34.
Therefore, according to the adhesive roller 30 of the present embodiment, it is possible to endure long-term use.

(Third Embodiment) FIG. 6 is an explanatory view showing an adhesive roller used in a mold unit according to still another embodiment of the present invention.

The air blow device (fourth tablet powder removing means) 17 in this embodiment removes the adhered tablet powder by using the peeling force of the high pressure air (high pressure gas) 21. In place of the brushing device 13 in the above and the adhesive roller 30 in the second embodiment, the brushing device 13 is installed in the transport system C.

As shown in the figure, the air blower 17 has a chamber 20 forming a blow chamber 19 through which the tablet 11 passes, and, for example, two nozzles 22 for blowing high pressure air 21 to the tablet 11 in the blow chamber 19. There is. Therefore, the tablet powder adhered to the tablet 11 is removed by the high-pressure air 21 that is ejected when the tablet 11 is guided by the guide 23 and passes through the blow chamber 19.

To collect the removed tablet powder,
A dust collector 24 is installed below the chamber 20 and opens into the blow chamber 19.

It should be noted that instead of the high pressure air 21, for example N
_The tablet powder may be removed by using another gas such as an inert gas such as ₂ .

As described above, according to the mold unit of this embodiment, when the tablet 11 passes through the blow chamber 19, the adhered tablet powder is ejected from the high-pressure air 2
A stripping force of 1 removes it from the tablet 11.

As a result, the tablet powder is not brought into the pot 10, and it is possible to prevent short-circuit defects, package cracks, and abrasion of the movable parts of the device due to the tablet powder.

(Fourth Embodiment) FIG. 7 is an explanatory view showing a tablet carrier and an air cleaning device provided in a carrier system according to still another embodiment of the present invention.

For example, in the single-plunger type molding apparatus, since the pot 10 is formed only in one place, the tablets 11 are conveyed one by one instead of simultaneously. In the present embodiment, the tablet 11
Has a structure in which it is grasped by the arm 35a and conveyed, and when it reaches the upper mold 2, it is opened and put into the pot 10. However, in the tablet conveying body 35 which individually conveys the tablets 11 as described above, , Air cleaning device 18
Also, the tablet powder adhered to the tablet 11 and the tablet carrier 35 is removed with a size adapted to this.

(Fifth Embodiment) FIG. 8 is a sectional view showing a tablet which is another embodiment of the present invention.

The surface of the illustrated tablet 11 is coated with a coating material 36, which prevents the generation of tablet powder.
As the coating material 36, carnauba wax, Hoechst wax, or polyethylene that enhances the adhesive force with the leads can be used.

By coating the surface of the tablet 11 in this way to prevent the generation of tablet powder, the tablet 11 can be put into the pot of the mold as it is without any treatment for removing the tablet powder. ,
Prevents short circuit of inner leads, package cracks, and abrasion of moving parts of the device.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments and various modifications can be made without departing from the scope of the invention. It goes without saying that it is possible.

For example, in the above-mentioned embodiment, the brushing device 13, the air cleaning device 18, the adhesive roller 30 and the air blow device 17 are used as the first to fourth tablet powder removing means. It is possible to install any one of these four tablet powder removing means alone or to install two or three of them together.

[0058]

The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described as follows.

(1) That is, according to the molding technique of the present invention, the tablet powder adhered to the tablet or the tablet carrier is previously removed before being dropped into the pot, or the tablet is coated with a coating material. Since the powder itself is not generated, the tablet powder is not brought into the molding device.

(2) As a result, the solidified tablet powder does not fall onto the inner leads during molding, so that it is possible to prevent short-circuit defects due to inner lead deformation due to the tablet powder.

(3) Further, according to the above (1), since a lump of tablet powder is not taken in and molded, package cracks due to two resins having different heat histories can be prevented, and mold quality is improved. Can be achieved.

(4) In addition, since the tablet powder does not scatter due to the above (1), abrasion of the movable part of the molding device due to the adhesion of the tablet powder is prevented, and the life of the device is prolonged. It will be possible.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a mold section of a mold unit according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a transport system for transporting a tablet to a mold section in FIG. 1;

FIG. 3 is an explanatory view showing a part of the transport system of FIG. 2 in an enlarged manner.

FIG. 4 is an explanatory view showing another part of the transport system of FIG. 2 in an enlarged manner.

FIG. 5 is an explanatory diagram showing an adhesive roller used in a mold unit according to Embodiment 2 of the present invention.

FIG. 6 is an explanatory diagram showing an adhesive roller used in a mold unit according to Embodiment 3 of the present invention.

FIG. 7 is an explanatory diagram showing a tablet carrier and an air cleaning device provided in a carrier system according to a fourth embodiment of the present invention.

FIG. 8 is a sectional view showing a tablet according to Embodiment 5 of the present invention.

[Explanation of symbols]

1 Lower Mold 2 Upper Mold 3 Base 4 Movable Plate 5 Guide 6 Heater 7 Fixed Plate 8 Hydraulic Cylinder 9 Plunger 10 Pot 11 Tablet 12 Parts Feeder 13 Brushing Device (First Tablet Powder Removing Means) 14 First Conveyor 15 2nd conveyer 16 tablet carrier 16a carrier part 16b accommodating part 16b ₁ input port 17 air blow device (4th tablet powder removing means) 18 air cleaning device (2nd tablet powder removing means) 18a suction port 18b vacuum pump 19 Blow chamber 20 Chamber 21 High pressure air (high pressure gas) 22 Nozzle 23 Guide 24 Dust collector 26 Transfer arm 27 Support pin 28 Brush 28a Roller 28b Brush part 29 Brush cleaner 30 Adhesive roller (third tablet powder removing means) 31 First roller 32 Adhesive tape 33 Second roller 34 Reel 35 Tablet carrier 35a Arm 36 Coating material C Conveying system M Mold part (molding device)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Bunji Kuratomi 5-20-1 Kamimizuhonmachi, Kodaira-shi, Tokyo Inside the Semiconductor Division, Hitachi, Ltd. (72) Inventor Fukumi Shimizu 3-chome, Fujihashi, Ome-shi, Tokyo 3-2 Hitachi Tokyo Electronics Co., Ltd. (72) Inventor Inoue Niigata Yonebashi, Yonebashi, Yonezawa, Yamagata Prefecture 3274 3274 Hitachi Yonezawa Electronics Co., Ltd. 3274 Hitachi Yonezawa Electronics Co., Ltd. in East 3

Claims (6)

[Claims] 1. A molding method, characterized in that tablet powder adhering to the surface of the tablet is removed before the tablet is put into a pot of a molding apparatus for semiconductor molding. 2. The molding method according to claim 1, wherein
The molding method, wherein the tablet powder is removed by using at least one of a stripping force by high-pressure gas jetting, a brush sweeping force, an adhesive force of an adhesive material, and a negative pressure suction force. 3. A transport system for transporting tablets to a pot of a molding apparatus for semiconductor molding, wherein at least one tablet powder removing means among the first to fourth tablet powder removing means described below is installed. Mold unit that is characterized by. (1) First tablet powder removing means for sweeping tablet powder adhering to the surface of the tablet with a brush. (2) Second tablet powder removing means for negatively sucking the tablet powder attached to the tablet and the tablet carrier that puts the tablet in the pot. (3) The central axis is set parallel to the central axis of the tablet, and the tablet powder is removed from the tablet by rotating around the central axis with the outer peripheral surface having adhesiveness in contact with the outer peripheral surface of the tablet. A cylindrical third tablet powder removing means. (4) From a blow chamber through which the tablet passes, a nozzle that ejects high-pressure gas to the tablet in the blow chamber to remove tablet powder attached to its surface, and a dust collector that sucks the removed tablet powder. The fourth tablet powder removing means. 4. The mold unit according to claim 3, wherein the first tablet powder removing means is provided with a cleaner for sucking and removing the tablet powder attached to the brush. 5. A tablet which is formed by compressing a thermosetting resin into a predetermined shape, plasticizes it and press-fits it into the cavity of a mold to mold a semiconductor chip, and the surface of this tablet is coated with a coating material. A tablet that is characterized by being. 6. The tablet according to claim 5, wherein the coating material is carnauba wax, Hoechst wax or polyethylene.