JPH06326238A - Film applying method - Google Patents

Abstract

PURPOSE:To realize high speed application of film by allowing local cooling, i.e., the cooling only at the unnecessarily high temperature parts of a metal mold. CONSTITUTION:A film 8 is punched by means of a punching metal mold comprising a punch 7, a die 2 and a stripper 3. The punched film 8 is then transferred to a predetermined position where the film 8 is applied to a lead frame 1 heated by a heating means. In this regard, high pressure air is fed through a cold air hole 9 made through the punch 7 in the vicinity of film applying part in order to apply the film 8 while locally cooling the metal mold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for attaching a film to a lead frame, and more particularly to a method for attaching a film to a lead frame with high quality.

[0002]

2. Description of the Related Art With the development of high-density packaging technology for integrated circuits, the number of input / output pins corresponding to the chip area is increased, the number of chips mounted on the board is reduced, and the board is downsized. Has been implemented. A conventional lead type, surface mount type, or the like can be considered as a method of mounting the substrate. In consideration of the increase in the number of input / output pins corresponding to the chip area and the mounting of the board, various types of high reliability and high quality lead frames have been developed in recent years.

In a lead frame on which an IC or LSI is mounted, a film is conventionally punched or cut into a strip shape and attached to the lead tip in order to prevent a step or shift of the lead tip, or LOC.
In the (Lead On Chip) structure and the like, a film is often attached to the lead frame in order to attach the lead and the chip.

As a method for sticking such a film, a film sticking apparatus as shown in FIG. 4 is used.
A method is used in which the film 8 is cut or punched into a predetermined shape with a mold and then attached to a lead frame 1 which is a material to be attached and which is placed immediately below. In the film sticking apparatus shown in FIG. 4, the die is a punch 7, a die 2,
It is composed of a punch guide 3 or a stripper, a heater 4 is arranged at the lower part of the die, and the lead frame 1 which is positioned in advance on the heater 4 is mounted.

A conventional film sticking method using such a film sticking apparatus is shown in FIGS. 5 (a), 5 (b) and 5 (c). In the conventional film sticking method, as shown in FIG. 5A, the punching film 8 is fed in a tape shape between the punch guide 3 and the die 2,
The lead frame 1 is set on the lower surface of the die, while the lead frame 1 is set on the lower surface of the die, and then the shank 6 of the die is pushed, so that the punch 7 is moved to the film 8 as shown in FIG.
5 is cut or punched into a predetermined shape, and the heater 4 heated to the lead frame 1 waiting on the lower surface of the die 2 as shown in FIG.
It is designed to be attached via heating).

Since high dimensional accuracy is required for the die heated by the heater 4, that is, the punch 7, the die 2 and the punch guide 3, if these are overheated, the punch 7 and the die 2 will be damaged. However, since the clearance between the punch 7 and the punch guide 3 changes, normal punching cannot be performed. For this reason, in the conventional film sticking apparatus as shown in FIG. 4, as an example of measures against overheating, a method of providing a water cooling pipe 11 in the mold body and cooling the entire mold with water is mainly adopted. . In this water cooling method, cold water is circulated through a circulating water cooling pipe line 11 in the mold to cool the mold and prevent overheating of the punch 7, the die 2, the punch guide 3, and the like.

[0007]

However, the water cooling method which is the conventional measure against overheating has the following problems. 1. Since this method is a water-cooling method, the circulation of the circulating water passage 11 is complicated when a cold water circulating water passage network is provided in consideration of heat conduction in the overheated portion in the mold. 2. The circulating water passage 11 in the mold is corroded by the cold water circulation in the mold, which may cause water leakage or deterioration of cleanliness.

3. When the cold water temperature is low, the surface of the mold is condensed and the sticking film 8 absorbs moisture. (In general, a sticking film is often made of a material having a high hygroscopic property, and when it absorbs moisture, the sticking property, the die-bonding property, or the property after assembly may be significantly deteriorated.) Expensive equipment and troublesome maintenance such as a cold water circulation unit for circulating cold water in the circulating water passage 11 in the mold are required. 5. Since the punch 7 is small, it is impossible to process the cold water circulation passage 11 at the punch tip portion, and it is not possible to cool only the punch tip portion, which is a high temperature portion. Therefore, when the sticking speed is increased, the temperature at the tip of the punch rises, and the punch 3 adheres to the adhesive layer of the film 8 in contact with the punch 3.

An object of the present invention is to solve the above-mentioned problems of the prior art, to cool only an unnecessary high temperature portion of a mold, and to perform high speed bonding by local cooling. There is a way to provide.

[0010]

In order to achieve the above object, the present invention punches a film using a film punching die composed of a punch, a die and a stripper, or a punch guide, and punches at the tip of the punch. When the removed film is conveyed to a predetermined position and the film is attached to the lead frame heated by the heating means, high-pressure gas is supplied to the cold air holes provided near the film attaching portion of the punch for attaching the film. It is intended to provide a film sticking method, which is characterized in that the film is stuck by locally cooling in a sink. Here, it is preferable that the cold air holes, that is, the cold air holes at the tip of the punch are opened in the vicinity of the film attaching portion.

[0011]

According to the film sticking method of the present invention, cold air holes are provided in the vicinity of the punch tip, which is the entrance of heat to the die, that is, in the vicinity of the film sticking portion, and high pressure gas (air (Or nitrogen etc.)
It enables local cooling of the mold and speeds up film attachment.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The film sticking method according to the present invention will be described below in detail with reference to the preferred embodiments shown in the accompanying drawings.

1 (a), 1 (b) and 1 (c) show the punching and sticking process of the film sticking method of the present invention, using the essential parts of one embodiment of a film sticking apparatus for carrying out this process. FIG. 4 is a partial cross-sectional view showing the state before punching, the state of local cooling after punching, and the state during sticking, respectively. Here, the film sticking apparatus used in the present invention is the same as the film sticking apparatus shown in FIG. 4 except that the punch 7 is provided with the cold air holes 9, so that the tip of the punch 7, the die 2, the punch. Only the main part including the guide 3 and a part of the heater 4 and the like are shown, and the other drawings and detailed description are omitted.

As shown in FIG. 1 (a), the film sticking method of the present invention uses a film sticking apparatus in which a cold air hole (cold air passage) 9 is provided at the tip of the punch 7, and the film is compressed from the punch holder 5 side. It is characterized in that only the tip of the punch is locally cooled by flowing the generated gas.

The film sticking apparatus includes a positioning mechanism (not shown) for setting the lead frame 1 at a predetermined position, a heater 4 for heating the lead frame 1, and a feeding mechanism for feeding the film 8 to a predetermined cutout position. (Not shown), a punching mechanism that cuts the film 8 into a predetermined shape, a die 2, a punch guide 3, a punch holder 5, a shank 6, and the like, and the cut-out film 8 is conveyed to the vicinity of the lead frame 1. A transport mechanism including a punch 7, a punch guide 3, a shank 6, and the like, a pressing mechanism including the punch 7 and the shank 6 that press the transported film 8 against the heated lead frame 1 at a predetermined position, and a tip of the punch 7. And a cooling mechanism including a cold air hole 9 for locally cooling the.

In the method of the present invention, as shown in FIG. 1A, when the lead frame 1 is supplied under the die 2 of the film sticking apparatus, the lead frame is driven by a positioning mechanism (not shown) of the film sticking apparatus. 1 is aligned and installed at a predetermined position. Next, as shown in FIG. 1B, the adhesive-attached film 8 sent between the punch guide 3 and the die 2 is used as a die in a punching die composed of the punch 7 and the die 2. By pressing the shank 6 which drives the punch 7, the punch 7 punches the punch 7 into a predetermined shape. Here, when the open end of the cold air hole 9 provided in the punch 7 comes into the gap between the die 2 and the punch guide 3 and is opened, a gas compressed to a high pressure from the side of the punch holder 5, for example, Air, nitrogen, etc. are cold air holes 9
And is discharged from its open end, so that only the tip of the punch 7 is locally cooled.

As shown in FIG. 1 (c), the punched film 8 is attached to the tip of the punch 7 by an attaching means (not shown), and is pressed onto the lower surface of the die 2 by pressing the shank 6 which constitutes the transport mechanism. Lead frame 1 waiting
It is transported to the vicinity of (immediately above). Then, the transported film 8 is further pressed by the shank 6 against the lead frame 1 heated to a predetermined temperature (for example, about 400 ° C. in the thermoplastic film 8) by the heater 4,
Alternatively, while the lead frame 1 is placed on the heater 4, the heater 4 is lifted by using a moving mechanism (not shown) to be pressed and attached. Here, the lead frame 1 is heated to a temperature corresponding to the adhesive-attached film 8 by the heater 4, but since the tip of the punch 7 is locally cooled by the cold air holes 9, it is not overheated and the film 8 is not heated. Does not adhere to the tip of the punch 7.

Further, in the present invention, as shown in FIG. 2, the punch guide 3 is provided with the drain groove 10, and the foreign matter on the film 8 or the punching burr of the film 8 can be blown off and removed. May be

FIG. 3 shows an example of the relationship between the bonding conditions, that is, the bonding time and the bonding temperature when a film with a thermoplastic adhesive is used. Although the sticking time is shortened by increasing the sticking temperature, when the sticking temperature is further raised, the tip temperature of the punch 7 is increased by the method using only the circulating cold water conduit 11 of the conventional punch holder 5 shown in FIG. Rises above the film bonding temperature and the film 8 adheres to the punch 7. Therefore, it is effective to directly cool the vicinity of the tip of the punch 7, but in the present invention, a cold air passage (cold air hole 9) extending to the vicinity of the tip of the punch 7 is provided, which is preferable. Since this cold air passage is opened near the tip of the punch 7, only the tip of the punch 7 can be directly and effectively cooled. Therefore, in the present invention, there is no problem of adhesion between the adhesive layer of the film 8 and the punch 7, and high quality attachment of the film 8 to the lead frame 1 can always be performed in the appropriate adhesion region.

The gas used to flow into the cold air holes 9 in the method of the present invention is the film 8, the adhesive of the film 8, the lead frame 1 and various members constituting the apparatus, such as the punch 7, the die 2 and the punch. Any type of cold air can be used as long as it can cool the tip of the punch 7 as long as it does not deteriorate or deteriorate the metal mold of the guide 3 or the like. For example, as this gas, air or nitrogen,
Although an inert gas such as argon can be used, it is preferable to use an inert gas because the use of the inert gas can simultaneously prevent oxidation due to heating of the lead frame 1. Further, the temperature of the gas is a temperature at which the film 8 is adhered to the punch 7 at room temperature or at a low temperature as long as the tip of the punch 7 can be cooled to a temperature at which the film 8 is not adhered to the punch 7. The following temperature or any temperature may be used.

In the example shown in FIGS. 1A to 1C, a cold air passage (cold air hole 9) provided in the punch 7 and extending to the vicinity of the tip of the punch 7 is opened near the tip of the punch 7. However, the present invention is not limited to this, and the cold air passage may or may not be opened at a portion other than the tip portion of the punch 7 as long as cold air can cool the tip portion of the punch 7. . Further, one cold air passage may be provided in the punch 7 as shown in the drawing, or a plurality of cold air passages may be provided, and further, cold air may be circulated in the punch 7.

In the above embodiment, only the cold air holes 9 are provided in the punch 7, but the present invention is not limited to this, and when the punch 7 is large and a circulating cold water pipe can be provided, Water cooling may be performed. If sufficient local cooling is possible only with water cooling, only the circulating cold water pipeline may be provided.

[0023]

As described in detail above, according to the film sticking method of the present invention, the punch tip, which is a heat inlet, is cooled, so that the mold temperature can be kept constant (hence, the metal mold temperature). (The mold clearance can be kept constant), and the film can be punched and the film can be attached to the lead frame with high quality at an appropriate high accuracy. Further, according to the method of the present invention, only the portion requiring cooling, that is, only the high temperature portion of the tip of the punch is locally cooled, so that the attachment temperature can be increased and high-speed attachment can be achieved. . Furthermore, according to the method of the present invention, high temperature oxidation of the lead frame can be prevented by using an inert gas such as nitrogen gas as the cooling gas. Furthermore, according to the method of the present invention, the cold air holes are not closed, and even if the cold gas leaks, the cooling effect can be exerted, so that it can be applied to a complicated fine portion, and its processing. Will be easier.

[Brief description of drawings]

1 (a), (b) and (c) are, respectively,
It is a fragmentary sectional view showing the state of each process before punching of the example of the film pasting device which carries out the film pasting method concerning the present invention, local cooling after punching, and during pasting.

FIG. 2 is a partial cross-sectional view showing another embodiment of the film sticking apparatus for carrying out the film sticking method according to the present invention.

FIG. 3 is a graph showing an example of film sticking conditions used in the film sticking method 2 of the present invention.

FIG. 4 is a partial cross-sectional view showing a mold structure of a film sticking apparatus according to a conventional technique.

5 (a), (b) and (c) are respectively,
It is a partial cross-sectional view which shows the state of each process before punching, after punching, and during sticking of the film sticking apparatus which implements the conventional film sticking method.

[Explanation of symbols]

 1 Lead Frame 2 Die 3 Punch Guide 4 Heater 5 Punch Holder 6 Shank 7 Punch 8 Film 9 Cold Air Vent 10 Drain Groove 11 Cold Water Pipeline

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hirotoshi Endo 3550, Kidayo-cho, Tsuchiura-shi, Ibaraki Prefecture Hitachi Cable Ltd. System Materials Laboratory (72) Inventor Hiroshi Sugimoto 3550, Kida-yocho, Tsuchiura-shi, Ibaraki Hitachi Cable Co., Ltd. System Materials Research Center

Claims (2)

[Claims] 1. A film punching die comprising a punch, a die and a stripper or a punch guide is used to punch a film, and the punched film is conveyed to a predetermined position and heated by a heating means. When pasting the film on the lead frame, high-pressure gas is caused to flow through the cold air holes provided in the vicinity of the film pasting part of the punch for pasting the film, and the film is pasted by local cooling. How to attach. 2. The film sticking method according to claim 1, wherein the cold air holes are opened near the film sticking portion.