JP3028997B2 - How to attach film to lead frame - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of attaching an insulating or conductive adhesive film to a lead frame and attaching the film to a lead frame. It relates to a film sticking method.

[0002]

2. Description of the Related Art A COL (Chip O
Adhesives (thermoplastic and thermosetting adhesives, etc.) are previously applied to one or both sides of a high heat-resistant polyimide film for mounting semiconductor chips on lead frames with n Lead) or LOC (Lead on Chip) structures. There is a film that has been put into practical use as a prefabricated lead frame by attaching a film with an adhesive.

[0003] In such a lead frame, when attaching a film with an adhesive, for example, a film attaching device as shown in FIG. 4 is used. The film sticking apparatus includes a punching punch 1 that cooperates with a die 2 and punches and shears a film 7 into a predetermined shape.
A heater block 5 for cooperating with the punch 1 descending to the bottom dead center to pinch the film 7 and the lead frame 6 by the pressing force of the punch 1 and heat the lead frame 6 to a predetermined temperature, and moving the punch 1 up and down. And a pilot pin 11 which is inserted into the pilot hole 10 of the lead frame 6 when the punch 1 is lowered to adjust the transport position of the lead frame 6, that is, the film sticking position.

In this film sticking apparatus, first, as shown in FIG. 5, a punch 1 is lowered to punch a film 7 into a predetermined shape, and a pilot pin 11 is inserted into a pilot hole 10 of a lead frame 6.
The lead frame 6 is positioned, and then, as shown in FIG. 6, the punched film 7 is pressed and sandwiched together with the lead frame 6 therebelow into the heater block 5 so that the film 7 is positioned at a predetermined position on the lead frame 6.
Can be attached by thermocompression bonding.

When the film 7 is punched, the film 7 punched by the punch 1 generally has a width of 20 to 30 μm from the front end surface of the punch 1 (or the opening area of the die 2) as shown in FIG. As shown in FIG. 8, when the punch 1 projects from the die 2, the film 7 is displaced in the horizontal direction and cannot be stuck to a predetermined position of the lead frame 6. For this reason, the film 7 punched by the plurality of suction holes (outer diameter of about 0.5 mm) 4 provided at the tip of the punch 1 is suction-fixed to reduce the lateral displacement of the film 7.

However, even if the film is adhered to the lead frame by adsorbing and fixing the film with the adsorbing hole as described above,
It only reduces the deviation of the film, and it is difficult to satisfy the ± 0.1 mm film sticking position accuracy required by the user. Also, since a film is stuck at the tip of the punch, if there is a hole there is no pressure applied to this hole when the film is stuck. Because of this, not only that part becomes unbonded, but also because there is a non-uniform part of the pressure in the adhesive layer, it is over-pressed and peeled off from the adhesive layer of the film,
That is, the rapidly softened adhesive flows in the adhesive layer inside the hole at the time of bonding, and hardens during the flow to form a vacuum space in this portion. This excessive push-off peeling may remain even after the package is sealed with a resin, and if moisture is absorbed into the voids, it will lead to package cracks and must be prevented during manufacturing.

Therefore, as a countermeasure against this, a method of re-pressing the hole portion on the tip end face of the punched film on the film is considered.

[0008]

However, according to the conventional method of affixing a film to a lead frame, the film is suction-fixed by a suction hole provided on the tip end surface of a punching punch. It is necessary to crimp the hole part of the punch tip surface again, which increases the man-hour,
There is a disadvantage that the workability is reduced and the cost is increased.

Further, if the gap between the heater block and the die is reduced as much as possible, the displacement of the film can be reduced as much as possible. However, in this case, excessive heat is applied to the mold and the lead frame, and the pattern of the lead frame is reduced. If it is deformed due to thermal expansion and a film is attached to it, the film will be displaced and attached when returning to a normal temperature state.

Accordingly, it is an object of the present invention to provide a method of attaching a film to a lead frame, which can greatly improve the accuracy of the position at which the film is attached without performing complicated operations.

[0011]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention has been made in consideration of the above-mentioned problems, and in order to greatly improve the accuracy of the film sticking position without performing a complicated operation, a pad provided on a lead frame has been proposed.
By inserting a pilot pin into the pilot hole
When the adhesive film is adhered to the lead frame with the lead frame positioned , the lead frame has a minute distance between the die and 1/3 to 1.3 times the thickness of the adhesive film. was located, there is provided a film sticking method to the lead frame.

The lead frame is arranged at a minute distance by an actuator such as a cylinder mechanism for raising and lowering a heater .

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for attaching a film to a lead frame according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an apparatus for attaching a film to a lead frame applied to the present invention. In this figure, the same parts as those in FIG. 4 are denoted by the same reference numerals, and a duplicate description will be omitted.

The film sticking device for the lead frame has an actuator 9 such as an air cylinder for moving the heater block 5 up and down.

The actuator 9 is used to attach the film 7 to the lead frame 6, that is,
Immediately before lowering, as shown in FIG. 2, the heater block 5 is raised, and the lead frame 6 located thereon is arranged at a small distance C below the die 2. Here, the distance C is 1 of the thickness of the film 7.
/ 3 to 1 times (actually, the punched film 7 bends downward, so that it can be up to about 1.3 times). If the distance C is within this range, the pilot pin 11 is connected to the pilot hole. 10 can be easily inserted (the lead frame moves following the tapered shape of the tip of the pilot pin 11), and the accuracy of the film sticking position to the lead frame 6 can be improved.

The reason why the distance C between the die 2 and the lead frame 6 is in the range of 1/3 to 1.3 times the thickness of the film 7 is that the distance between the die 2 and the lead frame 6 is made as small as possible. Write but are enhanced attaching position accuracy, by setting the distance C of the film thickness to 1/3 times or less, the distance C is
Because it is too small , lead frame with pilot pin 11
When you regulate the location, movement difficulty Ku fine lead frame 6
Adjustment becomes difficult, forcibly insert the pilot pin
When not only damage the pilot holes 10, will be kicking sticking a film 7 to a position shifted, also setting the distance C over 1.3 times the film thickness, the die 2
This is because the film 7 jumps out from the horizontal direction and cannot be attached to a predetermined position.

Hereinafter, a method for attaching a film to a lead frame according to the present invention will be described. First, prior to lowering of the punch 1, as shown in FIG. 2, the heater block 5 is raised by the actuator 9, thereby lifting the lead frame 6 and disposing the lead frame 6 below the die 2 with a distance C. . When the punch 1 is lowered, the punch 1 cooperates with the die 2 to punch and shear the film 7 into a predetermined shape, and then, as shown in FIG. The film 7 is adhered to a predetermined position of the lead frame 6 by thermocompression by pressing the lead frame 6 arranged at a distance C to the heater block 5 raised by the actuator 9 and sandwiching the same.

When the lead frame 6 is disposed at a distance C below the die 2 and the film 7 is attached at that position level, the position where the punch 1 is attached to the lead frame 6 is determined using the die 2 as a guide. Therefore, the accuracy of the position where the film 7 is attached to the lead frame 6 can be increased. Specifically, the standard deviation of the deviation can be reduced to 0.015 or less, and ± 0.075 can be secured even when mass production is performed (± 4σ). Thus, the positional accuracy can be greatly improved.

Further, since the heater block 5 is in a standby state away from the die and is heated by contacting with the lead frame 6 only when necessary, heat dissipation through the die 2 is reduced, and the punch It is possible to reduce the influence of heat on the die 1 and the die 2 and to prevent the displacement of the bonding position due to the thermal expansion of the inner pattern of the lead frame 6. Furthermore, since the heat source is used only at the time of sticking, it is effective for energy saving.

Further, since it is not necessary to provide a plurality of suction holes on the end surface of the punch 1, it is not necessary to perform complicated processing on the apparatus, and it is not necessary to re-press the holes. Therefore, an increase in man-hours can be suppressed, and workability can be improved and cost can be reduced.

The adhesive applied to the film 7 is a thermoplastic adhesive, and requires a predetermined pressure, temperature and time for sound bonding. In the present invention, since the heater block 5 is moved up and down by the actuator 9, the bonding state can be controlled by controlling the pressure and the operation time of the actuator 9. Further, without being limited to this, the operation of the heater block 5 is controlled by a cam,
The same effect can be obtained by controlling the bottom dead center using a mechanism such as a link.

The present invention is not limited to affixing a film to a lead frame having a LOC / COL structure.
The present invention can also be applied to attaching a lead fixing tape.

[0024]

As described in the foregoing, according to the film joining method of the lead frame of the present invention, the lead frame
Insert the pilot pin into the pilot hole provided in the
When attaching the adhesive film to the lead frame with the lead frame positioned by inserting it, the lead frame has a specific minute distance between the die to prevent the adhesive film from shifting. To be located
It is possible to greatly improve the accuracy of the film sticking position without performing a complicated operation.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a film sticking apparatus applied to the present invention.

FIG. 2 is a sectional view showing one embodiment of the present invention.

FIG. 3 is a sectional view showing one embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a film sticking apparatus applied to a conventional film sticking method.

FIG. 5 is a sectional view showing a conventional film sticking method.

FIG. 6 is a sectional view showing a conventional film sticking method.

FIG. 7 is a cross-sectional view showing a state at the time of punching a film in a conventional film sticking method.

FIG. 8 is a cross-sectional view showing a state after punching a film in a conventional film sticking method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Punching punch 2 Die 3 Stripper 4 Suction hole 5 Heater block 6 Lead frame 7 Film 9 Actuator 10 Pilot hole 11 Pilot pin

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Satoshi Sasaki 3550 Kida Yomachi, Tsuchiura-shi, Ibaraki Hitachi Systems, Ltd. System Materials Research Laboratories (72) Inventor Hiroyuki Takasaka 3-1-1 Sukekawacho, Hitachi-shi, Ibaraki No. 1 Inside the wire plant of Hitachi Cable Co., Ltd. (56) References JP-A-4-196576 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 23/50

Claims (2)

(57) [Claims] 1. An insulating or conductive adhesive film located on a die is punched into a predetermined shape by a punch, and is adhered to a predetermined position of a lead frame on a heater located below the die. In the method of affixing a film to a lead frame, the pilot hole provided in the lead frame is
Inserting the lead pin into the lead frame
When attaching the adhesive film to the lead frame in a state where is positioned , the lead frame is placed between the die and a minute distance of 1/3 to 1.3 times the thickness of the adhesive film. A method for affixing a film to a lead frame, characterized in that the film is held and positioned. 2. The method according to claim 1, wherein the lead frame is disposed at the small distance by an actuator such as a cylinder mechanism for raising and lowering the heater.