JP2989700B2 - Semiconductor resin deburring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for removing a resin flash from a resin-sealed semiconductor lead frame by a press die having an upper die and a lower die. .

[0002]

2. Description of the Related Art In general, in molding a resin-encapsulated semiconductor, an apparatus is used which automatically performs everything from supply of a lead frame and a resin tablet to resin encapsulation, and furthermore, to housing thereof. .

As shown in FIGS. 5 and 6, an outer lead 3 is formed in a resin-encapsulated semiconductor formed by the above-described apparatus so as to connect between a resin molded body 1 and a lead frame 2. The resin burrs 4 are attached to both sides of the outer lead 3, respectively. This resin burr 4 needs to be removed because a solder defect occurs in a subsequent soldering step.

Conventionally, as shown in FIG. 7, a lower mold 5 and an upper mold 6 of a press die are used to remove the resin flash 4.
And the resin beam 4 is released. That is, a receiving portion 5a for receiving the lead frame 2 is formed in the lower die 5, and a V-shaped concave portion 6a is formed in the upper die 6, so that the upper die 6 is disposed on the lead frame 2 disposed in the receiving portion 5a. By lowering 6, the resin burr 4 is beveled in the recess 6a. Thereby, the resin flash 4 is separated (see FIG. 8).

Here, the thickness of the lead frame 2 is about 0.1 to 0.2 mm, and the amount of crushing of the lead frame for releasing the flash is a very small value of about 0.03 to 0.07 mm. In addition, the crushing amount is changed depending on the material of the lead frame 2 and the resin. Further, the allowable range of the variation of the crushing amount is as small as 0.02 mm or less.

[0006]

By the way, as a press using the above-mentioned press die, a press such as an air press or a hydraulic press is known. This type of press has the advantages that the variation in the amount of crushing can be controlled within the allowable range of 0.02 mm and that even if the thickness of the lead frame 2 changes, it can cope with the change.

[0007] On the other hand, however, the vertical speed of the upper die 6 is low, which is unsuitable for mass production, and when there is a gate residue at the time of sealing, the pressing force concentrates on the gate portion, and the separation of the resin flash is effective. There was a problem that was not done.

[0008] As a press other than the above, there is a so-called crank press. FIG. 9 shows its basic configuration. The rotation of the motor 7 is transmitted to the crank 9 by the crank shaft 8 via the timing belt 7a, and the upper die 6 moves up and down via the upper die holder 10 connected to the lower end of the crank 9. In the case of this crank press machine, the upper die 6 has a fast moving up and down speed, which is suitable for mass production.

However, in this case, it is difficult to set the amount of engagement between the upper die 6 and the lower die 5, and the lead frame 2
However, there is a disadvantage that when the thickness dimension is changed, it cannot be dealt with. In addition, since the bottom dead center of the upper die 6 is determined, if there is a remaining gate as described above, the gate will be caught at the bottom dead center, the press machine will not operate, and the die may be damaged. there were.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to change the amount of crushing when the thickness of a lead frame is changed, and to detect foreign matter caught in a gate or the like. An object of the present invention is to provide a semiconductor resin flash removing device which can prevent a mold from being damaged.

[0011]

According to the present invention, there is provided a semiconductor resin burr removing apparatus for removing a resin burr adhered to a resin-encapsulated semiconductor lead frame by using a press die having an upper die and a lower die. A servomotor for moving the upper die up and down, a position control means for calculating a proper lower limit position of the upper die and controlling the servomotor to be at the proper lower limit position; and Torque detecting means for detecting the load torque of the motor, determining means for determining the presence or absence of a press abnormality based on the torque detected by the torque detecting means, and stopping the operation of the servomotor when the determining means determines a press abnormality. And operation control means.

[0012]

Since a servomotor is used as a drive source of the upper die and position control means for calculating an appropriate lower limit position of the upper die and controlling the lower limit position thereof is provided, the lower limit position of the lower die of the upper die is provided. It is easy to change the setting, and the press torque is determined by detecting the load torque applied to the servomotor. Therefore, it is possible to detect the foreign matter caught in the gate or the like.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 2 schematically shows the entire configuration. The lower die 11 is provided on a lower die holder 12, and the upper die 13 is provided on an upper die holder 15 that moves a guide bar 14 up and down. A ball screw 16 is fixed to the upper part of the upper die holder 15.

On the other hand, the rotation of a servomotor 17 as a drive source provided on a frame (not shown) is transmitted to a screw rod 19 via a timing belt 18. The screw rod 19 is screwed into the ball screw 16 so that the upper die holder 15 and thus the upper die 13 move up and down in accordance with the rotation direction of the screw rod 19. As shown in FIG. 4, a receiving portion 11a for receiving the outer lead 3 of the lead frame 2 is formed in the lower die 11, and a V-shaped concave portion 13a is formed in the upper die 13.

FIG. 1 shows a control system. The controller 20 controls the driving of the servomotor 17, and various data for releasing the resin flash are input to the controller 20 from the data input unit 20a. The controller 20 gives commands corresponding to various data to the servo amplifier 21 and the servo amplifier 2
1 drives the servomotor 17 according to this command.

A pulse generator 22 is provided on the rotation axis of the servo motor 17, and feeds back the rotation amount of the servo motor 17 to the servo amplifier 21 and the controller 20. The servo amplifier 21 also functions as torque detecting means, and the torque detection data is given to the controller 20.

In FIG. 4, the thickness dimension of the lead frame 2 is indicated by the symbol d, and the crush amount (crush stroke) is indicated by the symbol S. Data for setting the crush amount S is input to the controller 20. When the entire stroke of the upper die 14 to the lower die 11 is H ₀ and the allowable minimum crushing amount for the lead frame 2 is d ₀ , the lower die 1
Stroke _{H 1} of the upper die 14 comes into contact with the lead frame 2 on 1 (collapsed starting position), _H 1 _{= H} 0 - represented by _(d-d 0).

The upper mold 1 in consideration of the crush amount S
4-stroke to be controlled in the _{H D N} (proper lower limit position)
Becomes H _DN = H ₁ + S. The above-described calculation is executed by the controller 20, that is, it functions as a position control unit. Also, this controller 20
Has a torque determination reference value for abnormality determination in advance as data, and also functions as a determination means for determining press abnormality. In addition, the servo motor 1 according to the determination result.
7 also functions as operation control means for stopping the operation.

The above-described torque determination reference value is determined based on the torque characteristics in FIG. In FIG. 3,
The load torque characteristic when there is no load abnormality when the upper die 13 descends is shown. As can be seen, from the upper limit position of the upper mold 13 to crush the start position H ₁ is low torque, descending stroke crush start position H of the upper mold 13
_When it reaches ₁ , the torque rises sharply and the proper lower limit position H
_It gradually rises to _DN . Thus, for example, to reach the crush start position H _1, if the torque Te exceeds the normal torque Tj, will be able to determine the occurrence of abnormal torque That press abnormal, the controller 20 in advance the torque Te as a torque determination reference value Have.

In the above configuration, when the controller 20 is given a resin flash removal start command, the controller 20
Outputs a start command to the servo amplifier 21, and the servo amplifier 21 drives the servo motor 17 to rotate in a predetermined direction.
By the rotation of the servomotor 17, the upper die 13 is lowered. Along with the start of the drive, the controller 20 starts comparing the torque detection data provided from the servo amplifier 21 with the above-described torque determination reference value Te. Then, the upper die 13, before reaching the crush start position H _1, when the torque detection data remains less torque determination reference value Te is directly, lowers the upper die 13 to the proper lower limit position H _DN, resin Release the beam 4. Then, it is raised to the upper limit position.

Meanwhile, the upper die 13, before reaching the crush start position H _1, the torque detection data torque determination reference value T
If the value exceeds e, it is determined that the gate or the like remaining on the lead frame 2 is jammed (press abnormality), and the controller 20 outputs a stop command to the servo amplifier 21 so as to stop driving the servo motor 17. . As a result, the upper mold 13 and the lower mold 11 are not damaged.

Further, when resin burrs are removed from lead frames 2 having different thicknesses d, data relating to the thickness d is given to the controller 20.
The proper lower limit position is calculated, and the upper mold 13 is lowered to the proper lower limit position. Therefore, the setting change of the lower limit position of the upper die 12, in other words, the setting change of the engagement amount between the upper die 13 and the lower die 11 becomes easy.

[0023]

As is apparent from the above description, the present invention uses a servomotor as a drive source of the upper die, calculates the lower limit position of the upper die, and controls the lower limit position to be the proper lower limit position. The position of the upper die is determined by detecting the load torque applied to the servomotor and determining whether or not there is a press failure. Therefore, there is an excellent effect that the mold can be prevented from being damaged.

[Brief description of the drawings]

FIG. 1 is a block diagram of a control system showing one embodiment of the present invention.

FIG. 2 is a side view showing a schematic configuration.

FIG. 3 is a diagram showing load torque characteristics;

FIG. 4 is a longitudinal sectional view of a main part of an upper mold and a lower mold showing a state of detachment of a resin beam.

FIG. 5 is a perspective view of a main part of a lead frame showing a conventional state in which a resin flash is attached.

FIG. 6 is a longitudinal sectional view of the same.

FIG. 7 is a longitudinal sectional view of a main part of an upper mold and a lower mold showing a state of detachment of a resin beam.

FIG. 8 is a perspective view of a main part of a lead frame in a state where a resin burr is detached.

FIG. 9 is a side view showing a schematic configuration of a crank press.

[Explanation of symbols]

11 is a lower mold, 13 is an upper mold, 16 is a ball screw, 17 is a servomotor, 18 is a timing belt, 19 is a screw rod,
Reference numeral 20 denotes a controller (position control means, determination means, operation control means), and reference numeral 21 denotes a servo amplifier (torque detection means).

Claims (1)

(57) [Claims] A servo for moving the upper die up and down, wherein the resin flash attached to the resin-sealed semiconductor lead frame is released by a press die having an upper die and a lower die. A motor, position control means for calculating the proper lower limit position of the upper die and controlling the servo motor so as to be at the proper lower limit position; torque detecting means for detecting a load torque of the servo motor; Semiconductor resin deburring device comprising: a judging means for judging the presence or absence of a press abnormality based on the torque detected by the means; and an operation control means for stopping the operation of the servomotor when the press abnormality is judged by the judging means. .