JPH09275175A - Lead forming machine for semiconductor devices and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lead forming machine for semiconductor devices and control method therefor which improves the outer lead forming accuracy by equalizing working conditions. SOLUTION: A press mechanism controller 2 controls a press mechanism 3 for driving dies 4 for bending and forming outer leads of a semiconductor device such that a speed control system is applied during a bending work from the driving start of the dies 4 until approximately specified shape of the leads is attained, and a pressure control system is applied during a forming work to form the leads into a specified shape. Owing to the speed control system for the bending work, a stable work can be made at a fixed speed and the bending start position setting can be easily and accurately made to realize equalized working conditions, and owing to the pressure control system for the forming work, the formation at a fixed pressure can be made with reference of accurately determined forming start position, thus improving the forming accuracy of the leads.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device lead processing apparatus for processing external leads of a semiconductor device into a predetermined shape and a control method thereof.

[0002]

2. Description of the Related Art Conventionally, a resin-encapsulated package semiconductor device has a package formed on a multiple lead frame on which semiconductor element pellets are mounted, and a plurality of external leads extending from the package are connected to a semiconductor device lead processing apparatus. Punching with a press mechanism die, for example, gull wing shape (L
It is formed by bending into a letter shape.

The press mechanism of the lead processing apparatus for forming the gull-wing-shaped bending process moves up and down by driving the movable mold by a pressure control system using a hydraulic cylinder or the like, or a position control system using a servo motor. It is operated to perform punching and bending of external leads.

An example of bending the outer leads of a semiconductor device into a gull wing shape in the prior art will be described below with reference to FIGS. 9 and 10. FIG. 9 is a view showing a change in processing speed in a lead processing apparatus for a pressure control type semiconductor device, and FIG. 10 is a view showing a change in processing pressure in a lead processing apparatus for a position control type semiconductor device.

First, when an external lead is bent and formed into a gull-wing shape in a pressure-controlled semiconductor device lead processing apparatus, all processing is performed within one stroke of a movable die by a hydraulic cylinder. Then, in this processing process, the reaction force from the external lead, which is the workpiece, changes depending on the content to be processed, the processing speed curve X becomes as shown in FIG. 9, and the processing speed is in the middle of the processing speed curve X. It is unstable as shown by the curved portion A of the part.

That is, the processing speed increases linearly until the movable die touches the external lead after the processing is started. When the movable die touches the external lead and punches it out, and the bending process of the base part on the package side starts, the machining speed decreases, and the tip of the external lead touches the fixed die, and the middle of the external lead When the bending of the part is also added, the processing speed becomes slower. Then, due to the difference in the processing pressure due to the number of external leads and the stress history up to the previous process, the processing speed becomes unstable and the processing conditions become non-uniform.

On the other hand, in the case where the external leads are similarly bent and formed into a gull wing shape in the pressure control type semiconductor device lead processing apparatus, the processing is performed at substantially the same speed in one stroke of the movable mold by the servo motor. Done in. Then, the processing pressure curve Y in this processing process is as shown in FIG. 10, and the final processing pressure for forming after bending the intermediate portion of the external lead is as shown in the processing pressure curve Y in the range B, for example. It will be scattered and unstable.

That is, when the movable die comes into contact with the external lead to start the processing, the processing pressure rapidly increases, and when the bending of the base portion of the external lead on the package side is started, the processing pressure slightly decreases. . Further, the processing pressure increases with the tip of the external lead touching the fixed mold, and the bending process of the middle part of the external lead is also applied, and then the processing pressure increases to make the external lead a final shape. Final processing pressure is applied. Then, the final processing pressure varies depending on the thickness of the external lead, the height of the mold set in the pressing mechanism, etc., and the processing conditions become non-uniform.

As described above, in the conventional semiconductor device lead processing apparatus using the pressure control method or the position control method, processing is performed by the difference in the processing stress due to the number of external leads provided in the semiconductor device and the stress history up to the previous process. The speed became unstable, or the processing start position and the final processing pressure fluctuated depending on the thickness of the external lead and the height variation of the entire die, resulting in non-uniform processing conditions.

[0010]

When molding the external leads of the semiconductor device as described above, the processing speed becomes unstable due to the difference in the processing stress in the processing by the lead processing apparatus of the semiconductor device by the pressure control method. Alternatively, in the processing by the lead processing apparatus of the semiconductor device by the position control method, the processing start position and the final processing pressure are varied, and the processing conditions are not uniform. The present invention has been made in view of such circumstances, and an object of the present invention is to provide a semiconductor device capable of performing molding with improved processing accuracy of external leads of the semiconductor device under uniformized processing conditions. It is to provide a lead processing apparatus and a control method thereof.

[0011]

A semiconductor device lead processing apparatus and method for controlling the same according to the present invention include a die for bending and forming external leads of a semiconductor device, and a press for driving the die up and down. Mechanism, displacement detector that detects the vertical position of the mold, pressure detector that detects the pressure applied to the mold, press mechanism is controlled by speed control method and pressure control method, and displacement detector and pressure A press mechanism control unit that controls the press mechanism according to the detection output of the detector is provided, and the press mechanism bends after the drive of the mold is started by the press mechanism control unit until the external leads have a substantially predetermined shape. It is characterized in that control is performed by a speed control method during processing, and that control is performed by a pressure control method in molding processing for forming into a predetermined shape. In addition, in a method of controlling a lead processing device of a semiconductor device, in which a pressing mechanism is controlled so that the external leads of the semiconductor device have a predetermined shape, and bending and forming are performed by a die, the pressing mechanism is controlled by a speed control method. After performing the bending process and performing the bending process, when the processing pressure reaches a predetermined pressure, the control is switched to the pressure control method so that the processing pressure is continuously applied for a predetermined time to perform the forming process. In addition, at least one speed inflection point is included in the process of controlling the press mechanism by the speed control method, and the speed at which the driving of the mold is started is controlled to a constant speed. Further, the processing start position is detected in the constant speed region in the process of controlling the press mechanism by the speed control method, and the external lead of the external lead is referenced based on the processing start position. It is characterized in that the working conditions are set, and a die for bending and forming the external leads of the semiconductor device, a press mechanism for vertically driving the die, and a vertical movement of the die. Displacement detector that detects the position in the direction, pressure detector that detects the pressure applied to the mold, press mechanism is controlled by speed control method and pressure control method, and according to the detection output of displacement detector and pressure detector And a press mechanism control unit for controlling the press mechanism.

The lead processing apparatus for a semiconductor device and the control method therefor configured as described above control the press mechanism for driving the die for bending and forming the external leads of the semiconductor device by controlling the press mechanism. The part is controlled by the speed control method during the bending process from the start of driving the die until the external lead has a substantially predetermined shape, and the pressure control method is used for the molding processing for forming the external shape. Therefore, in bending, it is possible to perform processing at a stable constant speed by controlling with a speed control method, and it becomes possible to set the processing start position easily and accurately and Uniformity can be realized, and in the molding process, the pressure control method is used to accurately set the constant pressure for machining. It will be able to do so, to improve machining accuracy of the outer leads.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIG.
This will be described with reference to FIGS. FIG. 1 is a block diagram showing the outline of a lead processing apparatus for a semiconductor device, FIG. 2 is a sectional view of an essential part showing a processing process of external lead molding, and FIG. 3 is a flow chart of control of the processing process. 4 is a diagram showing the displacement state of the press mechanism, FIG. 5 is a diagram showing the output of the displacement detector of the press mechanism, FIG. 6 is a diagram showing the output of the pressure detector of the press mechanism, and FIG. It is a figure which shows the processing speed change of a press mechanism, and FIG. 8 is a figure which shows the processing pressure change of a press mechanism.

1 to 8, a lead processing apparatus 1 for a semiconductor device is provided with a press mechanism 3 and a die 4 which move up and down under speed control and pressure control by a control signal from a press mechanism control unit 2. Is configured. The die 4 is composed of an upper pressing die 7 and a lower pressing die 8 for fixing the semiconductor device 5 which is a workpiece and the external leads 6 thereof, and a movable die 9 driven by the vertical movement of the pressing mechanism 3. ing.

Further, the press mechanism 3 is provided with a displacement detector 10 for detecting the vertical position of the movable mold 9 and a pressure detector 11 for detecting the pressure applied to the movable mold 9 during processing. Further, the displacement detector 10 and the pressure detector 11
The displacement signal and the pressure signal detected by each of the above are output to the press mechanism control unit 2. The pressure detector 11 for detecting the pressure applied to the movable mold 9 is, for example, a detector configured to detect a reaction force from the movable mold 9 generated during processing, and the displacement detector 10 includes: For example, there is a detector configured to electrically or optically detect the relative positional relationship between the movable mold 9 and the external lead 6, and other known detectors may be used.

Next, regarding the processing process of external lead molding of the lead processing apparatus 1 for such a semiconductor device, a sectional view of the main part of the processing process shown in FIG. 2 and a flow chart shown in FIG. A description will be given with reference to the diagram showing the displacement state of the press mechanism, the diagram showing the output of the displacement detector of FIG. 5, and the diagram showing the output of the pressure detector of FIG.

First, in the first step S ₁ , the processing conditions such as the operating position of the press mechanism 3, the processing speed, the processing pressure and the processing time are set to the press mechanism control unit 2. Then, the resin-sealed semiconductor device 5 in which the external leads 6 are not molded is fixed by the upper pressing die 7 and the lower pressing die 8 of the die 4. Usually, the semiconductor device 5 is formed in a multiple lead frame.

In the following second step S ₂ , the movable mold 9 is lowered at a preset first relatively fast constant speed V ₁ while starting the operation of the press mechanism 3 and controlling the speed. Let

In the next third step S ₃ , whether or not the movable mold 9 has reached the approach position M of the preset displacement h _M is determined based on the detection result of the displacement detector 10. The approach position M is, for example, the movable mold 9
And the external lead 6 which is the work piece come into contact with each other at a position 0.1 mm before the contact position N of the displacement h _N. The elapsed time to the approach position M is defined as time t _M. When the movable mold 9 reaches the approach position, the next fourth
The process proceeds to step S _4, if it does not reach to continue the lowering of the second step S ₂ of the movable mold 9.

Next, in the fourth step S ₄ , when the movable mold 9 reaches the approach position M, the control of the operation of the press mechanism 3 is speed control and pressure control. Under the speed control and pressure control, The movable mold 9 is moved down, for example, by switching to a constant speed of a preset second speed V ₂ . Here, the second speed V ₂ is an appropriate speed in the later-described bending work, and is the first speed for reaching the approach position M.
The speed is slower than the speed V ₁ .

Then, in a fifth step S ₅ , it is judged whether or not the movable mold 9 has reached the contact position N where the movable lead 9 contacts the external lead 6. When the movable mold 9 reaches the contact position N, the process proceeds to step S ₆ of the sixth following, if not reached to continue the descent of the movable mold 9 in the fourth step S _4. The time t _N is the elapsed time until the movable mold 9 reaches the contact position N.

Next sixth in step S ₆ of starts processing of the external lead 6 by the movable mold 9, the speed control and the movable mold to the original pressure control in the second constant rate of velocity V ₂ 9 To lower and continue processing. The processing starts with punching and first bending at the root-side intermediate portion of the outer lead 6, and when the tip of the outer lead 6 contacts the lower presser die 8 by the first bending, the tip of the outer lead 6 is further cut. The second bending process at the side intermediate portion is started. Then, the outer lead 6 is formed into a gull wing shape by the first bending process and the second bending process.

[0023] In a seventh step S ₇ that follows, either movable mold 9 is whether the host vehicle has reached the end position O of the displacement h _O of lead processing determination, processing pressure reaches a predetermined final pressure P not This is performed by detecting whether or not it is detected by the pressure detector 11. The displacement h _N to the displacement h _O is the processing stroke H of the external lead 6 by the movable mold 9. Proceeds to step S ₈ of the eighth following when the movable mold 9 reaches the end position O, if not reached to continue the process of lowering the movable mold 9 in step S ₆ of the sixth .

Next in step S ₈ of the eighth, the control of the operation of the press mechanism 3 and the pressure control, the final while maintaining the pressure P is positioned to continue the movable mold 9 to the end position O to the external lead A molding process for pressing 6 is performed.

[0025] In step S ₉ of the ninth for determining whether or not the pressing of the external lead 6 of maintaining the final pressure P by the movable mold 9 continues from time t _O a predetermined time T is performed . When the pressing of the external lead 6 by the final pressure P continues for a predetermined time T, the process proceeds to step S ₁₀ of the first 10 of the next, if not reach Step S ₈ of the eighth
The pressing by the final pressing force P of No. is continued. The time t _Q is the elapsed time from the time t _O of the final pressurizing force P to the time point when it is maintained for the predetermined time T.

Next in step S ₁₀ of the first 10, and a speed control to control the operation of the press mechanism 3, and ends the processing of movable mold 9 is raised at a third velocity V _3.

2A is a sectional view showing a state where the movable mold 9 reaches the contact position N, and FIG. 2B is a sectional view showing the movable mold 9 during the first bending process. 2 (c) is a cross-sectional view of the movable mold 9 during molding.

The changes in the processing speed and the processing pressure during the processing of the external lead 6 are shown by the processing speed curve X ₀ shown in FIG.
And the processing pressure curve Y ₀ shown in FIG. That is, the punching to the first bending and the second bending are performed at a constant speed. During this period, the processing pressure rises at the initial point of the start of the first bending, but when the bending starts, the processing pressure gradually decreases. When the second bending process is started at the tip end side intermediate portion of the outer lead 6, the working pressure rises again.

When the movable mold 9 reaches the bottom dead center and the outer lead 6 is molded into a substantially predetermined gull wing shape, the processing pressure at that time is maintained for a predetermined time, and the molding process is performed. This gives the outer leads 6 the final gull wing shape.

As described above, in punching and bending, it is possible to perform processing at a constant speed by controlling the speed, and in forming processing, it is possible to perform processing at a constant pressure by controlling the pressure. Does not become unstable, and by setting the processing start position (contact position N) and the final processing pressure P in advance, variations in the thickness of the external leads 6 and the height of the mold 4 as a whole, etc. It is possible to prevent non-uniformity of the processing conditions due to, and further, it is possible to optimize the processing conditions so as to be appropriate, and it is possible to improve the processing accuracy of the external leads and obtain a final shape with less variation.

[0031]

As is apparent from the above description, according to the present invention, a press mechanism for driving a die for bending and forming external leads of a semiconductor device is driven by a press mechanism controller. During the bending process from the start to the time when the external lead has a substantially predetermined shape, the speed control method is used for control, and the pressure control method is used for the molding process for forming the wire to have the predetermined shape. Is uniformized, and the processing accuracy of the external leads is improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an outline of a semiconductor device lead processing apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a main part showing a processing process of external lead molding in an embodiment of the present invention, and FIG. 2A is a cross-sectional view showing a state where a movable mold 9 reaches a contact position N, Two
FIG. 2B is a sectional view of the movable die 9 during the first bending process, and FIG. 2C is a sectional view of the movable die 9 during the forming process.

FIG. 3 is a flow chart of control of a machining process according to the embodiment of the present invention.

FIG. 4 is a diagram showing a displacement state of the press mechanism according to the embodiment of the present invention.

FIG. 5 is a diagram showing an output of the displacement detector of the press mechanism according to the embodiment of the present invention.

FIG. 6 is a diagram showing an output of the pressure detector of the press mechanism according to the embodiment of the present invention.

FIG. 7 is a diagram showing a change in processing speed of the press mechanism according to the embodiment of the present invention.

FIG. 8 is a diagram showing a processing pressure change of the press mechanism according to the embodiment of the present invention.

FIG. 9 is a diagram showing a change in processing speed in a conventional lead processing apparatus for a pressure control type semiconductor device.

FIG. 10 is a diagram showing a processing pressure change in a conventional lead processing apparatus for a position control type semiconductor device.

[Explanation of symbols]

 2 ... Press mechanism control unit 3 ... Press mechanism 4 ... Mold 5 ... Semiconductor device 6 ... External lead 7 ... Top pressing mold 8 ... Bottom pressing mold 9 ... Movable mold 10 ... Displacement detector 11 ... Pressure detector

Claims (5)

[Claims] 1. A mold for bending and forming an external lead of a semiconductor device, a press mechanism for vertically driving the mold, and a displacement detector for detecting the vertical position of the mold. A pressure detector that detects the pressure applied to the mold, and a press that controls the press mechanism by a speed control method and a pressure control method and controls the press mechanism according to the detection outputs of the displacement detector and the pressure detector. A mechanism control unit, and the press mechanism is controlled by a speed control method during the bending process from the start of the driving of the mold by the press mechanism control unit until the outer lead has a substantially predetermined shape. A lead processing apparatus for a semiconductor device, wherein a molding process for molding into a predetermined shape is controlled by a pressure control method. 2. A method of controlling a lead processing apparatus for a semiconductor device, wherein a press mechanism is controlled so that an external lead of the semiconductor device has a predetermined shape, and a bending process and a forming process are performed by a die, wherein the press mechanism is controlled by a speed control method. After the processing is started and the bending is performed, when the processing pressure reaches a predetermined pressure, the control is switched to the pressure control method, and the processing pressure is continuously applied for a predetermined time to perform the forming processing. A method for controlling a semiconductor device lead processing apparatus, comprising: 3. A speed control system having at least one speed inflection point in the process of controlling the press mechanism by a speed control method, and the speed at which the driving of the mold is started is controlled to a constant speed. A method for controlling a lead processing apparatus for a semiconductor device according to claim 2. 4. The processing start position is detected in a constant speed region in the process of controlling the press mechanism by a speed control method, and the processing conditions of the external lead are set on the basis of the processing start position. The method for controlling a lead processing apparatus for a semiconductor device according to claim 2, wherein 5. A die for bending and forming an external lead of a semiconductor device, a press mechanism for vertically driving the die, and a displacement detector for detecting a vertical position of the die. A pressure detector that detects the pressure applied to the mold, and a press that controls the press mechanism by a speed control method and a pressure control method and controls the press mechanism according to the detection outputs of the displacement detector and the pressure detector. A lead processing apparatus for a semiconductor device, comprising: a mechanism control unit.