Technical Field

The present invention relates to a feeding apparatus and a feeding method for semiconductor lead frames. More particularly, the present invention relates to an apparatus for feeding semiconductor lead frames to a press unit by receiving the semiconductor lead frames from an on-loader unit.

Background Art In general, a semiconductor package is produced through various fabrication processes of preparing a semiconductor chip including a silicon semiconductor substrate formed with highly integrated circuits, such as transistors and capacitors, attaching the semiconductor chip to a lead frame or a printed circuit board, electrically connecting the semiconductor chip to the lead frame or the printed circuit using wires, and molding the semiconductor chip with EMC (epoxy molding compound) such that the semiconductor chip can be protected from external environment. Such a packaged semiconductor lead frame is divided into individual semiconductor lead frames through a trimming

process, a forming process, and a singulation process and then the individual semiconductor lead frames are off-loaded from the semiconductor fabrication device. Generally, the above trimming, forming and singulation processes are performed by means of a press unit including an upper mold and a lower mold, so an apparatus for feeding the semiconductor lead frames to the press unit is necessary.

In the meantime, an example of a feeding apparatus for semiconductor lead frames is illustrated in FIGS. 9a to 13b of Korean Patent Application No. 10-1996-0064585 (Registration No. 10-0215937), which has been filed by applicant of the present invention with a title "Apparatus for manufacturing a semiconductor lead frame". Hereinafter, description will be made in relation to the apparatus for manufacturing a semiconductor lead frame disclosed in Korean Patent Application No. 10-1996-0064585 while focusing on a feeding apparatus for semiconductor lead frames provided in the above apparatus.

FIG. 1 is a plan view illustrating the conventional apparatus for manufacturing a semiconductor lead frame and FIG. 2 is a front view of the conventional apparatus for manufacturing a semiconductor lead frame shown in FIG. 1.

As shown in FIGS. 1 and 2, the conventional apparatus for manufacturing a semiconductor ^' lead frame mainly includes an on-loader unit 100, a lead frame feeding unit, and a

press unit 200. Herein, since the lead frame (L) travels from the on-loader unit 100 to the press unit 200, portions of elements adjacent to the on-loader unit 100 will be defined as "upstream portions" and portions of elements adjacent to the press unit 100 will be defined as "downstream portions". In addition, when describing an element having two opposite end portions, one end portion adjacent to an upstream portion of the element will be referred to as a "front end" and the other end portion adjacent to a downstream portion of the element will be referred to as a "rear end".

First, the on-loader unit 100 is provided with lead frames L to be processed and loads the lead frames L onto the lead frame feeding unit under a predetermined condition. The on-loader unit 100 includes a magazine (not shown) having a plurality of lead frames L and an elevator (not shown) for lifting the lead frames stacked in the magazine up to a working position.

The press unit 200 receives the lead frames L from the lead frame feeding unit and divides the lead frames L into individual semiconductor chips through the interaction between upper and lower molds 212 and 214, which are aligned in opposition to each other.

The lead frame feeding unit receives the lead frames L from the on-loader unit 100 and transfers the lead frames L

to the press unit 200. The lead frame feeding unit mainly includes a conveyer device 300, a plotter 400, and a feeder 500.

The conveyer device 300 conveys the lead frame L toward the plotter 400 when the lead frame L is loaded thereon by means of the on-loaded unit 100. The conveyer device 300 has a conveyer belt 314 for conveying the lead frame L loaded thereon.

In addition, as shown in FIG. 3, a first stopper 320 is installed at a rear end of the conveyer device 300 so as to control the feeding time of the lead frame L to the plotter 400. A first sensor 330 is provided in the vicinity of an upstream portion of the first stopper 320 so as to check whether the lead frame L is normally transferred to the first stopper 320. A second sensor 340 is provided in the vicinity of a downstream portion of the first stopper 320 so as to check whether the lead frame L has moved beyond the first stopper 320. Herein, the first stopper 320 moves up and down by means of a first cylinder (not shown) . In addition, as shown in FIG. 4, a roller unit is installed at a rear end of the conveyer device 300 in order to feed the lead frame L into the plotter 400. The roller unit includes a driving roller 350 for providing the driving force for the lead frames L and an idle roller 360 engaged with the driving roller 350 so as to feed the lead frames L.

The idle roller 360 is elastically biased in the downward direction by means of a spring and repeatedly moves up and down in cooperation with the up/down movement of the plotter 400 by means of an idle lift (not shown) installed in the plotter 400.

The plotter 400 guides the lead frames L while repeatedly moving up and down by means of a vertical conveying unit 420 coupled with a spindle. The plotter 400 consists of an upper plotter 412 and a lower plotter 414 aligned corresponding to the upper plotter 412. The lead frame L is guided through a -guide slot 416 formed between the upper and lower plotters 412 and 414. The upper plotter 412 is formed at both sides thereof with elongation holes 418 aligned lengthwise along the upper plotter 412. In addition, an idle lifter (not shown) is installed at a front end of the lower plotter 414 so as to move the idle roller 360 up and down in cooperation with the plotter 400. That is, when the plotter 400 moves up, the idle lifter (not shown) also moves up while lifting the idle roller 360 upward. Thus, the idle roller 360 is spaced apart from the driving roller 350 by a predetermined distance. In contrast, when the plotter 400 moves down, the idle lifter (not shown) also moves up while moving the idle roller 360 downward. Thus, the idle roller 360 elastically makes contact with the driving roller 350, thereby transferring the lead frames L.

Meanwhile, as shown in FIGS. 3 and 4, a second stopper 430 is provided at a front end of the plotter 400 so as to stop the movement of the lead frame L when the plotter 400 moves up and a third stopper 440 is installed next to the second stopper 430 according to the process order in order to stop the movement of the lead frame L when the plotter 400 moves down. Similar to the idle roller 360, the second and third stoppers 430 and 440 repeatedly move up and down in cooperation with the up/down movement of the plotter 400 so as to stop the movement of the lead frame L. To this end, the second stopper 430 is elastically installed at a lower portion of the plotter 400 so as to stop the movement of the lead frame when the plotter 400 moves up, and the third stopper 440 is elastically installed on a base 230 of the press unit 200 so as to stop the movement of the lead frame L when the plotter 400 moves down.

In addition, a third sensor 452 is provided in the vicinity of an upstream portion of the third stopper 440 so as to check whether the lead frame L has moved beyond the third stopper 440. When the third sensor 452 detects the lead frame L, which has moved beyond the third stopper 440, the first stopper 320 moves down so that the lead frame L is transferred toward the second stopper 430. In the meantime, the third sensor 452 also checks whether the front end of the lead frame L normally reaches the third stopper 440.

A pin 510 is provxded at a front end of the feeder 500 in such a manner that the pin 510 can be inserted into an insertion hole 102 through the elongation hole 418 formed in the upper plotter 412. In addition, the feeder 500 is coupled with a spindle (not shown) such that the feeder 500 can operate m cooperation with the plotter 400. The feeder 500 repeatedly reciprocates in the process direction, thereby transferring the lead frame L in the downstream direction by one pitch unit. The press unit 200, the plotter 400, the second stopper 430 and the idle roller 360 are connected to a cam drive unit (unit) coupled to the spindle (not shown) , so that they may cooperate with each other.

Hereinafter, the operation of the conventional lead frame feeding unit having the above structure will be described. For the purpose of convenience of explanation, a lead frame, which is fed first, is referred to as a first lead frame Ll and a lead frame, which is fed after the first lead frame Ll, is referred to as a second lead frame L2. FIG. 5 is a flowchart illustrating an operational procedure of the conventional lead frame feeding unit shown in FIG. 1, and FIGS. 6 to 9 are schematic views illustrating the operational states of the conventional lead frame feeding unit. First, if the second sensor 340 provided in the

vicinity of the downstream portion of the first stopper 320 detects the first lead frame Ll, which has moved beyond the first stopper 320, the first stopper 320 is moved up by means of the first cylinder (not shown) . At this time, the second frame L2 loaded on the conveyer belt 314 by means of the on-loader unit 100 is transferred toward the first stopper 320 until it makes contact with the first stopper 320 (see, FIG. 6) . In the meantime, the first sensor 330 provided in the vicinity of the upstream portion of the first stopper 320 checks whether the second lead frame L2 is normally transferred to the first stopper 320 without an error. If it is determined that the second lead frame L2 is not normally transferred to the first stopper 320, an error message is displayed. In this state, if the third sensor 452 provided in the vicinity of the upstream portion of the third stopper 440 detects the rear end of the first lead frame Ll, which has moved beyond the third stopper 440 by means of the feeder 500, the first stopper 320 is moved down by means of the first cylinder (not shown) and the second lead frame L2 makes contact with the second stopper 430 by means of a roller drive unit 354, so that the movement of the second lead frame L2 is stopped (see, FIG. 7) . At this time, the driving roller 350 of the roller drive unit 354 starts its operation (rotation) when the rear end of the first lead

frame Ll has passed through the third stopper 440 and ends its operation when the front end of the second lead frame L2 reaches the third stopper 440.

In this state, if the plotter 400 moves down, the second stopper 430 also moves down so that the second lead frame L2 is transferred to the third stopper 440 by means of the roller drive unit 354 (see, FIG. 8) .

At this time, the third sensor 452 checks whether the front end of the second lead frame L2 normally reaches the third stopper 440 without an error. If it is determined that the second lead frame L2 is not normally transferred to the third stopper 440, an error message is displayed.

Then, if the plotter 400 moves up, the third stopper 440 also moves up, so that the second lead frame L2 is fed into the press unit 200 by one pitch unit by means of the feeder 500 installed in the press unit 200 (see, FIG. 9) .

In this manner, the conventional lead frame feeding unit may feed a new lead frame into the press unit by- controlling the operation of the second stopper 430, the third stopper 440 and the idle roller 360 in cooperation with the up/down movement of the plotter 400.

However, according to the conventional lead frame feeding unit, the second lead frame L2 is transferred toward the second stopper 430 after the first stopper 320 moves down when it is detected that the first lead frame Ll has

moved beyond the third stopper 440 by the third sensor 452 provided in the vicinity of the upstream portion of the third stopper 440. Then, the second lead frame L2 is transferred to the third stopper 440 after the second stopper 430 moves down together with the plotter 400. Accordingly, the second lead frame L2 may not be rapidly fed into the third stopper 440. That is, a time delay may occur when the lead frame is fed from the first stopper 320 to the second stopper 430. In addition, since the third stopper 440 fixed to the base 230 operates corresponding to the up/down movement of the plotter 400, the feeder 500 may transfer the lead frame only when the plotter 400 has been moved upward. That is, although it is possible for the feeder 500 to transfer the lead frame when the pin 510 of the feeder 500 is inserted into the insertion hole 102 of the lead frame L, in practice, the feeder 500 transfers the lead frame L when the lead frame L has moved beyond the third stopper 400 after the plotter 400 sufficiently moves upward. Thus, a time delay may occur when transferring the lead frame to the press unit.

In addition, since the second stopper 430 is used to hold the lead frame before the lead frame is fed into the third stopper 440 so as to rapidly feed the lead frame into the third stopper 440. Thus, it is not necessary to move the second stopper 430 up and down if the lead frame has been

fed into the third stopper 440. Similarly, the idle roller 360 operates in cooperation with the driving roller 350 in order to feed the lead frame to the second and third stoppers 430 and 440. Thus, it is not necessary to repeatedly move up and down if the front end of the lead frame has passed through the third stopper 440. Such an up/down movement of the second stopper 430 and the idle roller 360 may be incurred because the second stopper 430 and the idle roller 360 are designed such that they are operated in cooperation with the plotter 400. Due to the up/down movement of the second stopper 430 and the idle roller 360, vibration is unnecessarily generated from the lead frame, thereby causing the slip of the lead frame.

Disclosure of the Invention

Therefore, the present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a feeding apparatus and a feeding method for lead frames in order to rapidly feed the lead frames into a press unit without generating vibration in the lead frames by driving stoppers and sensors using a separate driving unit such that the stoppers and sensors are operated separately from a plotter.

In order to accomplish the above object, according to one aspect of the present invention, there is provided an

apparatus for feeding a semiconductor lead frame from an on- loader unit to a press unit, the apparatus comprising: a second stopper installed on a front end of a plotter of the press unit and individually driven by means of a separate drive unit in order to control a feeding time for the lead frame to a third stopper installed adjacent to an upstream portion of a pressing area formed in the press unit; and a third sensor installed adjacent to the second stopper so as to check whether a rear end of the lead frame has moved beyond the second stopper, wherein when the third sensor detects that the rear end of the lead frame has moved beyond the second stopper, a new lead frame is fed toward the second stopper.

The second stopper includes a stopper arm having an actuating part rotatably coupled to a lower portion of the plotter so as to receive a driving force, a protrusion part protruding upward from the actuating part so as to block the lead frame, and an elastic support part extending downward from the actuating part so as to receive an elastic force, a second elastic unit coupled to the elastic support part so as to apply an elastic force to the stopper arm, and a second cylinder coupled with the actuating part so as to apply an actuating force to the stopper arm.

A fourth sensor is installed adjacent to the third stopper in order to check whether the rear end of the led

frame has moved beyond the third stopper. When the fourth sensor detects that the rear end of the lead frame has moved beyond the third stopper, the lead frame is fed blocked by the second stopper is fed toward the third stopper. The second stopper is maintained in a move-down position until the rear end of the lead frame has moved beyond the second stopper.

A roller unit is installed at a rear end of a conveyer device of the on-loader unit in order to feed the lead frame to the second and third stoppers. The roller unit includes a driving roller for providing a driving force for the lead frame and an idle roller installed corresponding to the driving roller and individually driven by a separate driving unit so as to feed the lead frame while engaging with the driving roller.

The idle roller engages with the driving roller when it is necessary to feed the lead frame to the second and third stoppers and is spaced apart from the driving roller when a front end of the lead frame has moved beyond the third stopper.

According to another aspect of the present invention, there is provided an apparatus for feeding a semiconductor lead frame from an on-loader unit to a press unit, the apparatus comprising: a first stopper installed at a rear end of a conveyer device connected to the on-loader unit so

as to control a feeding time for the lead frame to a plotter of the press unit; a third stopper installed adjacent to an upstream portion of a pressing area of the press unit in order to control a feeding time for the lead frame to the pressing area of the press unit; a second stopper installed adjacent to an upstream portion of the third stopper so as to control a feeding time for the lead frame to the third stopper; a third sensor installed adjacent to the second stopper so as to check whether a rear end of the lead frame has moved beyond the second stopper; a fourth sensor installed adjacent to the third stopper in order to check whether the rear end of the led frame has moved beyond the third stopper, wherein the first to third stoppers are individually operated by means of a separate driving unit, which is controlled according to signals transmitted from the third sensor or the fourth sensor.

According to still another aspect of the present invention, there is provided a method for feeding a semiconductor lead frame from an on-loader unit to a press unit, the method comprising the steps of: detecting whether a rear end of the lead frame has moved beyond a second stopper installed at a front end of a plotter of the press unit; and instantly feeding a new lead frame toward the second stopper when it is determined that the rear ^' end of the lead frame has moved beyond the second stopper.

The method further comprises the steps of detecting whether the rear end of the lead frame has moved beyond a third stopper installed adjacent to an upstream portion of a pressing area of the press unit; and instantly feeding the lead frame aligned at the second stopper toward the third stopper when it is determined that the rear end of the lead frame has moved beyond the third stopper.

Brief Description of the Drawings The foregoing and other objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which:

FIG. 1 is a plan view illustrating a conventional apparatus for manufacturing a semiconductor lead frame including a lead frame feeding unit;

FIG. 2 is a front view of a conventional apparatus for manufacturing a semiconductor lead frame shown in FIG. 1;

FIG. 3 is an enlarged plan view illustrating an alignment of stoppers and sensors installed in a conventional lead frame feeding unit shown in FIG. 1;

FIG. 4 is an enlarged plan view illustrating an alignment of second and third stoppers and a roller unit installed in a conventional lead frame feeding unit shown in FIG. 1;

FIG. 5 is a flowchart illustrating an operational procedure of a conventional lead frame feeding unit shown in FIG. 1;

FIGS. 6 to 9 are schematic views illustrating operational states of a conventional lead frame feeding unit shown in FIG. 1;

FIG. 10 is a plan view illustrating an apparatus for manufacturing a semiconductor lead frame including a lead frame feeding unit according to one embodiment of the present invention;

FIG. 11 is a front view of an apparatus for manufacturing a semiconductor lead frame shown in FIG. 10;

FIG. 12 is an enlarged plan view illustrating an alignment of stoppers and sensors installed in a lead frame feeding unit shown in FIG. 10;

FIG. 13 is an enlarged plan view illustrating an alignment of second and third stoppers and a roller unit installed in a lead frame feeding unit shown in FIG. 10;

FIG. 14 is a front view illustrating an idle roller and an idle roller drive unit according to one embodiment of the present invention;

FIG. 15 is a front view illustrating an idle roller and an idle roller drive unit according to another embodiment of the present invention; FIG. 16 is a view illustrating the operational state

of the second and third stoppers;

FIG. 17 is a sectional view illustrating an installation method for second and third stoppers and third and fourth sensors; FIG. 18 is a flowchart illustrating an operational procedure of a lead frame feeding unit shown in FIG. 10; and FIGS. 19 to 23 are schematic views illustrating the operational state of a lead frame feeding unit shown in FIG. 10.

Best Mode for Carrying Out the Invention

Hereinafter, preferred embodiments of the present invention will be described with reference to accompanying drawings.

Since a lead frame travels from an on-loader unit 100 to a press unit 200, portions of elements adjacent to the on-loader unit 100 will be defined as "upstream portions" and portions of elements adjacent to the press unit 100 will be defined as "downstream portions". In addition, when explaining an element having two opposite end portions, one end portion adjacent to an upstream portion of the element will be referred to as a "front end" and the other end portion adjacent to a downstream portion of the element will be referred to as a "rear end". In addition, the same

reference numerals will be assigned to the same elements throughout the specification for the purpose of convenience of explanation.

FIG. 10 is a plan view illustrating an apparatus for manufacturing a semiconductor lead frame including a lead frame feeding unit according to one embodiment of the present invention and FIG. 11 is a front view of the apparatus for manufacturing a semiconductor lead frame shown in FIG. 10. As shown in FIG. 10, the apparatus for manufacturing a semiconductor lead frame mainly includes the on-loader unit 100, the press unit 200, the lead frame feeding unit, and a control unit (not shown) for controlling the operation of the above elements. Since the structure and operation of the on-loader unit 100 and the press unit 200 are substantially identical to those of the prior art, they will be briefly described below and the following description will be focused on the lead frame feeding unit, which is a main element according to the present invention. First, as shown in FIG. 10, the on-loader unit 100 is provided with lead frames L to be processed and loads the lead frames L onto the lead frame feeding unit under a predetermined condition. The on-loader unit 100 includes a magazine (not shown) having a plurality of lead frames L and an elevator (not shown) for lifting the lead frames stacked

in the magazine up to a working position. In the meantime, the structure of the on-loader unit 100 can be variously designed so long as it can load the lead frames onto the lead frame feeding unit under the predetermined condition. As shown in FIG. 11, the press unit 200 receives the lead frames L from the lead frame feeding unit and divides the lead frames L into individual semiconductor chips through the interaction between upper and lower molds 212 and 214, which are aligned in opposition to each other. Herein, an area formed between the upper and lower molds 212 and 214 is defined as a pressing area, in which the lead frame is processed.

The lead frame feeding unit receives the lead frames L from the on-loader unit 100 and transfers the lead frames L to the press unit 200. The lead frame feeding unit mainly includes a conveyer device 300, a plotter 400, and a feeder 500.

The conveyer device 300 conveys the lead frame L toward the plotter 400 when the lead frame L is loaded thereon by means of the on-loaded unit 100. The conveyer device 300 has a conveyer frame 310, a conveyer roller 312 rotatably installed in the conveyer frame 310, a conveyer belt 314 installed on the conveyer roller 312 for conveying the lead frame L loaded thereon, and a conveyer drive unit 316 for providing the driving force for the conveyer roller

312 .

In addition, as shown in FIG. 12, a first stopper 320 is installed at a rear end of the conveyer device 300 so as to control the feeding time of the lead frame L, which is conveyed by means of the conveyer belt 314, to the plotter 400. The first stopper 320 is connected to a first cylinder 322, which is operated under the control of the control unit. The first stopper 320 moves up and down by means of the first cylinder 322 so that the first stopper 320 protrudes upward from the conveyer device 300 and returns to its initial position, thereby controlling the movement of the lead frame L, which moves along the conveyer device 300. The first cylinder 322 can be fabricated in the form of a rotary cylinder operated by means of pneumatic pressure or can be actuated by means of a solenoid.

In addition, a first sensor 330 is provided in the vicinity of an upstream portion of the first stopper 320 so as to check whether the lead frame L is normally transferred to the first stopper 320. A second sensor 340 is provided in the vicinity of a downstream portion of the first stopper 320 so as to check whether the lead frame L has moved beyond the first stopper 320.

In addition, as shown in FIG. 12, a roller unit is installed at a rear end of the conveyer device 300 in opposition to the first stopper 320 in order to feed the

lead frame L into the plotter 400. The roller unit includes a driving roller 350 connected to a roller drive unit 354 in order to provide the driving force for the lead frames L and an idle roller 360 engaged with the driving roller 350 so as to feed the lead frames L.

Referring to FIG. 14, the idle roller 360 includes an idle bracket 362 coupled to the conveyer frame 310. The center portion of an idle arm 364 is hinged to the idle bracket 362. The idle roller 360 is rotatably coupled to one end of the idle arm 364. The other end of the idle arm 364 is elastically biased in the downward direction by means of an elastic member 366 and upwardly urged by means of an idle drive unit 368 operated under the control of the control unit. The idle drive unit 368 includes an air cylinder, a hydraulic cylinder or a solenoid.

When the control unit generates a lead frame feeding signal, the idle drive unit 368 rotates the idle arm 364 in the counterclockwise direction, so that the idle roller 360 moves down while pressing the lead frame. In this state, if the driving roller 350 is rotated, the lead frame is fed toward the second stopper 430 or the third stopper 440 by means of the idle roller 360 engaged with the driving roller 350. Meanwhile, if it is not necessary to feed the lead frame, the driving force of the idle drive unit 368 is released, so that the idle arm 364 moves up while rotating

in the clockwise direction due to the elastic force of the elastic member 366, thereby stopping the feed for the lead frames.

The idle roller 360 moves down until the lead frame reaches the third stopper 440. Then, the idle roller 360 is controlled such that it can be maintained in a move-up state. That is, according to the present invention, the idle roller 360 is controlled by means of the idle drive unit 368, which is operated regardless of the up/down movement of the plotter 400. Thus, it is not necessary to separately install the idle lifter, which repeatedly moves up and down the idle roller 360 in cooperation with the plotter 400. Accordingly, when the lead frame has entered the press unit 200, the idle roller 360 is spaced apart from the driving roller 350, so that vibration is not generated in the lead frame, thereby preventing the lead frame from slipping.

Meanwhile, as shown in FIG. 15, the position of the elastic member 366 and the idle drive unit 366 of the idle roller 360 can be interchanged. The plotter 400 guides the lead frames while repeatedly moving up and down by means of a vertical conveying unit 420, which operates in cooperation with a cam drive unit (not shown) coupled with a spindle (not shown) .

As shown in FIGS. 10 and 11, the plotter 400 consists of an upper plotter 412 and a lower plotter 414 aligned

corresponding to the upper plotter 412. The lead frame L is guided through a guide slot 416 formed between the upper and lower plotters 412 and 414. The upper plotter 412 is formed at both sides thereof with elongation holes 418 aligned lengthwise along the upper plotter 412. In addition, the lower plotter 414 is formed with a stopper hole 418 into which protrusions 433 of the second and third stoppers 430 and 440 are inserted (see, FIG. 17) .

In addition, as shown in FIGS. 12 and 13, the third stopper 440 is installed in the vicinity of an upstream portion of the pressing area formed in the press unit 200 so as to control the feeding time of the lead frame to the press unit 200. The second stopper 430 is installed in the vicinity of an upstream portion of the third stopper 440 so as to control the feeding time of the lead frame to the third stopper 440. That is, the second stopper 430 holds the lead frame in the vicinity of the upstream portion of the third stopper 440 so as to rapidly feed the lead frame to the third stopper 440 and the third stopper 440 holds the lead frame in the vicinity of the upstream portion of the pressing area in the press unit 200 so as to rapidly feed the lead frame to the press unit 200.

As shown in FIGS. 16 and 17, the second stopper 430 includes a stopper arm 432 the center portion of which is rotatably coupled to a lower portion of the lower plotter

414, a second elastic member 436 for applying the bias force to the stopper arm 432, and a second cylinder 438 for actuating the stopper arm 432. The stopper arm 432 includes the protrusion part 433 protruding upward from one end of the stopper arm 432 so as to block the lead frame, an actuating part 434 extending from the other end of the stopper arm 432 so as to receive driving force from the second cylinder 438, and an elastic support part 435 extending downward from the stopper arm 432 such that the elastic force of the second elastic member 436 can be applied to the elastic support part 435. The second stopper 430 has a symmetrical structure widthwise along the plotter 400. Preferably, the second cylinder 438 includes a pneumatic cylinder. However, it is also possible to fabricate the second cylinder 438 in the form of a hydraulic cylinder or a solenoid cylinder.

The second stopper 430 having the above structure is inserted into or withdrawn from the stopper hole 419 of the plotter 400 according to the operation of the second cylinder 438 under the control of the control unit, thereby restricting/allowing the movement of the lead frame L. That is, when air is fed into the second cylinder 438 under the control of the control unit, the actuating part 434 of the stopper arm 432 may move upward due to pneumatic pressure applied thereto, so that the stopper arm 432 rotates in the

clockwise direction. Thus, the protrusion part 433 of the stopper arm 432 moves down while opening the stopper hole 419. In contrast, if the air being fed into the second cylinder 438 is shut off under the control of the control unit, the elastic support part 435 is biased due to the elastic force applied thereto from the second elastic member 436, so that the stopper arm 432 rotates in the counterclockwise direction. Thus, the protrusion part 433 of the stopper arm 432 moves up while closing the stopper hole 419 (see, FIG. 17) .

The structure and mechanism of the third stopper 440 are substantially identical to those of the second stopper 430, so they will not be further described below in order to avoid redundancy. Different from the prior art, the up/down movement the second and third stoppers 430 and 440 may not cooperate with the up/down movement of the plotter 400. That is, the second and third stoppers 430 and 440 control the movement of the lead frame according to the control signal of the control unit separately from the up/down movement of the plotter 400. Since the second and third stoppers 430 and 440 are operated by means of a separate driving unit under the control of the control unit, they can rapidly stop the movement of the lead frame without causing vibration of the lead frame. Although it is illustrated that the second and third

stoppers 430 and 440 are installed at the lower portion of the plotter 400, they can be aligned in various positions according to applications thereof. In addition, the structure and the shape of the second and third stoppers 430 and 440 can be variously modified so long as they can control the movement of the lead frame under the control of the control unit.

In addition, a third sensor 450 is provided in the vicinity of a downstream portion of the second stopper 430 so as to check whether the rear end of the lead frame has moved beyond the second stopper 430. If the third sensor 450 detects the lead frame L, which has moved beyond the second stopper 430, the first stopper 320 moves down and the second stopper 430 moves up under the control of the control unit. Thus, a new lead frame blocked by the first stopper 320 is transferred toward the second stopper 430 from the first stopper 320 and makes contact with the second stopper 430. That is, since the new lead frame is fed into the second stopper 430 as soon as the lead frame, which has entered the press unit 200, moves beyond the second stopper 430, the feeding speed for the lead frame can be improved. However, although the third sensor 450 installed in the vicinity of the downstream portion of the second stopper 430 can detect the lead frame, which has moved beyond the second stopper 430, it is impossible for the third sensor 450 to check

whether the new lead frame safely reaches the second stopper 430.

Meanwhile, the third sensor 450 can be installed in the vicinity of an upstream portion of the second stopper 430 depending on applications thereof. In this case, the third sensor 450 can detect not only the lead frame, which has moved beyond the second stopper 430, but also the new lead frame arrived at the second stopper 430. At this time, the second stopper 430 may not move up even if the rear end of the lead frame has passed the third sensor 450. That is, preferably, an encoder of a driving motor for the feeder 500 of the press unit 200 detects the position of the feeder 500 in such a manner that the second stopper 430 can be moved up after the lead frame has moved beyond the second stopper 430. In this case, the second stopper 430 may not cause vibration of the lead frame.

In addition, a fourth sensor 460 is provided in the vicinity of an upstream portion of the third stopper 440 so as to check whether the rear end of the lead frame, which enters the pressing area of the press unit 200, has moved beyond the third stopper 440. When the fourth sensor 460 detects the lead frame, which has moved beyond the third stopper 440, the second stopper 430 moves down and the third stopper 440 moves up under the control of the control unit. Thus, the lead frame blocked by the second stopper 430 is

transferred toward the third stopper 440 from the second stopper 430. In the meantime, the fourth sensor 460 also checks whether the frond end of the new frame normally reaches the third stopper 440. Meanwhile, the fourth sensor 460 can be installed in the vicinity of a downstream portion of the third stopper 440 depending on applications thereof. However, in this case, the fourth sensor 460 cannot detect the new lead frame in the vicinity of the upstream portion of the third stopper 440. Thus, it is necessary to install an additional sensor in the vicinity of the upstream portion of the third stopper 440 in order to detect the new lead frame arrived at the third stopper 440.

In addition, as shown in FIG. 16, the third and fourth sensors 450 and 460 are installed on a sensor frame 480 fixed to the plotter 400 so as to facilitate maintenance and repair work for the third and fourth sensors 450 and 460. However, the installation position of the third and fourth sensors 450 and 460 can be variously selected so long as they can easily detect the position of the lead frame.

In this manner, when the third sensor 450 detects the lead frame, which has moved beyond the second stopper 430, the first stopper 320 moves down so that the new lead frame is instantly fed into the second stopper 430. In addition, when the fourth sensor 460 detects the lead frame, which has

moved beyond the third stopper 440, the second stopper 430 moves down so that the lead frame is instantly fed into the third stopper 440. Accordingly, it is possible to rapidly and continuously feed the lead frames. In addition, a direction detect sensor 470 can be further installed between the second and third stoppers 430 and 440 so as to detect whether the position of the lead frame being moved toward the plotter 400 of the press unit 200 is correct or not. The feeder 500 is aligned at an upper portion of the plotter 400 and repeatedly reciprocates in the process direction in cooperation with the rotation of the spindle (not shown) installed in the press unit 200, thereby transferring the lead frame in the downstream direction by one pitch unit. A pin 510 is provided at a front end of the feeder 500 in such a manner that the pin 510 can be inserted into an insertion hole 102 formed at both sides of the lead frame L through the elongation hole 418 formed in the upper plotter 412. When the plotter 400 moves up, the pin 510 of the feeder 500 is inserted into the insertion hole 102 of the lead frame L, so that the lead frame L is moved in the downstream direction by one pitch unit. In addition, when the plotter 400 moves down, the pin 510 of the feeder 500 is released from the insertion hole 102 and horizontally

returns to its initial position. Such a movement of the pin 510 may be repeatedly carried out.

Hereinafter, the operation of the lead frame feeding unit having the above structure will be described. For the purpose of convenience of explanation, a lead frame, which is fed first, is referred to as a first lead frame Ll and a lead frame, which is fed after the first lead frame Ll, is referred to as a second lead frame L2.

FIG. 18 is a flowchart illustrating an operational procedure of the lead frame feeding unit according to one embodiment of the present invention and FIGS. 19 to 22 are schematic views illustrating the operational states of the lead frame feeding unit according to one embodiment of the present invention. First, if the second sensor 340 provided in the vicinity of the downstream portion of the first stopper 320 detects the first lead frame Ll, which has moved beyond the first stopper 320, the first stopper 320 is moved up by means of the first cylinder 322. At this time, the second frame L2 loaded on the conveyer belt 314 by means of the on- loader unit 100 is transferred toward the first stopper 320 until it makes contact with the first stopper 320 (see, FIG. 19) .

In the meantime, the first sensor 330 provided in the vicinity of the upstream portion of the first stopper 320

checks whether the second lead frame L2 is normally transferred to the first stopper 320 without an error. If it is determined that the second lead frame L2 is not normally transferred to the first stopper 320, an error message is displayed.

In this state, if the third sensor 450 provided in the vicinity of the downstream portion of the second stopper 430 detects that the rear end of the first lead frame Ll being fed in one pitch unit by means of the feeder 500 has moved beyond the second stopper 430, the first stopper 320 is moved down by means of the first cylinder 322 and the second stopper 430 is moved up by means of the second cylinder 438, so that the idle roller 360 is moved down. Thus, the idle roller 360 engages with the driving roller 350, so the second lead frame L2 is transferred toward the second stopper 430 by means of the idle roller 360 and makes contact with the second stopper 430, so that the movement of the second lead frame L2 is stopped (see, FIG. 20) .

In addition, if the fourth sensor 460 provided in the vicinity of the upstream portion of the third stopper 440 detects that the rear end of the first lead frame Ll being fed in one pitch unit by means of the feeder 500 has moved beyond the third stopper 430, the second stopper 430 is moved down by means of the second cylinder 438 and the third stopper 440 is moved up by means of the third cylinder (not

shown) , so that the idle roller 360 engages with the driving roller 350. Thus, the idle roller 360 rotates together with the driving roller 350, so the second lead frame L2 is transferred toward the third stopper 440 by means of the idle roller 360 and makes contact with the third stopper 440, so that the movement of the second lead frame L2 is stopped. At this time, the first lead frame Ll is fed toward the press unit 200 by one pitch unit.

In the meantime, the fourth sensor 460 provided in the vicinity of the upstream portion of the third stopper 440 checks whether the second lead frame L2 normally reaches the third stopper 440 without an error. If it is determined that the second lead frame L2 is not normally transferred to the third stopper 440, an error message is displayed. In this manner, if the plotter 400 moves up after the first lead frame Ll has been fed into the press unit 200, the idle roller 360 moves up by means of the idle drive unit 368 so that the idle roller 360 is spaced apart from the driving roller 350. At the same time, the third stopper 440 moves down by means of the third cylinder (not shown) and the second lead frame L2 is fed into the pressing area of the press unit 200 in one pitch unit by means of the feeder 500 installed in the press unit 200 (see, FIG. 23) . The lead frame fed into the pressing area of the press unit 200 is processed to have a predetermined shape and transferred to

the next stage.

The above procedure is repeatedly performed in order to feed the lead frame from the on-loader unit 100 to the press unit 200. While this invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiment and the drawings, but, on the contrary, it is intended to cover various modifications and variations within the spirit and scope of the appended claims.

Industrial Applicability As can be seen from the foregoing, according to the present invention, the second and third stoppers 430 and 440 may operate separately from the up/down movement of the plotter 400 and the lead frame is individually fed by means of a separate driving unit according to the position and feeding speed of the lead frame, so that the lead frames can be continuously fed into the press unit. Conventionally, the second and third stoppers 430 and 440 repeatedly move up and down corresponding to the up/down movement of the plotter 400, so the lead frame must wait for a predetermined time at the second stopper 430 or the third stopper 440 even if it is possible to instantly feed the lead frame. According to

the present invention, the second and third stoppers 430 and 440 are controlled in such a manner that the second lead frame can be instantly fed based on the status of the first lead frame. In addition, different from the prior art in which the lead frame is fed by means of the feeder 500 after the third stopper 440 has moved from the plotter 400, the present invention can move down the third stopper 440 even if the plotter 400 has not yet completely moved up because the third stopper 440 is driven by means of a separate driving unit. Thus, the third stopper 440 may move down as soon as the pin 510 of the feeder 500 is inserted into the insertion hole 102 of the lead frame, so that the lead frame can be rapidly fed by means of the feeder 500. According to the present invention, when the third sensor 450 installed in the vicinity of the second stopper 430 detects that the lead frame has moved beyond the second stopper 430, the new lead frame blocked by the first stopper 320 is instantly fed into the second stopper 430, so that the lead frame can be rapidly fed from the first stopper 320 to the second stopper 430.

In addition, according to the present invention, when the front end of the lead frame reaches the third stopper 440, the second and third stoppers 430 and 440 are maintained in the move-down position and the idle roller 360

is moved up while spacing from the driving roller 350. Thus, vibration of the lead frame caused by the up/down movement of the second and third stoppers 430 and 440 and the idle roller 360 may not be generated, so that the feeding error derived from the slip of the lead frame can be prevented.