KR101551351B1 - Method for Inspecting Lead Frame of LED - Google Patents

Abstract

The present invention relates to a method of inspecting an LED lead frame, and more particularly, to an LED lead frame inspecting method for obtaining an image and determining whether an LED chip disposed in a lead frame is defective and marking the LED chip. The inspection method includes loading a magazine containing a plurality of lead frames and loading each lead frame into a conveyance path; Wherein each of the lead frames is divided into at least one region along a transfer path to be subjected to line scan to acquire an image; Determining whether the image is defective or not and displaying on the chip pad of each lead frame; Each lead frame being discharged along a different discharge path according to the display; And separating the lead frames discharged along the different discharge paths by separators.

Description

{Method for Inspecting Lead Frame of LED}

The present invention relates to a method of inspecting an LED lead frame, and more particularly, to an LED lead frame inspecting method for obtaining an image to determine whether or not a chip pad disposed in a lead frame is defective and marking the chip pad.

A lead frame corresponding to a main component of the semiconductor package has a function of a lead for connecting the semiconductor chip and an external circuit, and a frame for fixing the package to the electronic circuit board. Also, since the LED lead frame may have a function of reflecting light from the LED package, the reflectance characteristic may affect the light output characteristic of the LED.

In general, the LED leadframe can be made of an alloy of copper-iron-phosphorous, copper-nickel-silicon or iron-nickel and has physical properties such as mechanical strength, electrical conductivity, thermal conductivity, thermal expansion coefficient, oxidation resistance, heat resistance or corrosion resistance Or chemical properties. The defects generated in such an LED lead frame may lead to a total failure of the LED package, and therefore it is necessary to conduct inspection in advance.

As a prior art related to the inspection of the LED package, Patent Publication No. 2010-0098884 has a strip inspection apparatus for manufacturing an LED package. The prior art relates to a strip inspection apparatus for manufacturing an LED package, comprising: a supply side magazine unit for supplying a strip to be inspected; A transfer unit for sequentially transferring the strip supplied from the supply side magazine unit to the inspection position, the marking position and the unloading position; An inspection camera module that scans the surface of the strip transferred to the inspection position to inspect whether each LED package is defective and outputs a defect signal to each LED package; A marker for displaying a bad mark on an LED package corresponding to a bad signal inputted from the inspection camera module when the strip of the inspection position is fed to the marking position; And a discharge-side magazine unit for receiving and storing a strip conveyed from the marking position to the unloading position.

Another prior art related to LED inspection is Patent Publication No. 2012-0054834 'LED Vision Inspection System'. The prior art includes a loader unit for sequentially supplying LED strip products to be inspected; The strips and individual chips of the LED strip supplied through the loader unit are photographed using a camera to inspect the appearance (liquid flow / excess liquid / underflow) and chip position and wire bending conditions unit; A test result imprinting unit for receiving the good / bad result information of the inspected product in the inspection unit and imprinting the defective condition on each chip in which the defect has occurred using the laser; A material reversing unit for inverting the LED strip product discharged from the imprinting unit for backside marking; A laser marking unit for marking a product unique number on the back surface of the inverted LED strip product in the material inversion unit using a laser; A marking inspection unit for inspecting the state stamped on the LED strip in the laser marking unit using a camera; And a transfer unit for sequentially transferring the product supplied from the loader unit to the inspection unit, the inspection unit, the material reversing unit, the laser marking unit and the marking inspection unit using a conveyor belt .

The method related to the LED inspection of the prior art does not disclose a specific method of inspecting each chip pad of the lead frame and does not disclose a lead frame inspection method that enables precise continuous inspection without any error .

The present invention has been made to solve the problems of the prior art and has the following purpose.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an LED lead frame inspecting method capable of automatically and precisely inspecting a scratch generated in a lead frame or a defect occurring in each chip pad continuously and automatically.

According to a preferred embodiment of the present invention, the inspection method is characterized in that a magazine accommodating a plurality of lead frames is inserted and each of the lead frames is loaded on a conveyance path; Wherein each of the lead frames is divided into at least one region along a transfer path to be line scanned to acquire an image; Determining whether the image is defective or not and displaying on the chip pad of each lead frame; Each lead frame being discharged along a different discharge path according to the display; And separating the lead frames discharged along the different discharge paths by separators.

According to another preferred embodiment of the present invention, the region divided into the at least one region is acquired at a time interval.

According to another preferred embodiment of the present invention, whether or not the obtained image is defective is determined by optical characteristics of the chip pad.

The inspection method according to the present invention has an advantage that accurate inspection of the LED lead frame is possible. In addition, the inspection method according to the present invention has an advantage that productivity can be improved by enabling continuous automatic inspection. In addition, the inspection method according to the present invention has an advantage in that various types of LED-related devices can be inspected through design changes. In addition, the inspection method according to the present invention has an advantage that an inspection error due to interference is reduced by dividing a region and acquiring an image by an optical camera disposed at different positions.

FIG. 1A shows an embodiment of a process according to an inspection method of the present invention.
FIG. 1B shows an embodiment of a lead frame to which the inspection method according to the invention can be applied, and FIG. 1C shows an embodiment of a chip pad and a bad chip pad arranged in FIG. 1B.
2A and 2B illustrate an embodiment of a testing apparatus for an inspection method according to the present invention.
3A shows an embodiment of an image acquisition module for an inspection method according to the present invention.
FIG. 3B illustrates an embodiment of a marking module for an inspection method according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the accompanying drawings, but the present invention is not limited thereto. In the following description, components having the same reference numerals in different drawings have similar functions, so that they will not be described repeatedly unless necessary for an understanding of the invention, and the known components will be briefly described or omitted. However, It should not be understood as being excluded from the embodiment of Fig.

FIG. 1A shows an embodiment of a process according to an inspection method according to the present invention.

Referring to FIG. 1A, the inspection method according to the present invention includes loading a magazine containing a plurality of lead frames (S11) and loading each of the lead frames into a conveyance path (S13); Wherein each of the lead frames is divided into at least one region along a transfer path and each divided region is line scanned to acquire an image (S14); A step S16 of judging whether or not the obtained image is defective (S15) and displaying the result on a chip pad of each lead frame; A step (S17) of discharging each lead frame along a different discharge path according to the display state; And a step (S18) in which the lead frames discharged along the different discharge paths are separated and stacked by the separator.

The inspection method according to the present invention can be applied, for example, for inspection of a lead frame as shown in FIG. 1B. A method according to the present invention is a scratch generated in a lead frame. The defect is judged based on the obtained image obtained basically for inspection of cracks, partial breakage or defective chip pad. For example, an image obtained by an image acquisition device such as a camera can be transmitted to a control unit and can be compared with a sample image. Then, it is judged whether there is a defect according to the comparison result.

The type of defect that can be determined by the inspection method according to the present invention is not particularly limited, and the image contrast method can be performed according to any method known in the art. The type of the lead frame that can be inspected by the inspection method according to the present invention is not limited and can be applied to the inspection of any lead frame through appropriate design change.

A plurality of lead frames can be accommodated in the magazine and the lead frame can be inserted into the inspection area by the transfer of the magazine and the withdrawal of the lead frame from the magazine. The structure of the magazine is not particularly limited and may be any structure capable of automatic feeding and discharging, and at the same time, each lead frame from the magazine can be drawn out in a predetermined order.

The magazine can be supplied to the inspection area through an appropriate path (S11) and each lead frame can be cleaned in the transferring process (S12). The cleaning may be a static elimination method such as ion blowing. The static electricity present in the lead frame makes it difficult to pull out the lead frame, making it difficult to transport along an accurate feed path, or it can cause interference in the image acquisition process. Air cleaning may also be performed to remove foreign matter present on the surface of the lead frame. Various cleaning methods can be applied to the cleaning process according to the present invention.

When the cleaning process is completed (S12), each lead frame is separated from the magazine and can be loaded on the conveying means (S13). According to the invention, the leadframe can be conveyed along the conveying conveyor, but can preferably be conveyed by the conveying carrier. The conveying carrier can have a structure capable of being fixed along the conveying conveyor, which is capable of being fixed to the lead frame and which, at the same time, is operated by a device such as a motor. Carriers having various structures can be applied to the method according to the present invention.

When the lead frame is moved to the inspection area by the transport carrier, an image can be obtained (S14). According to the present invention, the lead frame can be divided into at least one region or three regions along the transport direction or the longitudinal direction of the lead frame, and the image for each region can be independently obtained by different optical cameras . The different regions may be physically separated by the lead frame or artificially formed in a program form. As described above, various advantages can be generated by dividing the region along the direction of the line scan or the transfer direction, and independently obtaining the image and making the determination. This division of the area enables the camera to be downsized and the installation space to be reduced. For example, a plurality of cameras may be arranged in a diagonal direction with respect to the transport direction, and an image for a predetermined area from each camera may be obtained. Such an arrangement of the cameras can reduce interference by allowing different areas to be line scanned at different times. In addition, the inspection of the divided areas thus arranged has an advantage that it is possible to make a quick determination in the control module. It is possible to arrange various regions or optical cameras for each region, and the present invention is not limited to the embodiments shown.

The image may be obtained, for example, by an image acquisition device such as an optical camera (S14), and the obtained image may be transmitted to the control module to determine whether it is defective (S15). For example, a standard image can be prepared in the control module and data for various types of defects can be stored. For example, information relating to color, illuminance or transmittance can be obtained in the obtained image and compared with a standard image or a predetermined color, illuminance or transmittance range. And a failure judgment may be made for an area outside the predetermined range. As described above, whether or not a defect is caused may be optical characteristics for the obtained image, but the present invention is not limited thereto. Various image comparison methods can be applied to the inspection method according to the present invention.

If it is judged that each lead frame is defective and stored, the defective sector of the lead frame may be displayed according to the related information (S16). And the lead frame that is displayed or not displayed may be transferred to the pickup position (S17). At the pick-up position, each lead frame can be separated into different discharge paths depending on whether the lead frames are defective or not, for example, by a device such as a robot arm (S18). The separated lead frame can then be discharged along an appropriate discharge path.

An embodiment in which the lead frame is divided in the inspection method according to the present invention will be described below.

FIG. 1B shows an embodiment of a lead frame 10 to which the inspection method according to the invention can be applied, and FIG. 1C shows an embodiment of a chip pad and a bad chip pad arranged in FIG. 1B.

Referring to FIGS. 1B and 1C, the chip pads 111 may be arranged in a matrix form on the frame 11 of the lead frame 10, and the bad sectors may be marked.

On the other hand, the chip pad 111 may be composed of a base 111a and a bond 111b and may be divided into a plurality of optical areas LA1 and LA2.

The lead frame 10 may be divided into three regions A1, A2, and A3 by the separation lines L1 and L2 along the transport direction T, as shown in FIG. 1B. Each of the areas A, A2, and A3 can be line scanned with a time difference by different optical cameras. And may be a bad marking 112 for the chip pads 111 disposed in each of them. In this specification, the time difference means that images are obtained at different times for the chip pads located on the same line in the direction perpendicular to the longitudinal direction of the lead frame.

Referring to FIG. 1C, data according to the defective shapes DE1, DE2, DE3 can be stored and each of the obtained images can be compared with the standard data. Depending on the level of match, it can be determined whether it is bad or not. Such a level of matching can be based on optical properties as described above.

Various types of bad data can be prepared, and accordingly, it is possible to judge whether or not it is bad according to any method known in the art, and the present invention is not limited to the embodiments shown.

Hereinafter, a test apparatus to which the method according to the present invention can be applied will be described.

2A and 2B illustrate an embodiment of a testing apparatus for an inspection method according to the present invention.

2A and 2B, an inspection device 20 of an LED lead frame includes a supply guide 211 for moving a magazine M accommodating a plurality of lead frames, a magazine M A supply module 21 consisting of a lifting unit 212 for lifting the lead frame, a lifting unit 213 for moving each lead frame to the magazine M, and a loader for lifting each lead frame moved by the lifting unit 113; An image acquisition module (22) having at least one camera for acquiring an image for each lead frame transferred from the supply module (21); A marking module (23) capable of marking a specific chip pad arranged on the lead frame according to the inspection result obtained from the image acquisition module (22); And a discharging module (24) for sorting the lead frame transferred from the marking module (23) according to the inspection result, and separating the sorted lead frames from the discharging magazine by the separator transferred from the separator unit (245) Is loaded on the carrier 25 and is conveyed along the conveying conveyor 26.

As described above, the inspection apparatus 20 can detect the scratches generated in the lead frame. Cracks, partial breakage or defective chip pads, and basically judges the defect based on the image obtained from the image acquisition module 22. [0050] The image obtained by the image acquisition module 22 can be transmitted to the control unit and compared with the sample image. Then, it is judged whether there is a defect according to the comparison result. The type of defect that can be determined by the inspection apparatus 20 is not particularly limited, and the image contrast method may be performed according to any method known in the art. The type of the lead frame that can be inspected by the inspection apparatus 20 is not limited and can be applied to inspection of any lead frame through appropriate design change.

The lead frame can be plate-shaped and can be accommodated in such a manner that a plurality of lead frames are stacked on the magazine M. [ The magazine M can be moved along the feed guide 211 formed in the feed module 21 and the plurality of magazines M can be moved in turn. The inspection apparatus 10 may be installed in the closed space R and a part of the insertion module 21 may be exposed to the outside or may be exposed by the door that can be opened or closed. The entire operation can be controlled by an externally installed control module.

The cleaning process can be performed on the magazine M moved along the supply guide 211. [ The cleaning process may be performed for each lead frame or for the magazine M and for example an ion blowing process may be used. The magazine that has been cleaned can be moved to a position determined by the lift unit 212.

Each of the lead frames located inside the magazine M moved to the position determined by the elevating unit 212 can be inserted into the inspection process by the jumping unit 213. Specifically, the jamming unit 213 can be installed so as to be movable up and down, and can have a structure capable of sequentially pushing the respective lead frames inside the magazine. The pushed lead frame can then be loaded into the loader. And the load frame allows the lead frame to be transported along the insertion guide 214 and moved along the transport conveyor 26 by the carrier 25.

The empty magazine M having exhausted the used lead frame can be discharged through the discharge guide 215 and can be filled with the lead frame again. A width adjusting unit for adjusting the interval of the magazine M may be installed in the discharge guide 215 as needed. Each of the devices including the supply module 21 can be installed in the frame F and the entire device can be installed in the closed space R as described above.

Each lead frame supplied from the input module 21 can be loaded on the carrier 25 and transferred along the transfer conveyor 26 to the image acquisition module 22. [

The image acquisition module 22 may include a camera unit 221 in which at least one camera is disposed and a display 222 for confirming the status of a lead frame to be inspected. Each of the cameras disposed in the camera unit 221 may be disposed at different positions in a direction perpendicular to the extending direction of the conveying conveyor 26 or may have different angles for image acquisition. An image obtained at different positions or at different angles of the lead frame by at least one vision camera can be transmitted to the control module so that it can be compared with a standard image and thus a defect can be judged. Each lead frame may have a unique identification number and the chip pads included in each lead frame may also have a respective unique identification number. And if there is a part that is judged to be defective or suspected to be defective, it is stored and the relevant data can be transferred to the marking module 23. Or the control module can thereby control the operation of the marking module 23.

The number or arrangement of cameras that can be installed in the image acquisition module 22 is not particularly limited, and the present invention is not limited to the embodiments shown.

The lead frame having been inspected in the image acquiring module 22 can be moved along the conveying conveyor 26 and transferred to the marking module 23. The marking module 23 may include a head unit 232 having at least two nozzles and a positioning unit 231 for determining the position of the head unit 232. The positioning unit 231 may move along the XY plane along the transfer arm and the head unit 232 may mark the predetermined position of the lead frame based on the bad data transmitted from the control module. And the lead frame marked in the required position can be transferred to the discharge module 24. [

The discharging module 24 includes a discharging robot 241 having a pick-up unit 242 movable along the Z-axis direction to pick up the lead frame and movable along the XY plane, a lead frame A first discharge guide 243a for transferring a lead frame having a defective portion and a first discharge guide 243b for transferring a lead frame having a defective portion and a separator unit 245 accommodating spacing paper for separating the respective lead frames .

The lead frame conveyed by the carrier 25 from the marking module 23 is picked up by the pick-up unit 242 and can be loaded into any one of the discharge trays T1 and T2 depending on whether or not the defective portion is included have. The discharge trays T1 and T2 may have a receiving box capable of accommodating a plurality of lead frames and may have a structure capable of moving along the first discharge guide 243a and the second discharge guide 243b. When the discharge trays T1 and T2 are moved to the predetermined positions, the separator is picked up from the separator unit 245 and placed in a collector (not shown). Then, one lead frame is again discharged from the discharge trays T1 and T2 It can be picked up and accommodated in the collector. In this way, the lead frames accommodated in the respective discharge trays T1 and T2 can be separated by the separator and accommodated in the collector.

Apparatuses known in the art such as, for example, servo motors, air cylinders or belts may be used for the operation of the inspection apparatus. Therefore, the inspection apparatus according to the present invention is not limited by the type or arrangement structure of the apparatus for driving or conveying.

Each of the devices that can be applied to the inspection apparatus 20 will be described below.

3A shows an embodiment of an image acquisition module for an inspection method according to the present invention.

3A, the lead frame is fixed to the carrier 25 and can be conveyed along the conveying rod 33, and the camera unit 221 is projected forward by the fixed frame 321, And at least one vision camera 322 disposed above the camera 322.

The feed rod 33 may be composed of a fixed plate 331 and a rod plate 332 extending along the feeding direction so that the fixed plate 331 and the fixed plate 331 can be moved up and down. The carrier 25 includes a loading body 251 fixed to the rod plate 332 so as to be movable and a space adjusting plate 252 disposed in front of the loading body 251 to allow the lead frame to be aligned along the lateral direction. (252).

The cameras may be at least one, for example three, and may be arranged at different positions in the longitudinal direction and at different positions in the direction perpendicular to the longitudinal direction. The three cameras can obtain images of different parts of the lead frame, which are line scans, or images of different angles. For example, three cameras can obtain the images of the top surface of the lead frame, the lead frame mold, and the bottom surface of the lead frame, respectively. Alternatively, the three cameras can obtain images of different regions of the divided lead frame as described above.

A suitable focal length for image acquisition can be determined by determining the vertical position of the carrier 25 by the rod plate 332 and the position of the X-Y plane of the lead frame can be fixed by the spacing plate 252. [ The carrier 25 is moved along the load plate 332 by the conveying conveyor so that the lead frame is line scanned and images of different angles or angles are acquired by each camera and transmitted to the control module . Then, the control module determines whether a specific position of the lead frame is defective based on the transmitted image. The carrier 25 can then be transferred to the marking module.

FIG. 3B illustrates an embodiment of a marking module for an inspection method according to the present invention.

3B, the marking module 23 includes first and second guides 271a and 271b disposed along the XY axis, a positioning unit (not shown) fixed to the moving bracket so as to be movable along the first guide 271a, 273 and a nozzle head 272.

The carrier, which is moved along the transporting conveyor 26 in a state where the lead frame is loaded, can be fixed to the fixed unit 274. When the carrier is fixed, the first guide 271a moves to a predetermined position along the second guide 271b according to the control of the control module, and then the moving bracket moves again. Then, the nozzle head 272 moves up and down by the positioning unit 273, and can be marked at a predetermined position of the lead frame. The nozzle head 272 may have at least one nozzle and may display states such as, for example, defects, retest requests, or inspection failures in different colors.

The marking module 23 may have various structures and the present invention is not limited to the embodiments shown.

The inspection method according to the present invention has an advantage that accurate inspection of the inspection of the LED lead frame is possible. In addition, the inspection method according to the present invention has an advantage that productivity can be improved by enabling continuous automatic inspection. In addition, the inspection method according to the present invention has an advantage in that various types of LED-related devices can be inspected through design changes. In addition, the inspection method according to the present invention has an advantage that an inspection error is reduced due to interference by dividing a region and acquiring an image by an optical camera disposed at different positions.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention . The invention is not limited by these variations and modifications, but is limited only by the claims appended hereto.

10: lead frame 11: frame
20: Inspection device 21: Supply module
22: image acquisition module 23: marking module
24: exhaust module 25: carrier
26: conveying conveyor 33: conveying rod
111: chip pad 111a: base
111b: Bond 211: Supply guide
212: lift unit 213:
214: Injection guide 215: Discharge guide
245: Kanji unit 221: Camera unit
222: display 231: positioning unit
232: Head unit 241: Discharge robot
242: pick-up unit 251: loading body
252: spacing plate 272: nozzle head
273: Positioning unit 274: Fixing unit
321: fixed frame 322: vision camera
331: Fixing plate 332: Rod plate

Claims (3)

A magazine containing a plurality of lead frames each having a chip pad arranged in a matrix form is cleaned and transported by a carrier by an ion implantation process;
Wherein each of the lead frames is divided into at least one region along a transfer path to be a line scan and image acquisition of each of the divided regions;
Determining whether the obtained image is defective and being displayed on the chip pad of each lead frame according to a position determined by a movable unit capable of moving along an XY plane;
Each lead frame being discharged along a different discharge path according to the display; And
And the lead frames being discharged along the different discharge paths are separated and stacked by the separator,
Wherein the plurality of cameras for line scan of the at least one area are arranged diagonally with respect to the conveying direction, the magazine is moved up and down by the elevating unit to a predetermined position, and each of the lead frames accommodated in the magazine Wherein the carrier is loaded on the loader by a vertically movable jig unit and is received in the carrier. The method of claim 1, wherein the plurality of cameras have different image acquisition angles. delete

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