KR20090042155A - Manufacturing method of flexible printed circuit board and inspection method thereof - Google Patents

Abstract

The present invention relates to a method for manufacturing a flexible printed circuit board and an inspection method thereof. The manufacturing method of the present invention can detect the quality of the circuit pattern in the optical inspection process and open or short defects, can reduce the manufacturing process, and can improve the yield in the subsequent process. The inspection method of the present invention acquires image data in units of pixels, measures in a direction perpendicular to the direction in which the width of a circuit pattern or a spatial component is measured, and detects a short if the measured width is a defect when the width is larger than the reference width. . In addition, in the inspection method of the present invention, if a defect in which the measured width is larger than the pixel size is not detected, the brightness level of the circuit pattern or the spatial component is analyzed in more detail in the vertical direction to detect the defect due to the open, short or residual copper foil. do. According to the present invention, it is possible to simplify the manufacturing process, increase the reliability in the inspection process, reduce the production cost, and improve the competitiveness of the manufacturer by minimizing the non-detection in the subsequent process.

Description

METHOD FOR MANUFACTURING FLEXIBLE PRINTED PRINTED CIRCUIT BOARD WITH ULTRA-FINE PATTERN AND METHOD FOR INSPECTING THEREOF}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor manufacturing process, and more particularly, to a manufacturing method of a flexible printed circuit board having an ultra fine circuit pattern, and an inspection method for opening or short detection of the ultra fine circuit pattern.

BACKGROUND ART With the miniaturization, weight reduction, and high functionality of electronic devices, printed circuit boards incorporating semiconductor devices are becoming increasingly smaller and lighter. To this end, the electronic device uses a flexible printed circuit board in the form of a tape or a film, such as a TAB and a chip on film (COF).

Recently, a display device uses a COF (Chip On Film) type flexible printed circuit board to mount a display driver IC (DDI). Such a flexible printed circuit board is used to realize cost reduction and high resolution display devices. For this reason, the line width of the circuit pattern is extremely small. Therefore, in order to detect defects occurring in the manufacturing process, a flexible printed circuit board generally uses optical to determine whether the circuit pattern is good or electrical inspection to check the open / short state of the circuit pattern. Detect. Finally, appearance inspection is carried out to determine whether or not it is ok.

In general, a method of manufacturing a flexible printed circuit board, first, an insulating layer is formed on a base substrate, a copper foil is provided on one side of the insulating layer, and a photoresist is applied on the copper foil. Subsequently, exposure and development processes are performed and patterned, and a circuit pattern is formed by etching copper foil using this patterned layer as a mask. Subsequently, after performing a peeling process, an optical inspection (AOI) for determining the quality of the circuit pattern is performed, the printed circuit board judged as good quality is plated, and then a solder resist is applied. Electrically check open / short status. After that, the external appearance is finally inspected and the goods are shipped.

In order to detect the open / short detection of a very fine circuit pattern, such a manufacturing method is primarily performed by optically inspecting a circuit pattern during the manufacturing process, and then electrically inspecting and detecting an undetected open / short defect by optical inspection. do.

For example, the optical inspection method acquires image data in units of pixels which are the minimum units, and measures the width of each pattern component and the spatial component and compares the reference value with the reference value to determine whether it is good or bad. However, as the manufacture of ultrafine circuit patterns increases, openings or shorts having a width smaller than one pixel exist between pixels and pixels, and such defects cannot be detected by conventional optical inspection methods. Therefore, an electrical inspection process for open / short detection is performed as a subsequent process in order to detect a defect of such an ultra fine circuit pattern.

As described above, the flexible printed circuit board for driving integrated circuits of display devices has recently formed an extremely fine circuit pattern, so that the open / short widths of the circuit pattern are extremely small, for example, about 2 micrometers (µm) or less. It exists, and the reliability of electrical inspection is falling. Particularly, in the process of electrically inspecting the existing open / short due to the miniaturization of the open / short width of the circuit pattern, the overdetection phenomenon which is actually good but defective is detected, or is actually defective but undetectable good. As the phenomenon increases exponentially, production cost increases and stable inspection quality cannot be obtained, which causes the competitiveness of the manufacturer.

An object of the present invention is to provide a method of manufacturing a flexible printed circuit board having an ultrafine circuit pattern using optical inspection to detect an open or short of a pattern component.

Another object of the present invention is to provide a method of inspecting a flexible printed circuit board having an ultrafine circuit pattern using optical inspection to detect an open or short of a pattern component.

It is still another object of the present invention to provide a method of manufacturing a flexible printed circuit board having an ultra fine circuit pattern which detects an open or short of a pattern component without an electrical inspection process and improves process simplification and product productivity, and an inspection method thereof. will be.

In order to achieve the above objects, an inspection method of a flexible printed circuit board of the present invention is to detect an open or a short of a circuit pattern by using an optical inspection, to obtain image data of the flexible printed circuit board on a pixel-by-pixel basis; Measuring a width of a circuit pattern and a space component between the circuit patterns in a first direction perpendicular to a direction in which the circuit pattern is formed for each unit pixel in the image data; If it is detected that the measurement width is larger than the reference width, it is determined as a short; If it is not detected that the measurement width is larger than the reference width, the brightness level is measured in the second direction perpendicular to the first direction, and if the measured brightness level is different from the ambient brightness level, it is determined to be defective. .

Here, if it is not detected that the measurement width is larger than the reference width, the brightness level for the spatial component is measured in the second direction, and if there is a portion where the measured brightness level is smaller than the ambient brightness level, it is determined as a short. Can be.

In addition, the short circuit determines the brightness level in the second direction based on the center pixel of the spatial component, and if the measured brightness level is smaller than the brightness levels of the other pixels, the brightness level is increased. The brightness level of the neighboring pixels of the small pixel is further measured to determine whether the brightness level of the neighboring pixels is smaller than the brightness level of the other pixels, and as a result of the determination, the brightness level of the neighboring pixels is smaller than the brightness level of the other pixels. If the brightness level of the neighboring pixels is not smaller than the brightness level of the other pixels, the remaining copper foil may be determined.

Further, the inspection method may further comprise: measuring a brightness level of the circuit pattern in the second direction in the image data; Determine whether there is a region where the measured brightness level is greater than the ambient brightness level; The determination result may further include determining that the pixel is open if the measured brightness level is larger than the ambient brightness level.

In addition, the method of manufacturing a flexible printed circuit board according to the present invention comprises the steps of forming an insulating layer on the base substrate; Installing copper foil on one side of the insulating layer; Applying a photo resist on the copper foil; Sequentially exposing, developing, etching, and peeling the substrate to form a circuit pattern; Optically inspecting an open or short state of the circuit pattern; And plating a substrate determined as good in the optical inspection, and applying a solder resist, wherein the open or short state of the circuit pattern is electrically inspected after applying the solder resist. The step of doing so is omitted.

Here, the optical inspection may detect an open or short state of a smaller size than the unit pixel in the circuit pattern.

In addition, the optical inspection acquires image data of the flexible printed circuit board in units of pixels, and the width of the circuit pattern for each unit pixel in the image data is in a first direction perpendicular to the direction in which the circuit pattern is formed. If it is measured and the measurement width for each unit pixel of the circuit pattern is larger than the reference width, it can be determined as a short.

Further, in the optical inspection, if there is no case where the measurement width of each unit pixel of the circuit pattern is larger than the reference width, the brightness of the pixels of the spatial component between the circuit patterns in the second direction perpendicular to the first direction By measuring the level, if a portion of the measured brightness level smaller than the other brightness level exists, it can be determined as a short.

In addition, the optical inspection may measure the brightness level for each pixel of the circuit pattern in the second direction, and if there is a portion in which the measured brightness level is greater than the other brightness level, the optical inspection may determine to be open.

As described above, the method for manufacturing and inspecting a flexible printed circuit board having an ultrafine circuit pattern according to the present invention is manufactured by simplifying a manufacturing process without an electrical inspection process by detecting an open or short of a pattern component using optical inspection. Cost savings can be achieved.

In addition, by performing the pattern optical inspection and the open or short optical inspection after the peeling process to improve the yield and inspection performance in the subsequent process, the manufacturer's competitiveness can be improved.

The embodiments of the present invention may be modified in various forms, and the scope of the present invention should not be interpreted as being limited by the embodiments described below. This embodiment is provided to more completely explain the present invention to those skilled in the art. Therefore, the shape of the components in the drawings, etc. have been exaggerated to emphasize a more clear description.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 10.

1 is a flowchart illustrating a manufacturing procedure of a flexible printed circuit board for a display driving chip having an ultrafine circuit pattern according to the present invention.

Referring to Figure 1, the manufacturing procedure of the flexible printed circuit board according to the present invention is applied to the photoresist on the base substrate on which copper foil is installed in step S100, and exposed and developed using a mask in steps S102 and S104 to the photoresist Form a circuit pattern. In step S106, portions other than the photoresist remaining on the circuit pattern portions are etched to remove unnecessary conductor layers. Subsequently, the remaining photoresist is peeled off corresponding to the circuit pattern in step S108 to obtain a conductor layer formed of the circuit pattern on the insulating layer.

In operation S110, image data of an ultrafine circuit pattern is acquired in pixel units to determine respective circuit patterns and spatial components, and an optical inspection is performed to detect the quality of the circuit pattern by measuring the respective widths. At the same time, in order to detect the opening or the short of the circuit pattern, the width of the circuit pattern or the space component is measured in the unit of pixels in the horizontal direction, and if the width of the measured circuit pattern is larger than the reference width, it is determined as defective. At this time, when the case where the width of the measured circuit pattern is larger than the reference width is not detected, the brightness level of each pixel is analyzed in the vertical direction to detect short or residual copper foil defects. In addition, open defects are detected by analyzing the brightness level in the vertical direction of the pattern component. A detailed detection process will be described in detail with reference to FIGS. 3 and 8.

After plating on the printed circuit board judged as good in step S112 and applying a solder resist in step S114, a final visual inspection is carried out in step S116.

Therefore, the method of manufacturing a flexible printed circuit board having an ultrafine circuit pattern according to the present invention improves parts that were not detected in the conventional optical inspection method, thereby detecting an open or short defect of the ultrafine circuit pattern in the optical inspection. The electrical inspection process for open or short detection of the process can be omitted. Therefore, the production cost can be reduced by reducing the manufacturing and inspection processes, and the yield can be improved and the competitiveness of the manufacturer can be improved by reducing the occurrence of defects.

In addition, this embodiment described a manufacturing method using an etching method for forming a very fine pattern, but in the manufacturing method using a plating method of forming a pattern by stacking the plating by the pattern thickness, the circuit pattern and the space component are formed. Obviously, optical inspection for open or short detection can be performed.

2 is a diagram illustrating a part of image data of a flexible printed circuit board according to the present invention.

Referring to FIG. 2, the image data 200 includes the first and second circuit patterns 210 and 230 of the ultrafine circuit patterns acquired in the pixel 202 unit, and the first and second circuit patterns 210 and 230. Space component 220 formed therebetween. In the present exemplary embodiment, the image data 200 includes the first and second circuit patterns 210 and 230 and the spatial component 220 disposed in the vertical direction.

Here, the fine patterns 240 and 250 formed in the spatial component 220 represent shorts to which the first and second circuit patterns 210 and 230 are connected, and the N columns and the N + 1 columns of the first circuit pattern 210. The portion 260 formed between the rows represents Open.

In this case, the optical inspection method of the present invention measures the width of the circuit patterns 210 and 230 in the pixel 202 unit in the horizontal direction in order to detect the short of the ultra fine circuit pattern. When the defects of the measured circuit patterns 210 and 230 are larger than the unit pixel size (216), for example, the measurement width of the first circuit pattern 210 is the spatial component 220 or / and the second circuit pattern ( 230 is present, it is an optically detectable short defect, so the reference width is compared with the widths 212 and 214 measured in the Nth column or the N + 1th column of the first circuit pattern 210. If larger (216) occurs, it is determined as a short (240).

However, when the pattern component is extremely fine and the measured width is smaller than the unit pixel size (250), a short formed between the pixel and the pixel cannot be detected by a general optical inspection. For example, since the short 250 formed between the first circuit pattern 210 and the second circuit pattern 230 is smaller than the unit pixel size and is a short formed between the pixel and the pixel, it is not detected by the general optical inspection. . Accordingly, in order to detect such a defect, the present invention is perpendicular to the width measuring direction of the first and second circuit patterns 210 and 230 among the pixels existing between the first and second circuit patterns 210 and 230. The brightness level of the pixels in the vertical direction is analyzed to determine a pixel portion having a lower brightness level than other portions as a short.

In addition, the optical inspection method of the present invention compares the brightness level of each pixel by measuring the brightness level of the pixels in the vertical direction in the direction of the circuit pattern (210, 230), in order to detect the opening of the ultra fine circuit pattern, If there is a pixel 260 larger than the brightness level of the pixels, it is detected as open.

Specifically, the optical inspection method for detecting the short and the residual copper foil of the ultrafine circuit pattern according to the present invention will be described using Figs.

3 is a flowchart illustrating an optical inspection procedure for short detection of an ultrafine circuit pattern according to an embodiment of the present invention. 4 and 5 are diagrams showing a pattern short between the ultrafine circuit patterns shown in FIG. 2, FIG. 6 is a waveform diagram showing a brightness profile measured in the vertical direction shown in FIG. 5, and FIG. A diagram showing copper foil remaining between ultrafine circuit patterns according to another embodiment of the present invention.

Referring to FIG. 3, in operation S120, image data 200 is acquired in units of pixels (202 of FIG. 2), and in operation S122, the circuit patterns 210 and 230 or the spatial components ( The width of 220 is measured to detect whether the circuit patterns 210 and 230 are positive or negative.

At this time, in order to detect the short of the ultra fine circuit pattern in step S124, it is determined whether the width of the measured circuit pattern is a defect larger than the reference width. As a result of the determination, if the measured width is a defect larger than the reference width, the procedure proceeds to step S126 to determine a pattern short (240 in FIG. 2). That is, the width measured by the first circuit pattern 210 extends over the short 240 existing on the spatial component 220 to the second circuit pattern 230 and is detected as a short.

However, if the measured width is smaller than the pixel size and is not detected in step S124 as shown in FIG. 4 and the defective shot 250 between the pixels, this procedure proceeds to step S128, in the vertical direction. The brightness level of the spatial component 220 is analyzed, and it is determined whether there is a part having a brightness level smaller than other pixels. That is, as shown in FIG. 5, the brightness levels of the two rows of pixels 226 which are the centers of the vertical direction of the spatial component 220 are measured, and the brightness levels of the other pixels among the brightness levels of the measured pixels are higher than those of the other pixels. Determine if there is a small area. That is, if there is a portion having a brightness level smaller than the spatial component 220, it is possible to determine that the short 250 exists.

As a result of the discrimination, if there is no portion smaller than the brightness levels of the other pixels, since the brightness level is similar to that of the spatial component 220, the procedure goes to step S130 to determine the pattern component well. In contrast, as shown in FIG. 6, if there is a region 302 smaller than the brightness levels of other pixels, the flow proceeds to step S132 to analyze the brightness levels of neighboring pixels of the region 302 having a small brightness level. That is, it is determined whether the brightness level of neighboring pixels is smaller than the brightness level of other pixels. This is for more accurate optical inspection, and compares neighboring rows with brightness levels of other pixels based on pixels in which data for a shot exists first, and checks the difference in brightness levels. In this way, when the brightness levels are sequentially checked in the vertical direction (274, 276 of FIG. 7), it is possible to know whether the short is connected or disconnected between the first circuit pattern 210 and the second circuit pattern 230, and a complete short. It is possible to determine whether it is 250 or the residual copper foil 270 shown in FIG. In the present invention, since the residual copper foil 270 may cause a short between the circuit pattern 210 and the circuit pattern 230, it is determined to be defective.

That is, if the result of the determination indicates that the brightness level of the neighboring pixels 274 and 276 is smaller than the brightness level of the other pixels, the procedure proceeds to step S136 to determine the pattern short 250 and to determine the neighboring pixels 274 and 276. If the brightness level of is similar to the brightness level of the spatial component 220, the flow advances to step S134 to determine the remaining copper foil 270.

8 to 10, the optical inspection method for detecting the opening of the ultrafine circuit pattern according to the present invention will be described.

That is, FIG. 8 is a flowchart illustrating an optical inspection procedure for open detection of an ultra fine circuit pattern according to an embodiment of the present invention, FIG. 9 is a view illustrating a pattern opening between the ultra fine circuit patterns shown in FIG. FIG. 10 is a waveform diagram illustrating a brightness profile measured in the vertical direction illustrated in FIG. 5.

Referring to FIG. 8, the open inspection method according to the present invention measures the brightness level of the circuit pattern 210 in the vertical direction in step S150. For example, as shown in FIG. 9, in order to detect an opening existing between pixels on the first circuit pattern 210, the direction perpendicular to the measurement direction for measuring the pattern width for each column of the first circuit pattern 210 is measured. In the row direction, for example, pixels 218 arranged vertically in the center row of the row direction of the first circuit pattern 210, that is, the three rows, are measured for each brightness level.

It is determined whether there is a part where the brightness level measured in step S152 is greater than the brightness levels of other pixels. For example, in order to detect an open existing between the pixels on the first circuit pattern 210, the deviation of the brightness level of each of the pixels arranged vertically of the first circuit pattern 210 is measured. When it is opened as in the case of short, about 50 levels of variation occur in the pattern component, and thus, the portion where the deviation occurs is opened.

That is, as a result of the determination, as shown in FIG. 10, if there is a portion 312 that is greater than the brightness level of the other pixels, the procedure proceeds to step S154 where the pattern is brightened by the open existing between the pixels. Is determined. If there is no portion larger than the reference brightness level, that is, the portion 314 having the brightness level similar to the circuit pattern between the pixels, the flow advances to step S156 to determine that the pattern is good.

In the above, the configuration and operation of the manufacturing method and the inspection method of the flexible printed circuit board having the ultra-fine circuit pattern according to the present invention is shown in accordance with the detailed description and drawings, but this is only described by way of example, the present invention Various changes and modifications are possible without departing from the technical spirit of the.

1 is a flowchart showing a manufacturing procedure of a printed circuit board for a display driving chip having an ultrafine circuit pattern according to the present invention;

2 is a diagram showing a configuration of image data acquired in units of pixels according to the present invention;

3 is a flowchart showing an optical inspection procedure for short detection of an ultrafine circuit pattern according to an embodiment of the present invention;

FIG. 4 is a diagram showing a pattern short between the ultrafine circuit patterns shown in FIG. 2; FIG.

FIG. 5 is a diagram for explaining short detection between the ultrafine circuit patterns shown in FIG. 4; FIG.

FIG. 6 is a waveform diagram illustrating a brightness profile measured in the vertical direction shown in FIG. 5; FIG.

7 is a view showing copper foil remaining between ultrafine circuit patterns according to another embodiment of the present invention;

8 is a flowchart showing an optical inspection procedure for open detection of an ultrafine circuit pattern according to an embodiment of the present invention;

9 is a view showing a pattern opening between the ultrafine circuit patterns shown in FIG. 2; And

FIG. 10 is a waveform diagram illustrating a brightness profile measured in the vertical direction illustrated in FIG. 5.

Explanation of symbols on the main parts of the drawings

200: image data 202: pixel

210: first circuit pattern 220: space component

230: second circuit pattern 240, 250: short

260: open 270: residual copper foil

300, 310: brightness profile

Claims (9)

In the inspection method of a flexible printed circuit board which detects the opening or short of a circuit pattern using an optical inspection, Obtaining image data of the flexible printed circuit board in pixel units; Measuring a width of a circuit pattern and a space component between the circuit patterns in a first direction perpendicular to a direction in which the circuit pattern is formed for each unit pixel in the image data; If it is detected that the measurement width is larger than the reference width, it is determined as a short; And If it is not detected that the measurement width is larger than the reference width, the brightness level is measured in a second direction perpendicular to the first direction, and if the measured brightness level is different from the ambient brightness level, it is determined to be defective. A method for inspecting a flexible printed circuit board. The method of claim 1, If it is not detected that the measurement width is larger than the reference width, the brightness level of the spatial component is measured in the second direction, and if there is a portion where the measured brightness level is smaller than the ambient brightness level, it is determined as a short. Inspection method of a flexible printed circuit board. The method of claim 2, Judging by the short, The brightness level is measured in the second direction with respect to the center pixel of the spatial component. If there is a pixel whose measured brightness level is smaller than the brightness levels of other pixels, the brightness level of the neighboring pixels of the pixel having the smaller brightness level is further measured, so that the brightness level of the neighboring pixels is smaller than the brightness level of the other pixels. Determine whether As a result of the determination, if the brightness level of the neighboring pixels is smaller than the brightness level of the other pixels, it is determined as a short. And if the brightness level of the neighboring pixels is not smaller than the brightness level of the other pixels, determining the remaining copper foil. The method according to any one of claims 1 to 3, The inspection method, Measure a brightness level of the circuit pattern in the second direction in the image data; Determine whether there is a region where the measured brightness level is greater than the ambient brightness level; And And determining that the measured brightness level is open when there are pixels whose measured brightness level is greater than the ambient brightness level. Forming an insulating layer on the base substrate; Installing copper foil on one side of the insulating layer; Applying a photo resist on the copper foil; Sequentially exposing, developing, etching, and peeling the substrate to form a circuit pattern; Optically inspecting an open or short state of the circuit pattern; And In the method of manufacturing a printed circuit board comprising the step of plating a substrate determined as good in the optical inspection, and applying a solder resist (solder resist), And after the step of applying the solder resist, a step of electrically inspecting the open or short state of the circuit pattern is omitted. The method of claim 5, wherein The optical inspection, A method of manufacturing a flexible printed circuit board, the open or short state having a smaller size than a unit pixel can be detected in the circuit pattern. The method of claim 5, wherein The optical inspection, Acquire image data of the flexible printed circuit board in pixel units, The width of the circuit pattern is measured for each unit pixel in the image data in a first direction perpendicular to a direction in which the circuit pattern is formed. And if it is determined that the measurement width for each unit pixel of the circuit pattern is larger than the reference width, it is determined as a short. The method of claim 7, wherein The optical inspection, If the measurement width for each unit pixel of the circuit pattern is not larger than the reference width, The brightness level of the pixels of the spatial component between the circuit patterns in the second direction perpendicular to the first direction is measured, and if there is a portion smaller than the other brightness level among the measured brightness levels, it is determined as a short. Flexible printed circuit board manufacturing method. The method according to any one of claims 5 to 8, The optical inspection, And measuring a brightness level of each pixel of the circuit pattern in the second direction, and determining that the measured brightness level is open if a portion of the measured brightness level is greater than another brightness level.

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