KR0152582B1 - Apparatus of automatically searching defect of no-pattern board and method of searching the same - Google Patents

Abstract

The present invention relates to a device for automatically detecting defects of a pattern-free substrate that does not have an electronic circuit pattern and that includes or does not include an electronic component insertion hole, a wiring via hole, a substrate fixing hole, and the like. Using an automatic retrieval device consisting of an independent single module searcher that does not require a computer for image processing, one or two long, thin linear light sources are irradiated onto the surface of the substrate, and then the reflected light from the surface is captured by the camera lens. Converting the image sensor array into an analog image signal; A second step of converting the analog image signal output from the CCD image sensor array into a digital signal through a video analog / digital converter and sending the analog image signal to a digital signal processing chip capable of processing the signal at high speed; By implementing an algorithm for processing a signal through a program and a data memory in the digital signal processing chip and displaying a search result detected by the display on the output display part, a defect of a patternless substrate is detected. It is possible to reduce manufacturing costs by eliminating the need for an image processing computer, to speed optical processing and real-time processing of optical imaging and signal processing by one-dimensional scanning, and to incorporate various digital signal processing chips. It has the advantage that the automatic detection of the type is easy. In addition, the single-module retrieval system consists of an optical imaging unit, a high-speed image signal processing unit, and an output display unit so that each functional unit can be easily adjusted according to the application. It is possible to implement a highly reliable, patternless defect detection system for automatically detecting a CCD (charge coupled device) sensor array having an imaging magnification and a variable number of sensors.

Description

Defect Automatic Detection Device of Patternless Substrate and Its Searching Method

1 is a block diagram schematically showing the structure of a single modular searcher for the automatic search of a patternless substrate according to an embodiment of the present invention.

FIG. 2 is a schematic view showing an automatic search apparatus to which the single modular searcher shown in FIG. 1 is applied.

3A to 3C are detailed conceptual views of an optical imaging method using a single light meter of the automatic retrieval apparatus shown in FIG.

4A to 4C are detailed conceptual diagrams of an optical imaging method using a mixed light system of the automatic retrieval apparatus shown in FIG.

* Explanation of symbols for main parts of the drawings

1: optical imaging unit 2: high speed image signal processing unit

3: Output display part 4: Auto search single module

5: light source 6a: camera lens

6b: CCD sensor array 7: Analog-to-digital converter (ADC)

8: High Speed Digital Signal Processing Electronic Circuit (DSPC)

9 LED display 10 CCD / ADC control circuit

11 program and data memory 12 boot ROM

13 LCD panel for display 14 Communication and display program unit

15a, 15b: linear light source 16: patternless electronic circuit board

17: transfer distance limit switch 18: motor controller for substrate transfer

19: substrate transfer motor 20: substrate transfer axis

S, S1, S2: Point light source PD: Point light source detector

A: Defective part B: Hole

C: flawless area

I (x): the intensity of reflected light along the X axis

V (x): CCD output signal in X axis direction

I ₁ (x): intensity of reflected light by point light source S1

I ₂ (x): intensity of reflected light by point light source S2

I ₁ (x) + I ₂ (x): Sum of reflected light I ₁ (x) and I ₂ (x)

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a device for automatically detecting defects of a patternless substrate and a method for searching the same, and in particular, does not include an electronic circuit pattern, and includes or does not include holes for inserting electronic components, wiring via holes, substrate fixing holes, or the like. Scratch defects or dent defects on a patternless substrate can be automatically detected and measured without the use of a separate computer. An automatic search apparatus and a search method using the same.

Recently, there is a great demand for the development of a single modular searcher capable of automatically searching for defects of a board at high speed without an operator due to the increase in complexity and demand of the board.

In order to perform such an automatic search, a method that has been mainly used in the past has been performed by scanning a predetermined area by a two-dimensional CCD (charge-coupled device) image sensor array to obtain a two-dimensional image, and then performing high-speed signal processing. Image processing can be done by storing them on expensive computers as much as possible.

However, when the defects of the patternless substrate are automatically detected using the above method, it is difficult to process a large amount of image data at high speed while achieving accurate synchronization between the scanned image and the image and low cost of the equipment. .

Accordingly, the present invention was made to improve the above-mentioned disadvantages, and the optical imaging and signal processing by one-dimensional scanning and the high speed and real-time processing are possible as well as the automatic detection of various types of defects without a separate image processing computer. It is an object of the present invention to provide an automatic defect detecting apparatus for a patternless substrate and a searching method thereof.

In order to achieve the above object, the defect automatic detection apparatus of a patternless substrate according to an embodiment of the present invention includes a substrate transfer unit for transferring a patternless substrate using a substrate transfer motor within a range of a transfer distance limit switch; ; An optical imaging unit arranged on an upper side of the substrate transfer unit on which a pattern-free substrate is placed and configured to convert a beam irradiated from a linear light source into an image signal, comprising a camera lens and a one-dimensional CCD image sensor array; Characterized in that it consists of a single modular searcher arranged on one side of the optical image unit.

According to another aspect of the present invention, there is provided an apparatus for automatically detecting defects of a patternless substrate, comprising: an optical image unit configured to convert a beam irradiated from a light source into an image signal by using a camera lens and a 1D CCD image sensor array; ; Detects defects on a patternless substrate by implementing analog and digital converters for converting image signals extracted from the 1D CCD image sensor array into digital signals, and processing desired digital signals at high speed through programs and data memories. A digital signal processing chip; A high speed image signal processor comprising a boot ROM for booting the digital signal processing chip, and a light emitting diode display for dividing the searched area into several sections to identify which section is defective; It consists of a liquid crystal display panel for displaying the search results and a communication and display program unit, characterized in that the display unit for displaying the overall search results received from the high-speed image signal processing unit using the liquid crystal display panel.

On the other hand, the search method using a defect automatic detection device of a patternless substrate according to an embodiment of the present invention for achieving the above object by irradiating a beam on the surface of the substrate with one or two long and thin linear light source on the surface of the substrate Converting the reflected light into an analog image signal in the one-dimensional CCD image sensor array by a camera lens; A second step of converting the analog image signal output from the CCD image sensor array into a digital signal through a video analog / digital converter and sending the analog image signal to a digital signal processing chip capable of processing the signal at high speed; And a third step of implementing an algorithm for processing a signal through a program and a data memory in the digital signal processing chip and displaying the search result detected on the output display.

By configuring and operating the automatic searching device as described above, it is possible to automatically search for defects of the patternless substrate without a separate image processing computer.

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

FIG. 1 illustrates a schematic configuration of a single module type searcher for the automatic search of a patternless substrate by function, and the defect automatic search apparatus and the searching method of the patternless substrate will be described in detail with reference to the following. .

As can be seen from the above figure, the internal configuration of the single module 4 of the single module searcher for automatic defect detection according to the present invention includes the one-dimensional CCD image sensor arrays 6a and 6b, the high speed image signal processor 2, and the result. Is composed of an output display unit (3) showing an optical display unit (1) for imaging a substrate (16), a high speed image signal processing unit (2), and an output showing a result. It is divided into three parts of the display part 3.

At this time, the optical image unit 1 illuminates the substrate 16 by using a long and thin halogen lamp or fluorescent lamp as the light source 5, and the reflected light emitted from the substrate by the camera lens 6a is a linear one-dimensional CCD image sensor. It is configured to be accurately imaged in the array (6b). Accordingly, the surface of the substrate 16 is imaged by the camera lens 6a and the one-dimensional CCD image sensor array 6b, and the image sensor array 6b extracts the one-dimensional analog image signal as an output signal to the surface of the substrate. do.

The high speed image signal processor 2 converts the analog image signal extracted from the CCD image sensor array 6b into a digital signal through an analog / digital converter (hereinafter, referred to as an ADC) 7. A digital signal processing chip (hereinafter referred to as DSPC) booted by a booting ROM 12 to detect a defect by implementing a desired algorithm while processing the digitalized signal at high speed ( 8). The DSPC 8 receives a digital signal from the ADC 7 and performs a search algorithm stored in the program memory 11. At this time, the processed result is stored in the data memory 11, and the search result by interaction with the DSPC 8 is sent to the output display unit 3 using a liquid crystal display panel 13 or the like. . The light emitting diode (LED) display 9 divides the searched area into several sections to visually identify which section is defective.

The output display unit 3 receives a search result for each scanned linear region received by the high speed image signal processing unit 2 by the communication 14, and numerically receives the search results collectively according to the purpose of determining the substrate state. The display result is displayed on the LCD panel 13 for display via the display program unit 14 for viewing.

A method of automatically searching the patternless substrate 16 at high speed using a single modular searcher composed of the above components is as follows.

First, as a first step, when the surface of the substrate 16 is illuminated with a long thin linear light source, the reflected light on the surface is converted into a video signal in the one-dimensional CCD image sensor array 6b by the camera lens 6a.

Thereafter, as a second step, an analog electric signal output from the CCD image sensor array 6b is converted into a digital signal through the video ADC 7 of the high speed image signal processing unit 2 and then processed at high speed. Is sent to (8).

Subsequently, as a third step, the DSPC 8 implements an algorithm for processing signals through a program and a data memory 11 and sends the detected signal to the output display unit 3 without using a computer. You can automate the search.

On the other hand, Figure 2 is a schematic diagram showing a schematic diagram of the automatic search device is applied to the single modular searcher shown in Figure 1, as can be seen in the automatic search device range of the travel distance limit switch 17 A substrate transfer portion for transferring the patternless substrate 16 using the substrate transfer motor 19 therein, and an upper side of the substrate transfer portion on which the patternless substrate 16 is placed, the camera lens 6a and It consists of a one-dimensional CCD image sensor array (6b) consists of an optical imaging unit (1) for converting a beam irradiated from a linear light source into an image signal, and a single modular searcher (4) arranged on one side of the optical imaging unit (1) Long and thin linear light source when the patternless substrate 16 including the linear defect L and the hole H is transported or stopped to the transport motor 19 within the range of the travel distance limit switch 17. Linear light emitted from 15a and 15b causes the substrate 16 to It is supposed to illuminate.

Therefore, when the linear light illuminates the substrate 16, the light reflected from the surface of the substrate 16 is focused on the one-dimensional CCD sensor array 6b by the camera lens 6a, and inside the single module 4 Is processed by the high speed video signal processing unit 2.

As the linear photodetector for the single module 4, a CCD image sensor array 6b in which a large number of sensors are arranged is used, and a signal output from the CCD sensor 6b is applied to an offset voltage of the sensor. The strongly input light is converted into a low voltage, and the weakly input light approaches the offset voltage to output a signal inverted with respect to the intensity of the reflected light. Therefore, the level of the CCD output signal obtained from a portion free from defects or holes is minimized, and the output signal level is maximized at a portion without reflection, such as a large hole, where all light passes.

This inverted analog signal is converted into an 8-bit digital signal through the ADC 7, and the intensity of the beam reflected from the substrate has 256 digital level values.

At this time, if 100% of the reflection is made on the complete reflection surface, if there is no reflection like the center of the large hole, it is displayed as 255. In the defective part, the value is between 0 and 255 due to diffuse reflection or the like.

3 (a) to 3 (c) show an optical imaging method using a single lighting system of the automatic retrieval apparatus shown in FIG. 2 and a detailed conceptual diagram of the image signal thereof, with reference to the drawings. The principle of imaging is as follows.

FIG. 3 (a) shows an optical imaging method using a single light meter of the automatic retrieval apparatus. In this figure, a point light source S and a point light source detector PD of the linear light source 15a are formed on the substrate surface. When imaging the surface of the substrate while moving from A to B while being symmetrical with respect to the normal line, the incident beam is brightly reflected at the same angle of incidence with respect to the normal line at the C position without defect.

On the other hand, when comparing the intensity (I _x ) of the reflected light along the X-axis direction, as shown in FIG. 3 (b), the intensity of light entering the point light source detector by the diffuse reflection is reduced at the defective A position, In the B position with the hole, the reflected light intensity has the highest value.

FIG. 3 (c) shows the inverted signal of the reflected light shown in FIG. 3 (b) and shows the output signal level in the X-axis direction obtained from the CCD image sensor array.

As shown in Fig. 3 (c), when the width of the signal obtained from the defect is much smaller than the minimum diameter of the holes of various sizes included in the unpatterned substrate, the signal in the X-axis direction of the detected signal is Defects can be detected by comparing the widths or by calculating p (= h / w), which is the ratio of the height h to the signal width W in the X-axis direction. This is because the value of p obtained from the defect is relatively larger than the value of p obtained from the via hole or the insertion hole of the electronic component, so that only the defect can be easily distinguished.

In this case, since the amplitude of the defect signal is smaller than that of the hall signal, and the width of the defect signal is much smaller than the width of the hall signal, the defect is obtained even if r = 1 / (h * w), which is the inverse of the product of the two widths, is obtained. Only r can be extracted. In this case, the r value increases in the case of a defect, and the r value decreases in the case of a hole.

On the other hand, in the case of a patternless substrate without holes, the signal a having a large amplitude shown in FIGS. 3B and 3C does not appear, and only a signal due to a defect is obtained. In such a case, defect detection can be facilitated by preselecting a threshold value for a signal amplitude according to a threshold value for a width of a defect to be detected or a desired characteristic, and extracting only a signal having a value equal to or greater than this threshold value. In this case, the threshold may be an average value of the detected one-dimensional signal or a value modified thereto.

4 (a) to 4 (c) show an optical imaging method using a mixed light intensity of the automatic retrieval apparatus shown in FIG. 2 and a detailed conceptual diagram of the video signal. Referring to FIG. The principle of imaging is as follows.

FIG. 4 (a) shows a method of imaging the substrate surface by using one more linear light source 15b on the opposite side of the substrate 16 to suppress the influence of the holes. In FIG. As shown, the point light source S1 from the linear light source 15a on the top of the substrate 16, the point light source S2 from the linear light source 15b on the bottom, and the point light source detector PD of the linear light detector 6b. When the light moves from left to right together, the intensity I ₁ of the reflected light by the point light source S1 appears as shown in FIG. 4 (b), and the intensity I ₂ of the reflected light by the point light source S2. Appears as shown in FIG. Therefore, when the sum of the intensities of the reflected light by the point light source (S1) and the point light source (S2) it is possible to obtain the intensity (I ₁ + I ₂ ) of the reflected light as shown in FIG.

That is, in the part where the hole is present, since the point light source S2 is directly input to the point light source detector PD, the influence of the image signal of the hole generated by the point light source S1 can be suppressed, so that the defect is as shown in FIG. Only the signal corresponding to the will be obtained.

As a result, defect detection is a case of searching for a board without holes, and automatic detection of defects is easy by selecting an appropriate threshold value according to the average value of the image signal obtained from one line of the scanned substrate or the state of the substrate. Done.

As described above, the present invention eliminates the need for a separate image processing computer, thereby reducing manufacturing costs, and enables optical imaging and signal processing to be accelerated and real-time by one-dimensional scanning, and digital signal processing. The built-in chip (digital signal processing chip) has the advantage of easy automatic detection of various defect types.

In addition, since a single module search system is composed of an optical imaging unit, a high-speed image signal processing unit, and an output display unit, each functional unit can be easily adjusted according to the application, and according to the size of the substrate and the size of the defect to be detected, This has the advantage of easily changing the charge coupled device (CCD) sensor array with imaging magnification and variable number of sensors.

Claims (6)

A substrate transfer unit for transferring a patternless substrate using a substrate transfer motor within a range of a transfer distance limit switch; An optical image unit arranged on an upper side of the substrate transfer unit on which a pattern-free substrate is placed, and including a camera lens and a one-dimensional CCD image sensor array to convert a beam irradiated from a linear light source into an image signal; Defect automatic detection device of a patternless substrate, characterized in that consisting of a single modular searcher arranged on one side of the optical image unit. The apparatus of claim 1, wherein the linear light source comprises any one selected from a long and thin halogen lamp or a fluorescent lamp. The apparatus of claim 1, wherein the single module type searcher comprises: an imaging unit using a 1D CCD image sensor array; Detects defects on a patternless substrate by implementing analog and digital converters for converting image signals extracted from the 1D CCD image sensor array into digital signals, and processing desired digital signals at high speed through programs and data memories. A high speed image signal processing unit comprising a digital signal processing chip, a boot ROM for booting the digital signal processing chip, and a light emitting diode display for dividing the searched area into several sections to identify which section is defective; LCD display panel for displaying the search results and communication and display program unit consisting of an output display unit for displaying the overall search results received from the high-speed image signal processing unit using the liquid crystal display panel automatic detection of defects on a patternless substrate Device. An optical imaging unit comprising a camera lens and a one-dimensional CCD image sensor array for converting the beam irradiated from the light source into an image signal; Detects defects on a patternless substrate by implementing analog and digital converters for converting image signals extracted from the 1D CCD image sensor array into digital signals, and processing desired digital signals at high speed through programs and data memories. A digital signal processing chip; A high speed image signal processing unit including a boot ROM for booting the digital signal processing chip, and a light emitting diode display for dividing the searched area into several sections to identify which section is defective; 2. An apparatus for automatically detecting defects of a patternless substrate, comprising: an output display unit comprising a liquid crystal display panel and a display and communication unit; A first step of irradiating a beam on the surface of the substrate with one or two long thin light sources to convert the reflected light from the surface of the substrate into an analog image signal in the one-dimensional CCD image sensor array; A second step of converting the analog image signal output from the CCD image sensor array into a digital signal through a video analog / digital converter and sending the analog image signal to a digital signal processing chip capable of processing the signal at high speed; And a third step of implementing an algorithm for processing a signal through a program and a data memory in the digital signal processing chip, and displaying the search result detected on the output display unit. Search method using device. The method of claim 5, wherein the first step is to irradiate a beam to the substrate using a linear light source arranged on the top of the substrate when irradiating a beam to the surface of the substrate with one linear light source to perform automatic detection of defects of the patternless substrate. In the case where automatic detection of defects of a patternless substrate is performed by irradiating a beam to the surface of the substrate with two linear light sources, the beam is simultaneously irradiated to the substrate with the linear light sources arranged at the top and bottom of the substrate. Retrieval method using defect automatic detection device of pattern board.