KR100722608B1 - Inspection method of Printed Circuit Board - Google Patents

Abstract

The present invention relates to a method for inspecting a printed circuit board, and more particularly, to detect minute defects occurring in a printed circuit board, and to inspect the piezoelectric ceramic material on a fill plated printed circuit board. When the board is placed and the pressure is applied to the test board using a suspan, voltage is generated. The voltage generated from the test board is output as the voltage amount per position coordinate of the printed circuit board, and then the printed circuit is used by using the output voltage value. Fine defects on the surface of the substrate can be found.

Printed Circuit Board, Inspection Device, Piezoceramic Device, Defective Determination Unit, Image Generator

Description

Inspection method of printed circuit board {Inspection method of Printed Circuit Board}

1 is a schematic configuration diagram of an AOI device of a conventional printed circuit board;

2 is a flow chart for checking whether a conventional printed circuit board is defective;

3A to 3C are side views showing good and defective products in a peeled state of a printed circuit board;

4 is a schematic configuration diagram of an inspection apparatus used in the inspection method of a printed circuit board according to an embodiment of the present invention; And

5 is a flowchart for checking whether a printed circuit board is defective according to an embodiment of the present invention.

<Description of Symbols for Major Parts of Drawings>

210: printed circuit board 212: dimple or unfilled

220: test substrate 222: cylinder

230: suspan 240: voltage output unit

250: video generation unit 260: bad judgment

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a printed circuit board, and more particularly, to a method for inspecting a printed circuit board for detecting minute defects occurring on a surface of a fill plated printed circuit board.

In general, the inspection method of a printed circuit board is realized by an automatic optical inspection (AOI) method using an image pickup device (Charge Coupled Device, CCD) camera in the form of a wiring pattern on the surface of the printed circuit board. The AOI method is an apparatus that automatically inspects the external appearance of a circuit using an image sensor and a computer's pattern recognition technology, and reads pattern information of an inspection target circuit into an image sensor and compares it with reference data to read out defects.

1 is a schematic configuration diagram of a conventional AOI device for a printed circuit board. Looking at the conventional AOI device 100 with reference to Figure 1 as follows.

The conventional AOI device 100 is equipped with an infrared lamp 120 as a light source on one side of the upper portion of the printed circuit board 110, the lens 130 is spaced apart from the upper portion of the printed circuit board 110, the lens The CCD camera 140 is installed on the 130, wherein the infrared rays emitted from the lamp 120 are projected onto the printed circuit board 110 and reflected and input to the CCD camera 140 via the lens 130. .

In addition, the CCD camera 140 is connected to the image processing unit 150 for converting the input infrared brightness into an image, and the image processing unit 150 is connected to the defect determining unit 160 for determining a defect using the converted image. do.

In general, the infrared rays projected onto the printed circuit board are brightly displayed in the image processing unit by specular reflection in the wiring pattern part, and are darkly displayed in the image processing unit because the infrared reflection is diffusely reflected in the reinforcing material such as an insulator. Therefore, the defective judging unit 160 compares the input reference data with previously input image data to determine a defective circuit.

2 is a flowchart for checking whether a printed circuit board is defective using a conventional AOI device.

Conventional inspection method includes the step of projecting the infrared ray to the printed circuit board 180; A step 182 in which infrared rays projected onto the printed circuit board are reflected and inputted to the CCD camera to be converted into data; Generating an image corresponding to the surface of the printed circuit board by the image processor using the converted data (184); In the bad judgment unit, a step 186 of determining whether or not a defect is performed using an image is included.

At this time, in the step 186 of determining whether the defect is good or not, the circuit state of the surface of the printed circuit board is determined as good 186 or bad 188 by comparing the imaged data with the reference data.

In the conventional method of inspecting a printed circuit board using the AOI inspection apparatus, since light is used to recognize a defect in a circuit, there is a problem in that a defect such as a dimple or a fine pencil exhibiting a small light intensity difference cannot be found.

In more detail, the dimple or the unfilled, in the case of fill plating the hole of the printed circuit board, as shown in Figure 3a, the surface and the hole of the printed circuit board should be plated flat. However, as shown in FIG. 3B, the difference in height between the surface of the printed circuit board and the holes may be, for example, dimples of 25 μm or more, and the height of the surface of the printed circuit board and the holes may be as shown in FIG. 3C. The difference may be, for example, unfilled particles of 50 µm or more.

Thus, although described above, the AOI device can determine the circuit with the AOI device due to the reflection different from the reflection of the insulator and the pattern, but the dimples or the mifills appearing in the pattern part are plated with the same material as the normal pattern and use light. When the dimple, the pill and the good product (normal pattern) are all specular reflection occurs in the AOI device that checks whether the pattern is formed, there was a problem that can not know whether the defects such as unfilled or dimple.

The present invention has been made to solve the above-mentioned problems of the prior art, the direct amount of voltage generated by the pressure by directly contacting the test substrate using a piezoelectric ceramic element and the like to the printed circuit board only up to the peel plating and pressurizing the surface It is to provide a method for inspecting a printed circuit board that can determine whether the peeled portion of the printed circuit board is defective by using the result value.

In order to achieve the above object, the present invention provides (A) an inspection substrate composed of grid-shaped units, a voltage output unit for receiving signals generated from individual units, and an image output corresponding to the units from the voltage output unit. Preparing an inspection apparatus including an image generation unit for generating a and a defect determination unit for checking an image of the image generation unit for each unit and determining whether the image corresponds to an individual unit; (B) placing the test substrate onto the surface of the fill plated printed circuit board; (C) pressing the entire test substrate with equal pressure; (D) transferring the voltage generated in the individual units by the pressure to the voltage output unit; (E) generating an image corresponding to the surface of the printed circuit board by using the voltage value of each unit in the image generating unit; And (F) in the defective judging unit, determining whether or not the defective plating portion of the printed circuit board corresponding to the unit is defective by using the image. Wherein each of the units is a piezo eletric ceramic device for converting pressure into voltage.

In the present invention, in step (A), the printed circuit board has a fill plated via hole, and each unit is manufactured to a size corresponding to the fill plated via hole.

In addition, in the present invention, in the step (C) using a suspan to pressurize the test substrate is characterized in that a plurality of cylinders are installed with a predetermined position on the upper surface of the test substrate.

In addition, in the present invention, the voltage generated in each unit pressurized in step (D) is characterized in that it is output as the amount of voltage per position coordinate of the printed circuit board.

EMBODIMENT OF THE INVENTION Hereinafter, preferred embodiment of this invention is described with reference to an accompanying drawing.

4 is a schematic configuration diagram of an inspection apparatus 200 used in an inspection method of a printed circuit board according to an exemplary embodiment of the present disclosure.

In the inspection apparatus 200 of the present invention, the printed circuit board 210 is fill plated to perform inspection while the surface of the printed circuit board 210 is flat, where the fill plated state is a multilayer having a via hole. By electroless plating and electrolytic copper plating on the printed circuit board 210, the via hole is filled with copper plating.

The inspection board 220, which is composed of grid-shaped units, may be spaced apart from the top of the printed circuit board 210 which is fill-plated to descend to the surface of the printed circuit board 210. On the upper part of the test substrate 220 is placed a suspan 230 for applying pressure to the test substrate 220, a plurality of in order to check whether the pressure is uniformly applied to the entire test substrate 220 It is preferable that the cylinder 222 has a predetermined position and is installed between the test substrate 220 and the suspend plate 230.

In addition, the test substrate 220 that is pressured by the suspan plate 230 is connected to the voltage output unit 240 that outputs the voltage generated by the pressure of the test substrate 220, the voltage output unit 240 is It is connected to the image generating unit 250 for generating an image using a voltage value, the image generating unit 250 is a defect that determines whether or not defective, such as unfilled or dimples on the peeling portion of the printed circuit board 210 It is connected to the determination unit 260.

In addition, the test substrate 220 may be made of a piezoelectric ceramic (piezo electric ceramic) element for converting the pressure into a voltage, the suspension plate 230 may be made of stainless, the test substrate 220 Individual units are preferably manufactured in sizes corresponding to fill plated via holes (not shown).

In addition, the image generating unit 250 generates an image corresponding to the amount of voltage generated by the pressure between the test substrate 220 and the surface of the printed circuit board 210, in this image if the dimple in the hole If a defect 212, such as or unfilled, is generated, the image is generated to reduce the amount of voltage in the region. Therefore, the defective decision unit 260 determines the defects such as dimples and unfilled surfaces of the printed circuit board 210 with the generated image data.

Next, FIG. 5 is a flowchart for checking whether a printed circuit board is defective according to an embodiment of the present invention.

The test method of the present invention can be performed through the following steps. First, the inspection substrate is disposed on the surface of the printed circuit board which is fill plating (280). Example The test substrate is preferably composed of units in the form of a lattice and the units each comprise a piezoceramic element.

Next, the pressure is equally applied to the entire test substrate (282). Pressure is applied to the entirety of the test substrate by using a suspan, and it is preferable that a cylinder is installed on the upper surface of the test substrate in order to confirm application of uniform pressure to the entire test substrate.

Next, the test board pressurized by the suspan is brought into contact with the surface of the printed circuit board, and the voltage generated by the contact pressure is transmitted to the voltage output unit for each unit (284). The image generating unit generates an image corresponding to the surface of the printed circuit board using the voltage value (286), and the bad judgment unit uses the image generated by the image generating unit to fill the plated portion of the printed circuit board corresponding to each unit. It is determined whether or not the failure for (288).

In addition, in step 286 of generating an image, the voltage generated from the test substrate (see FIG. 4 and 220) is output as a voltage amount per position coordinate of the printed circuit board (see FIG. 4 and 210). In the step 288 of determining whether the fill plating part is defective, the state of the surface of the printed circuit board may be determined as good 290 and bad 292 depending on whether the output voltage value is constant or decreased.

As described above, in the present invention, the fii palting printed circuit board is in direct contact with the inspection substrate including units composed of a lattice-like piezoceramic element, so that the inspection substrate is based on individual units. The voltage is generated according to the applied pressure, and defects such as unfilled or dimples on the peeled portions of the printed circuit board may be measured using an image of the generated voltage.

According to the inspection method of the printed circuit board of the present invention, an inspection substrate formed of units such as piezoceramic elements is directly in contact with the surface of the printed circuit board, which has undergone peel plating, and according to the pressure of the inspection substrate, Since the voltage is generated in each unit and the amount of voltage generated therefrom can be measured, it is possible to determine whether there is a defect such as an unfilled or dimple in the peeling portion of the printed circuit board.

Claims (5)

(A) preparing a test substrate composed of grid-shaped units; (B) placing the test substrate on the surface of the fill plated printed circuit board; (C) pressing the entire test substrate at an equal pressure; (D) measuring the voltage generated in the individual units by said pressure; (E) generating an image corresponding to the surface of the printed circuit board using the measured voltage value; And (F) determining whether the fill plating portion of the printed circuit board corresponding to the individual units is defective by using the generated image; Wherein each of the units is a piezoelectric ceramic element for converting pressure into voltage. The method of claim 1, wherein in the step (B), the printed circuit board has a fill plated via hole, and each unit is manufactured to have a size corresponding to the fill plated via hole. The method of claim 1, wherein in the step (C), the test substrate is evenly pressed using a suspan. The method of claim 1, wherein the voltage generated in each unit pressurized in the step (D) is output as an amount of voltage per position coordinate of the printed circuit board. The method of claim 1, wherein the inspection method is performed using an inspection apparatus including the inspection substrate, wherein the inspection apparatus: A voltage output unit which measures a voltage generated from the individual units during pressurization; An image generator configured to generate an image output corresponding to each unit by using the measured voltage; And A defect determination unit which checks the image of the image generating unit for each unit and determines whether there is a defect corresponding to an individual unit; Printed circuit board inspection method comprising a further.

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