KR100289441B1 - Method for examining hole of printed circuit board - Google Patents

Abstract

PURPOSE: A method for examining a hole of a printed circuit board is provided to obtain a hole position and size information from CAD data and examine only a necessary part in real time at a high speed. CONSTITUTION: CAD data are analyzed and reference hole data are gathered(ST101-ST102). An image of a PCB which is examined is obtained by using an image acquiring device(ST103). An actual hole is searched in an image obtained in the ST103 with reference to the reference hole data(ST105). A radius of a reference hole obtained from the ST101-ST102 and a radius of an actual hole obtained from the ST105 are compared with each other and whether the actual hole is defective is determined(ST106). Border portions of a circle in diverse directions from the center of the actual hole obtained from the ST105 are examined and whether the actual hole is defective is determined according to a comparison result of the reference hole land width and an actual hole land width(ST107).

Description

Hole inspection method of printed circuit board

The present invention relates to a hole inspection method of a printed circuit board (hereinafter referred to as "PCB"), in particular to inspect the hole of the PCB using image processing, but the position and size information of the hole from the CAD data The present invention relates to a method for inspecting a hole in a PCB that allows only a necessary part to be inspected at high speed in real time.

1 is a view for explaining various defects that may occur in the hole of the PCB.

(a) is the outline of the reference hole having a normal land width (A), (b) is a defect hole having a narrow abnormal land width (A ') compared to the reference hole shown in (a). , (c) is a defective hole having an eccentric amount B due to an incorrect position of the hole compared to the reference hole shown in (a). At this time, (b) and (c) are called a hole defect.

A conventional hole inspection method for detecting such hole defects is described with reference to FIG. 2 as follows.

First, in the first step, the entire image of the PCB is processed to find the boundary between the outer circle 1 and the inner circle 2 of the hole while reading the value of each pixel.

In the second step, the trajectory of the outer circle 1 is obtained to obtain the center and the size, and in the third step, the center and the size of the inner circle 2 are obtained.

However, conventionally, as well as searching the entire image as described above, as shown in FIG. 2 (b), if there is a pattern 4 or the like besides the background 3, the algorithm for determining whether or not the hole is complicated This necessitated a problem that the test time was excessively required.

Therefore, the present invention has been proposed to solve the above problems of the prior art, to inspect the flow of the PCB using the image processing, but to obtain the position and size information of the hole from the CAD (CAD) data to inspect only the required portion in real time at high speed Its purpose is to provide a hole inspection method for a PCB.

In order to achieve the above object, the hole inspection method of the circuit board of the present invention, the first step of analyzing the CAD data to create the reference hole data, and using the image acquisition device to obtain an image of the inspection target printed circuit board The second step,

A third step of finding an actual hole in the image obtained in the second step by referring to the reference hole data obtained in the first step;

A fourth step of determining whether the actual hole is defective by comparing the radius of the reference hole obtained in the first step with the radius of the actual hole obtained in the third step;

And a fifth step of determining whether or not the actual hole is defective according to a comparison result of the reference hole land width and the actual hole land width by examining the boundary of the circle in various directions from the center of the actual hole obtained in the third step. It is done.

1 is a view for explaining various defects that may occur in a hole of a printed circuit board.

2 is a view for explaining a hole inspection method of a conventional printed circuit board.

3 is a flowchart for explaining a hole inspection method of a printed circuit board according to the present invention.

4 is a view showing reference hole data obtained according to the hole inspection method according to the present invention and image acquisition data of actual holes.

5 and 6 are reference drawings for explaining the hole inspection method according to the present invention.

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

3 is a flowchart for performing a hole inspection method of a PCB according to the present invention, the first step (ST101 ~ ST102) of analyzing the CAD data to create the reference hole data and the inspection target using the image acquisition device A third step (ST103) of acquiring an image of the PCB, and a third step of finding an actual hole in the image obtained in the second step (ST103) with reference to the reference hole data obtained in the sieve steps (ST101 to ST102). A fourth step (ST106) for comparing the radius of the reference hole obtained in the first steps ST101 to ST102 with the radius of the actual hole obtained in the third step ST105 to determine whether or not the actual hole is defective; A fifth step of determining whether the actual hole is defective according to a comparison result of the reference hole land width and the actual hole land width by inspecting a boundary portion of the circle in various directions from the center of the actual hole obtained in the third step ST105; Made up (ST107).

Referring to Figures 3 to 6 attached to the operation and effect of the present invention configured as described above are as follows.

First, we analyze the Gerber files, which are one of the standardized output formats that can be obtained after designing a PCB with CAD, and tool data, ie CAD data, indicating the size (diameter) of the tool (e.g. drill). To create the reference hole data. (ST101-ST102)

An example of the gerber file and tool data is shown below.

<Hall Gerber File>

<Tool data>

Here, D10 * X10790Y5682 refers to a process of analyzing that a hole is drilled by a tool of D10, that is, a tool having a size of 0.012 inch (for example, a drill) at X and Y coordinates (10790,5682).

Through this analysis, reference hole data shown in FIG. 4 (a) is generated, but only the hole to be inspected among the plurality of holes on the PCB is converted into reference hole data.

Next, an image of the PCB is obtained by using an existing image acquisition device. (ST103)

Thereafter, the actual hole shown in FIG. 4 (b) is found with reference to the reference hole data of FIG. 4 (a) obtained in step ST102. (ST105)

That is, as shown in FIG. 5 (a), the boundary between the hole and the background is found in the eight directions from the reference holes Vx and Vy where the position is known, and eight boundary points <X (0) and Y (0)> are found. , <X (1), Y (1)>, ..., <X (n), Y (n)>, and from this, the known hole of the actual hole shown in Find the center (Cx, Cy) and the radius (r ').

In step ST102, the radius r of the reference hole, which is already known, is compared with the radius r 'of the actual hole obtained in step ST105, to determine whether the actual hole is defective. (ST106)

For example, when a reference value, which is a criterion, is T, | If r -r '| ≤ T, it is determined as normal, and | r -r '| If T, it is determined as bad.

Next, the hole specification is examined by examining the boundary of the circle in eight directions from the centers Cx and Cy of the holes obtained in step ST105. (ST107)

At this time, the acceptance judgment checks whether all of the periphery of the hole satisfies the normal land width A as shown in FIG. 6 (a), or as shown in FIG. 6 (b), the minimum land width A ″. ), And check if it is larger than the normal land width (A).

Only the holes judged to be normal in both ST106 and ST107 through the steps ST101 to ST107 are determined to be normal, and if any of the steps is defective, the defect is treated as a defect. (ST108)

On the other hand, by repeating the above-described series of steps ST105 to ST108 the same number of times as the number of holes (N) on the PCB to determine whether all the holes on the PCB are defective (ST109, ST104 ~ S108).

As described above, the present invention obtains the position and size information of the hole from CAD data and inspects only the required portion at high speed, thereby satisfying the inspection speed of the real-time inspection system and selecting the data when making reference hole data. It is possible to register the hole to be inspected and the hole to not be inspected among a plurality of holes on the top of the box, and it is also applicable to the case where the object to be inspected is not a hole but a rectangle or other shape.

Claims (2)

Analyzing the CAD data to create reference hole data; acquiring an image of an inspection target printed circuit board using an image acquisition device; and acquiring the image by referring to reference hole data obtained through the creation of the reference hole data. In the hole inspection method of a printed circuit board comprising the step of finding the actual hole in the image obtained in the step, the hole inspection method of the printed circuit board, a plurality of holes on the inspection target printed circuit board in the reference hole data creation step Only the holes to be examined are converted into reference hole data, and the actual hole is found in the image obtained in the image obtaining step by referring to the reference hole data, and the radius of the reference hole obtained in the reference hole data creating step and the actual hole are Compare the radius of the actual hole obtained through the finding step to find the Determining the wealth and determining whether the actual hole is defective according to a comparison result of the reference hole land width and the actual hole land width by examining the boundary of the circle in various directions from the center of the actual hole obtained in the step of finding the actual hole. Hole inspection method of a printed circuit board, characterized in that consisting of. The printed circuit of claim 1, wherein, in the determining whether the actual hole is defective, a test is performed to determine whether all of the periphery of the actual hole satisfies the normal land width or to obtain a minimum land width of the actual hole and then compare the result with the normal land width. Hole inspection method of the board.

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