KR19990057556A - Hole inspection method of printed circuit board - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hole inspection method of a printed circuit board (PCB), wherein the hole of the printed circuit board (PCB) is inspected using image processing, and the position and size information of the hole are obtained from the CAD data, and only the necessary portions are examined. By satisfying the inspection speed of the real-time inspection system and selecting it when making reference hole data, it is possible to register the hole to be inspected and the hole not to be inspected among a plurality of holes on the PCB. In the case of a square or other shape is also applicable.

Description

Hole inspection method of printed circuit board

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hole inspection method of a printed circuit board (hereinafter, referred to as a "PCB"). In particular, the hole of the PCB is inspected using image processing, and the position and size information of the hole is determined from CAD data. The present invention relates to a method of 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 referred to as hole defects.

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, in the related art, in addition to searching the entire image as described above, as shown in FIG. There was a problem that the test takes too much time.

Therefore, the present invention has been proposed to solve the above-mentioned problems of the prior art, and to inspect the hole of the PCB using image processing, but obtains the position and size information of the hole from the CAD data to inspect only the necessary 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,

A second step of acquiring an image of the inspection target printed circuit board by using an image acquisition device;

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 hand 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 by the hole inspection method according to the present invention and the image acquisition data of the actual hole.

5 and 6 are reference views 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, wherein the first step (ST101 to ST102) of analyzing CAD data to create reference hole data and an inspection target using an image acquisition device are shown. 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 first steps (ST101 to ST102). A fourth step ST106 of 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 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 inspecting a boundary portion of the circle in various directions from the center of the actual hole obtained in the third step ST105. It consists of a step 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 file, which is one of the standardized output formats that can be obtained after designing a PCB with CAD, and tool data representing the size (diameter) of the tool (e.g. drill). To create the reference hole data. (ST101 to ST102)

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

<Hall Gerber File>

G54D12 * X10815Y8207D10 * X10790Y5682D03 * X10790Y57777D03 * X10790Y5737D03 * X10777Y7927D03 * X10777Y7967D03 * X10770Y8176D03 * X10745Y8215D03 * X10732Y7957D03 * X10685Y3477D672 * 10

<Tool data>

No.PADDCODENo.VECTORDCODE

1R0121051R000.560

2R013.751152R001.7561

3R015.751253R00262

4R0201354R00363

5R023.6251455R00464

6R026.751556R005.2565

… … … … …

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 the X and Y coordinates (10790, 5682).

Through this analysis, reference hole data shown in FIG. 4A is generated, but only the holes to be examined among the plurality of holes on the PCB are converted into reference hole data.

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

Subsequently, 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 (a) of FIG. 5, the boundary between the hole and the background is found in the eight directions from the reference holes Vx and Vy, which are known in position, and eight boundary points <X (0), Y (0)>, <X (1), Y (1),... , &Lt; X (n), Y (n) >, and the centers Cx, Cy and radius r 'of the actual holes shown in FIG.

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

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

Next, the hole specification is examined by inspecting the boundary portions 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 decision 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 " After that, check whether this is larger than the normal land width (A).

Only the holes judged to be normal in both the steps 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 processed. (ST108)

On the other hand, the above-described series of steps ST105 to ST108 is repeatedly performed the same number of times as the number N of holes on the PCB to determine whether all 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 (3)

A first step of analyzing the CAD data to create reference hole data; A second step of acquiring an image of the inspection target printed circuit board by using an image acquisition device; 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. Hole inspection method of a printed circuit board. The method of claim 1, In the first step, the hole inspection method of the printed circuit board, characterized in that the existing hole data of only the hole to be inspected from the plurality of holes on the inspection target printed circuit board. The method of claim 1, And inspecting whether the periphery of the actual hole satisfies the normal land width in the fifth step or determining the minimum land width of the actual hole and comparing the result with the normal land width.