JP2000201000A - Circuit board and positioning thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of defective products and the chances of stoppage of a positioning equipment due to defective alignment marks formed on the surface of a circuit board. SOLUTION: On the surface of a circuit board 21, two pairs of alignment marks 22a, 22b and 23a, 23b are formed. When the circuit board 21 is positioned, the surface of the circuit board 21 is photographed by a camera and the image signal is image processed to search for the first pair of alignment marks 22a, 22b. If these alignment marks can be recognized normally, the circuit board 21 is positioned by means of an XY table, etc., with a coordinates at the center between the first pair of alignment marks 22a, 22b set as a reference. If either of the first pair of alignment marks 22a, 22b or both cannot be recognized normally because they have bleeding, chipping, etc., a second pair of alignment marks 23a, 23b are searched for. If they can be recognized normally, the circuit board 21 is positioned by means of the XY table, etc., with a coordinates at the center between the second pair of alignment marks 23a, 23b as the reference.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board positioning method and a circuit board for positioning a circuit board by optically recognizing a positioning mark formed on the surface of the circuit board.

[0002]

2. Description of the Related Art Conventionally, for positioning a ceramic circuit board, for example, as shown in FIG. 4, two positioning marks 12 are formed on both ends on a substantially diagonal line of a ceramic circuit board 11 by thick film printing or the like. The surface of the ceramic circuit board 11 is photographed by a camera, and the image signal
Of the positioning marks 12
The ceramic circuit board 11 is positioned with reference to the center position of No. 2.

[0003]

Generally, the positioning marks 12 formed on the surface of the ceramic circuit board 11 are often formed into a circular or square shape by thick-film printing, for example, as shown in FIG. ), The circular positioning mark 12 is not always formed in an accurate circular shape.
As shown in FIG. 5B, the outer periphery of the positioning mark 12 spreads irregularly due to the bleeding of the paste during printing.
Alternatively, as shown in FIG. 5C, a part of the positioning mark 12 may have a missing shape. Since the positioning mark 12 having such a defect cannot be recognized as a positioning mark and the positioning of the ceramic circuit board 11 cannot be performed, it is determined to be defective and the yield is reduced, or the positioning device is stopped. As a result, productivity may be reduced.

As a countermeasure, if the identification condition of the positioning mark is relaxed so that the positioning mark 12 having some defect can be recognized, the center position of the positioning mark 12 is detected depending on the presence or absence of the defect. Since the positioning accuracy is reduced, the positioning accuracy required for the small-sized ceramic circuit board 11 which is mounted at a high density cannot be secured. Further, if the conditions for identifying the positioning mark are relaxed, the positioning mark 12 can be easily erroneously recognized due to dust or dirt attached to the surface of the ceramic circuit board 11, and erroneous positioning may be performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to significantly reduce the occurrence of defective products and stoppage of a positioning device due to a defect of a positioning mark, thereby improving the yield and the productivity. It is an object of the present invention to provide a circuit board positioning method and a circuit board which can satisfy the requirements of the above, and also can meet the requirements of the improvement of the positioning accuracy accompanying high-density mounting and miniaturization.

[0006]

According to a first aspect of the present invention, there is provided a method of positioning a circuit board, comprising forming a plurality of sets of positioning marks on a surface of the circuit board and recognizing the marks by image recognition means. If one set of positioning marks cannot be recognized normally, another set of positioning marks is searched. If the other set of positioning marks can be recognized normally, the position of the other set of positioning marks is searched. Is used to position the circuit board.
For example, when two sets of positioning marks are formed, when positioning is first performed using the first set of positioning marks, if the positioning marks cannot be recognized normally, the second set of positioning marks is searched for and searched. If it can be recognized normally, 2
The circuit board is positioned based on the position of the positioning mark of the set. In this way, even if the first set of positioning marks has a defect such as bleeding or chipping, the circuit board can be accurately positioned using the second set of positioning marks.

In this case, it is preferable to form two sets of positioning marks symmetrically with respect to the center line of the circuit board. In this case, if the center line of the circuit board is taken as the coordinate axis, the relationship between the coordinates of the first set of positioning marks and the coordinates of the second set of positioning marks is only inverted ±.
Coordinate setting processing becomes easy.

According to a third aspect of the present invention, when a circuit board on which a plurality of sets of positioning marks are formed so that the positioning marks recognized by the image recognizing means can be selected is used, the positioning method according to the first aspect is used. The occurrence of defective products due to defects and the stoppage of the positioning device can be greatly reduced.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment (1) of the present invention will be described below with reference to FIGS. The circuit board 21 is, for example, a single-layer board or a multilayer board made of ceramic such as glass ceramic or alumina. On the surface of the circuit board 21, for example, two sets of positioning marks 22a, 22b, 23
a and 23b are formed. These positioning marks 22a, 22b, 23a, 23b are formed simultaneously with the surface conductor pattern (not shown) by printing and baking of a conductor paste or by photolithography. Alternatively, a part of the surface conductor pattern may be used as a positioning mark. To form

Each set of positioning marks 22a, 22b, 2
3a and 23b are located at both ends on a substantially diagonal line of the circuit board 21, and one set of the positioning marks 22a and 2b.
2b and the other pair of positioning marks 23a and 23b are formed at symmetrical positions with respect to the center line (Y-axis or X-axis of the coordinates) of the circuit board 21. Each positioning mark 22a,
22b, 23a, 23b are circular, square, cross, etc.
Any shape may be used, but they are all the same size and the same shape. For example, in the case of a circular shape, the diameter is about 0.5 mm to 1 mm.

The positioning of the circuit board 21 is performed by a control computer (not shown) of the positioning device in accordance with the positioning control program shown in FIG. First, in step S1, the surface of the circuit board 21 conveyed to the positioning station is photographed by a camera (image recognition means), and in the next step S2, image signals output from the camera are subjected to image processing to form a set. The eye positioning marks 22a and 22b are searched. Thereafter, step S3
Then, it is determined whether or not the first set of positioning marks 22a and 22b can be recognized normally. If the first set of positioning marks 22a and 22b can be recognized normally, the process proceeds to step S4.
The circuit board 21 is positioned using an XY table or the like with reference to the center coordinates of.

If the first set of positioning marks 22a, 2
If one or both of them has a defect such as bleeding or chipping and cannot be recognized normally, the process proceeds to step S5, where the image signal output from the camera is subjected to image processing to perform the second set of positioning marks 23a and 23b. Search for. Thereafter, in step S6, it is determined whether or not the second set of positioning marks 23a and 23b has been normally recognized. If the second set of positioning marks 23a and 23b can be recognized normally, the process proceeds to step S7.
The circuit board 21 is moved in XY with reference to the center coordinates of a and 23b.
Position using a table or the like.

The second set of positioning marks 23a, 23
If b cannot be recognized normally, the process proceeds to step S8, and error processing such as ejection of the circuit board 21 and notification of occurrence of a defective product is performed.

According to the embodiment (1) described above,
On the surface of the circuit board 21, two sets of positioning marks 22a, 2
Since the 2b, 23a and 23b are formed, the circuit board 21 is positioned using the second set of positioning marks 23a and 23b even if the first set of positioning marks 22a and 22b has a defect such as bleeding or chipping. be able to.

According to the experimental results of the present inventor, a diameter of 1 mm
Circular positioning marks 22a, 22b, 23a, 23
When the recognition processing was performed on the first set of positioning marks 22a and 22b using the sample substrate on which “b” was formed, three of the 550 sample substrates failed to recognize (recognition failure rate = 3/550). = 0.5%). For these three sample substrates, the second set of positioning marks 23
As a result of performing the recognition processing of a and 23b, the second set of positioning marks 23a and 23b was normally recognized on all the sample substrates (recognition failure rate = 0%).

If the probability of recognition failure in the first recognition processing is 3/550, the probability of recognition failure in the second recognition processing is theoretically (3/550) × (3/550). 55
0) = 0.003%.

As described above, in the present embodiment (1), two sets of positioning marks 22a and 22 are formed on the surface of the circuit board 21.
When the first set of positioning marks 22a and 22b cannot be recognized normally, the second set of positioning marks 23a and 23b is searched. The circuit board 21 can be positioned using the second set of positioning marks 23a and 23b even if there is a defect such as bleeding or chipping in the portions 22a and 22b. Thereby, the positioning marks 22a, 2
The occurrence of defective products due to the defect 2b and the stoppage of the positioning device can be significantly reduced, the yield can be improved, the productivity can be improved, and the production cost can be reduced. In addition, since the identification rate can be increased without relaxing the identification conditions of the positioning marks 22a, 22b, 23a, and 23b, the positioning accuracy required for the high-density small circuit board 21 is sufficiently ensured. Therefore, it is possible to satisfy the demand for improvement of positioning accuracy accompanying high-density mounting and miniaturization.

Moreover, in this embodiment (1), the first set of positioning marks 22a and 22b and the second set of positioning marks 23a and 23b are aligned with the center line of the circuit board 21 (Y coordinate).
(X axis or X axis), the coordinates of the first set of positioning marks 22a and 22b and 2
The relationship with the coordinates of the positioning marks 23a and 23b of the set is only inverted ±, and there is also an advantage that the coordinate setting processing becomes easy.

However, the present invention is not limited to forming two sets of positioning marks at positions symmetrical with respect to the center line of the circuit board 21, but as in the embodiment (2) of the present invention shown in FIG. First set of positioning marks 22a, 22
b and the second set of positioning marks 23a and 23b may be formed at positions that are asymmetric with respect to the center line (Y-axis or X-axis of the coordinates) of the circuit board 21. In this case, the coordinates of the first pair of positioning marks 22a and 22b are set in the X-axis direction
A second set of positioning marks 2 at the position translated in the axial direction
If 3a and 23b are formed, only the X coordinate or the Y coordinate of the latter need only be changed with respect to the former, and the coordinate setting process is easy.

However, according to the present invention, both the X and Y coordinates of the second set of positioning marks 23a and 23b may be changed with respect to the coordinates of the first set of positioning marks 22a and 22b. Even in this case, the intended object of the present invention can be sufficiently achieved.

In the above embodiments (1) and (2), the circuit
Although two sets of positioning marks were formed on the surface of the substrate 21,
Three or more sets of positioning marks may be formed. In general,
If N sets of positioning marks are formed, the maximum number of positions is N
The recognition process of the decision mark can be repeated. This place
If the recognition failure rate per recognition process is a%, then N
Probability that the recognition process will be repeated in the end
Is (a / 100)^N And extremely small.

In each of the above embodiments (1) and (2), two sets of positioning marks are used. However, three or more sets of positioning marks may be used. Further, the position of the positioning mark is not limited to the diagonal line of the circuit board, and may be a position apart from the diagonal line. In addition, in the present invention, the circuit board 21 is not limited to the ceramic circuit board, but may be a resin board or a metal board.

[0023]

As is apparent from the above description, in the first and third aspects of the present invention, a plurality of sets of positioning marks are formed on the surface of a circuit board, and the positioning marks used for positioning are selected. Since multiple types of positioning can be performed, the occurrence of defective products due to defects in the positioning marks and the stoppage of the positioning device can be greatly reduced, and the demands for higher yield and higher productivity can be satisfied. It can also meet the demand for improved positioning accuracy due to mounting and miniaturization.

Furthermore, in the second aspect, since two sets of positioning marks are formed at positions symmetrical with respect to the center line of the circuit board, the processing for setting the coordinates of the two sets of positioning marks can be performed efficiently.

[Brief description of the drawings]

FIG. 1 is a plan view of a circuit board illustrating a method for positioning a circuit board according to an embodiment (1) of the present invention.

FIG. 2 is a flowchart showing a processing flow of a positioning control program.

FIG. 3 is a plan view of a circuit board illustrating a method for positioning the circuit board according to the embodiment (2) of the present invention;

FIG. 4 is a plan view of a circuit board for explaining a conventional method of positioning the circuit board.

5A is a plan view showing a normal shape of a positioning mark, FIG. 5B is a plan view showing a shape of a positioning mark having bleeding, and FIG. 5C is a plan view showing a shape of a positioning mark having chipping. Plan view

[Explanation of symbols]

21: circuit board, 22a, 22b, 23a, 23b: positioning mark.

Claims (3)

[Claims] 1. A circuit board positioning method for recognizing a positioning mark formed on a surface of a circuit board by image recognition means and positioning the circuit board with reference to the position of the positioning mark. When a plurality of sets of positioning marks are formed, and one set of positioning marks to be recognized by the image recognition means cannot be normally recognized, another set of positioning marks is searched for and the other set of positioning marks is searched. A method of positioning a circuit board, characterized in that if the mark can be recognized normally, the circuit board is positioned based on the position of the other set of positioning marks. 2. The method according to claim 1, wherein two sets of positioning marks are formed at positions symmetrical with respect to a center line of the circuit board. 3. A circuit board having a positioning mark to be recognized by an image recognition means on a surface of a substrate, wherein a plurality of sets of positioning marks are formed on the surface of the substrate so that the positioning mark to be recognized by the image recognition means can be selected. A circuit board characterized by the above-mentioned.