JP2005121417A - Inspection device for printed circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a wide-ranged and precise one-dimensional image of a printed circuit board, to cope with a mass production process, and to obtain an inspection result quickly and precisely, in an inspection device for inspecting optically through holes provided in the printed circuit board. <P>SOLUTION: The printed circuit board 1 is illuminated through a glass 2 with a diffusion processing function from a backface side (rear side) by a high-brightness line illumination lamp with a condenser. Transmission lights through through holes of the printed circuit board 1 are detected by two detecting parts 5a, 5b provided with a telecentric lens and a one-dimensional photoreception element, signals from the respective detecting parts 5a, 5b are calculated by parallel processing circuits 6a, 6b to be composed by an integration circuit 7, and the number of the through holes, positions thereof, dimensions thereof and the like are obtained based thereon. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a printed circuit board inspection apparatus that optically inspects the number, position, dimensions, and the like of through holes provided in a printed circuit board.

  In the mass production process of a printed circuit board, when inspecting the number, position, dimension, etc. of through holes provided in the printed circuit board, generally, the substrate surface is optically inspected. Conventionally, as an apparatus for performing such an inspection, an inspection apparatus using a one-dimensional or two-dimensional light receiving element and a general-purpose imaging optical system is known.

  FIG. 4 is a diagram showing a schematic configuration of a conventional inspection apparatus using a one-dimensional light receiving element. In the figure, 101 is a printed circuit board, 102 is a one-dimensional light receiving element, and 103 is an imaging optical system. The field of view of the detection unit composed of the one-dimensional light receiving element 102 and the imaging optical system 103 is indicated by a. By moving this detection unit in the main scanning direction b and the sub-scanning direction c, the entire surface of the printed circuit board 101 is detected. Inspection can be performed.

  FIG. 5 shows a specific configuration of the detection unit. Reference numeral 111 denotes a lens, and 112 denotes a one-dimensional light receiving element such as a CCD. The image of the through hole 113 provided in the printed circuit board 101 is imaged on the one-dimensional light receiving element 112 through the lens 111. Reference numeral 114 denotes an image of the imaged through hole 113.

Even if a two-dimensional light receiving element (CCD or the like) is used, the position and size of the through hole of the printed circuit board can be similarly examined. Further, it has been proposed to inspect the appearance of a printed circuit board using a laser beam (see, for example, Patent Document 1).
JP-A-8-5345

  By the way, in order to guarantee the position and size of the through hole of the printed circuit board, an inspection apparatus using a CCD or the like as described above is used. However, in the case of using a two-dimensional light receiving element, the inspection time is an object. In addition to increasing in proportion to the number of holes, there is a problem that the image cannot be captured while moving the detection unit, and thus cannot meet the tact required by the mass production process.

  On the other hand, inspection equipment using a one-dimensional light receiving element can capture images while moving at an arbitrary speed without depending on the number of holes to be inspected. It is adopted as an orientation device.

  However, when this one-dimensional light receiving element is used, the detection unit is scanned a plurality of times to obtain an image of the entire target printed circuit board. The wider the field of view of the detection unit, the shorter the inspection time. Due to the following reasons (a) to (d) due to the system, the field of view that can be captured at one time must be limited to a small range, and in order to inspect the entire area of the printed circuit board, the number of scans increases and the original high speed Sex was not utilized.

  (A) Since a lens that forms an image on a one-dimensional light receiving element generally has parallax, the periphery of the field of view is viewed from an oblique direction. When a thick target such as a printed circuit board is formed, Not only is the accurate shape not imaged, but only the information on the substrate surface is guaranteed, so even if there is an abnormality such as plating on the inner wall of the hole or foreign matter adhesion, there is a problem in the reliability of the inspection ( (See FIG. 5). This cannot be compensated by subsequent electrical and software processing.

  (B) Also, due to the above-described parallax, when a printed circuit board having a large thickness is observed with transmitted light even in the center of the visual field, the size of the hole is detected smaller than the actual size (see FIG. 5).

  (C) Furthermore, correction of aberrations (image formation errors) in the peripheral portion of the field of view that varies depending on the individual lens is extremely complicated, which imposes a heavy burden on software and increases processing time.

  (D) When a self-focusing lens array, which is a well-known technique, is used, screen uniformity can be easily obtained even with a large one-dimensional field of view, but the resolution is inferior to that of a general lens and the in-focus range (covered area) There is a problem that the depth of field) is narrow, and a parallax problem occurs in the same manner, so that the problem cannot be solved.

  The present invention has been made in view of the above-described problems, and can provide a wide-range and high-precision one-dimensional image, can be applied to a mass production process, and can obtain inspection results at high speed and high accuracy. An object of the present invention is to provide a substrate inspection apparatus.

  A printed circuit board inspection apparatus according to the present invention is an inspection apparatus that optically inspects a through hole provided in a printed circuit board, and includes illumination means for illuminating the printed circuit board, and light from the printed circuit board. Is provided with a one-dimensional light receiving element for receiving light through a telecentric lens, and a through hole of the printed circuit board is inspected from the output of the light receiving element.

  The telecentric lens includes a plurality of detection units having a one-dimensional light receiving element, and the depth of field of the telecentric lens is set to be large.

  According to the present invention, it is possible to obtain a wide-range and high-accuracy one-dimensional image, to cope with a mass production process, and to obtain an inspection result with high speed and high accuracy.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, showing the basic configuration of a printed circuit board inspection apparatus for optically inspecting the number, position, dimensions, etc. of through holes provided in a printed circuit board. Yes.

  In the figure, 1 is a printed circuit board, 2 is a glass with a diffusion processing function, 3 is a high-intensity line illumination lamp with a condensing device, and is provided as illumination means for illuminating the printed circuit board from the back side (rear side). ing. 4 is a detection unit having two detection units 5a and 5b each having a lens and a light receiving element, 6a and 6b are parallel processing circuits for processing signals from the detection units 5a and 5b, and 7 is a parallel processing circuit 6a. 6b is an integrated processing circuit for calculating the number, position, size, and the like of through holes provided in the printed circuit board 1 based on the output from 6b. Although not shown in the drawing, hardware and software for detecting and synthesizing the relative positions of the fields of view of the detectors 5a and 5b are provided.

  FIG. 2 is a cross-sectional view showing a configuration of each of the detection units 5a and 5b. A telecentric lens 11 is used as a lens, and a one-dimensional light receiving element 12 such as a CCD is used as a light receiving element on which an image of the through hole 13 of the printed circuit board 1 is formed. Reference numeral 14 denotes a hole image of the through hole 13 formed on the one-dimensional light receiving element 12 through the telecentric lens 11.

  In this embodiment, an XY orthogonal actuator is used as the moving means of the detection units 5a and 5b, and the entire surface of the printed circuit board 1 is scanned by each of the detection units 5a and 5b. The detection signals of the detection units 5a and 5b are calculated by the parallel processing circuit detection units 6a and 6b, respectively, and then synthesized by the integrated processing circuit 7 and provided on the printed circuit board 1 from the output of the integrated processing circuit 7. Data such as the number, position, and dimensions of the through holes 13 can be obtained.

  Here, since the telecentric lens 11 is a lens with zero parallax, an accurate image 14 of the through hole 13 is obtained as shown in FIG. Therefore, there is a problem that an accurate shape is not imaged in the periphery of the visual field as described above, and when a thick printed circuit board is observed with transmitted light, the size of the hole is detected smaller than the actual size, or an internal foreign object is missed. The problem is solved (see FIG. 2).

  In addition, the relative positional relationship of the field of view of the detection unit has been input as individual parameters with values measured by optical means during assembly, and the problem of parallax and depth of field has also been optically solved, The load of software correction processing is reduced, and the processing time is shortened.

  In addition, by designing the aperture value to be large, the in-focus range (depth of field) can be widened, and a sharp image 14 can be obtained even in the through hole 13 of the printed circuit board 1 having a large thickness.

  As described above, this embodiment realizes a printed circuit board inspection apparatus that can obtain a wide-range and high-precision one-dimensional image of the printed circuit board 1, can cope with a mass production process, and can obtain inspection results at high speed and high accuracy. can do.

  FIG. 3 is a diagram illustrating a detection operation of each of the detection units 5a and 5b described above. By mounting a plurality (two in this case) of detection units 5a and 5b composed of telecentric lenses 11a and 11b and one-dimensional light receiving elements 12a and 12b, the field of view can be arbitrarily expanded and high-speed inspection can be performed. Can do. When the visual fields of the detection units 5a and 5b are A and B, the entire visual field is A + B.

  Thus, by providing a plurality of detection units 5a and 5b, there are the following advantages compared to the case of a single detection unit. In other words, the capture cycle can be shortened by dividing the field of view and capturing simultaneously. In addition, aberration correction at the peripheral portion in the optical design of a single lens becomes easy, and as a result, the imaging performance of the entire field of view can be made uniform.

  In the above embodiment, in order to compensate for the reduction in the amount of received light by designing a large aperture value, high-luminance line illumination composed of line illumination with a condensing device and glass with a diffusion effect is adopted. However, the form of illumination is not limited to this.

  The present invention is effective for inspection of through holes provided in a printed circuit board.

The block diagram which shows the structure of the Example of this invention. Sectional drawing which shows the structure of the detection part of an Example Explanatory drawing which shows the detection operation of an Example Explanatory drawing showing the configuration of a conventional example Sectional drawing which shows the structure of the conventional detection part

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Printed circuit board 2 Diffusion processing glass 3 High-intensity line illumination lamp 5a Detection part 5b Detection part 6a Parallel processing circuit 6b Parallel processing circuit 7 Integrated processing circuit 11 Telecentric lens 11a Telecentric lens 11b Telecentric lens 12 One-dimensional light receiving element 12a Primary Original light receiving element 12b One-dimensional light receiving element 13 Through hole

Claims (3)

  An inspection apparatus for optically inspecting a through hole provided in a printed circuit board, comprising: an illuminating means for illuminating the printed circuit board; and a one-dimensional light receiving element for receiving light from the printed circuit board through a telecentric lens And a printed circuit board inspection apparatus for inspecting a through hole of the printed circuit board from an output of the light receiving element.   The printed circuit board inspection apparatus according to claim 1, further comprising a plurality of detection units including the telecentric lens and a one-dimensional light receiving element.   3. The printed circuit board inspection apparatus according to claim 1, wherein a depth of field of the telecentric lens is set large.

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