JP3203853B2 - Inspection device for mounted printed circuit boards - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for inspecting a mounted printed circuit board, and irradiates the mounted printed circuit board with a finely narrowed light beam, and detects the reflected light to thereby shift the position of a mounted component. Inspection for missing parts, defective solder, etc.

[0002]

2. Description of the Related Art In recent years, non-contact methods using the principle of triangulation have been used for inspection of misalignment, missing parts, defective soldering, and the like of components on a mounted printed circuit board.
The board is scanned while vertically irradiating the narrowed beam light onto the mounted printed board, and the reflected light diffused from the irradiation position of the minute beam light is received by the photoelectric conversion element to inspect the surface shape of the board. That is being done.

[0003]

In the conventional apparatus for inspecting a mounted printed circuit board, the reflected light diffused from the irradiation position of the minute beam light is reflected in the optical axis direction (substantially vertical direction) of the minute beam light. By guiding the reflected light to the photoelectric conversion element, it is used as luminance data for detecting the attachment of solder. The present invention provides an inspection apparatus utilizing such reflected light in the vertical direction, which further improves the detection accuracy, and provides an apparatus for acquiring and inspecting the three-dimensional shape of a mounted printed circuit board to be inspected. Aim.

[0004]

In order to achieve this object, a mounted printed circuit board inspection apparatus according to the present invention is provided with an apparatus for inspecting a mounted printed circuit board out of reflected light diffused from an irradiation position of a beam light vertically irradiated on the mounted printed circuit board. A photoelectric conversion means for receiving reflected light in the vertical direction along the irradiation optical axis of the beam light, and converting the reflected light into an electrical output corresponding to the amount of received light ;
A cylinder having a flat light-passing surface for scanning the light beam
Focusing reflected light reflected in the vertical direction using a lithographic lens
It is characterized by doing so.

[0005]

According to the above construction, of the reflected light diffused from the light beam irradiation position, the reflected light reflected in the vertical direction along the irradiation light axis of the light beam is a photoelectric conversion element for electrically outputting the reflected light.
When receiving light, focus the reflected light that is reflected in the vertical direction.
Thus, the solder inspection can be performed with higher accuracy.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an apparatus for inspecting a mounted printed circuit board to which the present invention is applied. In FIG. 1, reference numeral 1 denotes a light source for generating a minute light beam to irradiate the mounted printed circuit board 6. Reference numeral 2 denotes a collimating lens system for condensing the minute beam light from the light source 1 to make it a parallel light beam. 3 deflects the parallel light beam, and
This is a polygon mirror for deflecting light reflected from the mounted printed circuit board 6. Reference numeral 4 denotes a polygon motor that drives the polygon mirror 3 to rotate. Reference numeral 5 denotes a light projecting fθ lens that condenses the parallel light beam deflected by the polygon mirror 3 and irradiates the mounted printed circuit board 6 substantially perpendicularly. Reference numeral 6 denotes a mounted printed board to be inspected.

7, 8, 9, and 10 receive reflected light from the small beam light irradiation position on the mounted printed circuit board 6 from four directions, and receive the reflected light, respectively, using a light receiving fθ lens 11,
An optical path correction optical system that corrects the optical path of the reflected light to guide the light to 12, 13, and 14. Receiving fθ lenses 11, 12,
Reference numerals 13 and 14 are for guiding the reflected light that has passed through the optical path correction optical systems 7, 8, 9 and 10 to the polygon mirror 3. 15, 16, 17, and 18 are light receiving fθ lenses 11,
This is a PSD (semiconductor position detecting element) lens for condensing the reflected light passing through 12, 13, and 14 and deflected by the polygon mirror 3. 19, 20, 21, and 22 are PS
It is a PSD that receives the reflected light condensed by the D lenses 15, 16, 17, and 18, and generates an electrical output corresponding to the light receiving position.

Reference numeral 23 denotes a mounted printed board which returns along the light projecting optical axis through the light projecting fθ lens 5 and the polygon mirror 3 among the reflected light from the minute beam light irradiation position on the mounted printed circuit board 6. The tunnel mirror deflects reflected light in a direction perpendicular to the substrate 6. Reference numeral 24 denotes a lens for collecting the reflected light deflected by the tunnel mirror 23. Reference numeral 25 denotes an aperture that blocks reflected light from directions other than the vertical direction. Reference numeral 26 denotes a photodiode that receives the reflected light in the vertical direction and converts the amount of received light into an electrical output.

Reference numeral 27 denotes a table for fixing the mounted printed circuit board 6. Reference numeral 28 denotes a ball screw that moves the table 27 in the sub-scanning direction (the direction of the arrow y) by rotating. Reference numeral 29 denotes a ball screw motor for rotating the ball screw 28. Reference numeral 30 denotes a guide rail for guiding the table 27. The operation of the mounted printed circuit board inspection apparatus configured as described above will be described.

The minute light beam generated from the light source 1 is converted into a parallel light beam by the collimating lens system 2, passes through the hole of the tunnel mirror 23, is deflected by the polygon mirror 3, is condensed by the light projecting fθ lens 5, and The light beam is irradiated substantially perpendicularly onto the mounted printed circuit board 6 as a light beam irradiation optical axis. At this time, the minute light beam generated by the light source 1 scans the mounted printed circuit board 6 in the main scanning direction (the direction of the arrow x) in the drawing with the rotation of the polygon mirror 3 driven by the polygon motor 4. . And
The reflected light diffused from the scanning position on the mounted printed circuit board 6 is guided to the light receiving fθ lenses 11, 12, 13, and 14 by the optical path correction optical systems 7, 8, 9, and 10.

The optical path correction optical systems 7, 8, 9, and 10 are provided for irrespective of a change in the scanning position of the minute beam light among the reflected light diffused from the irradiation position on the mounted printed circuit board 6.
The scanning direction when the angle (hereinafter referred to as the tilt angle) between the optical axis of the microbeam light irradiation and the optical axis of the reflected light is substantially constant, and the reflected optical axis is projected on a plane perpendicular to the optical axis of the microbeam light irradiation Angle (hereinafter, the allocation angle) is substantially constant,
That is, reflected light having a substantially constant direction vector is received. Irrespective of the change in the scanning position, the light is made to enter the light receiving fθ lenses 11, 12, 13, and 14 substantially perpendicularly to the position in the main scanning direction (arrow x direction) at the same position as the optical axis of the microbeam light irradiation, Furthermore, even if the scanning position changes, the reception of reflected light f
The reflected light is guided so that the incident position of the θ lens in the sub-scanning direction (the direction of the arrow y) does not change.

Since the light receiving fθ lens 13 has the same shape as the light projecting fθ lens 5, the reflected light is guided to the polygon mirror 3 by following the same path as the light beam of the projected light. Then, the reflected light is deflected by the polygon mirror 3 and an image of the reflected light is formed at a position on the PSD 21 according to the height of the irradiation position of the minute light beam on the printed circuit board 6 irrespective of a change in the scanning position of the minute light beam. Imaged. Other optical path correcting optical system 7,
8, 10 are the same, and the optical path correction optical system 7,
The reflected light received by 8, 10 is the received light fθ lens 11, 1
2 and 14 and the PSD lenses 15, 16 and 18, and are guided to the PSDs 19, 20 and 22.

The reflected light from the printed circuit board 6 thus mounted has a PSD corresponding to the height of the minute beam light irradiation position.
Since the image is formed at the upper position, the PSD 19, 2
The height of the minute beam light irradiation position is determined using the electrical outputs from 0, 21, and 22. The data measured by the PSDs 19, 20, 21, and 22 arranged in these four directions is subjected to processing such as selection described later, and the correct height is measured regardless of the surface condition of the measurement object. Can be.

The reflected light reflected from the minute beam light irradiation position in the direction of the minute beam light irradiation optical axis (substantially perpendicular direction) passes through the light projecting fθ lens 5, polygon mirror 3, tunnel mirror 23, lens 24 and aperture 25. Through the photodiode 26. At this time, the reflected light in the vertical direction is
5 and lens 24, and the collected reflected light is received by photodiode 26. Further, light other than the reflected light in the optical axis direction of the microbeam light irradiation is blocked by a diaphragm 25 provided between the lens 24 and the photodiode 26. Therefore, only the amount of reflected light reflected from the minute beam light irradiation position in the direction of the minute beam light irradiation optical axis can be correctly measured.

Thus, the four PSDs 19, 20, 2
At 1 and 22, four luminance data and height data can be acquired from four directions for one measurement point. As a method of selecting four luminance data, there is a method of obtaining the maximum value of the four data. As a method of selecting height data, for example, a method of removing data for which measurement accuracy cannot be guaranteed and taking an average of the remaining data, or when the number of remaining data is large, the maximum level data and the minimum level data are used. There is a method of removing and averaging the remaining data.

Since the photodiode 26 receives the reflected light in the vertical direction from the mounted printed circuit board 6, the reflected light in the vertical direction is generated when the inclination of the solder surface is gentle or when there is no solder. The output increases as the number increases, and conversely, when the inclination of the solder surface is steep, the reflected light in the vertical direction decreases and the output decreases. For this reason,
When the output of the PSD is small and the height of the solder surface cannot be measured correctly, the luminance information of the photodiode 26 can be referred to.

Then, the height and luminance information subjected to the selection processing is compared with the stored height and luminance information obtained from the reference mounted printed circuit board as a reference in advance to determine the mounting state of the mounted printed circuit board. The quality can be checked.

In the inspection apparatus for a mounted printed circuit board shown in FIG. 1, the amount of reflected light in the vertical scanning direction in the sub-scanning direction with respect to the mounted printed circuit board is equal to the light projection f.
is determined by the width of the θ lens 5 in the sub-scanning direction,
If the length of the lens in the sub-scanning direction is not sufficient, the amount of light received by the photodiode decreases, and the inspection accuracy decreases.

Therefore, as shown in FIG. 2 , a special cylindrical lens 40 is arranged in order to increase the amount of received reflected light in the vertical direction. In the drawing, the reflected light in the vertical direction with respect to the mounted printed circuit board is shown by a solid line, and the minute light beam of the projected light is shown by a dotted line. The special cylindrical lens 40 is a lens having a curvature only in the sub-scanning direction, and has a shape in which a part of the vertex of the R surface is cut to be flat. By arranging the special cylindrical lens, the light reflected in the vertical scanning direction in the vertical direction with respect to the mounted printed circuit board can be collected, and the inspection accuracy by the photodiode 26 can be improved.

At this time, the small beam light after passing through the light projecting fθ lens 5 is irradiated on the mounted printed circuit board 6 through the special cylindrical lens 40, but passes through the plane portion of the special cylindrical lens 40, so that the special cylindrical lens Printed circuit board 6 mounted without being affected by 40
Is irradiated. The reflected light in the direction perpendicular to the mounted printed circuit board 6 passes through the R surface of the special cylindrical lens 40, so that light in the sub-scanning direction is collected,
The quantity of light that guarantees the inspection accuracy of the photodiode can be secured.

[0021]

As described above, according to the present invention, out of the reflected light of the minute beam light vertically irradiated on the mounted printed board, the reflected light in the substantially vertical direction along the optical axis of the minute beam is received. Te, in the testing apparatus of the loaded printed board inspecting the surface shape, shadow scanning of the substrate of the micro-bi chromatography beam light
Using a cylindrical lens processed so as not to affect the sound
Thus , the inspection accuracy can be increased by increasing the amount of received light .

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a device for inspecting a mounted printed circuit board to which the present invention is applied;

FIG. 2 is an explanatory view of a main part of a device for inspecting a mounted printed circuit board according to an embodiment of the present invention;

[Explanation of symbols]

 Reference Signs List 1 light source 2 collimating lens system 3 polygon mirror 4 polygon motor 5 light emitting fθ lens 6 mounted printed circuit board 7, 8, 9, 10 optical path correction optical system 11, 12, 13, 14 light receiving fθ lens 15, 16, 17, 18 PSD lens 19, 20, 21, 22 PSD 23 Tunnel mirror 24 Lens 25 Aperture 26 Photodiode 40 Special cylindrical lens

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yuji Ono 2-2-110 Kotobukicho, Takamatsu-shi, Kagawa Prefecture Inside Matsushita Kotobuki Electronic Industry Co., Ltd. (72) Inventor Hidenori Nagata 2-2-2 Kotobukicho, Takamatsu-shi, Kagawa Prefecture No. 10 Matsushita Hisashi Denshi Kogyo Co., Ltd. (56) Reference JP-A-2-18719 (JP, A) Japanese Utility Model Application 58-123308 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB G01B 11/00-11/30 102 G01N 21/84-21/958 G02B 26/10 H05K 3/34 H05K 13/08

Claims (1)

(57) [Claims] 1. A reflected light in a vertical direction along an irradiation optical axis of the beam light, of reflected light diffused from an irradiation position of a beam light that scans while vertically irradiating a mounted printed circuit board. And a photoelectric conversion means for converting the reflected light reflected in the vertical direction using a cylindrical lens having a flat surface through which the light beam passes for scanning the substrate. An inspection device for a mounted printed circuit board, which is configured to collect light.