JPH02141604A - Method for inspecting substrate - Google Patents

Abstract

PURPOSE:To automatically inspect a substrate regardless of the angle of the surface of a soldered region by applying a fluorescent agent to the periphery of the soldered region and exposing the coating surface to light to excite the fluorescent agent and irradiating the soldered region with the light caused by the excited fluorescence. CONSTITUTION:A fluorescent agent is applied to at least the periphery of the soldered region 18 of a mounting part 21 on the surface of a substrate 20 and, when this fluorescent agent coated surface 50 is exposed to the light L1 from a ring-shaped light emitting body 17, light L2 is emitted. In this case, with respect to a part where the angle of the surface of the region 18 to the substrate 20 is gentle, the light L1 is reflected from said gentle slope surface and the reflected light image of said surface is directly taken by a camera 19. With respect to a part where the angle of the surface of the region 18 is steep, the secondary illumination light due to the fluorescence L2 is reflected from said steep slope surface and the reflected light image is taken by the camera 19. Therefore, even with respect to the soldered region having a steep angle and the soldered region containing a part having a steep angle, and properties of the soldered part can be judged and the soldered region can be automatically inspected.

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a board inspection method used to inspect the quality of soldering of components mounted on a board.

<Prior art> For example, visual inspection has been used to inspect the mounting condition of surface-mounted components on a board. This visual inspection determines solubility, short circuits, poor continuity, etc. However, in such visual inspection, the occurrence of inspection errors is unavoidable, the judgment results vary depending on the person conducting the inspection, and there is a limit to the inspection processing capacity.

Therefore, in recent years, various automatic inspection devices that can automatically perform this type of inspection have been proposed.

FIG. 8 shows an example of an automatic inspection device that can detect three-dimensional shape information. The device shown in the figure irradiates a slit beam 1 from a laser light source to a soldering site on a substrate 2, and generates an optical cutting line 3 that is distorted along the surface shape of the surface of the substrate 2, including the soldering site. It is something to do. The reflected light image of this optical cutting line 3 is captured by an imaging device 4, and by checking the distortion state of the captured pattern, the three-dimensional shape of the soldering site is detected.

However, in the case of this inspection method, only the shape information of the portion irradiated with the slit light 1 is obtained, and it is difficult to grasp the three-dimensional shape of the other portions.

As a method to solve this problem, by irradiating the surface of the soldering area with light having different incident angles and capturing the pattern of each reflected light image of the soldering area, the orientation of the curved surface elements of the soldering area can be adjusted. There is a method to detect gender.

This method focuses on the fact that when a fixed pattern of light beams is applied to an inspection object, the pattern of the reflected light beam is deformed according to the three-dimensional shape of the inspection object, and the shape of the inspection object can be determined from the deformation pattern. It is estimated.

FIG. 9 is a diagram explaining the principle of this method, and shows the positional relationship between the detection system consisting of the light projection device 5 and the imaging bag R6, and the soldering site 7 to be inspected.

In the figure, when a light beam 8 is projected from the light projecting device 5 onto the surface of the soldering site 7 at an incident angle i, a reflected light beam 9 at an angle of V (=i) enters the imaging device 6 located directly above and is detected. be done. This means that it has been detected that the curved surface element of the soldering site 7 illuminated by the light beam 8 is oriented at an angle of i with respect to the reference plane 10. Therefore, if a plurality of light projecting devices with different incident angles project light onto the soldering site 7, which is made up of a large number of curved elements oriented in different directions, a group of curved elements corresponding to each incident angle is projected onto the imaging device. 6, and thereby it is possible to detect the orientation of each curved surface element of the soldering site 7, that is, the surface texture of the soldering site.

Furthermore, if the light projecting device 5 projects a light beam 8 having a width of 2Δi with an incident angle from i+Δi to i−Δi, a reflected light beam 9 having a width corresponding to the width is detected by the imaging device 6. That will happen.

In other words, in this case, the inclination angle with respect to the reference plane lO is i+Δ
It is possible to detect curved surface elements having angles of width from i to i-Δi.

Furthermore, as shown in FIG.
If it is ring-shaped and installed horizontally, no matter what rotation angle the surface of the soldering part 7 has with respect to the axis perpendicular to the reference plane 10, 7 is constant, and the orientation of the curved surface element in the rotation angle direction is eliminated, so only the inclination angle with respect to the reference surface 10 is detected.

Furthermore, as shown in FIG.
, 12.13, curved surface elements having orientations corresponding to the incident angles of the light beams 14, 15, 16 from each light emitting body can be detected in greater detail as described above.

Now, if three ring-shaped light emitters 11, 12.13 with radius r (where n = t 1213 ) are installed horizontally at a height h n (n = 11213 ) with respect to the reference plane 10, then , each light beam 14,1 to the soldering site 7
The angle of incidence of 5.16 is III (n=1.2.3
), and each curved surface element having an inclination angle of 17 at the soldering site 7 can be detected by the imaging device 6. At this time, since the size of the curved surface element is sufficiently small compared to the total optical path length from each light emitting body 11, 12, 13 to the imaging device 6 via the surface of the soldering site 70, the angle of incidence, that is, can be detected using the following equation. What is necessary is to determine the inclination angle of the curved surface element.

As a method for inspecting the appearance of soldered parts based on the above principle, a method has been proposed in which a white light source is used for each of the light emitters 11, 12 and 13 (Japanese Patent Laid-Open No. 61-2936
No. 57). In this inspection method, in order to mutually identify the reflected light images by the three light emitters 11 and 12.13 having different incident angles with respect to the soldering site, the light emitters 11 and 12.13 are placed at different times. The lights are turned on and off at the appropriate timing.

However, this method requires a memory to store each image obtained at different light emitting timings, a calculation device to process these images as the same visual field image, and a computer to instantaneously turn on each light emitting body. A lighting device and the like are required, which is technically complicated, and this also poses problems in terms of cost and reliability.

Therefore, in order to solve the problems of this time sharing system all at once, the inventor of the present invention recently proposed a board inspection apparatus having the configuration shown in FIG. This board inspection equipment is
The details will be described later, but there is a light projector 24 for irradiating red light, green light, and blue light with different angles of incidence onto the surface of the soldering site, and a light projection unit 24 for irradiating the surface of the soldering site with reflected light images for each hue. It is composed of an imaging section 25 for taking an image, and a processing section 26 for detecting the properties of each curved surface element of the soldering site from the imaging pattern obtained by the imaging section 25. Three ring-shaped light emitters 2B and 29.30 are used, each emitting light, green light, and blue light. Each of the light emitters 2B and 29.30 has a luminescence energy distribution with respect to wavelength such that white light is produced by combining the light from each light emitter. The amount of light can be adjusted.

According to this board inspection device, when red light, green light, and blue light are irradiated from the respective light emitters 28.29° 30 at different incident angles to the soldering area, red, green, and blue light from the surface of the soldering area is detected. The respective reflected light images are simultaneously separated and detected by the imaging section 25. In this case, each light emitter 2
Red light, green light, and blue light according to , color codes, etc.) and board pattern information (various marks, etc.), which is essential for automatic inspection of board-mounted components, can be detected.

<Problems to be Solved by the Invention> However, in the case of such a board inspection device, when the surface of the soldering area is a gentle slope, the reflected light is guided to the imaging section 25, but the reflected light is not reflected from the soldering area. When the surface is a steep slope (angle of 45° or more with respect to the substrate surface), the reflected light does not enter the imaging section 25, making it difficult to inspect the properties of the soldered area.

This invention was made by focusing on the above problem, and by inspecting the surface of a steep soldering part using secondary illumination light, the property can be inspected regardless of the angle of the surface of the soldering part. The purpose of the present invention is to provide a board inspection method that enables the following.

<Means for Solving the Problems> In order to achieve the above object, the present invention irradiates the mounted components on the board with light using a ring-shaped light emitter, and collects the reflected light image from the soldering site by I. In a board inspection method in which the properties of a soldering site are detected from the imaged pattern, a fluorescent agent is applied at least around the soldering site of a mounted component on the surface of the board, and the ring is applied to the surface coated with the fluorescent agent. The light from the shaped light emitting body is applied to excite the light, and the secondary illumination light from the excitation light is applied to the soldering site, and an image of the reflected light is captured.

If the angle of the surface of the soldering part is gentle, the light from the ring-shaped light emitter will be reflected on the gentle slope and an image of the reflected light will be captured. If the slope is steep, secondary illumination light from the excitation light will be reflected on the steep slope, and a reflected light image will be captured. Therefore, automatic inspection is possible even for soldering parts with steep angles.

<Example> FIG. 1 shows the principle of the substrate inspection method of the present invention.

In this board inspection method, a ring-shaped light emitter J7 irradiates light onto the mounted component 21 on the board 2o, an image of reflected light from the surface of the soldering area 18 is captured by the imaging unit 19, and the imaged part When detecting the properties of the soldering site 18 from the ring, a fluorescent agent is coated around the soldering site 18 of the mounted component 21, and the fluorescent agent coated surface 50 is coated with a fluorescent agent from the ring-shaped light emitting body 17. When the light hits, light L8
is now excited.

In this case, for the part of the surface of the soldering part 18 that is at a gentle angle with respect to the substrate 20, the light from the light emitter 17 is reflected on the gentle slope and a reflected light image is directly captured. Regarding the part of the surface 18 where the angle is steep, the secondary illumination light by the excitation light L2 is reflected by the slope, and a reflected light image is captured. Therefore, it is possible to judge the properties of soldering parts even for soldering parts with steep angles, and also for soldering parts including parts with steep angles, and automatic inspection of soldering parts is possible.

FIG. 2 shows a schematic configuration of a board inspection apparatus to which the board inspection method of the present invention is applied.

This board inspection apparatus uses feature parameters (judgment data) of the inspection area of each component 21S on the reference board 2O3 obtained by imaging the reference board 2O3, and a board to be inspected 20T.
Characteristic parameters of the inspection area of each component 21T on the substrate to be inspected 20T obtained by imaging (data to be inspected)
This is to check whether each of these parts 21T is correctly mounted and soldered by comparing the X-axis table section 22 and the Y-axis table section 23.
．． Light projecting section 24. Imaging unit 25. The configuration includes a processing section 26 and the like.

As shown in FIG. 3, the reference substrate 2O3 and the substrate to be inspected 20T are obtained by first performing etching, resist processing, hole-drilling, etc. on a raw substrate covered with copper foil on both sides (or one side). A raw substrate 45 shown in Figure (A) is formed.

Next, mark each component mounting position on this base board 45 as shown in FIG.
After forming a fluorescent agent coated surface 50 by applying paint or ink 46 containing a fluorescent agent by silk screen printing, resist painting, dot marking, etc., as shown in FIG. As shown in C), a predetermined part 213
and 21T are mounted to form a reference substrate 20S and a substrate to be inspected 20T.

The above-mentioned fluorescent agent can be selected as appropriate; if it is a red fluorescent agent, green or blue fluorescent light will be excited by green light or blue light, and if it is a green fluorescent agent, blue fluorescent light will be excited by blue light. Light is excited.

In this embodiment, the fluorescent agent coated surface 50 is formed partially to surround each land portion 47, 48 on which a component is mounted, as shown in FIG. 4, but is not limited thereto. As shown in FIG. 5, each land portion 47, 48 may be left and formed over the entire surface of the substrate.

Returning to FIG. 2, the X-axis table section 22 and the Y-axis table section 23 are each equipped with a motor (not shown) that operates based on a control signal from the processing section 26. The axis table section 22 moves the imaging section 25 in the X direction, and the Y axis table section 23 moves the imaging section 25 in the X direction.
S.

The conveyor 27 supporting 20T is moved in the Y direction.

These substrates 2O3 and 20T are imaged by the imaging section 25 while receiving irradiation light from the light projecting section 24.

The light projecting unit 24 includes ring-shaped light emitters 2B and 29 that generate red light, green light, and blue light, respectively, based on the control signal from the processing unit 26, and irradiate the object to be inspected at different incident angles.
．． 30, and the substrate 20S,
Light is projected onto 20T, and an image of the reflected light is obtained by the imaging section 25 and converted into an electrical signal. In the case of this embodiment, each of the light emitting bodies 2B and 29.30 has a structure in which a white light source is covered with colored transparent plates of red, green, and blue. If so, it is not limited to this configuration, but three ring-shaped color fluorescent lamps (red, green,
blue) or three ring-shaped neon tubes (red).

green, blue) can also be used.

Further, this light projecting unit 24 can illuminate the substrates 20S and 2O under its illumination.
In order to make it possible to detect information regarding the components on the T (part number, polarity, color code, etc.) and board pattern information (various marks, etc.), each light emitting body 2B, 29.3
It is designed so that when the light of each hue emitted by 0 is mixed, it becomes completely white light. That is, each light emitting body 2B, 2
9.30 is constituted by a light emitting body that emits light in a red light spectrum, a green light spectrum, and a blue light spectrum, each having a emission energy distribution with respect to wavelength such that white light is produced by color mixing, and each of the light emitters 28, 29.30 The imaging controller 31 is capable of adjusting the amount of light of each hue so that the red, green, and blue lights emitted from the light are mixed to form white light.

Next, the imaging unit 25 includes a color television camera 32 located above the light projecting unit 24, and
The reflected light from the 3 or 20T is converted into three primary color signals R, G, and B by the color television camera 32 and supplied to the processing section 26.

The processing section 26 includes an A/D conversion section 33. Memory 38° Teaching table 359 Image processing unit 34° Judgment unit 36. X
, Y table controller 37° imaging controller 31
．． CRT display section 41. Printer 42. Keyboard 40.
Floppy disk device 43. It consists of a control unit (CPU) 39, etc., and when in teaching mode,
The mounting position of each component 21S from the reference board 203.

In addition to detecting the type and mounting direction of the mounted components and the inspection area, the color signals R, G, and
B is processed and each hue pattern of red, green, and blue is detected in the inspection area of each component 21S having a good soldering condition, characteristic parameters are generated, and a determination data file is created. Furthermore, in the inspection mode, the processing unit 26 outputs color signals R and G for the substrate to be inspected 20T.

B is processed, similar hue patterns are detected in the inspection area of each component 21T on the board, and feature parameters are generated;
Create a data file to be inspected. Then, by comparing this inspected data file and the judgment data file,
From this comparison result, a predetermined component 21 on the board to be inspected 2OT is selected.
To automatically determine whether a soldered part is good or bad based on T.

The A/D conversion section 33 configuring the processing section 26 is connected to the imaging section 2.
When color signals R, C, and B are supplied from the controller 5, they are converted into analog and digital signals and output to the controller 39. The memory 38 includes a RAM and the like, and is used as a work area for the control section 39. The image processing section 34 performs image processing on the image data supplied via the control section 39 to create the above-mentioned inspected data file and judgment data file, and supplies these to the control section 39 and the judgment section 36.

The teaching table 35 is connected to the control unit 3 during teaching.
When the judgment data file is supplied from the control unit 9, it is stored, and when the control unit 39 outputs a transfer request during inspection, the judgment data file is read out in response to this request and sent to the control unit 39 and the judgment unit. 36 etc.

The determination unit 36 compares the determination data file supplied from the control unit 39 at the time of inspection with the data file to be inspected transferred from the image processing unit 34, and determines the quality of the board 2 to be inspected.
At 0T, it is determined whether the soldering condition is good or not, and the determination result is output to the control section 39.

The imaging controller 31 includes an interface for connecting the control section 39 with the light projecting section 24 and the imaging section 25, and controls each light emitting body 28 of the light projecting section 24 based on the output of the control section 39.
, 29 and 30, and maintains mutual balance between the hue light outputs of the color television camera 32 of the imaging section 25.

The X, Y table controller 37 includes a control section 39 and the
It includes an interface for connecting the axis table section 22 and the Y-axis table section 23, and controls the X-axis table section 22 and the Y-axis table section 23 based on the output of the control section 39.

The CRT display section 41 is equipped with a cathode ray tube (CRT), and when image data, judgment results, key manual data, etc. are supplied from the control section 39, they are displayed on the screen. When the printer 42 is supplied with the determination result etc. from the control unit 39, it prints it out in a predetermined format. Keyboard 40 provides operation information and reference board 2
This keyboard 40 is equipped with various keys necessary for inputting data related to 0S and inspection standard 20T.
Information, data, etc. input from the control unit 39 are supplied to the control unit 39.

The control unit 39 includes a microprocessor, etc.
The operations in teaching and inspection are controlled according to the procedure described later.

FIG. 6 shows another example of application of the present invention, in which two light emitters are used as the light projector 24, namely, a light emitter 29 that generates blue light and a light emitter 30 that generates green light. ing. In this case, a red fluorescent agent that is excited by green light or blue light is used as the fluorescent agent applied to the substrates 2O3 and 20T, but a light emitting body that emits red light and a blue light source are used as the light projecting section 24. When using a luminescent material that emits , a green fluorescent agent that is excited by blue light is used.

FIG. 7 shows still another example of application of this invention,
One light emitter 49 that generates monochromatic light is used as the light projector 24. In this case, if the monochromatic light is white light,
As the fluorescent agent applied to the substrates 2O3 and 20T, a red fluorescent agent or a green fluorescent agent is used, a red fluorescent agent is used for green light, and a green fluorescent agent is used for blue light.

Note that when the white light hits the red fluorescent agent, green excitation light is generated, and when the white light hits the green fluorescent agent, blue excitation light is generated.

Next, the operation of the embodiment shown in FIG. 2 will be explained.

First, when inspecting a new substrate to be inspected 20T, the control section 39 controls each section of the apparatus to execute teaching, turns on the light projecting section 24 (the most image section 25), and also processes the imaging conditions and data. Set the conditions.Next, when the reference substrate 20S is set on the Y-axis table section 23, the control section 39
After controlling the X-axis table section 22 and the Y-axis table section 23 to position the reference inspection board 20S, the imaging section 25
The reference substrate 20S is imaged.

The color signal R1G of the three primary colors obtained by this imaging operation,
B is A/D converted by the A/D converter 33, and the conversion result is stored in the memory 38 in real time.

Next, the control section 39 causes the image data corresponding to each hue to be transferred from the memory 38 to the image processing section 34, and the image processing section 34 converts the image data of each hue into binary values using an appropriate threshold value for each hue. to detect red, green, and blue patterns. Further, the control unit 39 controls the image processing unit 34
is controlled, and each part (
Check the brightness of each part 21S (poles, etc.)
Identify the position of the electrode and the position of the polarity mark.

Thereafter, the control unit 39 creates a determination data file necessary for inspecting the board to be inspected 20T based on each of the hue patterns and the identification results, stores this in the teaching table 35, and then , end teaching.

Next, when shifting to the inspection mode, the control unit 39 takes in the date data of the day and the ID number (identification number) of the board to be inspected 20T from the teaching table 35 and the keyboard 40, and reads out the judgment data file from the teaching table 35. , and supplies this to the determination section 36.

Thereafter, the control section 39 checks whether the substrate to be inspected 20T is set on the Y-axis table section 23 after setting the imaging conditions and data processing conditions.

If set, the control unit 39 causes the image processing unit 34 to sequentially detect each hue pattern and identify the electrodes and polarity marks, as described above, and then compares each hue pattern with the above identification results. Create a data file to be inspected based on this. Next, the control unit 39 transfers the inspection data file to the determination unit 36, compares the inspection data file with the determination data file, and compares the inspection target data file with the determination data file.
The quality of soldering is determined for a predetermined component 21T on T, and the determination results are supplied to the CR7 display section 41 and printer 42 to display and print them out.

<Effects of the Invention> As described above, the present invention applies a fluorescent agent at least around the soldering area of a mounted component, and excites the light by shining light from a ring-shaped light emitter onto the surface coated with the fluorescent agent. The secondary illumination light generated by the excitation light is applied to the surface of the soldering area, and the reflected light image is drawn. Therefore, even if the surface of the soldering area is steep, the secondary illumination light generated by the excitation light is Since the illumination light is reflected from the steep slope and a reflected light image is generated, it is possible to automatically inspect all soldering parts regardless of the angle of the surface of the soldering part, which is a remarkable achievement of the purpose of the invention. It has a great effect.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the principle of this invention, FIG. 2 is an explanatory diagram showing the overall configuration of a board inspection device to which this invention is applied,
FIG. 3 is a perspective view showing the manufacturing process of the substrate, FIGS. 4 and 5 are plan views showing the fluorescent agent coated surface, and FIGS. 6 and 7 are explanatory views showing other application examples of the present invention. , FIG. 8 is a diagram explaining the principle of a conventional automatic inspection device, and FIGS. 9 and 10 are diagrams explaining the principle of the automatic inspection device. 20S, 2QT...Substrate 21S, 21T...Parts 17, 2B, 29.30.49...Light emitter 18.
... Soldering part 50 ... Fluorescent agent coated surface

Claims (1)

[Claims] A ring-shaped light emitter irradiates a mounted component on a board with light, captures an image of the light reflected from the surface of the soldering area, and inspects the properties of the soldering area from the imaged pattern. A board inspection method comprising: coating the surface of the board with a fluorescent agent at least around the soldering area of the mounted components; and applying light from the ring-shaped light emitter to the surface coated with the fluorescent agent. 1. A method for inspecting a board, which comprises: exciting light using the excitation light, applying secondary illumination light from the excitation light to the surface of a soldering area, and capturing an image of the reflected light.