JPS6371642A - Substrate inspection method - Google Patents

Abstract

PURPOSE:To securely inspect a misalignment by obtaining the complete silhouette image of a component by applying preflux which contains an ultrasonic-ray excited fluorescent agent and picking up an image of the substrate where the component is mounted while the substrate is radiated with an ultrasonic ray. CONSTITUTION:Parameters (decision data) of respective components 13-1a-13-na on a reference printed board 10-1 which are obtained by picking up the image of the reference printed board 10-1 are compared with parameters (data to be inspected) of respective components 13-1b-13-nb on a printed board 10-2 to be inspected which are obtained by picking up the image of the printed board 10-2 to be inspected to detect the misalignments of those respective components (13-1b)-(13-nb) when they shift in position. In such a case, the board 11 is coated with the preflux 45 which contains the ultraviolet-ray excited fluorescent agent before the components 13-1a-13-na are mounted on the raw board 11 to obtain the color of the raw board 11 and the accurate silhouette image of the respective components 13-1a-13-na.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for inspecting a board, which processes data obtained by imaging a board to inspect components on the board.

(Prior art) When mounting various chip components such as resistors and semiconductor elements on a printed circuit board using the own Sh mount device, it is possible that the components may not be mounted according to the mount data after mounting. be.

For this reason, when using such automatic mounting equipment, it is necessary to jack the printed circuit board after mounting and make sure that the correct deep parts are mounted at the correct positions and in the correct orientation (position and direction) on the printed circuit board. Whether there is
It is also necessary to inspect whether or not it has fallen off.

However, if such an inspection is carried out by visual inspection using a nest as in the past, there are problems in that the occurrence of inspection errors cannot be completely eliminated and the inspection speed cannot be increased.

Therefore, in recent years, manufacturers have proposed various automatic inspection devices for printed circuit boards that can automatically perform this type of inspection.

FIG. 7 is a block diagram showing an example of such an automatic inspection device.

The automatic inspection device shown in this figure includes a TV camera 3 that images a printed circuit board 2-2 to be inspected on which a component 1 is mounted, and data input from a keyboard 8, which serves as a reference board as shown in FIG. Data regarding the type, etc. of the reference printed circuit board 2-1, data regarding the type, distribution position, mounting posture, shape, etc. of each component 1 mounted on this reference printed circuit board 2-1, and inspection of each of these components 1. A storage unit 4 stores information (data) related to processing procedures, etc., and the information stored in this storage unit 4 is compared with the information shown by the image from the TV camera 3, and the printed circuit board to be inspected 2- Whether all parts 1 are on 2,
It also includes a determination circuit 5 that determines whether or not these parts 1 are misaligned or not, and a monitor 6 that displays or prints out the determination results of this determination circuit 50.

(Problem to be Solved by the Invention) By the way, some of the components 1 inspected by this type of automatic inspection device have a color similar to that of the board, and for such components 1, the signal level of the component part and There is a problem in that the signal level of the background part becomes almost the same, and even if this part falls off or is misaligned, it cannot be detected.

Therefore, on the base board of the printed standard 2-2 to be inspected,
As shown in FIGS. 9(A) and 9(B), a resist 50 containing an ultraviolet-excited fluorescent agent is applied to form a resist layer 52, and when this is illuminated with an ultraviolet light source, it is possible to see that it is mounted on this base substrate. A device that allows a silhouette image of the component 1 to be obtained has already been developed, but in such a device, the resist layer 52 is not formed on the land 51 as shown in FIG. There was a problem that a complete silhouette image could not be obtained.

The present invention is based on the above-mentioned circumstances and can obtain a complete silhouette image of a component, thereby making it possible to obtain a complete silhouette image of a component, even when the color of the component and the color of the board are the same or similar, even for all components. It is an object of the present invention to provide a method for inspecting a board by which it is possible to inspect whether the board has fallen off or is misaligned.

(Means for Solving the Problems) In order to solve the above problems, a board inspection method according to the present invention is a board inspection method in which data obtained by imaging a board is processed to inspect components on the board. After a preflux containing an ultraviolet-excited fluorescent agent is applied, the board on which components are mounted is exposed to ultraviolet light and imaged.
The present invention is characterized in that the parts are inspected by distinguishing between fluorescent parts and non-fluorescent parts of the image bundle.

(Embodiment) FIG. 1 is a block diagram showing an example of a board inspection apparatus to which an embodiment of the root inspection method according to the present invention is applied.

The board inspection equipment d shown in this figure has an X-Y-table section 14.
, an illumination section 12, an imaging section 15, and a processing section 16, and each component 13-1 on the reference printed circuit board 10-1 obtained by carrying the reference printed circuit board 10-1.
Each component 1 on the printed circuit board to be inspected 10-2 obtained by using the parameters (judgment data) of a to l3-na and the printed standard to be inspected 10-2: 3-1b to l3
By comparing the parts 13-1b-nb with the individual parts 13-1b-nb (data to be inspected), it is detected if each of these parts 13-1b-nb has fallen off or is misaligned.

X-Y table P! S14 is mentioned above! i! A pulse motor 17゜18 that operates based on a control signal from the buried section 16.
, an X-Y table 19 that is moved in the X-axis direction and Y-axis direction by each of these pulse motors 17 and 18; When each t, 4110-1.10-2 is placed, each i, S&10-1.10-2 is fixed on the X-Y table 19 in accordance with the control signal output from the processing section 16. It is equipped with a chuck binding mechanism 20,
Each of the It plates 10-1 and 10-2 fixed by the chuck mechanism 20 is photographed by the imaging part 15 while being illuminated by the illumination part 12.

In this case, the reference printed circuit board 10-1 is manufactured as described below.

First, a bare board 11 as shown in FIG. 2A is created by performing etching, resist processing, drilling, etc. on a raw board with copper foil covered on both sides (M1 = one side). Next, a preflux 45 containing an ultraviolet-excited fluorescent agent is applied to the entire surface of this base substrate 17 to form a fluorescent layer 46, and then
As shown in FIG. 2(B), the component 13 is placed on the fluorescent layer 46.
An adhesive 47 containing an ultraviolet-excited fluorescent agent and a solder paste 48 containing an ultraviolet-excited fluorescent agent are applied to the portions where -1a to l3-na are to be mounted. And Figure 2 (C)
As shown in the figure, the reference printed circuit board 10-1 has components 13-1a to 13-na mounted thereon.

Further, the printed circuit board 10-2 to be inspected is also manufactured in the same procedure as the reference printed circuit board 10-1.

The illumination section 12 also includes an ultraviolet light source (black light source) 7 that is controlled on/off based on a control signal from the processing section 16, and an ultraviolet light source 7 that directs the ultraviolet light emitted from the ultraviolet light source 7 to the X-Y table section 1. The respective substrates 10-1 are irradiated from the side 4.
．． 10-2, and a dichroic mirror 8 that transmits the fluorescent light (chromic light) emitted by the fluorescent layer 46 on each of the substrates 10-1 and i-2. The generated fluorescence is supplied to the imaging section 15.

The imaging section 15 includes a TV camera (monochrome TV camera) 21 provided above the illumination section 12, and this TV camera 2.
A fluorescence transmission filter 9 provided on the front surface of the lens 1 is provided, and from the light from each of the substrates 10-1 and 10-2, only fluorescence is selected by the fluorescence transmission filter 9, and this is converted into an electrical signal by the TV camera 21. (image signal) and supplied to the processing section 16.

In this case, as shown in FIG. 3 (Δ), each board 10-1.
Parts 13-1a to 13-na placed on 10-2
(or parts 13-1b to 13-nb), whether the color is brown, white or black, each of these parts 13-1a to 13-nb
Since the parts 13-na (or parts 13-1b to 13-nb) are illuminated with ultraviolet rays, all the light reflected by them becomes only ultraviolet rays and is completely cut off by the dichroic mirror 8 and the fluorescence transmission filter 9. .

On the other hand, since a fluorescent layer 46 is formed on the base substrate 11 on which each of these components 13-18 to 13-na (or components 13-1 b to 13-nb) is mounted, it is illuminated by ultraviolet rays. When the parts 1l on the fluorescent layer 46
-1a~1:3-na (Ma1= is part 13-1b~
13-nb) emits fluorescence in areas other than the area on which it is placed. Since this fluorescence is colorimetric light, it is transmitted to the dichroic mirror 8 and the fluorescence transmission filter 9.
is transmitted sequentially and enters the TV camera 21. As a result, each of the substrates 10-1.1 can be viewed by this TV camera 21.
The image signal $1 obtained by transferring 0-2 is shown in Fig. 3 (B
), the signal level of the part where parts 13-1a to 13-na (or parts 1]-1b to 13-nb are present decreases, and the signal level of the background part thereof becomes high.

Further, in the teaching mode, the processing section 16 controls the reference printed circuit board 10 from the image signal (image signal of the reference printed circuit board 10-1) supplied from the image carrier section 15.
-1 extracts the parameters of each component 13-1a to l3-na to create a judgment data file, and when in the inspection mode, the image signal (
Each component 13-1 on the printed circuit board 10-2 to be inspected is
A data file to be inspected is created by extracting the parameters of b to l3-nb, and this data file to be inspected is compared with the judgment data file, and each of the parts 13-1b to l3-nb is extracted from the comparison result. The A/Da conversion section 23, the memory 24, the teaching table 25, and the image processing section 2
6, the determination section 22, the X-Y stage controller 2, the transport controller 38, the CRT display 28, the printer 29, the keyboard 3o, and the υ control section 1 (Cl"
'tJ)31.

When the A/D converter 23 is supplied with an image signal from the image pickup unit 15, it converts the image signal into an A/D converter (analog/digital converter) to create image data, which is then sent to the controller 31.
supply to

Further, the memory 24 includes a RAM (random access memory), etc., and is configured by the control unit 3.
It is used as a work area.

Further, the image processing section 26 is configured to, when supplied with image data via the control section 31, binarize this image data and extract the area parameters and shape parameters of each component image. Each parameter obtained is supplied to the control section 31 and the determination section 22.

Further, the teaching table 25 is equipped with a floppy disk device, etc., and when supplied with a judgment data file etc. from the control section 31 in the old teaching mode,
Memorize this and use the above a, 1111 at the time of inspection.
When the first unit 31 outputs a transfer request, it reads out the determination data file etc. in response to this request and sends it to the control unit 31.
Supply to etc.

Further, the determination unit 22 determines whether the front 22! I 111
When the determination data file is supplied from the section 31 and the inspection data is supplied from the image processing section 26, these are compared and determined to determine the presence or absence of the parts 13-1b to 13-nb.
It is configured to determine the position δ deviation, etc., and the result of this determination is supplied to the control section 31.

The imaging controller 38 also includes an interface for connecting the υ control section 31 to the illumination section 12 and the image carrier section 15, and based on the output of the control section 31, the illumination section 12 and the image carrier section 15 and control.

Further, the X-Y stage controller 27 is connected to the control section 31.
and the X-Y table section 14, and the aili 1
Based on the output of the 11 section 31, the X-Y tare section 14
wovl 110 'J le.

The CR7 display 28 is equipped with a cathode ray tube (CRT), and when image data, judgment results, key manual data, etc. are supplied from the control section 31 of @arrangement t, it is displayed on the screen.

Further, when the printer 29 is supplied with the determination result etc. from the control section 31, it prints it out in a predetermined format.

The keyboard 30 also stores operation information and data regarding the reference printed circuit board 10-1.
The keyboard 30 is equipped with various keys necessary for inputting data related to the parts 13-1a to 13-na on the keyboard 30, and information and data inputted from the keyboard 30 are supplied to the control unit 31. .

The control unit 31 includes a microprocessor and the like, and operates as described below.

First, when inspecting a new printed circuit board 10-2 to be inspected, the control unit 31 executes the teaching routine shown in the flowchart of FIG. 4(B) in step ST1 of the main flowchart as shown in FIG. 4(Δ). 32, and in step ST2 of this teaching routine 32, each part of the device is initialized and the image conditioning and data 5.
1! l! After the processing conditions are set, the reference printed circuit board 10-1 is held until it is placed on the XY table section 14 in step ST3.

Then, a reference printed circuit board 10 is placed on the X-Y table section 14.
-1 is placed, the control unit 31 performs the step ST3.
The process branches to step ST4, where the X-Y table section 14 is controlled to arrange the first imaging area of the reference printed circuit board 10-1 below the TV camera 21.

After this, the control unit 31 controls the TV camera 21 in step ST5.
The A/D converter 23 converts the image signal obtained by
At the same time, the Δ/[) conversion result (image data of the reference printed circuit board 10-1) is stored in the memory 24 in real time.

Next, the control unit 31 stores the memory 24 in step ST6.
The image data of the reference printed circuit board 10-1 is read out from , and is supplied to the image processing section 26 to be binarized, and in step ST7, each of the parts 13 1a to 13-ia ( 2≦i≦n) is extracted, and each component 13- is extracted from each of these component images.
Parameters such as position, shape, area, center of gravity, etc. of 1a to 13-ia are extracted.

Next, in step ST8, the v-control unit 31 creates determination data regarding each of the parts 13-1a to 13-ia from the parameters listed in ili'i.

After this, the control unit 31 controls each component 13-1 in step ST9.
It is checked whether judgment data have been obtained for all parts a to 13-ia, and the step S is continued until judgment data has been obtained for all parts 13-1a to 13-ia.
Steps T7 to ST9 are repeatedly executed.

Then, when the determination data for all of these parts 13-1a to 13-ia are obtained, the tlllE section 31 branches from step ST9 to step 5T10, where the entire image transfer area of the reference printed circuit board 10-1 is Check whether processing has been completed.

If there remains an unprocessed imaging area, the control unit 31 returns from step 5T10 to step ST4 and repeats the above-described operation.

Then, when the processing for all the image carrying areas is completed, the control unit 31 performs steps 5T10 to 5T11.
Here, the printed circuit board 10-2 to be inspected is determined from each determination data regarding each of the components 13-1a to 13-na.
After creating a judgment data file necessary for testing and storing it in the teaching table 25, this teaching routine is ended.

Further, when this teaching routine 32 is completed and the test mode is set, the control section 31 calls the test routine 34 shown in the flowchart of FIG. 4(C) at step 5T12 of the main flowchart. Teaching table 25 in step 5T13
It takes in the date data of the day and the ID number (identification number) of the printed circuit board 10 - 2 to be inspected from the keyboard 30 , reads out a determination data file from the teaching table 25 , and supplies it to the determination section 22 .

Next, the control section 31 holds the printed circuit board 10-2 to be inspected until it is placed on the X-Y table section 14 in step 5T14.

Then, the reference printed circuit board 1 is placed on the X-Y table section 14.
If 0-2 is loaded, the υj control unit 31
The process branches from T14 to step 5T15, where the X-Y table section 14 is controlled to place the first Wi image area of the print substrate to be inspected &10-2 below the TV camera 21.

Next, the control unit 31 controls the TV camera 2 in step 5T16.
The image signal obtained in step 1 is converted into A/D converter 23 by A/D converter 23.
Along with the D conversion, this A/D conversion result (image data of the printed circuit board 10-2 to be inspected) is stored in the memory 24 in real time.

Next, the control unit 31 stores the memory 2 in step 5T17.
The image data of the reference print base &10-2 is read out from 4 and supplied to the image processing ff126 to be binarized.

Next, t, lII [1 part 31 is converted into each part 13-1b to 13-ib from this 21ilI conversion process in step 5T18.
The parts images of parts 13-1b to 13-ib are extracted from these parts images, and parameters such as the scaled shape, area, and center of gravity of each part 13-1b to 13-ib are extracted, and based on these parameters, parts 13-1b to 13-ib are extracted. 13-ib to create test data for all of them.

Thereafter, in step 5T19, the control unit 31 transfers the inspection data to the determination unit 22, compares each determination data with each of the inspection target data, and determines the parts on the printed circuit board 10-2 to be inspected. 13-1b to 131b are missing,
In addition to determining whether or not positional deviation has occurred,
This determination result is stored in the memory 24.

Thereafter, the control unit 31 returns from step 5T20 to step 5T15, and sequentially executes the above-described processing for the remaining image carrying areas of the printed circuit board 10-2 to be inspected.

Then, when processing is completed for all imaging areas, 2
The 111tl11 unit 31 branches from step 5T20 to step 5T21, where it reads out the determination results for each of the parts 13-1b to 13-nb stored in the memory 24 and displays them on the CRT display 28, The image may be printed out from the printer 29.

As described above, in this embodiment, components 13-1a to 13-na (or components 13-1b
~ 13-nb) was applied on this base substrate 11, so that the color of the base substrate 11 and each component 13-ia ~ 13-na could be adjusted.
(or parts 13-1b to 13-nb).

Further, in the above embodiment, each substrate 10-1.10-2 is imaged by the TV camera 21, but as shown in FIG. -2 may be conveyed and imaged by the line sensor 41 at 11 fi. Of course, in this case as well, each of these substrates 10-1.
Since preflux containing an ultraviolet-excited fluorescent agent is applied on 10-2, the color of the base substrate 11 and the component 111 are
8 to 13-na (or parts 13-1b to 13-nb
) can obtain accurate silhouette images.

Furthermore, instead of the TV camera 21 and licenser 41, a phototransistor 43 with a photoelectric amplification core is used as shown in FIG. 6, and each substrate 10-1 is
．． While applying the ultraviolet beam onto 10-2, the ultraviolet beam is scanned in X-Y direction, and each substrate 10-1.10
-2 images may be obtained.

In this case, the ultraviolet beam IQ44 i,t, an ultraviolet light emitting laser (or an ultra-high pressure mercury lamp, etc.), a primary filter that filters the light obtained by this ultraviolet '12 light emitting laser, and a light beam that passes through this primary filter are used. light (ultraviolet light)
The ultraviolet light beam emitted from this condenser is scanned over each substrate 10-1 and 10-2, and the ultraviolet light beam is emitted from this condenser. Parts 13-1 a to 13-na (or parts 13-na) mounted on 10-1 and 10-2
1b to 13-nb) can be obtained.

Further, in the above-described embodiment, an ultraviolet-excited fluorescent agent is mixed in the preflux 45, but a monochromatic light-excited fluorescent agent may be mixed instead of the ultraviolet-excited fluorescent agent.

In this case, if the rS semi-printed circuit board 10-1 and the printed circuit board to be inspected 10-2 are illuminated with a monochromatic light source, the component 13-
Assuming that the back shadow parts of parts 1a to 13-na (13-1b to 13-nb) emit fluorescence, parts 13-1a to 13-
Since the light from the monochromatic light source is reflected by na (13-1b to 13-nb), if the light from these reference printed circuit boards 10-1 and to-be-inspected printed circuit boards 10-2 is color-identified, the parts 13 -1a ~ l3-na (13
-1b ~ 13-nb) body and this part 13-1
ff of a to l3-na (13-1b to 13-nb)
1K and the board marks on the reference printed circuit board 10-1 and the printed circuit board to be inspected 10-2 can be detected.

Further, instead of such an ultraviolet-excited fluorescent agent or a monochromatic light-excited fluorescent agent, a white-light excited fluorescent agent may be mixed into the preflux 45.

In this case, if the reference printed circuit board 10-1 and the inspected printed circuit board 10-2 are illuminated with a white light source, the parts 13
-1 a ~13-na <13-1 b ~13-nb
) The back shadow part of part 13-1a emits fluorescence, and part 13-1a
Since the light from the white light source is reflected by 13-na (13-1b to 13-nb), if the light from these reference printed circuit boards 10-1 and to-be-inspected printed circuit boards 10-2 is color-identified, Parts 13-1a to l3-na
(13-1b to l3-nb> body and this part 13
-1a to l3-na (13-1b to 13-nb) electrode and color code, and reference print 3;! m1°-1, the printed circuit board to be inspected, and the root marks on the board 10-2 can be detected.

(Effects of the Invention) As explained above, according to the present invention, even if the color of the component and the color of the board are the same or similar, all components can be inspected for falling off, misalignment, etc. Can be done.

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram showing a first embodiment of the present invention, FIGS. 2(A) to (C) are perspective views showing the manufacturing process of a printed circuit board in each embodiment, and FIG. 3(A) is the same. A schematic diagram showing an example of the position of component colors in the example, FIG. 3 (8) is the third
A waveform diagram showing an example of a layer image signal on line a in FIG.
Figure 4 (A) to (C) are the same collision! FIG. 5 is a circuit block diagram showing an example of a device for explaining the second embodiment of the present invention, and FIG. 8 is a front view showing an example of a reference printed circuit board used in this device. , No. 9
Figures (A) and (B) are perspective views for explaining other examples of conventional automatic inspection devices, respectively, and Figure 10 is a partially enlarged view of Figure 9 (B). 10-1... Reference printed circuit board, 10-2... Printed circuit board to be inspected, 12... Lighting section, 14... X-Y
Table section, 15... Recording section, 16... Processing section, 4
6.--Fluorescent layer. Patent applicant Tateishi Electric Co., Ltd. Patent attorney Tetsuji Iwakura (1 other person) Figure 3 (A) Figure 4 Cρ1 Procedural amendment December 16, 1988

Claims (1)

[Claims] In a board inspection method in which components on the board are inspected by processing data obtained by imaging the board, after a preflux containing an excitation fluorescent agent is applied, the board on which the components are mounted is exposed to light. A method for inspecting a board, which comprises inspecting the component by imaging the board and distinguishing between fluorescent and non-fluorescent parts of the image.