JPH0252246A - X-ray inspection device - Google Patents

Abstract

PURPOSE:To enable nondestructive inspection by X rays and the outward appearance inspection for a object by arranging a camera for the outward appearance inspection successively together with an X-ray camera. CONSTITUTION:The object 20 is arranged between the X-ray tube 11 of an X-ray generation device and an image sensor 40 as the X-ray camera for X-ray radiography to perform the X-ray radiography. Further, a vidicon 300 is fixed on one flank side of the image sensor 40 as the camera for the outward appearance inspection and a fiber lighting system 304 for irradiating the object 20 with light from a light source outside the device so as to radiograph an outward appearance image of the subject 200 by the vidicon 300 is arranged adjacently to the image sensor 40. Further, mirrors 302 and 303 which have mirror surfaces slantingly upward and downward at 45 deg. are arranged right below the vidicon 300 so as to guide the reflected light of the illumination light from the object 20 to the vidicon 300. Consequently, the nondestructive inspection of the object is performed by observing the X-ray image and a defect place is grasped by observing an outward appearance shape.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an X-ray inspection apparatus that non-destructively inspects objects such as electronic circuit boards using X-rays.

(Prior Art) This type of X-ray inspection device places a subject between an X-ray source and an X-ray camera, and emits X-rays from the X-ray source toward the subject. It is composed of

The X-rays that have passed through the object are input to an X-ray TV camera, which converts the transmitted X-ray image into an optical image, which is then photographed by the camera and converted into an electrical signal, which displays the object image on a monitor. For example, if the subject is an electronic circuit board,
Since a plurality of electronic components such as ICs are mounted on this electronic circuit board, this electronic circuit board is supported on an X-Y table, and the position of the subject can be varied by table control. I am trying to image the parts.

(Problems to be Solved by the Invention) The above-mentioned X-ray inspection device converts the X-ray transmitted image of the subject into an image, so it is advantageous in that it allows non-destructive observation of images that reflect the internal structure of the subject. Perhaps because the X-ray exposure dose was set with emphasis on internal structure inspection, this X-ray inspection system did not clearly show the outline of the object, and plastics and other objects were not reflected in the X-ray image at all.

By the way, if a large number of components are mounted on the board-E, such as in the case of recent high-density electronic circuit boards, etc., there may be cases where components are inserted incorrectly, ICs are mounted in the opposite direction, or components are It was difficult to detect defects by visual inspection, such as non-mounted parts, by visual inspection.

Additionally, as mentioned above, there are parts of the X-ray image that do not reflect the external lines such as the outline of the part, so although the details of the defect can be observed from the X-ray image, it is sometimes difficult to recognize the defect location. .

Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide an X-ray inspection apparatus that is capable of not only non-destructive inspection using X-rays but also external inspection of a subject.

[Structure of the Invention] (Means for Solving the Problems) The present invention irradiates an object with X-rays from an In an X-ray inspection apparatus for destructive inspection, in addition to the above-mentioned X-ray images, an external image of a subject is obtained for inspection.

Here, it is possible to configure the sphere so that the distance between both the X-ray image camera and the external image camera and the subject position can be varied, and furthermore, the external image can be superimposed on the X-ray image and displayed on the monitor. can.

(Function) In the present invention, a camera for inspecting the external appearance of the object is installed in parallel with an X-ray camera, and an image reflecting the internal structure of the object is taken by the X-ray camera, while an image reflecting the external structure of the object is taken by the X-ray camera. A reflected image can be photographed using a camera for visual inspection.

Therefore, non-destructive inspection of the object can be performed by observing the X-ray image, and the defective location can be easily determined by observing the external image.

Furthermore, by observing the exterior image of the subject, for example, when the subject is an electronic circuit board, it is possible to check whether the wrong IC has been inserted, whether the IC is mounted correctly or defectively, and whether parts that should have been placed are missing. Mounting can also be inspected at a predetermined imaging magnification, which improves inspection accuracy and inspection speed compared to conventional visual inspection of the actual size, even for highly dense boards. The burden on the worker can be greatly reduced.

The above two types of images can be displayed in various ways, but it is most preferable to display both images superimposed, and in this case, the imaging magnification of both images should be the same. Although it is necessary to do so, it is preferable that the positions of both cameras can be moved relative to the subject position so that the desired photographic magnification can be obtained. In addition, it may be displayed in a divided manner on one screen.

(Example) The present invention will be described below as a non-destructive testing device for electronic circuit boards.
An embodiment applied to a line inspection device will be specifically described with reference to the drawings.

As shown in FIG. 2, this X-ray inspection apparatus has a subject 20 placed between an X-ray tube 11 of an XI1 generator 10 and an image sensor 40, which is an example of an X-ray camera that performs X-ray photography. In addition to being able to perform XwIA imaging, it is also possible to take an X-ray transmission image on an X-ray recording medium such as an instant film 200 that can be placed in front of the image sensor 4o.

The X-ray generating section 10 includes the X-ray tube 11 that generates X-rays.
and a high voltage generator 1 that applies a high voltage to this X-ray tube 11.
It is composed of 2. The X-ray tube 11 is equipped with a cathode filament and an anode opposite to the cathode filament in its internal vacuum, and when the filament is heated, thermionic electrons ejected are accelerated by a high DC voltage and collided with the vJiI pole. The kinetic energy of the thermoelectrons at this time is obtained as X-rays. In addition, the exposure amount of this X-ray is
By varying the tube voltage or filament current of 1,
It is possible to change it.

In addition, in the six embodiments in which a so-called minute focus X-ray source is adopted as the X-ray tube 11, the focal point size is 10
A microfocus X-ray source of 0 microns or less, preferably 15 microns or less is used. In order to obtain such a minute focus, it is sufficient to cause the thermoelectrons to collide with a minute region on the anode, which is the target of the thermoelectrons, and this can be achieved by focusing the target region using a focusing electrode or the like.

In this embodiment, the object 20 is an electronic circuit board on which electronic components such as ICs are mounted, and for example, an XY child table 0.
Support jig 1 placed on the x-y stage 109 of
A plurality of them are arranged in the X-Y stage 109 and can be set in the X-ray irradiation area by moving the X-Y stage 109.

In order to convert the above-mentioned X-ray image into an image,
The image sensor 40 for inputting lines is provided. In this embodiment, a vidicon is used as the image sensor 40, and the photoconductive surface of this vidicon, which is an X-ray input surface, is also sensitive to X-rays, and an electrical signal corresponding to the intensity of X-rays is sent. is output. Alternatively, the input surface of a vidicon for detecting visible light may be coated with fluorescent paint that is sensitive to X-rays. In addition, the input surface of the business controller as shown above is
For example, it is covered with an aluminum plate to block visible light.

For example, a variable gain amplifier 50 is provided downstream of the image sensor 40, and is configured to amplify and output the electrical signal with a gain determined to obtain an optimal image.

Further, an image processing section 60 receives the output of the amplifier 50.
The image processing unit 6o divides the electric signal into 256 levels or 51 levels for each predetermined level range.
The signal is binarized in two stages, and the binarized gradation signal is subjected to image processing such as edge enhancement and output.

Furthermore, a TV signal processing section 70 is provided after the image processing section 60.
A digital signal output from the image processing section 60 is converted into an analog signal, and further processed such as superimposing a synchronization signal to form a TV signal. Images can be displayed.

Further, in this embodiment, it is possible to take an X-ray image on film, and for this purpose, the instant film 200 can be placed on the mounting table 201. This instant film 200 has a negative and a positive sealed in two sheets of film, and at the same time, a liquid agent for developing and fixing is housed wrapped in a soft material. After photographing on this film, development and fixing are started by squeezing the liquid agent, and if it is a black and white film, the image can be recognized in about 15 seconds.

An example of this type of instant film is the film used in Polaroid cameras (trade name), which is also sensitive to the wavelength of X-rays.

Next, the characteristic configuration of the device of this embodiment will be explained.
As shown in FIG. 1, the camera is configured to include a vidicon 300 as an example of a camera for visual inspection. The vidicon 300 is fixed to one side of the image sensor 40, for example. In addition, in order to photograph the exterior image of the subject 20 with the vidicon 300, a light source that emits illumination light toward the subject 20 is arranged, and in the case of this embodiment,
A fiber illumination system 304 for irradiating light from a light source placed outside the device toward the subject 20 is placed next to the image sensor 40. Further, in order to guide the reflected light from the subject 20 due to the illumination light described in "2" to the vidicon 300, a surface having a mirror is installed at 45 directly below the vidicon 300.
° a first mirror 302 arranged to be inclined upward;
A second mirror 303 is provided directly below the image sensor 40 with a surface having a mirror tilted downward by 45 degrees, and reflects light reflected from the subject 20 to the first mirror 302 and guides it.

The second mirror 303 disposed in the X-ray irradiation area is made of a material with good X-ray transmittance, such as an aluminum plate. In addition, in this example, in the middle of the laser irradiation path,
Since the structure includes a mounting table 201 for the instant film 200, it is necessary to construct this with a transparent member or to drive it to retreat during laser irradiation.

The external image signal photographed by the vidicon 300 is processed into a TV signal by the 1゛V signal processing unit 312, and then superimposed on the TV signal of the X-ray image by the mixer 310 and displayed on the display. The image will be displayed at 80.

Here, the mixer 310, as shown in FIG.
The X-ray image video signal line and the external image video signal line are added via variable resistors VRI and VB2, respectively, and the variable resistors VR1 and VB2
The resistance values can be adjusted externally individually or in conjunction with each other.

In the X-ray inspection apparatus having the above configuration, the orthogonal axis direction on the two-dimensional plane on the X-Y table 100 is X.

When Y is the direction perpendicular to the X and Y axes, Z is the direction perpendicular to the X and Y axes.
In this embodiment, the X and Y positions of the subject 20 and the Z direction position of the instant film 200.

Z-direction position of the image sensor 40, Z position of the vidicon 300
The directional position is variable.

First, the support jig 110 that is fixedly supported on the X-Y stage], 09 Jr. and that supports the subject 20 will be described with reference to FIG.

The object 20 in this embodiment is an electronic circuit board as shown in FIG. By supporting the edge of the substrate 20 on the step surface 112, the substrate 20 can be placed parallel to the X-Y stage 109 and , a plurality of substrates 20 can be supported by partitioning with rods 114.

Next, a Z-direction adjustment machine M1 that changes the height of the instant film 200 and the image sensor 40 in the Z-direction is provided.
30 will be explained with reference to FIG.

As shown in the figure, a ball screw 131 is provided along the Z direction, and an idle pulley 132 is fixed to one end of the ball screw 131.
By passing a timing belt 135 around a drive pulley 134 fixed to the output shaft of a motor 133, the ball screw 131 is driven to rotate.

Further, the mounting table 201 for the image sensor 40 and the instant film 200 is supported by a Z-direction kite (not shown), and has a nut 1 screwed into the ball screw 131.
By fixing the ~ section 136, the height can be varied in two directions. Note that the vidicon 300 and the fiber illumination system 3
04 is adapted to move in the Z direction along with the image sensor 40.

Next, the effect will be explained.

In this embodiment, as shown in FIG.
0 is mounted on the support jig 110, and an X-ray inspection is performed. First, the leftmost subject 20 on the support jig 110 is set as the Xll irradiation area, and the position information is sequentially read out according to the pre-programmed flowchart. Execution control is performed, and then the second coordinate, third coordinate, etc. are automatically set to subject 2.
0 x.

By variably controlling the Y position and imaging magnification, both examinations can be performed continuously.

First, when performing an XIl inspection on the first subject 20 of an inspection lot, teaching of the imaging position and imaging magnification is performed. In this example, the shooting magnification is set at the distance shown in Figure 2!
1 or fixed, so the distance from the subject 20 to the image sensor 4 is
Z direction adjustment i#11.30 without mentioning the distance 12 to 0
This is done by varying the

After the above initial settings are completed, Xll is emitted from the X-ray tube 11 toward the subject 20. Note that at this time, the illumination from the fiber illumination system 304 is turned on, and photographing by the vidicon 300 is also performed.

First, X-ray photography will be explained. X-rays that have passed through the subject 20 are input to the image sensor 4o, where an X-ray transmitted image is photographed by the image sensor 4o.

At this time, in this embodiment, the X-ray tube 1, which is an X-ray source with a minute focus,
1, a clear X-ray image without blur can be projected onto the photoconductive surface of the image sensor 40.

That is, as shown in FIG. 6(b), if the focal point is not minute, in addition to the original transmitted image A1 of the object, a blurred image A2, which is caused by the large focal point, will occur, or if
As shown in a), in the case of a minute focus, only the transmitted X-ray image of the subject 20 will be incident on the image sensor 40, so a clear image without image blurring can be obtained.

The image sensor 40 outputs an electrical signal corresponding to the detected light intensity, and this electrical signal is amplified by the amplifier 50 and then input to the image processing section 60 .

The image processing unit 60 converts the analog electrical signals into 256,512
The digital signal is binarized into gradations such as steps, and various processes are executed at this digital signal stage.

Thereafter, this digital signal is input to the subsequent TV signal processing section 70, where it is converted into analog and processed into a TV signal on which a synchronization signal etc. are superimposed, and this T'V
By displaying an image on the display 80 based on the signal, an X-ray transmitted image of the subject 20 is converted into an image.

In addition, when using a conventional X-ray source with a large focus as shown in Fig. 6(b), parallel X-rays are emitted from this large focus, so X-ray fluorescence multiplier tubes, etc. It would have been impossible to perform X-ray photography without using something with a large input area, but since this example uses an X-ray tube 11 with a microfocus, the image is similar to that of a vidicon, etc., where the input surface has a small aperture of several inches. sensor 4
It can be adopted as 0. In addition, even with such a small-diameter input surface, it is possible to scan electronic components by moving the X and Y positions of the subject 20 or by increasing the imaging magnification of the X-ray image as described above. It becomes possible to photograph the whole or part of it as desired. Furthermore, an X-ray fluorescence multiplier tube is extremely expensive compared to a vidicon, and this embodiment is advantageous in that the apparatus can be made inexpensive.

Next, the appearance inspection of the subject 20 using visible light that is performed simultaneously with the collection of the X-ray images will be explained. 1. The illumination light from the fiber illumination system 304 is reflected by the subject 20, and this reflected light is 2 mirror 303. An image will be formed on the human power surface of the vidicon 300 via the first mirror 302. Here, this illumination light is reflected according to the reflection coefficient specific to the material within the object, and is guided to the vidicon 300 by reflected light from all objects within the illumination light irradiation range, regardless of its X-ray characteristics. .

And, the subject 20 photographed with this Vidicon 300
The external image signal is converted into a TV signal by the TV signal processing section 31-2, and is input to the mixer 310.

In the mixer 310, the dividing ratio for the X-ray image TV signal and the exterior image TV signal is set according to the resistance values of variable resistors VR1 and VB2 which are set in advance from the outside. Both signals are weighted and added according to the pressure ratio. Since the test is usually based on an X-ray image, the weighting of the X-ray image TV signal is increased (the resistance value is lowered), and both signals are added.

By displaying an image on the display 80 based on the T''V signal processed by the mixer 310 in this way, an X-ray image and an external image of the same region of interest of the same subject are displayed in a superimposed manner. .

As a result, by increasing the observation length of the image, it is possible to perform a non-destructive inspection that reflects the internal structure of the subject 20 using the X-ray image, and since the outline line can be recognized from the external image, it is possible to identify the location. It is possible to easily recognize whether a defect exists.

In addition, by observing the external image, it is possible to inspect objects that are difficult to observe with X-ray images, such as good or bad IC mounting orientation, incorrectly inserted parts, unmounted parts, etc.
Moreover, since the image is displayed at a predetermined magnification, the inspection can be performed reliably and easily. Also,
If the external appearance inspection is carried out independently, the above mixer 3
It is sufficient to change the variable resistance value in step 10 and display a weighted appearance image.

Next, the second subject 20 of the support jig 110 is set to the X-ray irradiation area, and X-ray photography and external photography are performed at each coordinate position in the same manner. i-0
The inspection will be performed on all the subjects 20 within. After completing the inspection of all the objects 20 in the support jig 110, replace the objects 20 in the jig 110 with new objects 20, and proceed with the X-ray inspection of the same type of objects 20. become. Note that it is also possible to set the instant film 200 and take an X-ray transmission image on the instant film 200, if necessary.

In this way, according to the device of this embodiment, it is possible to simultaneously perform a visual inspection in addition to a non-destructive inspection using an X-ray image, and since both images are displayed superimposed, it is possible to detect defects using an X-ray image. This makes it extremely easy to recognize the location where the defect occurs.

Note that the present invention is not limited to the above embodiments,
Various modifications are possible within the scope of the invention.

For example, the appearance inspection camera is not limited to the visible light camera as described above, but may also be an infrared camera that does not require an illumination system.

Alternatively, the illumination for X-ray exposure and exterior photography may be turned on alternately, and the display mode for both images may be -
Various modifications such as split display within the screen are possible. Furthermore, in the case where both images are displayed in a superimposed manner, a method such as displaying both images in different colors may be adopted so that the difference between the two images can be clearly understood.

Furthermore, the objects to which the X-ray inspection apparatus of the present invention can be applied are not limited to electronic circuit boards, but can be applied to various objects that require non-destructive inspection using X-rays.

[Effects of the Invention] As explained below, according to the present invention, in addition to X-ray inspection of a subject, external images of the same subject can be collected and displayed, and external images that are not reflected in X-ray images can be displayed. By doing so, it is possible to easily recognize the location where a defect occurs that can be detected by an X-ray image, and it is also possible to easily discover an appearance defect that cannot be detected by an X-ray image.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing an example of an X-ray camera and a photographing camera, and FIG. 2 is a schematic diagram illustrating an embodiment in which the present invention is not applied to an X-ray inspection device for an electronic circuit board. Explanatory drawings, Figure 3 is a plan view of the X-Y table for arranging the subject, Figure 4 is a schematic perspective view for explaining the subject and supporting jig, and Figure 5 is for X-rays. A schematic explanatory diagram for explaining the position variable mechanism of the camera, the visual inspection camera, and the X-ray recording medium. Figures 6 (a) and (b) explain the X-ray transmission image in the case of a minute focus and other cases. FIG. DESCRIPTION OF SYMBOLS 11... X-ray generation source, 20... Subject, 40... X-ray camera, 80... Display 300... Appearance inspection camera, 302.303... Mirror 304... lighting means. Agent Patent Attorney Inoue - (1 other person) Diagram (b) Alx) Nishi 1 Hif Sumishi ~ Napuonzu Table A2 , 4-pronged 1g

Claims (1)

[Scope of Claims] An X-ray inspection apparatus that non-destructively inspects a subject by exposing the subject to X-rays from an X-ray source and converting the X-ray image transmitted through the subject into an image, In addition, an X-ray inspection device is characterized in that it obtains and inspects an external image of a subject.