JPS62299707A - Inspecting instrument for package parts - Google Patents

Abstract

PURPOSE:To detect a parts with good contrast unless the reflectivity of a surface to be detected is uniform by detecting reflected light beam from a printed circuit board part and the parts through an optical mask formed light transmission parts and light cutoff part almost in a checkerboard shape. CONSTITUTION:The mounted printed circuit board P is irradiated with a slit type light beam l1 by an irradiating means (semiconductor laser 12, etc.). Then, a line sensor 17 which has plural photodetecting elements 17a arrayed detects reflected light l3 from the circuit board part R by the light beam irradiation and reflected light l2 from the top surface of the parts by each photodetecting element 17a alternately through a detecting means (image forming lens 15, etc.) and the optical mask 16 which have the light transmission parts 16a and 16b and light cutoff parts 16c and 16d arranged almost in a checkerboard pattern corresponding to the photodetecting elements 17a. Then, the sampling circuit of a signal processing circuit extracts and separates detection signals of the line sensor 17 by the photodetecting elements 17a alternately and the separated detection signals are compared mutually to judge the package state of the parts from the comparison result. Thus, the parts is detected with good contrast.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [(Already required)] The present invention irradiates a slit-shaped light beam onto a printed board on which components are mounted, and detects the reflected light with a line sensor. As a result, in a mounted component inspection device that inspects the mounting and condition of components, the reflected light from the board section of the printed board and the reflected light from the top surface of the component are transmitted to each of the line sensors through a substantially checkered optical mask. Detects each photodetector alternately,
By determining the mounting state of the above-mentioned components based on the results of comparing the detection signals, a simple optical system can be used even when the reflectance of the detection surface is not uniform. This makes it possible to inspect the mounting state of components with very good contrast.

[Industrial application field]

The present invention relates to a mounted component inspection apparatus that automatically optically inspects the mounting state (for example, presence or absence, positional shift, etc.) of electronic components (particularly chip components) mounted on a printed board.

Currently, with the miniaturization of semiconductor elements and other electronic components,
The density of printed circuit boards is increasing. As the number of printed circuit boards mounted with chip components increases, it is desired to automatically inspect the mounting state of these circuit boards. For this purpose, it is necessary to detect parts accurately and with good contrast.

[Conventional technology]

FIG. 6 shows an optical system related to a conventional mounted component inspection apparatus.

In the figure, the substrate portion R of the printed board P is cut using the optical cutting method.
Only the component Q at a predetermined height h above is detected. That is, while placing the printed board P on the stage 1 and moving it in the direction of arrow A, the semiconductor laser 2,
A slit-shaped light beam (hereinafter referred to as slit beam) 11 created by the pre-lens 3 and the cylindrical lens 4 is irradiated onto the printed board door obliquely from above. Then, only the reflected light 12 from a predetermined height h is imaged by a line sensor 6 such as a COD via an imaging lens 5. Based on the image obtained by setting the detection signal strength of the line sensor 6 to ``1'' when it is above a predetermined slice level and ``0'' when it is below a predetermined slice level, that is, an image in which only the component Q having the predetermined height h is distinguished from the others. , to inspect the implementation status.

[Problem that the invention seeks to solve]

In the conventional device described above, even if there is a component at the height h of interest, if the surface of this component is black, the reflected light may be weak and it may not be detected sufficiently. Even if a component is located at a location deviating from the height h, if there is a bright area around it, the light reflected from there may sometimes cause it to be detected as a predetermined component. Therefore,
For example, if you increase the sensitivity of the sensor to completely detect a black part, as shown in detection example (i) in Figure 7, not only the part body Q (black part) but also the bright electrode part P1 on the printed board door will be detected. Also, due to the wraparound of light from there,
It was detected that the level was higher than the slice level, and both were judged as "1", that is, as parts. On the other hand, the reflected light from the height of the board part R! , to detect parts other than the part as complete shadows. As shown in detection example (ii) in the same figure, the bright part of the part Q, the electrode part Q2, also receives light from there. Due to the wraparound, it was detected as a non-component part.

That is, the conventional device has a problem of poor contrast (S/N).

In view of the above problems, the present invention provides a mounted component inspection device that can detect components with good contrast (S/N) using an optical system with a simple configuration even if the reflectance of the detection surface is not uniform. The purpose is to provide.

[Means for solving problems]

According to the present invention, the respective reflected lights from the substrate part and components due to slit beam irradiation are transmitted to each light receiving element of a line sensor through an optical mask in which light transmitting parts and light blocking parts are arranged in a substantially checkered pattern. It is characterized by alternately detecting the signals, alternately extracting and separating the detection signals for each light-receiving element, and comparing the separated detection signals with each other to determine the mounting state of the components on the printed board. shall be.

[For production]

Generally, even if the component is black, the reflected light detected from the top surface of the component is stronger than the reflected light detected from the top of the board. Further, the reflected light that is directly detected from a bright part (for example, an electrode part) on the substrate part is stronger than the light that goes around from that part and is detected as reflected light from on the component. Similarly,
The reflected light that is directly detected from a bright part (for example, an electrode part) on a component is stronger than the light that comes around from that part and is detected as reflected light from the substrate. In this way, the intensity of each reflected light increases depending on whether a component is present or absent, regardless of the brightness of the detected surface on the printed board.

In addition, as mentioned above, the two detection signals obtained by alternately extracting and separating each light receiving element of the line sensor are one of the detection signals of the reflected light from the board part, and the other is the detection signal of the reflected light from the component. This is the detection signal.

Therefore, one of the intensities of these detection signals becomes larger depending on the intensities of the respective reflected lights described above.

Therefore, by comparing the above two detection signals and seeing which one is larger, it is possible to accurately determine whether the detected object is a component or a board, without being affected by the above-mentioned light wraparound. can be judged. In other words, the electrode part of the component may be mistakenly detected as the board part,
In addition, there is no possibility that the electrode portion on the substrate portion is mistakenly detected as a component, and component detection with very good contrast becomes possible.

Moreover, by using the optical mask mentioned above, it is possible to detect two reflected lights with one line sensor. There is no need for a beam subrifter or the like to separately supply the beam to the line sensor, making it possible to configure the optical system in a very simple manner.

〔Example〕

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

FIG. 1 is a configuration diagram showing a light irradiation means and a light detection means according to an embodiment of the present invention.

First, the light irradiation means is composed of a semiconductor laser 12, a collimating lens 13, and a cylindrical lens 14.
A printed board P placed on a stage 11 and moving in the direction of arrow A is irradiated with a slit beam 11 from diagonally above.

This slit beam 11 is obtained by converting a laser beam output from a semiconductor laser 12 into parallel light using a collimating lens 13, and further converting it into a slit-like beam using a cylindrical lens 14. Note that the direction of the optical cutting line formed on the printed board P by the slit beam 11 is perpendicular to the moving direction (arrow A) of the printed board P.

Next, the light detection means includes an imaging lens 15, an optical mask I
6 and line sensor (e.g. CCD line sensor, etc.)
17, reflected light from the printed board P due to irradiation with the pick-nod beam 21 (reflected light from the upper surface of the component Q having a predetermined height range!! 2, reflected light from the board portion R!, etc.) is detected from a direction different from the irradiation direction of the slit beam A.

The light receiving surface of the line sensor 17 is enlarged in FIG.
Shown below. As shown in the figure, the line sensor 17 has a configuration in which a plurality of light receiving elements (CCD, etc.) 17a having a rectangular light receiving surface are arranged in a line.

Furthermore, as shown in FIG. 1, the longitudinal direction (direction of arrow B) of the light receiving element 17a corresponds to the height direction of the component Q, and all the light receiving elements receive the above two reflected lights by the imaging lens 15. It is arranged so as to be located within the image formation plane of I12 and l.

The optical mask 16 is attached to the line sensor 1 in FIG.
7 is shown in the same figure. As shown in the figure, the optical mask 16 includes light transmitting parts 16a and 16b and a light blocking part 1.
6C116d and each light receiving element 17a of the line sensor 17.
They are formed alternately in accordance with the pitch of the line sensor 17 in a substantially checkered pattern, and are arranged in close contact with the light receiving surface of the line sensor 17 as shown in FIG. In the state where they are closely arranged in this way, among the light transmitting parts 16a and 16b,
The light transmitting portion 16a, which has a longer rectangular shape, reflects light from the top surface of the component Q having a predetermined height range! ! The other light transmitting portion 16b, which has a substantially square shape, is located at a position where only the reflected light l from the substrate portion R is transmitted. Therefore, the two reflected lights 1z and I13 are transmitted to the line sensor 1 by passing through the optical mask 16.
The light is detected separately and alternately by each of the seven light receiving elements 17a. These detection signals are processed by a signal processing circuit (fourth
), the signals are taken out alternately for each light-receiving element 17a and separated into a detection signal for the component Q and a detection signal for the substrate R.

The optical mask 16 can be created by depositing chromium or the like on a transparent glass plate to form an opaque film in accordance with the pattern of the light blocking parts 16c and 16d.

Here, an example of detection of reflected light at each position on the printed board door using the optical system will be explained based on FIG. 3.

First, when the slit beam 11 is irradiated onto the component Q as shown in FIG. Therefore, the intensity of the detection signal of the component Q obtained by the line sensor 17 through the light transmitting part 16a is
It is thicker than the detection signal of the substrate part R obtained through the light transmitting part 16b. Also, the reflected light 1t from a bright part on the component Q (for example, the electrode part Q shown in FIG. 7) is Even in the case where the light is detected through the transmission part 16a and a part of the reflected light is detected through the other light transmission part 16b, the directly reflected light is stronger. The intensity of the detection signal for component Q is thicker than the detection signal for board portion R.

Furthermore, as shown in Figure 3), if the slit beam lI comes off the part Q and is irradiated onto the electrode part P on the substrate part R, even if part of the reflected light from the electrode part PI is Even if the part wraps around and is detected through the light transmitting part 16a,
Since the linear reflected light l is still stronger, the intensity of the detection signal for the substrate portion R is greater than the intensity of the detection signal for the component Q.

Also, as shown in Figure 3 (TC), even if the substrate portion R is made of dark resist, the reflected light has a certain degree of intensity! .

Therefore, the intensity of the detection signal for the substrate portion R is greater than the intensity of the detection signal for the component Q.

From the above, when the slit beam 11 is irradiated onto the top surface of the component Q, the detection signal of the component Q will have a greater intensity than the detection signal of the substrate R even if the reflectance of that surface is not uniform. On the other hand, when the slit beam 11 is not irradiated onto the component Q but is irradiated only onto the substrate portion R, the detection signal from the substrate portion R is not uniform even if the reflectance there is not uniform. It has greater strength than the Q detection signal. Therefore,
By looking at which of these two detection signals is larger, it can be accurately determined whether the object to be detected is the component Q or the board R.

Next, a signal processing circuit according to this embodiment for performing these signal processes will be explained based on FIG. 4.

In the figure, the drive circuit 18 includes the line sensor 17
is driven, and its detection signal is extracted and sent to the sample circuit 19. The sample circuit 19 alternately samples the detection signal for each light receiving element 17a of the line sensor 17,
Detection signal of component Q (component signal) and detection signal of board part R (
(board part signal) and output separately. Next, the gains of the component signal and the substrate signal are respectively adjusted appropriately by amplifiers 20 and 21, and then applied to the 10 and - input terminals of the comparator 22. The comparator 22 compares the two input signals and binarizes the comparison result into "1" and "1".
0" is output.

In the above circuit, when the component signal is larger than the substrate signal, that is, when the component Q is detected, the output of the comparator 22 becomes "1".

On the other hand, when the board part signal is larger than the component signal, that is, when only the board part R is detected, the output of the comparator 22 becomes rOJ. If there is an electrode part Q,,P on the component Q or the substrate part R as shown in FIG. 7, and light wraps around from that part, sample circuit 1
The detection example (i
) and (ii), but the results obtained by comparing them with each other and binarizing them with the comparator 22 are completely free from the effects of the light looping, and each part is Correctly corresponding values "1" and "0" are obtained. That is, it becomes possible to detect components with very good contrast (S/N).

Therefore, by sequentially checking the outputs of the comparator 22, it is possible to very accurately determine the presence or absence of components, positional deviation, and other mounting conditions, regardless of the brightness or darkness of the detected surface. Furthermore,
The output of the comparator 22 represents the comparison result of the two detection signals as "1", which is binarized with rOJ.
For example, there is also the advantage that shading (a phenomenon in which the periphery of an image becomes dark) that is often seen in images obtained by directly capturing images with a TV camera or the like is eliminated. Furthermore, since one line sensor 17 can detect both the component Q and the board R, it is possible to achieve highly accurate positioning using two line sensors, and to separate the reflected light into two line sensors. There is no need for a beam splitter or the like to provide the beam, and the optical system can therefore be configured very simply.

Next, a fifth optical mask 26 according to another embodiment of the present invention is applied.
As shown in the figure. In this optical mask 26, the width of the light transmitting part 26b for transmitting the reflected light from the substrate part R is narrower than the width of the other light transmitting part 26a.

Generally, on a printed board, the electrode part of the substrate part R (the electrode part P as shown in FIG. 7) is the brightest, and the light reflected therefrom has the strongest amount of light. However, the amount of light that can be detected by the line sensor is fixed within a certain range, and when a larger amount of light is detected, the detection signal becomes saturated. Therefore, in order to prevent the detection signal from being saturated by the strong reflected light from the electrode section, it is conceivable to reduce the sensitivity of the line sensor. The parts body Q,
) will not be detected. Therefore, instead of lowering the sensitivity of the line sensor, by using an optical mask 26 as shown in FIG. 5 to narrow down only the reflected light from the substrate part R, it is possible to detect even the dark parts of the component Q. Furthermore, even bright electrode portions of the substrate portion R can be detected without causing the saturation as described above.

Note that the width of the light transmitting portion 26b of the optical mask 26 may be appropriately set depending on the brightness of the substrate portion R.

〔Effect of the invention〕

According to the mounted component inspection device of the present invention, even if the reflectance of the surface to be detected is not uniform, L+ detection due to light wraparound etc. can be prevented and component detection with very good contrast (S/N) can be performed. In addition, the optical system for this purpose requires a very simple configuration and does not require complicated positioning.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a light irradiation means and a light detection means according to an embodiment of the present invention, FIG. 2 (al is an enlarged view showing the light receiving surface of the line sensor 17 shown in FIG. 1, (bl is an enlarged view showing the optical mask 16 shown in FIG. 1, FIG. 3 is a diagram showing an example of the reflected light intensity at each position on the printed board P, FIG. 4 is the same example) 5 is an enlarged view showing an optical mask according to another embodiment of the present invention, FIG. 6 is a configuration diagram showing an optical system of a conventional device, and FIG. 7 is a circuit diagram showing a signal processing circuit according to a conventional device. It is a diagram showing an example of detection signal strength for explaining conventional problems. 12... Semiconductor laser, 13... Collimating lens, 14... Cylindrical lens, 15... Imaging lens, 16... Optical mask, 16a, 16b... Light transmitting section, 16c, 16d... Light blocking section, 17... Line sensor, 1'7a... Light receiving element, 18... Drive circuit, 19...Sample circuit, 20.21...Amplifier, 22...Comparator, 26...Optical mask.

Claims (1)

[Claims] 1) Light irradiation means (12, 13, 1) for irradiating a slit-shaped light beam (l_1) onto a printed circuit board on which components are mounted.
4), and a line sensor (17) formed by arranging a plurality of light receiving elements (17a) having long rectangular light receiving surfaces in a line corresponding to the height direction of the component, and a line sensor (17) having a plurality of light receiving elements (17a) arranged in a line corresponding to each of the light receiving elements. From the substrate portion of the printed board by irradiation with the light beam, the light beam is irradiated through an optical mask (16) in which light transmitting portions (16a, 16b) and light blocking portions (16c, 16d) are arranged in a substantially checkered pattern. light detection means (15, 16, 17) that alternately detects the reflected light (l_3) of the component and the reflected light (l_2) from the top surface of the component for each of the light receiving elements; signal processing means (18, 19, 20, 21, 22) that alternately extracts and separates each element, compares the separated detection signals with each other, and determines the mounting state of the component based on the comparison result; A mounted component inspection device comprising: 2) The light irradiation means includes a semiconductor laser (12) that outputs a laser beam, a collimating lens (13) that converts the laser beam outputted by the semiconductor laser into parallel light, and a collimating lens (13) that converts the laser beam outputted by the semiconductor laser into parallel light. The mounted component inspection apparatus according to claim 1, further comprising a cylindrical lens (14) that converts light into the slit-shaped light beam. 3) The mounted component inspection apparatus according to claim 1 or 2, wherein the area of the light transmitting portion of the optical mask is adjusted based on the intensity of the reflected light. 4) The implementation according to any one of claims 1 to 3, wherein the optical mask is formed by forming an opaque film on a transparent glass plate as the light blocking portion. Parts inspection equipment. 5) The mounted component inspection apparatus according to claim 4, wherein the opaque film is a chromium vapor-deposited film. 6) The mounted component inspection apparatus according to any one of claims 1 to 5, wherein the line sensor is a CCD line sensor.