JPS59192902A - Position checking device for parts attached to substrate - Google Patents

Abstract

PURPOSE:To check the positions of parts automatically by projecting a laser beam from above a substrate and detecting reflected light from the mounted parts by an optical sensor. CONSTITUTION:The laser beam 7 from a laser light source 4 scans on the substrate 2 to be checked on a conveyance stage 10 in an X direction through a projection lens and an oscillating mirror 6. A Y-directional scan is made by moving the stage 10. The reflected light is made incident to a photodetecting element 9 through a condenser lens 8. The difference in height between a component 1 and a making 2-3 is utilized to discriminate between reflected light beams from the both, so the position and falling of the component 1 are checked automatically.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an inspection device for inspecting the position of board-mounted components for inspecting the presence or absence of abnormalities in the mounting state of components mounted on a board.

[Background of the invention]

The circuit boards used in home appliances are now shown in Figure 1 (a), and the mounting method is shown in Figures 1 and 2 (a) to 2.
(d) will be explained. In FIG. 2(a), the substrate 2
A conductor 2-1 is printed at the component connection position, and a white marking 2-3 is placed between the two printed conductors 2-1. As shown in Figure 2(b), reflow soldering 2
-2 is applied on the printed conductor 2-1".
) Now, this riff.

The connecting terminal 1-1 of the component 1 is placed on top of the raw solder 2-2, and in this state is welded in a high-temperature furnace, as shown in FIG. 2(j).

Although the use of chip components in this manner has advantages such as easy automation of attachment and miniaturization of the device, it is easy for inaccurate attachment positions to occur, and in some cases, components may even fall off.

A conventional method for inspecting misalignment and falling off of chip components will be explained with reference to FIG.

In FIG. 3, the laser beam 7 is directed toward the substrate 2 to be tested in the X direction.
Scan a width greater than the length of the test board in the X direction, and
The light-receiving element 9, which is being conveyed at a constant speed in the direction of The light 7-2 is discriminated and received based on the difference in the arrival point of the reflected light. The electric signal from the light receiving element 9 is compared with the position information of the chip component 1 known in advance, and if the reflected light 7-1 is received at the position where the component 1 should be,
This method assumes that the chip component 1 is normally mounted.

Chip resistors have different colors on their front and back sides; the front side is white, but the back side is black, so half of the top surfaces of the chip resistors on the automatically mounted board are black. For this reason, conventional methods have the drawback that the intensity of the reflected light from the chip resistor whose top surface is black is weak and the presence of reflected light is not recognized, reducing the detection rate.Also, chip resistors mounted automatically are also inspected. This is why an automatic position and dropout inspection device is desired.

[Purpose of the invention]

An object of the present invention is to provide an apparatus for automatically inspecting the position of components including the above-described automatically mounted chip resistor using an optical sensor.

[Summary of the invention]

The inspection device for dropping and misaligning parts attached to a board according to the present invention projects a laser beam above the board, and uses the reflected light to recognize the presence and position of multiple parts.
This will be explained with reference to FIGS. 4 and 5.

In FIG. 4, reference numeral 6 indicates an optical system in a position inspection device for board-mounted parts according to the present invention, in which a laser beam 7 emitted from a laser light source 4 is focused by a projection lens 5, and a vibrating mirror 6 is swept by the transport stage 1.
0 is scanned in the X direction. The scanning of the substrate 2 to be inspected in the Y direction is performed by moving the transport stage 10. The laser beam 7 projected onto the substrate 2 to be inspected is adjusted to an appropriate size by a projection lens 5 so that the required resolution can be changed. The light is focused on a spot and is reflected on the top surface of the chip component 1 or the marking 2-3 on the test board, but since the direction and intensity of the reflected light are different between the chip component 1 and the marking 2-3, this is to distinguish markings 2-6. In this case, since the diameter of the laser spot is small and the shape of the marking is similar to the shape of the component, the positional shift of the chip component 1 can also be identified. To identify the chip component 1, the information on the marking position stored in advance is compared with the reflected light from the marking 2-6, and if it is determined that the reflected light is from the marking 2-3, the chip component 1 has fallen off. 0 The characteristics of the reflected light and the light receiving method will be explained with reference to FIG. 5(a). 2
The reflected light 7-2 projected onto the light receiving lens 7-6 is condensed by the light-receiving lens 8 and enters the light-receiving element 9. However, the reflected light 7-1 (shown as a solid line) from the top surface 1-2 of the chip component is reflected by the light-receiving lens 8 and the light-receiving element using the difference in height between the test board 2 and the top surface 1-2 of the chip component. 9 is appropriately positioned so that the light does not reach the light receiving element 9. This allows the reflected light from the chip component 1 and the markings 2-3 to be reflected by the valve blade 1''. Marking position information stored as described above and marking 2
By comparing the detected information of the reflected light 7-2 of -6 with the detection information, the presence or absence of the Sitisop component 1 is identified. .

Here, regarding the projection direction of the laser beam 7, the signal S
To make /N good, consider the following self-considerations. That is, in FIG. 5(a), the direction of the laser beam 7 is tilted at a slight angle 8 from the vertical line i toward the side opposite to the light-receiving element 9. As a result, the side surface 1-6 of the component and the chip component 1
The laser beam is not projected onto the substrate portion 2-4 of the mounting portion, and no harmful or unnecessary reflected light is generated.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a position inspection device for board-mounted parts according to the present invention will be described with reference to the drawings.

In FIG. 4, optical system B has already been described. Here, the apparatus and movement of the test substrate 2 in the Y direction will be described.

As mentioned above, the stored position information is used to identify the markings 2-3, but the method of displaying this position information is by displaying coordinates with one corner of the test board 2 as the origin O. Therefore, the test board It is absolutely necessary to achieve a state of positioning with a high degree of accuracy. As a method for realizing this, the Ω transport stage 10 shown in FIG. 4 has been devised. That is, as shown in the figure, the rectangular transport stage 1002 has sides 10-1.
A step is provided so that the height of 10-2 is higher than the others, and the above-mentioned negative corner of the substrate 2 is pressed to the intersection point 0 of the step, thereby achieving highly accurate positioning. The method of crimping is to provide a presser spring 10-3 at a diagonal point of the origin 0 and push out the substrate 2 to be tested in the direction of the arrow at this point.

The transport stage 10 is moved in highly accurate steps by a separate moving mechanism, and this control is performed using a known technique.

Next, an explanation will be given of an embodiment regarding the light receiving element 9.

FIG. 5(b) shows a linear array sensor used as the light receiving element 9, in which the center line C is aligned with the scanning direction Use the equivalent. Test board 2 described above
The X coordinate of the coordinate and the light receiving element point 9- of the linear array sensor
1 and can be compared with the stored position information.

Taking the design values of a device that has been put into practical use as an example, the pitch of the light-receiving element points p-1 of the linear array sensor is 0.24 mm on the substrate 2, while the required accuracy of the mounting position of the chip component 1 is A sufficient resolution of about ±0.5+nm is obtained. Incidentally, regarding the movement pinch in the X direction, it is set to 0.24 mm as in the X direction, and for the detection of marking 2-3, as described below, ? :j7)X
, carried out at 16 points in three rears aligned with the pitch in the Y direction,
The presence or absence of parts is determined.

FIG. 6 shows the chip component 1 and mark on the test board 2.

Detection point p1 of reflected light by King 2-3 and optical system B
.about.p16, the coordinates of the center point p of marking 2-6 are (Xn, Yn), and these values are stored in advance for all deviations according to design values.

On the other hand, the detection points for determining the reflected light of marking 2-3 are 16
16 of pl"'? p16, which is located at a distance of d/2 considering the resolution d of the light receiving element and the pinch d in the Y direction.
Out of 16 detection points.

Marking 2-6 when there are multiple reflected lights 7-2
is determined to have been detected. In the embodiment, the number is in the range of 4 to 9. When the markings 2-6 are detected, it is determined that the chip component 1 is out of position or has fallen off.

FIG. 7 shows a schematic block diagram of an embodiment of the position inspection device for board-mounted parts according to the present invention. As described above, in the optical system 3, an electric signal for marking corresponding to the presence or absence of a chip component is output by scanning with the laser beam 7. In the signal processing section 11, the presence or absence of a marking is outputted according to the flowchart shown in FIG. detected and printer 1
3 is output. The chive device 12 is used to input design values (Xn, Yn) of the marquee position into the signal processing section 11 in advance.

In FIG. 8, first, the power is turned on to the device and the above data (XnXYn) is stored. Next, the substrate to be inspected is set on the transport stage 10, and inspection is started using the presser opening.

The above electrical signal processing is performed in one scan of the laser beam in the X direction, and the reflected light on one scan line is sent to the light receiving element 9.
are stored in raw points at corresponding positions. When one scan is completed in this way, the transfer stage 10 is moved in the Y direction by a signal from a separately provided end point sensor, and during the movement, an abnormality check of the chip component mounting position is performed in parallel. That is, the light-receiving element 9 has a self-scanning function, and the raw point information for the stored component position is extracted as a time-series signal.
A comparison is made with the stored information of Yn). If it is determined as a marking as a result of the comparison, the part number is temporarily stored and the next laser beam scan is started. Even if it is not determined as a marking, the next laser beam scan is started.

When the scanning of the entire surface of the board is completed in this way, the scanning of the laser beam is stopped, the part number of the abnormally mounted part temporarily stored is printed and alerted, and the inspection is completed.

In the above description, the circuit construction for comparing the marking position signal from the light receiving element 9 with the stored information can be easily realized using known techniques, and will therefore be omitted.

〔Effect of the invention〕

As described above, according to the position inspection device for board-mounted parts according to the present invention, it is possible to achieve the same results as originally described.

Abnormal mounting, such as misalignment or falling off of components, can be detected at high speed and with high accuracy on boards assembled using automatic mounting equipment and with components assembled at high density, regardless of whether the chip resistor is on the front or back. , ``The data is printed out, and inspection with a higher detection rate than conventional equipment can be performed. 3 shows the arrangement of the optical system of a conventional inspection device, and FIG. 4 shows the position inspection of a board-mounted component according to the present invention.

FIG. 5(a) is a block diagram showing a schematic configuration of an optical system that is an embodiment of the device. FIG. 5(a) shows the incident light of the laser beam in FIG. Element layout configuration diagram, Figure 5 (
b) shows the structure and arrangement of the light-receiving element using a linear array sensor; FIG.
FIG. 7 is a block diagram of an embodiment of the position inspection device for parts attached to a well plate according to the present invention, and FIG. 8 is a flowchart illustrating the inspection process in FIG. 7.

1...Chip parts, 2...Test board, 6. Optical system, 4... Laser light source, 5... Light projection lens, 6 ・Vibration mirror, 7...Laser beam, 8- Light receiving lens, 9. Light receiving element, 10 Conveyance stage, 11--signal processing unit, Figure 2 (C)　　　　　　　(〆) Sheep 4- Fertilizer Sheep y diagram (death) Child illustration Early 7 Figure

Claims (1)

[Scope of Claims] 1. Consists of a laser light source, a light projecting lens, and a vibrating mirror, and can project light from a small angle with respect to the vertical direction of the test board, and can project light onto the test board in the X direction. The laser spot can be scanned over a length range, and the light emitting part can receive the reflected light of the spot from the marking on the board, eliminating the reflected light from the top surface of the chip component mounted on the board. The optical system includes a light-receiving lens that does not receive light and a light-receiving section made of a light-receiving element using a near array sensor.
? 7. A position inspection device for a board-attached component, comprising a transport stage that can be positioned and mounted at a time, and that can be moved in the Y direction each time the scanning of the spot in the X direction is completed. 2. The transport stage is rectangular, and a part of a certain width along two sides of the rectangle has a step of an appropriate height compared to the other part, and the above-determined height of the test substrate is placed at the intersection of the steps. 1
The position inspection device for a board-mounted component according to claim 1, characterized in that it has a presser spring capable of crimping the corners.