JP2682073B2 - Appearance inspection device for thick film printing patterns - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for inspecting the appearance of a thick film printed pattern, and in particular, for clearly observing a printed pattern having a polarization characteristic to judge its quality. Regarding the device.

(Prior Art) Thick film printed patterns such as conductive patterns, reference point patterns, resistance patterns, and insulation patterns printed on a substrate by a printing device have defects such as cuts and short-circuited parts before mounting electronic components on the substrate. A visual inspection is performed to see if there are no parts. Conventionally, such visual inspection has been performed by an operator visually observing with a microscope or the like.

(Problems to be solved by the invention) However, the visual inspection by the operator does not improve the work efficiency, and the inspection standard varies due to the individual error of the operator, etc., and the good product is determined to be defective product or the defective product is determined. There was a problem that it was easy to make a mistaken judgment such as judging that it was a good product.

As a countermeasure against this, it is conceivable to perform a visual inspection of the printed pattern with a camera. In this case, the pattern must be clearly observable with a clear contrast with the surroundings. However, for example, when observing a conductive pattern made of silver palladium or copper printed on a white ceramic substrate, this pattern is observed as a color close to white, so the contrast with the white ceramic substrate is extremely weak, and the observation is clear. Can not.

By the way, although silver palladium, copper, etc. have polarization characteristics, the ceramic substrate does not have polarization characteristics. Therefore, when observing a pattern containing them as a component through a polarizing plate, they show a white ceramic substrate. On the other hand, it is clearly observed as a black pattern having a strong contrast, and the appearance inspection can be performed accurately.

Therefore, the present invention has been made in consideration of the above points, and an object of the present invention is to provide means for accurately inspecting the appearance of the pattern while utilizing the polarization characteristics of the pattern.

(Means for Solving the Problems) A visual inspection apparatus for a thick film printed pattern according to the present invention includes a positioning portion for a substrate, a linear image camera and an area camera for observing the thick film printed pattern printed on the substrate from above. , A pair of left and right plate-shaped light sources that are long in the same direction as the long direction of the long linear image sensor built in this linear image camera on both sides of this linear image camera and the optical axis of the area camera A ring-shaped light source provided, and a first polarizing plate and a second polarizing plate which are respectively disposed on the optical paths of light emitted from these light sources and reflected on the substrate and incident on the linear image camera and the area camera. It is composed of a polarizing plate, a switching device for switching the polarization angle of the polarizing plate on the area camera side, and a zoom drive device for adjusting the magnification of the area camera.

(Operation) According to the above configuration, various printing patterns such as a printing pattern having a polarization characteristic printed on the substrate, a printing pattern having no polarization characteristic, and a large and small printing pattern can be enhanced by using the linear image camera and the area camera. It is possible to observe clearly by contrast and perform these appearance inspections collectively and with good workability.

Example Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of the appearance inspection device, FIG. 2 is a side view, and 1 is an X-direction moving device, which is a base plate 2, a feed screw 3 for moving the base plate 2 in the X direction, and a feed. It is composed of a nut 4, a feed screw driving motor 5, a guide portion 6, and the like.
The equipment described below is mounted on this base plate 2,
These devices are integrally moved in the X direction.

Reference numeral 10 denotes a linear image camera mounted on the front of the base plate 2 and has a linear image sensor 11 built therein.
The linear image camera 10 has characteristics that are advantageous for observation over a wide range. Reference numeral 12 denotes an area camera arranged on the side of the linear image camera 10, and an area type image sensor 13
Is built-in. The area camera has a characteristic advantageous for observing a narrow range. Reference numeral 7 denotes a zoom driving device for the area camera 12, which drives a zooming device for observing a pattern requiring high precision, such as a reference point pattern, to increase the magnification of the camera 12. 20 is both cameras 10,12
The thick film print pattern printed on the upper surface of the substrate positioned below the substrate is observed by the two cameras 10 and 12, as will be described in detail later. Reference numeral 21 denotes a Y-direction moving device, which is a Y-direction moving table 23 that moves on the base 22 in the Y direction.
The substrate 20 is positioned by the positioning portions 24, 24 of the substrate 20 formed of a clamp member provided on the table 23, and the substrate 20 is moved in the Y direction. 25 is a drive motor, 26 is a board positioning part 24, 24
The conveyor is carried in and out of the conveyor.

Reference numerals 14 and 15 denote light sources of the linear image camera 10. The light sources 14 and 15 are composed of plates 16 and 17 disposed so as to sandwich the camera 10 from both sides and a flexible cable 18 connected to the plates 16 and 17. ing. Optical fiber inside cable 18
The substrate 20 is accommodated therein and irradiates the substrate 20 with light from the lower surfaces of the plates 16 and 17. This pair of left and right plate-shaped light sources 14,1
The longitudinal direction of 5 is the same as the longitudinal direction of the long linear image sensor 11 built in the linear image camera 10. That is, the lower surfaces of the plates 16 and 17 are parallel to the linear image sensor 11, and the light is uniformly emitted along the length direction of the sensor 11 (see also FIGS. 3 and 4). See). In addition, the camera 10 and the light sources 14, 15
The first polarizing plate 8 and the second polarizing plate 9 are respectively disposed in the camera, and the camera 10 observes a conductive pattern having a polarization characteristic printed on the entire surface of the substrate 20. Reference numeral 30 denotes a light source device provided below the area camera 12, and details thereof will be described with reference to FIG.

The light source device 30 includes a ring-shaped light source 31, a first polarizer 3
2, a second polarizing plate 33, a ring 34 for mounting the polarizing plate 32, a ring gear 35 for adjusting the rotation angle of the polarizing plate 33, and the like.
36 is a flexible cable in which an optical fiber is stored. First
The polarizing plate 32 is disposed at a position corresponding to the center hole of the ring-shaped light source 31. The second polarizing plate 33 has a ring shape, and is mounted on a ring gear 35 with screws 36. The ring-shaped light source 31 is provided on the optical axis of the area camera 12,
The light emitted from the light source 31 passes through the second polarizing plate 33 and is transmitted to the substrate.
The light reflected by the light 20 is transmitted through the first polarizing plate 32 and is incident on the area camera 12.

In FIG. 2, reference numeral 37 denotes a polarization angle switching device, which comprises a pulse motor 38 and a gear 39 driven by the pulse motor 38 to rotate the gear 35. The pulse motor 38 drives the pulse motor 38. Thereby, the second polarizing plate 33 is rotated, and the rotation angle with respect to the first polarizing plate 32 is adjusted. When observing a printing pulse having a polarization characteristic, the polarizing plates 32 and 33 irradiate only the light oscillating in a certain direction, and the reflected light is made incident on the area camera 12 to make the printing pattern clear. To observe. FIG. 6 (a) shows a state in which the polarization directions of the polarizing plates 32 and 33 coincide with each other, and the pattern P is observed normally. Further, in FIG. 3B, the characteristic directions of the two polarizing plates 32 and 33 are orthogonal to each other, and therefore, a polarization is imparted, and a pattern having the polarization characteristic can be clearly observed. Further, FIG. 7 shows presence / absence of polarization characteristics of various patterns, non-polarization, and luminance observed by a camera in polarization. That is, the conductive pattern made of silver palladium (AgPd) and the reference point pattern have polarization characteristics, and are observed white when no polarization is applied, but black when polarization is applied. In addition, the resistance pattern made of ruthenium oxide (RuO ₂ ), the insulating pattern made of glass, and the ceramic substrate made of alumina do not have polarization characteristics, and therefore, they are observed with the same brightness in non-polarized light and polarized light. It should be noted that the materials shown in this table are merely examples. For example, a conductive pattern containing copper as a component or a reference point pattern also has polarization characteristics as in the case of silver palladium. Further, in the present embodiment, the polarizing plates 8 and 9 on the side of the linear image camera 10 are not equipped with a polarization angle switching device, but these polarizing plates 8 and 9 also have the same configuration as the area camera 12 side. A polarization angle switching device may be provided. Further, the polarization angle can be arbitrarily determined in addition to the option of giving or not giving the polarization angle, and the pattern may be observed by giving an intermediate polarization angle.

FIG. 8 is a flow chart showing the inspection sequence of the thick film print pattern printed on the substrate 20 by the appearance inspection apparatus, and the inspection sequence will be described with reference to this drawing.

In the figure, A is a printing step of a thick film printing pattern by a screen printing apparatus, B is an appearance inspection step by the above-mentioned appearance inspection apparatus, and C is a drying and firing step of a pattern by a drying and firing apparatus. First, the substrate 20 is carried into a screen printing apparatus, and a conductive pattern and a reference point pattern containing silver palladium having polarization characteristics are printed at the same time. An appearance inspection is performed to determine whether there is a defective portion such as a short circuit or a short circuit. The conductive pattern is printed on almost the entire surface of the substrate 20, so that the inspection is quickly performed by the linear image camera 10, which is advantageous for wide-area observation. Further, the reference point pattern is locally printed on a corner or the like of the substrate 20, and therefore, the inspection is performed by the area camera 12 which is advantageous for observation of a narrow range. Such observation is performed by driving the X-direction moving device 1 and the Y-direction moving device 21 and using the cameras 10 and 12.
And the light sources 14, 15, 30 are moved in the XY direction relative to the substrate 20. The conductive pattern containing silver palladium as a component and the reference point pattern have polarization characteristics. Therefore, by driving the switching device 37 to impart polarized light as shown in FIG. It is clearly observed with a strong black contrast to the white ceramic substrate 20 that does not have it. Of course, the linear image camera 10 is also always given polarized light by the polarizing plates 8 and 9. When observing the reference point pattern printed on the substrate 20 in a small size, the reference point can be observed with high accuracy by driving the zoom driving device 7 and increasing the magnification of the area camera 12. As described above, by providing the area camera 12 with the polarizing means and the zoom driving device 7, it is possible to observe the reference point requiring high accuracy with extremely high accuracy.

In this manner, the substrate 20 on which the appearance inspection of the conductive pattern and the reference point pattern has been completed is sent to the drying and baking apparatus and dried and fired, and the substrate 20 on which the drying and baking has been completed is returned to the screen printing apparatus again and insulated. The pattern is printed and then its appearance inspection is performed. The insulating pattern is generally printed locally on the conductive pattern, so that its appearance inspection is performed by the area camera 12, which is advantageous for precise inspection of a small area. Also, in this case, since the insulating pattern does not have polarization characteristics, it is observed as a gray intermediate luminance on a white conductive pattern when no polarization is applied, and is also observed as a gray intermediate luminance on a black conductive pattern when polarized light is not applied. You. As described above, the vitreous insulating pattern does not have polarization characteristics, and therefore, may be observed with or without polarization.

After the appearance inspection of the insulation pattern is completed, the insulation pattern is subsequently dried and baked, then the resistance pattern is printed, and the appearance inspection is also performed by the area camera 12. In this case, since the resistance pattern is black having no polarization characteristics, by observing the conductive pattern as white due to no polarization, the resistance pattern is observed as a clear black pattern on the white substrate 20 and the white conductive pattern. . After the appearance inspection of the resistance pattern is completed,
Is sent to a drying and firing apparatus, which is dried and fired and then carried out to the next step. The appearance inspection is performed between the printing step and the drying and firing step, but may be performed after the drying and firing step, or may be performed after both steps.

As described above, this appearance inspection apparatus is provided with the linear image camera 10 and the area camera 12 and also has the polarization means, so that both cameras 10 and 12 can be used properly or by appropriately providing polarized light. Therefore, inspection of various patterns can be advantageously performed.

(Effect of the Invention) According to the present invention, a linear image camera and an area camera are used to print various print patterns such as a print pattern having a polarization characteristic printed on a substrate, a print pattern having no polarization characteristic, and a large and small print pattern. Therefore, it is possible to perform clear visual observation with strong contrast and perform these visual inspections collectively and with good workability.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 1 is a perspective view of a visual inspection device, FIG. 2 is a side view of the same, FIG. 3 is a partial side view of a light source, and FIG. FIG. 5 is an exploded perspective view of the polarizing device, FIGS. 6A and 6B are plan views of the polarizing plate, FIG. 7 is a characteristic diagram, and FIG. 8 is a flowchart diagram. 1,21 …… XY direction moving device 8,32 …… First polarizing plate 9,33 …… Second polarizing plate 10,12 …… Camera 14,15,31 …… Light source 20 …… Substrate 24 …… Positioning unit 37 …… Switching device

Claims (1)

(57) [Claims] 1. A positioning portion of a substrate, a linear image camera and an area camera for observing a thick film printing pattern printed on the substrate from above, and a linear image camera provided on both sides of the linear image camera. A pair of left and right plate-shaped light sources elongated in the same direction as the longitudinal direction of the elongated linear image sensor, a ring-shaped light source provided on the optical axis of the area camera, and emitted from these light sources. A switching device for switching the polarization angles of the first polarizing plate and the second polarizing plate, which are reflected on the substrate and are respectively arranged in the optical paths of the light incident on the linear image camera and the area camera, and the polarizing angles on the area camera side. And a zoom drive device that adjusts the magnification of the area camera.