JP5079678B2 - Device mounted appearance inspection apparatus and inspection method - Google Patents

Description

  The present invention relates to an appearance inspection apparatus for electronic component mounting, and more particularly to an apparatus and an inspection method for inspecting a soldering state of a printed circuit board printed with cream solder.

Conventionally, as a method of printing the cream solder (40) on the printed circuit board (4), the method shown in FIG. 15 has been performed. Cream solder (40) is a paste-like solder containing metal.
A printed circuit board (4) is disposed below the metal mask (9) having a plurality of holes (90) (90). A lump of paste-like cream solder (40) is placed on one end of the metal mask (9), and the solder (40) is inserted into the hole (90) with a squeegee (91) which is a pushing plate. The solder (40) in the hole (90) is imprinted and printed on the printed circuit board (4).
As is well known, when a copper pattern (41) is formed on the printed circuit board (4) and the solder (40) is printed accurately, the solder (40) is formed as shown in FIG. It is placed accurately without protruding from the pattern (41). However, if foreign matter or the like is present under the warp of the printed circuit board (4) or the metal mask (9), a gap is formed, and the solder (40) protrudes from the pattern (41) as shown in FIG. 16 (b). If the hole (90) of the metal mask (9) is clogged, the solder (40) may be placed on the pattern (41) only slightly as shown in FIG. 16 (c). In this case, since the soldering is not performed accurately, there is a possibility that the electronic component is not accurately soldered to the printed circuit board (4). In particular, as shown in FIG. 16 (b), when the solder (40) protrudes from the pattern (41), it contacts the adjacent solder (40), resulting in a so-called bridging failure.
Therefore, conventionally, an apparatus for inspecting the soldering state on the printed circuit board (4) has been proposed.

  FIG. 17 is a block diagram showing a conventional inspection apparatus (7) (see Patent Document 1). In this case, the printed circuit board (4) on which the solder (40) is printed on a plurality of patterns is imaged by the camera (70), and the image is sent to the image storage means (71). Next, the binarization means (72) binarizes the image stored in the image storage means (71), and the inspection window frame Q between the plurality of solders (40) (40) (FIG. 18 (a)). (See) is taken out and binarized. Thereafter, the projection means 73 obtains the projection of the binarized image. If the value of the projection image shown in FIG. 18B is equal to or greater than the threshold value S, the bridge in which the solder 40 and 40 are connected. It was bad. These processes and determinations are performed by the control unit (74).

As another conventional example, there is an apparatus for inspecting a soldering state on a printed circuit board (4) using a commercially available image scanner (see Patent Document 2). FIG. 19 is a cross-sectional view of the image scanner (2). As is well known, the image scanner (2) has a transparent upper surface cover (24) and a reading module (5) that can move left and right along the guide shaft (21). The jig (28) is placed on the cover (24), and the printed board (4) with the solder (40) facing downward is placed on the jig (28). The reading module (5) scans the image of the solder (40) along the guide shaft (21).
FIG. 20 is a cross-sectional view showing the inside of the reading module (5). The light from the light (53) illuminates the lower surface of the inspection object (not shown), and the reflected light enters the reading module (5) from the image reading unit (54) which is an opening. The light is reflected by the mirrors (55) (55a) (55b) (55c), passes through the lenses (56) (56a), reaches the CCD image sensor (57), and reads the image of the inspection object.
One end of the reading module (5) moves along one guide shaft (21), and the other end is placed on a guide (not shown).
As another conventional example, there is an example in which an image is captured by an image scanner, and a binarized image and a mask image are determined by a mask processing unit to determine a solder area and a solder misalignment. There is an inspection apparatus that performs a bridge determination by calculating predetermined coordinates and area by using a mask processing means obtained by inverting the binarized image and the mask image (see Patent Document 3).

JP-A-6-18237 Japanese Utility Model Publication No. 5-25871 Japanese Patent Laid-Open No. 2005-156381

The above inspection apparatus has the following problems to be solved. First, in the inspection apparatus (7) shown in FIG. 17, the camera (70) takes an image from a place where the solder (40) is high. Therefore, the distance between the camera (70) and the solder (40) is actually 30-80 cm apart. However, when trying to capture images of all the solder (40) (40) to be inspected from a high place, the resolution is too low to perform a precise inspection. Therefore, a general inspection method is such that the camera (70) or the inspection apparatus is moved back and forth and right and left to reduce the number of solders (40) and (40) to be inspected at one time. This complicates the structure of the inspection apparatus and makes the entire apparatus expensive.
Further, in the inspection apparatus shown in FIG. 19, since the printed circuit board (4) is placed on the jig (28), it requires manual labor. Therefore, although it is suitable for the inspection process or sampling inspection through manual labor, it is not suitable for continuously inspecting a plurality of solders (40) and (40) by automatically transporting the printed circuit board (4). . This is because the printed circuit board (4) needs to be placed with the solder (40) facing down in the inspection apparatus shown in FIG. However, in a state where the solder (40) is printed, the solder (40) is not cured, and if the solder (40) is turned downward, the solder (40) may be dripped or dropped. There is also a possibility that dust on the printed circuit board (4) may fall on the image scanner (2) or the transparent cover (24). This becomes a hindrance factor in image processing and a problem remains. In order to prevent the solder (40) or dust from falling, a special jig is required, which leads to an increase in equipment cost.
Further, in the image processing, since Patent Document 1 sets the inspection range individually, it takes too much time. In Patent Document 3, the quality of the solder is judged based on the area of the solder. However, the surface of the solder has irregularities that change every time it is printed, the color changes greatly, and a dark part also occurs.
In particular, it is difficult to determine whether the dark portion is solder or an adjacent resist, and since it changes as described above, it cannot be specified as the color of the solder. Therefore, it is difficult to accurately integrate the solder area, and there is a risk of erroneous determination due to insufficient solder and erroneous determination of the bridge.
The applicant turns the commercially available image scanner (2) upside down, conveys the printed circuit board (4) to the lower side of the image scanner (2), and continues the printed circuit board (4) with the solder (40) facing upward. Inspired by an inspection device.
An object of the present invention is to provide an apparatus capable of smoothly inspecting a soldering state at low cost using an image scanner (2).

The inspection apparatus moves along at least one guide shaft (21) and scans the image with the image reading unit (54) facing downward, and the reading module (5) is in a horizontal state. An image scanner (2) having a horizontal support member supported by the image scanner, a conveying means for conveying an inspection object to the lower side of the image reading unit (54) of the image scanner (2), and a reading module (5) scanning Means for processing the processed image and displaying it on the monitor (11) is provided.
A transparent cover (24) is provided on the lower surface of the image scanner (2) so as to face the inspection object, and the focal length between the image reading unit (54) and the inspection object is adjusted to the image scanner (2). For this purpose, a first means for finely adjusting the vertical interval and the inclination and a second means for finely adjusting the plane position and the angle θ for reading the inspection image are provided.
Further, the inspection apparatus superimposes the means for recognizing the pattern of the substrate before solder printing, the means for recognizing the pattern of the substrate after solder printing, and the pattern of the substrate before solder printing and the image of the pattern after solder printing. Is a means for collectively deleting the unprinted patterns that are not printed, and integrating the area of the entire pattern after solder printing that has not been deleted as a master, and is a pass / fail judgment criterion for the pattern to be inspected based on the master With means to set the area ratio,
After setting the area ratio to be a determination criterion, the remaining area of the pattern after solder printing, which is the inspection target conveyed to the lower side of the image scanner (2), is obtained, and the ratio of the remaining area of the pattern to the master is Whether or not the solder is insufficient is determined based on whether or not the area ratio is equal to or greater than the determination reference area ratio.
Further, the inspection apparatus superimposes the noise-processed pattern image and the master image on the pattern image after the solder printing, and adjacent inspection target patterns are connected or approached by the solder (40). A means for determining whether or not the solder (40) is connected or approaching each other is provided, and a bridge or a bridge device is determined.

1. Since the reading module (5) is supported by one guide shaft (21) and a horizontal support member, the image can be scanned even when the image reading unit (54) is directed downward. Furthermore, since the distance between the transparent cover (24) and the inspection object is secured, the image can be scanned smoothly.
Since the image is scanned from above the inspection object, dust or the like does not fall on the image reading unit (54) or the transparent cover (24) from the inspection object, and the inspection image can be scanned accurately. .
Since the image scanner (2) is focused by finely adjusting the vertical interval and inclination, it can be inspected with high accuracy.
2. Since the image scanner (2) uses a commercially available product or a partially modified version of the commercially available product, the soldered state printed on the upper surface can be automatically and continuously inspected without human intervention at low cost. .
3. Further, in the image processing, the inspection apparatus can specify the inspection range at a time, and the program creation time can be shortened. In addition, since the remaining area of the pattern on which the solder is not printed is integrated and the ratio of the remaining area with respect to the master is determined as to whether or not the area ratio is a criterion, it is easy to determine whether the solder is insufficient. is there. This determination is performed regardless of the area of the solder (40), so that it is simply determined whether adjacent patterns or printed solders are connected by solder, or whether the solder is approaching. There are few errors. Less mistaken judgments result in fewer production stops and better production efficiency. Even when a defect is judged, it is enlarged and displayed on the monitor, so that the defective part of the substrate can be easily understood. Therefore, pass / fail judgment is reliable and feedback can be performed in real time.

First Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. First, the configuration of the inspection apparatus will be described in detail.
FIG. 1 is a front view schematically showing the inspection apparatus (1), and FIG. 2 is a perspective view of the inspection apparatus (1).
The inspection device (1) is arranged on a conveyor belt (32) that extends from side to side and is intermittently driven, and a plurality of printed boards (4) and (4) to be soldered are mounted on the conveyor belt (32). They are placed apart from each other. A printing machine (8) is provided upstream of the conveyor belt (32) from the inspection device (1). On the downstream side of the conveyor belt (32) from the inspection device (1), there is an electronic component mounting machine on the printed circuit board (4) and a reflow furnace (not shown) for thermosetting the solder. The conveyor belt (32) of the printing machine (8) and the conveyor belt (32) of the inspection device (1) are slightly separated.
In the printer (8), the printed circuit board (4) is brought into close contact with the metal mask (9), and the cream solder (40) is printed on the pattern of the printed circuit board (4) by the squeegee (91). This process is the same as the conventional process.

The inspection device (1) is an image scanner (2) located above a printed circuit board (4) on which solder printing has been carried by a conveyor belt (32), and a personal computer that digitally processes the image of the image scanner (2) (10) “Hereafter referred to as PC (10)”, a monitor (11) that displays an image processed by the PC (10), and an operator can check the image on the monitor (11) to determine whether soldering is good or bad. It has a keyboard (12) for inputting. The digital image processing of the PC (10) will be described later. The image scanner (2) is a commercially available product or a part of the commercially available product, and can be obtained at low cost.
On the conveyor belt (32), a stopper (33) that comes into contact with the downstream end face of the printed circuit board (4) is provided so as to be able to protrude and retract, and when the printed circuit board (4) is scanned by the image scanner (2). Is restricted by the stopper (33). After the image operation, the stopper (33) is separated from the printed circuit board (4) and allowed to move downstream.

As shown in FIG. 2, a nut (35) is provided on the side of the image scanner (2), and the nut (35) is attached to a first screw shaft (30) erected on the conveyor frame (3). Screw together. If the first screw shaft (30) is rotated, the image scanner (2) can be moved up and down to adjust the distance from the printed circuit board (4) for image scanning. That is, the nut (35) and the first screw shaft (30) constitute adjusting means for adjusting the distance between the image scanner (2) and the printed circuit board (4) in millimeters.
By adjusting the distance between the image scanner (2) and the printed circuit board (4), not only the soldered state (40) of the printed circuit board (4) but also the electronic components are placed on the printed circuit board (4) and soldered. The attached state can also be inspected.

FIG. 3 is a bottom view of the image scanner (2), and FIG. 4 is a cross-sectional view of FIG. 2 cut along a plane including the line AA. The image scanner (2) has a reading module (5) that can move left and right along two guide shafts (21) and (21) that are spaced apart from each other. The reading module (5) is driven by the connected drive belt (23). The reading module (5) is horizontally supported by two guide shafts (21) and (21), and is fitted in one of the guide shafts (21) with a small margin, and the other guide shaft (21). It fits in a state where there is room. A transparent cover (24) covers the lower surface of the image scanner (2). Alternatively, the transparent cover (24) may be omitted, and a dust-preventing transparent cover (not shown) may be disposed in the reading unit.
In this example, unlike the normal use of the image scanner (2), the image reading unit (54) is directed downward. The scanning operation of the reading module (5) is controlled by the control circuit (29). Since the reading module (5) is fitted to the two guide shafts (21) and (21), the image scanner (2) is moved up and down. It can be used even if it is reversed.
Two conveyor belts (32) and (32) are provided apart from each other in accordance with the width of the printed circuit board (4). Each conveyor belt (32) is received by a belt receiver (34), and each belt receiver (34) is screwed onto a second screw shaft (31) provided between the frames (3) and (3). By rotating the second screw shaft (31), the interval between the conveyor belts (32) and (32) can be adjusted.

(Inspection procedure)
Hereinafter, the inspection procedure will be described. The printed circuit board (4) on which the cream solder (40) is printed by the printing machine (8) is placed on the belt (32), stopped by the stopper (33), and below the image scanner (2). To position. The vertical distance between the image reading unit (54) and the transparent cover (24) of the image scanner (2) and the printed circuit board (4) is adjusted in advance by rotating the first screw shaft (30). Is about several millimeters. It is not limited to this dimension.
The reason why a gap of several millimeters is provided between the image reading unit (54) or the transparent cover (24) and the printed circuit board (4) is as follows (i) to (iv).
(i) Since the cream solder (40) is not yet cured, when the image reading unit (54) or the transparent cover (24) is in contact with the printed circuit board (4), the cream solder (40) is transferred to the image reading unit (54). Or there exists a possibility of adhering to a transparent cover (24).
(ii) If there is no gap, the printed circuit board (4) cannot be correctly conveyed by the belt (32).
(iii) In the image scanner (2), an image cannot be scanned accurately unless there is a gap of several millimeters between the printed circuit board (4) as an inspection object.
(iv) If the focal length of the image reading unit (54) is about 8 mm and there is no gap, the image cannot be scanned accurately.
When the reading module (5) of the image scanner (2) is moved to the left and right, the image of the solder (40) of the printed circuit board (4) is captured, and the image is processed by the PC (10). Display on the monitor (11). The operator looks at the image on the monitor (11) to judge whether the solder printing is true or not, and if it is judged as “good”, the belt (32) is moved to move the next printed circuit board (4) to the image scanner ( Move to the bottom of 2). If “No”, that is, a defective product is determined, the printed circuit board (4) is taken out. In this case, the stopper (33) is not released and the image on the monitor (11) is not updated until the printed circuit board (4) is taken out.

  Data that has been subjected to image processing by the PC (10) and judged pass / fail, the customer name of the printed circuit board (4), the name of the object to be inspected, the date, the inspection method, etc. are all stored in the PC (10) as information. This information is preferably used for reproduction. Further, in the display on the monitor (11), the portion to be determined may be automatically enlarged and displayed to facilitate the determination. Further, in order to feed back the determination of “NO” to the previous process, the “NO” position on the printed circuit board (4) may be displayed in a reduced size so that the position can be easily confirmed. These settings can be handled by software in the PC (10).

The configuration for horizontally supporting the reading module (5) is not limited to the two guide shafts (21) and (21). For example, as shown in FIG. 5, one guide shaft (21) supports one end of the reading module (5), and the protruding piece (58) protrudes from the other end of the reading module (5). . The receiving piece (25) may protrude from the inside of the cabinet (20) of the image scanner (2), and the receiving piece (25) may receive the lower surface of the protruding piece (58). Further, as shown in FIG. 6, two projecting pieces (58) and (58a) may be provided apart from each other in the vertical direction, and the lower surface of the upper projecting piece (58) may be brought into contact with the upper surface of the piece (25). Good. In this case, there may be a gap between the lower projecting piece (58a) and the lower surface of the receiving piece (25). In other words, the interval between the projecting pieces (58) and (58a) is not required to have an accurate accuracy, which can suppress an increase in cost. As shown in FIG. 7, the upper projecting piece (58) may be received by the guide shaft (21).
Further, as shown in FIG. 8, a receiving member (26) is provided on the transparent cover (24), and the protruding member (58) protruding from the other end of the reading module (5) by the receiving member (26). The lower surface may be received. 5 to 8, the drive belt (23) is not shown.

Further, as described above, it is necessary to leave a gap of several millimeters between the transparent cover (24) and the printed circuit board (4). In the above, the adjusting means composed of the nut (35) and the first screw shaft (30) provided a gap between the transparent cover (24) and the printed circuit board (4). The configuration shown in FIG. 9 may be used.
FIG. 9 is a side sectional view of an image scanner (2) showing another embodiment, and a spacer (6) is provided between the frame (3) of the conveyor and the transparent cover (24) of the image scanner (2). Provided. Thus, a gap may be provided between the transparent cover (24) and the printed circuit board (4). The spacer (6) may pass through the frame (3) and be placed on the floor surface (69), as indicated by a dashed line in FIG.
FIG. 10 is a front sectional view of an image scanner (2) showing another embodiment. As in FIG. 9, a spacer (6) is provided between the conveyor frame (3) and the transparent cover (24) of the image scanner (2). However, unlike FIG. 9, the lower end of the image scanner (2) is pivotally supported (60) by the left spacer (6) in FIG. With the configuration shown in FIG. 10, after the inspection is completed, the image scanner (2) can be rotated upward about the pivot (60) to take out the inspected printed circuit board (4) from above. However, it is not limited to this. Thereby, a downstream conveyor and a stopper (33) become unnecessary, and can reduce installation cost.
Alternatively, it is also preferable to attach slide guides (not shown) on both sides of the image scanner (2) and slide the image scanner (2) to the back side after inspection to take out the printed circuit board (4).

Second Embodiment FIG. 11 is a plan view showing an image scanner (2) in another embodiment. A typical commercially available scanner has a maximum reading of A4 size (length 21 cm × width 30 cm), and the size of the printed circuit board 4 is increased when the resolution is increased with the A4 size. In this example, three reading modules, that is, a first reading module (5), a second reading module (50), and a third reading module (51) are provided in the image scanner (2). For convenience of illustration, the guide shafts (21) and (21) are not shown. The area 1/3 from the upstream side of the printed circuit board (4), that is, the right side is scanned with the first reading module (5), and the area of 1/3 from the downstream side of the printed circuit board (4), that is, the left side. The image is scanned by the second reading module (50). That is, in FIG. 12, the image of the area X is scanned by the first reading module (5), and the area Y is scanned by the second reading module (50). That is, in the first and second reading modules (5) and (50), image scanning is not performed on the region Z at the center in the longitudinal direction of the printed circuit board (4). At this time, the printed circuit board (4) located on the downstream side of the printed circuit board (4) is subjected to image scanning on the remaining 1/3 of the region Z by the third reading module (51). By this method, contact between the first and second modules (5), (50) is avoided.
Next, the stopper (33) is released from the printed board (4), and the printed board (4) is sent to the third reading module (51). In the third reading module (51), the region Z is image-scanned. In this example, since the image of the solder (40) is scanned by the three reading modules (5), (50) and (51), the scanning time can be shortened. That is, since the inspection target surface is divided and the inspection target surfaces divided by the reading modules (5), (50), and (51) are read, the time for image scanning can be shortened.

FIG. 13A is a plan view showing the positional relationship of the first to third reading modules (5), (50), and (51) that scan the printed circuit board (4) of another size. The size of the printed circuit board (4) is about 2/3 of the longitudinal direction. In this case, there is no image between the right end of the printed circuit board (4) indicated by V in FIG. 13 and the first reading module (5). Is not scanned. However, the second reading module (50) scans the left edge of the printed circuit board (4), and the third reading module (51) scans the image of the longitudinal center of the printed circuit board (4). The same as above.
The vertical and horizontal sizes of the printed circuit board (4) are not limited to the A4 size described above, and may be a size that is longer than the A4 size. For example, when the width is longer than A4, the above FIG. 11 can be applied. If the length is long, as shown in FIG. 13 (b), a plurality of reading modules (5) and (5) for scanning at right angles to the conveyor belt (32) may be arranged.

Third Embodiment FIG. 14 is a plan view showing an image scanner (2) in another embodiment. In this example, a plurality of vertical reading modules (52) and (52) in FIG. 14 are provided, and the vertical reading modules (52) and (52) do not move. Instead, the printed circuit board (4) on the conveyor belt (32) moves. This is because it takes a considerable time to inspect the printed circuit board (4) with a high resolution of about 5 to 10 microns in the inspection of scratches, dirt, dust and patterns. Therefore, compared with the horizontal type, the flat area is small, and a lot of vertical type reading modules (52) and (52) are provided, the inspection surface is divided, the moving distance of the printed circuit board (4) is short, and the scanning time is reduced. . The number of vertical reading modules (52) and (52) is not limited to the number shown in FIG.

Fourth Embodiment FIG. 26 (a) is a side sectional view of an image scanner of another embodiment, and FIG. 26 (b) is a plan view thereof. A protective cover (200) is attached to the outside of the image scanner (2), and the lower surface of the protective cover (200) is covered with a transparent cover (24). A stay (300) covers the outside of the image scanner (2), and the lower end of the stay (300) is attached to the conveyor frames (3) and (3) with screws (310). The top surface of the stay (300) and the upper surface of the protective cover (200) are connected by two first adjustment screws (210) and (210) separated along the width direction of the image scanner (2). The vertical distance and inclination θ1 between the reading module (5) in (2) and the printed circuit board (4) as the inspection object are adjusted by rotating the first adjusting screws (210) and (210). In other words, the first adjustment screws 210 and 210 make a first adjustment to finely adjust the vertical interval and the inclination θ1 in order to adjust the focal length between the image reading unit 54 of the reading module 5 and the inspection object. The means is configured.
However, the first adjusting screw (210) is screwed onto the top surface of the stay (300) with a margin to allow slight backlash in the planar direction. A second adjustment screw (220) (220) is screwed onto the side surface of the stay (300) and the side surface of the protective cover (200), and by rotating the second adjustment screw (220) (220), The planar position and angle θ2 of the reading module (5) are adjusted. That is, the second adjustment screws 220 and 220 constitute a second means for adjusting the planar position and the angle θ2 of the image reading unit 54 of the reading module 5.

The reading module (5) can scan substantially parallel along the direction of movement of the conveyor belt (32). If the length of the printed circuit board (4) is A4 size (length 21 cm x width 30 cm) or less, the image is read in one scan, but if it exceeds the A4 size, it is scanned in two steps. On the frame (3), a first stopper (320) and a second stopper (330) are provided along the conveying direction of the conveyor belt (32). The first stopper (320) and the second stopper (330) can be moved up and down toward the printed circuit board (4). When the printed circuit board (4) does not face the reading module (5), the first stopper (320) and the second stopper (330) move up. Yes.
When the length of the printed circuit board (4) exceeds the A4 size, the first stopper (320) is first applied to the side surface of the printed circuit board (4) as shown in FIG. The front half A1 along the transport direction is scanned. Thereafter, the contact between the first stopper (320) and the printed circuit board (4) is released, and as shown in FIG. 26 (d), the printed circuit board (4) is positioned on the conveyance side of the printed circuit board (4). (330). Thereafter, the remaining rear portion B1 region is scanned.
In general, the reading module (5) of the commercially available image scanner (2) can scan only up to A4 size. However, in this example, even if the horizontal length of the printed circuit board (4) exceeds the A4 size, it can be read up to about 60 cm by scanning in two steps.

Fifth Embodiment FIG. 27 (a) is a side sectional view of an image scanner of another embodiment, (b) is a plan view thereof, and (c) and (d) are scanning operations of the reading module (5). FIG. In this example, the scanning direction of the reading module (5) is substantially orthogonal to the conveyance direction of the printed circuit board (4). The configuration in which the first adjustment screws (210) and (210) and the second adjustment screws (220) and (220) are provided is the same as the embodiment shown in FIG.
In this example, the reading module (5) can scan substantially perpendicular to the direction of movement of the conveyor belt (32). A protective cover (200) is put on the stay (300), and the image scanner (2) is suspended from the stay (300). Only one printed circuit board (4) having a length of about 21 cm can be read by one scan of the reading module (5). However, the printed circuit board (4) is conveyed and read again, that is, by scanning twice, the printed circuit board (4) having a length of about 30 cm and a width of about 40 cm can be read.

(First example of inspection image processing)
An example of digital image processing and determination means of the PC (10) after reading by the image scanner (2) will be described in detail. Other examples will be described later.
FIG. 21 is a schematic plan view of a board before solder printing showing a pattern (41) to be solder-printed and a pattern (41a) not to be solder-printed on the printed board (4). A and B are semiconductors, and C is a chip, which is an electronic component to be mounted later. D is a solder adhesion preventing resist coating film. The resist is generally green and is thinly coated on the entire surface except for the patterns (41) and (41a). Moreover, the pattern (41a) not subjected to solder printing is a pattern in which solder is manually attached in a later process, for example.
FIG. 22 shows a state in which the solder (40) is printed on the pattern (41) to be solder-printed on the printed circuit board (4) of FIG. In FIG. 22, the solder (40) covers the pattern (41), and the pattern (41) is hidden. On the other hand, the state where only the pattern (41a) not printed by solder exists is shown.

In the PC (10), the pattern (41) (41a) of the board before solder printing shown in FIG. 21 is extracted, and then the binarized and noise processed pattern image is recognized. Next, the solder color of the substrate after the solder printing shown in FIG. 22 is extracted, and the pattern image after the solder (40) printing subjected to binarization and noise processing is recognized. However, in this case, it is executed after enlarging and confirming on the monitor (11) whether or not the printing is correctly performed. Of course, if there is a problem, start over. In the case of accurate printing, the image is conveyed downstream after the image recognition. Next, the pattern (41) (41a) image of FIG. 21 and the pattern image after printing the solder (40) are overlapped, and the pattern (41a) that is not to be inspected without the solder (40) printed is collectively deleted. To do.
Thereby, only the pattern (41) on which the solder is to be printed exists. The total areas of the respective patterns (41) are integrated and used as a master. Next, based on the master, an area ratio serving as a reference for determining whether the pattern (41) to be inspected is acceptable or not is set. The area ratio refers to an allowable range of the area of the pattern (41) that remains without being printed with respect to the entire area of the pattern (41). The integrated area and area ratio are stored in the PC (10), and after setting the area ratio, the area of the pattern (41) to be inspected that has been conveyed to the lower side of the image scanner (2) is obtained.

23 (a), (b), (c), and (d) show a state in which the solder (40) is printed on a part of the pattern (41) on the inspection board after the solder printing. The area of the remaining pattern (41) is divided by the master to obtain the ratio of remaining pattern (41). If the pattern (41) remains beyond the area ratio that is a criterion for pass / fail judgment, it is judged that the solder is insufficient.
That is, the shortage of solder is determined based on whether or not the remaining area of the pattern (41) after solder printing is equal to or larger than the area ratio that is a criterion.
For example, as shown in FIG. 23A, when the solder (40) is not printed on the entire surface of the pattern (41), the pattern (41) remains. When the reference area, which is a pass / fail criterion for the pattern (41), is set to 20% or less, the solder (40) is printed on the pattern (41) in FIG. Since the remaining area of the pattern (41) is 20% or more of the entire area of the pattern (41), it is recognized that the solder is insufficient.
In FIG. 23 (b), the solder (40) is accurately printed on the entire surface of the pattern (41), and the remaining area of the pattern (41) is 0%, which is 20% or less.
Even if there is a shadow due to the unevenness of the solder (40), the pattern (41) under the shadow is hidden and cannot be seen, so there is no effect on the determination of insufficient solder. That is, as shown in FIG. 23 (c), even if there is an area (40D) where the boundary between the resist and the solder (40) is ambiguous, the pattern (41) below is hidden and the pattern (41) is If the exposed part is 20% or more, it can be determined that the solder is insufficient. On the contrary, in FIG. 23 (d), the pattern (41) is hidden behind the ambiguous area (40D) and cannot be seen at all.

In general, the image processing extracts the color of the inspection object and specifies the color distribution and brightness of the inspection object in red, green, and blue (RGB) corresponding to the three primary colors of light. Thereafter, it is recognized by performing binarization processing and noise processing that are generally performed. However, there is a possibility that the color of the solder (40) changes every time printing is performed, and light is irregularly reflected so that RGB is reflected in the mottle, making it difficult to specify the color of the solder (40). In this example, the area of the pattern (41) having no color change is calculated. By this means, misjudgment of lack of solder can be reduced.
The surface of the printed solder (40) has large irregularities and a large color change compared to the copper pattern (41) due to the size of solder particles and uneven printing. When extracting the color of the solder, there is a possibility that the boundary line between the resist and the solder (40) may become inaccurate due to partial mixing with the color of the resist. This tendency is particularly seen in image reading by the image scanner (2). Therefore, there is a possibility that the determination of the solder area is not accurately performed. In view of this, the present invention has decided to integrate the area of the pattern (41) with relatively little unevenness. By this means, misjudgment of lack of solder can be reduced.

FIG. 24 (a) shows a pattern image after printing the solder (40) subjected to noise processing after binarization processing and an image of a pattern (41) as a master, and adjacent patterns (41) (41) are overlapped. Shows a bridge state where the two are connected by solder (40). The connected state is recognized, and it is determined whether or not it is in a bridge state. In this example, as shown in FIG. 24B, even if there is an area (40D) where the boundary line between the resist and the solder (40) is inaccurate and ambiguous, as shown in FIG. (41) Simply determine whether or not the solder (40) is connected or approached by the solder (40) or whether the solder (40) is connected or approached by the solder (40). be able to. Accordingly, it is possible to reduce the erroneous determination of the bridge.
As described later, the master may be formed by superimposing a pattern on the substrate before solder printing and an image (95) of the film (96).

FIG. 24 (c) shows the bleeding state of the solder (40). The blur solder (40) is attracted to the center of the pattern by the surface tension of the solder when the solder is melted, and the blur is often reduced or eliminated as shown in FIG. This phenomenon tends to attract the solder because the resist coating film is present between adjacent patterns. However, when the adjacent patterns (41) and (41) are connected by the solder (40), the solder (40) of both the patterns (41) and (41) is pulled together and soldered while the bridge exists.
Conventionally, even if the bleeding solder (40) protrudes from a predetermined coordinate range, the soldering (40) may not be connected, and there is a risk of erroneous determination as a bridge. In this example, it is only recognized whether adjacent patterns (41) and (41) are connected or approached by the solder (40), and there is no possibility of erroneous determination.

Further, as shown in FIGS. 25 (a) and 25 (b), even in the case of solder printing misalignment, if the remaining area of the pattern (41) is within the range of the area ratio that is a criterion, The outside is determined to be defective. Even if it is within the above range, if it is connected by the solder (40), there is no worry because it is determined as a bridge.
Further, if the distance between the adjacent solders (40) and (40) is equal to or less than a certain length, it is determined that the product is defective because there is a possibility of bridging. In other words, when components are mounted on the creamy solder (40) (40), the solder (40) (40) may protrude from the patterns (41) (41). If adjacent patterns (41) and (41) or solders (40) and (40) are very close, solder (40) and (40) may be connected. Therefore, if adjacent patterns (41), (41) or solders (40), (40) are extremely close to each other, it is determined that there is a possibility of bridging (referred to as a bridging mechanism) and a defective product is determined.

When all the inspection of the inspection substrate is completed and it is determined that it is a non-defective product, the substrate is transported downstream. Specifically, the stopper (33) is released, and the conveyor belt (32) is driven to convey the command signal from the PC (10) to the control device.
If there is a defect, the conveyance command signal is not sent and the stopper (33) is not released. On the monitor (11), the defective portion is enlarged and displayed with a red frame, and the entire reduced substrate and the position of the defective portion are displayed on the corner of the monitor (11). The operator judges the quality by looking at the image. If it is determined that the product is non-defective, the OK button on the keyboard 12 is operated to transport the substrate downstream. If it is determined to be defective, the substrate is taken out. Since the defective part is known, feedback is provided. That is, the printer (8) is corrected or the metal mask (9) is cleaned to remove the cause of the defect.

(Second example of inspection image processing)
As described with reference to FIG. 15, when the cream solder (40) is printed on the printed circuit board (4), it is necessary to prepare a metal mask (9) having a plurality of holes (90) (90). is there. The position and size data of the holes (90) and (90) of the metal mask (9) can be taken into the PC (10) as photo data. The photo data does not include data of a pattern (41a) which is not solder-printed. In this example, this photo data is used to collectively delete the pattern (41a) that is not covered by the solder (40) and is not inspected. That is, in the first example of the inspection image processing, the pattern image (41) of the board after solder printing is superimposed on the pattern (41) (41a) of the board before solder printing, and the pattern (41a) not to be inspected is deleted. However, in this example, instead of the pattern image (41) of the board after solder printing, photo data is placed on the patterns (41) and (41a) of the board before solder printing.

As shown in FIG. 28 (a), an image (95) of the hole (90) is generated based on the photo data, and the image is printed on the upper surface of the transparent film (96). Reference marks (99) are provided on the film (96), and similar reference marks are also provided at the four corners of the board (4) before solder printing. After the image (95) of this film (96) is taken in from the top of the film (96) by the image scanner (2), it is placed on the board (4) before solder printing, and the reference marks (99) are aligned.
As a result, the image (95) of the film (96) is correctly covered with the patterns (41) and (41a) of the board before solder printing, and the pattern (41) to be solder printed is hidden. The pattern (41a) that is not covered by the solder (40) is deleted at once.
Thereby, an image in which only the inspection target pattern (41) to be solder-printed exists is produced. The total areas of the respective patterns (41) are integrated and used as a master. Next, based on the master, an area ratio that is a criterion for determining the quality of the pattern (41) is set to 20%, for example.
Next, the pattern (41) image of the printed circuit board (4) after solder printing to be inspected is taken in by the image scanner (2), and the area of the pattern (41) on which the solder is not printed is obtained. The area of the pattern (41) is divided by the master to obtain the ratio of the pattern (41) remaining. If the pattern (41) remains beyond the area ratio that is a criterion for pass / fail judgment, it is judged that the solder is insufficient. Specifically, if the pattern (41) remains beyond the area ratio of 20%, it is determined that the solder is insufficient. If the area where the pattern (41) remains is 20% or less which is the area ratio, it is determined as a non-defective product.

As shown in FIG. 28 (b), when the image (95) of the film (96) is captured by the reading module (5), light is applied to the film (96). 97). Since the film (96) is thick, the shadow (97) is out of plane with respect to the image (95). Since the inspection of the pattern (41) inspects a deviation of about 20-40 microns, the influence of the deviation of the planar position is great.
Accordingly, the image of the photo data in the PC (10) is first mirror-inverted and printed on the film (96). As shown in FIG. 28 (c), if the burned image (95) is turned upside down so as to be on the lower surface of the film (96) and the image (95) is captured without capturing the shadow, the accuracy is high. Inspection can be performed. When capturing the image (95) of the upside down film (96), an unnecessary image or noise can be captured if a white plate (98) is placed under the film (96). Can be prevented.

(Third example of inspection image processing)
As in the past, the pattern (41) (41a) is generally made of copper, but in recent years, the gold pattern (41) (41a) has been used in view of low resistance, easy soldering, etc. May be. When the gold pattern (41) (41a) is irradiated with light and the image of the pattern (41) (41a) is captured by the reading module (5), it is contained in the solder (40) itself. There is also a color, and there is a possibility that the solder (40) and the patterns (41) (41a) cannot be distinguished.
Furthermore, the solder (40) is ambiguous due to surrounding colors and shadows. In view of this point, the applicant paid attention to a specific color of the solder (40). That is, RGB that is a solder specific color not including the color of the resist adjacent to the solder (40) and the pattern (40) (40a) is extracted, and the solder specific color scattered in the solder (40) is connected. The area where the solder (40) is printed is specified.
Specifically, as shown in FIG. 29, by performing binarization processing and noise processing on the image of the solder (40) taken in by the reading module (5), the solder specific color element (46) is surrounded by the surroundings. Compared to black. The area where the solder (40) is printed is estimated by enclosing all the elements of the solder specific color projected in black compared with the surrounding area with a virtual frame (45) indicated by a one-dot chain line. By dividing the area in the virtual frame (45) by the master, the ratio of the printed solder (40) is obtained. In the PC (10), an area ratio that is a criterion for determining whether or not the solder (40) is printed is set in advance.
If the area ratio in the virtual frame (45) is equal to or less than the area ratio, it is determined that the solder is insufficient. If the area ratio in the virtual frame (45) exceeds the area ratio, it is determined as a non-defective product.

In the above example, the inspection device for confirming the printed state of the solder (40) of the printed circuit board (4) is disclosed. However, the solder (40) in which the electronic component is mounted on the printed circuit board (4) or further cured in a reflow furnace. ) You may inspect the condition. Here, the state of the solder (40) to be inspected includes the presence / absence of solder (40), too small, too much, and a bridge. In addition, the mounting state of the electronic component to be inspected includes the presence / absence of the electronic component, misalignment, an error in the electronic component itself, and an error in polarity.
It is suitable for inspecting printed circuit boards (4) mounted with electronic parts, specifically thin electronic parts used for mobile phones, digital cameras, etc. The upper and lower sides of the printed circuit board (4) and the image reading unit (54) The interval is adjusted to about 7-9 mm which is the focal length of the image reading unit (54). The first means for finely adjusting the vertical interval and the inclination θ1 and the second means for adjusting the planar position and the angle θ2 of the image reading unit (54) are for adjusting the focal length and accurately reading the image. ,It is essential.
Further, a reflection plate (not shown) may be placed on the reading unit (54) of the image scanner (2) to brighten the image on the surface facing the illumination.
Moreover, you may use the test | inspection apparatus of this example for the test | inspection of the presence or absence of the adhesion of the shape of the hole (90) of a metal mask (9), position accuracy, and the hole (90) periphery. Moreover, you may test | inspect the precision of the board | substrate before printing.

  The above description of the embodiments is for explaining the present invention, and should not be construed as limiting the invention described in the claims or reducing the scope thereof. For example, as long as it is an appearance inspection object suitable for the present invention, it does not have to be related to electronic component mounting. In addition, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope described in the claims.

It is a front view which shows the outline of an inspection apparatus. It is a perspective view of an inspection device. It is a bottom view of an image scanner. It is sectional drawing which fractured | ruptured FIG. 2 in the surface containing an AA line. It is side surface sectional drawing which shows the other structure which supports a reading module horizontally. It is side surface sectional drawing which shows the other structure which supports a reading module horizontally. It is side surface sectional drawing which shows the other structure which supports a reading module horizontally. It is side surface sectional drawing which shows the other structure which supports a reading module horizontally. It is side surface sectional drawing of the image scanner of another Example. It is front sectional drawing of the image scanner which shows another Example. It is a top view which shows the image scanner in another Example. It is a top view which shows the test | inspection surface divided | segmented. It is a top view which shows the image scanner in another Example. It is a top view which shows the image scanner in another Example. It is a top view which shows the method of printing cream solder on a printed circuit board. (a), (b), (c) is a figure which shows the cream solder printed on the pattern. It is a block diagram which shows the conventional inspection apparatus. (a), (b) is a figure which shows the test | inspection principle of the test | inspection apparatus of FIG. It is sectional drawing of an image scanner. It is sectional drawing which shows the inside of a reading module. It is a top view which shows the printed circuit board before solder printing. It is a top view which shows the printed circuit board after solder printing. A state in which solder is printed on a part of a pattern on a printed circuit board after solder printing is shown. (a), (b) is a top view which shows a bridge state, (c), (d) is a top view which shows the bleeding state of a solder. (a), (b) is a top view which shows a solder printing misalignment state. (a) is side sectional drawing of the image scanner of another Example, (b) is the top view, (c), (d) is a top view which shows the scanning state of an image scanner. (a) is side sectional drawing of the image scanner of another Example, (b) is the top view, (c), (d) is a top view which shows the scanning state of an image scanner. (a), (b), (c) is explanatory drawing which shows the example of test | inspection image processing. It is a top view which shows the virtual frame surrounding all the elements of a solder specific color.

Explanation of symbols

(1) Inspection equipment
(2) Image scanner
(4) Printed circuit board
(5) Reading module
(11) Monitor
(21) Guide shaft
(40) Solder
(54) Image reader

Claims (15)

A reading module (5) that moves along at least one guide shaft (21) and scans an image with the image reading unit (54) facing downward, and a horizontal that supports the reading module (5) in a horizontal state An image scanner (2) provided with a support member, a conveying means for conveying an inspection object to the lower side of the image reading unit (54) of the image scanner (2), and an image scanned by the reading module (5) To provide a display on the monitor (11),
A transparent cover (24) is provided on the lower surface of the image scanner (2) so as to face the object to be inspected, and a protective cover (200) including the transparent cover (24) is provided on the outer side of the image scanner (2). Attached to the outside of the protective cover (200) is covered with a pair of stays (300) separated in the direction of conveyance of the inspection object,
The top surface of each stay (300) and the upper surface of the protective cover (200) are connected by two first adjusting screws (210) and (210) which are separated along the width direction of the image scanner (2). The vertical distance between the reading module (5) in the scanner (2) and the inspection object and the inclination of the reading module (5) with respect to the inspection object are determined by rotating the first adjusting screws (210) and (210). Tweaked,
A second adjustment screw (220) (220) is screwed onto the side surface of each stay (300) and the side surface of the protective cover (200), and by rotating the second adjustment screw (220) (220), An inspection device in which the plane position of the image scanner (2) is finely adjusted, and the image scanner (2) rotates slightly in a horizontal plane . 2. The inspection apparatus according to claim 1, wherein the scanning direction of the reading module (5) is substantially parallel to the conveyance direction of the inspection object or substantially orthogonal to the conveyance direction of the inspection object.   The image scanner (2) can be rotated upward or slidable about the pivot (60), and can be slid upward. After the inspection is completed, the image scanner (2) is rotated upward or slid backward to remove the inspection object. The inspection apparatus according to claim 1, wherein the inspection apparatus is opened so as to be removable.   A first stopper (320) and a second stopper (330) for stopping the inspection object are provided along the conveyance direction of the inspection object, and the first stopper (320) is stopped by one reading module (5). The inspection apparatus according to any one of claims 1 to 3, wherein the inspection apparatus scans a front end portion of the inspection object and a rear end portion of the inspection object stopped by the second stopper (330).   5. The inspection apparatus according to claim 1, wherein a plurality of reading modules (5) are provided in the image scanner (2), and the inspection surface of the inspection object is divided and read.   The inspection object is the accuracy of the board before solder printing, the presence / absence of electronic components mounted on the printed circuit board (4), misalignment, incorrect electronic components themselves, wrong polarity, presence / absence of hardened solder (40), too little The inspection device according to claim 1, wherein the inspection device is excessive, bridged. The inspection apparatus according to claim 1, wherein the inspection object is the shape and position accuracy of the hole (90) of the metal mask (9) and the presence or absence of solder scraps around the hole (90).   6. The inspection apparatus according to claim 1, wherein the inspection object is solder (40) or a pattern (41) printed on the printed circuit board (4). A means for recognizing a pattern of a board before solder printing, a means for recognizing a pattern of a board after solder printing, and a pattern of the board before solder printing and an image of the pattern after solder printing, and inspecting that solder is not printed A means for collectively deleting unexamined patterns and integrating the entire area after the solder printing that has not been deleted as a master, and a means for setting an area ratio as a pass / fail judgment criterion for a pattern to be inspected based on the master With
After setting the area ratio to be a determination criterion, the remaining area of the pattern after solder printing, which is the inspection target conveyed to the lower side of the image scanner (2), is obtained, and the ratio of the remaining area of the pattern to the master is The inspection apparatus according to claim 8, wherein a solder shortage is determined based on whether or not the area ratio is a criterion for determination. Means for recognizing the pattern of the board before solder printing, means for recognizing the image (95) of the film (96) created using the photo data in which the area to be solder printed is set, and the pattern of the board before solder printing And the image (95) of the film (96) are overlaid, the pattern not covered by the image (95) of the film (96) is deleted at once, and the area that is not deleted is integrated as the master Means, and means for setting an area ratio to be a quality determination criterion of the inspection target pattern based on the master,
After setting the area ratio to be a determination criterion, the remaining area of the pattern after solder printing, which is the inspection target conveyed to the lower side of the image scanner (2), is obtained, and the ratio of the remaining area of the pattern to the master is The inspection apparatus according to claim 8, wherein a solder shortage is determined based on whether or not the area ratio is a criterion for determination.   The inspection apparatus according to claim 10, wherein the photo data is mirror-reversed, and the image (95) is formed on the lower surface of the film (96). An inspection object in which the means for recognizing the pattern of the substrate before solder printing, the means for recognizing the pattern of the substrate after solder printing, and the pattern of the substrate before solder printing and the image of the pattern after solder printing are overlapped. A means to collectively delete areas outside the pattern and integrate the pattern images that were not deleted as a master,
After the area integration, the solder specific color is extracted from the solder print area on the pattern to be inspected that has been conveyed to the lower side of the image scanner (2), and the virtual frame (45) surrounding the solder specific color portion is extracted. The inspection apparatus according to claim 8, wherein an area of the solder printing region is estimated, and solder shortage is determined from a ratio between the estimated area of the solder printing region and the area of the master. Means for recognizing the pattern of the board before solder printing, means for recognizing the image (95) of the film (96) created using the photo data in which the area to be solder printed is set, and the pattern of the board before solder printing And the image (95) of the film (96) are overlaid, the pattern not covered by the image (95) of the film (96) is deleted at once, and the area that is not deleted is integrated as the master With means,
After the area integration, the solder specific color is extracted from the solder print area on the pattern to be inspected that has been conveyed to the lower side of the image scanner (2), and the virtual frame (45) surrounding the solder specific color portion is extracted. The inspection apparatus according to claim 8, wherein an area of the solder printing region is estimated, and solder shortage is determined from a ratio between the estimated area of the solder printing region and the area of the master.   The solder (40) means for noise processing the pattern image after printing, the noise-processed pattern image and the master image are superimposed, and adjacent inspection target patterns (41) (41) or solder (40) ( 40) The inspection apparatus according to claim 9 or 12, further comprising means for determining whether or not the two are connected by solder, and determining a bridge or a bridge device. The master image formed by the pattern of the board before solder printing and the image (95) of the film (96) and the pattern after printing of the solder (40) are overlapped, and adjacent inspection target patterns (41) (41) Or a means for determining whether or not the solders (40) and (40) are connected by solder or approaching each other, and a bridge or a bridge device is determined. The inspection apparatus in any one of.

Images