JPH07104937B2 - Visual inspection method for mounted parts - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mounting component appearance inspection method for inspecting the appearance of a component mounted on a printed wiring board, for example, a chip component is mounted. It is used to automatically inspect the mounting state and soldering state of components on a printed wiring board.

(Background Art) Conventionally, in order to inspect the appearance of a component mounted on a printed wiring board, as shown in FIG. 6 (a), soldering is performed on the component (8) on the printed wiring board (7). Illumination for illuminating the portion (9) is performed, and the image signal obtained by imaging the component mounting surface with a television camera or the like is binarized, and as shown in FIG. 9 ') is detected and the sixth
As shown in FIG. 6 (c), the vertical deviation inspection area (10) and the lateral deviation inspection area (11) are set, and measurement is performed in each area (10) and (11) to shift the component (8). Is also measured, and the out-of-stock inspection area (12) is set, and the color in the area (12) is measured, and the presence or absence of the out-of-stock article is determined by the color difference between the component (8) and the board (7). Was inspecting. As described above, an apparatus for binarizing an image signal obtained by picking up an image of a component mounting surface with a television camera or the like and inspecting the appearance of the mounted component is disclosed in, for example, Japanese Patent Laid-Open No. 58-139278. There is.

However, there are various kinds of soldering states. For example, if there is a solder deficient portion (9A) and a solder excess portion (9B) as shown in FIG. As shown in the figure, the images (9A ') and (9B') of the soldered portion cannot be accurately binarized, and there is a problem that an error occurs in the displacement measurement of the component (8). Further, as shown in FIG. 8 (a), when the mounting component (8) has characters (13) and trimming (14), an image as shown in FIG. 8 (b) is obtained and soldering is performed. The image (9 ') of the portion and the images (13') and (14 ') other than the soldered portion are confusing, which sometimes makes measurement difficult. Further, when the white silk is printed on the board (7) or the white board color is exposed like a ceramic board, the color of the mounting component (8) is similar to the color of the board (7). It was difficult to measure even while doing.

Therefore, for example, as disclosed in Japanese Patent Application Laid-Open No. 60-15780, it may be possible to recognize a target object by using a range image signal, but there are too many or too few parts on the printed wiring board. If a foreign object is mixedly mounted, or a component other than the component to be originally mounted is mounted, the foreign substance is detected even if the distance image signal is used. In that case, the mounting position and mounting direction of foreign matter should not be the same as that of a good product, and even if they are the same, the printed wiring board will still be a defective product as a whole. It just makes the people prolong their inspection time.

(Object of the Invention) The present invention has been made in view of the above points,
The purpose is that if there are too many or too few components mounted on the printed wiring board, or if there is foreign matter mixed mounting such as components other than the components that should be originally mounted, the mounting position of the mounted components or An object of the present invention is to provide a visual inspection method for a mounted component, which is capable of simplifying the inspection work by excluding the mounting direction from the original visual inspection work for comparing with a non-defective product.

DISCLOSURE OF THE INVENTION In the present invention, the distance image of a plurality of components mounted on the printed wiring board is detected by the distance image detecting unit, and then the detected distance image is labeled by the separation recognition unit. , It is judged whether or not there is a candidate corresponding to a non-defective product for each labeled land, and if there is no candidate, the primary judgment is made that foreign substances are mixed, and if there is a candidate, it is an appearance inspection of the mounted parts. It is characterized in that a secondary determination is made to perform label correspondence with non-defective products.

FIG. 1 shows the construction of an apparatus for carrying out the method of the present invention. In the figure, (1) is a distance image detection unit for detecting distance images of a plurality of components mounted on the printed wiring board (7). (2) is a binarization processing unit that binarizes the distance image detected by the detection unit (1) at a threshold level such that only parts are extracted. (3) is a separation recognition unit that performs separation recognition of components from the binarized image obtained by the binarization processing unit (2). (4) is a component feature amount calculation unit that calculates the feature amount of the separately recognized components.
(5) is a non-defective item feature amount storage unit that holds the feature amount calculated in advance for non-defective items. Further, (6) is a comparison / determination unit that compares the respective feature amounts of the component feature amount calculation unit (4) and the non-defective item feature amount storage unit (5) to perform pass / fail determination.

FIG. 2 shows how the distance image is detected by the distance detector (1). In FIG. 2, the height of each point on the board (7) on which the component (8) as shown in FIG. 3 (a) is mounted by using the optical distance detection unit (1) by triangulation. Is being measured. Then, the board (7) or the distance detection unit (1) is scanned in the X direction and the Y direction using an XY stage or the like to form a distance image of the board (7) on which components are mounted. The image signal is binarized so that only the shape of the component (8) appears white (or black) from this distance image, and a binarized image as shown in FIG. 3 (b) is obtained. Using this binarized image, each component image (8 ') is separately recognized and labeled. An example of the labeled state is shown in FIG. Then, for each labeled land (white or black mass having connectivity), as shown in FIG.
A feature amount such as a center of gravity, an area, a circumscribed quadrangle, and a principal axis of inertia is calculated. Then, the characteristic amount of the non-defective substrate calculated in advance is compared.

A specific flow of inspection will be described with reference to the flowcharts of FIGS. First, as shown in FIG. 5 (a), a distance image of a board on which components are mounted is input, the input image signal is binarized, and each land in the binarized image is labeled and separately recognized. Then, after performing area filtering, the feature amount calculation of each land is performed. When the feature amount calculation is completed, all distances between the center of gravity of the labeled land and the center of gravity of the non-defective product are obtained. The center-of-gravity distance Rnm between the inspection land (n) and the non-defective land (m) is calculated by the following equation.

However, (Xng, Yng) is the barycentric coordinate of the inspection land (n),
(Xmg, Ymg) are the barycentric coordinates of the non-defective land (m).

Next, as shown in FIG. 5 (b), if the center-of-gravity distance Rnm is within a predetermined standard, it is stored as a candidate corresponding to a non-defective product, and if there is no candidate, it is determined to be out of stock. . If there is one inspection land (n) corresponding to the non-defective product land (m), the label is associated with the non-defective product, and if there are multiple inspection lands (n), the evaluation function αnm of the following equation is calculated.

However, An is the area of the inspection land (n), and Am is the area of the inspection land (m). Rmean is expressed by the following equation.

Rmean = Σ (min Rnm ′) / K In the above equation, Rnm ′ is the standard distance, and Σ (min Rnm ′)
nm ') is the sum of the minimum values. Also, K is a distance of 1:
It is the number of non-defective products associated with 1.

Labels with α nm within specifications are associated with non-defective products, and other products are determined to be mixed with foreign matter. When this method is used, it is possible to make a determination even if the positioning accuracy of the substrate at the time of inspection is rough, and complicated processing is unnecessary.
The following formula may be used as a simpler formula for the evaluation function.

αnm ′ = (Rnm−Rmean) + An / Am Next, regarding the associated land, FIG. 5 (c)
As shown in, the area comparison is performed, and if An >> Am, it is judged as "part error" or "bridge", and if An << Am, it is judged as "part standing" or "part missing". If so, check the bounding box. If the circumscribed quadrangle is not within the preset range, it is determined as "part shift". Next, by looking in the direction of the principal axis of inertia, it is determined whether or not there is "part inclination". If the conditions such as the area, the circumscribed quadrangle, and the principal axis of inertia are the same as those of the non-defective product, the product is determined to be the non-defective product.

(Effect of the invention) As described above, in the present invention, the distance image detecting unit detects the distance images of a plurality of components mounted on the printed wiring board, and the detected distance images are detected by the separation recognition unit. After labeling, it is judged whether or not there is a candidate corresponding to a non-defective product for each labeled land, and if there is no candidate, the primary judgment is made that foreign substances are mixed, and if there is a candidate, the appearance of the mounted component Since the secondary judgment is performed by associating labels with non-defective products to be inspected, it is possible to make judgment even if the positioning accuracy of the board during inspection is rough, and there are too many parts on the printed wiring board. In addition, if there is foreign matter mixed mounting that is mounted excessively or insufficiently, or if a component other than the component to be originally mounted is mounted, there is an effect that the inspection work can be simplified by excluding it from the visual inspection work.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of the present invention, FIG. 2 is a perspective view showing a distance image detecting section used in the same as above, and FIGS. 3 (a) to 3 (c) are operation explanatory diagrams of the same as above, and FIG. Is an explanatory view for explaining the characteristic amount of the mounted component used in the above, FIG.
FIGS. 6 (a) to 6 (c) are flowcharts showing the operation of the above embodiment, FIGS. 6 (a) to 6 (c), and FIG. 7 (a).
FIGS. 8B and 8A and 8B are explanatory views for explaining a conventional inspection method. (1) is a distance image detection unit, (2) is a binarization processing unit,
(3) is a separation recognition unit, (4) is a component feature amount calculation unit,
(5) is a non-defective item feature amount storage unit, (6) is a comparison determination unit,
(7) is a substrate and (8) is a component.

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area H05K 13/08 D 8315-4E

Claims (3)

[Claims] 1. A distance image detecting unit detects distance images of a plurality of components mounted on a printed wiring board, and the detected distance images are labeled by a separation recognizing unit for each labeled land. It is determined whether there is a candidate corresponding to the non-defective product, and if the candidate does not exist, the primary judgment is made that the foreign matter is mixed, and if there is the candidate, the label is associated with the non-defective product, which is the appearance inspection of the mounted component. A method for inspecting the appearance of mounted parts, which comprises performing a secondary judgment. 2. A binarization process of binarizing a range image detected by a range image detection unit at a threshold level such that only parts are extracted, and then separating and recognizing parts from the obtained binarized image. The appearance inspection method for a mounted component according to claim 1, wherein: 3. A feature amount such as the center of gravity or area of a separately recognized component is calculated, and a label is associated with a non-defective product by using an evaluation function, and the center of gravity, area, circumscribing quadrangle, and principal axis direction of inertia of each component are determined as non-defective products. The appearance inspection method of the mounted component according to claim 2, wherein the appearance inspection of the mounted component is performed in comparison with.