JPH08159981A - Method and apparatus for inspecting mounting state of component for external appearance inspecting machine - Google Patents

Abstract

PURPOSE: To effectively judge and to improve the inspecting capacity by distin guishing the criteria of inspecting positions by good, unclear and defective, and judging the propriety by the ratio of the number of the good and the un clear arbitrarily set when the inspected result includes the good and the unclear. CONSTITUTION: When soldering of an object (IC component) to be inspected is, for example, inspected, eight inspecting windows W3 to W10 are formed in the shape coincident with the lands to be soldered. The component mounting states are sequentially inspected from the window W3, and when the one which is judged to be defective of the eight windows W3 to W10, the component is judged to be defective mounting (or defective component). If the entirety is good from the judged results, the good component is decided. However, when the intermediate state in which the component which is not defective but can not to be judged to be good, occurs, the window is set to unclear, and if the other judged result is good, the components are judged to be good by decision by majority. For example, if five are good but three are defective, the good is judged, and when all the windows W3 to W10 are judged to be unclear, the defective is judged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for inspecting the mounting state of electronic components on a printed wiring board or the like based on their appearance.

[0002]

2. Description of the Related Art FIG. 6 shows a basic system configuration diagram of a component attachment state inspection device for inspecting solder joints of electronic components on a printed wiring board.

In FIG. 1, the television camera 30 receives reflected light from the illuminator 20 through the inspection object 60.
Based on the pattern of this video signal, the recognition processing unit 50 is inspected for missing items, misalignment, and chip standing (in chip parts,
It refers to the case where the side surface is bonded to the original bonding surface. This is likely to occur in the case of a component such as a chip capacitor whose length in the vertical direction is close to that in the horizontal direction. ) Etc., the quality of the mounting state of the parts is judged.

An example of a method for inspecting a soldered joint when the inspection target component is a rectangular chip component will be described. FIG. 7 shows a model diagram when the rectangular chip 1 of the inspection target component is viewed from above. Thus, in the case of the rectangular chip component 1, it can be seen that there are two soldering portions 2 for one component. For example, the inspection of this component is performed by inspecting the soldering state at each of two places where soldering is performed, and determining the quality of soldering of the inspection target component and the mounting state of the component such as a missing item from the result. It will be.

FIG. 8 is a flow chart of the inspection process in the case of inspecting the mounting state represented by the missing parts of electronic parts.
Shown in

First, an image in the visual field of the television camera 30 including the inspection target portion 60 is taken. In the inspection of the attachment state of the target component rectangular chip 1 of FIG. 7, the quality of the inspection windows W1 and W2 set in the soldering portion 2 is determined. In the case of this example, the attached window W1
Is used to make a pass / fail judgment, and then the attached window W2 is also used to make a pass / fail judgment. This is done for a window corresponding to all electrodes in a component such as an IC having a large number of electrodes.

In this way, after all the windows attached to the parts are judged to be good or defective (missing parts, displacement, chip standing, etc.), the final quality judgment of the parts to be inspected is attached to the parts. The judgment results of all the windows are examined, and if a defect is detected even at one place, the product is defective, and only if the judgment results of all the windows are good, the product is good.

[0008]

As described above, the conventional inspection apparatus determines whether the soldering inspection of the target component is good or bad for each inspection window. Therefore, even if the determination is difficult, it is necessary to make a determination as to whether it is good or not, so it is difficult to set the determination standard.Furthermore, in order to prevent erroneous determination that a defective product is a good product, from the concept of fail-safe, The judgment criteria must be strict.

For this reason, there are many false alarms that are judged to be defective even if they are actually good products, and such erroneous judgments occur in about 0.3% in an actual example, and there are many mounted parts in particular. This is a factor that significantly lowers the inspection capability of printed circuit boards.

Therefore, in the present invention, based on the inspection results of all the inspection windows attached to the component, comprehensive determination is made to determine the positional deviation of the target component, defective product, chip standing, etc., and the inspection capability is improved. The purpose is to

[0011]

[Means for Solving the Problems] When the above false information is analyzed in detail, most of the windows that have been judged to be defective are actually not clear defects but are in the gray zone, and
Most of them turned out to be good products.

In view of the above-mentioned problems, the present invention solves the above-mentioned problems by determining "unknown" in addition to "good" and "defective" for each window, and further determining the object to be inspected. Each of the attached windows, accumulates the determination result, based on the inspection result of the inspected part, performs a determination by comprehensive majority processing based on the number of "unknown" determination in each part, the Based on the result, it is possible to judge the mounting state such as missing parts.

[0013]

As described above, according to the present invention, the portion of the inspection target component that is difficult to determine is unknown, and the inspection result of the good or defective of the target component is determined based on the number of unknowns in each target component. Of course, if all the inspection points are good, the inspection target component is a good item, and if there is a missing item even at one point, it is determined as a defective item. With such an inspection method, it is possible to accurately determine whether or not a wrong determination has been conventionally made, and the inspection capability is improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method and apparatus for inspecting the mounting state of parts in an appearance inspection machine of the present invention will be described with reference to the flow chart of FIG. The parts to be inspected below are shown in FIG.
As an example, the inspection of the mounting state of the IC component as shown in FIG. The overall external configuration of the device is the same as in FIG.

The light projected from the illuminator 20 is the inspection object 6
The reflected light is reflected at 0, and the reflected light is received by the television camera 30.
It is assumed that the image thus obtained is as shown in FIG. In the soldering inspection of the target 60 (IC component), the land to be soldered is set, and thus the inspection windows W3 to W10 are created in a shape that matches this land. Therefore, in this example, the inspection target component 6
For every one, there are eight inspection windows.

First, the mounting state of the components is inspected in the inspection window W3, and then the inspection window W4, and in the same manner, the respective windows from W5 to W10 are inspected.
As a result, if all of the windows are good, a non-defective flag is set, and if the items are obviously out of order or misaligned, a defective flag is set. Here, when an intermediate state which cannot be judged as good is generated although it is not judged as defective, the judgment of the inspection window is made unknown, and only the unknown flag is set to proceed to the next inspection.

It should be noted that such judgment of good, defective, and unknown may be performed by a well-known pattern comparison, for example, by measuring the length of a component in the window and comparing it with a reference value.

In the above example, if at least one of the 8 inspection windows attached to the component to be inspected is determined to be defective, the component is determined to be defective (or missing). If all the judgment results are good,
Good product. However, if there is a result that is determined to be unknown among these, and if the other determination results are non-defective, the target component is determined to be non-defective by a majority process. For example, if 5 out of all the windows are good, it is judged as a good product even if the other 3 windows are unknown.

However, when it is determined that all 8 windows are unknown, the parts are determined to be defective in order not to overlook defective products.

When the number of windows determined to be non-defective is X and the number of windows determined to be unknown is Y, when the number of X is larger than Y (X> Y), the number of non-defective is good and the number of Y is equal to X, or , (X ≦ Y), it is determined to be defective (part mounting state is defective).

In other words, the judgment formula is the judgment value (Z) = X / (X + Y) × 100, and when Z is 50% or more, it is judged as good product, and when Z is 49% or less, it is judged as defective product. Note that this determination value is an example, and does not necessarily have to be 50%, and the detection accuracy of the device, the method of determining the determination standard, and the false alarm rate (determination for determining a non-defective product as a defective product) are set to what extent. Needless to say, it also varies depending on the situation.

That is, when it is desired to reduce the false alarm rate, the determination value Z is set low, and from the standpoint of fail-safe, the determination value Z is set high.

As described above, when it is difficult to make a distinction by the inspection in each inspection window, an unknown determination is made, and the soldering inspection of the target component is made by synthesizing the inspection results of each inspection window.

Next, a description will be given of an embodiment in which the present invention is used in an inspection device using a multi-stage lighting device. Regarding the multi-stage lighting inspection method, the basic principle is Japanese Patent Publication 5-21.
403. As an example of this, FIG. 3 shows a basic system configuration diagram of a multi-stage lighting soldering inspection apparatus.

In the figure, illuminators 2 having different light projection angles are used.
0, the reflected light is received by the television camera 30 from the illuminator 21 via the inspection target 60. The code generation unit 40 generates a tilt code pattern indicating the angular distribution of the combination target parts from the respective video signals obtained by switching the illumination at each stage. The inclination code pattern thus obtained shows the soldering state of each inspection location, and naturally, the status of the out-of-stock product can also be known from this pattern. As shown in FIG. 1, the image recognition processing unit 50 recognizes the three-dimensional shape of the inspection object, determines the mounting state of the component, and determines the quality of the solder state.

Incidentally, since such code generation is well known, detailed description thereof will be omitted here. For example, JP-A-4-301549, JP-A-4-346011, JP-A-5-301549 and JP-A-6- 66528 and the like.

The tilt codes generated are, for example, codes 1 to 5, and each code represents the angle of the target surface. Code 1
Indicates the flat name portion, and the code 5 indicates the steepest angle. The angles increase from code 1 to 2, 3, 4, and 5 in that order. For example, as shown in FIGS. 5a and 5b, the states of the parts in the window are coded and displayed. In the figure,
a is a generated code of the window W0, and b is a cross-sectional view of the chip component 2 corresponding to a. 2a is an electrode, 3 is a solder part, and 4 is a printed circuit board surface. When the step illuminator is used as in this embodiment, the quality of each window is determined from the pattern of the angle code in the inspection window.

In this embodiment, XPAK having three soldered parts is taken as an example of a component to be inspected. TV camera 30 in a direction perpendicular to the inspection object
FIG. 4 shows a model in which the video signal received by the camera is generated with a tilt code. The XPAK has three attached inspection windows, W01 to W03, which are soldering portions. However, as in the case of a rectangular chip component, the inspection portion has a soldering state or a soldering condition in each inspection window. The mounting state of the component is determined by the inclination code. The inspection result of each window, that is, any one of the good, the bad, and the unknown is input to the good / bad determination unit (see FIG. 1) of the component.

Here, if all the judgments in the inspection window are good, the mounting state of the parts including soldering is judged to be good. In addition, if there is any abnormality in the determination of the inspection window, it is determined as a defective product. Also, if it is determined that all windows are unknown, it will be out of stock in order not to miss defective products in inspection. In the case of remaining unknowns and non-defective products, if the unknown number Y is equal to or greater than the number X of non-defective products, it is determined that the mounting state of the component is defective. If the unknown number Y is less than the number X of non-defective products, it is determined to be non-defective. This is as described in the above equation.

In the actual measurement data of the inspection result when this step illumination inspection machine is used, the error judgment, that is, the false alarm was 0.3% in the past, but it was improved to 0.1% in this embodiment.

Of course, this criterion is only an example, and may be changed depending on the inspection method of each inspection device and the type of target parts.

[0032]

EFFECTS OF THE INVENTION Even if the automatic inspection machine determines that the product is defective,
As a result of the re-inspection, it is necessary to visually re-inspect what is judged to be a non-defective product, that is, all of the products that have been determined to be defective products due to many false reports. Since the visual inspection is performed using a magnifying glass, the work efficiency is significantly deteriorated. In the worst case, the merit of the inspection by the automatic inspection machine that does not require direct human labor is lost.

However, according to the present invention, false alarms are remarkably reduced. Therefore, it is almost unnecessary to re-inspect an object which is found to be defective as a result of being inspected by the apparatus of the present invention.

Furthermore, according to the present invention, even if there is a portion that is difficult to discriminate, it is possible to accurately judge the quality by the majority process, and the inspection ability is remarkably improved.

The majority decision or the unknown decision of the present invention does not require any special hardware modification and can be realized by a simple software change, which has a cost advantage.

[Brief description of drawings]

FIG. 1 is a flowchart of a defect determination method according to the present invention.

FIG. 2 is a model diagram of an IC component for explaining an embodiment of the present invention when viewed from above.

FIG. 3 is a basic device configuration diagram of a multi-stage illumination type visual inspection device according to an embodiment of the present invention.

FIG. 4 is a model diagram when XPAK is viewed from above.

FIG. 5 is an explanatory diagram of code patterns according to the embodiment of the present invention.

FIG. 6 is a basic device configuration diagram showing a general configuration of an inspection device.

FIG. 7 is a model diagram when the chip part is viewed from above.

FIG. 8 is a flowchart of a defect determination method showing a conventional technique.

[Explanation of symbols]

1 square chip parts, 2 chip parts, 3 solder parts,
20, 21 Illuminator, 30 TV camera, 40 Code signal generator, 50 Image recognition processor, 60 Inspection target,
W1-W10 Wind, W01 Wind, W01-
W03 Wind,

Claims (3)

[Claims] 1. An apparatus for imaging an inspection target and inspecting a mounting state of a component based on the obtained image information, and when there are a plurality of inspection locations for each component to be inspected, it is acceptable to judge pass / fail of each location, If there are three stages, unknown and defective, and if at least one of the inspection points is defective, the determination is a defective product, and if all of the inspection points are good, it is a good product, and the inspection result of the inspection point is A method for inspecting the mounting state of parts in a visual inspection machine, characterized in that, when both good and unknown are included, the quality is judged by a ratio between the number of good and the number of unknowns set arbitrarily. 2. An apparatus for inspecting a mounting state of a component based on image information obtained by capturing an image of the inspection target, and when there are a plurality of inspection points for each component to be inspected, it is good to judge pass / fail of each part, If there are three stages, unknown and defective, and if at least one of the inspection points is defective, the determination is a defective product, and if all of the inspection points are good, it is a good product, and the inspection result of the inspection point is A method for inspecting the mounting state of parts in an appearance inspection machine, characterized in that when good and unknown are included, when the number of good is greater than the number of unknown, it is judged as good. 3. An apparatus for inspecting a mounting state of a component from image information obtained by capturing an image of an inspection target, wherein a plurality of sets of illuminators having different projection angles to the inspection target are switched and irradiated, A light receiving sensor that receives the reflected light from the inspection object by the light source as a reflected light luminance distribution from the inspection object and converts it into an electric signal and outputs it. The generated code generator and the code information of the inspection target portion are extracted from the code pattern generated by the code signal generator by the window corresponding to each part, and classified into at least three stages of good, unknown and bad for each window. If the inspection means to be inspected and at least one position of each window are defective, the printed circuit board to be inspected is determined to be a defective product, and if all are good, it is determined to be a good product. In a visual inspection machine characterized by having a pass / fail judgment means for judging pass / fail of each part based on a ratio of good / unknown if the inspection result includes good / unknown for one part mounted on a printed circuit board. Device mounting condition inspection device.