TWI848618B - Pcb defect detection method, metrological measurement method and manufacture method for circuit board - Google Patents

Abstract

The present disclosure provides a PCB defect detection method, a metrological measurement method and a manufacture method for circuit board. The detection method comprises: inputting a PCB design document of a circuit board to be detected into an AOI device, wherein the PCB design document comprises designed dimension information of each object on the circuit board; scanning the circuit board to obtain a scanned image by the AOI device, and obtaining a pixel unit dimension currently set by the AOI device; in response to a trigger signal of a detection request for at least one target object, determining a number of pixels occupied by the target object in the direction of requesting measurement in the scanned image; according to the pixel unit dimension currently set by the AOI device and the number of pixels occupied by the target object, calculating a dimension of the target object in the direction of requesting measurement; comparing the dimension of the target object in the direction of requesting measurement with the dimension information of the target object in the design document; if a dimension difference thereof exceeds a preset difference threshold, it is determined that the target object of the circuit board is defective.

Description

PCB defect detection method, circuit board measurement method and manufacturing method

The present invention relates to the field of PCB detection, and in particular to a PCB defect detection method, a circuit board measurement method and a manufacturing method.

Automated Optical Inspection (AOI) equipment has now become an important inspection tool and process quality control tool for the electronics manufacturing industry to ensure product quality. It is equipped with a line scan camera to perform a line scan on the circuit board, and then the sub-images of the line scan are spliced to obtain a complete PCB scan image.

The conventional means of PCB defect detection is that the AOI equipment compares the inspection points with the qualified parameters in the database, and detects the defects on the tested product through image processing.

However, the current AI detection model lacks accuracy, resulting in frequent detection errors, which affects the accuracy of defect identification.

The disclosure of the above background technology content is only used to assist in understanding the invention concept and technical solution of the present invention. It does not necessarily belong to the prior art of this patent application, nor does it necessarily provide technical guidance. In the absence of clear evidence that the above content has been disclosed before the application date of this patent application, the above background technology should not be used to evaluate the novelty and creativity of this application.

The purpose of the present invention is to provide a PCB defect detection method, a circuit board metrology measurement method and a manufacturing method, which utilizes the scanning image of the AOI equipment to quickly perform two-dimensional metrology on the object on the PCB, and utilizes the circuit board metrology measurement data as the basis for detecting circuit board defects, thereby improving the accuracy of defect detection and identification.

To achieve the above object, the technical solution adopted by the present invention is as follows:

A PCB defect detection method, comprising:

Inputting the PCB design document of the circuit board to be inspected into the AOI equipment, wherein the PCB design document includes the size design information of each object on the circuit board;

Scanning the circuit board to be inspected by the AOI device to obtain a PCB scan image and obtain the pixel unit size currently set by the AOI device;

In response to a trigger signal of a detection request for at least one target object, determine the number of pixels occupied by the target object in the PCB scan image in the requested measurement direction;

According to the pixel unit size currently set by the AOI device and the number of pixels occupied by the target object in the requested measurement direction, the size of the target object in the requested measurement direction is calculated by multiplying the two;

Compare the calculated result of the size of the target object in the requested measurement direction with the size design information of the target object in the PCB design document. If the size difference exceeds a preset difference threshold, it is determined that the target object of the circuit board has a defect.

Furthermore, the trigger signal for a detection request for a target object includes:

The PCB scanned image and the corresponding PCB design image in the PCB design document are input into the two-dimensional measurement software for display in advance;

Mapping and associating the PCB scan image with the PCB design image;

A target object is selected on the display interface of the PCB scan image, and a measurement direction is determined; and a mapping object associated with the selected target object in the PCB design image is determined.

Furthermore, the trigger signal for a detection request for a target object includes:

The PCB scanned image and the corresponding PCB design image in the PCB design document are input into the two-dimensional measurement software for display in advance;

Mapping and associating the PCB scan image with the PCB design image;

Selecting a mapping object associated with the target object mapping on the display interface of the PCB design image; and determining the target object associated with the selected mapping object in the PCB scan image, and determining the measurement direction.

Further, in response to a trigger signal of a defined area detection request, all target objects in the defined area are located and their respective measurement directions are determined, and the number of pixels occupied by each target object in the respective measurement direction in the PCB scan image is determined;

The size of each target object in the requested measurement direction is calculated according to the currently set pixel unit size and the number of pixels occupied by each target object in the defined area.

Further, the target object is a straight line segment or a curved line segment, and the corresponding requested measurement direction is the line segment length extension direction or line width direction; or,

The target object is a polygon, and the corresponding requested measurement direction is the edge length direction; or,

The target object is circular, and the corresponding requested measurement direction is the radial direction.

Further, if the size difference exceeds a preset difference threshold, the process type of the target object is determined according to the PCB design document;

The process parameters are modified for the determined process type so that the size difference between the measured size of the target object of the circuit board manufactured by the modified process and the size design information in the PCB design document is reduced.

Furthermore, if the measured line width of the bonding wire on the circuit board to be inspected is smaller than the corresponding size design information, the etching time process parameter is reduced;

If the measured line width of the bonding wire on the circuit board to be inspected is larger than the corresponding size design information, the etching time process parameter is increased.

Furthermore, the PCB scan image is a grayscale image or a color image.

Furthermore, during the scanning process of the AOI device, the number of pixels occupied by each scanned object on the circuit board in the requested measurement direction in the PCB scan image is counted until the scanning is completed, and the number of pixels occupied by all objects on the circuit board in the requested measurement direction in the PCB scan image and/or the size of all objects in the requested measurement direction are obtained.

Furthermore, the number of pixels occupied by each scanned object on the circuit board in the PCB scan image in the requested measurement direction is counted in the following manner:

Locate the starting point of the target object in its measurement direction, with a count of 1;

Step to the next pixel block in the measuring direction. If the grayscale value difference between the current pixel block and the pixel block in the previous step exceeds the preset grayscale threshold, then stop counting and stop stepping. Otherwise, the count is incremented by 1.

Repeat the step of stepping to the next pixel block in the measuring direction until the grayscale value difference between the current pixel block and the pixel block in the previous step exceeds the preset grayscale threshold, and then use the current counting result as the number of pixels occupied by the target object in the PCB scan image in its measuring direction.

According to another aspect of the present invention, a printed circuit board 2D metrology measurement method is provided, comprising:

Obtaining a PCB scan image obtained by scanning a target circuit board by an AOI device, and obtaining a pixel unit size currently set by the AOI device;

Select one or more target objects in the PCB scan image and determine the measurement direction thereof;

Determining the number of pixels occupied by the target object in the PCB scan image in the respective corresponding measurement directions;

According to the pixel unit size currently set for the AOI device and the number of pixels occupied by the target object in the requested measurement direction, the size of the target object in its measurement direction is calculated by multiplying the two.

Further, the number of pixels occupied by a target object in the PCB scan image in its measurement direction is determined by:

Locate the starting point of the target object in its measurement direction, with a count of 1;

Step to the next pixel block in the measuring direction. If the grayscale value difference between the current pixel block and the pixel block in the previous step exceeds the preset grayscale threshold, then stop counting and stop stepping. Otherwise, the count is incremented by 1.

Repeat the step of stepping to the next pixel block in the measuring direction until the grayscale value difference between the current pixel block and the pixel block in the previous step exceeds the preset grayscale threshold, and then use the current counting result as the number of pixels occupied by the target object in the PCB scan image in its measuring direction.

Furthermore, the printed circuit board 2D metrology measurement method further comprises:

Mapping and associating the PCB scan image with the PCB design image in the design document of the target circuit board;

Determine a mapping object associated with the selected target object in the PCB design image;

Determining the size design information of the mapping object in the design document;

The difference between the calculated size of the target object in its metrological direction and the size design information of the mapped object in the design document is subtracted to obtain the metrological measurement result of the target object.

According to another aspect of the present invention, there is provided a method for manufacturing a printed circuit board, comprising:

Set various initial process parameters according to the design documents of the circuit board;

Producing a circuit board to be verified according to the initial process parameters;

Utilizing the PCB defect detection method as described above to detect the circuit board;

If it is determined that the circuit board does not have defects, batch production is carried out according to current process parameters;

Otherwise, the process type of the object with defects is determined according to the PCB design document; the process parameters of the determined process type are corrected so that the size difference between the measured size of the target object of the circuit board manufactured by the corrected process and the size design information in the design document is reduced.

The beneficial effects brought by the technical solution provided by the present invention are as follows:

a. Perform two-dimensional metrology measurement of circuit boards on the scanned images of the circuit boards by the AOI equipment without the need for additional tools such as cameras;

b. During the AOI scanning process, the number of pixels occupied by the target object in the PCB scan image in the requested measurement direction can be counted. After the AOI scanning is completed, the two-dimensional measurement result data of the circuit board can be quickly obtained without affecting the AOI inspection process itself, which greatly improves the efficiency of the AOI cycle;

c. The scanned image of the AOI equipment is formed by stitching the images taken by the line scan camera, so that compared with the limited pixels of the camera, the scanned image theoretically has an unlimited number of measurement points.

In order to enable people in the technical field to better understand the scheme of the present invention, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technical personnel in the field without creative labor should belong to the scope of protection of the present invention.

It should be noted that the terms "first", "second", etc. in the specification and scope of the invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, device, product or equipment that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or equipment.

In one embodiment of the present invention, a PCB defect detection method is provided, referring to FIG1 , the defect detection method comprises:

Inputting the PCB design document of the circuit board to be inspected into the AOI equipment, wherein the PCB design document includes the size design information of each object on the circuit board;

Scanning the circuit board to be inspected by the AOI device to obtain a PCB scan image (which can be a grayscale image or a color image), and obtaining the pixel unit size currently set by the AOI device;

In response to a trigger signal of a detection request for at least one target object, determine the number of pixels occupied by the target object in the PCB scan image in the requested measurement direction;

According to the pixel unit size currently set by the AOI device and the number of pixels occupied by the target object in the requested measurement direction, the size of the target object in the requested measurement direction is calculated by multiplying the two;

Compare the calculated result of the size of the target object in the requested measurement direction with the size design information of the target object in the PCB design document. If the size difference exceeds a preset difference threshold, it is determined that the target object of the circuit board has a defect.

In this embodiment, the PCB scan image and the corresponding PCB design image in the PCB design document are input into the two-dimensional measurement software for display in advance, as shown in FIG3 , in which the upper part of FIG3 is the PCB design image and the lower part is the PCB scan image;

In the two-dimensional measurement software, the PCB scan image is mapped and associated with the PCB design image, that is, selecting an object in the PCB scan image can be mapped to the corresponding object in the PCB design image, and vice versa, selecting an object in the PCB design image can be mapped to the corresponding object in the PCB scan image.

In one embodiment of the present invention, the trigger signal for a detection request for a target object is: selecting the target object on the display interface of the PCB scan image and determining the measurement direction; and determining the mapping object associated with the selected target object in the PCB design image.

In another embodiment of the present invention, the trigger signal for a detection request for a target object is: selecting a mapping object associated with the target object mapping on the display interface of the PCB design image; and determining the target object associated with the selected mapping object in the PCB scan image, and determining the measurement direction.

In short, the target object can be a line segment, a circular area or a polygonal area in the PCB scan image, etc. For example, you can select a target object by single clicking, multi-clicking or right clicking, or indirectly select the target object in the PCB scan image by selecting the mapping object in the PCB design image.

Different target objects can have different measurement directions. For example, if the target object is a straight line segment or a curve segment, the corresponding requested measurement direction is the segment length extension direction or the line width direction; if the target object is a polygon, the corresponding requested measurement direction is the edge length direction; if the target object is a circle, the corresponding requested measurement direction is the radial direction.

As shown in Figure 3, the selected target object is a straight line segment, and the requested measurement direction is the line width direction. In the Measurement pop-up window in Figure 3, it can be seen that the line width of the 2D measurement in the PCB scan image is 3.59 um, and the size design information (Reference) of the corresponding mapping object in the PCB design image is 4.6 um, and the size difference (Difference) is -1.01 um. For example, the default difference threshold is 0.5um, which means that the range of ±0.5um of the Reference size is within the tolerance range. If it exceeds the tolerance range, the process parameters of the target object need to be corrected so that the size difference between the measured size of the target object of the circuit board produced by the corrected process and its size design information in the PCB design document is reduced. For example, in Figure 3, the line segment adopts the etching process. If the line width measured by 2D is smaller than the Reference size, it means that the etching is excessive, and the etching time process parameter should be reduced; on the contrary, if the line width measured by 2D is larger than the Reference size, it means that the etching is not in place, and the etching time process parameter should be increased.

In one embodiment of the present invention, multiple target objects can also be measured in batches in two dimensions. The specific steps are to use an input device such as a mouse to mark an area in the PCB scan image, and similarly associate and map the mapped area in the PCB design image to locate all target objects in the marked area and determine their respective measurement directions, and determine the number of pixels occupied by each target object in the respective measurement direction in the PCB scan image; and calculate the size of each target object in the requested measurement direction based on the currently set pixel unit size and the number of pixels occupied by each target object in the marked area.

It is also possible to define an area in the PCB design image to locate all design objects within the defined area, and then associate and map them to the PCB scan image to obtain target objects associated with each design object. Then, through the above-mentioned single target object measurement method, multiple target objects are measured one by one, and compared with the design (reference) size in batches, which can effectively improve the defect detection efficiency.

Furthermore, in a particular embodiment, during the scanning process of the AOI device, a counting step of the number of pixels of each object on the PCB in each measuring direction is automatically executed, so that after the AOI device completes the scan, the two-dimensional measurement result data of all objects on the PCB (in each measuring direction) can be immediately obtained.

Specifically, the number of pixels occupied by each scanned object on the circuit board in the PCB scan image in the requested measurement direction is counted in the following manner:

Locate the starting point of the target object in its measurement direction, with a count of 1;

Step to the next pixel block in the measuring direction. If the grayscale value difference between the current pixel block and the pixel block in the previous step exceeds the preset grayscale threshold, then stop counting and stop stepping. Otherwise, the count is incremented by 1.

Repeat the step of stepping to the next pixel block in the measuring direction until the grayscale value difference between the current pixel block and the pixel block in the previous step exceeds the preset grayscale threshold, and then use the current counting result as the number of pixels occupied by the target object in the PCB scan image in its measuring direction.

In one embodiment of the present invention, a 2D metrology measurement method for a printed circuit board is provided. As shown in FIG. 2 , the metrology measurement method includes:

Obtaining a PCB scan image obtained by scanning a target circuit board by an AOI device, and obtaining a pixel unit size currently set by the AOI device;

Select one or more target objects in the PCB scan image and determine the measurement direction thereof;

Determining the number of pixels occupied by the target object in the PCB scan image in the respective corresponding measurement directions;

According to the pixel unit size currently set for the AOI device and the number of pixels occupied by the target object in the requested measurement direction, the size of the target object in its measurement direction is calculated by multiplying the two.

One of the concepts of the present invention is to use an AOI line scan camera to scan a PCB circuit board, and then stitch the images obtained by the line scan to obtain an overall PCB scan image. The scan resolution given by the AOI device can be converted into a single pixel size, or the AOI device directly gives a single pixel size to perform two-dimensional metrology measurement directly in the PCB scan image, that is, the number of pixels "passed through" by the target object in the measurement direction multiplied by the side length of a single pixel is the length of the target object in the measurement direction. In this embodiment, the number of pixels occupied by a target object in the PCB scan image in its measurement direction is determined in the following manner:

Locate the starting point of the target object in its measurement direction, with a count of 1;

Step to the next pixel block in the measuring direction. If the grayscale value difference between the current pixel block and the pixel block in the previous step exceeds the preset grayscale threshold, then stop counting and stop stepping. Otherwise, the count is incremented by 1.

Repeat the step of stepping to the next pixel block in the measuring direction until the grayscale value difference between the current pixel block and the pixel block in the previous step exceeds the preset grayscale threshold, and then use the current counting result as the number of pixels occupied by the target object in the PCB scan image in its measuring direction.

In this embodiment, the printed circuit board 2D metrology measurement method further includes:

Mapping and associating the PCB scan image with the PCB design image in the design document of the target circuit board;

Determine a mapping object associated with the selected target object in the PCB design image;

Determining the size design information of the mapping object in the design document;

The difference between the calculated size of the target object in its metrological direction and the size design information of the mapped object in the design document is subtracted to obtain the metrological measurement result of the target object.

The printed circuit board 2D metrology measurement method embodiment and the above-mentioned PCB defect detection method embodiment are based on the same invention concept, and the printed circuit board 2D metrology measurement method embodiment and the PCB defect detection method embodiment are combined here.

In one embodiment of the present invention, a method for manufacturing a printed circuit board is provided. As shown in FIG. 4 , the method comprises:

Set various initial process parameters according to the design documents of the circuit board;

Producing a circuit board to be verified according to the initial process parameters;

Detecting the circuit board using the method described in the above PCB defect detection method embodiment;

If it is determined that the circuit board does not have defects, batch production is carried out according to current process parameters;

Otherwise, the process type of the object with defects is determined according to the PCB design document; the process parameters of the determined process type are corrected so that the size difference between the measured size of the target object of the circuit board manufactured by the corrected process and the size design information in the design document is reduced.

It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus. In the absence of further restrictions, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or apparatus including the element.

The above is only the specific implementation method of this application. It should be pointed out that for ordinary technical personnel in this technical field, they can make some improvements and embellishments without departing from the principles of this application. These improvements and embellishments should also be regarded as the protection scope of this application.

without

In order to more clearly explain the technical solutions in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Figure 1 is a schematic diagram of a PCB defect detection method based on 2D metrology provided by an exemplary embodiment of the present invention; Figure 2 is a schematic diagram of a printed circuit board 2D metrology measurement method provided by an exemplary embodiment of the present invention; Figure 3 is a schematic diagram of a metrology interface of a two-dimensional metrology software provided by an exemplary embodiment of the present invention; Figure 4 is a schematic diagram of a printed circuit board manufacturing method based on 2D metrology provided by an exemplary embodiment of the present invention.

Claims (9)

A PCB defect detection method, comprising: inputting a PCB design document of a circuit board to be detected into an AOI device, wherein the PCB design document includes the size design information of each object on the circuit board; scanning the circuit board to be detected by the AOI device to obtain a PCB scan image, and obtaining the pixel unit size currently set by the AOI device; responding to a trigger signal of a detection request for at least one target object, determining the number of pixels occupied by the target object in the PCB scan image in a requested measurement direction; calculating the size of the target object in the requested measurement direction by multiplying the pixel unit size currently set by the AOI device and the number of pixels occupied by the target object in the requested measurement direction; comparing the pixel unit size currently set by the AOI device and the number of pixels occupied by the target object in the requested measurement direction; and calculating the size of the target object in the requested measurement direction by multiplying the two. If the size difference between the calculated size in the requested measurement direction and the size design information of the target object in the PCB design document exceeds the preset difference threshold, it is determined that the target object of the circuit board has a defect; and the process type of the target object is determined according to the PCB design document; the process parameters are corrected for the determined process type so that the size difference between the measured size of the target object of the circuit board produced by the corrected process and its size design information in the PCB design document is reduced, including: if the measured size of the wire width of the solder wire on the circuit board to be tested is smaller than the corresponding size design information, the etching time process parameter is reduced; if the measured size of the wire width of the solder wire on the circuit board to be tested is larger than the corresponding size design information, the etching time process parameter is increased. The PCB defect detection method as described in claim 1, wherein the trigger signal of the detection request for a target object includes: Preliminarily inputting the PCB scan image and the corresponding PCB design image in the PCB design document into the two-dimensional measurement software for display; mapping and associating the PCB scan image with the PCB design image; selecting the target object on the display interface of the PCB scan image and determining the measurement direction; and determining the mapping object associated with the selected target object in the PCB design image. The PCB defect detection method as described in claim 1, wherein the trigger signal of the detection request for a target object includes: inputting the PCB scan image and the corresponding PCB design image in the PCB design document into the two-dimensional measurement software for display in advance; mapping and associating the PCB scan image with the PCB design image; selecting a mapping object associated with the target object mapping on the display interface of the PCB design image; and determining the target object associated with the selected mapping object in the PCB scan image, and determining the measurement direction. A PCB defect detection method as described in claim 1, wherein, in response to a trigger signal of a detection request for a defined area, all target objects in the defined area are located and their respective measurement directions are determined, and the number of pixels occupied by each target object in the respective measurement direction in the PCB scan image is determined; and the size of each target object in the requested measurement direction is calculated based on the currently set pixel unit size and the number of pixels occupied by each target object in the defined area. The PCB defect detection method as described in claim 1, wherein the target object is a straight line segment or a curved line segment, and the corresponding requested measurement direction is the line segment length extension direction or the line width direction; or, the target object is a polygon, and the corresponding requested measurement direction is the edge length direction; or, the target object is a circle, and the corresponding requested measurement direction is the radial direction. The PCB defect detection method as described in claim 1, wherein the PCB scan image is a grayscale image or a color image. A PCB defect detection method as described in any one of claim items 1 to 6, wherein, during the scanning process of the AOI device, the number of pixels occupied by each scanned object on the circuit board in the PCB scan image in the requested measurement direction is counted, until the scanning is completed, the number of pixels occupied by all objects on the circuit board in the PCB scan image in the requested measurement direction and/or the size of all objects in the requested measurement direction are obtained. A PCB defect detection method as described in claim 7, wherein the number of pixels occupied by each scanned object on the circuit board in the PCB scanned image in the requested measurement direction is counted in the following manner: the starting end point of the target object in its measurement direction is located, and the count is 1; stepping to the next pixel block in the measurement direction, if the grayscale value difference between the current pixel block and the pixel block in the previous step exceeds the preset grayscale threshold, then stop counting and stop stepping, otherwise the count is automatically incremented by 1; repeating the step of stepping to the next pixel block in the measurement direction until the grayscale value difference between the current pixel block and the pixel block in the previous step exceeds the preset grayscale threshold, and then taking the current counting result as the number of pixels occupied by the target object in the PCB scanned image in its measurement direction. A method for manufacturing a printed circuit board, comprising: setting various initial process parameters according to a design document of a circuit board; manufacturing a circuit board to be verified according to the initial process parameters; inspecting the circuit board using a PCB defect detection method as described in any one of claims 1 to 8; if it is determined that the circuit board does not have defects, mass production is carried out according to the current process parameters; otherwise, the process type of the object with defects is determined according to the design document of the circuit board; and the process parameters are corrected for the determined process type, so that the difference between the measured size of the target object of the circuit board manufactured by the corrected process and the size design information in the design document is reduced.

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