A BGA detection method based on X-ray imaging

Abstract

The invention provides a BGA detection method based on X-ray imaging, comprising the following steps: for a sample, selecting a standard good product image as a template; obtaining a BGA sphere area of ​​the template by gray value area segmentation; treating the BGA sphere area as a whole, generating a shape template to realize array positioning of the BGA image to be tested; covering the template on the BGA image to be tested by matching; measuring BGA spheres one by one, comparing the key parameters of the BGA image to be tested with the template, and obtaining abnormal BGA points; drawing a BGA measurement result diagram; solving the problems that the traditional detection method is time-consuming, inefficient, inflexible, and can only determine the position information of the BGA but cannot obtain its gray information and related statistical data, and establishing a model is efficient and flexible, only one good sample picture is needed to complete the collection of all relevant information, and the method is applicable to BGA balls of various arrangements and is not limited by external conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of X-ray imaging detection, and in particular to a BGA detection method based on X-ray imaging. Background Art

[0002] In today's information age, with the rapid development of the electronics industry, products such as computers and mobile phones are becoming increasingly popular. People have more and more functional requirements for electronic products, and their performance requirements are getting stronger and stronger, while the volume requirements are getting smaller and smaller, and the weight requirements are getting lighter and lighter. This has prompted electronic products to develop in the direction of multi-function, high performance, miniaturization, and lightness. To achieve this goal, the characteristic size of IC chips must become smaller and smaller, and the complexity continues to increase. As a result, the number of I / Os in the circuit will increase, and the I / O density of the package will continue to increase. In order to meet this development requirement, some advanced high-density packaging technologies have emerged, and BGA (Ball Grid Array) packaging technology is one of them.

[0003] X-ray imaging can clearly observe the size and shape of the solder balls in the BGA, so it is very effective to use X-ray imaging technology to detect the welding status of the BGA. However, although the BGAs of different products are arranged in arrays, their arrangement rules are very different. The traditional detection method requires the design of an ROI detection frame for each BGA ball point. The design of the ROI detection frame is cumbersome, and the ROI needs to be re-edited when changing different products, resulting in low detection efficiency. To solve the above problems, the following two measures are generally taken: 1) Create a sufficiently large BGA array library. The same template can be selected from the library for testing BGA images, and the template is used for editing, positioning and subsequent testing. However, this measure must ensure that the BGA array library is large enough, otherwise the problem of different editing points cannot be solved. However, when the BGA array library is large enough, it will be time-consuming to find the template; 2) Import the BGA array standard template through the CAD file, which makes the model establishment too dependent on the CAD file and not flexible enough; and both measures can only determine the location information of the BGA, and cannot obtain its grayscale information and related statistical data. Summary of the invention

[0004] The present invention discloses a BGA detection method based on X-ray imaging, which solves the problems that the traditional detection method is time-consuming, inefficient, inflexible, and can only determine the position information of BGA but cannot obtain its grayscale information and related statistical data. The model is efficient and flexible to establish, and only one good sample picture is needed to complete the collection of all relevant information. The method is applicable to BGA balls of various arrangements and is not restricted by external conditions.

[0005] To achieve the above object, the technical solution of the present invention is specifically implemented as follows:

[0006] The present invention discloses a BGA detection method based on X-ray imaging, comprising the following steps:

[0007] S1: For a sample, select a standard good product image as a template;

[0008] S2: obtaining the BGA ball area of ​​the template by gray value area segmentation;

[0009] S3: treating the BGA sphere area as a whole and generating a shape template to achieve array positioning of the BGA image to be tested;

[0010] S4: Overlaying the template on the BGA image to be tested by matching;

[0011] S5: measuring the BGA spheres one by one, comparing the key parameters of the measured BGA image with the template, and obtaining abnormal BGA points;

[0012] S6: Draw a BGA measurement result graph.

[0013] Furthermore, step S3 also includes:

[0014] Record the diameters of all BGA balls and calculate the standard diameter, maximum diameter and minimum diameter;

[0015] Record the adjacent spacing of all BGA balls, and calculate the standard spacing, maximum spacing, and minimum spacing;

[0016] The grayscale distribution of all BGA balls on the template is recorded, and the grayscale distribution average value, grayscale maximum value and grayscale minimum value are calculated.

[0017] Furthermore, the step S5 includes:

[0018] The spherical area of ​​the tested BGA image and the spherical area of ​​the matched template image are intersected. If the area obtained by the intersection is less than 0.2 times the standard area of ​​the BGA, it is judged that the solder ball is missing.

[0019] Furthermore, the step S5 includes:

[0020] Draw a circumscribed circle and an inner circle for the spherical area of ​​the measured BGA image, and obtain the diameter of the circumscribed circle and the inner circle diameter. Compare the circumscribed circle diameter and the inner circle diameter with the BGA standard diameter. If the diameter exceeds the allowable error data range, it is judged that the solder ball is too small or too large.

[0021] Furthermore, the step S5 includes:

[0022] A test circle is made with the center of any solder ball in the spherical area of ​​the tested BGA image as the center and the BGA standard spacing as the radius. If the centers of the surrounding solder balls are not on the test circle, it is judged that the solder ball spacing is abnormal.

[0023] Furthermore, the step S5 includes:

[0024] A test circle is made with the center of any solder ball in the spherical area of ​​the tested BGA image as the center and a diameter smaller than the standard diameter of the BGA as the diameter. If the spherical contour of any solder ball in the spherical area of ​​the tested BGA image intersects with the test circle, it is judged as solder ball damage.

[0025] Furthermore, the step S5 includes:

[0026] A test circle is made with the center of any solder ball in the spherical area of ​​the tested BGA image as the center and a value greater than the standard diameter of the BGA as the diameter. If the spherical contour of any solder ball in the spherical area of ​​the tested BGA image intersects with the test circle, it is judged as solder ball overflow.

[0027] Beneficial technical effects:

[0028] The invention discloses a BGA detection method based on X-ray imaging, comprising the following steps: S1: for a sample, selecting a standard good product image as a template; S2: obtaining the BGA sphere area of ​​the template by gray value area segmentation; S3: treating the BGA sphere area as a whole, generating a shape template to realize array positioning of the BGA image to be tested; S4: covering the template on the BGA image to be tested by matching; S5: measuring BGA spheres one by one, comparing the key parameters of the BGA image to be tested with the template, and obtaining abnormal BGA points; S6: drawing a BGA measurement result diagram; the problem that the traditional detection method is time-consuming, inefficient, inflexible, and can only determine the position information of the BGA but cannot obtain its gray information and related statistical data is solved, the model is efficient and flexible to establish, only one good sample picture is needed to complete the collection of all relevant information, and it is applicable to BGA balls of various arrangements and is not restricted by external conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solution of the present invention, the drawings required for describing the embodiments are briefly introduced below.

[0030] Figure 1 A flowchart of the steps of a BGA detection method based on X-ray imaging according to the present invention;

[0031] Figure 2 BGA imaging under X-ray selected for Example 1;

[0032] Figure 3 It is a schematic diagram of the BGA ball area of ​​Example 1;

[0033] Figure 4 A schematic diagram of a BGA image under test in an embodiment;

[0034] Figure 5 It is a schematic diagram of the template of the first embodiment being overlaid on the image of the BGA to be tested through matching;

[0035] Figure 6 Schematic diagram of missing solder balls;

[0036] Figure 7 Schematic diagram of solder balls being too small / too large;

[0037] Figure 8 Schematic diagram of abnormal solder ball spacing;

[0038] Fig. 9 Schematic diagram of solder ball damage / overflow;

[0039] Fig.10 This is a BGA measurement result diagram of Example 1;

[0040] Fig.11 A schematic diagram of the BGA ball area on the template of Example 2;

[0041] Fig.12 This is a schematic diagram of the BGA ball area under test in Example 2;

[0042] Fig.13 The template matching of the second embodiment is overlaid on the image of the BGA to be tested;

[0043] Fig.14 This is a diagram of the calculation results of Example 2;

[0044] Fig.15 This is the BGA measurement result diagram. DETAILED DESCRIPTION

[0045] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0046] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0047] The present invention discloses a BGA detection method based on X-ray imaging, see Figure 1 , specifically including the following steps:

[0048] Embodiment 1:

[0049] S1: For a sample, select a standard good image as a template, see Figure 2 ;

[0050] S2: obtaining the BGA ball area of ​​the template by gray value area segmentation;

[0051] Specifically, through the learning mode of the algorithm, the BGA ball area is obtained by gray value area segmentation, see Figure 3 ;

[0052] S3: treating the BGA sphere area as a whole and generating a shape template to achieve array positioning of the BGA image to be tested;

[0053] Specifically, Figure 3 The white dots in the image are taken as a whole, and a shape template is generated using the template matching tool to act on the BGA array positioning during the test. At the same time, the following data are recorded

[0054] Record the diameters of all BGA balls and calculate the standard diameter, maximum diameter and minimum diameter;

[0055] Record the adjacent spacing of all BGA balls, and calculate the standard spacing, maximum spacing, and minimum spacing;

[0056] The grayscale distribution of all BGA balls on the template is recorded, and the grayscale distribution average value, grayscale maximum value and grayscale minimum value are calculated.

[0057] S4: Overlaying the template on the BGA image to be tested by matching;

[0058] Specifically, call the algorithm's measurement mode, use the shape template matching tool, and overlay the template on the BGA image to be measured by matching, see Figure 4-Figure 5 ;

[0059] S5: Measure the BGA spheres one by one, compare the key parameters of the measured BGA image with the template, and obtain abnormal BGA points.

[0060] Specifically, the more common inspection items for BGA inspection include but are not limited to missing solder balls, solder balls that are too small / too large, abnormal solder ball spacing, solder ball damage, and solder ball overflow.

[0061] The method to detect missing solder balls is:

[0062] The spherical area of ​​the tested BGA image and the spherical area of ​​the matched template image are intersected. If the area obtained by the intersection is less than 0.2 times the standard area of ​​the BGA, it is judged that the solder ball is missing. See Figure 6 ;

[0063] The method to detect solder balls that are too small / too large is:

[0064] Draw a circumscribed circle and an inner circle for the spherical area of ​​the measured BGA image, and obtain the diameter of the circumscribed circle and the inner circle diameter. Compare the circumscribed circle diameter and the inner circle diameter with the BGA standard diameter. If the diameter exceeds the allowable error data range, it is judged that the solder ball is too small or too large. See Figure 7 ;

[0065] The method to detect abnormal solder ball spacing is:

[0066] Take the center of any solder ball in the spherical area of ​​the tested BGA image as the center of the circle and the BGA standard spacing as the radius to make a test circle. If the center of the surrounding solder balls is not on the test circle, it is judged that the solder ball spacing is abnormal. Figure 8 ;

[0067] The method to detect solder ball damage is:

[0068] Take the center of any solder ball in the spherical area of ​​the tested BGA image as the center of the circle and the value smaller than the standard diameter of BGA as the diameter to make a test circle. If the spherical outline of any solder ball in the spherical area of ​​the tested BGA image intersects with the test circle, it is judged that the solder ball is damaged. See Fig. 9 ;

[0069] The method to detect solder ball overflow is:

[0070] Take the center of any solder ball in the spherical area of ​​the tested BGA image as the center of the circle and the value greater than the standard diameter of the BGA as the diameter to make a test circle. If the spherical outline of any solder ball in the spherical area of ​​the tested BGA image intersects with the test circle, it is judged as solder ball overflow. See Fig. 9 .

[0071] S6: Draw the BGA measurement result diagram to complete the measurement.

[0072] Specifically, the BGA measurement result diagram of the first embodiment is as follows: Fig.10 shown.

[0073] Embodiment 2:

[0074] S1: This embodiment selects Fig.11 is the template image;

[0075] S2: Obtain the BGA ball area of ​​the template by gray value area segmentation, see Fig.12 ;

[0076] S3: treating the BGA sphere area as a whole and generating a shape template to achieve array positioning of the BGA image to be tested;

[0077] The image of the BGA under test under X-ray is as follows: Fig.13 ;

[0078] S4: Overlay the template on the BGA image to be tested by matching, that is, Fig.12 Covered in Fig.13 Above, see Fig.14 ;

[0079] S5: Measure BGA balls one by one, compare the key parameters of the measured BGA image with the template, and obtain abnormal BGA points, that is, judge whether the solder ball is missing, the solder ball is too small / too large, the solder ball spacing is abnormal, the solder ball is damaged, and the solder ball overflows;

[0080] S6: Draw the BGA measurement result diagram to complete the measurement, see Fig.15 .

[0081] The present invention discloses a BGA detection method based on X-ray imaging, which can complete the collection of all relevant information with only one good sample picture of the sample, and is flexible and efficient; and the method can be adapted to various arrangements of BGA solder balls, is not limited by external conditions, and has wide applicability.

[0082] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0083] The above embodiments are only descriptions of the preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary engineering and technical personnel in the field should fall within the protection scope determined by the claims of the present invention.

Claims

1. A BGA detection method based on X-ray imaging, characterized in that: The following steps are involved: S1: For a sample, select a standard good product image as a template; S2: obtaining the BGA ball area of ​​the template by gray value area segmentation; S3: treating the BGA sphere area as a whole and generating a shape template to achieve array positioning of the BGA image to be tested; S4: Overlaying the template on the BGA image to be tested by matching; S5: measuring the BGA spheres one by one, comparing the key parameters of the measured BGA image with the template, and obtaining abnormal BGA points; S6: Draw the BGA measurement result diagram; The step S3 also includes: Record the diameters of all BGA balls and calculate the standard diameter, maximum diameter and minimum diameter; Record the adjacent spacing of all BGA balls, and calculate the standard spacing, maximum spacing, and minimum spacing; Record the grayscale distribution of all BGA balls on the template, and calculate the grayscale distribution average, grayscale maximum, and grayscale minimum; The step S5 includes: The spherical area of ​​the tested BGA image and the spherical area of ​​the matched template image are intersected. If the area obtained by the intersection is less than 0.2 times the standard area of ​​the BGA, it is judged that the solder ball is missing; The step S5 includes: Draw a circumscribed circle and an inner circle on the spherical area of ​​the BGA image to be tested, and obtain the diameter of the circumscribed circle and the inner circle diameter. Compare the circumscribed circle diameter and the inner circle diameter with the BGA standard diameter. If the diameter exceeds the allowable error data range, it is judged that the solder ball is too small or too large. The step S5 includes: A test circle is made with the center of any solder ball in the spherical area of ​​the tested BGA image as the center and the BGA standard spacing as the radius. If the center of the surrounding solder balls is not on the test circle, it is judged that the solder ball spacing is abnormal. The step S5 includes: A test circle is made with the center of any solder ball in the spherical area of ​​the tested BGA image as the center and a value smaller than the standard diameter of the BGA as the diameter. If the spherical contour of any solder ball in the spherical area of ​​the tested BGA image intersects with the test circle, it is judged as solder ball damage. The step S5 includes: A test circle is made with the center of any solder ball in the spherical area of ​​the tested BGA image as the center and a value greater than the standard diameter of the BGA as the diameter. If the spherical contour of any solder ball in the spherical area of ​​the tested BGA image intersects with the test circle, it is judged as solder ball overflow.

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