Welding spot morphology defect statistical method based on X-ray CT

Abstract

The invention relates to a welding spot morphology defect statistical method based on X-ray CT. The welding spot morphology defect statistical method comprises the following steps that a to-be-tested circuit board conforming to test conditions is manufactured; performing X-ray CT scanning on the welding spot layer of the circuit board to be tested by using a high-precision computed tomography system; the obtained welding spot CT image slices are subjected to batch processing; and obtaining morphology data of all the welding spots and carrying out statistical analysis. The method relates to X-ray CT scanning of a circuit board, and processing and morphology analysis of a welding spot slice image by using software. Compared with other modes, the method has the advantages that more refined morphology statistical analysis can be performed on the morphology of the welding spot, and technical support is provided for subsequent stress load analysis and failure mode analysis of the welding spot.

Description

Technical Field

[0001] The invention relates to a method for counting solder joint morphology defects based on X-ray CT, belongs to the technical field of electronic packaging, and is used for counting the morphology defects of solder balls after packaging a flip-chip welding process. Background Art

[0002] There have been many failure accidents of microelectronic packaging under thermal load in the aerospace field. In the flip-chip soldering process of microelectronic packaging, void defects may occur in the solder joints, affecting the fatigue life and electrical connection characteristics of the package. The generation of voids is due to the evaporation of the flux during the flux reaction in the packaging welding process, and the generated gas may be trapped inside the solder joint, thereby generating unwanted pores. At the same time, due to factors such as gravity, temperature changes, and vibration, the surface shape of the solder joint is irregular. Due to the limitations of the packaging form, the internal solder joints are inaccessible to visible light, so a solder joint morphology measurement method is needed to perform a refined morphology statistical analysis of the solder joint morphology.

[0003] When X-rays pass through solder joints, their attenuation is related to parameters such as solder density, thickness and particle size. Using this characteristic, X-ray computed tomography (CT) performs ray projection measurements on solder joints at different angles on circuit boards, and reconstructs tomographic images to obtain three-dimensional digital images that reflect the internal structure of solder joints, thereby obtaining the surface shape and internal structure information of internal solder joints in a non-destructive way. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the above-mentioned deficiencies of the prior art, the present invention proposes a method for counting solder joint morphology defects based on X-ray CT, which involves X-ray CT scanning of a circuit board and the use of software to process and analyze the solder joint slice images. Compared with other methods, this method can perform a more refined morphology statistical analysis of the solder joint morphology, providing technical support for subsequent stress load analysis and failure mode analysis of the solder joint.

[0006] (II) Technical solution

[0007] A method for counting solder joint morphology defects based on X-ray CT comprises the following steps:

[0008] S1. Make a circuit board to be tested that meets the test conditions;

[0009] S2. Perform an X-ray CT scan of the solder joint layer of the circuit board to be tested using a high-precision computed tomography system;

[0010] S3. The obtained weld CT image slices are batch processed;

[0011] S4. Obtain all solder joint morphology data and perform statistical analysis.

[0012] In step S1, the diameter of the solder joint of the circuit board to be tested is 0.6 mm, and the side length of the circuit board is 10 mm.

[0013] In step S2, the high-precision computed tomography system is an industrial CT with an accuracy of 5 um.

[0014] In step S3, the batch processing adopts program operation and involves threshold segmentation.

[0015] In step S4, the statistical analysis obtains a frequency histogram of the solder joint equivalent diameter and solder joint morphology data, wherein the solder joint morphology data includes solder ball diameter, height, and sphericity.

[0016] The solder joint morphology data also includes the surface area and volume of the solder ball.

[0017] (III) Beneficial effects

[0018] Compared with the prior art, the solder joint morphology defect statistics method based on X-ray CT of the present invention has the following beneficial effects:

[0019] (1) Break through the measurement limitation of visible light inside the solder joint and obtain the real morphology data of the solder joint layer, making the subsequent morphology statistical analysis more reliable;

[0020] (2) Obtain detailed statistical data of solder joints, which can be used as a basis for evaluating the quality of solder joint packaging;

[0021] (3) Do not destroy the structure of the packaging structure itself and maintain the integrity of the sample. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Circuit board diagram that meets the test conditions

[0023] Figure 2 X-ray scanning slice image of solder joint

[0024] Figure 3 Frequency histogram of equivalent diameter of solder joints DETAILED DESCRIPTION

[0025] A method for counting solder joint morphology defects based on X-ray CT of the present invention comprises the following steps:

[0026] S1. Make a circuit board to be tested that meets the test conditions;

[0027] S2. Perform an X-ray CT scan of the solder joint layer of the circuit board to be tested using a high-precision computed tomography system;

[0028] S3. The obtained weld CT image slices are batch processed;

[0029] S4. Obtain all solder joint morphology data and perform statistical analysis.

[0030] See also Figure 1 In step S1, the diameter of the solder joint of the circuit board to be tested is 0.6 mm, and the side length of the circuit board is 10 mm.

[0031] The high-precision computed tomography system described in step S2 is an industrial CT with an accuracy of 5 um.

[0032] See also Figure 2 ,In step S3, the batch processing adopts program operation, involving threshold segmentation.

[0033] See also Figure 3 In step S4, the statistical analysis obtains the frequency histogram of the solder joint equivalent diameter and the solder joint morphology data, and the solder joint morphology data includes the solder ball diameter, height, and sphericity.

[0034] The solder joint morphology data also includes the surface area and volume of the solder ball.

[0035] The present invention proposes a solder joint morphology defect statistics method based on X-ray CT, which involves X-ray CT scanning of a circuit board and the use of software to process and analyze the solder joint slice images. This method can perform a more refined morphology statistical analysis of the solder joint morphology, providing technical support for subsequent stress load analysis and failure mode analysis of the solder joint.

Claims

1. A statistical method for solder joint morphology defects based on X-ray CT, characterized in that: The following steps are involved: S1. Make a circuit board to be tested that meets the test conditions; S2. Perform an X-ray CT scan of the solder joint layer of the circuit board to be tested using a high-precision computed tomography system; S3. The obtained weld CT image slices are batch processed; S4. Obtain all solder joint morphology data and perform statistical analysis.

2. The QFN package structure strain measurement method based on microscopic DIC according to claim 1, characterized in that: In step S1, the diameter of the solder joint of the circuit board to be tested is 0.6 mm, and the side length of the circuit board is 10 mm.

3. The QFN package structure strain measurement method based on microscopic DIC as claimed in claim 2, characterized in that: In step S2, the high-precision computed tomography system is an industrial CT with an accuracy of 5 um.

4. The QFN package structure strain measurement method based on microscopic DIC as claimed in claim 3, characterized in that: In step S3, the batch processing adopts program operation and involves threshold segmentation.

5. The QFN package structure strain measurement method based on microscopic DIC according to claim 4, characterized in that: In step S4, the statistical analysis obtains a frequency histogram of the solder joint equivalent diameter and solder joint morphology data, wherein the solder joint morphology data includes solder ball diameter, height, and sphericity.

6. The QFN package structure strain measurement method based on microscopic DIC according to claim 4, characterized in that: The solder joint morphology data also includes the surface area and volume of the solder ball.

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