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A method for evaluating the reliability of lead-free solder joints

A lead-free solder joint reliability technology, applied in welding equipment, metal processing equipment, manufacturing tools, etc., can solve problems such as unsuitable lead-free solder joint reliability evaluation, reduce the difficulty of sample preparation, and achieve accurate statistics Effect

Active Publication Date: 2021-04-20
HARBIN INST OF TECH SHENZHEN GRADUATE SCHOOL
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Problems solved by technology

Therefore, the reliability evaluation method of traditional tin-lead solder joints is not applicable to the reliability evaluation of lead-free solder joints in principle

Method used

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  • A method for evaluating the reliability of lead-free solder joints

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Embodiment Construction

[0016] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0017] The structure of the traditional Pb-Sn solder joint is composed of β-Sn and the Pb-rich phase surrounding it. The structure is fine, and because the Pb-rich phase is soft, the mechanical properties of the entire solder can be considered to be isotropic. . After the solder joints are lead-free, the Sn content dominates, and the solder joints are mainly composed of Sn-based solder. After reflow, the solder joints are composed of β-Sn, Ag3Sn and Cu6Sn5, of which Ag3Sn and Cu6Sn5 are evenly distributed in the β- Near Sn, it plays the role of dispersion strengthening. In addition, it is observed that the number of grains inside the lead-free solder joint is far less than that of the traditional Pb-Sn solder joint, and sometimes there is even a single grain solder joint. There are few grains and surrounded by dispersion strengthening phase. T...

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Abstract

The present invention provides a method for evaluating the reliability of lead-free solder joints, which includes the following steps: S1. Using the non-destructive tomography mode of XRM, three-dimensional visual observation of the grain orientation of the solder joints is carried out to obtain the internal grain orientation difference of the solder joints Statistical data; S2. Whether the solder joint is in a recrystallized state is obtained from the statistical data of grain misorientation to evaluate the reliability of the solder joint for continued service. The method of the present invention is based on the exploration of the failure mechanism of the lead-free solder joint, and uses the XRM non-destructive tomography mode to observe the grain orientation of the solder joint in three dimensions, thereby evaluating and analyzing the reliability of the solder joint. The invention greatly reduces the difficulty of sample preparation in the traditional method of observing grain orientation, and realizes accurate statistics of grain orientation inside solder joints and reliability evaluation of lead-free solder joints.

Description

technical field [0001] The invention relates to the technical field of lead-free soldering process performance evaluation, in particular to a method for evaluating the reliability of lead-free solder joints. Background technique [0002] At present, the reliability testing methods of solder joints mainly include visual inspection, X-ray inspection, metallographic section, strength test, fatigue life, high temperature and high humidity, drop test, random vibration and other methods. [0003] Among them, the thermal fatigue life test based on temperature cycle uses the S-N curve to evaluate and predict the life of solder joints. In the JESD22-104-B standard, the experimental conditions are described as follows: [0004] Temperature: 0℃~100℃, -25℃~100℃, -40℃~125℃, -55℃~125℃, -55℃~100℃; [0005] High and low temperature residence time: stay for 10 minutes for leaded solder joints, and 10 to 30 minutes for lead-free solder joints; [0006] Temperature change rate: less than 20...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B23K31/12
CPCB23K31/12
Inventor 陈宏涛谢星驰
Owner HARBIN INST OF TECH SHENZHEN GRADUATE SCHOOL
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