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Lead-free component interconnection welding spot tin whisker touch risk assessment method

A technology for risk assessment and components, applied in the direction of design optimization/simulation, etc., can solve the problems of difficult extraction of tin whisker parameters, no model describing the growth of tin whiskers over time, and no clear evaluation method, etc., and achieves great application prospects.

Pending Publication Date: 2020-05-08
CHINA ACADEMY OF SPACE TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the parameters in the existing tin whisker growth models are not easy to extract, there is no model describing the change of tin whisker growth with time, and there is no clear evaluation method for the risk of tin whisker contact

Method used

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  • Lead-free component interconnection welding spot tin whisker touch risk assessment method
  • Lead-free component interconnection welding spot tin whisker touch risk assessment method
  • Lead-free component interconnection welding spot tin whisker touch risk assessment method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0093] Step 1: Conduct tin whisker growth stimulation test.

[0094] The test sample is a copper plate (red copper T2) with a thickness of 5μm pure tin (purity ≥99.0%), the test stress condition is 60℃, 95%RH, and the surface of the test sample is observed with a scanning electron microscope (SEM) every 10 days .

[0095] Step 2: Determination of characteristic parameters of tin whiskers.

[0096] After 20 days of the test, a large amount of tin whiskers grew, Figure 7 Schematic diagram of tin whiskers grown by scanning electron microscope (SEM).

[0097] According to the proposed measurement method of tin whisker growth length, growth density, and growth angle, use SEM to measure and record the growth length distribution of tin whiskers as shown in Table 2, the growth density distribution of tin whiskers is shown in Table 3, and the growth angle of tin whiskers The distribution is shown in Table 4.

[0098] Table 2 Growth length distribution of tin whiskers

[0099]

[0100]

[0101]...

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Abstract

The invention provides a lead-free component interconnection welding spot tin whisker touch risk assessment method. The method comprises the following steps that 1, performing a tin whisker growth excitation test; 2, measuring tin whisker characteristic parameters; 3, analyzing a tin whisker growth distribution rule and establishing a tin whisker growth characteristic model; and 4, evaluating thetin whisker touch risk of the lead-free component interconnection welding spot. According to the method, a lead-free component is used as a research object; the problem of tin whisker growth of lead-free component interconnection welding spots is solved. Carrying out a tin whisker growth test, measuring the tin whisker growth length, the tin whisker growth density and the tin whisker growth anglein combination with tin whisker growth characteristic parameters, carrying out statistical analysis on test data to obtain a growth distribution rule and a growth characteristic model of tin whiskers,and evaluating the touch risk of the tin whiskers of the lead-free component interconnection welding spots by utilizing a Monte Carlo analysis algorithm. According to the method, a reliable technicalbasis is provided for evaluating the tin whisker touch risk of the lead-free component interconnection welding spot.

Description

Technical field [0001] The invention belongs to the field of risk assessment of tin whisker touch in lead-free component interconnection solder joints, and relates to a method for assessing the risk of lead-free component interconnection solder joint tin whisker touch. Background technique [0002] For a long time, the solder used for the assembly of the components and the plating of the terminal is lead-tin solder (63Sn-37Pb). But lead is a toxic heavy metal, which is harmful to the human body and causes environmental pollution. Therefore, the lead-free regulations for electronic products in various countries have been issued one after another, and lead-free components have begun to gradually replace lead components. But compared with tin-lead materials, lead-free materials lack the inhibitory effect of lead, and tin whisker growth will occur. Conductive tin whiskers can cause equipment short-circuits, debris pollution, vacuum metal vapor arcs and other reliability problems, wh...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F30/20
Inventor 张伟李楠张海明吴照玺谷瀚天
Owner CHINA ACADEMY OF SPACE TECHNOLOGY
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