發(fā)布時間：2018-10-23 14:57

【摘要】：隨著現(xiàn)代工業(yè)的迅速發(fā)展,Micro-USB電連接器已經(jīng)成為了人們生活中不可或缺的電子產(chǎn)品,對Micro-USB電連接器的使用壽命也隨之提上了議程。焊點是連接Micro-USB電連接器電氣和機(jī)械特性的橋梁,一旦焊點失效將直接致使其整體失效,因此對電連接器焊點的壽命預(yù)測是很有意義的。本文通過在溫度(-55℃-+125℃)周期性循環(huán)變化作用下,分析焊點的失效模式和失效機(jī)理,介紹了無鉛焊點的熱疲勞壽命。焊點采用的是Sn3.5Ag0.75Cu合金材料,其熔點溫度為217℃左右。當(dāng)循環(huán)溫度達(dá)到熔點的0.5時,焊點將會產(chǎn)生蠕變和應(yīng)力松弛,即能有效預(yù)測焊點在極限工作條件下的使用壽命。本文對Micro-USB電連接器焊點在周期性溫度變化條件下的壽命預(yù)測,主要工作內(nèi)容有:采用三維建模軟件Pro/E建立Micro-USB電連接器實體模型,主要包括Micro-USB電連接器主體、金屬Pin、導(dǎo)線線芯和SnAgCu無鉛焊點四個部分,并去除對分析結(jié)果影響不大的尖角部分,然后將其導(dǎo)入到有限元分析軟件ANSYS中進(jìn)行熱疲勞壽命分析;采用ANAND統(tǒng)一性本構(gòu)方程模型描述焊點在循環(huán)溫度載荷作用下的力學(xué)行為;采用參數(shù)化語言APDL命令設(shè)計了循環(huán)溫度載荷,并通過模擬理論分析計算焊點應(yīng)力應(yīng)變分布和變化情況。由于材料之間的熱膨脹系數(shù)不匹配,在低溫開始時刻焊點應(yīng)力應(yīng)變最大,高低溫保溫期間應(yīng)力應(yīng)變出現(xiàn)下降,在升溫和降溫期間應(yīng)力應(yīng)變變化最大。由此可見焊點萌生裂紋將在升溫或降溫期間,最終只是焊點失效;運(yùn)用基于塑性應(yīng)變的Coffin-Manson經(jīng)驗公式計算出焊點在熱循環(huán)溫度作用下的熱疲勞壽命。最終結(jié)果表明Micro-USB電連接器焊點在溫度周期性循環(huán)溫度作用下,最大應(yīng)力應(yīng)變發(fā)生在焊點與金屬Pin接觸的底部,并且中間焊點最為突出,由此可見,焊點裂紋萌生將從這里開始。計算結(jié)果表示焊點的壽命為1146次,印證了Micro-USB電連接器質(zhì)量的可靠性。
[Abstract]:With the rapid development of modern industry, Micro-USB electrical connectors have become an indispensable electronic product in people's lives, and the service life of Micro-USB electrical connectors has also been put on the agenda. The solder joint is the bridge connecting the electrical and mechanical characteristics of the Micro-USB electrical connector. Once the solder joint fails, it will lead to the whole failure directly, so it is very meaningful to predict the life of the electric connector solder joint. In this paper, the failure mode and failure mechanism of solder joints are analyzed under the cyclic variation of temperature (-55 鈩，

本文編號：2289580