焊球的形成机理及去除方式研究
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摘要
焊球是构成焊膏的合金焊粉在烧焊时形成的可移动的金属颗粒物,粒径与焊粉相当,会对电路的可靠性造成不利影响,更会直接造成混合集成电路颗粒碰撞噪声检测(PIND)失效。依照IPC-TM-650测试方法手册2. 4. 43条给出的焊球测试的试验方法和测试标准,通过对比焊粉尺寸、焊膏是否含铅、焊膏印刷后静置时间及烧焊过程中是否通氮气对焊球产生的不同影响,阐述和论证了焊球形成的机理是焊膏吸湿和氧化,并指出在工艺生产中焊膏印刷或喷印时容易造成焊球生成的环节。焊球产生后会包裹在助焊剂中,但不会随着助焊剂的清洗而完全消除,会因静电原因继续吸附在基板上,待静电得到释放后,可采用高压氮气枪吹洗的方式有效去除。
Solder balls are mobile metal particles formed by the metal powder of solder paste during the welding. The particle size of solder balls is comparable to that of the solder powder. It has an adverse impact on the reliability of the circuit,directly leading to the failure of hybrid integrated circuit PIND( particle impact noise detection. The test methods and standards for the solder ball in the IPC-TM-650 manual No.2.4. 43 were used in this work. We demonstrates that the formation of solder ball is due to moisture absorption and oxidation of the solder paste. Here comparison was made for the effects caused by four factors,including the size of the solder powder,the lead composition of solder paste( both for lead and lead-free),the standing time after the solder paste printing,and the usage of nitrogen gas during the reflow process. In this work,the factors that cause solder ball formation were studied for both solder paste printing and jet printing. Solder ball will be contained in the flux after welding,and would not be completely removed during the flux removal. It is adsorbed on the substrate due to static electricity. It can be removed by high pressure nitrogen when static electricity is released.
Solder balls are mobile metal particles formed by the metal powder of solder paste during the welding. The particle size of solder balls is comparable to that of the solder powder. It has an adverse impact on the reliability of the circuit,directly leading to the failure of hybrid integrated circuit PIND( particle impact noise detection. The test methods and standards for the solder ball in the IPC-TM-650 manual No.2.4. 43 were used in this work. We demonstrates that the formation of solder ball is due to moisture absorption and oxidation of the solder paste. Here comparison was made for the effects caused by four factors,including the size of the solder powder,the lead composition of solder paste( both for lead and lead-free),the standing time after the solder paste printing,and the usage of nitrogen gas during the reflow process. In this work,the factors that cause solder ball formation were studied for both solder paste printing and jet printing. Solder ball will be contained in the flux after welding,and would not be completely removed during the flux removal. It is adsorbed on the substrate due to static electricity. It can be removed by high pressure nitrogen when static electricity is released.
引文
[1]罗雯,魏建中,阳辉,等.电子元器件可靠性试验工程[M].北京:电子工业出版社,2005.
[2]史建卫,宋耀宗.回流焊工艺中常见缺陷及其防止措施[J],电子工艺技术,2011,32(1):58-61.
[3]PRASAD R P.表面安装技术原理和实践[M].李春发,等译.第一版.北京:科学出版社,1994:188-189.
[4]VINCENT J H.Lead-free solders for electronic assembly[J].Gec J Res,1994,11(2):76-89.
[5]NURMI S,SUNDELIN J,RISTOLAINEN E,et al.The effect of solder paste composition on the reliability of SnAgCu joints[J].M icroelectron Reliab,2004,44:485-494.
[6]RETTENMAYR M,LAMBRACHT P,KEMPF B,et al.High melting Pb-free solder alloys for die-attach applications[J].Adv Eng M ater,2005,7(10):965-969.
[7]刘晓红,常青松.混合集成电路内部多余物的控制研究[J].半导体技术,2008,33(7):575-577.
[2]史建卫,宋耀宗.回流焊工艺中常见缺陷及其防止措施[J],电子工艺技术,2011,32(1):58-61.
[3]PRASAD R P.表面安装技术原理和实践[M].李春发,等译.第一版.北京:科学出版社,1994:188-189.
[4]VINCENT J H.Lead-free solders for electronic assembly[J].Gec J Res,1994,11(2):76-89.
[5]NURMI S,SUNDELIN J,RISTOLAINEN E,et al.The effect of solder paste composition on the reliability of SnAgCu joints[J].M icroelectron Reliab,2004,44:485-494.
[6]RETTENMAYR M,LAMBRACHT P,KEMPF B,et al.High melting Pb-free solder alloys for die-attach applications[J].Adv Eng M ater,2005,7(10):965-969.
[7]刘晓红,常青松.混合集成电路内部多余物的控制研究[J].半导体技术,2008,33(7):575-577.