Sn基钎料低温钎焊蓝宝石工艺及机理研究

发布时间：2018-06-09 03:25

本文选题：蓝宝石 + 超声钎焊　；参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：蓝宝石具有优异的高频特性与光学性能,且电子元器件的线膨胀系数非常相近,因此是如今应用最广泛的封装衬底和基板材料。在电子封装领域出于对温度的要求主要使用低温软钎焊技术对蓝宝石进行连接,但因其化学性质稳定而很难和钎料润湿。本文拟采用添加活性元素Ti和Al的Sn基活性钎料并引入超声作用改善润湿性,在大气环境下实现蓝宝石的有效连接,并研究其连接机理。首先使用添加活性元素Ti的SnAg基活性钎料Sn3.5Ag4Ti超声钎焊蓝宝石,试验结果表明,该钎料对蓝宝石的润湿性很好,直接超声钎焊和超声热浸后超声钎焊均可在蓝宝石间形成良好连接,超声热浸时间10s达到稳定强度33MPa,继续延长超声时间不影响接头强度。界面连接机理为超声作用下钎料中高活性的Ti向界面富集并分别和蓝宝石表面的Al_2O_3与空气中的O发生置换反应和沉积反应在界面形成厚薄不同且不均匀的Ti_2O_3沉积层。其次使用添加活性元素Al的SnAg基活性钎料Sn3.5Ag4Al超声钎焊蓝宝石,该钎料的润湿性相对较差,直接超声钎焊不能连接蓝宝石,通过超声热浸改善润湿性后才能在蓝宝石间形成良好连接。剪切强度随超声热浸时间的延长而提高,超声热浸100s时最高强度达到36MPa。界面连接机理为超声作用下钎料中的Al及Al的化合物溶解后向界面扩散并与O反应生成Al_2O_3,TEM结果证明,界面处Al_2O_3非晶层和Ag的富集是其界面强化因素。但上述两种钎料中活性元素Ti和Al都以化合物的形式存在而不易溶解,且这两者钎料中含有成本高的贵金属Ag。因此本文提出用成本较低的Sn9Zn2Al钎料,该钎料有Sn Zn Al的低熔点三元共晶相而更易溶解。使用Sn9Zn2Al钎料超声钎焊蓝宝石,试验证明直接超声钎焊和超声热浸后超声钎焊均可以实现蓝宝石的良好连接。随超声时间的延长,接头剪切强度分20s~50s快速上升和50s~2000s缓慢上升两个阶段,其界面连接机制和Sn3.5Ag4Al相似,界面处Al_2O_3非晶层和Zn的富集是其界面强化因素。采用含Zn量不同的钎料SnxZn2Al(x=9,25,45)直接超声钎焊蓝宝石,均实现了蓝宝石的良好连接,且强度随含Zn量的增加而提高。使用Sn45Zn2Al时所得接头强度最高可达32MPa。通过增加钎料含Zn量实现了蓝宝石短时间较高强度的连接。
[Abstract]:Sapphire has excellent high frequency characteristics and optical properties, and the linear expansion coefficient of electronic components is very similar, so it is the most widely used packaging substrate and substrate materials. In the field of electronic packaging, the low temperature soldering technology is mainly used to connect sapphire due to the requirement of temperature, but it is difficult to wetting the solder because of its stable chemical properties. In this paper, Sn-based active solders with active elements Ti and Al are introduced to improve wettability, to realize the effective connection of sapphire in atmosphere, and to study the bonding mechanism of sapphire. Sn-Ag based active solder Sn3.5Ag4Ti was first used for ultrasonic brazing of sapphire. The experimental results show that the solder has good wettability to sapphire. Direct ultrasonic brazing and ultrasonic hot dip ultrasonic brazing can form a good connection between sapphire, and the ultrasonic hot dip time can reach a steady strength of 33MPa, and the extension of ultrasonic time does not affect the joint strength. The interface bonding mechanism is that the highly active Ti in the solder is enriched to the interface under the action of ultrasound and replaced with Al _ S _ 2O _ 3 on the sapphire surface and deposited with O in air to form a thin and uneven Ti _ 2O _ 3 deposit layer at the interface. Secondly, the Sn-Ag based active solder Sn3.5Ag4Al was used to weld sapphire. The wettability of the filler metal was relatively poor, and direct ultrasonic brazing could not connect sapphire. The wettability of sapphire can be improved by ultrasonic hot dip before a good connection between sapphire can be formed. The shear strength increases with the prolongation of ultrasonic hot dip time, and the maximum strength of ultrasonic hot dip reaches 36 MPA at 100 s. The interface bonding mechanism is that the Al and Al compounds in the filler metal dissolves and diffuses back to the interface and reacts with O to form Al _ 2O _ 3C _ T. The results of TEM show that the enrichment of Al _ 2O _ 3 amorphous layer and Ag at the interface is the main factor for the interface strengthening of Al _ 2O _ 3 and Al _ 2O _ 3. However, the active elements Ti and Al in the above two brazing alloys exist in the form of compounds and are insoluble, and the two solders contain high cost precious metal Ag. Therefore, a low cost Sn9Zn2Al solder is proposed, which has the low melting point ternary eutectic phase of Sn Zn Al and is easier to dissolve. Using Sn9Zn2Al solder for ultrasonic brazing sapphire, it is proved that both direct ultrasonic brazing and ultrasonic hot dip ultrasonic brazing can realize the good connection of sapphire. With the extension of ultrasonic time, the shear strength of the joint increases rapidly in 20s~50s and 50s~2000s slowly, and the interface bonding mechanism is similar to that of Sn3.5Ag4Al, and the enrichment of Al2O3 amorphous layer and Zn at the interface is the factor of interface strengthening. Direct ultrasonic brazing of sapphire with different Zn content of SnxZn _ 2AlN _ (9) O _ (9) (25 ~ (45) has realized good connection of sapphire, and the strength of sapphire is increased with the increase of Zn content. The maximum strength of the joints obtained with Sn45Zn2Al is up to 32MPa. The connection of sapphire with high strength in short time was realized by increasing Zn content of solder.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN05

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