航空传感元件振镜激光钎焊界面组织及连接机理

Interface microstructure and formation mechanism of oscillating laser brazed joints for aerial sensing elements

航空传感元件作为航空电子传感系统的核心零部件,在使用过程中常常需要将其引脚与导线进行连接。为了进一步改善产品的稳定与可靠性,探索性的提出使用振镜激光钎焊技术实现铂电阻器引线银丝与多股铜线的连接。当激光器处于连续CW模式和离焦量+10 mm的情况下,通过调整工艺,激光功率与激光作用时间在一定适配范围内,能够避免接头中产生填隙不良和过度溶蚀现象,获得可靠无缺陷接头。接头中界面组织主要由Cu-Ni固溶体、Cu-Zn相、Ag基固溶体及典型的Ag-Cu共晶组织构成。热力学计算结果表明:在界面处中Cu、Zn原子在化学势驱动下相互扩散,Cu-Zn相具有更大的析出驱动力。Ag原子从银丝向铜线一侧扩散,在富Ag区形成典型Ag-Cu共晶组织。

The sensing element is the core component of the avionics sensing system,and the pin of the element is often needed to be welded to wires when in use.To further improve the stability and reliability of the product,the oscillating laser brazing technology is proposed to be used to realize the welding of the lead silver wire of platinum resistor and the multi-stranded copper wire.Under the condition that the laser CW continuous mode and the defocus distance of+10 mm remain unchanged,the laser power and scanning time could be adjusted within a certain range of adaptation by adjusting the process,which could avoid poor gap filling and excessive corrosion in the joint and finally obtain a reliable and defect-free joint.The interface structure mainly consisted of Cu-Ni solid solution,Cu-Zn phase,Ag-based solid solution,and typical Ag-Cu eutectic structure.The thermodynamic calculation results show that Cu and Zn atoms diffused mutually under the drive of chemical potential at the interface,and the Cu-Zn phase had a greater driving force for precipitation.Ag atoms diffused from the silver wire to the side of the copper wire,forming the typical Ag-Cu eutectic structure in the Ag-rich region.