激光再流焊焊接速度对SOP器件焊点力学性能的影响

Effects of laser soldering speed on mechanical properties of SOP micro-joints

关键词:  激光再流焊  焊接速度  力学性能

Key words:  laser soldering  soldering speed  mechanical property

摘要:

分别采用半导体激光再流焊与红外再流焊方法钎焊SOP器件,研究了激光焊焊接速度对其焊点抗拉强度的影响,并对焊点断口形貌进行了分析。结果表明,在激光再流焊条件下,激光焊焊接速度对SOP器件焊点的抗拉强度有显著的影响,而Sn-Pb焊点的力学性能对焊接速度的敏感度低于Sn-Ag-Cu无铅焊点,且存在一个最佳焊接速度。通过SEM观察发现,焊接速度相对慢时,断口有浅显韧窝和微孔,焊点断裂类型为微孔聚合型断裂;速度过快时,断口有较多的韧窝群,并且局部区域还有台阶,焊点断裂类型为韧窝型断裂和解理型断裂;焊接速度适中时,断口韧窝大且深,焊点断裂类型为韧性断裂。

Abstract:

SOP(small outline package)devices were soldered by diode-laser soldering and IR reflow soldering method respectively and the tensile strengths of soldered joints were measured by Microjoints Tester(STR-1000), and the effects of laser soldering speed on mechanical properties of SOP micro-joints were studied and the characteristics of fracture microstructures of micro-joints were also analyzed by SEM.The results indicate that the tensile strength of soldered joints is influenced remarkably by laser soldering speed, and the mechanical properties of the joints soldered with Sn -Ag -Cu solder are more sensitive to soldering speed than that with Sn -Pb solder, and there is an optimal speed of laser soldering according to the best mechanical property.There are some micropores and shallow dimples when the speed is lower, which is called micropore aggregation fracture.There are plenty of dimples in the fracture and some sidesteps in the local zone of the fracture when the speed is higher, which the fracture includes dimple and cleavage fracture, and when the speed is moderate, there are lots of big and deep dimples in the fracture, which is the ductile fracture.