Crossed-Wire Laser Microwelding of Pt-10 Pct Ir to 316 LVM Stainless Steel: Part II. Effect of Orientation on Joining Mechanism

Abstract

With the increasing complexity of medical devices and with efforts to reduce manufacturing costs, challenges arise in joining dissimilar materials. In this study, the laser weldability of dissimilar joints between Pt-10 pct Ir and 316 low-carbon vacuum melted (LVM) stainless steel (SS) crossed wires was investigated by characterizing the weld geometry, joint strength, morphology of weld cross sections, and differences in joining behavior, depending on which material is subject to the incident laser beam. With the Pt-Ir alloy on top, a significant amount of porosity was observed on the surface of the welds as well as throughout the weld cross sections. This unique form of porosity is believed to be a result of preferential vaporization of 316 LVM SS alloying elements that become mixed with the molten Pt-10 pct Ir during welding. The joining mechanism documented in micrographs of cross-sectioned welds was found to transition from laser brazing to fusion welding. It is inferred that the orientation of the two dissimilar metals (i.e., which material is subject to the incident laser beam) plays an important role in weld quality of crossed-wire laser welds.

A Connection Method between Ultrahard PtW8 Wire and a Au Thick Film Based on Parallel-Gap Resistance Microwelding

“…However, the physical properties of the materials studied are not much different and the joint formation during the bonding process is not clear. In research on the resistance microwelding of crossed Pt-Ir alloy wire and 316 LVM stainless steel wires, Huang et al showed that increasing the wetting of molten metal on the surface of the joint can significantly improve the performance of the joint [ 17 , 18 , 19 ].…”

Femtosecond laser-induced microwelding of silver and copper

“…Lasers are excellent devices for welding because of their ability to introduce a high power density into a small zone [1]. Recently, with the development of miniaturization, laser welding has been applied in the production of microelectronic and biomedical devices [2][3][4][5]. In the microelectronics industry, electronics packaging is of major importance and wire bonding represents more than 90% of the packaging market due to its cost-effectiveness and flexibility [6].…”

Resistance microwelding of crossed Pt–10Ir and 316 LVM stainless steel wires

“…1,8,10 Recently, the LMW process has been shown as a potential candidate for crossed wire welding of dissimilar materials. 7,11,12 However, many difficulties in the LMW of dissimilar materials were also found to exist. For example, the laser welds between dissimilar Pt and Ti alloys were shown to be susceptible to cracking due to the generation of brittle Ti 3 Pt phase, 7 and porosity can also be a problem when laser welding dissimilar materials such as 316 LVM SS to Pt-Ir alloy.…”

“…For example, the laser welds between dissimilar Pt and Ti alloys were shown to be susceptible to cracking due to the generation of brittle Ti 3 Pt phase, 7 and porosity can also be a problem when laser welding dissimilar materials such as 316 LVM SS to Pt-Ir alloy. 12 In addition, the laser welding process does not provide the self-fixturing advantage of the RMW process. 1 RMW is widely used in medical industries since it is an economical process that offers excellent reliability and productivity at substantially lower capital costs.…”

“… 11 7,11,12 However, many difficulties in the LMW of dissimilar materials were also found to exist. For example, the laser welds between dissimilar Pt and Ti alloys were shown to be susceptible to cracking due to the generation of brittle Ti 3 Pt phase,7 and porosity can also be a problem when laser welding dissimilar materials such as 316 LVM SS to Pt–Ir alloy 12. In addition, the laser welding process does not provide the self-fixturing advantage of the RMW process 1…”