Laser bonded microjoints between titanium and polyimide for applications in medical implants

Area of Science:

• Biomaterials Engineering
• Medical Device Technology
• Laser Material Processing

Background:

• Hermetic sealing is critical for bio-encapsulation of medical and neural implants.
• Joining dissimilar biocompatible materials like titanium and polyimide presents significant challenges.

Purpose of the Study:

• To investigate laser processing conditions for creating reliable joints between titanium and polyimide.
• To characterize the mechanical properties and failure mechanisms of laser-fabricated microjoints.

Main Methods:

• Utilized near-infrared diode and fiber lasers for joining titanium and polyimide along transmission bonding lines (200-300 µm width).
• Employed laser powers of 2.2 W and 3.8 W.
• Conducted tensile loading tests on microjoints using a microtester.
• Performed finite element analysis (FEA) to model stress distribution and predict failure modes.

Main Results:

• Successfully established processing conditions for laser joining of titanium and polyimide.
• Determined joint strengths through tensile testing.
• FEA provided detailed stress distribution maps, elucidating failure mechanisms under tensile load.

Conclusions:

• Laser fabrication offers a viable method for creating microjoints between titanium and polyimide for bio-encapsulation.
• The study provides an initial framework for characterizing and optimizing laser-welded microjoints for medical implants.