A relatively new technique to the medical market segment to join multiple components to form a function assembly is laser welding. Through-Transmission Laser Welding (TTLW), is accomplished using "near-infrared" laser energy. 

The laser energy is passed through a "near-infrared" transmitting part and is absorbed at the surface of a second "near-infrared" absorbing part.  This is enabled by the use of "near-infrared" additives.  Energy sufficient to cause a temperature rise above the melting point of the polymer is supplied to the joint interface.  Heat, in combination with external clamping pressure, causes the two surfaces to weld at the joint interface.  Parameters such as laser power, laser beam width, and laser speed are used to optimize joint strength.

Desirable characteristics of the laser welding process:

• Excellent joint strength with Eastman™ copolyester resins
• Excellent welded joint aesthetics
• No flashes or particulate created by the welding process
• No chemical attack or "crazing" of Eastman™ copolyesters in combination with the Clearweld® fluid
• Very short weld cycle time
• No cure time requirement