High-power IR laser in SMT package

Abstract

ABSTRACT Laser dies in an optical power range of 1-3 Watts are wi dely assembled in popular TO- packages. TO-packages suffer from high thermal resistance and limited output power. Bad thermal contact between circuit boards and TO-devices can cause overheating of laser chips, significantly reducing the operating life time. We developed a compact high heat-load SMT package for an optical power up to 7 Watts in CW operation with good life time results. The new package for high power laser chips combines highly efficient heat dissipation with Surface-mount technology. A Direct-Bonded-Copper (DBC) substrate acts as a base plate for the laser chip and heat sink. The attached frame is used for electrical contacting and acts as beam reflector where the laser light is refl ected at a 45° mirror. In the application the DBC base plate of the SMT-Laser is directly soldered to a Metal-C ore-PCB by reflow soldering. The overall thermal resistance from laser chip to the botto m of a MC-PCB was measured as low as 2.5 K/W. The device placement process can be operated by modern high-speed mounting equipment. The direct link between device and MC-PCB allows CW laser operation up to 6-7 watts at wavelengths of 808nm to 940nm without facing any overheating symptom like thermal roll over. The device is suitable for CW and QCW operation. In pulsed operation short rise and fall times of <2ns have been demonstrated. New application fields like infrared illumination for sensing purposes in the automotive industry and 3D imaging systems could be opened by this new technology. Keywords: Laser diode, packaging, high-power, IR-Laser, SM T Technology, Infrared Illumination, QCW operation