Tungsten Copper Spacers for Semiconductor Lasers
- Flatness: 0.3 μm/mm.
- Edge radius better than 15 μm.
- Dimensional tolerances: ±10 μm.
- Surface roughness: as low as 0.03 μm Ra.
- AuSn layers with different compositions and thickness.
The requirements for more powerful semiconductor lasers
The requirements for more powerful semiconductor lasers both in pulsed and CW mode challenge the ability of traditional thermal management materials to quickly and efficiently dissipate heat. Contrary to injection molding technology, Spectra-Mat's unique technology to infiltrate copper in an highly homogeneous sintered tungsten matrix guarantees the homogeneity of thermal conductivity of the tungsten copper submounts along the three axes, a very important requirement for multi diodes lasers bars. The superior homogeneity of Spectra-Mat's tungsten copper material keeps the CTE stable from room temperature to over the soldering temperatures of the laser bars.
| W weight | CTE | Thermal conductivity |
|---|---|---|
| W 90% Cu 10% | 6.2 ppm/K @ 25C | 201 W/(m*K) |
| W 85% Cu 15% | 6.8 ppm/K @ 25C | 210 W/(m*K) |
| W 80% Cu 20% | 7.4 ppm/K @ 25C | 219 W/(m*K) |
| W 75% Cu 25% | 8.0 ppm/K @ 25C | 228 W/(m*K) |
| At 25 C, CTE of GaAs is 6.5 ppm/K and of GaN is 3.2 ppm/k. | ||
The recent developments of our dedicated refractory
composite plating process assure a stable flatness better than 0.3 μm per mm, minimizing the "smile" effect in laser diodes arrays. The final lapping of the bulk surface can enable different grades of surface roughness (better than 0.03 μm Ra) to optimize adhesion to the solder.
The tungsten copper submounts can be supplied plated for use of AuSn preform or with patterned or unpatterned AuSn metallization with AuSn solder of different compositions. AuSn layers with possible metal barrier layers can be deposited by sputtering, evaporation or jet process.
Edge radius quality is better than 15 μm, enabling the proper cooling of the emitting surface of the laser diode as well as avoiding any slipping of the laser diode at high temperature. The tight dimensional tolerances fit the strictest requirements for semiconductor lasers stacks.
