High-power laser diodes assembly by Quantel Laser help achieve important scientific tasks aboard Mars-exploring “Curiosity” rover. They were assembled on precision die bonders by Finetech.
After the first moon landing, space exploration has been developing at a rapid pace. Since 2012, the “Curiosity” rover, equipped with scientific instruments containing high-power lasers, has been investigating the geology and climate on Mars as part of NASA’s MSL mission. From the Chemistry and Camera complex (ChemCam) to tunable laser spectrometers – the significance of QCW laser diodes is hard to underestimate.
Specifically designed for application in space, these laser diode arrays were manufactured by the French company Quantel – today one of the largest producers of high power solid-state lasers worldwide and a long-term partner of Finetech.
Higher yield, better power output
At the beginning of our collaboration, Finetech worked with Nyvonix Europe, a small company producing laser diodes and laser bars for industrial purposes. Soon after, in 2006, it was acquired by the Quantel Group to become its Quantel Laser division. Today, Quantel Laser is a division of the Lumibird Group.
The company had approached Finetech with a need to extend their laser bar bonding capabilities with extremely high bonding quality requirements in combination with higher placement accuracy. They had been manufacturing laser diode modules in small series before, but their planned shift to full volume production imposed stricter demands. Part of the intended transfer was to enhance the existing production process with a new machine which would ensure higher yields. This is where Finetech’s years of experience in precision machine engineering for advanced packaging came into play.
Keeping the smile in check
Quantel was looking for a new, manually-operated production die bonder which would ensure the highest precision. Their plan involved laser bar assembly on a heat sink, with accurate lateral and overhang positioning and outstanding control of the laser SMILE effect.
- Accurate placement of laser bars up to 2 x 10 mm2 with a thickness of 0.15 mm onto a heat sink with a thickness between 0.3 mm and 2 mm.
- Alignment of both laser bar edges to the edge of the heat sink with a defined overhang, requiring accuracy better than 2 microns.
- Eutectic AuSn soldering process in controlled atmosphere with defined solder layer thickness and outstanding uniformity.
Challenges mean development
Finetech has always been open to tackle challenges with a solution-oriented approach. That is why a special tool was designed according to the Quantel requirements, which would allow previewing the pre-positioning of the heating sink on the heating plate. A combination of features presented the desired solution:
- Highest placement accuracy due to the FINEPLACER® principle
- High-resolution optical system
- Two-point alignment capability
- Operator-independent bonding process with closed-loop automatic bonding force control
- Custom-tailored heating plate with rapid heating and cooling cycles
- Specifically developed microscope for post-bond facet inspection
- Compensating tolerances in submount dimensions
Quantel visited Finetech several times to be fully involved in sample testing as well as development of specific parts.
Together, we achieved a better power output by finding ways to reproducibly place and bond the laser bars with exactly defined overhangs. We could also increase production volume and yield and a more uniform heat distribution ensured higher stability.
As a consequence of the collaboration, Quantel acquired a flexible, sub-micron Finetech die bonder which would become an integral part of their production process. Five years later, continued excellent results encouraged them to acquire another Finetech system.
