Laser Bar Bonding

In comparison to single lasers, laser bars consist of several single edge-emitting lasers comprised in a silicon bar. Bundling the light results in significantly increased output power as needed in a wide range of applications.

Laser bars are high power products, applied wherever small and efficient light-emitting units are needed. They mainly serve as pumping sources for optical resonators of high power lasers. Another field of use can be found in medical appliances.

Laser bar bonding on heat sink
Cross section of bonded laser bar

What are the challenges?

Sensitive components with brittle materials and optically active areas
Delicate edges and facettes
Perfect coplanarity required to ensure proper thermal management
Highest placement accuracy needed to ensure defined overhang
Stacked mounting (lasers to submount) requires different solder materials with their appropriate profiles
Void free bonding
Solder materials are prone to oxidation, process gas integration required
High magnification of large components
Indium bonding under process gas atmosphere

The Finetech Solution

Tools & Modules

Laser bar tool

Automatic Bonding Force Modules provide control of force
Active and passive equalization tools guarantee even bond line
Unique fixed beam splitter, in combination with rotating placement arm, minimize placement error
2-point-alignment of long narrow components by scanning with movalble optics slide
Full-automatic process with substrate and component handling
Pattern recognition to find edges to coincide

Step-by-step: Complete Laser Bar Assembly Process

Align laser bar to silicon submount
Bond laser bar on submount using gold/tin (Au/Sn) to produce subassembly
Align subassembly to metallic heatsink
Place and bond subassembly to heatsink using Indium
If needed, mount top contact

Process Gas Integration

Sophisticated support of AuSn and In joints under defined atmosphere
Process gas for shielding and oxide layer reduction
Self-sufficient formic acid gas generation
Safe handling of fluid formic acid
Numerous standard and custom process gas enclosures with controlled injection and outlet
Automatic control of activation time and concentration for reproducible results

Integrated Process Management (IPM)

Integrated Process Management (IPM)
Principle of process gas integration
Operating software for bonding

The Integrated Process Management (IPM) is the center piece of a FINEPLACER^® system¹ - the place where it all comes together. IPM is more than just thermal management. It synchronizes the control of all process modules and their related parameters:

Controlled and precisely balanced interaction of top and bottom (pre-)heating and cooling
Control of temperature, time, force, power, energy, flow
Controlled process gas integration for reduced solder contamination, minimized surface tension effects and smooth spherical solder residues

IPM is very complex, yet easy to access. Via the GUI of the operating software, the user has perfect control of all required adjustments. Just drag 'n drop to define temperature ramps or activate process modules. All settings are represented in only one profile, making for a very intuitive work flow.

The operating software provides an ever-growing library of profiles for all kinds of processes. It also offers comprehensive data logging functions essential for statistical process control.

In combination with the system-to-system process transfer capability this is as easy as process development can get.

¹ _{FINEPLACER^® core offers co-ordinated top and bottom heating but does not support IPM}