Laser Bar Bonding

R&D and production bonders by Finetech are equipped to perform high accuracy laser bar assemblies, including placing and bonding laser bars to sub-mounts and sub-assemblies to heat sinks. As opposed 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 in a wide range of applications.

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

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

What are the challenges?

Handling:

  • Fully-automatic processes
  • Sensitive components with brittle materials and optically active areas
  • Delicate edges and facettes
  • High magnification need for the complete length of the laser bar/submount

Process:

  • Perfect coplanarity required to ensure proper thermal management
  • Highest placement accuracy needed to ensure defined overhang
  • Automatic 2-point alignment of long components for perfect angle precision
  • Short cycle times with ultrafast heating capability
  • Solder materials are prone to oxidation; process gas integration required
  • Stacked mounting (lasers to submount) requires different solder materials with appropriate profiles

Result:

  • Cooling issues caused by bonding voids
  • Deformation of laser bar results in decreased emitting power (SMILE)
  • Thermal warpage shortens lifespan of the component
  • Deformed laser bar (SMILE)
    Deformation (SMILE) - The higher the SMILE value, the more affected is the beam quality of the optical system
  • Inhomogenous Cooling of laser bar (Hot Spots)
    Temperature distribution (HOTSPOT) - Faulty or inhomogeneous solder layers can cause local temperature fluctuations that may result in breakdown of single emitters
  • Thermo-mechanical Warpage in laser bar (Stress)
    Warpage(STRESS) - Mechanical pressure or strain warpage may result in shortened lifespan

Error Examples

  • Deformation (SMILE)
    The higher the SMILE value, the more the beam quality of the optical system is affected
  • Temperature distribution (HOTSPOT)
    Faulty or inhomogeneous solder layers can cause local temperature fluctuations that may result in breakdown of single emitters
  • Warpage(STRESS)
    Mechanical pressure or strain warpage may result in shortened lifespan

The Finetech Solution

Tools & Modules

  • laser bar bonding tool
    Laser bar tool

  • Automatic Bonding Force Module provides controlled forces and secure handling
  • Active and passive self-levelling tools guarantee even bond line, preventing SMILE effects
  • Unique vision system, in combination with pivoting placement arm, minimizes alignment and placement error
  • Process gas integration to reduce/avoid oxidation and increase quality of bonding
  • IPM allows comprehensive process control and reproducible processes

Step-by-step: Complete Laser Bar Assembly Process

  1. Load submount on heating module
  2. Pick-up laser bar from presentation
  3. Align laser bar to sub-mount
  4. Place and bond laser bar to sub-mount (i.e. using AuSn)
  5. Pick-up sub-assembly
  6. Load heat sink on heating module (i.e. CS-mount)
  7. Align sub-assembly to heat sink
  8. Place and bond sub-assembly to heat sink (i.e. using Indium)
  9. Mount N-contact sheet to top face of laser bar (i.e. InSn)

Process Gas Integration

Process gas integration for bonding

  • Sophisticated support of AuSn and Indium joints under defined atmosphere
  • Employment of formic acid as a process gas for shielding and reduction of oxide layers
  • Self-sufficient formic acid gas generation
  • Safe handling of fluid formic acid
  • Numerous standard and custom process gas integration methods with controlled injection and outlet
  • Automatic control of activation time and concentration for repeatable results

FINEPLACER® Production Bonder

  • FINEPLACER® femto 2
    Automated Prototype2Production Bonder

FINEPLACER® systems for production environments enable highly stable automated assembly processes with the focus on maximum yield. They feature a high degree of configurability for a wide spectrum of technologies and applications.

Our team will be happy to assist you with finding the best equipment solution for your production requirements.

FINEPLACER® Laboratory Bonder

  • FINEPLACER® sigma
    Semi-automated sub-micron bonder
  • FINEPLACER® lambda
    Flexible sub-micron die bonder
  • FINEPLACER® pico ma
    Multi-purpose die bonder
  • FINEPLACER® matrix ma
    Semi-automated die bonder

Due to the modular design approach, FINEPLACER® laboratory bonding systems can be configured for virtually any application challenge.

The main distinguishing features between the machines are the

  • degree of motorisation
  • optical resolution
  • placement accuracy and
  • working area

Our team will be happy to assist you with finding the best equipment solution for your specific application requirements.

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