Eutectic Bonding - Why Is It Necessary?
This Eutectic Bond consists of three key aspects:
- The Electrical Contact
- The Primary Heat Interface
- The Mechanical Support
Quick SCIENCE LESSON: The Law of Thermodymanics
- Energy can neither be created nor destroyed (you can't win!)
- Energy flows from a higher energy state to a lower energy state (hot or cold) **in the event of a tie, mother nature wins!
Eutectic Bonding - What Does It Prevent?
Catastrophic Optical Damage (COD): damage to the mirror coating reflects energy back in to the laser and overheats over time
Reduced Device Longevity: poor thermal interface will require higher current input for desired light output
"Noise" Feedback: adhesive bonds provide noisy feedback at data rates > 40 Gps
Eutectic Definition: Easily Melted
*Point "E" is the mixture point where heating the solder results in pure solid to pure liquid transition 
How to Join with Solder: 2 Things Needed
HEAT and WETTING: 1) Need sufficient heat to melt and reflow the solder and 2) Don't want excessive heat that will damage the components OR the surrounding components.
Wetting vs. Non-Wetting
Solder droplet contact angle "0" affects wetting.
Process Variables in Eutectic Bonding
It's important to keep in mind some of the process variables with eutectic bonding. Palomar Technologies' eutectic process can control the following:
- Temperature
- Time
- Force scrub
- Gas environment
Other variables, not controlled with Palomar's process:
- Die material
- Solder material
- Solder size
- Solder presentation method
- Substrate/bond pad material
- Cleaning methods
Learn more:
Download the "Automated Eutectic Die Attach" eBook: 
