Eutectic Die Bonding 101

Eutectic Bonding - Why is it Necessary?

This Eutectic Bond consists of three key aspects:

1. The Electrical Contact
2. The Primary Heat Interface
3. The Mechanical Support 

Quick SCIENCE LESSON: The Law of Thermodymanics

1. Energy can neither be created nor destroyed (you can't win!)
2. 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.

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: