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.

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: