Compliant Interconnects Based on Single Micrometer-sized Metal-Coated Polymer Spheres

Area of Science:

• Materials Science
• Electrical Engineering
• Nanotechnology

Background:

• Multifunctional electronics require advanced interconnection technologies for high-density, ultrafine pitch applications.
• Existing methods face challenges with high bonding forces and thermo-mechanical stress due to material mismatches.
• There is a need for robust, compliant interconnects suitable for large dies.

Purpose of the Study:

• To propose and demonstrate a novel compliant interconnect approach for high-density electronics.
• To address the limitations of current interconnection technologies regarding force and thermal stress.
• To enhance the thermo-mechanical robustness and interconnect performance for advanced packaging.

Main Methods:

• Utilizing single micrometer-sized metal-coated polymer spheres as interconnects.
• Employing low-temperature (140 °C) and low-pressure (∼15 mN/particle) sintering of silver (Ag) nano ink for joining.
• Demonstrating controlled particle placement and achieving high success rates in individual interconnects.

Main Results:

• Achieved a 98% success rate in forming individual interconnects with controlled particle capture.
• Sintered Ag nano ink secured particles with adhesion force > 2 μN and reduced interconnect resistance by 15%.
• Measured interconnect resistance as low as 0.5 Ω, offering an alternative to traditional metallurgical joints.

Conclusions:

• The proposed method offers a viable, compliant interconnection technology for high-density, ultrafine pitch applications.
• Low bonding pressure and temperature enhance thermo-mechanical robustness and reduce package stress.
• This approach provides an alternative to metallurgical joints, improving performance and reliability in electronic packaging.