Why is underfill applied? Underfill provides a strong mechanical bond between the chip and the PCB's connection, protecting the solder joints from mechanical stress. It also helps transfer heat. Underfill softens the mismatch between the coefficient of thermal expansion (CTE) between the chip and the board.

What is the purpose of underfill material in flip chip technology?

WHAT is UNDERFILL AND WHY is it USEFUL? Underfill is thermoset epoxies traditionally used in flip chip applications to reduce thermal stresses solder bumps experience due to coefficient of thermal expansion mismatch between a die and the organic substrate.

What is no-flow underfill?

No-flow underfill processing uses fluxing underfills that are dispensed onto the substrate before flip chip placement. The chip is placed onto the dispensed underfill, causing squeeze flow of the material. The assembly is then reflowed and cured simultaneously in a standard solder reflow process.