Enabling Low Pressure, Low Temperature, and Particle Control for Anisotropic Conductive Adhesives

Abstract

AbstractAnisotropic conductive adhesives (ACAs) are the preferred interconnection technology for applications that employ large dies, flexible substrates, and ultra fine‐pitch interconnects. Conventional ACAs require relatively high bonding pressures and temperatures, and ultra fine‐pitch applications challenge the trade‐off between low interconnect resistance and risk of short circuits. This study introduces an ACA‐like interconnection technology that addresses these limitations, allowing for low‐pressure, low‐temperature assembly processes with enhanced particle control at the interconnects. Conductive particles are deposited onto a patterned carrier and subsequently transferred to electrical pads using either non‐conductive film or Ag sintering. The Ag sintering process is performed at a low temperature (140 °C) and low bonding pressure (1 N for a 10 × 10 mm2 chip). The capability of controlling the position and number of conductive particles within individual interconnects is demonstrated. This presents possibilities for achieving ultra‐fine pitch interconnects with negligible risk of short circuits, without compromising electrical resistance. It is demonstrated that interconnect resistance can be tuned by varying the number of conductive particles (achieving a resistance as low as 33 mΩ with 25 particles per interconnect). This approach is applicable to scenarios where the bonding force and temperature must remain low due to the nature of substrate materials.