Devices in the developing
semiconductor market require high density,
high integration, and detailed processing. Conventional wire bonding
is inappropriate for fine-sized devices, and connected wires can be
damaged by heat generation and external physical impact. Soldering
is also used in advanced packaging technologies. However, disturbances
and overhead joints can occur during bonding. Thus, sintering has
been extensively utilized to overcome these drawbacks. Sintering pastes
are pressurized and bonded, resulting in stable bonding during sintering.
In this study, the composition of the Cu sintering material was examined
using diverse additives and solvents. We manufactured sintering materials
comprising Cu (1 μm), a solvent [methanol (MeOH), ethanol (EtOH),
or ethylene glycol (EG)] and an acidic additive (benzoic acid, phthalic
acid, or hexanoic acid). After the sintering process, the mechanical
and electrical characteristics were compared to determine the optimal
composition and bonding conditions. The optimum ratios between the
acid and solvent were 4:6 (MeOH and EtOH) and 2:8 (EG) due to the
high viscosity and effective long-term storage. All samples using
EtOH as the solvent exhibited the highest sintering performances.
The aromatic and carboxylic groups substantially improved the sintering
performance and increased the electrical conductivity. Based on the
O1s/Cu2p ratio (2.23%), the best sintering composition
was EtOH/PA, which showed the highest electrical conductivity (ca.
104 S/m) and strength (34.0 MPa). The sintering process
using various additives and solvents can be helpful to determine the
sintering conditions while maintaining the electrical properties.