ABSTRACT Sintering refers to a process in which powdered materials are heated at high temperatures to form a solid mass. The process involves heating below the melting point to enhance strength and density and create electrical connections through particle adhesion. As semiconductor packaging becomes increasingly important in the current industry, advancements in sintering are essential. However, the oxide layer that forms on the surface of Cu during sintering hinders electrical conductivity and reduces adhesion performance, which can cause significant issues when used as semiconductor components. Therefore, removing this oxide layer is crucial to improving component performance. Various chemical etching methods are commonly employed to suppress and remove the oxide layer on the Cu surface. In this study, we suppressed the formation of the oxide layer using acid and compared the sintering performance using poly(acrylic acid) (PAA) with different molecular weights. Experiments were conducted to assess the effectiveness of oxide layer removal and the impact on the electrical and adhesive properties of the sintered Cu chips. To evaluate thermal stability among Cu particles, oxide layer removal efficiency, interparticle connectivity, adhesion, and electrical conductivity, we utilized analytical techniques such as thermogravimetric analysis (TGA), X‐ray photoelectron spectroscopy (XPS), X‐ray diffraction (XRD), scanning electron microscopy (SEM), lap shear strength tests, and four‐point probe measurements. The electrical conductivity showed the following results: Cu chip without activator had a conductivity of 1.0 × 10 4 S/m, that with acrylic acid (AA) had 7.9 × 10 3 S/m, that with PAA2k had 1.8 × 1 4 S/m, and that with PAA250k achieved 4.0 × 10 4 S/m. These results indicate that the electrical conductivity of the sintered Cu chips increased with increasing molecular weight of PAA. Furthermore, adhesion properties improved, and surface oxygen content decreased. These findings demonstrate that higher molecular weights of PAA lead to more effective removal of the oxide layer in sintered Cu chips. This study contributes to the research and development of Cu sintering in the semiconductor packaging industry and offers guidelines for selecting appropriate sintering additives and polymer molecular weights, thereby advancing semiconductor packaging technology.