Rheology-Optimized Photosensitive Ceramic Paste Based on P(MMA- <i>co</i> -MAA) for High-Resolution Photolithography of Low-Temperature Co-Fired Ceramic Vias

The fabrication of through-vias in low-temperature co-fired ceramic (LTCC) substrates is limited by the poor resolution, low efficiency, and high cost of conventional laser drilling and mechanical punching. Here, a photosensitive ceramic paste (PSCP) based on a molecularly tailored poly(methyl methacrylate-co-methacrylic acid) (P(MMA-co-MAA)) prepolymer is developed through combined polymer design and rheological engineering to enable high-resolution photolithographic patterning. By optimizing the MMA/MAA molar ratio to 4:1, the photosensitive resin achieves a pattern resolution of 5.47 μm. A P(MMA-co-MAA) content of 30 wt % provides an optimal viscoelastic balance for uniform spin-coating, while incorporation of 50 wt % ceramic solids forms a stable composite network that ensures pattern fidelity during exposure and development. As a result, vias with a minimum diameter of 31.90 μm and steep sidewalls are obtained at a low exposure dose of 20 mJ/cm2, outperforming a commercial benchmark paste in both resolution and sidewall verticality. This work establishes a practical materials and rheology design strategy for high-resolution photolithography patterning in high-solid-loading ceramic systems, paving the way for advanced LTCC and related electronic packaging technologies.