Compliant Die Attach Process for High-Conformity Integration of Ultra-Thin Chips on Curved Surfaces

Advancements in free-form electronics demand robust bonding strategies for integrating ultra-thin silicon dies onto non-planar substrates. This study reports a compliant die attach process optimized for curved surfaces to achieve high surface conformity and minimal void formation. Bonding tools of varying materials and geometries [rigid/flat, rubber/flat, rigid/curved, and rubber/curved] are evaluated to assess their impact on bonding quality. Finite element method (FEM) simulations predicted stress distributions and contact mechanics, which are validated experimentally. Rubber/curved bonding tools exhibited superior compliance, resulting in uniform interfacial contact and reduced defect density. Process parameters such as bonding temperature, pressure, adhesive thickness, and annealing method are systematically refined. Integration of a pressure curing oven (PCO) enabled efficient gas evacuation and enhanced adhesive homogeneity. Distinct from prior approaches limited to planar or mildly curved substrates, this work addresses high-curvature integration through a combined simulation–experiment framework. The proposed process achieved void-free attachment with a curvature deviation below ±2.4% and a void ratio under 0.5% while maintaining mechanical integrity under thermal cycling. This framework provides a scalable and reliable platform for next-generation curved electronics, with specific applicability to LiDAR modules and wide-field of view (FoV) imaging systems.