Packaging Substrate Stress-Absorption Trench for Underfill Cracking

The patent introduces a stress-absorption trench as an intermediary structure between the underfill material and the packaging substrate. This trench acts as a mediator that absorbs and distributes the mechanical stress generated by the underfill material, preventing direct stress transmission to the substrate that would cause cracking.

The patent modifies the physical structure of the packaging substrate by creating a trench with specific depth and width parameters. By changing the geometric parameters of the substrate surface (introducing a recessed region), the stress distribution parameters are altered, allowing the underfill material to bond effectively while reducing harmful stress concentrations.

The patent applies segmentation by dividing the packaging substrate surface into distinct regions: flat bonding areas for chip module attachment and recessed trench areas for stress absorption. This segmentation allows the substrate to perform multiple functions (bonding and stress management) without requiring completely new structural designs.

The trench structure implements local quality by creating a specific regional feature (the recessed area) with different geometric properties than the surrounding substrate. This localized modification provides stress absorption functionality only where needed, rather than requiring complex global structural changes throughout the entire substrate.