Dual-Thickness Chip Package Lid for Crack-Resistant Assembly
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Mechanical cracks, such as underfill material cracks and adhesive delamination, occur in integrated chip packages during manufacturing, reliability tests, and field operations, which are not effectively addressed by existing technologies.
Innovation Solution
A dual thickness lid structure with modified foot portions and adhesive layer patterns is used to mitigate crack risk and improve thermal interface material coverage, optimizing the chip package structure to manage mechanical stress distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional uniform thickness lid structure is used, then manufacturing is simple, but mechanical cracks occur in underfill material and adhesive delamination happens during reliability tests
Solution Approach 1:
The lid structure employs varying thickness across different regions: a first thickness in the first region and a second thickness (different from the first) in the second region. This local quality variation allows the lid to provide enhanced mechanical support where needed while reducing stress concentration in other areas, thereby preventing underfill material cracks and adhesive delamination without requiring complete structural redesign
Solution Approach 2:
The patent changes the thickness parameter of the lid structure from uniform to non-uniform distribution. By adjusting the thickness parameter spatially across different regions of the lid, the design optimizes mechanical stress distribution during thermal cycling and reliability testing, effectively preventing crack formation and delamination while maintaining manufacturing feasibility
2Stability of the object's composition
If the lid structure is designed to cover the entire assembly, then mechanical stability is improved, but stress concentration occurs at corners causing cracks
Solution Approach 1:
The lid structure incorporates asymmetric design elements where the first region and second region have different thickness characteristics and spatial distributions. This asymmetry allows the structure to better accommodate the symmetric stress patterns during thermal cycling, distributing corner stresses more evenly and preventing the concentration of harmful stresses that would lead to cracks
Solution Approach 2:
The lid is segmented into at least two distinct regions with different thickness properties. This segmentation allows each region to independently manage stress in its specific zone, preventing the propagation of cracks from high-stress corner areas while maintaining overall mechanical stability of the assembly
3Strength
If adhesive layer covers the entire lid, then bonding strength is maximized, but manufacturing complexity and material cost increase
Solution Approach 1:
The adhesive layer is applied selectively only in the first region of the lid where bonding is required, rather than covering the entire lid surface. This local quality approach maintains necessary bonding strength at the interface between the lid and assembly while simplifying the manufacturing process and reducing adhesive material consumption in regions where bonding is not needed
Data Source
AI summary
A chip package structure includes an assembly containing an interposer and semiconductor dies; a packaging substrate attached to the assembly through solder material portions; and a lid structure attached to the packaging substrate. The lid structure includes: a first plate portion having a first thickness and located in an interposer-projection region having an areal overlap with the interposer in a plan view; a second plate portion having a second thickness that is less than the first thickness, laterally surrounding, and adjoined to, the first plate portion, and located outside the interposer-projection region; and a plurality of foot portions adjoined to the second plate portion, laterally spaced from the first plate portion, and attached to a respective top surface segment of the packaging substrate through a respective adhesive portion.