Heterogeneous Substrate Core Warpage Control
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Solution Overview
Problem
Thinner package substrates in 2.5D/3D stacked die packages face challenges in warpage control, which affects manufacturing and interconnect reliability due to reduced rigidity, and existing solutions like increased BGA geometry or stiffeners may not facilitate thinner substrates effectively.
Innovation Solution
A heterogeneous substrate core with varying thickness sections and materials, including a first core layer with multiple layers and a second core section with fewer layers, providing tunable warpage control through different dimensions and positioning of plated through hole vias, and optional stiffeners for additional rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If package substrate core thickness is reduced to meet thinner substrate requirements, then substrate thickness specification is improved, but warpage control deteriorates due to reduced rigidity
Solution Approach 1:
The substrate core is divided into multiple layers with different thicknesses - a first core layer and a second core layer - where each layer provides localized rigidity support. This heterogeneous structure allows the substrate to maintain overall thinness while having specific regions with enhanced mechanical properties to control warpage during manufacturing and assembly.
2Stability of the object's composition
If BGA geometry is increased (greater diameter and pitch distance) to mitigate warpage, then warpage control is improved, but package substrate footprint expansion occurs
Solution Approach 1:
Instead of uniformly increasing BGA geometry across the entire substrate, the invention uses localized core layer structures that provide warpage control in specific regions. This allows maintaining standard BGA pitch and diameter while achieving warpage control through the heterogeneous core architecture.
3Stability of the object's composition
If package stiffener is added to control warpage, then warpage control is improved, but additional space and increased z-height are required
Solution Approach 1:
The warpage control function is merged into the substrate core structure itself by creating a heterogeneous multi-layer core. This integrates the stiffening function directly into the substrate rather than adding a separate stiffener component, thereby controlling warpage without increasing overall z-height or requiring additional mounting space.
4Stability of the object's composition
If heterogeneous substrate core with varying thickness sections is used, then warpage control is improved, but device complexity increases
Solution Approach 1:
The substrate core is segmented into discrete layers (first core layer and second core layer) with different thicknesses and material properties. This segmentation allows independent optimization of each layer for specific functions while maintaining a relatively simple overall structure that can be manufactured using standard multi-layer substrate fabrication processes.
Data Source
AI summary
According to the various aspects, a package substrate with a heterogeneous substrate core including a first core layer that is coextensive with the package substrate and extends through a first section and a second section of the substrate core, in which the first section is adjacent to and thicker than the second section. The first section having at least a second layer and/or a third layer to provide the difference in thickness with the second section.