Coreless Substrate Stiffener Layer for Warpage Control
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Solution Overview
Problem
Conventional semiconductor package structures face challenges in miniaturization and densification, leading to increased manufacturing costs and insufficient supportability and flatness, particularly when subjected to high temperatures, which can cause warpage issues during the package process.
Innovation Solution
A package structure comprising a first and second redistribution structure with a stiffener layer in a region of lower circuit density, allowing for direct build-up and reduced overall thickness, enhanced supportability, and improved flatness through the use of dielectric layers and redistribution circuits, with the stiffener layer separated from the redistribution circuits by dielectric layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the coreless package substrate is thinned to achieve miniaturization, then the package size is reduced, but the supportability and flatness deteriorate
Solution Approach 1:
The substrate is divided into two functional regions: a thinned coreless region for miniaturization and a stiffener region with increased thickness for structural support. This segmentation allows simultaneous achievement of small overall size and sufficient local supportability.
Solution Approach 2:
Different regions of the substrate have different thicknesses and structural properties. The stiffener region has greater thickness and enhanced mechanical properties compared to the thinned active region, providing localized support where needed while maintaining miniaturization in the functional area.
2Volume of moving object
If the substrate is thinned for miniaturization, then the package dimensions are reduced, but warpage increases under high temperature
Solution Approach 1:
The substrate is segmented into a thinned active region and a thicker stiffener region. The stiffener region acts as a thermal and mechanical anchor that resists warpage during high-temperature soldering processes while the active region remains thin for miniaturization.
Solution Approach 2:
The substrate employs a composite structure combining thinned substrate material with a stiffener region that has enhanced mechanical and thermal properties. This composite approach provides thermal stability and warpage resistance during processing.
3Reliability
If conventional drilled sequential lamination is used to laminate redistribution structures, then interlayer connections are achieved, but the overall thickness cannot be reduced and manufacturing cost increases
Solution Approach 1:
Multiple redistribution structures are merged and laminated directly onto each other in a sequential build-up process, eliminating the need for traditional drilled interlayer connections. This direct lamination approach reduces overall thickness while maintaining electrical connectivity through the dielectric layers.
Solution Approach 2:
The redistribution structures are connected through the dielectric layer plane rather than through vertical drilling. This dimensional approach to connectivity allows for thinner overall structure while achieving the same interlayer electrical connection function.
4Productivity
If high circuit density is achieved through multi-layer construction, then wiring area is expanded, but the substrate becomes thinner and less supportive
Solution Approach 1:
The substrate is segmented into a thin active region for high-density circuit routing and a thicker stiffener region for structural support. This allows multi-layer high-density wiring in the active region without compromising overall substrate supportability.
Solution Approach 2:
The substrate has locally differentiated properties: the active region is thin to accommodate high-density circuits, while the stiffener region is thicker to provide mechanical support. This local quality variation enables both high circuit density and adequate supportability.
Data Source
AI summary
A package structure that includes a first redistribution structure and a second redistribution structure is provided. The first redistribution structure includes a first dielectric layer, and a first redistribution circuit in the first dielectric layer. The second redistribution structure includes a first portion on the first redistribution structure and a second portion on the first portion, and each of the portions is electrically connected to the first redistribution structure and the first portion, respectively. The circuit density of the second portion is lower than that of the first portion. The first portion includes a second dielectric layer having a second redistribution circuit therein. The second portion includes a third dielectric layer having a third redistribution circuit therein. The third dielectric layer has a stiffener layer, which is separated from the third redistribution circuit by the third dielectric layer. A method of forming a package structure is also provided.