Circuit Board Auxiliary Layer Warpage Control
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Solution Overview
Problem
The challenge in the IT industry is the increased risk of warpage in circuit boards due to differences in physical properties such as stiffness and thermal expansion characteristics when multiple chips are mounted in a single package, which can lead to manufacturing issues during the production of package circuits or finished package substrates.
Innovation Solution
A circuit board design that includes a substrate with a first insulation layer, a first wiring layer, and a protective layer, along with an auxiliary layer that overlaps the boundary areas between element mounting portions, providing higher strength and compensating for physical property differences, and a manufacturing method that involves stacking a mask layer, forming the auxiliary layer and link pads, and removing the mask layer to enhance warpage control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple chips are mounted in one package to achieve large-capacity fast information processing, then processing capacity is improved, but warpage risk increases due to differences in physical properties such as stiffness and thermal expansion characteristics
Solution Approach 1:
An auxiliary layer is introduced as an intermediary component between the substrate and the protective layer. This auxiliary layer has higher strength than the protective layer and is disposed to overlap at least a part of a first boundary area including a region between element mounting portions, serving as a mediator to compensate for physical property differences and reduce warpage risk while allowing multiple chips to be mounted in one package
Solution Approach 2:
The auxiliary layer is strategically positioned to overlap the boundary area between element mounting portions rather than uniformly distributed across the entire substrate. This local placement provides targeted support where warpage is most likely to occur, improving reliability at critical locations while maintaining the overall structure for high-capacity processing
2Productivity
If an interposer is used to mount multiple chips, then packaging capacity is improved, but warpage occurs due to physical property differences
Solution Approach 1:
The auxiliary layer is designed with specific parameters including higher strength than the protective layer, specific thickness (smaller than link pad thickness), and specific material properties. These parameter changes allow the auxiliary layer to compensate for physical property differences between chips and substrate, maintaining shape stability while enabling high-capacity packaging with interposers
3Reliability
If the auxiliary layer is added to reduce warpage, then reliability is improved, but device complexity increases
Solution Approach 1:
The auxiliary layer is implemented as a thin film structure with thickness smaller than the link pad thickness, allowing it to be integrated within the existing layer structure. This thin film approach provides warpage control and reliability improvement without significantly increasing device complexity, as the auxiliary layer can be formed using standard thin film deposition processes
4Manufacturing precision
If the auxiliary layer thickness is reduced to match link pad thickness, then manufacturing precision is improved, but structural strength is reduced
Solution Approach 1:
The auxiliary layer has different thickness characteristics in different regions: it is thinner than the link pad thickness in the boundary area where it overlaps with the protective layer, but maintains sufficient strength in the warpage inflection area. This local quality variation allows the auxiliary layer to provide both manufacturing precision and structural strength where needed
Data Source
AI summary
The disclosed circuit board includes: a substrate portion that includes a first insulation layer and a first wiring layer buried by the first insulation layer, and a first element mounting portion and a second element mounting portion disposed on an upper surface of the substrate portion; a first protective layer disposed on the substrate portion; and an auxiliary layer that is disposed to overlap at least a part of a boundary area including a region between the first element mounting portion and the second element mounting portion, and has higher strength than the first protective layer.