Coreless Substrate Warpage Reduction via Molding Resin and Interposer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional coreless substrates for electronic component mounting are prone to warpage due to low rigidity, which can lead to chip delamination during mounting and thermal stress-induced deformation, as they lack a core substrate to provide structural support and uniform thermal expansion properties.
Innovation Solution
A multilayer wiring board structure with a coreless substrate covered by a molding resin, excluding specific pad portions, to enhance rigidity and prevent stress propagation, and optionally using an interposer with matching thermal expansion to the chip for further stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a coreless substrate structure is used to reduce thickness, then the package thickness is reduced, but the rigidity decreases causing warpage during chip mounting
Solution Approach 1:
The patent uses a composite structure combining a coreless substrate with an interposer and molding resin. The interposer (made of ceramic, metal, or polymer) is bonded to the coreless substrate to form a composite structure that provides the necessary rigidity and thermal expansion matching, while maintaining the thin profile advantage of the coreless design.
Solution Approach 2:
The interposer acts as an intermediary component between the chip and the coreless substrate. It provides mechanical support and rigidity to the otherwise flexible coreless substrate, preventing warpage during chip mounting while allowing the overall package to remain thin.
2Reliability
If an interposer with matching thermal expansion is introduced, then thermal stress and warpage are reduced, but the device complexity increases
Solution Approach 1:
The interposer serves multiple functions simultaneously: it provides mechanical rigidity to prevent warpage, matches thermal expansion coefficients to reduce thermal stress, and enables proper chip mounting. This multi-functionality justifies the additional component by delivering multiple benefits from a single element.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces warpage and ensures reliable chip mounting by reinforcing the substrate with molding resin and using an interposer to match thermal expansion, preventing delamination and enabling high-density packaging.
Implementation Method 1
the rigidity of the overall substrate is improved, and thus propagation of a stress, if any, through the substrate can be effectively prevented
Implementation Method 2
use of an interposer with matching thermal expansion to the chip for further stability
Implementation Method 3
baking (heat treatment) is performed in order to heat-cure the underfill resin
Data Source
AI summary
An electronic component mounting package includes a structure (coreless substrate) in which a plurality of wiring layers are stacked one on top of another with insulating layers interposed therebetween and are interconnected through via holes formed in the insulating layers. The entire surface of the coreless substrate, exclusive of pad portions defined at desired positions of the outermost wiring layers thereof, is covered with a molding resin. Further, an interposer is mounted on the side of the electronic component mounting surface of the coreless substrate, and the molding resin is partially filled into a gap between the coreless substrate and the interposer.