Wiring Substrate Composite Reinforcement Warpage Reduction
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Solution Overview
Problem
The mechanical strength of build-up wiring substrates decreases when the core substrate is thinned, leading to reduced rigidity and increased warpage due to the increased number of through electrodes, which compromises the integrity of the substrate.
Innovation Solution
A wiring substrate design incorporating a core substrate with reinforcement materials in thermosetting insulative resins, alternating layers of photosensitive and thermosetting insulative resins, and strategically positioned via wires to enhance mechanical strength and reduce warpage, along with a solder resist layer to manage thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the core substrate is thinned to reduce substrate size, then the substrate size is reduced, but the mechanical strength of the core substrate decreases
Solution Approach 1:
The patent uses composite materials by incorporating reinforcement materials (such as glass fibers) into the insulative resin layers. The core substrate and insulative layers are composed of resin matrices combined with reinforcing fibers, creating a composite structure that provides high mechanical strength despite thin substrate thickness. This allows the substrate to be thinned while maintaining structural integrity through the reinforced composite construction.
2Productivity
If the number of through electrodes is increased to accommodate more terminals, then the terminal density is improved, but a larger amount of reinforcement material is split and mechanical strength is lowered
Solution Approach 1:
The patent applies local quality by strategically positioning reinforcement materials and via wires at specific locations where mechanical strength is most needed. Instead of uniformly distributing reinforcement throughout the substrate, the design places reinforcement layers and via wires at critical stress points and interfaces, providing localized strengthening that compensates for the mechanical strength reduction caused by multiple through electrodes.
Solution Approach 2:
The patent employs composite materials in the insulative layers containing reinforcement materials that compensate for the strength loss from multiple through electrodes. The combination of resin and reinforcement fibers creates a composite structure that maintains mechanical strength even when numerous through electrodes split the reinforcement material.
3Volume of moving object
If the mechanical strength of the core substrate is lowered, then the substrate can be thinned, but the rigidity of the build-up wiring substrate is lowered and warpage is generated
Solution Approach 1:
The patent uses composite materials with reinforcement fibers embedded in the insulative resin layers to maintain rigidity and prevent warpage. The reinforced composite structure provides sufficient stiffness to the thinned substrate, preventing deformation and warpage that would otherwise occur due to reduced substrate thickness and lowered mechanical strength.
Solution Approach 2:
The patent addresses the rigidity problem by adding structural elements in the thickness dimension through stacked insulative layers and via wires. Instead of relying solely on substrate thickness for rigidity, the design creates a multi-layered composite structure where reinforcement materials and via wires provide structural support in the vertical dimension, compensating for the reduced horizontal thickness.
4Productivity
If denser and finer wiring patterns are implemented, then the wiring density is improved, but the mechanical strength and rigidity requirements become more stringent
Solution Approach 1:
The patent employs reinforced composite insulative layers that provide enhanced mechanical strength to support denser and finer wiring patterns. The reinforcement materials within the insulative layers create a rigid foundation that can accommodate high-density wiring without compromising structural integrity, allowing finer pitch wiring while maintaining necessary mechanical strength and rigidity.
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 design effectively maintains substrate rigidity, reduces warpage, and ensures reliable electrical connectivity by balancing the mechanical and thermal properties across the substrate layers.
Implementation Method 1
a first insulation layer stacked on an upper surface of the core substrate and formed from a thermosetting insulative resin including a first reinforcement material
Implementation Method 2
a plurality of third insulation layers, of which the main component is a photosensitive resin, formed on an upper surface of the first insulation layer
Data Source
AI summary
A wiring substrate includes first and second wiring structures. The first wiring structure includes a core substrate, first and second insulation layers each formed from a thermosetting insulative resin including a reinforcement material, and a via wire formed in the first insulation layer. The second wiring structure includes a wiring layer formed on upper surfaces of the first insulation layer and the via wire, an insulation layer formed on the upper surface of the first insulation layer, and an uppermost wiring layer including a pad used to electrically connect a semiconductor chip and the wiring layer. An outermost insulation layer stacked on a lower surface of the second insulation layer exposes a portion of a lowermost wiring layer stacked on the lower surface of the second insulation layer as an external connection pad. The second wiring structure has a higher wiring density than the first wiring structure.