Wiring Substrate with Composite Insulation Layers for Warpage Control
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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 higher number of through electrodes, which splits the reinforcement material and lowers the substrate's mechanical integrity.
Innovation Solution
A wiring substrate design that includes a core substrate with thermosetting insulative resin-based insulation layers on both surfaces, featuring a via wire structure with a photosensitive resin-based third insulation layer and a wiring layer, which enhances mechanical strength and reduces warpage by distributing stress and improving adhesion between layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the core substrate is thinned to reduce wiring substrate thickness, then the overall substrate thickness is reduced, but the mechanical strength and rigidity of the core substrate decrease
Solution Approach 1:
The patent uses composite insulation layers combining thermosetting resin with reinforcement materials (glass fibers or carbon fibers) to achieve high mechanical strength in thin substrates. The composite structure provides both the necessary rigidity for thinning and the structural integrity required for withstanding manufacturing and operational stresses.
Solution Approach 2:
The patent applies reinforcement materials locally within the insulation layers to provide targeted mechanical support. The insulation layers containing reinforcement materials are positioned at critical locations to compensate for the reduced core substrate thickness, providing local strengthening where needed most.
2Adaptability or versatility
If the number of through electrodes is increased to accommodate more terminals, then the terminal density is improved, but the reinforcement material is split more extensively, lowering mechanical strength
Solution Approach 1:
The composite insulation layers with reinforcement materials provide a matrix that distributes and absorbs the stress caused by multiple through electrodes. The reinforcement fibers bridge across the through electrode holes, preventing crack propagation and maintaining mechanical strength even with high terminal density requirements.
Solution Approach 2:
The insulation layers are segmented into multiple thin layers with reinforcement materials distributed throughout. This segmentation allows the structure to accommodate multiple through electrodes by providing discrete reinforcement zones that maintain overall structural integrity while allowing local modifications for additional terminals.
3Length of stationary object
If the core substrate is thinned, then the wiring substrate becomes thinner, but warpage is more likely to occur due to reduced rigidity
Solution Approach 1:
The thermosetting resin composite with reinforcement materials provides high stiffness-to-thickness ratio, enabling the substrate to maintain flatness and resist warpage even when thinned. The composite structure's inherent stability prevents dimensional changes during manufacturing and operation.
Solution Approach 2:
The patent changes the material parameters of the insulation layers by using thermosetting resins with specific mechanical properties and reinforcement material configurations. These parameter changes increase the flexural modulus and reduce the coefficient of thermal expansion, thereby improving warpage resistance in thin substrates.
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 maintains sufficient rigidity and reduces warpage in the wiring substrate, even with reduced thickness, by compensating for the decreased core substrate strength and improving adhesion between layers, thus preventing delamination and undulation.
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
The main component of the third insulation layer is a photosensitive resin
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 formed from a thermosetting insulative resin respectively including first and second reinforcement materials, and a via wire formed in the first insulation layer. The second wiring structure includes a third insulation layer formed on an upper surface of the first insulation layer and an upper end surface of the via wire, and a wiring layer extended through the third insulation layer and electrically connected to the via wire. The outermost insulation layer, the main component of which is a photosensitive resin, is stacked on a lower surface of the second insulation layer. The second wiring structure has a higher wiring density than the first wiring structure. The first reinforcement material is partially exposed on the upper surface of the first insulation layer.