Wiring Substrate with Graded Inorganic Filler for Crack Resistance
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Solution Overview
Problem
Existing wiring substrates face issues with stress concentration and cracking in resin insulating layers due to differences in thermal expansion coefficients between conductor pads and surrounding layers, leading to potential defects in component mounting cavities.
Innovation Solution
A wiring substrate design featuring a core substrate with build-up parts having alternating layers of resin insulating and conductor layers, where the first resin insulating layer has a lower inorganic filler content rate than other layers, reducing stress concentration and cracking risk, while other layers with higher inorganic filler content rates enhance thermal expansion matching and heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If inorganic filler is added to resin insulating layers to enhance thermal expansion matching and heat dissipation, then thermal performance is improved, but stress concentration and cracking risk increase due to material rigidity
Solution Approach 1:
The patent applies local quality by differentiating the inorganic filler content across different resin insulating layers. The first resin insulating layer (adjacent to the conductor pad) has a lower inorganic filler content rate to reduce stress concentration and cracking, while other resin insulating layers have higher inorganic filler content rates to enhance thermal expansion matching and heat dissipation. This localized variation in material composition allows each layer to optimize its properties for specific functional requirements.
Solution Approach 2:
The patent employs parameter changes by varying the inorganic filler content rate as a key parameter across different resin insulating layers. By controlling the inorganic filler content rate to be lower in the first resin insulating layer and higher in other layers, the patent achieves different thermal expansion coefficients and mechanical properties in each layer, thereby balancing stress reduction and thermal management objectives.
2Strength
If inorganic filler content rate is reduced in the first resin insulating layer to suppress cracking, then stress concentration is reduced, but thermal expansion matching and heat dissipation performance decrease
Solution Approach 1:
The patent resolves this contradiction through local quality by assigning different inorganic filler content rates to different layers based on their specific functional needs. The first resin insulating layer, which is most susceptible to stress concentration at the conductor pad interface, receives a lower inorganic filler content rate to prioritize crack resistance. Other resin insulating layers, which play a more significant role in thermal management, maintain higher inorganic filler content rates for optimal thermal expansion matching and heat dissipation.
Solution Approach 2:
The patent applies parameter changes by systematically varying the inorganic filler content rate parameter across different resin insulating layers. This parameter variation enables the first layer to have reduced stress concentration and cracking susceptibility, while other layers maintain enhanced thermal performance characteristics, thereby achieving an overall balance between mechanical strength and thermal management.
3Ease of manufacture
If uniform inorganic filler content rate is used across all resin insulating layers, then manufacturing is simplified, but stress concentration and thermal performance optimization are compromised
Solution Approach 1:
The patent addresses this contradiction by implementing local quality through differentiated inorganic filler content rates in different resin insulating layers. While this increases manufacturing complexity slightly, it significantly improves reliability by preventing stress concentration and cracking in the first resin insulating layer, which is critical for ensuring a defect-free component mounting cavity. The benefit of enhanced reliability outweighs the moderate increase in manufacturing complexity.
Solution Approach 2:
The patent applies parameter changes by varying the inorganic filler content rate parameter across different layers to optimize both stress distribution and thermal performance. This parameter differentiation, while adding some manufacturing complexity, ensures the formation of a reliable component mounting cavity free from defects such as cracks and stress concentration, thereby achieving superior overall reliability.
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 suppresses cracking in the first resin insulating layer and achieves desired thermal expansion properties and heat dissipation in the wiring substrate, ensuring a reliable and defect-free component mounting cavity.
Implementation Method 1
due to differences in thermal expansion coefficients between conductor pads and surrounding layers
Implementation Method 2
other layers with higher inorganic filler content rates enhance thermal expansion matching and heat dissipation
Data Source
AI summary
A wiring substrate includes a core substrate, and a build-up part laminated on the substrate and including resin insulating layers. The insulating layers include a first insulating layer, the build-up part includes a conductor layer on the first insulating layer, a second insulating layer on the first insulating layer and covering the conductor layer, and a recess penetrating through the second insulating layer and exposing portion of the conductor layer such that the conductor layer includes component mounting region that places an electronic component in the recess and a conductor pad forming bottom surface of the recess, the insulating layers include inorganic filler such that all insulating layers or all insulating layers other than the first insulating layer include the inorganic filler and that inorganic filler content rate of the first insulating layer is lower than inorganic filler content rate of the insulating layers other than the first insulating layer.