Wiring Board With Permittivity Gradient Insulating Films
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Solution Overview
Problem
In Package on Package (PoP) technology, the insertion loss of signals through through mold vias is increased due to the inhomogeneous distribution of substances with different permittivities, particularly when inorganic fillers and molding resins with different permittivities are used, leading to scattering of radio waves and increased signal loss.
Innovation Solution
A wiring board configuration featuring a through via surrounded by a first insulating film with a higher permittivity, a second insulating film with a lower permittivity, and a filler-containing resin, where the second insulating film is positioned to trap radio waves, reducing insertion loss by optimizing the permittivity gradient and film thicknesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If inorganic fillers are added to molding resin to match thermal expansion coefficients, then thermal expansion compatibility with Si components is improved, but insertion loss of high-frequency signals increases due to permittivity differences
Solution Approach 1:
The patent applies local quality by creating a permittivity gradient in the molding resin, where the permittivity varies continuously from the center of the through via outward. This is achieved by controlling the filler concentration distribution, with higher filler content near the via center and lower content toward the periphery. This local variation in material properties optimizes both thermal expansion matching and signal transmission by reducing permittivity inhomogeneity effects on radio waves.
Solution Approach 2:
The patent changes the physical parameter of permittivity distribution within the molding resin by controlling filler concentration gradients. Instead of using uniform filler distribution, the filler concentration is varied spatially to create a continuous permittivity gradient. This parameter change transforms the homogeneous resin structure into a functionally graded material that simultaneously achieves thermal compatibility and minimizes signal loss.
2Reliability
If through mold vias are formed in filler-containing resin, then structural support and thermal matching are improved, but signal transmission quality deteriorates due to inhomogeneous permittivity distribution
Solution Approach 1:
The patent implements local quality by establishing a spatially varying filler concentration within the molding resin surrounding the through via. The filler concentration is highest near the via center and decreases radially outward, creating a permittivity gradient. This local differentiation allows the resin to provide structural support and thermal matching while simultaneously minimizing permittivity inhomogeneity effects on passing radio waves.
Solution Approach 2:
The patent uses composite materials by combining molding resin with inorganic fillers in a non-uniform distribution. This creates a functionally graded composite material where the filler concentration varies continuously through the resin thickness. The composite structure maintains the mechanical and thermal benefits of filled resin while reducing electromagnetic interference through the gradient configuration.
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
This configuration effectively suppresses the increase in insertion loss compared to through mold vias without fillers, providing a low-loss through via by trapping radio waves and minimizing scattering, thereby enhancing signal transmission efficiency.
Implementation Method 1
a second insulating film disposed around the first insulating film, the second insulating film having a relative permittivity lower than a relative permittivity of the first insulating film
Data Source
AI summary
A wiring board of an embodiment includes a through via, a first insulating film disposed around the through via, a second insulating film disposed around the first insulating film, a third insulating film disposed around the second insulating film and a resin disposed around the third insulating film. The resin includes fillers. The second insulating film has a relative permittivity lower than a relative permittivity of the first insulating film. The third insulating film has a relative permittivity higher than a relative permittivity of the second insulating film.