Stacked Spiral Coil Multilayer Substrate for Surface Flatness
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Solution Overview
Problem
Conventional multilayer substrates with planar coils exhibit significant unevenness on their principal surfaces due to the thickness difference between overlapping and non-overlapping areas of plated wirings, leading to manufacturing challenges and performance issues.
Innovation Solution
A multilayer substrate design featuring a first and second coil pattern with specific spiral shapes and thickness profiles, where the second coil pattern has a smaller maximum thickness and is positioned to overlap or be between the first coil pattern, with a manufacturing method involving electroplating and patterning of metal films on insulating layers to minimize surface unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wirings are formed by plating with great thickness, then electrical conductivity is improved, but surface unevenness increases
Solution Approach 1:
The patent transitions from two-dimensional planar overlapping coil patterns to three-dimensional stacked coil patterns on different insulating layers. By positioning coil patterns on separate layers (first insulating layer and second insulating layer) rather than overlapping them in the same plane, the design eliminates thickness accumulation while maintaining electrical conductivity through vertical stacking and via-hole connections.
2Area of stationary object
If coil patterns are positioned to overlap to save space, then area utilization is improved, but surface unevenness increases
Solution Approach 1:
The patent resolves the space utilization versus flatness contradiction by moving coil patterns from horizontal overlap in 2D to vertical stacking in 3D. Multiple coil patterns are arranged on different insulating layers (first and second insulating layers) and connected through via holes, achieving high area utilization without surface unevenness.
Solution Approach 2:
The patent implements a nested structure where multiple coil patterns are embedded within different insulating layers. The first coil pattern is embedded in the first insulating layer, the second coil pattern in the second insulating layer, with via holes providing vertical connectivity between layers, creating a compact three-dimensional integrated structure.
3Reliability
If multiple thick plated wirings are stacked, then inductance value is improved, but surface unevenness increases
Solution Approach 1:
The patent achieves high inductance values without thick plated wirings by stacking multiple thin coil patterns on different insulating layers. The first coil pattern on the first insulating layer and the second coil pattern on the second insulating layer are connected through via holes, creating a multi-layer inductive structure that maintains surface flatness while achieving the desired inductance.
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 reduces or prevents surface unevenness, allowing for the creation of substrates with improved flatness and reduced conductor loss, while maintaining desired inductance values and electrical connectivity.
Implementation Method 1
a plated layer grown by electroplating
Data Source
AI summary
A multilayer substrate includes first and second insulating layers stacked in a stacking direction with the second insulating layer located at a first side of the first insulating layer in the stacking direction, a first coil pattern disposed on a first principal surface of the first insulating layer on the first side of the first insulating layer in the stacking direction, and a second coil pattern disposed on a first principal surface of the second insulating layer on the first side of the second insulating layer in the stacking direction. The first and second coil patterns have spiral shapes. When viewed from the layer stacking direction, at least a portion of a first area in which the first coil pattern is disposed and at least a portion of a second area in which the second coil pattern is disposed overlap each other.