Wafer Level Inductor Using Solder Ball Windings
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Inductors in IC packages face limitations in supporting high current due to size constraints, resulting in high resistance and low quality factor, and removing solder balls to improve inductance compromises structural stability.
Innovation Solution
A high quality factor inductor design is implemented in wafer level packaging, utilizing multiple metal layers and solder balls to create a winding with increased turns, leveraging the height of solder balls to enhance inductance and reduce resistance, while maintaining structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder balls are removed near the inductor to improve inductance and Q factor, then inductance performance is improved, but structural stability of the packaging substrate deteriorates
Solution Approach 1:
The patent extracts the harmful effect of solder balls on inductor performance by removing them from specific regions near the inductor windings, while retaining them in other regions to maintain structural stability. This selective removal allows the inductor to operate without magnetic flux disruption from nearby solder balls, improving Q factor and inductance performance.
Solution Approach 2:
The patent applies different configurations of solder balls in different regions of the packaging substrate. Specifically, solder balls are removed from regions adjacent to the inductor windings where they would disrupt magnetic flux, while solder balls are retained in other regions to provide mechanical support and structural stability to the packaging substrate and PCB assembly.
2Power
If inductor size is increased to support high current, then current capability is improved, but available real estate in IC package is exhausted
Solution Approach 1:
The patent transitions the inductor design from a planar two-dimensional layout to a three-dimensional structure by utilizing multiple metal layers stacked vertically. The inductor comprises first and second metal layers with windings that extend through the vertical dimension, connected by vias. This vertical stacking allows the inductor to achieve higher current capability and inductance values without increasing the horizontal footprint on the packaging substrate, effectively using the third dimension to resolve the space constraint.
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 achieves better inductance, lower resistance, and higher quality factor, enabling support for high current applications without sacrificing structural stability.
Implementation Method 1
The first metal layer of the PCB, the set of solder balls, the second and third metal layers of the die are configured to operate as an inductor having a winding with a number, N, of turns that is 2 or more
Implementation Method 2
leveraging the height of solder balls to enhance inductance and reduce resistance, while maintaining structural stability
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Some novel features pertain to a first example provides a semiconductor device that includes a printed circuit board (PCB), asset of solder balls and a die. The PCB includes a first metal layer. The set of solder balls is coupled to the PCB. The die is coupled to the PCB through the set of solder balls. The die includes a second metal layer and a third metal layer. The first metal layer of the PCB, the set of solder balls, the second and third metal layers of the die are configured to operate as an inductor in the semiconductor device. In some implementations, the die further includes a passivation layer. The passivation layer is positioned between the second metal layer and the third metal layer. In some implementations, the second metal layer is positioned between the passivation layer and the set of solder balls.