Millimeter-Wave Chip Packaging With GSG Pillars for Channel Isolation
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Solution Overview
Problem
Millimeter-wave chip packaging faces challenges with excessive signal loss and distortion due to physical proximity between channels, leading to inter-channel interference, especially during simultaneous transmission and reception of millimeter-wave signals.
Innovation Solution
The system employs a substrate with a top and bottom metal layer separated by an insulation layer, featuring a ground-signal-ground (GSG) pillar structure and coplanar waveguide (CPW) structures to ensure smooth signal transition and multi-channel isolation, utilizing materials with low dielectric loss and strategically positioned ground planes to minimize interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple channels of millimeter-wave signals are transmitted simultaneously through closely spaced channels, then signal transmission capacity is improved, but inter-channel interference increases due to substrate leakage and spatial radiation
Solution Approach 1:
The patent introduces ground shielding structures as intermediary elements between adjacent signal channels. These ground planes act as mediators that redirect electromagnetic fields, preventing substrate leakage and spatial radiation from one channel from interfering with adjacent channels, thereby enabling high-capacity multi-channel transmission without interference
Solution Approach 2:
The patent applies different structural configurations to different regions of the chip packaging system. Specifically, ground shielding structures are selectively positioned between channels that require isolation, while maintaining open configurations where needed. This localized application of shielding provides targeted interference prevention without compromising overall signal transmission capacity
2Ease of manufacture
If conventional chip packaging structures are used for millimeter-wave signals, then manufacturing simplicity is maintained, but excessive signal loss and distortion occur
Solution Approach 1:
The patent modifies key parameters of the packaging structure, including the characteristic impedance of transmission lines (set to 50 ohms to match standard RF interfaces), the spacing and positioning of ground shielding structures, and the dielectric properties of the substrate. These parameter optimizations enable millimeter-wave signals to maintain their integrity while using conventional manufacturing processes
Solution Approach 2:
The patent implements ground planes and grounding structures that create equipotential regions throughout the packaging system. By establishing uniform reference potentials through properly grounded structures, the patent eliminates potential differences that would otherwise cause signal distortion and loss, thereby improving signal transmission quality without complicating manufacturing
3Object-generated harmful factors
If ground shielding structures are added between signal channels, then channel isolation is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple functions into the ground shielding structures. These structures simultaneously serve as electromagnetic shields, reference planes for impedance control, and mechanical support elements. By merging these functions into a single integrated structure, the patent achieves effective channel isolation without proportionally increasing device complexity
Solution Approach 2:
The ground planes and shielding structures are designed to perform multiple functions: providing electromagnetic shielding between channels, establishing reference potentials for signal integrity, supporting the mechanical structure, and facilitating thermal management. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity while achieving superior channel isolation
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 significantly reduces signal distortion and loss, achieving efficient millimeter-wave signal transmission and effective channel isolation, as demonstrated by simulations showing minimal RF signal loss across a wide frequency spectrum.
Implementation Method 1
Characteristic impedance of the GSG pillar structure may be set at a desired value for smooth millimeter wave signal transition
Implementation Method 2
The chip also comprises a second ground plane positioned above the first signal path. The second ground plane electrically connects the first ground plane via a plurality of on-chip metal-to-metal vias. With the second ground plane, the first CPW structure becomes a coplanar waveguide with ground (CPWG) structure, which provides enhanced isolation of the first signal path within the chip
Implementation Method 3
Materials with low dielectric loss may be chosen for the insulation layer for better high frequency performance
Data Source
AI summary
Various system embodiments for millimeter-wave chip packaging are disclosed in the present disclosure for smooth millimeter wave signal transition and good multi-channel signal isolation. The chip packaging features a substrate and a chip electrically connected using a plurality of metal pillars. A signal pillar and surrounding metal pillar may form a ground-signal-ground (GSG) pillar structure. A chip coplanar waveguide (CPW) structure may be formed on the chip around a signal path. A substrate CPW structure may also be form around a signal strip, which is electrically connected to the signal path. Characteristic impedances of the GSG pillar structure, the chip CPW structure and the substrate CPW structure may be within a predetermined range of each other to ensure smooth millimeter wave signal transition with minimum signal loss or distortion.