Contactless Waveguide Transition Packaging for Low-Loss MMIC Links
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Solution Overview
Problem
Conventional packaging technologies for high-frequency applications, such as wire-bonding and flip-chip packaging, face challenges including high insertion losses, impedance mismatch, and mechanical reliability issues due to bond-wire inductance, radiation, and thermal expansion mismatches, which limit bandwidth and increase manufacturing complexity.
Innovation Solution
A packaging structure with a waveguide split-block assembly and high impedance surface, featuring a periodic or quasi-periodic structure of pins, which prevents leakage of waveguide modes into the circuit cavity, eliminating the need for bond-wires or flip-chip connections by using a contactless transition with a gap waveguide design that blocks undesired wave propagation while allowing RF power transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire-bonding is used for chip-to-chip interconnects, then mechanical connection is achieved, but bond-wire inductance causes impedance mismatch and radiation losses at high frequencies
Solution Approach 1:
The patent replaces the mechanical wire-bonding system with a contactless electromagnetic coupling system. The mechanical connection is substituted by electromagnetic field coupling between the waveguide and circuit cavity, eliminating bond-wires and their associated inductance and radiation losses while maintaining reliable signal transmission at high frequencies
Solution Approach 2:
The patent introduces a waveguide-circuit cavity transition structure as an intermediary between the chip and external connections. This transition structure provides the necessary electromagnetic mode conversion while eliminating the need for bond-wires, thereby reducing insertion loss and improving high-frequency performance
2Reliability
If a separate probe transition is used to interface waveguide and circuit, then mode conversion is achieved, but the transition must be sufficiently narrow to prevent leakage which complicates the packaging process
Solution Approach 1:
The patent merges the waveguide transition and circuit cavity into a single integrated packaging structure. The waveguide, transition region, and circuit cavity are combined as one unified component, eliminating the need for separate probe transitions and their associated alignment and mounting complexities while maintaining effective mode conversion
3Reliability
If bond-wires are used for chip-to-chip interconnects, then electrical connection is achieved, but wire inductance limits bandwidth especially above 70 GHz
Solution Approach 1:
The patent replaces the inductive wire-bonding system with a contactless electromagnetic coupling system that operates effectively at high frequencies. The electromagnetic field coupling eliminates the bandwidth limitations imposed by wire inductance, enabling operation above 70 GHz while maintaining reliable electrical connection through field coupling rather than physical conductors
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 solution provides a robust, wideband packaging structure with low insertion losses, improved mechanical reliability, and enhanced RF performance, suitable for frequencies above 67 GHz, reducing parasitic effects and thermal stresses, and facilitating easy assembly and measurement accuracy.
Implementation Method 1
The split-block assembly is provided with a periodic or quasi-periodic structure of pins, which forms a high impedance surface
Implementation Method 2
The narrow gap between the high impedance surface and the transition region allows RF power transmission while blocking undesired wave propagation
Implementation Method 3
The microstrip line at an end is provided with a coupling section for coupling electromagnetic fields from the microstrip line to the waveguide in the transition
Data Source
AI summary
The present invention relates to a packaging structure (100)comprising a split-block assembly with a first and a second conducting block section (10A,20A) and at least one transition between a first planar transmission line (2A) and a second transmission line (11A), and one or more input/output ports. The first transmission line (2A) is arranged on a substrate, e.g. an MMIC (1A), disposed on the first conducting block section (10A) and comprises a coupling section (3A), the first conducting block (10A) comprises a cavity (4A) with a cavity opening in an upper surface of the first conducting block section (10A) so arranged that,in an assembled state of the split-block assembly,the coupling section (3A) will be located above, or in,the opening of the cavity (4A), the second transmission line (11A) being in line with the first transmission line (2A) and located on an opposite side of the opening of the cavity (4A).The second conducting block section (20A) acts as a lid in an assembled state of the packaging structure. One of the conducting block sections is provided with a high impedance surface (15A)in a transition region along or facing the first (2A) and second (11A) transmission lines, a narrow gap being provided between the high impedance surface region (15A) and the opposing surface of the other conducting block section (10A)at least in the transition region such that the transition will be contactless without any galvanic contact between the first and second transmission lines(2A,11A).