Stacked RF Circuit Module With Flip-Chip Links for Low Signal Loss
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Solution Overview
Problem
Existing RF circuit modules face challenges in reducing size while maintaining effective heat radiation and minimizing signal loss due to large component footprints and long wire connections, which lead to impedance mismatching and reduced heat dissipation efficiency.
Innovation Solution
The RF circuit module employs a flip-chip bonding technique between substrates, eliminating the need for wire bonding by directly connecting conductor layers between a control circuit and a radio-frequency amplifier circuit on separate substrates, thereby reducing module size and enhancing heat radiation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If components are individually mounted on the module substrate, then the module can be assembled, but the footprint is large and wire connections are long causing signal loss
Solution Approach 1:
The patent merges the module substrate function with the component mounting substrate. The radio-frequency amplifier substrate serves dual purposes: as the component carrier and as the module substrate, eliminating the need for separate module substrate and reducing wire connections to external electrodes.
Solution Approach 2:
The patent transitions from a planar arrangement where components are mounted on the surface to a three-dimensional stacked arrangement where substrates are laminated vertically. This reduces the horizontal footprint and shortens connection paths by utilizing the vertical dimension for signal transmission.
2Area of stationary object
If the module size is reduced by laminating substrates, then the footprint is smaller, but space for wire bonding is needed and parasitic inductance increases
Solution Approach 1:
The patent extracts and eliminates the wire bonding process entirely. Instead of using wires to connect the radio-frequency amplifier to external electrodes, the amplifier output is directly connected to external electrodes through conductor layers on the amplifier substrate, removing the source of parasitic inductance.
Solution Approach 2:
The patent introduces conductor layers as intermediaries between the amplifier circuit and external electrodes. These conductor layers provide direct electrical connection paths without requiring wire bonds, thereby reducing parasitic inductance while enabling compact laminate structure.
3Reliability
If GaAs substrate is used for radio-frequency amplifier, then high frequency performance is achieved, but heat radiation property is low
Solution Approach 1:
The patent segments the thermal management function from the radio-frequency amplification function. The GaAs substrate is dedicated to RF performance while a separate substrate (silicon or ceramic) provides heat radiation, allowing each material to optimize its specialized function without compromise.
Solution Approach 2:
The patent introduces an intermediary substrate between the GaAs amplifier and the external environment. This intermediate substrate acts as a heat sink that conducts heat away from the GaAs device, enabling effective thermal management while preserving the GaAs substrate's RF performance characteristics.
4Reliability
If wire bonding is used to connect components, then electrical connections are established, but connection length is long causing signal loss
Solution Approach 1:
The patent replaces the mechanical wire bonding system with a planar conductor layer system. Instead of using three-dimensional wire connections that require bending and routing, the connection is achieved through two-dimensional conductor traces on the substrate, dramatically reducing connection length and parasitic effects.
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 approach allows for a compact RF circuit module with improved heat dissipation and reduced signal loss, achieving high radio-frequency performance and efficient heat radiation without compromising size constraints.
Implementation Method 1
The first substrate is flip-chip bonded to the module substrate
Implementation Method 2
enhancing heat radiation efficiency
Data Source
AI summary
An RF circuit module includes a module substrate, a first substrate in which a first circuit is implemented, and a second substrate in which a second circuit is implemented. The first circuit includes a control circuit that controls an operation of the second circuit. The second circuit includes a radio-frequency amplifier circuit that amplifies an RF signal. The second substrate is mounted on the first substrate. The first substrate is disposed on the module substrate such that a circuit forming surface faces the module substrate. The first substrate and the second substrate have a circuit-to-circuit connection wire that electrically connects the first circuit and the second circuit without intervening the module substrate.