Interposer Circuit Thermal Isolation and Impedance Control
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Solution Overview
Problem
Existing optoelectronic modules face challenges with high data rate performance due to limitations in wire bonds and ceramic circuits, including rigid alignment requirements, impedance constraints, thermal isolation issues, and high costs, especially at data rates above 28 gigabits per second.
Innovation Solution
The use of interposer circuits, such as flex circuits, to electrically couple integrated circuits (ICs) to electrical interconnects, eliminating the need for wire bonds and ceramic shims, allowing for flexible impedance, improved thermal isolation, and reduced costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If wire bonds and ceramic circuits are used to electrically couple ICs to electrical interconnects, then electrical connection is achieved, but thermal isolation is poor and power consumption is high
Solution Approach 1:
An interposer circuit is introduced as an intermediary component between the IC and electrical interconnects. The interposer provides thermal isolation through its material composition and structure, reducing heat transfer from the IC to surrounding components while maintaining electrical connectivity through controlled impedance traces.
Solution Approach 2:
The interposer circuit utilizes thin film structures and flexible circuit board materials to achieve thermal isolation. The thin film nature of the interposer allows it to act as a thermal barrier while maintaining electrical functionality, reducing power consumption associated with thermal management.
2Reliability
If wire bonds and ceramic shims are used for electrical coupling, then electrical connection is established, but device cost is high
Solution Approach 1:
The interposer circuit replaces expensive wire bonds and ceramic shims with a more cost-effective flexible circuit board structure. While the interposer itself is a dedicated component, its manufacturing cost is significantly lower than traditional wire bond and ceramic shim assemblies, achieving cost reduction while maintaining reliable electrical connection.
Solution Approach 2:
The invention changes the physical and electrical parameters of the coupling structure by transitioning from rigid wire bonds and ceramic shims to flexible circuit traces with controlled impedance. This parameter change enables cost-effective manufacturing through standard flexible PCB processes while maintaining electrical connection reliability through precise impedance control.
3Reliability
If rigid ceramic circuits are used for electrical coupling, then electrical connection is achieved, but impedance flexibility is constrained
Solution Approach 1:
The interposer circuit introduces dynamic flexibility in impedance design through its flexible circuit board construction. The trace geometry, width, and routing can be dynamically adjusted during the PCB design process to achieve various impedance values and profiles, unlike rigid ceramic circuits with fixed impedance characteristics.
Solution Approach 2:
The flexible circuit board material and trace structure enable continuous adjustment of electrical parameters including impedance, capacitance, and inductance. This parameter flexibility allows the interposer to be adapted to different electrical requirements without changing the fundamental structure, providing versatility while maintaining reliable electrical connection.
4Reliability
If wire bonds are used to connect ICs to RF interconnects, then electrical connection is established, but alignment requirements are rigid and complex
Solution Approach 1:
The interposer circuit transitions the connection from a point-to-point wire bond approach to a planar trace-based connection. This dimensional change from three-dimensional wire routing to two-dimensional PCB trace routing simplifies alignment requirements, as the flexible circuit board can accommodate variations in positioning through its flexible nature and standard mounting tolerances.
Solution Approach 2:
The interposer serves as an intermediary that absorbs alignment tolerances between the IC and electrical interconnects. The flexible circuit board material and trace routing provide mechanical compliance that compensates for positioning variations, eliminating the need for rigid precision alignment required by wire bonds while maintaining reliable electrical connection.
Data Source
AI summary
In an example, a communication module such as an optoelectronic communication module may include an integrated circuit (IC), an electrical interconnect, and an interposer circuit. The electrical interconnect may include a radio frequency (RF) interconnect or a direct current (DC) interconnect. The interposer circuit may be electrically coupled between the IC and the electrical interconnect.