RF Interconnect Riser Layout for Shorter High-Frequency Wire Bonds
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Solution Overview
Problem
In high-frequency applications, traditional wire bonding techniques result in long wire bonds that lead to increased inductance and crosstalk, making it challenging to achieve efficient data transfer and signal integrity in devices like Mach-Zehnder modulators and Intradyne Coherent Receiver chips.
Innovation Solution
An RF interconnect configuration using a riser with integrated through riser vias is employed to raise the RF interconnect towards the surface mount device, allowing for shorter wire bonds and reducing inductance, thereby improving signal integrity and channel isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional wire bonding is used to electrically couple devices to substrate, then electrical connection is achieved, but wire bond length increases leading to increased inductance and crosstalk
Solution Approach 1:
The patent introduces a vertical dimension by adding a riser structure that raises the RF interconnect from the substrate plane to meet the surface mount device. This dimensional change transforms the wire bond path from a long horizontal connection to a short vertical connection, significantly reducing wire bond length and associated inductance while maintaining electrical connectivity.
Solution Approach 2:
The riser acts as an intermediary component between the substrate and the surface mount device. It provides a raised platform that brings the RF interconnect closer to the device, enabling shorter wire bonds. The riser includes through-riser vias that facilitate the electrical connection while maintaining the height adjustment function.
2Reliability
If wire bond length is reduced for high-frequency operations, then inductance and crosstalk are reduced, but additional structural components are required
Solution Approach 1:
The riser structure serves multiple functions simultaneously: it raises the RF interconnect to reduce wire bond length, provides mechanical support for the connection, and includes integrated through-riser vias for electrical connectivity. This multi-functionality reduces the need for separate components and minimizes overall device complexity despite the added vertical structure.
3Productivity
If RF interconnect is raised towards surface mount device, then wire bond length is minimized, but additional manufacturing steps are required
Solution Approach 1:
The riser structure is pre-formed with integrated through-riser vias before being mounted on the substrate. This preliminary preparation of the vertical interconnect structure with built-in electrical pathways simplifies the overall manufacturing process by eliminating the need for complex post-assembly routing and connection steps.
Data Source
AI summary
Aspects of the subject disclosure may include, for example, system, comprising a substrate having an interconnect in or on a surface of the substrate, a riser disposed over the surface, the riser being configured with one or more through riser vias for coupling to the interconnect, a device positioned over the surface, the device having one or more conductive contacts residing in a plane of the device, and one or more wire bonds coupling the one or more through riser vias with the one or more conductive contacts thereby enabling connectivity of the interconnect to be raised toward or to the plane of the device such that at least one of the one or more wire bonds has a limited physical length. Other embodiments are disclosed.