Leadless Shunt Switch Package for High Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-power shunt switches face challenges with packaged diodes due to 'package parasitics' such as inductance, which reduce isolation, especially at high frequencies, and COB-mounted diodes are costly and prone to damage during assembly.
Innovation Solution
A lead-less package structure featuring a paddle and bond pads aligned in a straight line, with a shunt element wire-bonded to the paddle and encapsulated, providing low parasitics and high isolation by direct contact with the transmission line, similar to chip-on-board design but with added protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If packaged diodes are used, then ease of manufacture and handling are improved, but package parasitics (inductance) increase, reducing isolation performance
Solution Approach 1:
The package structure segments the electrical connection path into distinct functional zones: the paddle provides mechanical support and thermal conduction, while multiple bond pads distributed around the periphery provide electrical connections. This segmentation allows optimization of each zone's function independently, reducing overall parasitics while maintaining manufacturing ease.
Solution Approach 2:
The invention transitions from conventional single-point or two-point connections to a distributed multi-point contact arrangement. By aligning bond pads around the periphery of the paddle and making simultaneous contact with the transmission line, the connection is extended from one dimension (single point) to two dimensions (distributed array), reducing inductance through spatial distribution.
2Reliability
If COB-mounted diodes are used, then isolation performance is improved, but manufacturing cost and damage risk increase
Solution Approach 1:
The encapsulant material is applied beforehand to protect the wire bonds and diode from mechanical damage during assembly and operation. This protective layer prevents the wire bonds from becoming damaged, which is a common issue in COB mounting, thereby reducing rework costs and improving yield without sacrificing the low-parasitic benefits of COB-style mounting.
Solution Approach 2:
The encapsulant serves as an intermediary that provides mechanical protection to the sensitive wire bonds while allowing electrical signals to pass through. This mediator enables the system to achieve both the low parasitics of exposed wire bonds and the protection of packaged components.
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
The solution offers high isolation, ease of assembly, and reduced package parasitics, enhancing performance and cost-effectiveness in high-power shunt switch applications while maintaining impedance and thermal paths.
Implementation Method 1
wire bonded to a top surface of one the bond pads
Implementation Method 2
An encapsulant is disposed on the paddle, the shunt element, the plurality of bond pads, and the wire bond, thereby forming an encapsulated package structure
Implementation Method 3
The package structure is positioned and attached to a transmission line such that the bottom surfaces of each of the at least first subset of bond pads are in simultaneous contact with the transmission line
Data Source
AI summary
A high power shunt switch comprises a leadframe including a paddle for supporting a shunt element, and a plurality of bond pads located around a periphery of the paddle, wherein at least a first subset of the bond pads are aligned in a substantially straight-line configuration. A shunt element is fixedly attached to the paddle and wire bonded to a top surface of one the bond pads. An encapsulant is disposed on the paddle, the shunt element, the plurality of bond pads, and the wire bond, thereby forming an encapsulated package structure. The package structure is positioned and attached to a transmission line such that the bottom surfaces of each of the at least first subset of bond pads are in simultaneous contact with the transmission line. The package structure and the transmission line are fixedly attached to a suitable substrate.