Tie Bar Resonance Suppression in Flat No Lead Packages
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Solution Overview
Problem
Flat no lead packages in microwave products suffer from tie-bar resonances that cause increased leakage and sharp dips in gain due to their inability to be removed after manufacturing, leading to significant signal interference and performance issues.
Innovation Solution
An electronic circuit design that incorporates a grounding network connected to the tie-bars, which dampens or re-routes tie-bar resonances by utilizing lossy components such as resistors, inductors, capacitors, and transmission lines to reduce the Q-value and move resonant frequencies to non-significant ranges, thereby suppressing tie-bar resonance effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tie-bars are used in flat no lead packages during manufacturing, then the package structure is maintained and leads are connected, but tie-bar resonances cause increased signal leakage and sharp dips in gain
Solution Approach 1:
A grounding network is introduced as an intermediary between the tie-bar and the ground plane. This grounding network acts as a mediator that provides an alternative current path, preventing the tie-bar from resonating and thereby eliminating the harmful electromagnetic effects while maintaining the structural integrity of the package
2Ease of manufacture
If tie-bars protrude beyond the central plate to overlap the ground plane, then manufacturing connections are established, but resonant stub effects are created at λ/4, 3λ/4, 5λ/4 frequencies
Solution Approach 1:
The grounding network converts the harmful resonant stub effect into a beneficial grounded structure. By providing a controlled impedance path to ground, the previously harmful protruding tie-bar structure is transformed into a useful element that can be deliberately designed to achieve desired electrical characteristics while eliminating the unwanted resonance
3Reliability
If the grounding network is made lossy with resistors, inductors, and capacitors, then resonance dampening is achieved, but additional components increase device complexity
Solution Approach 1:
The grounding network utilizes components with specific parameter values designed to create the desired impedance characteristics at the resonant frequencies. By carefully selecting the values of resistors, inductors, and capacitors, the network achieves effective resonance dampening while maintaining a relatively simple structure that can be integrated into the existing package design
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 grounding network effectively dampens tie-bar resonances, reducing signal leakage and stabilizing device gain by introducing losses that minimize the impact of tie-bar resonances, improving the overall performance of flat no lead packages.
Implementation Method 1
Tie-bar resonances can lead to a number of problems. They can, for example, create increased leakage from one I/O-port to another
Implementation Method 2
By means of the grounding network, the resonances caused by the protrusion or protrusions, e.g. in the form of tie-bars, can be dampened to a high degree
Implementation Method 3
The resonances' behavior is highly dependent on the impedance loading created by the grounding network, which is frequency dependent, and which can thus be designed to move the resonances to a desired frequency
Implementation Method 4
Losses in the grounding network can be generated in different ways: they can be due to conductor losses or dielectric losses, and in some cases radiation losses
Implementation Method 5
Losses in the grounding network can be generated in different ways: they can be due to conductor losses or dielectric losses
Data Source
AI summary
An electronic circuit (200, 300, 400, 500) which comprises a flat circuit board with a layer of a non-conducting material with opposing first and second main surfaces, with a central ground pad arranged on a part of the first main surface and a ground plane arranged on the second main surface which protrudes beyond the central ground pad. There is a flat no leads package (100) arranged on the central ground pad. The flat no leads package (100) comprises a central plate (105) with protrusions (110, 120, 130, 140) which protrude beyond the central ground pad and overlap the ground plane (210). The electronic circuit (200, 300, 400, 500) comprises a grounding network (235, 240, 245, 230; 405, 435; 535, 545) connected to the ground plane (213) and to at least one protrusion (110, 120, 130, 140), thereby connecting the at least one protrusion (110, 120, 130, 140) electrically to the ground plane (210).