RF Monoblock Filter Bracket for Thermal Stress Relief
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Solution Overview
Problem
Ceramic monoblock filters mounted on printed circuit board assemblies are prone to cracking or damage due to thermal and vibration stresses, which can affect the solder joints and the ceramic material.
Innovation Solution
A bracket system comprising a plate with fingers that are secured to the RF filter and printed circuit board, providing stress relief and mechanical stability by being soldered to the substrate, thereby reducing the risk of cracking and damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ceramic monoblock filters are mounted and soldered directly to printed circuit board assemblies, then the filter can be securely attached and electrically connected, but the filter becomes susceptible to cracking or damage from thermal and vibration stresses
Solution Approach 1:
A bracket made of stress-relief material is introduced as an intermediary component between the ceramic filter and the PCB assembly. This bracket absorbs and isolates thermal and vibration stresses, preventing them from being transmitted to the filter. The bracket includes a first portion that contacts the filter and a second portion that contacts the PCB, with a stress-relief section that flexes to accommodate differential expansion and vibration, thereby maintaining reliable attachment while protecting filter integrity.
2Stability of the object's composition
If the filter is rigidly secured to the PCB assembly, then mechanical stability is improved, but thermal stresses from temperature changes cause cracking or damage to the filter or solder joints
Solution Approach 1:
The bracket is designed with a stress-relief section that changes its physical parameters (flexibility, expansion coefficient) to accommodate thermal stress. This section is made of a material or structure that can flex and expand differently from both the filter and PCB, allowing it to absorb thermal expansion differences and prevent stress transmission that would cause cracking.
3Ease of manufacture
If the filter is directly soldered to the PCB, then the assembly process is simple and direct, but vibration stresses increase the risk of damage to solder joints or ceramic material
Solution Approach 1:
The mounting structure is segmented into three distinct portions: a first portion that contacts the filter, a second portion that contacts the PCB, and a stress-relief section connecting them. This segmentation allows each portion to be optimized for its specific function while maintaining ease of assembly. The bracket can be attached to the filter and PCB separately, with the stress-relief section providing vibration isolation without complicating the manufacturing process.
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 bracket system effectively minimizes the risk of cracking or damage to the filter and printed circuit board assembly by distributing thermal and mechanical stresses, enhancing mechanical stability and preventing separation during vibrations or G-force applications.
Implementation Method 1
The bracket system effectively minimizes the risk of cracking or damage to the filter and printed circuit board assembly by distributing thermal and mechanical stresses
Implementation Method 2
the fingers of the plate are soldered to the surface of the substrate
Data Source
AI summary
A combination RF filter and printed circuit board assembly wherein the RF filter is defined by a block of dielectric material including at least first and second side surfaces. A metal bracket with a plurality of fingers is secured to each of the first and second side surfaces. The fingers on the brackets extend through respective apertures in the printed circuit board and are soldered to the printed circuit board. The brackets relieve and transfer the thermal and mechanical stresses that result from use of a filter and printed circuit board that are made of materials with different thermal and mechanical characteristics and reduce the risk of cracking or damage to the filter, the printed circuit board, and the solder joints during use.