Antenna Filter Module with Bumper PCB to Prevent CTE Cracking
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Solution Overview
Problem
The increasing number of antennas and RF components in 5G communication systems leads to a larger filter board area and a risk of cracking due to differences in coefficient of thermal expansion (CTE), necessitating a solution to minimize board size and prevent cracks.
Innovation Solution
Implementing a passive circuit on a sub-printed circuit board (PCB) as a bumper between the filter board and RF filter, reducing the filter board area and preventing cracks by using a ceramic waveguide filter with a dielectric medium, and incorporating passive circuits like low-pass filters and couplers on a smaller bumper PCB.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of antennas and RF components is increased to meet 5G communication demands, then communication performance is improved, but the filter board area increases and the risk of cracking due to CTE differences increases
Solution Approach 1:
The invention divides the filter board into a main filter board and a separate bumper PCB. The bumper PCB is specifically designed to couple multiple RF filters while providing thermal expansion compensation. This segmentation allows the system to support more RF components without proportionally increasing the main filter board area, as the bumper PCB handles the filter coupling function separately.
Solution Approach 2:
The bumper PCB is nested between the main filter board and the RF filters, creating a layered structure. This nesting arrangement allows the bumper PCB to serve as an intermediary that couples multiple filters while absorbing thermal expansion stresses, enabling higher component density without directly increasing the main board area.
2Productivity
If the number of antennas and RF components is increased to meet 5G communication demands, then communication performance is improved, but the risk of cracking due to differences in coefficient of thermal expansion (CTE) increases
Solution Approach 1:
The bumper PCB acts as an intermediary component between the main filter board and the RF filters. It has a CTE value designed to be between those of the filter board and the filters, creating a gradual transition that reduces thermal stress concentration. This intermediary structure prevents direct stress transmission that would cause cracking at the filter-board interfaces.
Solution Approach 2:
The invention changes the CTE parameter by selecting specific material compositions for the bumper PCB. The bumper PCB uses a material with CTE of 70-90 ppm/°C, which is intermediate between the filter board (40-60 ppm/°C) and the RF filters (100-150 ppm/°C). This parameter optimization reduces thermal expansion mismatch and prevents cracking under temperature variations.
3Area of stationary object
If a sub-PCB is introduced as a bumper between the filter board and RF filter, then the filter board area is reduced and cracking risk is minimized, but the device structure becomes more complex
Solution Approach 1:
The bumper PCB is designed to perform multiple functions simultaneously: it couples multiple RF filters to the main filter board, provides thermal expansion compensation, reduces the overall filter board area requirement, and minimizes cracking risk. By consolidating these functions into a single component, the invention avoids proportionally increasing device complexity while achieving multiple benefits.
4Area of stationary object
If a sub-PCB is introduced as a bumper between the filter board and RF filter, then the filter board area is reduced, but the device structure becomes more complex
Solution Approach 1:
The bumper PCB introduces a new dimensional layer in the filter assembly structure. Instead of expanding the filter board area in the planar dimension, the invention adds a intermediate layer between the filter board and filters, utilizing the vertical dimension to accommodate the additional component. This dimensional transition allows area reduction while managing complexity through spatial organization.
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
Reduces the filter board area by up to 50% and minimizes signal processing loss, enhancing RF signal processing efficiency and reducing the risk of cracking, while maintaining RF characteristics.
Implementation Method 1
the sub-PCB includes a passive circuit configured to process the RF signal
Implementation Method 2
using a ceramic waveguide filter with a dielectric medium
Implementation Method 3
ceramic waveguide filter with a dielectric medium
Implementation Method 4
differences in coefficient of thermal expansion (CTE), necessitating a solution to minimize board size and prevent cracks
Data Source
AI summary
The disclosure relates to a 5th generation (5G) or pre-5G communication system for supporting a higher data transfer rate than a 4th generation (4G) communication system, such as long-term evolution (LTE). An antenna module is provided. The antenna module includes a filter for filtering a radio frequency (RF) signal, and a sub printed circuit board (PCB), the sub-PCB comprises a passive circuit for processing the RF signal, and, the sub-PCB may be coupled to the filter such that the filter operates as a bumper when being coupled to a filter board.