BGA Shielding Solder Balls for RF Isolation
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Solution Overview
Problem
Conventional integrated circuit packaging solutions, such as ball grid array (BGA) packages, face challenges in isolating electromagnetic signals effectively, particularly in RF and millimeter wave devices, due to increased complexity and shrinking device sizes, leading to significant electromagnetic signal interference between signal lines.
Innovation Solution
The solution involves surrounding each signal ball in a BGA array with an encircling array of shielding solder balls, forming a 3x3 or 2x2 sub-array, to create a complete shield around the signal ball, thereby confining electromagnetic fields and reducing interference between receive and transmit channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If conventional BGA packaging is used with standard signal line spacing, then device size can be reduced and integration density increased, but electromagnetic signal interference between signal lines increases significantly
Solution Approach 1:
Grounded shielding solder balls are introduced as intermediary elements between signal balls to mediate electromagnetic field interactions. These shielding balls act as mediators that redirect and contain electromagnetic fields, preventing direct interference between adjacent signal lines while maintaining compact device spacing
Solution Approach 2:
The BGA array is segmented into isolated signal paths by inserting grounding shields between signal balls. This segmentation divides the continuous electromagnetic field into discrete, contained regions around each signal ball, preventing field coupling between adjacent signals while maintaining overall device compactness
2Productivity
If signal line spacing is decreased to increase integration density, then more power and signal lines can be connected, but electromagnetic interference between transmit and receive channels worsens
Solution Approach 1:
Grounded shielding solder balls serve as intermediary structures between closely spaced signal lines, enabling high integration density while preventing channel interference. The shields mediate the electromagnetic environment, allowing signals to be routed in close proximity without direct coupling
Solution Approach 2:
The electromagnetic field environment is made non-uniform by strategically placing grounding shields in specific locations between signal paths. This creates localized field containment regions that preserve signal integrity in high-density areas while maintaining overall system performance
3Object-affected harmful factors
If shielding structures are added around signal lines to improve isolation, then electromagnetic interference is reduced, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The same BGA solder ball array structure serves multiple functions: electrical connection, mechanical support, and electromagnetic shielding. The grounding shields are formed using the same reflow soldering process as the signal balls, eliminating the need for separate shielding manufacturing steps and reducing overall device complexity
Solution Approach 2:
The shielding function is merged with the existing BGA interconnect structure. Grounding shields are formed as part of the same solder ball array that provides electrical connections, combining multiple functions into a single integrated structure that simplifies manufacturing while providing effective isolation
4Ease of manufacture
If conventional BGA packaging is used without additional shielding, then manufacturing process remains simple, but insertion loss increases and signal isolation deteriorates
Solution Approach 1:
The solder ball array performs multiple functions including signal transmission, mechanical bonding, and electromagnetic shielding. The grounding shields are created using standard reflow soldering processes already used for BGA assembly, maintaining manufacturing simplicity while reducing insertion loss through improved field containment
Solution Approach 2:
The grounding shields are self-formed during the standard BGA reflow soldering process without requiring additional manufacturing steps. The same thermal and mechanical processes that create the signal balls also form the grounding shields, allowing the structure to shield itself while maintaining ease of manufacture
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
This approach significantly improves signal isolation and reduces insertion loss by controlling the propagation of millimeter wave signals, achieving better than -40 dB isolation and at least 1.0 dB lower insertion loss compared to conventional methods.
Implementation Method 1
surrounding each signal ball with an encircling array of shielding solder balls to thereby improve the isolation between RX (receive) channels and/or TX (transmit) channels
Data Source
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AI summary
A method and apparatus are provided for manufacturing a packaged electronic device (200) which includes a carrier substrate (120) in which conductive interconnect paths (122) extend between first and second opposed surfaces, an integrated circuit die (125) affixed to the first surface of the carrier substrate for electrical connection to the plurality of conductive interconnect paths, and an array of conductors (110), such as BGA, LGA, PGA, C4 bump or flip chip conductors, affixed to the second surface of the carrier substrate for electrical connection to the plurality of conductive interconnect paths, where the array comprising a signal feed ball (112) and an array of shielding ground balls (111) surrounding the signal feed ball.