BGA RF Module Pad Arrangement for Impedance Control
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Solution Overview
Problem
The challenge is to downsize optical communication modules while maintaining impedance and preventing signal quality deterioration, which is hindered by the limitations of conventional techniques in reducing the size of BGA radio frequency module pads and solder balls.
Innovation Solution
The proposed solution involves a BGA radio frequency module with a unique arrangement where the distance between signal pads and adjacent ground pads is shorter than the distance to other ground pads, and a PCB structure with reduced ground plane areas, which helps in maintaining longer distances between signal pads and ground pads, thereby suppressing impedance lowering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If pads and solder balls are downsized to reduce module size, then the area of the BGA radio frequency module is reduced, but impedance between pads and solder balls lowers causing signal quality deterioration
Solution Approach 1:
The patent applies local quality by creating different pad arrangement patterns in different regions of the BGA module. Signal pads are arranged with specific spacing from ground pads in certain areas, while other areas have different configurations. This localized differentiation allows impedance control in critical signal areas while maintaining compact overall dimensions.
Solution Approach 2:
The patent employs asymmetry by using non-uniform pad arrangements where the distance between signal pads and adjacent ground pads is intentionally made shorter than the distance to other ground pads. This asymmetric configuration creates specific impedance characteristics in signal paths while allowing flexible overall module sizing.
2Ease of manufacture
If pads are arranged at equal intervals to simplify manufacturing, then ease of manufacture is improved, but impedance control and signal quality are compromised
Solution Approach 1:
The patent transitions from uniform pad arrangement to localized differentiation where signal pads have specific distance relationships with adjacent ground pads compared to other ground pads. This local quality variation enables impedance control while maintaining a relatively simple manufacturing process by only requiring precise control in specific critical areas rather than the entire pad array.
Data Source
AI summary
Provided are a BGA radio frequency module, a substrate for a BGA radio frequency module, and an optical communication module, wherein realize downsizing of an optical communication module without lowering impedance between a pad and a solder ball. The BGA radio frequency module according to the present disclosure includes a differential signal pair including a first signal pad and a second signal pad, a first ground pad disposed adjacent to the first signal pad, a second ground pad disposed adjacent to the second signal pad, at least one third ground pad disposed at a position spaced from the first signal pad more than a distance between the first signal pad and the first ground pad, and at least one fourth ground pad disposed at a position spaced from the second signal pad more than a distance between the second signal pad and the second ground pad.