Stacked VRM Layout With Recessed BGA Clearance for Underfill
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Solution Overview
Problem
Existing voltage regulating modules (VRMs) face challenges in high packing density due to inflexible design, leading to manufacturing difficulties and reduced ASIC performance, as they struggle to allocate space for active and passive components, fasteners, and underfill within the module.
Innovation Solution
A VRM design featuring recessed areas on the bottom ball grid array (BGA) attaching layer, allowing for increased clearance and preventing underfill clogging, while maintaining internal layer space and packing density, includes a first layer with passive components and a second layer with active components, and a third layer for current multiplication, enabling efficient power delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If VRMs are designed with high packing density, then area utilization is improved, but manufacturing difficulty increases due to space allocation challenges for components and fasteners
Solution Approach 1:
The patent transitions from a two-dimensional planar layout to a three-dimensional stacked architecture with multiple layers (first layer, second layer, third layer). This vertical dimensionality change allows components to be arranged in stacked configurations, significantly improving area utilization while providing sufficient space for both active/passive components and fasteners without increasing manufacturing complexity
Solution Approach 2:
The VRM is segmented into multiple functional layers: a first layer for passive components, a second layer for active components, and a third layer for current multiplication. This segmentation allows each layer to be optimized independently for its specific function, facilitating manufacturing while achieving high packing density through vertical integration
2Ease of operation
If recessed areas are added to prevent underfill clogging, then underfill flow is improved, but device complexity increases
Solution Approach 1:
Recessed areas are introduced only at specific locations where the ball grid array (BGA) attaches to the first layer, rather than throughout the entire device. This localized modification prevents underfill clogging at critical interfaces while maintaining the overall simplicity of the VRM structure and minimizing additional device complexity
3Reliability
If space is allocated for fasteners and underfill, then reliability is improved, but packing density decreases
Solution Approach 1:
The patent resolves the space conflict by utilizing the vertical dimension through multi-layer stacking. Fasteners and underfill clearance are accommodated in the vertical space between layers and at layer interfaces, while the horizontal footprint remains maximized for component packing. This allows both reliability requirements and high packing density to be achieved simultaneously
Data Source
AI summary
A voltage regulating module design is provided. In one aspect, a voltage regulating module (VRM) includes a first layer configured to output a regulated voltage that is based on a stepped down voltage, and a second layer stacked with the first layer, and a plurality of contacts, such as a ball grid array (BGA), on the first layer. The second layer includes a plurality of active components configured to provide the stepped down voltage to the first layer. The first and second layers have overlapping recesses, and the recess of the first layer has a larger footprint than the recess of the second layer. A plurality of the VRMS can be arranged to form an opening including a counterbore. A faster, such as a bolt, can be positioned in the opening. The first layer can have a larger clearance from the fastener positioned in the opening than the second layer.