Dual Footprint Surface Mount Power Module with Castellated Edge Pads
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Solution Overview
Problem
The existing surface mount power module packaging technologies, such as through-hole mounting and peripheral leaded designs, increase manufacturing costs and complexity due to the need for specialized tools and equipment, and pose challenges in inspection and rework, especially when using stand-off components to facilitate visual inspection, which also raises the overall height and material costs.
Innovation Solution
A dual footprint mounting package for surface mount power converter modules is introduced, where copper etch is extended to the edge of the PCB, and edge pads are created using a castellation feature, allowing for both standard SMT pads and edge pads to be used, with a solder barrier to prevent solder flow between them, enhancing mechanical integrity and facilitating inspection and rework.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If through-hole mounting technology is used for power converter modules, then mechanical connection reliability is improved, but manufacturing complexity and cost increase due to additional manufacturing steps
Solution Approach 1:
The patent merges the mounting function into the existing SMT process by integrating pad extensions directly onto the PCB surface. The power converter module uses standard SMT packaging with extended pads that connect directly to the PCB without requiring separate through-hole mounting operations, thereby combining mechanical connection and electrical connection into a single SMT process step.
Solution Approach 2:
The extended pad design serves multiple functions: it provides both the electrical connection interface and the mechanical attachment surface for the power converter module. The same pad structure that conducts electrical current also serves as the mounting surface, eliminating the need for separate mounting hardware or processes.
2Productivity
If peripheral leaded power converter modules are used, then manufacturing steps are reduced, but the occupied space on PCB increases
Solution Approach 1:
The patent transitions from a two-dimensional surface mount configuration to a three-dimensional solution by extending pads vertically from the PCB surface. The extended pads rise above the PCB surface to provide the necessary connection interface, allowing the power converter module to be mounted with its leads connecting to these vertical extensions rather than requiring lateral space on the PCB.
3Area of stationary object
If leads are moved beneath the power converter module, then occupied space on PCB is reduced, but inspection and rework difficulty increase
Solution Approach 1:
The patent segments the connection interface into distinct visible portions. The extended pads are designed to extend above the PCB surface to a height that is visually distinguishable, creating a segmented structure where the connection points are separated from the PCB surface. This segmentation allows inspection tools to access and detect the connection quality without requiring disassembly or specialized equipment.
4Difficulty of detecting and measuring
If stand-off components are added to facilitate visual inspection, then inspection ease is improved, but overall device height and material cost increase
Solution Approach 1:
The extended pads serve their own inspection function without requiring additional stand-off components. The pads are designed to extend sufficiently above the PCB surface to be directly visible and accessible to inspection tools, allowing the connection interface to self-indicate its status. This self-service approach eliminates the need for separate inspection aids while maintaining adequate inspection accessibility.
Data Source
AI summary
A dual footprint mounting package for a surface mount power converter modules and its method of manufacture. Castellated regions are formed on the edge of the component package using the appropriate sized drill or milling bit. Edge plating is applied to the castellated surfaces to create edge pads. The edge plating provides electrical continuity between the edge pads and the SMT pads. Solder mask, or other materials, is applied to prevent solder from wicking between each SMT pad and its respective edge pad. Such component may be attached to a larger device PWB using either the edge pads or the SMT pads, or may even be attached using a combination of the two, such as in the event of a pad failure or other defect.