Molded Power Module Pin Layout for Alignment and Low Inductance
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Solution Overview
Problem
Existing semiconductor device modules face challenges with alignment of substrates in molding cavities, leading to improper placement of signal pins and power tabs, stray inductance due to power tab configuration, and non-interchangeability of modules with different signal pin arrangements, as well as delamination of molding compound from thermal dissipation appliances during thermal cycling.
Innovation Solution
The solution involves an electronic device assembly with a substrate, patterned metal layer, and molded body featuring signal pins and power tabs with specific configurations, including alignment features and internal/external portions for secure positioning, and an interposer with signal pin sockets and conductive posts for consistent signal pin arrangements and reduced stray inductance, along with a thermal dissipation appliance design that anchors the molding compound to prevent delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional molding encapsulation is used, then the module can be manufactured, but alignment of substrate in molding cavity becomes difficult resulting in improper location of signal pins and power tabs
Solution Approach 1:
Alignment features (protrusions and recesses) are pre-formed on the substrate and molded body before final encapsulation. These features guide the substrate's position in the molding cavity, ensuring proper alignment of signal pins and power tabs with the molded body openings before the molding compound is applied.
Solution Approach 2:
The alignment features act as intermediary elements between the substrate and the molding cavity. The protrusions on the substrate engage with corresponding recesses in the molded body, serving as mechanical guides that mediate the positioning relationship and ensure precise alignment during encapsulation.
2Ease of operation
If power tabs are made longer to extend from molding compound, then external electrical connection is achieved, but stray inductance increases significantly
Solution Approach 1:
Power tabs are configured to extend in multiple dimensions: horizontally within the substrate plane for minimal inductance, and vertically through the molding compound via formed openings. This multi-dimensional arrangement allows external electrical connection while minimizing the inductive loop area by keeping the current path as compact as possible.
Solution Approach 2:
The power tab structure is segmented into multiple portions: a first portion extending horizontally from the substrate, and a second portion extending vertically through the molding compound. This segmentation allows optimization of each portion's function - the horizontal portion minimizes inductance while the vertical portion provides external accessibility.
3Reliability
If signal pins are attached during molding process, then encapsulation is achieved, but signal pins become misaligned due to slanting during attachment
Solution Approach 1:
Signal pin openings are pre-formed in the molded body at precise locations corresponding to the substrate's signal pin positions. Alignment features are also pre-formed to ensure the substrate is positioned correctly relative to these openings before encapsulation, preventing slanting during the molding process.
Solution Approach 2:
The traditional mechanical attachment method that causes slanting is replaced with a precision molding process. The molded body is formed with precise openings and alignment features that mechanically guide the substrate into correct position, eliminating the slanting problem associated with post-attachment methods.
4Reliability
If molding compound is applied over thermal dissipation appliance, then encapsulation is achieved, but delamination occurs during thermal cycling
Solution Approach 1:
Grooves are pre-formed in the thermal dissipation appliance surface before applying the molding compound. These grooves create mechanical interlocking features that prevent delamination during thermal cycling, while still allowing the molding compound to encapsulate the assembly for protection.
Solution Approach 2:
The thermal dissipation appliance incorporates grooves that create a composite structure with the molding compound. The grooves allow the molding compound to flow into and interlock with the thermal dissipation appliance, creating a mechanically bonded composite structure that resists delamination under thermal stress.
Data Source
AI summary
In a general aspect, an electronic device assembly includes a substrate having a surface, a patterned metal layer disposed on the surface of the substrate, a semiconductor device circuit implemented on the patterned metal layer, and a molded body including a plurality of signal pin. A signal pin of the plurality of signal pins includes a first portion extending out of a first surface of the molded body. The first portion is externally accessible. The signal pin of the plurality of signal pins also includes a second portion extending out of a second surface of the molded body opposite the first surface. The second portion of the signal pin of the plurality of signal pins include is internal to the electronic device assembly, is electrically coupled with the patterned metal layer, and is electrically continuous with the first portion.