High-Draft Package Structure for Void-Free Mold Filling
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Solution Overview
Problem
Imbalanced flow of molding material during the molding process of packaged electronic devices, particularly for high voltage mold compound, leads to incomplete filling and the formation of mold voids or gaps, which can be costly and complex to address through mold parameter optimization.
Innovation Solution
A molded package structure with lateral sides extending at an angle greater than 15 degrees and 25 degrees or less to facilitate balanced mold cavity filling and mitigate mold voids, achieved by using a mold with corresponding draft angles during the molding process, allowing for partial exposure of conductive leads and enhanced material flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional molding process is used with vertical or low draft angle sidewalls, then package height can be achieved, but imbalanced flow of molding material occurs leading to incomplete filling and mold voids
Solution Approach 1:
The patent changes the geometric parameter of the mold cavity sidewalls by introducing a draft angle greater than 15 degrees. This parameter modification enables balanced flow of high voltage mold compound during injection, preventing imbalanced flow patterns that cause voids and incomplete filling, thereby resolving the contradiction between achieving tall package height and preventing mold defects
Solution Approach 2:
The patent introduces asymmetric tapering to the mold cavity sidewalls through the draft angle design. Instead of vertical or low-angle sidewalls that create flow imbalance, the asymmetric tapered geometry guides the molding material flow uniformly, eliminating the harmful void formation while maintaining the required package dimensions
2Manufacturing precision
If mold parameter optimization is used to address mold voids, then void formation can be reduced, but manufacturing cost and complexity increase
Solution Approach 1:
The patent applies preliminary action by incorporating the draft angle into the mold cavity design before the molding process begins. This pre-designed geometric feature proactively prevents flow imbalance and void formation, eliminating the need for complex post-process optimizations or adjustments to molding parameters, thereby reducing both cost and complexity
Data Source
AI summary
An electronic device includes a molded package structure and a conductive lead partially exposed outside the package structure, the package structure having lateral sides extending at an angle that is greater than 15 degrees and 25 degrees or less to facilitate mold cavity filling during package molding and mitigate mold voids in the electronic device. A method of fabricating an electronic device includes attaching a die to a lead frame, electrically coupling a conductive terminal of the die to a conductive lead and performing a molding process using a mold having cavity sidewalls with a draft angle greater than 15 degrees and 25 degrees or less to form a package structure that encloses the die and partially encloses the conductive lead.