Molded Power Semiconductor Package Openings for Flash-Free Pin Contacts
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Solution Overview
Problem
Molded power semiconductor packages face interference from a thin layer of mold flash during electrical testing and attachment of pins to the metallic structure, which hinders the testing process and subsequent pin placement.
Innovation Solution
The solution involves creating openings in the mold compound that expose contact areas of a metallic frame, allowing for reliable removal of mold compound flash using a chemical de-flashing agent and enabling secure pin attachment. These openings are dimensioned to increase contact area with the de-flashing agent and may extend to the edge of the mold compound to form an open channel for efficient agent flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the mold compound is used to embed power semiconductor dies and metallic structure, then encapsulation and protection are improved, but mold flash interferes with electrical testing and pin attachment
Solution Approach 1:
The mold compound is segmented by creating openings that divide the encapsulation into regions with and without flash, allowing the flash to be isolated and removed from contact areas while maintaining encapsulation protection in other regions
Solution Approach 2:
The harmful mold flash is extracted from the contact areas through the openings, allowing it to be separated and removed from the metallic structure surfaces that require electrical testing and pin attachment
2Ease of operation
If openings are created in the mold compound to expose contact areas, then electrical testing and pin attachment are enabled, but the mold compound structure is modified
Solution Approach 1:
The mold compound structure is modified locally only at the contact areas where openings are created, while the rest of the encapsulation maintains its original protective structure, minimizing overall structural complexity
3Ease of manufacture
If conventional molding is used without openings, then manufacturing simplicity is maintained, but de-flashing process cannot access contact areas
Solution Approach 1:
The openings are created in the mold compound during the molding process itself, before the de-flashing operation, thereby preliminarily preparing access paths that enable efficient flash removal in subsequent steps
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures reliable electrical testing and secure pin placement by effectively removing mold flash and improving contact reliability, facilitating the formation of permanent external contacts.
Implementation Method 1
performing a de-flashing process to remove mold compound flash from the contact areas of the metallic frame, wherein each open channel provides an ingress or egress path for a chemical de-flashing agent of the de-flashing process
Data Source
AI summary
A molded power semiconductor package includes a mold compound having first and second opposing main surfaces and an edge between the first and second main surfaces. Power semiconductor dies are embedded in the mold compound. A metallic frame embedded in the mold compound is electrically connected to the power semiconductor dies. Pins protrude from the first main surface of the mold compound, each pin being secured to a respective contact area of the metallic frame that is exposed by an opening in the mold compound at the first main surface. One or more of the openings extends to the edge of the mold compound to form an open channel from each contact area exposed by the one or more of the openings to the edge of the mold compound. Additional package embodiments and methods of production are also described.