Lead Frame Etched Isolation for Die Burr Short Prevention
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Solution Overview
Problem
Existing methods for preventing metal burrs from contacting lead frames in semiconductor packaging are unreliable and require additional processes or materials, leading to potential electrical leakage and shorting.
Innovation Solution
The implementation of a lead frame design with etched areas filled with a non-conductive mold compound, where the metal burr from the silicon die comes into contact with the mold compound rather than the lead frame, providing electrical isolation and eliminating the need for additional materials or processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional material is added to increase the gap between the lead frame and metal material, then electrical isolation is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent removes material from the lead frame to create an etched area, eliminating the need for additional isolating material. This extraction approach achieves electrical isolation by removing the conductive path rather than adding a barrier, thereby reducing device complexity while maintaining reliability
Solution Approach 2:
The etched area acts as an intermediary zone between the lead frame and metal material coating. This intermediate region provides electrical isolation through its non-conductive nature (after mold compound filling) without requiring separate isolating components, thus improving reliability without increasing structural complexity
2Reliability
If additional processes are implemented to prevent metal burr contact, then electrical isolation is improved, but manufacturing complexity and time increase
Solution Approach 1:
The etched area is created during the lead frame manufacturing process before die attachment. This preliminary action ensures that when metal burrs occur during subsequent dicing, they are already positioned to contact the etched area rather than the lead frame, achieving electrical isolation without requiring additional post-processing steps
Solution Approach 2:
The patent converts the harmful effect of metal burrs (which can cause electrical shorting) into a beneficial outcome by designing the etched area to intentionally receive the burrs. The burrs that would otherwise be defects are redirected to contact the non-conductive etched area, thereby preventing electrical leakage while using the same manufacturing processes
3Reliability
If the mounting pad area is reduced to prevent burr contact, then electrical isolation is improved, but the area for thermal conduction and electrical connection is reduced
Solution Approach 1:
The lead frame is segmented into distinct functional zones: the mounting pad area for thermal and electrical connection, and the etched area for electrical isolation. This segmentation allows the mounting pad to maintain its full area for optimal thermal conduction while the separate etched area provides the necessary electrical isolation, resolving the contradiction between connection area and isolation effectiveness
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 solution effectively prevents electrical leakage and shorting while reducing production costs and complexity, maintaining thermal conductivity and improving production yield by eliminating the need for additional materials or processes.
Implementation Method 1
an etched area filled with a non-conductive mold compound on a side of the lead frame that comes into contact with an end of the silicon die
Implementation Method 2
A volume of epoxy material is dispensed onto the lead frame along a length of the metal material coating to form a fillet weld on a side of the silicon die configured to adhere the silicon die to the lead frame
Data Source
AI summary
A semiconductor device includes a silicon die having a metal material coating applied on one side, a lead frame having a mounting pad having an area smaller than an area of the silicon die, the silicon die being mounted on the lead frame via the mounting pad, and an etched area filled with a non-conductive mold compound on a side of the lead frame that comes into contact with an end of the silicon die along an edge of the silicon die. A volume of epoxy material is dispensed onto the lead frame along a length of the metal material coating to form a fillet weld on a side of the silicon die configured to adhere the silicon die to the lead frame and to prevent the metal material coating from coming into contact with the lead frame.