L-Shaped Lead Semiconductor Package for Coplanar Contact
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Solution Overview
Problem
Conventional semiconductor packaging methods require terminals on opposite sides of the die, making it challenging to achieve compact, economical, and efficient packaging with all terminals on the same side for devices like vertical power MOSFETs.
Innovation Solution
A semiconductor package design featuring L-shaped upper leads electrically coupled to a die on one side and lower leads, with a method involving etched lead frames, solder coupling, and encapsulation to ensure all package contacts are coplanar, allowing for surface mounting and thermal cycle resilience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional packaging with die between upper and lower lead frames is used, then electrical coupling is achieved, but package size increases and all terminals cannot be on the same side
Solution Approach 1:
The upper leads are bent into an L-shape configuration, transitioning from a conventional planar arrangement to a three-dimensional structure. This dimensional change allows the leads to extend vertically from the upper lead frame, bend at a right angle, and then extend horizontally to contact the die terminals on the front side, enabling all package contacts to be coplanar on a single side while maintaining electrical connectivity.
Solution Approach 2:
The upper leads are divided into distinct functional segments: a vertical portion extending from the upper lead frame, a bent portion at approximately 90 degrees, and a horizontal portion contacting the die terminals. This segmentation allows each portion to fulfill its specific function while contributing to the overall goal of having all external contacts on one side of the package.
2Volume of moving object
If compact packaging is achieved, then package size reduces, but manufacturing complexity increases
Solution Approach 1:
The upper leads are pre-bent into the L-shape configuration before the die attachment process. This preliminary action simplifies the subsequent manufacturing steps, as the leads are already positioned to receive the die and make proper contact without requiring complex real-time adjustment or additional bending operations during assembly.
3Ease of operation
If all terminals are on the same side, then ease of mounting improves, but achieving coplanar contacts becomes difficult
Solution Approach 1:
The L-shaped configuration of the upper leads pre-compensates for potential misalignment issues. By positioning the horizontal portion of the leads at a controlled distance from the upper lead frame and orienting them parallel to the front surface of the die, the design proactively ensures coplanarity of all external contacts, preventing mounting issues before they occur.
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
The solution enables compact, thermally and electrically conductive semiconductor packages with all contacts in a single plane, reducing package size and preventing solder or die cracking during thermal cycles without additional lower leads.
Implementation Method 1
The terminals of the die 130 are electrically coupled to the lead 110, 115, 135 by means of solder layers.
Data Source
AI summary
The present technology is directed toward semiconductors packaged by electrically coupling a plurality of die to an upper and lower lead frame. The opposite edges of each corresponding set of leads in the upper lead frame are bent. The leads in the upper lead frame are electrically coupled between respective contacts on respective die and respective lower portion of the leads in the lower lead frame. The bent opposite edges of each corresponding set of leads of the upper lead frame support the upper lead frame before encapsulation, for achieving a desired position of the plurality of die between the leads of the upper and lower lead frames in the packaged semiconductor. After the encapsulated die are separated, the upper leads have an L-shape and electrically couple die contacts on upper side of the die to leads on the lower side of the die so that the package contacts are on the same side of the semiconductor package.