Dual Lead Frame Semiconductor Assembly for High Density
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Solution Overview
Problem
The existing assembly process for semiconductor devices using a single lead frame limits the number of devices that can be manufactured and increases the complexity of the process, as it requires the same lead frame to both mount the die and form the leads, thereby restricting the number of dies that can be assembled and extending the process length.
Innovation Solution
The use of two lead frames, one for mounting the die and another for providing the leads, allows for improved assembly efficiency by separating the die mounting and lead formation processes, enabling more devices to be assembled simultaneously while reducing the number of steps involved.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single lead frame is used for both die mounting and lead formation, then the assembly process is simplified, but the number of devices that can be manufactured is limited and process complexity increases
Solution Approach 1:
The invention divides the traditional single lead frame system into two separate lead frames: a first lead frame dedicated to die mounting and a second lead frame dedicated to lead formation. This segmentation allows each lead frame to be optimized for its specific function, enabling higher density die mounting on the first lead frame while the second lead frame provides the necessary lead structures, thereby increasing overall manufacturing productivity without compromising process simplicity
Solution Approach 2:
The invention introduces a vertical stacking dimension by attaching the second lead frame to the first lead frame in an overlapping configuration. This dimensional change allows the lead formation function to be added without increasing the horizontal footprint, enabling more dies to be mounted per unit area on the first lead frame while maintaining the necessary lead structures through the vertical arrangement
2Device complexity
If a single lead frame is used for both die mounting and lead formation, then fewer components are required, but the number of dies that can be mounted per unit area is restricted
Solution Approach 1:
By separating die mounting and lead formation functions into two distinct lead frames, the invention allows the first lead frame to be densely packed with dies without the space constraints imposed by integrated lead structures. The second lead frame is attached in an overlapping configuration, allowing leads to extend from the assembly without occupying horizontal mounting space on the first lead frame, thereby increasing dies per unit area
Solution Approach 2:
The vertical stacking of the second lead frame over the first lead frame utilizes the Z-dimension to provide lead structures without consuming horizontal mounting area. This dimensional transition allows maximum utilization of the first lead frame surface for die mounting while the second lead frame provides necessary electrical connections through the vertical arrangement
3Duration of action of moving object
If a single lead frame is used for both die mounting and lead formation, then the assembly process is shorter, but lead formation time increases
Solution Approach 1:
The invention segments the assembly process into two independent stages: die mounting on the first lead frame and lead formation using the second lead frame. This segmentation allows parallel processing where die mounting and lead formation can be performed simultaneously on different lead frames, reducing the overall assembly process length while maintaining efficient lead formation through the dedicated second lead frame structure
Data Source
AI summary
A packaged semiconductor device is assembled using a first lead frame upon which a die is mounted and encapsulated and a second lead frame that provides bent leads for the device. By using two different lead frames, an array of the first lead frames can be configured with more lead frames for more devices than a comparably sized lead frame array of the prior art because the first lead frame array does not need to provide the leads for the packaged devices. Instead, the leads are provided by the second lead frame array, which can be attached to the first lead frame array after the dies have been mounted and encapsulated on the first lead frame array.