Downset Lead Frame for High-Density Semiconductor Chip Integration
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Solution Overview
Problem
The existing methods for fabricating semiconductor devices on lead frames are inefficient, particularly in coupling multiple semiconductor chips to die pads in a batch process, as they often require complex processes and are not well-suited for planar lead frames with a downset configuration.
Innovation Solution
A semiconductor device design featuring a planar first lead frame with a die pad and a second lead frame coupled to it, where the die pad is downset with respect to the leads, allowing for simplified chip attachment and integration using methods like diffusion soldering or sintering, and subsequent coupling of the second lead frame to the first using welding or soldering, enabling batch processing and high-density chip attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple semiconductor chips are coupled to die pads in a batch process on planar lead frames, then manufacturing efficiency is enhanced, but the fabrication process becomes more complex
Solution Approach 1:
The lead frame is divided into multiple die pads arranged in a grid pattern, allowing simultaneous attachment of multiple semiconductor chips in a batch process. This segmentation enables parallel fabrication operations, improving productivity while maintaining manageable process complexity through standardized repetitive structures.
Solution Approach 2:
The lead frame is pre-configured with multiple die pads in predetermined positions before chip attachment. This preliminary arrangement of attachment locations enables efficient batch processing by eliminating the need for sequential positioning operations, thereby enhancing manufacturing efficiency without proportionally increasing process complexity.
2Ease of manufacture
If the die pad is downset with respect to the leads, then chip attachment is simplified, but the lead frame structure becomes more complex
Solution Approach 1:
The lead frame exhibits local quality variation through the downset feature, where the die pad region is positioned at a lower elevation than the leads. This localized structural modification simplifies chip attachment by providing a recessed mounting surface, while the overall lead frame structure remains relatively simple through this targeted geometric change.
Solution Approach 2:
The downset feature introduces a vertical dimension difference between the die pad and leads, creating a stepped configuration. This dimensional change simplifies chip attachment by providing natural positioning and mechanical retention, while adding only minimal structural complexity to the lead frame design.
3Quantity of substance
If high-density chip integration is achieved, then device functionality is enhanced, but manufacturing difficulty increases
Solution Approach 1:
The lead frame is segmented into multiple die pads arranged in a dense grid pattern, enabling high-density chip integration. This systematic segmentation allows for standardized batch processing techniques to be applied, maintaining manufacturing ease despite increased chip density by using repetitive, scalable fabrication operations.
Solution Approach 2:
Multiple die pads are pre-positioned in predetermined locations on the lead frame before chip attachment. This preliminary configuration enables high-density integration by providing all necessary mounting locations in advance, allowing chips to be attached in a single batch operation rather than through complex sequential positioning, thereby maintaining manufacturing ease.
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 design simplifies the attachment process for multiple semiconductor chips on planar lead frames, enhances manufacturing efficiency, and allows for high-density chip integration while maintaining electrical and thermal coupling, facilitating easier encapsulation and singulation of semiconductor devices.
Implementation Method 1
coupling one semiconductor chip at a time to a die pad of the lead frame strip
Implementation Method 2
diffusion soldering or sintering
Implementation Method 3
coupling of the second lead frame to the first using welding or soldering
Implementation Method 4
coupling of the second lead frame to the first using welding or soldering
Data Source
AI summary
A semiconductor device includes a planar first lead frame including a die pad, a semiconductor chip coupled to the die pad, and a second lead frame coupled to the first lead frame. The second lead frame includes leads arranged such that the die pad is downset with respect to the leads.