Lead Frame Accommodating Various Die Sizes
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Solution Overview
Problem
There is a need for a cost-effective integrated circuit (IC) packaging solution that can accommodate various size dies while meeting electrical and mechanical requirements, including increased I/Os and efficient thermal management.
Innovation Solution
A semiconductor device design featuring a lead frame with proximal and distal ends, a heat sink attached to the bottom surface, and a semiconductor die attached to the top surface, where bond wires connect the die electrodes to the leads, and an encapsulant covers the assembly, allowing for external electrical communication and thermal dissipation through the leads and heat sink.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional lead frame design is used, then the structure is simple and easy to manufacture, but it cannot accommodate various size dies and has limited I/O capacity
Solution Approach 1:
The lead frame is designed with a universal structure that can accommodate various die sizes through a recessed die receiving area with flexible lead arrangements. The leads can be configured in different patterns and the die receiving area can adjust to different die dimensions, allowing one lead frame design to serve multiple die size requirements.
2Reliability
If more I/Os are added to meet electrical requirements, then the electrical performance improves, but the package size increases and cost increases
Solution Approach 1:
The die is positioned within a recessed die receiving area formed by the lead frame structure itself. The leads are arranged to surround and support the die within this nested configuration, allowing multiple I/O connections in a compact arrangement that maximizes electrical performance without proportionally increasing package size.
3Reliability
If bond wire length is reduced to enhance electrical performance, then on-resistance decreases, but the packaging design becomes more constrained
Solution Approach 1:
The lead frame structure provides localized support and positioning features specifically at the die receiving area. The proximal ends of the leads are positioned close to the die to minimize bond wire length, while the distal ends extend outward for external connections. This localized optimization of lead positioning achieves low on-resistance without requiring complex overall package redesign.
4Temperature
If thermal management is improved through heat dissipation, then device reliability increases, but the package structure becomes more complex
Solution Approach 1:
The lead frame serves multiple functions simultaneously: it provides electrical connections through the leads, mechanical support for the die through the recessed receiving area, and thermal management through the conductive lead structure that conducts heat away from the die. By merging these functions into a single integrated component, thermal performance is improved without adding separate thermal management structures that would increase complexity.
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 enables cost-effective packaging that supports various die sizes, increases lead count, enhances electrical performance by reducing bond wire length, and improves thermal management by allowing heat dissipation, resulting in a QFN type package with good on-resistance and thermal performance.
Implementation Method 1
a heat sink attached to a bottom surface of the plurality of leads
Data Source
AI summary
A semiconductor device is assembled using a lead frame having leads that surround a central opening. The leads have proximal ends near to the central opening and distal ends spaced from the central opening. A heat sink is attached to a bottom surface of the leads and a semiconductor die is attached to a top surface of the leads, where the die is supported on the proximal ends of the leads and spans the central opening. Bond wires electrically connect electrodes on an active surface of the die and the leads. An encapsulant covers the bond wires and at least the top surface of the leads and the die. The distal ends of the leads are exposed to allow external electrical communication with the die.