Thick Die Pad IC Package Heat Sink Design
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Solution Overview
Problem
Existing IC packages with thicker die pads face challenges in precision production of fine pitch inner leads and are prone to delamination due to thermal expansion mismatch, leading to increased thermal resistance and potential early thermal shutdown.
Innovation Solution
An IC package design where the die pad is formed separately from the lead frame, allowing for a thicker die pad that is at least twice the thickness of the leads, with the leads' upper and lower surfaces being coplanar with the die pad's surfaces, and using a dual-layer encapsulating material with higher quality on top and lower quality on the bottom to reduce wire sweep and production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the die pad thickness is increased to improve heat dissipation, then heat dissipation capability is improved, but manufacturing precision of lead end portions deteriorates
Solution Approach 1:
The lead frame structure is segmented into multiple thickness zones: a thick die pad portion for heat dissipation, intermediate thickness peripheral portions, and thin lead portions for precise end formation. This segmentation allows each part to have optimized thickness for its specific function, resolving the contradiction between heat dissipation and manufacturing precision.
2Temperature
If the die pad thickness is increased to improve heat dissipation, then heat dissipation capability is improved, but production difficulty increases
Solution Approach 1:
Different regions of the lead frame are assigned different thickness qualities: the die pad region has large thickness for heat dissipation, while the lead regions have small thickness for ease of formation. This local quality differentiation allows the thick die pad to be produced without compromising overall manufacturability.
3Temperature
If different thickness sections are used in the lead frame, then heat dissipation is improved, but device complexity increases
Solution Approach 1:
The lead frame is designed as a single integrated component that incorporates multiple thickness zones, merging the die pad and lead functions into one piece. This eliminates the need for separate die pad and lead frame components, reducing assembly complexity while maintaining the benefits of differential thickness.
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 reduces the risk of delamination, allows for easier formation of leads with precise end portions, and enhances heat dissipation while minimizing production costs and thermal resistance.
Implementation Method 1
the die pad serves as a heat sink wherein a lower surface of the die pad may be exposed to dissipate heat from the IC die
Implementation Method 2
An encapsulating material body surrounds the die pad and IC die
Data Source
AI summary
An integrated circuit (IC) package includes a die pad and an IC die secured on the die pad. The IC die had outer edges aligned with outer edges of the die pad. An encapsulating material body surrounds the die pad and IC die. Leads extend outwardly from the encapsulating material body and are coupled to the IC die. Each lead has an upper surface coplanar with an upper surface of the IC die. The die pad has a lower surface exposed through the encapsulating material body, and has a thickness greater than a thickness of each of the plurality of leads.