Closed Loop Leads for Semiconductor Package Thermal Strain
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Solution Overview
Problem
Existing semiconductor packages face challenges in managing thermal strain during the wire bonding process, as leads act as cantilevered beams, leading to potential damage from thermal stresses and displacement of free ends.
Innovation Solution
The semiconductor package design features closed loop leads that connect both ends to the dam-bar, reducing thermal strain by rerouting stress back to the dam-bar and eliminating free ends susceptible to deformation, while also configuring leads to partially surround other leads for enhanced support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If leads are configured as cantilevered beams in existing semiconductor packages, then the leads can be simply structured and manufactured, but the leads are susceptible to thermal strain and displacement during the wire bonding process
Solution Approach 1:
The patent inverts the conventional cantilevered beam lead structure by configuring leads as closed loops where both ends connect to the dam-bar. This inversion eliminates the free end that is susceptible to thermal strain, transforming the lead from a cantilevered beam into a closed loop structure that reroutes stress back to the dam-bar, thereby resolving the contradiction between manufacturing simplicity and thermal strain resistance
Solution Approach 2:
The patent changes the structural parameter of the lead from a cantilevered beam with one fixed end and one free end to a closed loop with both ends fixed to the dam-bar. This parameter change in the lead configuration fundamentally alters the stress distribution characteristics, enabling the lead to withstand thermal strain during wire bonding while maintaining structural integrity
2Reliability
If leads are configured as closed loops connecting both ends to the dam-bar, then thermal strain is minimized and reliability is improved, but the device complexity increases
Solution Approach 1:
The closed loop lead structure serves multiple functions simultaneously: it provides mechanical support, reroutes thermal stress back to the dam-bar, and eliminates the need for additional strain relief features. This multi-functionality reduces overall device complexity despite the changed lead configuration, as the same structural element accomplishes multiple objectives that would otherwise require separate components
3Stability of the object's composition
If leads are partially surrounded by other leads, then mechanical support and stability are enhanced, but the manufacturing process becomes more complex
Solution Approach 1:
The patent merges multiple lead functions into a single integrated lead structure where one lead partially surrounds another, creating a nested configuration. This combining of leads provides enhanced mechanical stability and mutual support while being manufactured as an integrated component, thereby reducing assembly complexity despite the intricate geometric arrangement
4Object-affected harmful factors
If the second end of the first lead is encapsulated entirely within the insulating layer, then protection from moisture and physical contact is improved, but the lead configuration becomes more complex
Solution Approach 1:
The patent employs a nested configuration where the insulating layer encapsulates the second end of the first lead, creating a protective envelope. This nesting arrangement provides comprehensive protection from moisture and physical contact while integrating seamlessly with the overall package structure, avoiding the need for separate protective components and thereby managing complexity efficiently
Data Source
AI summary
A semiconductor package includes a first lead with first and second ends extending in the same direction as one another. At least one second lead has first and second ends and is partially surrounded by the first lead. A die pad is provided and a die is connected to the die pad. Wires electrically connect the die to the first lead and the at least one second lead. An insulating layer extends over the leads, the die pad, and the die such that the first end of the at least one second lead is exposed from the semiconductor package and the second end of the first lead is encapsulated entirely within the insulating layer.