Elevated Die Paddle for Stacked Semiconductor Packages
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Stacked-die semiconductor packages face issues such as premature die failure, difficulty in designing due to overlying components, varying bonding wire lengths, heat dissipation challenges, adhesive moisture absorption, and thermal mismatch, leading to reduced reliability and increased manufacturing complexity.
Innovation Solution
The use of an elevated die paddle structure within a leadframe, supported by a die attach adhesive, and electrical connection via a ball grid array, along with underfill material and encapsulant for structural support, addresses these challenges by providing stability and reducing adhesive usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple dies are stacked in a semiconductor package, then circuit density is increased, but heat dissipation becomes more difficult
Solution Approach 1:
The patent transitions from lateral heat dissipation to vertical heat dissipation by stacking dies in the Z-dimension. The elevated die paddle structure provides vertical thermal pathways through the package, allowing heat to dissipate in multiple dimensions rather than being constrained to lateral pathways only.
Solution Approach 2:
The elevated die paddle acts as an intermediary thermal management structure between the stacked dies and the package substrate. It provides dedicated thermal vias and heat sinking capabilities that mediate heat transfer from multiple dies without requiring direct contact between all dies and the substrate.
2Adaptability or versatility
If an upper die overhangs the next lower die in the stack, then design flexibility is improved, but the upper die may crack during wire-bonding due to lack of vertical support
Solution Approach 1:
The elevated die paddle serves as an intermediary support structure that provides vertical mechanical support to overhanging dies during wire-bonding operations. This mediator structure allows design flexibility while preventing die cracking by distributing mechanical loads.
Solution Approach 2:
The elevated die paddle provides pre-established mechanical support and stress distribution before wire-bonding operations begin. This beforehand cushioning prevents cracking by ensuring structural integrity is in place prior to applying bonding forces.
3Stability of the object's composition
If more adhesive material is used to position stacked dies, then die positioning stability is improved, but moisture absorption increases which reduces reliability
Solution Approach 1:
The elevated die paddle structure extracts the mechanical positioning function from adhesive materials. By providing structural support through the paddle geometry and leadframe construction, the patent reduces reliance on adhesive for positioning stability, thereby minimizing moisture absorption risks.
Solution Approach 2:
The invention changes the parameter of adhesive quantity from high to low by introducing the elevated die paddle structure. This parameter change maintains positioning stability through structural design rather than material volume, reducing moisture-related reliability issues.
4Adaptability or versatility
If bonding wires of various lengths are used to accommodate different die layouts, then layout flexibility is improved, but parasitic inductance and capacitance increase
Solution Approach 1:
The elevated die paddle provides a universal reference plane and standardized wire bonding height for all dies in the stack. This multi-functional structure allows consistent wire lengths to be used across different die layouts, maintaining layout flexibility while controlling parasitics through geometric standardization.
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 configuration reduces die cracking during wire bonding, enhances heat dissipation, minimizes adhesive-related issues, and increases package reliability, allowing for more efficient and cost-effective manufacturing of smaller, higher-density semiconductor packages.
Implementation Method 1
a first die attached to a lower surface of the elevated die paddle to support the first die within the semiconductor package
Implementation Method 2
electrical connection via a ball grid array
Implementation Method 3
the head of a wire-bonding apparatus applies a downward pressure on a conductive wire held in contact with a wire-bonding pad on the die to weld, or bond, the wire to the bonding pad on the die
Implementation Method 4
automated wire-bonding equipment employing well-known thermal compression or ultrasonic wire-bonding techniques
Implementation Method 5
enclose the stack of dies in one package
Data Source
AI summary
A semiconductor package includes a leadframe, an elevated die paddle disposed above the leadframe, a first die attached to a lower surface of the elevated die paddle to support the first die within the semiconductor package, and a second die attached to the first die. A method of manufacturing a semiconductor package includes providing a leadframe having a lower lead and an elevated die paddle structure, attaching a first die to the elevated die paddle structure with a die adhesive (DA) for supporting the first die within the semiconductor package, and wire bonding the first die to the lower lead.