Substrate Stiffener Structure for Ultra-Thin Package Warpage
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Solution Overview
Problem
Integrated circuit (IC) packages face warpage issues due to mismatched thermal expansion coefficients between thin dies and substrates, leading to bending, twisting, and lack of flatness, which affects solder joint formation and package assembly, particularly in ultra-thin designs.
Innovation Solution
Incorporating a stiffener, such as a ring or frame, attached to the substrate perimeter or within the core, made from materials like metals or ceramics, to counteract warpage by providing mechanical support and maintaining planarity, using techniques like thermal compression bonding or adhesive attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a thin die is used to reduce package thickness, then the package becomes ultra-thin, but warpage increases due to mismatched thermal expansion coefficients
Solution Approach 1:
The patent applies local quality by placing stiffeners at specific locations on the substrate - typically at the corners and/or center - rather than uniformly across the entire substrate. This localized reinforcement provides sufficient mechanical support to counteract warpage in ultra-thin packages while minimizing the addition of material and maintaining the overall thin profile of the package.
Solution Approach 2:
The patent employs composite materials by combining the substrate material with stiffener materials that have different mechanical properties. The stiffeners are made from materials with higher modulus of elasticity than the substrate, creating a composite structure that enhances rigidity and resistance to thermal expansion mismatch without significantly increasing package thickness.
2Stability of the object's composition
If stiffener material is added to counteract warpage, then package flatness is maintained, but manufacturing complexity increases
Solution Approach 1:
The patent segments the stiffening function into discrete stiffener elements that can be independently manufactured and positioned on the substrate. These segmented stiffeners simplify the manufacturing process compared to creating a fully integrated complex reinforcement structure, allowing for easier assembly and quality control while maintaining package flatness.
Solution Approach 2:
The patent introduces an intermediary adhesive layer between the substrate and the stiffener. This adhesive mediator simplifies the manufacturing process by enabling straightforward bonding of the stiffener to the substrate through standard adhesive application techniques, rather than requiring more complex mechanical or metallurgical joining methods.
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
The stiffener effectively reduces warpage, ensuring better solder joint formation and assembly stability, enhancing the reliability and yield of IC packages by maintaining flatness and preventing yield losses during reflow processes.
Implementation Method 1
Incorporating a stiffener, such as a ring or frame, attached to the substrate perimeter or within the core, made from materials like metals or ceramics, to counteract warpage by providing mechanical support and maintaining planarity
Implementation Method 2
using techniques like thermal compression bonding or adhesive attachment
Data Source
AI summary
Disclosed herein are microelectronic assemblies, as well as related apparatuses and methods. In some embodiments, a microelectronic assembly may include a substrate having a first surface and an opposing second surface; a die electrically coupled to the second surface of the substrate; and a stiffener attached to the first surface of the substrate configured to mitigate warpage of the die.