Self-Aligned Stacked-Die Microelectronics Package
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Solution Overview
Problem
Traditional stacked-die assemblies in microelectronics packages face challenges with poor alignment, leading to variability in magnetic coupling coefficients and reduced signal transfer performance, which requires expensive and complex alignment techniques, and result in a bulky package that does not meet low-profile requirements for modern portable devices.
Innovation Solution
A self-aligned stacked-die assembly is achieved by using a thinned flip chip die with a mold compound that provides vertical walls aligned with the die edges, allowing a second die to be stacked with precise alignment, eliminating the need for electrical connections and enabling stable magnetic coupling without significant variability, thus reducing the package thickness and improving signal transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional stacked-die assembly is used, then the package can accommodate multiple semiconductor dies, but the alignment between stacked dies is poor leading to variability in magnetic coupling coefficients
Solution Approach 1:
The mold compound structure provides self-alignment through its vertical walls that are aligned with the edges of the thinned flip chip die. When the second die is stacked within the opening defined by these vertical walls, the geometry of the mold compound automatically guides and constrains the horizontal position of the second die, achieving precise alignment without requiring expensive external alignment equipment or complex alignment processes.
2Manufacturing precision
If expensive optical alignment techniques are used to improve alignment precision, then manufacturing cost increases significantly
Solution Approach 1:
The mold compound structure provides self-alignment through its vertical walls that are aligned with the edges of the thinned flip chip die. When the second die is stacked within the opening defined by these vertical walls, the geometry of the mold compound automatically guides and constrains the horizontal position of the second die, achieving precise alignment without requiring expensive external alignment equipment or complex alignment processes.
3Length of stationary object
If thicker semiconductor dies are used, then the package thickness increases, but this may not meet low-profile requirements
Solution Approach 1:
The patent applies thinning processes to reduce the thickness of the flip chip die from its original thicker state to a thinned state with controlled thickness. This parameter change enables the die to meet low-profile package requirements while maintaining structural integrity through controlled thinning processes and appropriate thickness specifications.
Solution Approach 2:
The package structure is segmented into distinct functional layers including the thinned flip chip die, the mold compound with vertical walls, and the opening structure. This segmentation allows each component to be optimized independently - the die can be thinned to meet profile requirements while the mold compound provides structural support and alignment functions.
4Loss of energy
If the distance between inductive coupling components is increased, then more energy is lost through escaped magnetic flux, but this may be necessary due to die thickness variations
Solution Approach 1:
The self-aligned stacking structure creates a controlled spatial relationship between the thinned flip chip die and the second die, maintaining a consistent and minimized vertical distance between their respective inductive coupling components. This precise spatial control ensures optimal magnetic coupling efficiency by minimizing the air gap through which magnetic flux could escape, thereby reducing energy loss.
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 self-aligned stacked-die assembly enhances signal transferring performance, reduces the package thickness, and eliminates the need for expensive alignment techniques, resulting in a more efficient and cost-effective microelectronics package that meets low-profile requirements.
Implementation Method 1
magnetic coupling, which does not require electric connections, may be used to transfer signals between non-electrical-connection stacked dies
Data Source
AI summary
The present disclosure relates to a microelectronics package with a self-aligned stacked-die assembly and a process for making the same. The disclosed microelectronics package includes a module substrate, a first die with a first coupling component, a second die with a second coupling component, and a first mold compound. The first die is attached to the module substrate. The first mold compound resides over the module substrate, surrounds the first die, and extends above an upper surface of the first die to define a first opening. Herein, the first mold compound provides vertical walls of the first opening, which are aligned with edges of the first die in X-direction and Y-direction. The second die is stacked with the first die and in the first opening, such that the second coupling component is mirrored to the first coupling component.