Screen-Printed Epoxy Spacers for Complex Semiconductor Stacking
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Solution Overview
Problem
Conventional silicon spacers used in semiconductor device assemblies are costly, prone to contamination, and limited in shape due to mechanical singulation methods, which restrict their ability to provide mechanical support for diverse semiconductor devices with varying plan areas and thicknesses.
Innovation Solution
Epoxy spacers are formed on package substrates using screen-printing with a three-dimensional stencil, allowing for complex shapes and planarization through a gang-pressing operation to address shape limitations and cost issues, while ensuring mechanical support for stacked semiconductor devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional silicon spacers are used, then mechanical support is provided, but cost increases and contamination risks arise
Solution Approach 1:
The patent replaces expensive silicon spacers with inexpensive epoxy-based spacers that are applied as a coating and then cured. This disposable-like approach uses a low-cost material that can be easily applied and removed or replaced without generating the same contamination issues as silicon singulation
Solution Approach 2:
The patent replaces the mechanical singulation process for creating silicon spacers with a chemical/coating-based approach. Instead of mechanically cutting and handling silicon pieces, the invention uses screen printing or dispensing to apply epoxy material that is then cured to form the spacer structure, eliminating mechanical contamination sources
2Reliability
If conventional silicon spacers are used, then mechanical support is provided, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive silicon spacers with inexpensive epoxy-based spacers that are applied as a coating and then cured. This disposable-like approach uses a low-cost material that can be easily applied and removed or replaced without generating the same contamination issues as silicon singulation
Solution Approach 2:
The patent changes the material parameter from silicon to epoxy-based materials, which fundamentally alters the cost structure. The epoxy materials can be applied in thin layers and cured in place, eliminating the need for expensive silicon wafer processing and singulation steps
3Reliability
If conventional silicon spacers are used, then mechanical support is provided, but shape flexibility is limited
Solution Approach 1:
The patent uses epoxy-based materials that can be applied as thin films or coatings through screen printing or dispensing. These materials can conform to complex substrate geometries and be cured in place to create spacers with virtually any shape, unlike rigid silicon pieces that must be mechanically cut
Solution Approach 2:
The patent changes the material parameter from silicon to epoxy-based materials, which fundamentally alters the cost structure. The epoxy materials can be applied in thin layers and cured in place, eliminating the need for expensive silicon wafer processing and singulation steps
4Shape
If screen-printing with three-dimensional stencil is used, then complex shapes are enabled, but process complexity increases
Solution Approach 1:
The patent introduces a three-dimensional stencil as an intermediary tool that simplifies the creation of complex spacer shapes. The stencil acts as a template or mask that guides the screen-printing or dispensing process, allowing complex geometries to be created without complex processing steps
Solution Approach 2:
The three-dimensional stencil is prepared in advance with the desired spacer geometry encoded in its structure. This preliminary action of creating the stencil allows subsequent spacer formation to be a simple material deposition process rather than a complex shaping process
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 epoxy spacers provide reliable mechanical support, enabling the stacking of larger devices over smaller ones without mechanical stress, reducing costs and contamination risks, and allowing for diverse and complex shapes that conventional silicon spacers cannot accommodate.
Implementation Method 1
epoxy spacers formed on package substrates by screen-printing
Implementation Method 2
The spacers can be readily formed in various complex (e.g., concave, irregular, etc.) polygonal and/or curved shapes adapted to the needs of various assembly configurations
Implementation Method 3
The planarity of a single epoxy spacer, and/or the co-planarity of multiple epoxy spacers, can be achieved by a pressing operation
Data Source
AI summary
A method of making a semiconductor device assembly is provided. The method comprises attaching a first semiconductor device to an upper surface of a substrate and disposing a stencil over the upper surface of the substrate. The stencil includes (i) an opening and (ii) a cavity in which the first semiconductor device is disposed. The method further comprises screen-printing an epoxy material into the opening and onto the upper surface of the substrate, removing the stencil, and planarizing an upper surface of the epoxy material to form an epoxy spacer.