Moisture Impermeable Layer for Semiconductor Substrate Void Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor device assemblies face void formation issues due to moisture absorption in high humidity environments, leading to inefficiencies in assembly processes and increased costs, particularly when using non-conductive film (NCF), thermo-compression bonding with flux and capillary underfill, and die attach film.
Innovation Solution
A moisture impermeable layer is introduced between the substrates, composed of materials like polyimides, parylene, or epoxy-acrylates, to prevent moisture from reaching the bonding areas, thereby inhibiting void formation. This layer can be deposited using techniques such as 3D printing or screen printing, ensuring it does not cover electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If substrates are assembled in a high humidity environment, then electrostatic discharge protection is improved, but moisture absorption increases causing void formation in NCF
Solution Approach 1:
The substrate surface is segmented into different functional zones: a moisture impermeable layer is applied to specific regions where void formation is problematic, while other regions remain exposed to humidity for electrostatic discharge protection. This selective segmentation allows simultaneous achievement of both goals.
Solution Approach 2:
Different surface properties are applied to different locations on the substrate. The moisture impermeable layer provides local moisture barrier properties in critical bonding areas, while other areas maintain hydrophilic properties for moisture absorption and electrostatic discharge protection. This local differentiation resolves the contradiction between preventing voids and maintaining ESD protection.
2Manufacturing precision
If substrates are baked for extended periods to remove moisture, then void formation is reduced, but assembly cost and time increase
Solution Approach 1:
The moisture impermeable layer is applied in advance to specific substrate regions before assembly, pre-preventing moisture migration to bonding interfaces. This preliminary protective action eliminates the need for extended post-assembly baking processes, reducing both time and cost while preventing void formation.
Solution Approach 2:
The moisture impermeable layer extracts or removes the harmful moisture migration pathway from the substrate structure, preventing moisture from reaching the NCF bonding interface. This extraction of the moisture transport mechanism eliminates void formation without requiring extended thermal processing.
3Manufacturing precision
If substrates are baked to remove moisture, then void formation is prevented, but substrates re-absorb moisture requiring rapid assembly
Solution Approach 1:
The substrate is segmented into moisture-sensitive bonding areas covered by the impermeable layer and other areas that can safely absorb moisture. This segmentation allows substrates to be assembled at normal speeds without rapid assembly requirements, as the impermeable layer prevents moisture from reaching critical bonding interfaces regardless of assembly timing.
4Manufacturing precision
If moisture impermeable layer is applied to entire substrate, then void formation is eliminated, but electrical connections may be compromised
Solution Approach 1:
The moisture impermeable layer is applied selectively to specific regions of the substrate surface, creating local moisture barrier properties only where needed for void prevention. Electrical connection areas are excluded from the impermeable layer application, maintaining their required electrical and moisture interaction properties. This local differentiation eliminates voids while preserving electrical connection integrity.
Solution Approach 2:
The substrate surface is segmented into moisture-barrier zones and electrical connection zones. The moisture impermeable layer is applied only to the bonding areas where void prevention is critical, while electrical connection areas remain uncovered or have different surface properties, ensuring both functions are optimized independently.
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 moisture impermeable layer effectively reduces void formation in non-conductive films and underfill materials, enhancing the assembly process by maintaining substrate dryness and reducing assembly time and costs, while maintaining electrostatic discharge protection.
Implementation Method 1
a moisture impermeable layer is introduced between the substrates, composed of materials like polyimides, parylene, or epoxy-acrylates, to prevent moisture from reaching the bonding areas
Implementation Method 2
capillary underfill (CUF) may be dispensed next to the semiconductor bond line so that the capillary effect pulls the CUF into the bond line until it is full
Data Source
AI summary
A semiconductor device, semiconductor device assembly, and method of forming a semiconductor device assembly that includes moisture impermeable layer. The assembly includes a first substrate and a second substrate electrically connected to a surface of the first substrate. The assembly includes a layer between the two substrates with the moisture impermeable layer between the layer and the surface of the first substrate. The layer may be non-conductive film, die attach film, capillary underfill, or the like. A portion of the surface of the first substrate may include a solder mask between the moisture impermeable layer and the first substrate. The moisture impermeable layer prevents, or at least inhibits, moisture within the first substrate from potentially creating voids in the layer. The moisture impermeably layer may be a polyimide, a polyimide-like material, an epoxy, an epoxy-acrylate, parylene, vinyltriethoxysilane, or combination thereof. The moisture impermeable layer may have a high electrical resistance.