Underfill Material Non-Bingham Fluidity Voidless Packaging
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Solution Overview
Problem
Conventional underfill films used in semiconductor chip packaging often result in insufficient air removal during packaging, leading to voids due to their low melt viscosity and lack of non-Bingham fluidity, which affects solder connectivity.
Innovation Solution
An underfill material comprising epoxy resin, acid anhydride, acrylic resin, and organic peroxide is applied to semiconductor chips with solder-tipped electrodes, exhibiting non-Bingham fluidity between 60° C. and 100° C. and a storage modulus within specific ranges, enabling voidless packaging and improved solder bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional underfill films with low melt viscosity are used, then solder connectivity is improved, but air removal during packaging becomes insufficient leading to voids
Solution Approach 1:
The patent changes the rheological parameters of the underfill material by specifying a storage modulus G' between 10^4 Pa and 10^5 Pa and loss modulus G'' between 10^3 Pa and 10^4 Pa, creating a specific viscosity ratio G''/G' of 0.01 to 1.0. This parameter optimization allows the material to maintain low enough viscosity for solder connectivity while having sufficient viscosity control to enable air removal during packaging, resolving the contradiction between solder connectivity and void prevention
Solution Approach 2:
The patent uses a composite material system consisting of epoxy resin and acrylic resin in specific proportions (epoxy resin 70-99.9 mass%, acrylic resin 0.1-30 mass%). This composite formulation combines the advantages of both resin types to achieve the targeted rheological properties that simultaneously enable good solder connectivity and effective air removal during the packaging process
2Productivity
If underfill film is applied to wafer in advance (pre-applied underfill film), then mounting process is shortened, but void formation occurs due to insufficient air removal
Solution Approach 1:
The patent optimizes the rheological parameters (storage modulus G' of 10^4-10^5 Pa, loss modulus G'' of 10^3-10^4 Pa, and viscosity ratio G''/G' of 0.01-1.0) of the pre-applied underfill film material. These parameter changes enable the film to maintain appropriate viscosity during the shortened mounting process while still allowing sufficient air removal, thus achieving both high productivity and voidless packaging
3Reliability
If underfill material has low storage modulus (10^4 Pa or less), then solder connectivity is improved, but non-Bingham fluidity is lost resulting in insufficient air removal
Solution Approach 1:
The patent precisely controls the storage modulus G' to be between 10^4 Pa and 10^5 Pa, and loss modulus G'' to be between 10^3 Pa and 10^4 Pa, achieving a specific viscosity ratio G''/G' of 0.01 to 1.0. This optimized parameter range maintains the material's ability to flow for good solder connectivity while preserving non-Bingham fluidity characteristics that enable effective air removal during packaging
Solution Approach 2:
The composite formulation of epoxy resin (70-99.9 mass%) and acrylic resin (0.1-30 mass%) creates a material system that exhibits both low storage modulus for solder connectivity and non-Bingham fluidity for air removal. The synergistic interaction between the two resin types achieves the dual requirement of good solder wetting and sufficient air evacuation capability
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 underfill material achieves voidless packaging and excellent solder connection properties by maintaining non-Bingham fluidity and appropriate storage modulus, ensuring effective bonding without void formation.
Implementation Method 1
the underfill material contains an epoxy resin, an acid anhydride, an acrylic resin and an organic peroxide
Implementation Method 2
the underfill material contains an epoxy resin, an acid anhydride, an acrylic resin and an organic peroxide
Implementation Method 3
the underfill material exhibits non-Bingham fluidity at a temperature ranging from 60° C. to 100° C.
Implementation Method 4
The semiconductor chip and substrate are thermally compressed together, electrical conduction is ensured using metallic bonding of solder bumps
Data Source
AI summary
An underfill film material and a method for manufacturing a semiconductor device using the same which enables voidless mounting and favorable solder bonding properties are provided. An underfill material is used which contains an epoxy resin, an acid anhydride, an acrylic resin and an organic peroxide, the underfill material exhibits non-Bingham fluidity at a temperature ranging from 60° C. to 100° C., a storage modulus G′ measured by dynamic viscosity measurement has an inflection point in an angular frequency region below 10E+02 rad/s, and the storage modulus G′ in the angular frequency below the inflection point is 10E+05 Pa or more and 10E+06 Pa or less. This enables voidless packaging and excellent solder connection properties.