Volumetric effective cure shrinkage measurement of dual curable adhesives by fiber Bragg grating sensor

Phansalkar, Sukrut Prashant; Kim, Changsu; Han, Bongtae; Gromala, Przemyslaw Jakub

doi:10.1007/s10853-020-04716-1

Cited by 11 publications

(6 citation statements)

References 11 publications

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“…The ECS can be determined from Δλ B when the Poisson's ratio and the modulus of the polymer are known. 8,9 It was also shown in Ref. [11] that the curing-induced radial stress of the fiber is much smaller than the corresponding axial stress, which makes the loading 2) is reduced to 11 :…”

Section: Fbg-based Methodsmentioning

confidence: 95%

“…The generalized plane strain solution for the stress components of the FBG sensor, caused by the ECS, was first derived by Wang et al 11 It was later utilized to define the relationship between the BW shifts and the ECS. 4,8,9 The relationship can take a form of…”

Section: Fbg-based Methodsmentioning

confidence: 99%

“…The behavior of a typical polymer system during curing is illustrated in Figure 3. 8 where the x-axis shows an arbitrary time scale, and the y-axis represents two polymer properties associated with curing (cure shrinkage, ε(t) and modulus, E(t)), normalized by their final values, ε ∞ and E ∞ , obtained at full-cure. 9 The cure shrinkage is proportional to the extent of cure, and the modulus evolves non-linearly with time.…”

Section: Effective Cure Shrinkagementioning

confidence: 99%

“…These advantages were exploited to measure the residual stress/strain in composite materials, 6 and the ECS values of various materials. 4,7,8 For the ECS measurement, an FBG sensor is embedded in a specimen, and thus, a mold to contain uncured polymers in a liquid state is required. The most critical challenge encountered during the measurement is to negate the effect of the mold on the ECS.…”

Section: Introductionmentioning

confidence: 99%

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Measurement of effective cure shrinkage of epoxy‐based molding compound by fiber Bragg grating sensor using two‐stage curing process

Kim

Phansalkar

Lee

et al. 2021

J of Applied Polymer Sci

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Cure shrinkage accumulated only after the gel point is known as effective cure shrinkage (ECS), which produces residual stresses inside molded components.The ECS of an epoxy-based molding compound (EMC) is measured by an embedded fiber Bragg grating (FBG) sensor. Under a typical molding condition, a high mold pressure inherently produces large friction between EMC and mold inner surfaces, which hinders EMC from contracting freely during curing. A two-stage curing process is developed to cope with the problem. In the first stage, an FBG sensor is embedded in EMC by a molding process, and the FBG-EMC assembly is separated from the mold at room temperature. The molded specimen is heated to a cure temperature rapidly in the second stage using a constraint-free curing fixture. Several technical issues have to be taken into considerations to ensure that (1) EMC does not pass the gel point before it reaches the cure temperature, and (2) EMC cures uniformly around the FBG during measurements. The ECS of an EMC with a filler content of 88 wt% is measured by the proposed method, and its value is 0.077%. The repeatability of the proposed method is corroborated by the results of a duplicate test.

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Section: Fbg-based Methodsmentioning

confidence: 95%

Section: Fbg-based Methodsmentioning

confidence: 99%

Section: Effective Cure Shrinkagementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Measurement of effective cure shrinkage of epoxy‐based molding compound by fiber Bragg grating sensor using two‐stage curing process

Kim

Phansalkar

Lee

et al. 2021

J of Applied Polymer Sci

Self Cite

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“…The ECS of the EMC was measured in the CCC using TMA. The load was set to the minimum value of 0.001 N, at which no resin flow was caused by pressure. , The ECS was determined by the dimension change in the gelation temperature according to the following equation: ε E C S = H Gelation 0.25em curing − normalH Gelation 0.25em cured H Gelation 0.25em curing where ε ECS is the ECS of the EMC, H Gelation curing is the initial thickness at gelation in the curing process, and H Gelation cured is the thickness at gelation after curing. The calculated ε ECS represents isotropic ECS because EMC is a randomly distributed silica (spherical shape) reinforced epoxy composite material.…”

Section: Methodsmentioning

confidence: 99%

Electronic Packaging Enhancement Engineered by Reducing the Bonding Temperature via Modified Cure Cycles

Park

Kim

et al. 2023

ACS Appl. Mater. Interfaces

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Semiconductor packaging continues to reduce in thickness following the overall thinning of electronic devices such as smartphones and tablets. As the package becomes thinner, the warpage of the semiconductor package becomes more important due to the reduced bending stiffness and driven by thermal residual stresses and thermal expansion mismatch during the epoxy molding compound (EMC) curing to create the package. To address this packaging reliability issue, in this study, we developed a modified cure cycle that adds a rapid cooling step to the conventional cure cycle (CCC) to enhance the reliability of the EMC molded to a copper substrate (EMC/Cu bi-layer package) by lowering the bonding temperature of the EMC/Cu bi-layer package. Modeling of the package via Timoshenko theory including effective cure shrinkage allowed the rapid cooling step to be quantified and confirmed via experiments. The modified cure cycle resulted in a 26% reduction in residual strain, a 27% reduction in curvature, and a 40% increase in peel strength compared to the CCC, suggesting that this is an effective new method for managing warping effects in such packaged structures.

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Determination of residual stresses in a single FBG fiber/epoxy composite system

Khadka

Kumosa

Hoffman

2022

Composites Science and Technology

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Volumetric effective cure shrinkage measurement of dual curable adhesives by fiber Bragg grating sensor

Cited by 11 publications

References 11 publications

Measurement of effective cure shrinkage of epoxy‐based molding compound by fiber Bragg grating sensor using two‐stage curing process

Measurement of effective cure shrinkage of epoxy‐based molding compound by fiber Bragg grating sensor using two‐stage curing process

Electronic Packaging Enhancement Engineered by Reducing the Bonding Temperature via Modified Cure Cycles

Determination of residual stresses in a single FBG fiber/epoxy composite system

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