Vacuum Venting Enhances the Replication of Nano/Microfeatures in Micro-Injection Molding Process

Choi, Seong Ying; Zhang, Nan; Toner, J. P.; Dunne, Greg; Gilchrist, Michael D.

doi:10.1115/1.4032891

Cited by 6 publications

(2 citation statements)

References 14 publications

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“…Baruffi et al 16 identified that mold temperature and packing pressure significantly influence the outer ring diameter of microlenses, whereas the inner ring diameter is mainly affected by mold temperature and melt temperature. Gilchrist et al 17 concluded that the replication quality of high aspect ratio microstructures could be effectively improved by using vacuum aeration. Orth et al 18 found that the use of coated steel molds resulted in higher molding efficiency and 20% ~ 30% improvement in replication quality.…”

Section: Introductionmentioning

confidence: 99%

Enhancing structural replication of microfluidic chips: Parameter optimization and mold insert modification

Wang,

Weng,

Fei

et al. 2024

Polymer Engineering & Sci

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The demolding process in micro‐injection molding constitutes a critical phase, exerting a decisive influence on the quality of polymer microstructures. In this study, the demolding forces of PMMA microfluidic chips were measured under different demolding temperatures, packing pressures, and demolding speeds by using pure nickel (Ni) mold insert. The dimensional deviations of the microchannels with different aspect ratios were analyzed. In addition, the effect of mold insert modification on the demolding force was further analyzed. The results showed that the effect of demolding temperature on the demolding force was the most significant, and the peak demolding force decreased with the decrease in temperature. The width of the microchannels increased and the depth decreased after demolding, while the opposite results were observed for the micro‐mixing structures. However, the dimensional deviation of the micro‐mixing structures was larger than that of the microchannels. Using the optimal molding parameters, the peak demolding force could be reduced from 114.0 N at 110°C to 47.0 N, a decrease of 58.8%. It is noteworthy that, when the microchannel was narrower than 100 μm, achieving precise replication of microchannel dimensions became progressively more challenging as the microchannel width decreased. Using the Ni‐WS2 mold insert with low surface energy and low friction coefficient, the demolding force could be further reduced by 38.3%. The effect of the molding quality of microfluidic chip microstructures on the mixing performance of heavy metals was demonstrated by micro‐mixing experiments.Highlights Demolding temperature crucially affects microstructure dimensions. Optimal parameters and modified mold insert reduce demolding force by 38.3%. Dimensional deviation increases with the increase of microchannel aspect ratio. Optimized microfluidic chip enhances Co2+ chemiluminescence by 6.42%.

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Section: Introductionmentioning

confidence: 99%

Enhancing structural replication of microfluidic chips: Parameter optimization and mold insert modification

Wang,

Weng,

Fei

et al. 2024

Polymer Engineering & Sci

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“…Vacuum venting is another type of technology that can be applied to µIM to improve part outcome and thus reduce energy costs. Ying Choi et al [8] have shown that by vacuum venting during the injection phase of the µIM process can create more defined features over larger areas and increased depths. Depth replication was improved by 1.33-7.52% and 0.88-5.94% by varying the vacuum pressure and time respectively.…”

Section: Introduction*mentioning

confidence: 99%

Investigation of the Integrity of aC:H Coatings on Stainless Steel Micro-Moulds during Thermal Cycling

Griffiths

Rees

Llewelyn

et al. 2018

J. Coat. Sci. Technol.

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Micro-injection moulding (µIM) is a key technology for scaling down larger geometry components and can include functional features at the micrometre scale and as far as the sub-micrometre length scale. Thermal cycling of amorphous hydrogenated carbon (aC:H) coated Stainless Steel (SS) has been investigated to simulate long-term micro-injection moulding (µIM) wearing and damage. Micro indentations and cracks were made into the mould and predictions of the crack behaviour were made using thermal expansion models. Validation of the results was performed with multiple heating and cooling cycles along with hardness measurements of the damage to the coating. The undamaged surfaces showed no major deformation but the cracks were shown to propagate and change in behaviour. The first two heat cycles of the testing had the most significant effect on the substrate with varying thermal expansions of materials being the main cause. The aC:H is shown to have excellent properties for mould tool applications but delamination could occur in areas susceptible to damaged and periodic surface inspection will be required preserve tool life.

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Vacuum-Assisted Micro Injection Molding

Lucchetta,

Sorgato,

Masato

2018

Micro Injection Molding

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Vacuum Venting Enhances the Replication of Nano/Microfeatures in Micro-Injection Molding Process

Cited by 6 publications

References 14 publications

Enhancing structural replication of microfluidic chips: Parameter optimization and mold insert modification

Enhancing structural replication of microfluidic chips: Parameter optimization and mold insert modification

Investigation of the Integrity of aC:H Coatings on Stainless Steel Micro-Moulds during Thermal Cycling

Vacuum-Assisted Micro Injection Molding

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