Wafer-level BCB bonding using a thermal press for microfluidics

Benzocyclobutene (BCB) is a thermosetting polymer that can form microfluidics and bond top and bottom layers of the microfluidics at the same time, and yields high repeatability and high bonding strength. This paper reports using photosensitive BCB to fabricate microfluidics and to bond with a thermal press for 4 in. wafers. By optimizing the parameters for pattern development and using a three-stage temperature and pressure increment BCB bonding, we realize the whole wafer glass–Si or glass–glass bonding in thermal press without any crack. The wafer-level bonding shows a bonding percentage above 70%, a tensile stress above 4.94 MPa, and a bonding repeatability over 95%. Furthermore, the bonding is compatible with thick electrode integration, that microfluidics with 380 nm thick electrodes underneath can be well-bonded. Our bonding method much reduces the cost compared with bonding BCB in a wafer bonding machine. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Structural characterization of polypropylene/poly(lactic acid) bicomponent meltblown

The bicomponent meltblown process offers to associate two polymers in the same fiber generating fibrous media with new properties. In this study, we associate polypropylene (PP) and poly(lactic acid) (PLA), from renewable sources, polymers. The influence of primary air flow rate and the structural properties of the PP/PLA bicomponent meltblown are compared to PP and PLA monocomponent meltblown. The structural properties include fiber morphology and diameter, packing density, permeability, thermal shrinkage and crystallization. The results relate that the PP/PLA bicomponent meltblown fiber diameters are thinner than those of PLA monocomponent. Moreover, it has higher resistance to thermal shrinkage compared to PP monocomponent meltblown. The packing density and permeability are not affected by the association of PP and PLA due to low crimp effect. Two different filament formations of PP/PLA bicomponent meltblown at low and high primary air flow rate have also been observed. Lastly, this study illustrates that PP and PLA association is viable, showing the production of PP/PLA bicomponent microfiber and limited thermal shrinkage at high temperature. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44540.