Towards the Automated Coverlay Assembly in FPCB Manufacturing: Concept and Preliminary Tests

AbstractIn modern electronics, flexible and rigid-flex PCBs are largely used due to their intrinsic versatility and performance, allowing to increase the available volume, or enabling connection between unconstrained components. Rigid-flex PCBs consists of rigid board portions with flexible interconnections and are commonly used in a wide variety of industrial applications. However, the assembly process of these devices still has some bottlenecks. Specifically, they require the application of cover layers (namely, coverlays), to provide insulation and protection of the flexible circuits. Due to the variability in planar shape and dimensions, the coverlay application is still performed manually, requiring troublesome manipulation steps and resulting in undetermined time-cycle and precision.This paper aims at the improvement of the industrial process currently performed, by proposing an approach for the automation of Kapton coverlay manipulation and application. Since these products are commercially provided as a film with a protective layer to be removed, the peeling issue is addressed, representing a challenging step of the automated process; the results of a systematic series of tests, performed in order to validate the peeling strategy, are reported in the paper. The overall assembly strategy relies on the development of a customized multi-hole vacuum gripper, whose concept is presented and contextualized in the proposed assembly process by outlining a suitable workcell architecture

Microstructural characterization and in vitro bioactivity of porous glass-ceramic scaffolds for bone regeneration by synchrotron radiation X-ray microtomography

One of the key purposes of bone tissue engineering is the development of new biomaterials that can stimulate the body's own regenerative mechanism for patient's anatomical and functional recovery. Bioactive glasses, due to their versatile properties, are excellent candidates to fabricate porous 3-D architectures for bone replacement. In this work, morphological and structural investigations are carried out on Bioglass\uae- and CEL2-derived scaffolds produced by sponge replication (CEL2 is an experimental glass developed at Politecnico di Torino). Synchrotron radiation X-ray microtomography is used to study the samples 3-D architecture, pores size, shape, distribution and interconnectivity, as well as the growth kinetics on scaffolds struts of a newly formed apatitic phase during in vitro treatment in simulated body fluid, in order to describe from a quantitative viewpoint the bioactive potential of the analyzed biomaterials. An accurate comparison between architectural features and bioactive behaviour of Bioglass\uae- and CEL2-derived scaffolds is presented and discussed

Micro-CT studies on 3-D bioactive glass-ceramic scaffolds for bone regeneration

The aim of this study was the preparation and characterization of bioactive glass-ceramic scaffolds for bone tissue engineering. For this purpose, a glass belonging to the system SiO2-P2O5-CaO-MgO-Na2O-K2O (CEL2) was used. The sponge-replication method was adopted to prepare the scaffolds; specifically, a polymeric skeleton was impregnated with a slurry containing CEL2 powder, polyvinyl alcohol (PVA) as a binding agent and distilled water. The impregnated sponge was then thermally treated to remove the polymeric phase and to sinter the inorganic one. The obtained scaffolds possessed an open and interconnected porosity, analogous to cancellous bone texture, and with a mechanical strength above 2 MPa. Moreover, the scaffolds underwent partial bioresorption due to ion-leaching phe- nomena. This feature was investigated by X-ray computed microcomputed tomography (micro-CT). Micro-CT is a three-dimensional (3- D) radiographic imaging technique, able to achieve a spatial resolution close to 1 lm3. The use of synchrotron radiation allows the selected photon energy to be tuned to optimize the contrast among the different phases in the investigated samples. The 3-D scaffolds were soaked in a simulated body fluid (SBF) to study the formation of hydroxyapatite microcrystals on the scaffold struts and on the internal pore walls. The 3-D scaffolds were also soaked in a buffer solution (Tris-HCl) for different times to assess the scaffold bioresorp- tion according to the ISO standard. A gradual resorption of the pores walls was observed during the soakings both in SBF and in Tris- HC

In vitro biocompatibility of 45S5 Bioglass(r)-derived glass-ceramic scaffolds coated with poly(3-hydroxybutyrate)

The aim of this work was to study the in vitro biocompatibility of glass-ceramic scaffolds based on 45S5 Bioglass(R), using a human osteosarcoma cell line (HOS-TE85). The highly porous scaffolds were produced by the foam replication technique. Two different types of scaffolds with different porosities were analysed. They were coated with a biodegradable polymer, poly(3-hydroxybutyrate) (P(3HB)). The scaffold bioactivity was evaluated by soaking in a simulated body fluid (SBF) for different durations. Compression strength tests were performed before and after immersion in SBF. These experiments showed that the scaffolds are highly bioactive, as after a few days of immersion in SBF a hydroxyapatite-like layer was formed on the scaffold's surface. It was also observed that P(3HB)-coated samples exhibited higher values of compression strength than uncoated samples. Biocompatibility assessment was carried out by qualitative evaluation of cell morphology after different culture periods, using scanning electron microscopy, while cell proliferation was determined by using the AlamarBlue(TM) assay. Alkaline phosphatase (ALP) and osteocalcin (OC) assays were used as quantitative in vitro indicators of osteoblast function. Two different types of medium were used for ALP and OC tests: normal supplemented medium and osteogenic medium. HOS cells were seeded and cultured onto the scaffolds for up to 2 weeks. The AlamarBlue assay showed that cells were able to proliferate and grow on the scaffold surface. After 7 days in culture, the P(3HB)-coated samples had a higher number of cells on their surfaces than the uncoated samples. Regarding ALP- and OC-specific activity, no significant differences were found between samples with different pore sizes. All scaffolds containing osteogenic medium seemed to have a slightly higher level of ALP and OC concentration. These experiments confirmed that Bioglass(R)/P(3HB) scaffolds have potential as osteoconductive tissue engineering substrates for maintenance and normal functioning of bone tissue. Copyright (C) 2009 John Wiley & Sons, Ltd

Full-mesh optical backplane with modular fiber ribbon-based sub-circuits

A modular, scalable and full-mesh bandwidth-upgradable optical interconnection between optoelectronic boards is guaranteed thanks to an optimized layout of standard MM fiber ribbons which divides the overall backplane into independent optical sub-circuits