A batch-mode assembly and packaging technology for 3-axis tri-fold inertial measurement units
This paper reports a batch-mode generic 3-D precision assembly and wafer-level packaging technology for 3-axis tri-fold inertial measurement units (IMUs) using silicon mounting jig wafers with embedded vacuum channels. This approach allows use of optimized single-axis IMUs without manufacturing and structural constraints of forming 3-axis in a chip, and improving the overall yield by testing the chips prior to 3-D assembly. The 3-D chip assembly is performed by a controlled sequence of vacuum through the channels and bottom access holes, ambient pressurization, and raise of temperature to form permanent rigid tri-fold bond to the jig wafer.
3D stack method for micro-PNT based on TSV technology
On the benefit of the deeply development of MEMS and inertial instrument technology, the novel micro technology for positioning, navigation and timing (μΡΝΤ) becomes the substitution of GPS technology, and is the one of the most popular research area. The μ PNT unit volume can be pressed obviously by employing 3D stack technology after MEMS components are finished, and through silicon vias (TSV) technology connects the pins inside the stack with outside ones. 3D stack and TSV technology improves the reliability and high G-shock survival ability of μPNT unit. The silicon on glass (SOG) style is one of the most common structure for MEMS sensor, and the special TSV technology aimed at SOG is researched in this paper to support the SOG structure based μPNT unit.
Expansion without equity: An analysis of current policy on access to higher education in Brazil
Access to higher education in Brazil is to a large extent restricted to the higher socio-economic groups. Public universities have limited places and entry is determined by highly competitive exams, thereby excluding those who have not had a high quality secondary education or attended an expensive preparatory course. There has been considerable growth in the private sector to absorb the excess demand, but the majority of Brazilians cannot afford the fees. This paper develops a concept of equity in higher education in which, firstly, there should be sufficient places in the system as a whole and, secondly, all people should have a fair opportunity of attending the university of their choice regardless of socio-economic background. Recent efforts to expand access are analysed, including incentives for the growth of private universities, student loans and the new Prouni initiative, in which private institutions provide free places to low-income students in return for tax exemptions. While these initiatives have the potential to increase the total number of places, they will not lead to an equitable expansion, as disadvantaged students will still be confined to courses of lower quality or with lower subsequent value on the employment market. Initiatives aimed at the public sector such as the introduction of quotas and changes to entry examinations are also discussed. Finally, some implications for future policy development are outlined.