microstructures

W. Michaeli (a), F. Klaiber (a), S. Scholz (b)

(a) Institute of Plastics Processing, RWTH Aachen University, Aachen, Germany
(b) The Manufacturing Engineering Centre, Cardiff University, Cardiff, CF24 3AA, UK

Abstract

Telecommunication, information and medical industries have a high growth potential. A key technology for those industries is the replication of microstructures. Precise microstructured parts with functional surfaces can be produced economically by injection moulding. The whole process chain (thermal mould condition, moulding, demoulding, measurement and analysis) must be analysed carefully to ensure the highest precision and reliability. To enable the precise production of such structures fundamental studies were conducted at the Institute of Plastics Processing (IKV). The studies considered several polymers (PMMA, POM) on the one side and various test structures on the other side. In addition an innovative external inductive heating unit was analysed and implemented into the process to heat the cavity surface efficiently. Using this technique cavity surface temperature increase rates of up to 60 K/s have been achieved. A pyrometer was implemented for contact less instant temperature measurement, and controller was used to realise preset cavity temperatures by regulating the inductor power. With the dynamic inductive heating system the moulding accuracy of the microstructures could be increased drastically. The final step of the process chain comprises of the measurement and analysis of the microstructured moulded parts. To analyse the microscopic deviation between the mould cavity and the surface of the moulded part scanning electron microscopy (SEM) and white light interferometry (WLI) was used.

D. Ulieru (a), Alina Matei (b), Elena Ulieru (c), A. Tantau (c), Florin Babarada (d)

(a) ROMES S.A., 126A, Iancu Nicolae Str., Bucharest, 72996, ROMANIA
(b) National Institute for Research and Development in Microtechnologies, 32B,Erou Iancu Nicolae Str., Bucharest, 077190, ROMANIA
(c) SITEX 45 SRL, 114, Ghica Tei Blvd., bl. 40, ap. 2, Dept. 2, Bucharest 72235, ROMANIA
(d) “Politehnica” University of Bucharest, Splaiul Independentei Str., No. 313, Bucharest 060042, ROMANIA

Abstract

The strong evolution of electronic packaging in the field of high performance hand held electronic products involves, from the fabrication point of view, to manufacture small, lightweight, reliable and, very important too, cost effective electronic modules. In the last years new techniques and technologies for production of rigid/flexible MCMtype multilayer were introduced. The manufacturers of laminate substrates are being challenged to realize boards with very good electrical and mechanical properties. In the past the biggest issues regarding vias and via capture pad sizes were only solderability and manufacturability. Today the vias density is also an important electrical issue. The more vias on a board are presented, the more discontinuities into PCB/MCM passive interconnection structure are placed. For High Density Interconnection (HDI) circuits design one solution is to reduce the via hole and the via capture pad, but still maintain manufacturability at board fabrication stage.The most indicated solution is to use UV laser microprocessing for HDI production.

H. N. Hansen, U. A. Theilade
Department of Manufacturing Engineering and Management, Technical University of Denmark, Building 427, Produktionstorvet, DK-2800 Kgs. Lyngby, Denmark

Abstract

In recent years polymer components with surface microstructures have been in rising demand for applications such as lab-on-a-chip and optical components. Injection moulding has proven to be a feasible and efficient way to manufacture such components. In injection moulding the mould surface topography is transcribed onto the plastic part through complex mechanisms. This replication however, is not perfect, and the replication quality depends on the plastic material properties, the topography itself, and the process conditions. This paper describes and discusses an investigation of injection moulding of surface microstructures. Emphasis is put on the ability to replicate surface microstructures under normal injection moulding conditions, notably with low cost materials at low mould temperatures. The replication of surface microstructures in injection moulding has been explored for Polypropylene at low mould temperatures. The process conditions were varied over the recommended process window for the material. The geometry of the obtained structures was analyzed. Evidence suggests that step height replication quality depends linearly on structure width in a certain range. Further it was found that in this range, the replication quality depends strongly on process conditions. It was concluded that the achieved step height varies linearly with the mould groove width.