Micro-injection moulding of high precision optical coupling components

Aantal studenten: 1 of 2
Aantal masterproeven: 1
Promotor 1: Erwin Bosman
Promotor 2: Ludwig Cardon
Begeleider 1: Lothar Mader

Contactpersoon: Erwin Bosman

Trefwoorden: automation, coupling, fiber, integration, plastic, micro-injection moulding

Problem statement:

Nowadays, electronic and optical systems are becoming increasingly smaller. This allows integrating a large amount of functionality in a small package, e.g. smartphones. Additionally, more and more electronic systems are being replaced by optical systems. Examples can be found in sensing (optical sensors can be much more sensitive than electrical sensors) or telecommunication in which optical fibers enable Terabit per second data rates. Also for optical systems, integration and miniaturization plays an important role since it will allow for example higher bandwidth, more sensors or more functionality per unit area.

However, when optical structures reduce in size, coupling the light in and out becomes increasingly challenging. At the Cmst research group (Elis department, http://www.cmst.be), various technologies are available to integrate light sources and detectors in very thin (~40 micron) foils, so that they become even flexible. Furthermore, polymer processing technologies enable us to fabricate very small and single mode optical waveguides (typical dimensions between 1 and 10 micron). The challenge is to couple these light sources and detectors to these optical waveguides and optical fibers, this coupling is called pigtailing.  Traditional methods for pigtailing are either by passive alignment using injection moulded connectors and adaptors fitting into each other or by active alignment were the optical power coupled into the fiber has to be measured during pigtailing. The first method is however not accuracte enough for these small dimension waveguides. The second is much more accurate but extremely costly due to the sequential process of the position tuning. So the optical telecommunication sector is really looking for some groundbreaking innovations in this field.

One of the most promising solutions for this problem is the extension of the existing “coarse” injection moulding technology towards high precision micromoulding. This extension asks for innovative add-ons to the traditional process, like the introduction of compression molding, variotherm, IR mold heating and of course the fabrication of high precision molds.

Goals of the thesis

Two research groups of the association Ugent , being CMST and CPMT, have joined forces to take this step forward in injection molding technology. CMST has installed a state-of-the-art micro injection machine of Wittmann-Battenfeld in their cleanrooms enabling high precision on the pressure, temperature, dosing  and injection speed of the polymer. Moreover, CMST has a broad knowhow and tool park on microstructuring of polymers enabling the creation of microprecision polymer masters. CPMT has a rich history in the broad field of micromoulding and has developed a custom mold installed on the same machine which allows the flexible integration of mold inserts inside the machine.

This combination allows the thesis cadidate to develop a complete micro injection process, which is the goal of this thesis. The different aspects of this complete process are as follows:

·         Design of testparts to be fabricated by micromoulding

·         Fabrication of polymer mold inserts containing the testpart shapes in the CMST cleanrooms

·         Integration of the mold inserts into the custom mold of CPMT in the Wittmann-Battenfeld machine

·         Testing of different methods and materials for increasing the precision of the moulded parts: compression molding, variotherm, IR-heating

·         Characterisation of the molded parts to provide feedback to the previous point

Locatie: Ardoyen (clean rooms) en thuis