Microlens Fabrication by the Modified LIGA Process and Hot Embossing Process

Abstract

Microlens and microlens arrays is realized using a novel fabrication technology based on the exposure of a resist, usually PMMA, to deep X-rays and subsequent thermal treatment. The fabrication technology is very simple and produces microlenses and microlens arrays with good surface roughness (less than 1 nm). The molecular weight and glass transition temperature of PMMA is reduced when it is irradiated with deep X-rays. The microlenses were produced through the effects of volume change, surface tension, and reflow during thermal treatment of irradiated PMMA. Microlenses were produced with diameters ranging from 30 to 1500 μm. Moreover, fabrication of the microlens through the hot embossing process is studied based upon a microlens mold insert fabricated by the modified LIGA process. A hot embossing machine is designed and manufactured. The hot embossing process follows steps of heating a mold to desired temperature, embossing a mold insert on substrate, cooling the mold to deembossing temperature, and deembossing.

Review on micro molding of thermoplastic polymers

“…Another wide spread article are holograms which are affixed to credit cards [26]. Other molded micro optical components are spectrometers [35,62] (see Figure 11(a)), lenses [65][66][67], optical switches [68,69], optical fiber connectors [2], waveguides [27,70,71], anti-reflective surfaces [72], optical gratings [9,25], and photonic structures [73].…”

A femtosecond laser-induced two-photon photopolymerization technique for structuring microlenses

“…In most of these cases, fabrication technology continues to be the prerequisite for the success of these developments. As a result many techniques for formation of refractive microlens arrays have been developed over past decades [9], such as photoresist reflow [10], the LIGA process [11], e-beam writing [12], pulsed laser ablation [13], focused ion beam technology [14], MeV proton deep lithography [15] and others. Each of these fabrication methods has its own advantages and disadvantages, mainly with respect to the physical type and quality of the microlenses and fabrication time.…”

Investigation of Geometrical Defect of AA6061-T4 Cold Embossing Using FEM

“…fold, shear defect, surface defect, form defect, crack and structural defect. There are many causes of defect including die deflection [4], yielding or wear [5] and eccentricity or buckling due to the flow imperfection [6]. Recently, metal flow imperfection related defect has devoted attention by many researchers [7][8].…”