Thermal nanoimprinting lithography hot embossing

Transcription

1 Thermal nanoimprinting lithography hot embossing Painettavan elektroniikan jatkokurssi Dr. Jukka Hast Principal Scientist, Team leader, Adjunct Professor VTT Technical Research Centre of Finland

2 2 HOT EMBOSSING - GENERAL Principle of Hot Embossing Mechanical structures are embossed on to thermoplastic web under pressure and heat; close or above material s glass transition temperature (T g ) Embossing mold electroformed Ni-shims, laser or e-beam originated Features sizes Horizontal: nanometers to millimeters Vertical: tens of nm:s to tens of µm:s Plastic web Hot-embossing roll Heat Heat Pressure roll Embossing roll Pressure roll

3 3 Materials for Hot Embossing Thermoplastic polymers are used. Other materials can be coated with some thermoplastic material. Suitable thermoplastic materials: Acrylics like poly methyl metacrylate (PMMA), poly methyl butacrylate (PAM) and their blends Polystyrene (PS), Polycarbonate (PC), Cyclic Olefin Copolymer (COC) and Cylic Olefin Polymer (COP), amorphous polyethylene terephtalate (apet), cellulose aceteate (CA), polyethylene (PE), polypropylene (PP) Non thermoplastic materials that have to be coated first with thermoplastic coating, like lacquer: Cartons, papers and fibreboards, Semicrystalline polymers like oriented PET, polyethylene naphtalate (PEN), Polyimidie (PI)

4 4 Materials for Hot Embossing - Lots of information gathered to different websites, such as some common thermoplastics and their glass transition temperatures mentioned below Polymer Glass transition temperature (T g ) [ C] Example of trade names Polycarbonate (PC) Lexan, Makrofol, Cellulose acetate (CA) Clarifoil Cyclic olefin polymers COC / COP Polymethylmetacrylate (PMMA) (acrylic films more general), Amorphous Polyethylene terephtalate (apet) Topas, Zeonor Plexiglass 63 Hostapet, Villpet, Polylactide (PLA) Terramac, Polystyrene (PS) C Polyflex,

5 5 PRINCIPLE OF HOT EMBOSSING PROCESS Nickel shim (mold) Cellulose Acetate (CA) film AFM- picture, sine shaped metal shim: period of 1,05 m Replique of the shim on cellulose acetate film

6 6 PRINCIPLE OF HOT EMBOSSING PROCESS - DEFECTS Wrong parameters or materials may cause lots of different defects Uncomplete filling (for example too low temperature) Shim / mold Shim / mold Shim / mold substrate Perfect filling of binary structure substrate Incomplete filling / bad demolding of binary structure substrate Incomplete filling of binary structure

7 7 PRINCIPLE OF HOT EMBOSSING PROCESS - DEFECTS Rough surface can be a consequence of poor mold, wrong process parameters or rough starting material, therefore also coating step is important Binary shaped grating. Acrylic coating on PET film Smooth surface Binary shaped grating Acrylic coating on PET film Poor surface

8 8 HOT EMBOSSING EQUIPMENTS Flat-bed embosser testing of designs optimization preliminary tests low volume production Roll to roll printing machine with hotembossing unit pilot production final production in high volumes coating or printing on same substrate

9 9 R2R hot embossing R2R hot embossing of diffractive optical elements.

10 10 Components Produced by Hot Embossing Decorative effects on papers or on plastics for brand promotion Example by Nanocomp Microfluidic channels in polymer films for diagonstic applications Hidden pictures made visible by laser illumination for brand protection (covert)

11 11 DIFFRACTION coherent beam Incident (white) light reflected (white) light diffracted beams of 1st, 2nd and 3rd order diffracted spectrum 3rd 2nd 1st 1st 2nd 3rd surface with embossed grating surface with embossed grating d(sin m +sin i )=m d = grating constant i = angle of incident m = integer = wavelength

12 12 R2R HOT EMBOSSED OPTICAL GRATINGS Nano-structured diffractive gratings Light coupling in/out material Dynamic colors and effects on plastic, paper or board

13 13 R2R HOT EMBOSSED KINEGRAMS informative and / or decorative effects on product packages Security features, anticounterfeiting JoY

14 14 PROTECTION OF THE GRATING Grating is easily contamined by fingerprints etc. (by the end user) which kills the optical effect need to protect the effect Protection is essential in consumer goods as well as in laminated structures Solution: coating the effect with layer of higher refractive index Conventional method: vacuum evaporation of ZnS or Al Wet deposition in same printing line with embossing unit is also possible in line coating

15 15 R2R HOT EMBOSSED FRESNEL MIRROR informative and/or decorative effects on product packages taskulamppu Incoherent light Inkoherentti valolähde source Fresnelpeilimatriisi mirror matrix Image from Fresnel mirror matrix Fresnel-peilimatriisin tuottama kuva

16 16 R2R HOT EMBOSSED OROM ELEMENT R2R hot embossed reflective type diffractive optical element Size 2*2 mm May contain several A4 pages of information (~250 kb/cm 2 ) Illumination with laser Create 2D bar-code Reading with mobile terminal Add-on optics for mobile phone developed at VTT T. Haring

17 17 R2R HOT EMBOSSED MICROFLUIDICS Lab-on-a-chip: sample delivery sample mixing sample filtering Capillary electrophoresis on disposable plastic chips TRAC-on-Chip analysis of six selected mrnas from totrna (5 µg) extracted from VCap cells. fluorescence unit time (s) Microfluidic mixer

18 18 ACTIVE ELECTRICAL COMPONENTS Transistor is extremely important component for printed electronics Key component when developing advanced printed electrical applications Traditional printing techniques have printing resolution in tens of µms => large channel lengths Hot embossing (imprinting) is promising tool for < 1 µm channel lengths Imprint pattern in the etch resist that is printed on the gate electrode

19 19 SUMMARY R2R hot embossing is useful tool in different applications of printed electronics and optics High volume mass production good repeatability Commercial product examples Microfluidics Decorative diffractive components Anti-counterfeit products Promises and interests for future are high OTFT patterning Point of Care diagnostics

20 20 VTT creates business from technology