GE Lexan.pdfOrganic Electronics (OE) AT Program at GRCUltra-high Barrier - GE’s ApproachSummaryECD Stainless Steel.pdfFlexible Stainless Steel Substrates for DisplaysBackgroundProblems with Plastic SubstratesAttractive Alternative -Stainless Steel SubstratesStainless Steel SubstratesComparison of SS & Flexible Other SubstratesTFT Circuits on SS Well ProvenFlexible Large-scale SS Substrates in Semiconductor ManufacturingRoll-to-Roll Ovonic PV Manufacturing LineProgram ScopeSpecific SS Substrate Issues - PlanarizationBare SS Smoothness ParametersPlanarization and Passivation LayersSchematic cross section (not to scale) of a passivated back-channel a-Si TFT and three substrates types: (a) glass, (b) plastPlanarization & Passivation Materials for Various Subsequent ProcessesPlanarized & Passivated SS Substrate Type APlanarized & Passivated SS Substrate Type BSS Substrate Sample SmoothnessSS Substrate Smoothness SummaryElectrical IsolationTFT CompatibilityCommercial Availability & EconomicsOutlook for Flexible SS SubstratesAcknowledgementsLatest Developments In Polyester Film For Flexible ElectronicsW MacDonald, K Rollins, D MacKerron, R Eveson, R Rustin, R Adam, K Looney, K Rakos and K Hashimoto- DuPont Teijin Films2Agenda• Factors influencing film choice– Introduction to DTF family of films for flexible displays• Characterisation of polyester films for flexible electronics– Surface quality– Mechanical properties of multilayer strucures– Control of dimensional reproducibility• Influence of planarising coating on barrier performance• Examples of DTF film in flex electronic application3Key Challenges for Engineered Substrates into Flexible Display applications• Low Coefficient of Thermal Expansion• Low Shrinkage• Upper Temperature for Processing• Surface smoothness• Barrier• Solvent Resistance• Moisture Resistance• Clarity• Rigidity• Conductive layers• Commercial availability• Substrates for the more demanding applications are likely to be multilayer structures containing both organic and inorganic layers4Factors Influencing Film Choice-Property Set“Simple” organic circuitryOrganic AM backplanesInorganic AM backplanesOLED displays Increasing complexity of substrate structureMore demanding property set5Factors Influencing Film Choice-Physical Form/Manufacturing Route• Physical form of display and type of usage will influence film choice particularly with respect to thickness– Flat but exploiting light weight, ruggedness– Conformable, one time fit to uneven surface– Flexible– Rollable• Batch, fast sheet and R2R processing– Rigidity6Rigidity• Rigidity (D) of Teonex of different thickness calculated below and compared relative to 25 micron film• Thickness has a significant effect on rigidityTeonex Thickness MicronsRigidity Nm x 10-4Rigidity relative to 25 micron film25 0.1 150 1 1075 3 30125 15 140175 40 390200 60 580D = E t312(1-ν)E is the tensile or Youngs Modulut is the thickness, ν is Poissons ratio (0.3-0.4).7Structure of PET and PEN FilmsBiaxially oriented, semicrystalline filmsTetoron®and Melinex®Polyethylene Terephthalate(PET)Teonex®Polyethylene Naphthalate(PEN)COOCH2CH2OCOnCCOOnPET Tm 255C Tg 78CPEN Tm 263C Tg 120 COCH2CH2OTetoron®and Melinex®Polyethylene Terephthalate(PET)Teonex®Polyethylene Naphthalate(PEN)COOCH2CH2OCOnCCOOnPET Tm 255C Tg 78CPEN Tm 263C Tg 120 COCH2CH2On8DTF Grades for Flexible Electronics• Teonex® Q65FA– One side pretreated, heat stabilised PEN film– “Thick” grade (>75 micron) with high clarity– Emerging as a leading material for OLED displays and AM backplanes• Teonex® Q83– “Thin” (25 and 50 micron), lightly filled,heat stabilised grade of PEN to give handleability• Melinex® ST506– 2 side pretreat, heat stabilised PET film– “Thick” grade• Melinex® ST504– 1 side pretreat, heat stabilised PET film– “Thick” grade9Key properties of Teonex® Q65FA compared with heat stabilised PET (eg Melinex® ST506)Glass transition, oCHaze %Moisture pickupat 20oC, 40%RHYoungs Modulusat 20oC, GPaYoungs Modulus at 150oC, GPaShrinkage in MD at 150oC after 30 mins (%)Upper temperature for processing, oC78oC120oC180-220oC18-20ppm/oC0.05%1000ppm0.7%150oC4GPa0.1%1000ppm0.7%5GPa3GPa20-25ppm/oC1GPaHeat stabilised PETTeonex® Q65ACTE ppm/oC10Surface Quality-Surface Smoothness• Micro roughness which is dictated by whether film is unfilled, filled, pretreat coated• Characterised by – AFM ▪ 1-50 micron field of view with lateral resolution down to nm’s– White Light Interferometry▪ Micron to cm field of view with lateral resolution down to ca 0.2 micron11Teonex FamilyTeonex®Q83Sample size 600x400umTeonex®Q65 “raw”Sample size 600x400micronTeonex®Q65 pretreatSample size 2x2 micron(NB AFM-different scale)50nm-25nm0nm12Surface Quality-Surface Smoothness• Within micro roughness possible to also see sporadic surface peaks up to 10’s microns lateral dimensions, 100’s nm height-illustrative examples below• Due to internal particulate burden both organic and inorganic• Largely controlled via polymer recipe, plant hygiene13Surface Quality- Surface Cleanliness• Surface Cleanliness, extent of which depends upon the 'external'contaminants such as air-borne debris, scratches, etc. Up to 10micron high, 10’s of microns long-illustrative examples shown below• Control through– surface cleaning eg tacky roller– planarising coating in clean roomDust-40 microns long10 microns highScratch 150 microns long0.5 microns high at ridge14Planarised Films• DTF is developing a family of planarising coatings that– Give glass smooth surfaces– Meet product requirements▪ hardness vs smoothness vs ability to withstand stress/strain▪ adhesion, solvent resistance, environmental resistance etc15Melinex ® ST506-Benefit of PlanarisationPretreat on Melinex ® ST506 gives good adhesion to subsequent coatingsBut at expense of surface roughnessRa 1.53nmSample size 594micronPlanarised Melinex ® ST506Very smooth surface-on a par withPolished glass mirrorRa 0.6nmSample size 608 microns16Effect of Planarising Coating on Reducing Surface PeaksExtreme Surface Peak 'Rp' (All high points > 25nm) - Frequency Distribution comparison, for Melinex ST504 non pre treated surface and hardcoat upon it's pre treated surface. 0100200300400500600700800900100040 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 < Rp height (nm)Rp