3M Ultra Transparent Electrically Conductive EMI/Shielding Film

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1 Technical Bulletin April, M Ultra Transparent Electrically Conductive EMI/Shielding Film General Description The 3M Ultra Transparent EMI (UTEMI) Electrically Conductive Shielding Films are a specialty coated polyester film with electrically conductive thin film coated on one surface. The 3M Transparent Electrically Conductive EMI Shielding Film optionally can be pre-laminated to a 3M Optically Clear Adhesive (OCA). The unique properties of transparent conductive coating allow high transmission in visible spectrum and provide EMI shield in radio and microwave frequency. Applications include EMI shield for touch screen, display screen (PDP, LCD and CRT) and windows. 3M Ultra Transparent Electrically Conductive/EMI Shielding Film 88xx Removable green cover Electrically conductive coating PET substrate 3M Ultra Transparent Electrically Conductive/EMI Shielding Film 88xx with OCA Removable green cover Electrically conductive coating PET substrate Optically clear adhesive Releasable liner Construction Property Coating Film Substrate Type Adhesive Type (optional) Approximate Thickness Removable Green Liner Format Construction Diagram Value 3M Electrically Conductive Coating (ECC) Polyester 3M Optically Clear Adhesive (2 mil) 2, 3 or 7 mil Yes-all thicknesses Roll only or Die Cut only See ULTEMI drawing 3

2 Selection of the 3M Ultra Transparent Electrically Conductive/EMI Shielding Film 88xx vs. an ITO on PET film for Transparency & Surface Resistance & EMI Shielding A PET film with single layer sputtered Indium Tin Oxide layer (ITO) for EMI shielding has two overlapping performance limitations: As Visual Transmittance increases, the EMI Shielding level is reduced as the ITO layer must be thinner. As EMI Shielding is increased with a thicker ITO film, the Visual Transmittance is reduced. Thus, for devices where improved EMI Shielding is desired, along with excellent Transmittance, the 3M Ultra Transparent Electrically Conductive/EMI Shielding Films 88xx are now available. The 3M Ultra Transparent Electrically Conductive/EMI Shielding Films 88xx offer a step-up in Transmittance with no loss in EMI Shielding. Thus, the designer can improve EMI Shielding and maintain Transmittance or improve Transmittance and maintain EMI shielding levels. 3M Ultra Transparent Electrically Conductive/EMI Shielding Film 88xx vs. PET ITO Technical Data Sheet (TDS) Values of Transmission % vs Surface Resistance* Transmission % based on TDS Values and Test Method Surface resistance is directly related to EMI Shielding: Lower R = Higher EMI Shielding Surface Resistance R (ohms/sq) based on TDS Values & Test Method Transmittance (%) PET-ITO Transmittance (%) 3M Ultra Transparent Electrically Conductive/EMI Shielding Film 88xx *Technical Data sheets value reviewed is for general reference only as the TDS values were derived using different test equipment & modified versions of ASTM D1003 and sample set-up. Note: Multi-layer ITO coated PET films may have a different Transparency vs Surface Resistance relationship than noted in the above data using a more complex manufacturing process. (2)

3 3M Ultra Transparent Electrically Conductive/EMI Shielding Film 88xx vs. an PET ITO or a Wire mesh EMI Film or Display The typical performance range of the UTEMI film, an ITO film and a Wire Mesh based EMI film are typically in the range of: PET ITO: 70-86% Transmission with Surface resistance of Ohms/square 3M Ultra Transparent Electrically Conductive/EMI Shielding Film 88xx: 83-91% Transmission with Surface resistance of Ohms/square Wire Mesh Based EMI Films/displays: 60-88% Transmission with Surface resistance of Ohms/square The Ohms/square relates to a potential EMI Shielding performance. Actual EMI Shielding is based on degree and effectiveness of grounding, but in general for a well grounded EMI solution one might expect: 0.1 to 1 ohms = db EMI Shielding range 1.0 to 10 ohms = db EMI Shielding range 10 to 30 ohms = db EMI Shielding range 30 to 150 ohms = 7-17 db EMI Shielding range 150 to 300 ohms = 4-7 db EMI Shielding range SE = 20 log (1+ ( Z / Rs )) : Rs = Surface Resistance Ohms/square, Z = Impedance of free space (377ohms/sq) The Typical Wire Mesh product has excellent EMI Shielding and Optical Transmission as compared to the PET ITO or UTEMI films, but requires a more costly and complex manufacturing process. Flexibility of the 3M Ultra Transparent Electrically Conductive/EMI Shielding Film 88xx vs. an ITO on PET Film The 3M Ultra Transparent Electrically Conductive/EMI Shielding Films 88xx has a more flexible conducting and dielectric layer vs. an ITO on PET film. ITO PET films Technical Data Sheets (TDS) typically express the need to use caution when handling or bending the films as they are easily damaged. The improved flexibility of the 3M films reduces potential for cracking and EMI leakage, lowers handling damage potential for increased yields and allows the 3M Ultra Transparent Electrically Conductive/EMI Shielding Film 88xx products to be used in applications where the film could experience a bending position or placement. Environmental Testing of 3M Ultra Transparent Electrically Conductive/EMI Shielding Film 88xx vs. an ITO PET Film The 3M Ultra Transparent Electrically Conductive/EMI Shielding Films 88xx and typical ITO PET films are evaluated for environmental resistance typically with a <100 Hours (ex: 65 C/90%RH for 72 hours exposure and evaluation). A common test is to evaluate the films for changes in Transmittance and/or Surface Resistance. (3)

4 Both the 3M Ultra Transparent Electrically Conductive/EMI Shielding Films 88xx and ITO PET films are designed to be used as a Second surface film, and not as the First or Primary surface exposed to direct environmental conditions. 3M Ultra Transparent Electrically Conductive/EMI Shielding Films 88xx are designed for use within enclosures and are not designed to be exposed to direct environmental conditions of an end use application. 3M Ultra Transparent Electrically Conductive/EMI Shielding Films 88xx environmental performance is influenced by the final assembly design construction. Each end user needs to determine fitness for use of the UTEMI film in their intended end use assembly and anticipated environmental conditions as this will affect the UTEMI film performance. 3M Ultra Transparent Electrically Conductive/EMI Shielding Film 88xx Sample Preparation for Testing: 3M Ultra Transparent Electrically Conductive EMI Shielding Film was laminated to a glass slide (Erie Scientific 2957F) using 3M Optically Clear Adhesive (OCA) unless noted otherwise. Optical measurements were made using a BYK Gardner TCS Plus Spectrophotometer model 8870 (BYK Gardner, USA) in accordance with ASTM D1003, E308, CIE Spectral response measures visible spectrum from 380 to 720 nm using d/8º geometry where total reflectance is specular included. Handling. 3M Ultra Transparent Electrically Conductive/EMI Shielding Films are provided with a removable protective cover liner to protect from typical handling damage. The protective film layer protecting the conductive film layer should be removed in the final stage of the assembly process. Care should be taken when handling the transparent conductive film to avoid contamination, scratches or degradation to the coated surface. Using gloves helps to prevent transfer of finger print oil to conductive coating or non-conductive coating side is suggested. Moving the conductive coating over a surface may result in scratching the coating, visual defects and lower reliability. It is suggested that if cleaning is needed of the 3M Ultra Transparent Electrically Conductive/EMI Shielding Film 88xx, a 90%/10% IPA/Water blend be used. Blot only with a non-scratch cloth to prevent damage to the conductive surface. The 3M Ultra Transparent Electrically Conductive/EMI Shielding Film 88xx is flexible, but care should be taken to minimize any mechanical damage to the conductive surface on the film when handling. (4)

5 Grounding of the 3M Ultra Transparent Electrically Conductive/EMI Shielding Film 88xx The 3M Ultra Transparent Electrically Conductive/EMI Shielding Films 88xx can be grounded to improve or enhance the EMI Shielding performance of the film. Care should be taken in selection of a grounding tape to ensure surface compatibility. In general, the 3M Ultra Transparent Electrically Conductive/EMI Shielding Films 88xx can be tested for effective grounding with a selection of 3M Electrically Conductive Adhesive Transfer Tapes. Suggested ECATT tapes to be considered and evaluated include, but is not limited to, 3M ECATT 9709S, 9725 and Final assembly configuration, environmental conditions, end use conditions, etc. will impact the final ECATT grounding performance and should be evaluated to determine fitness for use. EMI Shielding and Electrical Connection. 3M Ultra Transparent Electrically Conductive / EMI Shielding Films (UTEMIF) can be integrated into display assemblies with varying degree s of EMI Shielding performance. A design that grounds UTEMIF as part of a Faraday enclosure configuration offers the optimum performance of the UTEMIF film. The shielding function of the conductive film may not be fully utilized if the UTEMIF is not grounded. Each end use application needs to test and validate if the 3M Ultra Transparent Electrically Conductive/EMI Shielding Film 88xx needs to be grounded to meet the end users performance needs. In some applications, the UTEMI shielding film may act as an antenna if the desired Faraday cage design is not properly completed or terminated (for example, touch screen with transparent EMI shielding film applied to the back is terminated on one corner). The EMI attenuation level depends on surface resistance of the conductive film, lower resistance correlates to higher EMI shielding. Good electrical contact with conductive film is essential for grounding and EMI shielding requirements. Unlike a metal foil, the 3M Ultra Transparent Electrically Conductive/EMI Shielding Films 88xx transparent conductive coating is very thin (< micron thick), direct physical contact with sharp probes such as alligator clips may poke through the coating and result in poorly reliable contact. Electrically Conductive Adhesive Transfer Tapes (ECATT) or gaskets which are compatible with the UTEMI film s conductive coating can also be used for electrical connection. Anti-Reflection (AR) Properties: The 3M Ultra Transparent Electrically Conductive/EMI Shielding Films 88xx may be designed with surface optical properties to minimize surface reflection over the entire visible spectrum and is optimized when the conductive film surface side is exposed to an air interface. The AR coating provides for low reflection to the air interface to enhance the display contrast and enhances transmission. Since the AR coating is optimized for air as the incident medium, it is not recommended to apply adhesive or coating on the conductive coating side of the film as this will affect the AR performance. Depending on end-user design, doing so may or may not reduce the optical performance of the stack or laminate of the end use design. (5)

6 OCA Adhesive Lamination. 3M Optically Clear Adhesive (OCA) or 3M(tm) Contrast Enhancement Film (CEF) is recommended for product lamination. For lamination of Transparent EMI Film with OCA / Or applications of Transparent EMI Film with pre-applied OCA, the 3M OCA Lamination document should be review: The lamination of an OCA adhesive film to the UTEMI non-conductive side is suggested. The lamination process overview is found below: For detailed information, please request the complete document. 3M Optically Clear Adhesive and 3M Contrast Enhancement Film Step by Step Bubble-Free Lamination and Product Recommendation General Description This bulletin describes the method of laminating rigid-to-flex or rigid-to-rigid surfaces using 3M Optically Clear Adhesive (OCA) or 3M Contrast Enhancement Film (CEF) for prototype purposes. The information presented in this bulletin should be considered representative or typical. The user is responsible for evaluating the lamination process under actual conditions of use and with the substrates intended for the customer application to determine specific process parameters necessary in the individual customer s application. Process Overview High quality rigid-to-rigid and rigid-to-flexible lamination requires special lamination equipment. Hand lamination is to be used only for proving concepts. The lamination process is described in detail in the next section. Substrates first need to be laminated together and inspected for entrapped air. If signs of air entrapment are observed, the laminate needs to be autoclaved to remove air. When one of the substrates is polycarbonate (PC) or Acrylic (PMMA), extra testing is required to ensure the plastic is not outgassing. Substrates such as PC and PMMA tend to absorb moisture and outgas when exposed to high temperature and high humidity, creating bubble defects in laminated parts. Plastics can be prebaked to drive moisture out. Process Description A brief description of lamination process is provided in the following table. Brief Summary of Lamination Process Pre-bake in dry, clean oven Temperature 85 C (for PMMA and PC only) Duration 2-5 hours Lamination Room Clean Room Temperature Room 24 C and above Autoclave Temperature C Pressure Duration PSI minutes Durability Temperature 60 C Humidity Duration 90% R.H hours A comprehensive description of lamination process is provided in the following section. (6)

7 Review of Basic Properties of the3m Ultra Transparent Electrically Conductive/EMI Shielding Film 88xx Properties as noted in TDS Consult Technical Data Page for property values ranges. Haze: A reduction in transparency related to the PET film (type, thickness) and ECC properties. Haze data in the technical data pages were under A or C illuminants for 2º observers. Transmitted & Reflected Color (CIE Yxy): When light strikes an interface between two materials (Air/PET, PET/PET, Air/Glass/OCA/PET, etc.), the change in refractive index at the interface(s) can cause light to be reflected at the interface surface or refracted into the material at the interface. Light entering the next material can be: Absorbed, Transmitted through the material, or Scattered within the interface and it may eventually pass out of the front, back or side of the material. In optical grade PET s, the majority of the light that enters the film is transmitted through the film. As visual light is in a frequency range from generally nm,and the human eye perceives the frequencies in the brain as a color. We have come to associate a subset of these frequencies ranges with a set of Primary colors with a Blue (Z) 450nm, Green (Y) 550nm and a Red 600nm. Thus, any color of the spectrum can be obtained by varying the XYZ content and where they are on the relative scale for the primary color (ie: Blue Z generally ranges from 380nm to about 540nm). As a test means to review the Transparent EMI films characteristics, colorimetric data was collected in CIE Yxy (1931) and CIE LABL*a*b* (1976) color scales under D65 illuminants for 10º observers. The CIE is the French abbreviation for the Commision International de l Eclairage (ie: International Commission on Light). The CIE in 1931 devised a test method of using the 3 primary colors in an additive mixture to describe any color mixture: The revised CIE LAB (L*a*b*) (1976) was devised to relate an intensity of the 3 primary colors of Red, Green and Blue. Lightness (L*), Redness/Greenness (a*) and Yellowness/Blueness (b*).the a* and b* are mathematically related to the Yxy colors based on test method specifics. For CIE LAB (L*a*b*), the L* relates to Total Luminance Transmission through the film (other light is absorbed or reflected) or Lightness with the scale being from 0 (black) to 100-(white), a* and b* scales vary by the specific test set-up, but range from - to + values. Total Luminous Transmittance & Reflectance: Percentage total luminous reflectance and percentage luminous transmittance were taken as value of chromaticity Y. Luminous reflectance was measured with a blackened glass slide (glass side of the laminate, opposite to conductive coating side, was spray-painted with Rust Oleum black epoxy model ). For 3M TEMI Films with OCA and laminated to glass without black coating on glass backside, typical luminous reflectance was measured at a higher % due to glass backside reflection. For 3M TEMI Film that are Free Standing film (without black coating on PET backside), luminous transmittance and reflectance will vary with test method and exact sample configuration. Wave length frequency range is nm for transmittance. Reflectance wave length 550nm. (7)

8 Infared Transmittance: 3M Ultra Transparent Electrically Conductive/EMI Shielding Films 88xx are typically < 5-10% in the IR frequency range (> 800nm) for transmittance. Surface Resistance: Surface resistance was measured by a non-contact Eddy current method using Delcom Bench top Conductance Monitor model 717B (Delcom Instruments, Inc., USA). EMI Shielding Effectiveness: Shielding effectiveness (SE) for frequency range of 100 MHz - 3 GHz was characterized using ASTM D4935 (TEM cell method), for higher frequency range, a modified IEEE 299 test procedure for SE for enclosure (antenna-to-antenna method) was utilized. Electrical Breakdown Strength: Electrical breakdown strength was estimated using ASTM D149. Durability: Thermal durability of heat & humidity resistance of the 3M Transparent Electrically Conductive EMI Shielding Film test was determined by examining the changes in surface resistance ( R/R0 x.x%), changes in transmittance ( T/T0 x.x%) and appearance of visual defects after exposure to environmental aging conditions Visual Spectra Region: The frequency range of the Electro Magnetic Spectrum association with what the human eye can perceive. The frequency range is typically noted as 380nm to 780nm. This spectral range is of most interest when reviewing light Transmission % and color information regarding Transparent EMI films. (8)

9 Certification/Recognition MSDS: 3M has not prepared a MSDS for this product which is not subject to the MSDS requirements of the Occupational Safety and Health Administration s Hazard Communication Standard, 29 C.F.R (b)(6)(v). When used under reasonable conditions or in accordance with the 3M directions for use, the product should not present a health and safety hazard. However, use or processing of the product in a manner not in accordance with the directions for use may affect its performance and present potential health and safety hazards. TSCA: This product is defined as an article under the Toxic Substances Control Act and therefore, it is exempt from inventory listing requirements. RoHs Complaint/REACH Compliant: This product complies with the European Union s Restriction of Hazardous Substances (RoHs) initiative and with European REACH regulations 2002/95/EC and 2005/618/EC. For Additional Information To request additional product information or to arrange for sales assistance, call toll free Address correspondence to: 3M, Electronics Markets Materials Division, 3M Center, Building 225-3S-06, St. Paul, MN Our fax number is or In Canada, phone: In Puerto Rico, phone: In Mexico, phone: Important Notice All statements, technical information, and recommendations related to 3M s products are based on information believed to be reliable, but the accuracy or completeness is not guaranteed. Before using this product, you must evaluate it and determine if it is suitable for your intended application. You assume all risks and liability associated with such use. Any statements related to the product which are not contained in 3M s current publications, or any contrary statements contained on your purchase order shall have no force or effect unless expressly agreed upon, in writing, by an authorized officer of 3M. Warranty; Limited Remedy; Limited Liability. This product will be free from defects in material and manufacture at the time of purchase. 3M MAKES NO OTHER WARRANTIES INCLUDING, BUT NOT LIMITED TO, ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. If this product is defective within the warranty period stated above, your exclusive remedy shall be, at 3M s option, to replace or repair the 3M product or refund the purchase price of the 3M product. Except where prohibited by law, 3M will not be liable for any indirect, special, incidental or consequential loss or damage arising from this 3M product, regardless of the legal theory asserted. 3 Electronics Markets Materials Division 3M Center, Building 225-3S-06 St. Paul, MN phone fax 3M is a trademark of 3M Company. Please recycle. Printed in U.S.A. 3M All rights reserved (9) 3

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