TEST METHOD FOR PARTICLE REMOVAL PERFORMANCE OF LIQUID FILTER RATED BELOW

Transcription

1 Background Statement for SEMI Draft Document 5421A New Standard: TEST METHOD FOR PARTICLE REMOVAL PERFORMANCE OF LIQUID FILTER RATED BELOW 30 nm WITH ICP- MS Notice: This background statement is not part of the balloted item. It is provided solely to assist the recipient in reaching an informed decision based on the rationale of the activity that preceded the creation of this Document. Notice: Recipients of this Document are invited to submit, with their comments, notification of any relevant patented technology or copyrighted items of which they are aware and to provide supporting documentation. In this context, patented technology is defined as technology for which a patent has issued or has been applied for. In the latter case, only publicly available information on the contents of the patent application is to be provided. Background Statement This document is an extension of Doc (published as SEMI C82) which describes the test method for particle removal performance of liquid filter rated nm with optical particle counter. The test particle as tracer material is gold nanoparticle (GNP) certified as National Institute of Science and Technology (NIST) -Reference Material, as similarly used at SEMI C82 standard. This document describes the test method for below 30 nm-rated filter mainly used for chemical filtration by using GNP and ICP-MS as particle concentration detector. If you have any questions on this ballot, please contact the following Task Force leaders or SEMI Staff: Liquid Filter Task Force co-leaders: Takuya Nagafuchi (Nihon Entegris) at takuya_nagafuchi@entegris.com Takehito Mizuno (Nihon Pall) at takehito_mizuno@ap.pall.com SEMI Staff : Chie Yanagisawa (SEMI Japan) at cyanagisawa@semi.org The ballot results will be reviewed and adjudicated at the meetings indicated in the table below. Check under Calendar of Events for the latest update. Review and Adjudication Information Task Force Review Committee Adjudication Group: Liquid Filter TF Japan Liquid Chemicals Committee Date: Friday, Apr 11, 2014 Friday, Apr 11, 2014 Time & Timezone: 14:00-15:00, Japan Time 15:00-17:00, Japan Time Location: SEMI Japan Office SEMI Japan Office City, State/Country: Tokyo, Japan Tokyo, Japan Leader(s): Takuya Nagafuchi (Nihon Entegris) Takehito Mizuno (Nihon Pall) Hiroshi Tomita (Toshiba) Hiroyuki Araki (Dainippon Screen Mfg.) Standards Staff: Chie Yanagisawa (SEMI Japan) / cyanagisawa@semi.org Chie Yanagisawa (SEMI Japan) / cyanagisawa@semi.org

2 The task force review meeting s details are subject to change, and additional review sessions may be scheduled if necessary. Contact Standards staff for confirmation. Telephone and web information will be distributed to interested parties as the meeting date approaches. If you will not be able to attend these meetings in person but would like to participate by telephone/web, please contact Standards staff. If you need a copy of the documents in order to cast a vote, please contact the following person within SEMI. Chie Yanagisawa SEMI Standards, SEMI Japan Tel: cyanagisawa@semi.org

3 SEMI Draft Document 5421A New Standard: TEST METHOD FOR PARTICLE REMOVAL PERFORMANCE OF LIQUID FILTER RATED BELOW 30 nm WITH ICP- MS 1 Purpose 1.1 This document is to provide a standard of mono-dispersed gold nanoparticle (GNP) challenge test for liquid filter rated below 30 nm using ICP-MS. 2 Scope 2.1 This document covers a mono-dispersed GNP challenge test method for below 30 nm rated liquid filter. 2.2 This document defines a test condition for mono-dispersed GNP challenge test. 2.3 The following areas are to be addressed in this document: The test condition such as fluid, flow rate, pressure, GNP concentration, ligand concentration, membrane treatment etc. The type of filter evaluated. The type of gold nanoparticle (GNP) The method of membrane treatment prior to the test for decreasing the adsorbing effect. The description of the test result. NOTICE: SEMI Standards and Safety Guidelines do not purport to address all safety issues associated with their use. It is the responsibility of the users of the Documents to establish appropriate safety and health practices, and determine the applicability of regulatory or other limitations prior to use. 3 Limitations 3.1 The test procedure is destructive; the filter cannot be returned into operation. 3.2 Fresh filter shall be used for this test procedure. 3.3 Material purity and potential leaching of dissolved contaminants are not addressed by this standard. SEMI F57 does not address this issue for final filters therefore the end user may decide to consider such testing when selecting different types of filters. 3.4 Test parameters affect the outcome of the test described in this standard, therefore test results are a qualitative rather than a quantitative of filter performance. This standard recommends testing filters under the conditions optimized in this standard and describe the conditions in test report. 3.5 Test shall be conducted as side by side comparison using more than one filter. Accordingly, the variability of the challenged particle in size is allowed in this test. 4 Referenced Standards and Documents 4.1 SEMI Standards and Safety Guidelines SEMI F110 Test Method for Mono-dispersed Polystyrene Latex (PSL) Challenge of Liquid Filters SEMI C79 Guide to Evaluate the Efficacy of Sub-15 nm Filters Used in Ultrapure Water (UPW) Distributions Systems SEMI C82 Test Method for Particle Removal Performance of Liquid Filter Rated nm with Liquid-Borne Particle Counter. NOTICE: Unless otherwise indicated, all documents cited shall be the latest published versions. Page 3 Doc. 5421A SEMI

4 5 Terminology 5.1 Abbreviations and Acronyms APD 2-amino-2-hydroxymethyl-1,3-propanediol DLS dynamic light scattering FM flow meter GNP gold nanoparticle ICP-MS inductively coupled plasma mass spectroscopy LPM liter per minute (L/min) LRV log reduction value MSA Mercaptosuccinic acid NIST National Institute of Standards and Technology OPC optical particle counter P pressure gauge PSL polystyrene latex SAXS small angle X-ray scattering T thermometer UPW ultrapure water 5.2 Definitions background the gold concentration when feeding the water without GNP challenge the feed the water including GNP and ligand to test filter efficiency particle removal efficiency of filter measured by this test method. It is the effectiveness of the filter in removing the particles, and is measured as (Upstream Downstream)/Upstream ligand ion or molecule (chemicals) that could bind with the surface of gold nanoparticle log reduction value (LRV) log reduction value of filter measured by test method. This is measured as logarithmic value of ratio of upstream to downstream particle counts. 6 Summary of Test Method 6.1 This test method describes that test equipment and procedures for determining the particle removal efficiency of liquid filter (below 30 nm) with the water including ligand and GNP by calculating the difference of the number of challenged particle between upstream and downstream. The concentration of challenged GNP is measured with ICP- MS. 7 Apparatus 7.1 Test Device For this test method, use the schematic shown in Figure The standard test device shall consist of a pre-filter, flow meters, a particle and ligand injection device, static mixer, pressure gauges, a test filter, a particle counter, flow control valves, a resistivity sensor, a thermometer, and tubing connecting them The pore size of a pre-filter shall be equal to or smaller than the pore size of a test filter Use a flow meter with an allowable error to less than 5% full scale and of appropriate range Use a pressure gauge with an allowable error to less than 1% full scale and of appropriate range. Page 4 Doc. 5421A SEMI

5 7.1.6 Use a thermometer with an allowable error to less than 1% full scale and of appropriate range Use a tubing with an inner diameter that does not lead to significant pressure loss for the fluid medium used in the test. UPW FM Ligand 7.2 Particle Injection Device Prefilter GNP Static Mixer Figure 1 Schematic of Typical Test Setup (Example) Test filter T1 P1 P Use a particle injection device that can inject a particle at a constant flow rate without a pulsation. 7.3 Ligand Injection Device Use a ligand injection device that can inject a ligand at a constant flow rate without a pulsation. 7.4 ICP-MS Use an ICP-MS capable of detecting more than 0.1 ppb quantitative limit of gold Sample solution containing GNP shall be dissolved with aqua regia prior to injecting into ICP-MS. 8 Reagents and Materials 8.1 Ultrapure Water (UPW) Use the supply UPW with the resistivity more than 17MΩ cm Temperature of the UPW shall be adjusted to 25±5. NOTE 1: As some ligands or other surfactants are added to actual challenge solution, there is no need to adhere to the resistivity described in at challenge test. 8.2 Gold nanoparticle (GNP) Use the mono-dispersed GNP certified by NIST or the mono-dispersed NIST-traceable GNP The mono-dispersed GNP with below 30 nm of particle size is used. NOTE 2: In Appendix 2, the average particle size of NIST reference materials (RM) is described 8.3 Ligand Use a ligand to make colloidal GNP stably disperse and decrease the interaction between GNP and filter media. (please see the Appendix 1) 9 Test Specimens 9.1 Use a virgin liquid filter from rating below 30 nm. 9.2 Any size and type of filter, such as disk, capsule or cartridge, can be used in the test. Page 5 Doc. 5421A SEMI

6 10 Procedure 10.1 General Procedures The filter is evaluated by the following procedures: Testline background Filter pretreatment and filter flushing Background Challenge 10.2 Testline background Background testing is required for every test before installing the test filter into the test line (see Figure 1 or Figure 2) Set the test condition (flow rate and pressure) UPW (Resistivity: 17MΩ cm, temperature: 25±5 ) FM Choose either standard below: 1. Filter size standard: n L/min at 25.4*n mm-sized (n inch-sized) filter, (n=1,2,3,4,5.) 2. Filter media surface area standard: the flow rate to achieve the flux of >0.1 ml/min/cm 2. P2: 100 kpa NOTE 3: A downstream pressure of at least 100 kpa has to be maintained in order to eliminate air in the system Collect the test line water and measure gold concentration with ICP-MS Confirm the concentration becomes below detection limit, and record Filter Pretreatment Pre-wetting is needed if the test filter is hydrophobic (Follow filter manufacturer's instructions) Pretreatment fluid is aqueous solution of a ligand used at the challenge test. The concentration shall be same with the concentration at the challenge test. NOTE 4: The condition of ligand concentration to achieve the lowest adsorbing effect depends on membrane type. Accordingly, it is necessary to optimize it in advance. Please see Appendix 1 in terms of how to set the ligand condition Fill the membrane pore with the pretreatment fluid by flowing after installing into the test line After , soak filters in the pretreatment fluid for a minimum of 30 min Background Start UPW flow and ligand injection Close the air-vent valve after venting air from the filter upstream Set the test condition (flow rate and pressure). UPW (Resistivity: 17MΩ cm, temperature: 25±5 ) FM Choose either standard below: 1. Filter size standard: n L/min at 25.4*n mm-sized (n inch-sized) filter, (n=1,2,3,4,5.) 2. Filter media surface area standard: the flow rate to achieve the flux of >0.1 ml/min/cm 2. P2: 100 kpa Page 6 Doc. 5421A SEMI

7 NOTE 5: A downstream pressure of at least 100 kpa has to be maintained in order to eliminate air in the system Collect the downstream of the filter and measure gold concentration with ICP-MS Record the concentration. NOTE 6: If the gold concentration does not become below detection limit, terminate the challenge test and re-check test line and other apparatuses. Then, restart the challenge test from Challenge Prepare the challenge mono-dispersed GNP. When the challenge solution is diluted, it is necessary to use UPW characterized at 8.1 and agitate sufficiently. The prepared challenge solution shall be used in the test within 24h. Preferably, the particle size in the solution also should be evaluated with the instrument such as DLS, and SAXS in case the particle aggregation might occur. The purpose of this measurement is to confirm that no existence of large aggregated particle in the challenge solution. Large particles may affect removal efficiency of the tested filter, which may cause overestimate the removal capability of the filter. If obviously larger particles than estimated challenge particle size are observed, the challenge test shall be terminated Set the test condition (flow rate and pressure). FM Choose either standard below: 1. Filter size standard: n L/min at 25.4*n mm-sized (n inch-sized) filter, (n=1,2,3,4,5.) 2. Filter media surface area standard: the flow rate to achieve the flux of >0.1 ml/min/cm 2. P2: 100kPa NOTE 7: A downstream pressure of at least 100 kpa has to be maintained in order to eliminate air in the system Turn on the injection pump which delivers the challenge solution prepared at Begin injection at rate to achieve <100 ppb (calculated actual number diluted from the original GNP concentration). NOTE 8: The challenge level shall be defined in terms of the concentration at the filter after diluting in the main flow. Record downstream pressure reading Run test for achieving below the order of pcs/cm 2 of the number of total challenged particle by tuning challenged GNP concentration and time. Table 1 summarizes examples of the testing condition. Table 1 Examples of the test condition in terms of concentration filter surface area, and challenging time. GNP size (nm) GNP concentration (ppb) GNP particles (pcs/ml) Flow rate (L/min) Filter Surface area (cm 2 ) Time (min) Accumulated challenge level (pcs/cm 2 ) Membrane coverage area (cm 2 ) E , E E , E Membrane Coverage rate (%) Record particle levels in upstream and downstream each Monitor particle levels downstream of the filter Turn off injection pump Turn flow off at inlet valve Open drain and vent valves Remove test filter. Page 7 Doc. 5421A SEMI

8 11 Calculations 11.1 Particle removal efficiency (%) and LRV are calculated using the average of the data points from last half for downstream levels and the measured upstream value. 12 Report % Efficiency = (Upstream Downstream)/Upstream 100% (1) LRV = Log(Upstream/Downstream) (2) 12.1 Include the system setup, which includes the particle data system settings Include calculated efficiencies and LRV, shown in Table 1 (sample data) Report resistivity, temperature and flux. Table 2 Sample Data Format (Example) Filter / Filter size/ Lot number A Average GNP size (nm) and Coefficient variation (-) 30, < 20% GNP manufacturer/ Lot number A GNP concentration (N/ml) 1E+8 Water resistivity (MΩ) 18.2 Water temperature ( ) 23 Challenging time (min) 60 Ligand / Ligand concentration (mmol/l) MSA / 0.3 Main flow rate (L/min) 10 Side flow rate (L/min) 0.1 Flux (ml/min/cm 2 ) 0.5 ICP-MS manufacturer/ Model number A Background Average (ppb) < DL Upstream Average (ppb) 50 Downstream Average (ppb) 0.05 Efficiency (%) 99.9 LRV (-) 3 #1 Downstream values were calculated by averaging last half data recorded. Page 8 Doc. 5421A SEMI

9 APPENDIX 1 Ligand addition NOTICE: The material in this Appendix is an official part of SEMI [designation number] and was approved by full letter ballot procedures on [A&R approval date]. A1-1 Purpose of ligand addition A1-1.1 As the GNP used in this standard has very small size, some disturbance such as concentration change, contamination of foreign object, and ph change could easily cause aggregation or sedimentation of GNP. Also, the interaction between GNP and filter media is extremely high and GNP could be adsorbed on the surface of filter media. A1-1.2 In order to stabilize GNP colloidal system and prevent filter media from adsorbing GNP, it is preferable to use ligand technique. Precious metal like gold and platinum can bind with sulfur element and the molecule including amino group with a coordination bond 1) 2). Thus, the gold surface could be easily modified by molecules including thiol or amino functional groups. A1-2 Polyethylene filter A1-2.1 For polyethylene filter, a branched or bulky ligand like Mercaptosuccinic acid (MSA) including carboxyl group could reduce adsorbing effect 3). Figure A1-1 shows the schematic drawing of atomic configuration of MSA molecule combing with GNP. GNP is entirely covered with MSA ligand by adding the ligand into GNP challenge solution, and the GNP covered with MSA is difficult to approach to filter media surface by steric effect. Furthermore, when the GNP challenge solution including MSA is injected into main line, it is expected that the colloidal system might be instable because MSA concentration is rapidly decreased. Therefore, previously adding MSA ligand into main line at upstream of GNP injection line. A1-2.2 Also, p-mercaptobenzoic acid can be used as acting similar with MSA 3). Table A1-1 summarizes the representative ligands which have an ability to reduce adsorptive interaction between GNP and PE membrane. Figure A1-1 Schematic drawing of atomic configuration of MSA molecule combining with GNP. Sulfur element is combined with gold element. Page 9 Doc. 5421A SEMI

10 Table A1-1 Representative ligands to have an ability to reduce adsorbing effect between GNP and polyethylene media. Ligand Mercaptosuccinic acid (MSA) Mercaptobenzoic acid A1-3 Nylon filter A1-3.1 As nylon molecular has an amide linkage with high positive polarity in the structure. It is well known that nylon could adsorb various colloidal particles dispersing in liquid because those particles are almost negatively charged in their surface. Studies show that the ligand with amino group, which directly combines with gold surface, has a repulsive force against nylon molecular structure 3). Below table A1-2 shows the ligand examples for nylon filter evaluation. Table A1-2 Representative ligands to have an ability to reduce adsorbing effect between GNP and nylon media. Ligand 2-amino-2-hydroxymethyl-1,3-propanediol (APD) 2-amino-2-methyl-1,3-propanediol 2-amino-2-methyl-1-propanol 2-amino-1,3-propanediol 3-amino-1,2-propanediol (R)-(-)02-amino-1-propanol (S)-(+)-2-amino-1-propanol A1-4 PTFE filter A1-4.1 PTFE itself has lower surface tension and adsorbing capability; however, MSA ligand is suitable to reduce the interaction between GNP and PTFE media. A1-5 Investigation of proper ligand concentration A1-5.1 As described in this document, the ligand condition to achieve the lowest adsorbing effect is varied with membrane type. Though ligands probably some influence the membrane surface as well as challenge particle, it is uncertain that which parameter or property of membrane has an impact in regard to particle removal efficiency. However, it is supposed that pore size and surface etc. are key parameter in order to conduct at proper condition. A1-5.2 Thus, it is necessary to examine proper condition in advance. Please refer to following example showing particle penetration ratio is varied with ligand concentration. Page 10 Doc. 5421A SEMI

11 A (Example 1) A Filter type: Polyethylene Membrane sheet, 47 mm in diameter A Challenge GNP specification : 10 nm 2.9E+10 pcs/ml A Ligand MSA mmol/l, MSA solution was added to GNP solution. A Filtration was performed by challenging with GNP solution containing MSA after prewetting the membrane with Isopropyl alcohol at a flow rate of 5 ml/min. The schematic diagram of filtration equipment is shown in Figure A1-2. Figure A1-3 shows that the penetration ratio of 10 nm GNP through polyethylene membrane. The penetration ratio increased with an increase of MSA concentration. On the contrary, the gradual decrease of the penetration ratio was observed at more than 0.3 mmol/l of MSA concentration. In this case, around 0.2 mmol/l of MSA concentration is suitable to achieve the lowest adsorbing effect between GNP and membrane surface. Figure A1-2 The schematic diagram of the filtration equipment installed with 47 mm in diameter disk membrane. Page 11 Doc. 5421A SEMI

12 Figure A1-3 The penetration ratio of 10 nm GNP through polyethylene membrane. At around 0.2 mmol/l of MSA concentration, the highest penetration ratio could be observed. A (Example 2) A Filter type: Nylon6, 6 membrane sheet, 47 mm in diameter A Challenge GNP specification : 5 nm 2.5E+11 pcs/ml A Ligand APD mmol/l, APD solution was added to GNP solution. A Filtration was performed by challenging with GNP solution containing APD after prewetting the membrane with Isopropyl alcohol at a flow rate of 5 ml/min. Figure A1-4 shows that the penetration ratio of 5 nm GNP through nylon6,6 membrane. The penetration ratio was at constant at more than 0.05mmol/l of APD concentration. Page 12 Doc. 5421A SEMI

13 Figure A1-4 The penetration ratio of 5 nm GNP through nylon6,6 membrane. A (Example 3) A Filter type: PTFE membrane sheet, 47 mm in diameter A Challenge GNP specification : 10 nm 2.9E+9 pcs/ml A Ligand MSA mmol/l, MSA solution was added to GNP solution. A Filtration was performed by challenging with GNP solution containing MSA after prewetting the membrane with Isopropyl alcohol at a flow rate of 5 ml/min. Figure A1-5 shows that the penetration ratio of 5 nm GNP through PTFE membrane. Page 13 Doc. 5421A SEMI

14 Figure A1-5 The penetration ratio of 10 nm GNP through PTFE membrane. A1-6 Filter pretreatment A1-6.1 Ligands shall be injected into UPW main line. It is expected to have an effect of filter pretreatment decreasing adsorbing effect before GNP challenge test. Also, stabilizing effect of GNP solution could be expected when injecting GNP into main line. Please refer to SEMI C82 for more information. A1-7 Hydrodynamic diameter of GNP dispersed in challenge solution A1-7.1 Figure A1-6 and A1-7 shows the hydrodynamic diameter of 30nm-GNP dispersed in the solution containing MSA and APD ligand, respectively. 1.0E+8 pcs/ml of GNP solution with a variety of MSA concentration were prepared, and the hydrodynamic diameter was measured with DLS. Page 14 Doc. 5421A SEMI

15 Figure A1-6 The hydrodynamic diameter of 30nm-GNP dispersed in MSA ligand solution with a variety of the ligand concentration. Figure A1-7 The hydrodynamic diameter of 30nm-GNP dispersed in APD ligand solution with a variety of the ligand concentration. A1-8 References A1-8.1 G. Schmid, Nanoparticles From Theory to Application, Wiley-Vch Verlag GmbH & Co. KgaA (2004). A1-8.2 G. T. Hermanson, Bioconjugate Techniques, Elsevier (2008). A1-8.3 T. Mizuno et al., A novel filter rating method using less than 30-nm gold nanoparticle and protective ligand, IEEE/TSM, vol. 22, No. 4, (2009) Page 15 Doc. 5421A SEMI

16 APPENDIX 2 Particle size of NIST Reference Material NOTICE: The material in this Appendix is an official part of SEMI [designation number] and was approved by full letter ballot procedures on [A&R approval date]. A2-1 Particle size of NIST Reference Material (RM) A2-1.1 Table A2-1 and A2-2 summarize reference value mean size and expanded uncertainty of RM8011 and RM8012. Table A2-1 Reference value mean size and expanded uncertainty of RM8011 (10 nm) Technique Analyte Form Mean Particle size (nm) Expanded Uncertainty Atomic Force Microscopy Dry, deposited on substrate 8.5 ± 0.3 Scanning Electron Microscopy Dry, deposited on substrate 9.9 ± 0.1 Transmission Electron Microscopy Dry, deposited on substrate 8.9 ± 0.1 Differential Mobility Analysis Dry, aerosol 11.3 ± 0.1 Dynamic Light Scattering Liquid suspension 13.5 ± 0.1 Small-Angle X-ray Scattering Liquid suspension 9.1 ± 1.8 Table A2-2 Reference value mean size and expanded uncertainty of RM8012 (30 nm) Technique Analyte Form Mean Particle size (nm) Expanded Uncertainty Atomic Force Microscopy Dry, deposited on substrate 24.9 ± 1.1 Scanning Electron Microscopy Dry, deposited on substrate 26.9 ± 0.1 Transmission Electron Microscopy Dry, deposited on substrate 27.6 ± 2.1 Differential Mobility Analysis Dry, aerosol 28.4 ± 1.1 Dynamic Light Scattering Liquid suspension 28.6 ± º scattering angle (backscatter) Dynamic Light Scattering Liquid suspension 26.5 ± º scattering angle Small-Angle X-ray Scattering Liquid suspension 24.9 ± 1.2 Page 16 Doc. 5421A SEMI

17 APPENDIX 3 Actual filtration data NOTICE: The material in this Appendix is an official part of SEMI [designation number] and was approved by full letter ballot procedures on [A&R approval date]. A3-1 Actual filtration data A3-1.1 Actual filtration results are summarized in Table A3-1. Table A3-1 Actual filtration result (Examples) Filter / Filter size/ Lot number Polyethylene A / disk Nylon B / disk PTFE C / cartridge Average GNP size (nm) and coefficient 10nm, < 10% 20nm, < 20% 20, < 20% variation (%) GNP manufacturer/ Lot number A A A GNP concentration (N/ml) 2.9E+9 3.5E+8 3.5E+7 Water resistivity (MΩ) Water temperature ( ) Challenging time (min) Ligand / Ligand concentration (mmol/l) MSA / 0.5 APD / 1.0 MSA / 6.7E-3 Main Flow rate 5 ml/min 5 ml/min 10 L/min Side flow rate L/min Flux (ml/min/cm 2 ) ICP-MS manufacturer/ Model number A A A Background Average (ppb) < DL < DL < DL Upstream Average (ppb) Downstream Average (ppb) Efficiency (%) 94.5 > LRV (-) 1.3 > NOTICE: SEMI makes no warranties or representations as to the suitability of the Standards and Safety Guidelines set forth herein for any particular application. The determination of the suitability of the Standard or Safety Guideline is solely the responsibility of the user. Users are cautioned to refer to manufacturer s instructions, product labels, product data sheets, and other relevant literature, respecting any materials or equipment mentioned herein. Standards and Safety Guidelines are subject to change without notice. By publication of this Standard or Safety Guideline, SEMI takes no position respecting the validity of any patent rights or copyrights asserted in connection with any items mentioned in this Standard or Safety Guideline. Users of this Standard or Safety Guideline are expressly advised that determination of any such patent rights or copyrights, and the risk of infringement of such rights are entirely their own responsibility. Page 17 Doc. 5421A SEMI