Crystalline Silicon PV Module China PV Committee

Transcription

1 Background Statement for SEMI Draft Document 5385 NEW STANDARD: TEST METHOD FOR THE CONTENT OF VINYL ACETATE(VA) IN ETHYLENE-VINYL ACETATE(EVA) APPLIED IN PV MODULES USING THERMAL GRAVIMETRIC ANALYSIS(TGA) 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: Poly ethylene-vinyl acetate (EVA) is one of the important encapsulation materials in photovoltaic modules. Besides the cost, the quality and the life span of the photovoltaic products are important factors to be considered when choosing the appropriate EVA. EVA performance mainly depends on its molecular weight and the content of Vinyl Acetate (VA). When the molecular weight of EVA is constant, the elasticity, softness, cohesiveness, compatibility and transparency of EVA will change correspondingly with the change of VA content. Therefore, it is critical in having accurate test of VA content in EVA. This standard addresses the needs to develop an effective method to test for VA content in EVA using thermo gravimetric analysis (TGA). Review and Adjudication Information Task Force Review Committee Adjudication Group: Crystalline Silicon PV Module China PV Committee TF Date: TBD March 18 th, 2013 Time & Timezone: TBD TBD Location: TBD Kerry Hotel, Shanghai, China City, State/Country: China Shanghai, China Leader(s): Standards Staff: Wei Zhou / Trina Solar Cheng Zhu/ Suntech Qiang Huang /Trina Solar Binglin Lu/CPRTC Kris Shen(SEMI China) Guangchun Zhang(CanadianSolar) Jun Liu(CESI) Kris Shen(SEMI China) kshen@semi.org kshen@semi.org Meeting date and time are subject to change, and additional TF review sessions may be scheduled if necessary. Contact the task force leaders or Standards staff for confirmation. Check for the latest schedule. If you have any questions, please contact the ballot author at: Taoyun Xiao/ Trina Solar Tel: taoyun.xiao@trinasolar.com

2 SEMI Draft Document 5385 NEW STANDARD: TEST METHOD FOR THE CONTENT OF VINYL ACETATE(VA) IN ETHYLENE-VINYL ACETATE(EVA) APPLIED IN PV MODULES USING THERMAL GRAVIMETRIC ANALYSIS(TGA) 1 Purpose 1.1 The purpose of this standard is to standardize a fast and accurate test method for the content of vinyl acetate (VA) in poly ethylene-vinyl acetate (EVA) using thermal gravimetric analysis (TGA) method. 2 Scope 2.1 This test method characterizes the VA content of EVA in photovoltaic modules. 2.2 This test method covers the VA content test using a TGA instrument. 2.3 This test method is intended for the EVA film. 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 None. 4 Referenced Standards and Documents 4.1 None 5 Terminology 5.1 Refer to the SEMI Standards Compilation of Terms (COTs) for a list of the current Abbreviations, Acronyms, Definitions, and Symbols. 5.2 Abbreviations and Acronyms degrees Celsius EVA ethylene-vinyl acetate g gram(s) m milli Min minute(s) VA vinyl acetate. 5.3 Definitions TGA Thermal gravimetric analysis is a method where a sample is placed in a certain environment where the temperature is changed and the resulting change in weight is measured. Weight change is also observed when decomposition, combination, desorption, absorption, dehydration or sublimation occur WL% The sample weight loss percentage in the first stage, as shown in Figure 1. Page 1 Doc SEMI

3 6 Summary of Test Method Figure 1 Diagram of the Sample Weight Loss Percentage in the First Stage 6.1 The thermal gravimetric analysis (TGA) method measures the relationship between the quality and the temperature when the testing material is subject to temperature changes. TGA also analyzes the relationship between weight and time in constant temperature conditions where it can be used to characterize any material that exhibits a weight change and to detect phase changes due to decomposition, oxidation, or dehydration. 6.2 A small sample is prepared before the instrument test. 6.3 The process for raising temperature is carried out by the TGA instrument, and the relationship between weight change and temperature is analyzed. 6.4 The VA content is calculated according to the weight loss and the ratio of molecular weight. WL% 7 Apparatus 7.1 Following major components are included by the TGA instrument: Balance The key component of TGA instrument, used for accurate measurement of the weight of samples Heating furnace Heat the sample and control sample temperature Heat exchanger Have heat exchange function, mainly for heating furnace Purge gas flow controllers Control and measure the pure protecting gas for sweeping and cleaning the balance and furnace. 8 Reagents and Materials 8.1 Purge Gas Nitrogen (Purity: 99.99%) 9 Safety Precautions 9.1 Chemical Safety Do not use hydrogen or any other explosive gas in the heating furnace of the TGA instrument. If the samples used emit harmful gases, vent the gases by placing the instrument near an exhaust. 9.2 Thermal Safety Cool the heating furnace to below 45 before running another operation. Page 2 Doc SEMI

4 9.3 Mechanical Safety When the heating furnace is running, refraining from moving the heating furnace to ensure the sealing performance. 10 Test Specimens 10.1 Large samples should be placed in a clean, seal, marked bag. The bag should be kept in a drying vessel for more than six hours Wear clean gloves when preparing the samples. Samples should be cut in the weight range of 5 and 15 mg The small sample should be laid on the bottom of the pot during the test. 11 Preparation of Apparatus 11.1 Because of the high sensitivity of the TGA instrument, the testing environment should meet the following requirements: Environment temperature should be 25±2, environment humidity should be 50±5% Environment should be kept clean and ventilated The operation platform of the TGA instrument should be on a stable surface with no vibrations. A marble table is recommended TGA instrument precision requirements mass accuracy: 0.01mg. 12 Calibration and Standardization 12.1 Weight (Mass) Calibration Weight (Mass) calibration is required when the TGA instrument is first used in the process. Weight (mass) calibration should be done periodically Temperature Calibration Temperature calibration is required when the TGA instrument is first used in the process. Temperature calibration should be done periodically. 13 Procedure 13.1 Confirm that the TGA instrument is operational. Put the clean testing pat into the TGA instrument tare Put the small sample into the pot preparation test Initiate the TGA test procedure: Maintain constant temperature for five minutes Raise the temperature from room temperature to 600 at 10 /min heating rate Put the pot, filled with the sample, into the TGA instrument and begin the test Record the percentage of weight change rate in the first stage (as shown in figure 2). Page 3 Doc SEMI

5 First Stage Figure 2 The Curve of Weight Percentage Varies with Temperature Changing 14 Calculations 14.1 Calculation formula: (1) where: VA% The percentage of VA content in EVA WL% The percentage of the first stage loss weight in the original weight Mm The molecular weight of vinyl acetate (86) Ma The molecular weight of acetic acid(60) 15 Report 15.1 The report shall contain the following elements: Sample source and sample name; Temperature and humidity of testing environment; Gas flow and heating rate; Sample weight and weight loss percentage of the sample in the first stage; Instrument name, reference standard, and test results (contains the test cure and the calculation results); Tester, review, approval, and report number; Testing agencies, testing name, and testing address. Page 4 Doc SEMI

6 NOTICE: Semiconductor Equipment and Materials International (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 5 Doc SEMI