Background Statement for SEMI Draft Document 5428A

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Background Statement for SEMI Draft Document 5428A

NEW STANDARD: SPECIFICATION FOR IMPURITIES IN POLYETHYLENE PACKAGING MATERIALS FOR POLYSILICON FEEDSTOCK

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

Polyethylene(PE)packaging material is used to pack high purity polysilicon. The quality of Polyethylene(PE) bags is critical as poor quality PE bags may contaminatepolysilicon and cause contamination during transportation.

Despite the importance of PE packaging material, however, there currently is no industry-consensus standard in the Photovoltaic industry for PE material.Forming an industry-consensus standard will minimize contamination and associated costs and improve communication between supplier and user.

Review and Adjudication Information

Task Force Review / Committee Adjudication
Group: / Poly-Silicon Packaging Materials Task Force / China PV Committee
Date: / TBD / Oct.23th, 2013
Time &Timezone: / TBD / 9AM—5PM & China
Location: / TBD / Worldhotel Grand Juna Wuxi
City, State/Country: / China / China
Leader(s): / Jinbiao Lv (GCL)
Xiaoxia Liu( GCL)
Binglin Lu(CPRTC) / Guangchun Zhang(CanadianSolar)
Jun Liu(CESI)
Standards Staff: / Kris Shen(SEMI China)
/ Kris Shen(SEMI China)

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 Poly-Silicon Packaging Materials TF Leader.

Xiaoxia Liu/ GCL

Tel: +86 516 85868888-88500
E-mail:

Or contact SEMI Staff, Kris

SEMI Draft Document 5428A

NEW STANDARD: SPECIFICATION FOR IMPURITIES IN POLYETHYLENE PACKAGING MATERIALS FOR POLYSILICON FEEDSTOCK

1 Purpose

1.1 This specification is intended for the quality and the testing method of Polyethylene (PE) bags. The quality of PE bags is critical as poor quality PE bags may contaminate polysilicon and cause contamination during transportation. Forming an industry-consensus standard will minimize contamination, controlthe associated costs and improve communication between supplier and user.

2 Scope

2.1 This standard will cover the quality criteria and the associated test method for impurities contained in PE bags used for polysilicon feedstock packaging. The size and the metal impurities (Al, Zn, Na, Ca, K, Ni, etc.) on both surface and in the body of the bagare defined in this document.

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 ISO Standards[1]

ISO 291:1997— Plastics — Standard Atmospheres for Conditioning and Testing

ISO 527—Plastics — Determination of Tensile Properties

ISO 8296—Plastics — Film and Sheeting-Determination of Wetting Tension

ISO 14782—Plastics — Determination of Haze for Transparent Materials

ISO 15105—Plastics — Film and Sheeting-Determination of Gas-transmission rate

ISO 15106—Plastics — Film and Sheeting-Determination of Water VaporTransmission Rate

4.2 ASTM Standards[2]

ASTM E122—Standard Practice for Calculating Sample Size to Estimate, With Specified Precision, the Average for a Characteristic of a Lot or Process

4.3 ANSI/ASQCStandards3

ANSI/ASQC Z1.4-1993—Sampling Procedures and Tables for Inspection by Attributes.

NOTICE: Unless otherwise indicated, all documents cited shall be the latest published versions.

5 Terminology

5.1 Abbreviations and Acronyms

5.1.1 ICP-MS— Inductively coupled plasma mass spectrometry

5.1.2 PE — Polyethylene

6 Test Methods

6.1 Appearance — By eye-measurement

6.2 Dimensions —By tape measure or flexible rule, etc.

6.3 Physical properties—It shall be in accordance with ISO 527, ISO 15105, ISO 15106, ISO 14782, and ISO 8296;

6.4 Surface impurities contamination —In accordance with Appendix 1.

6.5 Bulk impurities contamination —In accordance with Appendix 2.

7 Requirements

7.1 Appearance —films shall be visibly free of flaws, wrinkles, stains, foreign matter or any marks that impair its serviceability.

7.2 The splicing of two films in a roll shall be prominently marked in order to provide a visible indication from the side of the roll. The interested parties shall agree upon the method of marking the splice.

7.3 Dimensions

7.3.1 General

7.3.1.1 For any individual film selected at random from any delivery, the dimension listed in § 7.3.2 to § 7.3.5, including their nominal values, shall be agreed upon among interested parties.

7.3.2 Width

7.3.2.1 The tolerance of width of the films shall be within4mm.

7.3.2.2 An example of film width with corresponding tolerance is given in Table 1.

Table 1Example of AFilmWidth and Tolerance

Width
mm / Tolerance
mm
500+40n#1 / +4
0

#1n:integer,0,1,2,…In width steps of 40 mm.

7.3.3 Length of Film in Roll

7.3.3.1 The tolerance of film length in a roll shall be within +10%of the nominal value.

7.3.3.2 Examples of film length and corresponding tolerance in a roll are shown in Table 2.

Table 2Examples of Film Length in Roll and Their Tolerance

Length of film / Tolerance of length of film
m
Nominal length
m / Length in roll
km
4000 / 4 / +40
0
6000 / 6 / +60
0
8000 / 8 / +80
0
>8000 / >8 / 1% of nominal length

7.3.4 Inside Diameter of Core of Roll

7.3.4.1 The inside diameter tolerance of a core of a roll shall be within +20mm of the nominal value.

7.3.4.2 Examples of inside diameter of core in a roll, and corresponding tolerance are given in Table 3

Table 3Examples of Inside Diameter of ACore in ARoll and Their Tolerances

Inside diameter of core
mm / Tolerance on inside diameter of core
mm
76 / +2
0
152 / +2
0

7.3.5 Thickness

7.3.5.1 The thickness tolerance shall be within ±10% of the nominal value.

7.3.5.2 Examples of thickness and corresponding tolerance are given in Table 4

Table 4Examples of Thickness and Their Tolerance

Thickness / Tolerance
μm
Nominal
No. / Thickness
μm
12 / 12 / ±1.2
16 / 16 / ±1.6
25 / 25 / ±2.5

7.4 Physical Properties

7.4.1.1 Films shall meet the requirements for physical properties listed inTable 5.

Table 5Properties of Film

Properties / Unit / Test method / Requirements
Longitudinal#1 / Transverse#2
Dimensional change heating / % / ISO 15988 / ≤3 / ≤3
Coefficient of oxygen transmission / foml.100μm/
(m2·s·pa) / ISO 15105-1 or
ISO 15105-2 / ≤140
Coefficient of watervapor transmission #4 / g/100μm/
(m2·24h) / ISO 15106-1,
ISO 15106-2 or
ISO 15106-3 / ≤10
Wetting tension#5 / mN/m / ISO 8296 / ≥40

#1Longitudinal :direction parallel to extrusion or “machine direction”

#2Transverse:direction perpendicular to extrusion.

#323℃,0% relative humidity.

#440℃,90% relative humidity.

#5The wetting tension shall only apply to films with corona discharge

7.5 Surface Impurities Contamination

7.5.1 The total content of 15 elements impurities (B、Na、Mg、Al、P、K、Ca、Cr、Mn、Fe、Ni、Cu、Zn、As、Pb) on the surface of PE material ≤20ppbw

7.6 BulkImpurities Contamination

7.6.1 The total content of 15 elements impurities (B、Na、Mg、Al、P、K、Ca、Cr、Mn、Fe、Ni、Cu、Zn、As、Pb) in the body of PE material≤1000ppbw

8 Sampling

8.1 The atmosphere when Polyethylene packaging material is tested should be in accordance withISO 291:1997

8.2 Unless otherwise specified, samplingshould be in accordance with ASTM E122. When specified, appropriate sample sizes shall be selected from each lot in accordance with ANSI/ASQC Z1.4-1993. Inspection levels shall be agreed upon between the supplier and the purchaser.

9 Certification

9.1 Upon request of the purchaser in the contract or order, a manufacturer’s or supplier’s certification wherethe material was manufactured and tested in accordance with the specification should be furnished at the time of shipment (Certificate of Compliance). Upon request, a report of the test results may also be required (Certificate of Analysis).

10 Package and Package Labeling

10.1 Packaging and size of unit packaging shall be agreed upon between the supplier and the customer.

10.2 The following shall be clearly marked on the package:

10.2.1 Name of products of symbol;

10.2.2 Classification of film, whether treated corona discharge or not;

10.2.3 Nominal thickness ,width and length of a roll;

10.2.4 Year and month of manufacture;

10.2.5 Name of manufacture or symbol.

11 Related Document

ISO 15988:2003— Plastics— Film and sheeting —BiaxiallyOriented Poly (ethylene terephthalate) (PET) Films

APPENDIX 1

TEST METHOD FOR THE SURFACE METAL CONCENTRATION OF POLYETHYLENE PACKAGING MATERIALS FOR POLYSILICON FEEDSTOCK

NOTICE: The material in this Appendix is an official part of SEMI Doc. 5428 and was approved by full letter ballot procedures on [A&R approval date].

A1-1 Procedure

A1-1.1 Choose one 20-piecespackage of PE material from a lot to be sampled.

A1-1.2 Deliver the bag to the clean room for sampling.

A1-1.3 Choose onepiecerandomly from the package as the lot sample.

A1-1.4 Then cut out 6 small pieces which must be taken from the different location of the piece. Each small piece shall be with an approximate size of 5 by 5cm.If the sample must be taken in a location other than the analytical laboratory, seal the sample in double bags and send to the laboratory. To minimize contamination from the room environment and the analyst, all sample collection andanalysis steps are carried out in a clean room and laminar flow hood, with analysts in full clean room attire. A minimum of a Class 6 clean room, as established in ISO 14644–1, is required to minimize interferences from environmental sources. In the laboratory, open the double bag according to standard clean room practice and transfer the pieces to a clean, numbered PFAbeaker and weigh to four decimal places.

A1-1.5 Add about 10 ml5% nitric acid etching mixture to each beaker to cover the pieces and seal with PFA lids.

A1-1.6 Place the sealed beakers onto the hot plate in the fume hood and heat for about 60 min at about 70°C. Remove from heat and cool, then remove each piece with PTFE tongs, rinsing the surface with DI water into the beaker, weigh the beakers with the solution in.

A1-1.7 Along with the samples, prepare at least 2 digest blanks.

A1-1.8 Prepare appropriate calibration standards, control standards.

A1-1.9 Load samples and standards into the ICP-MS instrument sample carrousel tray.Each run shall include the following:

• Acid blank,
• Calibration standards,
• Control standards,
• DI water,
• First digested blank,
• Lot samples.
• Choose and record the instrument parameters, according to the instrument manufacturer's instructions, for the sample measurement.

1. Calculation
2. Calculate the results as follows:

M= (I− B)×(m-m0)(A1-1)

where:

M= concentration of analyte, ,

I= instrument reading of analyte, ppbw,

B= instrument reading of average of two blanks, ppbw,

m = weight of the beakers with solution after etching, gram,

m0 = weight of the beakers without solution, gram.

APPENDIX 2

TEST METHOD FOR THE BULK METAL CONCENTRATION OF POLYTHYLENE PACKAGING MATERIALS FOR POLYSILICON FEEDSTOCK

NOTICE: The material in this Appendix is an official part of SEMI Doc. 5428 and was approved by full letter ballot procedures on [A&R approval date].

A2-1 Procedure

A2-1.1 Choose one 20-piecespackage of PE material from a lot to be sampled.

A2-1.2 Deliver the bag to the clean room for sampling.

A2-1.3 Choose onepiecerandomly from the package as the lot sample.

A2-1.4 Then cut out 3 small pieces which must be taken from the different location of the piece. Each small piece shall be with an approximate weight of 1g.

A2-1.5 Clean them with DI water. Using ceramic scissors, cut them small piece with aapproximate size of 2mm*10mm.

A2-1.6 Put the small pieces of PE with an approximate weight of 1g into a digestion tank,

A2-1.7 Add about 10 mlnitric acid etching mixture to each tank.

NOTE: Steps above are suggested to be done in the cleanroom to avoid contamination.

A2-1.8 Seal the tanks, then put them into the micro digestion system.

A2-1.9 After digestion, cool and transfer them back into the cleanroom.

A2-1.10 Open the tank, transfer the solution into a 25ml volumetric flask, rinse the tank with DI water more than 2 times into the volumetric flask, dilute with DI water to volume, and mix.

A2-1.11 Along with the samples, prepare at least 2 digest blanks.

A2-1.12 Prepare appropriate calibration standards, control standards.

A2-1.13 Load samples and standards into the ICP-MS/ICP-OES instrument sample carrousel tray.Each run shall include the following:

• Acid blank,
• Calibration standards,
• Control standards,
• DI water,
• First digested blank,
• Lot samples.
• Choose and record the instrument parameters, according to the instrument manufacturer’s instructions, for the sample measurement.

1. Calculation
2. Calculate the results as follows:

M= (I− B)×V/m0(A2-1)

where:

M= concentration of analyte, ng/g,

I= instrument reading of analyte, ng/ml,

B= instrument reading of average of two blanks, ng/ml,

V= volume of the solution after dilution, ml,

m0 = weight of the sample to be digested in the tank, gram.

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.

This is a Draft Document of the SEMI International Standards program. No material on this page is to be construed as an official or adopted Standard or Safety Guideline. Permission is granted to reproduce and/or distribute this document, in whole or in part, only within the scope of SEMI International Standards committee (document development) activity. All other reproduction and/or distribution without the prior written consent of SEMI is prohibited.

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