Background Statement for SEMI Draft Document 5659

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Background Statement for SEMI Draft Document 5659A

New Standard: Test Method Based on RGB for C-SI Solar Cell Color

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:

At present, C-Si solar cell is the most important product in solar industry. However, there is a difference in front surface color of the cells due to the different equipments and processes. Once the cells of different colors made into a module that will be a chromatic aberration module.

In order to standardize the color-testing method for crystalline silicon solar cell, at the same time, improve the efficiency and accuracy of the test, and improve the quality of the whole industry, the standard is set.

Review and Adjudication Information

This meeting’s details are subject to change, and additional review session may be scheduled if necessary. Contact the task force leaders or Standards staff for confirmation. Check for the latest schedule.

Telephone and web information will be distributed to interested parties as the meeting date approaches. If you will not be able to attend these meeting in person but would like to participate by telephone/web, please contact Standards staff.

If you have any questions, please contact the ballot author at:

Xi Zhang/ Yingli Solar

Tel: +86. 135.8222.8029

E-mail:

Yingye Li/ Yingli Solar

Tel: +86. 137.2223.9055

E-mail:

SEMI Draft Document 5659A

New Standard: Test Method Based on RGB for C-SI Solar Cell Color

1 Purpose

1.1 The purpose of this standard is to standardize the color-testing method for crystalline silicon solar cell to improve the efficiency and accuracy of the test.

2 Scope

2.1 This standard defines the test method for crystalline silicon solar cell color.

2.2 This standard is applicable to test the crystalline silicon solar cell color by the cell color detector.

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 This standard is only applicable to the color-testing of the crystalline silicon solar cell that the printing and firing processes have been finished.

4 Referenced Standards and Documents

4.1 ISO Standard[1]

ISO105/A02—1993— Textiles -- Tests for color fastness - grey scale for assessing change in color

ISO 14644-1—1999 — Cleanroom and Associated Controlled Environments —Part 1: Classification of Air Cleanliness

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

5 Terminology

5.1 Abbreviations and Acronyms

5.1.1 C-Si— Crystalline Silicon

5.1.2 ℃—Degree Celsius

5.1.3 R — Red

5.1.4 G — Green

5.1.5 B — Blue

5.1.6 H — Hue

5.1.7 S — Saturation

5.1.8 V — Value

5.1.9 μm—Micrometer

5.1.10 CM —Camera module

5.1.11 PR—Power rack

5.1.12 IPC—Industry PC

6 Summary of Test Method

6.1 It is necessary to process the surface of cell sample, and ensure that the surface is clean and no contamination.

6.2 Cell sample should be placed below a high resolution digital camera, and exposed under the light irradiation, so it acquires digital photos and basal R, G, B color information.

6.3 Using computer software for the analysis of digital photos, and through transformation of the color model, so it acquires hue, brightness and saturation of the color parameters.

7 Apparatus

7.1 Apparatus includes Camera module (CM), Power rack (PR), Industry PC(IPC). (See Figure 1.)

Figure1

Testing setup Equipment Diagrammatic Sketch

7.2 Camera Module(CM)

7.2.1 Main Test unit is response for LED light controlling; Acquisition; Image collecting and transmission.

7.2.2 Camera is used to take photos for the cell, and its pixel size should be less than 80μm;

7.2.3 Led light is divided intofrontandback light source. The front light is used to supply stable and correct illumination for the camera during acquisition, which have red, green and blue or other wave length light, and the light source can guarantee the mean gray deviation is less than ±5% when use the white or grey board for white balance testing;

7.2.4 The back light is used to supply stable light environment for the cell edge (Geometry);

7.3 Power Rack (PR)

7.3.1 Response for supply stable power to led and camera.

7.4 Industry PC（IPC）

7.4.1 The IPC is working for the signal transmission; Image collecting; Image analysis; result output.

8 Safety Precautions

8.1 Physical Safety—Due to the high intensity of the light source, do notlook at the light source directly or wear goggles to avoid of the damage of the eyes when exposing to the light source.

9 Test Specimens

9.1 The test specimens is the crystalline silicon solar cell that the printing and firing processes have been finished, and it must be integrated, clean and no contamination on the surface.

10 Preparation of Apparatus

10.1 Because the temperature and humidness influence the test result, the test environment should meet the following condition:

10.1.1 The test environment temperature should be 25℃±2℃, the environment humidness should be from 40% to 70%;

10.1.2 Environmental cleanliness should be better thangrade 6 clean room requirements as defined in ISO 14644-1-1999 “Clean room and associated controlled environments--Part 1:Classification of air cleanliness”;

10.1.3 The platform for the cell color detector should be horizontal and kept stable.

11 Calibration and Standardization

11.1 The camerafocus calibration, vision field calibration, white balance calibration, front light source calibration and back light plate calibration are required with the special tools when first installed the cell color detector (Refer to ISO105/A02-1993).

11.2 These calibrations should be done periodically when the cell color detector is used in the process.

12 Procedure

12.1 A reliableevaluation resultrequires the measurementshould be conducted under appropriateconditions,withthemeasurement processshould be clearlydescribed in the report.(See Figure 2.)

Figure 2

Test procedure

12.1.1 System ready

12.1.2 Cell ready

12.1.2.1 Put the production cell on the table which is fit for the requirements of taking image.

12.1.3 Image acquisition

12.1.3.1 Taking image by camera with correct and stable illumination.

12.1.4 Image analysis process

12.1.4.1 Analysis the image by IPC to get current RGB values for every available pixel.

12.1.4.2 Calculate and classify the cell color result by pixels RGB value and output the result.

12.1.5 Record the related test data.

13 Calculations

13.1 Through the color model, the original R, G, B information of pixel points transform to visualized color information of pixel points, such as Hue, brightness and saturation.(Refer to ¶Appendix 1);

13.2 Transform the color information from pixel points to the whole cell by calculation formulas, such as mean value,variance of Hue,brightness and saturation.(Mainly refer to Hue, Brightness and saturation is complementary).

14 Report

14.1 The report shall contain the following element:

14.1.1 Temperature and humidity of test environment;

14.1.2 The cell color detector brand and type, reference standard;

14.1.3 The source, type and specification of the cell;

14.1.4 The mean value and variance of Hue,combined with other information of the cell color if necessary;

14.1.5 Tester, review, approval, report number;

14.1.6 Test agency, test name, test address, test date and test time.

APPENDIX 1

CALCULATION METHODS

NOTICE: The material in this Appendix is an official part of SEMI [document 5659] and was approved by full letter ballot procedures on [A&R approval date].

A1-1 There are two calculation methods as follow:

A1-1.1 Calculation Method One

A1-1.1.1 If R is the biggest and G is the smallest among R, G and B, calculate with the formula of (A1-1), (A1-2), (A1-3):

(A1-1)

(A1-2)

(A1-3)

Where:

— Red；

— Green；

— Blue；

— Hue；

— Saturation；

— Value；

A1-1.1.2 If R is the biggest and B is the smallest among R, G and B, calculate with the formula of (A1-4), (A1-5), (A1-6):

(A1-4)

(A1-5)

(A1-6)

Where:

—Red；

—Green；

—Blue；

—Hue；

—Saturation；

—Value；

A1-1.1.3 If G is the biggest and R is the smallest among R, G and B, calculate with the formula of (A1-7), (A1-8), (A1-9):

(A1-7)

(A1-8)

(A1-9)

Where:

—Red；

—Green；

—Blue；

—Hue；

—Saturation；

—Value；

A1-1.1.4 If G is the biggest and B is the smallest among R, G and B, calculate with the formula of (A1-10), (A1-11), (A1-12):

(A1-10)

(A1-11)

(A1-12)

Where:

—Red；

—Green；

—Blue；

—Hue；

—Saturation；

—Value；

A1-1.1.5 If B is the biggest and R is the smallest among R, G and B, calculate with the formula of (A1-13), (A1-14), (A1-15):

(A1-13)

(A1-14)

(A1-15)

Where:

—Red；

—Green；

—Blue；

—Hue；

—Saturation；

—Value；

A1-1.1.6 If B is the biggest and G is the smallest among R, G and B, calculate with the formula of (A1-16), (A1-17), (A1-18):

(A1-16)

(A1-17)

(A1-18)

Where:

—Red；

—Green；

—Blue；

—Hue；

—Saturation；

—Value；

A1-1.2 Calculation Method Two

(A1-19)

(A1-20)

(A1-21)

(A1-22)

(A1-23)

(A1-24)

Where：

—Luminance;

—Chroma;

—Concentration;

—Red；

—Green；

—Blue；

—Hue；

—Saturation；

—Value

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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