SEMI International Standards
SEMI New Activity Report Form (SNARF)

Activity Number: 5385
SNARF for: New Standard: Test Method for the content of Vinyl Acetate (VA) in Ethylene-Vinyl Acetate (EVA) applied in PV modules—Thermal Gravimetric Analysis (TGA)

Originating Global Technical Committee: Photovoltaic
Originating Technical Committee Region: China
Task Force in which work is to be carried out: Crystalline Silicon PV Module Task Force

1. Rationale: EVA (poly ethylene-vinyl acetate) is one of the most important encapsulation materials in the whole photovoltaic modules and sold in varieties on the market. When choosing the appropriate EVA, it’s not only the cost but, the more important problem is quality and life for the photovoltaic manufacturer.
EVA performance depends mainly on its molecular weight and the content of VA (Vinyl Acetate). When the molecular weight is constant, with the increase of the content of VA, the elasticity, softness, cohesiveness, compatibility and transparency of EVA will improve. When the content of VA becomes low, the performance of EVA is equivalent to polyethylene.
Therefore, choosing the appropriate EVA is critical. These methods for testing the content of VA will help fill the gaps in the international standards.

Rate the Estimated Effect on the Industry
1: Major effect on entire industry or on multiple important industry sectors

Rate the Estimated Technical Difficulty of the Activity
II: Some Difficulty - Disagreements on known requirements exist but developing consensus is possible

2. Scope:
a: Define the areas to be covered or addressed by this activity or document:
This standard belongs to the photovoltaic industry. The main test methods of the proposal are as follows:
1) The Infrared spectroscopy is the most commonly used method. Series of different contents VA of the standard sample are prepared, and then standard curve is drawn. When EVA is being measured, the result VA’s content can be obtained from the standard curve. This testing method is simple but the accuracy of standard curve is not high.
2) The chemical analysis is the original method. It occurs at the saponification reaction, and then calculates the content of VA by using titration. The result of this method is always volatility, and there are many disadvantages of this method, such as maneuverability, and accuracy, etc.
3)TGA (Thermogravimetric Analysis)method is putting sample in a oven, then change the temperature, and measure the weight’s difference . When decomposition, combination, desorption, absorption, dehydration or sublimation occurs, weight fluctuation will be observed in a diagram. While heating, EVA is subjected into a series of chemical reactions. The acetic acid from EVA will be decomposed at the first step. The content of VA is calculated through the relationship between VA and acetic acid. As a result, the content of VA can be tested easy, fast and accurate.
As a result, by using TGA. test can be performed accurately and better in the same level.

b: Expected result of activity
New Standard

3. Projected Timetable for Completion:
a: General Milestones
a. Activity Start: 01/20/2012b. 1st Draft by: 09/01/2012
c. Preballot by: d. Technical Ballot by: 03/30/2013
e. Committee Approval By:08/01/2013

Safety Considerations:
The resulting document is expected NOT to be a Safety Guideline

Intellectual Property Considerations:
a. In complying with the standard or safety guideline to be developed, the use of patented technology or a copyrighted item(s) is NOT required
b. The body of the standard and any appendices or related information sections will NOT include copyrighted material

Comments, Special Circumstances: None.

Approval: Activity approved by Committee/GCS on February 6, 2012