Hello,
I’d like to know if we can use footwear with SD10 Static Dissipative certification, or how can we link Footwear Product Qualification for Footwear (STM 9.1) with SD10?
Can it be tailored based on the Footwear/Flooring system internal product qual done at the site maybe?
Thank you!
Santiago,
I am unfamiliar with SD10 so I am unsure how the resistance of the shoe is measured. Certainly someone, like yourself, could come to the working group meetings of the ESDA and propose SD10 be added to STM9.1. Perhaps a tailoring statement could be used to use the SD10 certification if it can be shown to be equivalent.
The ASTM standard F2413 is used to measure the electrical resistance of a shoe. The SD10 designation indicates that the resistance of the shoe is between 1 and 10 Megohms. I am not sure how that test is made and under what conditions so I cannot comment any further without reviewing the document.
A case can be made that the footwear is “qualified” per this standard, but there still needs to be body voltage measurements taken to ensure that there is no charging above 100 volts.
thanks @JohnK,
So just to understand, so i can take this as a “qualified” since it complies with F2413, but I will need to do the 97.2, right?
First, you need to make sure that the F2413 test is equivalent to ANSI/ESD STM 9.1. I don’t have that standard and I can’t comment on it. If it is equivalent, then you just need to do 97.2.
Thanks @JohnK , here some info about it (Based on AI check, let’s assume is real but I’ll check that if your approach is beneficial for us based on this scenario): the conclusion is that they are not 100% equivalent, but ASTM F2413 SD10 has a highest level of ESD protection for sensitive micro-electronics.
My question would be: How do I add this within my program to tailor my 9.1 based on this one?
.
.
.
This is the most significant physical difference in how the current is passed through the shoe.
Even if the “SD 10” shoe is tested under both standards, the “Passing” window changes.
| Feature | ASTM F2413 (SD 10) | ANSI/ESD STM 9.1 |
|---|---|---|
| Lower Limit | $1.0 \times 10^6 \Omega$ ($1 M\Omega$) | $1.0 \times 10^5 \Omega$ ($0.1 M\Omega$) |
| Upper Limit | $1.0 \times 10^7 \Omega$ (10 $M\Omega$) | $1.0 \times 10^9 \Omega$ (1,000 $M\Omega$) |
The Conflict: * A shoe that passes STM 9.1 at $500 M\Omega$ would FAIL an ASTM F2413 “SD 10” test (because it is too resistive).
The “stress” put on the material during the test is different:
Static electricity is the enemy of dry air. Both standards require “pre-conditioning” the shoes, but the targets differ:
They are not 100% equivalent. If you are looking for a shoe that meets the highest level of ESD protection for sensitive micro-electronics, you want a shoe that passes ASTM F2413 SD 10 specifically because its upper limit ($10 M\Omega$) is 100 times more conductive than the maximum allowed by STM 9.1 ($1,000 M\Omega$).
Essentially, SD 10 is a “high-performance” subset of what STM 9.1 allows.
Sound resonable, just keep the documentation in case you are asked about it. Then do the 97.2 testing.
Just document a tailoring statement in the ESD control program or have a spearate report that you file with your product qualificaiton data.
As the chair for both ESDA Standards Working Group 9 – Footwear and Working Group 97 – Footwear/Flooring, I would like to provide some clarification regarding the distinctions and requirements related to SD (Static Dissipative) footwear standards and test methods.
ANSI/ESDA S20.20 – Protection of Electrical and Electronic Parts, Assemblies, and Equipment specifies limits for both footwear and footwear/flooring system but does not prescribe the test methods. The relevant test methods are found in ANSI/ESD STM9.1 – Footwear and Foot Grounders Resistive Characterization, ANSI/ESD STM97.1 – Footwear/Flooring – Resistance Measurement in Combination with a person, and ANSI/ESD STM97.2 – Footwear/Flooring System – Voltage Measurement in Combination with a Person.
ASTM F2413 – Standard Specification for Performance Requirements for Protective (Safety) Toe Cap Footwear specifies limits for safety footwear but does not prescribe the test methods. The relevant test methods are found in ASTM F2412 – Standard Test Methods for Foot Protection.
ASTM F2412 does not provide a test method specifically for SD footwear alone. The test methods for footwear only in ASTM F2412 are designated for CD (Conductive) and EH (Electrical Hazard) types. As such, there is no test method in ASTM F2412 that directly compares to ANSI/ESD STM9.1.
ANSI/ESD STM 9.1 encompasses two tests. The first is for foot grounders, utilizing a cylindrical electrode weighing 2.27 kg ± 0.06 kg (5 lbs.) and a diameter of 63.5 mm ± 3 mm, with a contact surface made of electrically conductive elastomer (such as rubber) with a Shore-A durometer hardness between 50 and 70 as specified in ASTM D2240. This electrode is meant for foot grounders only. The second test is for footwear (shoes), which requires bags or socks flexible enough to conform to the inside of the footwear when filled with a minimum of 11.35 kg of metal shot (number 6 or finer). Footwear and foot grounders are tested in their new, unworn state.
ASTM F2412 does not specify a weight for the solid conductive metal spheres used in testing. The spheres are required to be between 3 mm and 5 mm in size, placed inside the footwear to cover the entire interior surface to a depth of no less than 30 mm (1.2 in). This test applies only to CD (conductive) and EH (electrical hazard) footwear. The document does not include a test method for SD footwear by itself.
There is footwear available on the market that is labeled solely as SD (Static Dissipative). While this type of footwear meets the requirements set forth by ANSI/ESD S20.20 and meets the limits in ASTM F2413. It is important to note that the three footwear designations within ASTM F2413 also fulfill the requirements outlined in ANSI/ESD S20.20.
ANSI/ESD STM9.1 and ANSI/ESD STM97.1 contain no limits as they are in ANSI/ESD S20.20, which is <1 x 10e9 ohms for both Footwear and Footwear/Flooring System, there is no lower limit.
ASTM F2413 has the limits for SD footwear/person system test: SD 10 has a lower limit of 1 x 10e6 ohms and upper limit of 1 x 10e7 ohms, SD 35 has a lower limit of 1 x 10e6 ohms and upper limit of 3.5 x 10e7 ohms, and SD 100 has a lower limit of 1 x 10e6 ohms and upper limit of 1 x 10e8 ohms. There is no test method for SD footwear only in ASTM documents
ANSI/ESD STM9.1 and ANSI/ESD STM97.1 test methods use 10 volts for resistance < 1.0 x 10e6 ohms and 100 volts for resistance ≥ 1.0 x 10e6 ohms.
ASTM 2412 test method for CD (conductive) footwear only, the test method utilizes a 500 volt regulated DC power supply with a current rating of 5mA or higher.
ASTM 2412 test method for EH (electrical hazard) footwear only, the test method uses a 0.5 kVA (500 VA) transformer. The procedure starts at nearly 0V and increases the voltage at a rate of 1 kV per second up to 18 kV at 60 Hz, maintaining this voltage for one minute.
ANSI/ESD STM97.1 is the test method for footwear/flooring system. The person wears footwear and stands on ESD flooring. Annex C in this document has a test method for footwear/person system that has the person wearing footwear and stands on metal plate
The ASTM F2412 only test method for SD footwear is a footwear/person system test. The person wears footwear and stands on a metal plate, which is somewhat similar to the procedure described in ANSI/ESD STM97.1 Annex C. The test is conducted using a fixed 50 volt power supply with a current limit of 5mA, connected in series with a 1 Megohm resistor and the person wearing the footwear. Consequently, the voltage applied to the person is less than 50 V.
ASTM F2412 specifies that only the specimens are to be conditioned in a controlled atmosphere for 24 hours, with testing performed at standard conditions of 22° C (±2° C) and 50% RH (±5%). There is no mention of 15% Relative Humidity in the document.
ANSI/ESD STM9.1, ANSI/ESD STM97.1, and ANSI/ESD STM97.2 require the conditioning of footwear and testing to be conducted in a controlled environment of 12% ±3% RH at 23° C ±3° C.
The correct test method used to compare footwear designated SD 10, SD 35, and SD 100 in ASTM F2413 are those established in ANSI/ESD STM97.1, which measures resistance in combination with a person. It is important to understand the flooring that is being used in conjunction with the footwear/person system and importance to perform the required test method in ANSI/ESD STM 97.2.
Warm Welcome to Daleparkin Sir - chair for both ESDA Standards Working Group 9 – Footwear and Working Group 97 – Footwear/Flooring, and Greetings of the day from India. 
Sir,
Thank you for your valuable and detailed information on comparison between the different standards , test methods and specifications followed globally on ESD footwear and footwear- flooring system.
We welcome many more such information from all the ESDAs WGs
Thank you again 
Greetings of the day from India
Very nice
Good data presentation.
JK sir has rightly advised . "keep the documentation"