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J-STD-001 Par 4.2.2 Temperature and Humidity

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J-STD-001 Par 4.2.2 Temperature and Humidity | 11 July, 2007

Hi folks!

Has anyone ever successfully verified adequate ESD control at <30% relative humidity to satisfy the J-STD-001 requirement? I need to be able to satisfy auditors with the solution.

Thanks in advance!

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J-STD-001 Par 4.2.2 Temperature and Humidity | 16 July, 2007

J-STD-001 doesn't necessarily require additional controls under conditions of low humidity, only that you verify the effectiveness of what you have in place. ESD S20.20 [1999] only says that relative humidity above 30% is "desirable". ESD S20.20 [2007] doesn't address the issue.

Things you could do are: * Do NOT let the humidity drop below 30% on the production floor. This is done pretty easily by using floor humidifiers. * Show that your ESD program is effect [eg, measure static buildup levels at our workstations at least twice a day and ceasing operations in any area where the static meter readings reach 200 volts, turn-on ionizers at all work stations, etc], if the humidity falls below 30%.

So, why do you suppose that the fine folk at IPC decided to use %RH, rather than dew-point?

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J-STD-001 Par 4.2.2 Temperature and Humidity | 17 July, 2007

Per ESD Handbook TR 20.20 paragraph 5.3.15 Humidity "Humidity is beneficial in all ESD Control Program Plans. Contact and separation of dry materials generates greater electrostatic charges than moist materials because moisture provides conductivity that helps to dissipate charge. For this reason, ESD effects are most noticeable in the winter since heating systems reduce building environment moisture. Geographic location (desert vs. coastland) is also a major contributor to ambient conditions inside buildings. Any circumstance that results in a low relative humidity will permit a greater accumulation of electrostatic charges. Relative humidity above 30 percent in ESD protective areas is desirable as long as other adverse conditions are not created as a result of humidity levels. Generally speaking an upper limit of 70 percent is desirable to prevent corrosive effects on the metal portions of electronic devices and assemblies. Besides the increasing propensity to generate electrostatic charges on dry materials in general, performance of many ESD protective materials degrade. In fact, when exposed to low humidity conditions, some ESD protective materials become totally ineffective or become sources of electrostatic charges. Therefore, evaluation of ESD control materials should include performance testing in controlled environments at the lowest expected operating relative humidity level. Manufacturers of ESD protective materials should be able to provide performance data in regards to relative humidity. Like wise materials should be tested in moderate humidity conditions as well to ensure they do not become "too conductive" and present a potential safety hazard to personnel working with substantial voltages. See the Personnel Safety section of this handbook for further guidance in this area. Humidity control in factories or physically large areas or buildings can be difficult and expensive. In smaller rooms or areas, it may be possible to use portable humidifiers to raise the immediate area humidity. However, in large facilities and factories the environmental systems many need to include steam generation and monitoring equipment to control humidity. This type of equipment is expensive to install and purchase especially in pre-existing facilities. To reduce the total cost impact, companies should consider the need for humidification equipment when planning new facility construction."

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J-STD-001 Par 4.2.2 Temperature and Humidity | 18 July, 2007

This seems like an odd request from an auditor. I can see an auditor requiring proof that you meet the J-Std, but verify? This would require you purposely damage product on a "before and after" scenario. As long as your manufacturing guideline says you are required to meet J-STD-001, there is no need for him to ask such a question. Proving you meet the requirement is one thing, proving you have bad results if you don't, is another.

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J-STD-001 Par 4.2.2 Temperature and Humidity | 18 July, 2007

The auditor may be using "verify" in an ESD Program context. See ANSI/ESD S20.20 [1999], 6.1.3, Compliance Verification Plan. It gives one definition of what the auditor may be seeking. For more on verification programs, look here:

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