Sulfur in ESD Mat

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DAVEF: In "Soldermask - sulfur presence" [ ... - Nov 29, 2017 by truthseeker

Jez, you're digging away in the grass on this one. Long time... - Nov 29, 2017 by davef

Thx for following up. We have a small PCB in a defense appli... - Nov 29, 2017 by truthseeker

Yes, "corrosion" should be on your buyers spec for ESD mats... - Nov 29, 2017 by davef

truthseeker

#79403

Sulfur in ESD Mat | 29 November, 2017

DAVEF: In "Soldermask - sulfur presence" [http://www.smtnet.com/Forums/index.cfm?fuseaction=view_thread&CFApp=1&Thread_ID=16291&#Message66659], how did you determined that sulfur was coming out of mats onto boards?

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davef

#79404

Sulfur in ESD Mat | 29 November, 2017

Jez, you're digging away in the grass on this one. Long time ago.

Look at: FED-STD-101, Method 3005 for reducible sulfur. The standard is maintained by some packing material group. Interestingly, it's not uncommon to see it referenced in other electronic manufacturing spec, like for packaging SMT components.

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truthseeker

#79405

Sulfur in ESD Mat | 29 November, 2017

Thx for following up. We have a small PCB in a defense application that has copper sulfide issues. We are using Ion chromotagraphy to track down varions ionic species including sulfates. Your post was a aha moment for me. We have a sample being analyzed this week. Ill let you know how it goes.

Thx

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davef

#79406

Sulfur in ESD Mat | 29 November, 2017

Yes, "corrosion" should be on your buyers spec for ESD mats. ESD mats are another one of those sneaky little gotcha things, where it's easy to think that all blue mats are the same. Kapon tape is another one where you can't purchase strictly based on price.

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