This is an anecdote and not data, but I can speak of the reliability issue from personal experience. I don’t remember exactly when this occurred, but it was around 2005. A supplier of power cords was using red phosphorus as the flame retardant in a plastic part for the IEC 60320-C13 connector on a power cord. The phosphorous was in the rigid plastic part that supported the contacts with the softer material molded over this material. The phosphorus was not well stabilized in the plastic. Moisture led to the chemical reaction described by Mr. Woodgate, resulting in phosphoric acid. The acid attached the contact material leading to a increase in the resistance of the contact. This occurred in products that used close to the full current rating of the connector, running close to 10 A. There was enough heating in the connector that the overmold material n the C13 swelled up to the point where the connector could no longer be removed from the mating C14 connector.
This did not cause a safety issue. Temperatures remained low enough that there was no ignition. This happened on industrial products in an environment where there were no flammable materials in the vicinity of the connectors. It only resulted in a reliability issue where there the electrical connection eventually was lost and the detachable cord was no longer detachable. The final analysis determined that the supplier of the plastic part using the phosphorous didn’t have sufficient quality control to ensure that the phosphorous was properly encapsulated. Supply chains have become more complicated since then. Quality control and supply chain management are critical to avoid similar issues. Ted Eckert Microsoft Corporation The opinions expressed are my own and do not necessarily reflect those of my current employer, previous employer or the manufactures or power cords and connectors. From: Adam Dixon <[email protected]> Sent: Wednesday, January 2, 2019 7:12 AM To: [email protected] Subject: Re: [PSES] Red phosphorus flame retartants I agree that it's an older paper, but the data are still relevant IMO. Here are a few more recent ones from different US gov't organizations with a pyrology focus (so not solely focused on Scott's original question, but still informative): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5445781/<https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC5445781%2F&data=02%7C01%7Cted.eckert%40microsoft.com%7C848549be33cc46a789f608d670c4cbd8%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C1%7C636820387889239646&sdata=khPIVM4MtaFuyvZVKByb%2FeS5bwkjXLf01HImUBIZNhE%3D&reserved=0> https://www.epa.gov/sites/production/files/2015-08/documents/pcb_ch1.pdf<https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.epa.gov%2Fsites%2Fproduction%2Ffiles%2F2015-08%2Fdocuments%2Fpcb_ch1.pdf&data=02%7C01%7Cted.eckert%40microsoft.com%7C848549be33cc46a789f608d670c4cbd8%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C1%7C636820387889249672&sdata=kgKdCKQyxu%2BseBaIajAgmrVdPglUneXVgnPb2lCv2y4%3D&reserved=0> (I think the EPA info has been shared on the list previously - just substitute 2 through 7 at the end of the URL to get all chapters). https://www.fire.tc.faa.gov/<https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.fire.tc.faa.gov%2F&data=02%7C01%7Cted.eckert%40microsoft.com%7C848549be33cc46a789f608d670c4cbd8%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C1%7C636820387889259671&sdata=FJz%2BmtzOZBSnYcD%2FQH%2FeYQvHr5RTubCS3jrxTNkRMGM%3D&reserved=0> https://www.fire.tc.faa.gov/pdf/05-14.pdf<https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.fire.tc.faa.gov%2Fpdf%2F05-14.pdf&data=02%7C01%7Cted.eckert%40microsoft.com%7C848549be33cc46a789f608d670c4cbd8%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C1%7C636820387889259671&sdata=xBa%2BlI6uqxwD2Nr0pctLMeoNsYhmr19nnmnv%2BZxASzc%3D&reserved=0> (2005, so not quite as recent) Cheers, Adam in Atlanta [email protected]<mailto:[email protected]> On Wed, Jan 2, 2019 at 2:31 AM John Woodgate <[email protected]<mailto:[email protected]>> wrote: It is a good paper, but the sentence: The European Union's risk assessment of TBBPA is currently ongoing and will not be completed until 2003 [9] indicates that it is not exactly up-to-date. Best wishes John Woodgate OOO-Own Opinions Only J M Woodgate and Associates www.woodjohn.uk<https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.woodjohn.uk&data=02%7C01%7Cted.eckert%40microsoft.com%7C848549be33cc46a789f608d670c4cbd8%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C1%7C636820387889269675&sdata=yH4l%2BM%2F2naEyMXS8XVztiCV4fXCRPmUXCEjPpBERvjE%3D&reserved=0> Rayleigh, Essex UK On 2019-01-02 00:16, Adam Dixon wrote: Here's a good article focused on component reliability with some discussion of how red phosphorus is produced and comparison to several alternate fire retardant chemistries: https://www.dfrsolutions.com/red-phosphorus-induced-failures-in-encapsulated-circuits<https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.dfrsolutions.com%2Fred-phosphorus-induced-failures-in-encapsulated-circuits&data=02%7C01%7Cted.eckert%40microsoft.com%7C848549be33cc46a789f608d670c4cbd8%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C1%7C636820387889279679&sdata=Q0%2FkdlheSyQcPQsezLP5E67v5rlohaMASSEySYYf%2BlU%3D&reserved=0> Cheers, Adam in Atlanta [email protected]<mailto:[email protected]> On Tue, Jan 1, 2019 at 5:46 PM John Woodgate <[email protected]<mailto:[email protected]>> wrote: Well, there wouldn't be any mention of white phosphorus, of course, because that would indicate that the technique is not safe at all. I just wonder how they stop it happening; it appears to be just a mechanical envelopment by the polyamide (e.g. Nylon). If so, prolonged moderate heating over several years might cause migration and subsequent conversion to the other allotrope at surfaces. The BASF document is quite informative: In a report by the German Federal Environment Agency, it is stated that the red phosphorus used in polymers can only be released into the environment at the plastic interfaces, where it reacts with water to form phosphorus oxides and phosphoric acids. Actually, it's a two-step process; first we get oxidation: 4P +3O2 >2P2O3, then the trioxide dissolves in water to make 'phosphorous acid' (the quotes are because it exists in two forms with different formal chemical names). I just hope that this isn't another case like CFCs, where a highly undesirable effect was not recognized until it became serious. The Wikipedia article on allotropes of phosphorus says: However, for electronic/electrical systems, red phosphorus flame retardant has been effectively banned by major OEMs due to its tendency to induce premature failures. There have been two issues over the years: the first was red phosphorus in epoxy molding compounds inducing elevated leakage current in semiconductor devices[5] and the second was acceleration of hydrolysis reactions in PBT insulating material. I think that's a wrap! Best wishes John Woodgate OOO-Own Opinions Only J M Woodgate and Associates www.woodjohn.uk<https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.woodjohn.uk&data=02%7C01%7Cted.eckert%40microsoft.com%7C848549be33cc46a789f608d670c4cbd8%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C1%7C636820387889279679&sdata=8qRjSODOABwLAnDcghjuwqZShazGi0TIqZyu1dmhzNc%3D&reserved=0> Rayleigh, Essex UK On 2019-01-01 21:24, Richard Nute wrote: If the hype is true, and my interpretation is correct, red phosphorous as a flame-retardant additive is much better than bromine-based additives. I don’t know of cost differential. (In the two websites I looked at, there was no mention of degradation to white phosphorus.) BASF: https://www.plasticsportal.net/wa/plasticsEU~en_GB/function/conversions:/publish/common/upload/technical_journals/electronics_and_mechatronics/Umwuchtsensor.pdf<https://nam06.safelinks.protection.outlook.com/?url=https:%2F%2Fwww.plasticsportal.net%2Fwa%2FplasticsEU~en_GB%2Ffunction%2Fconversions:%2Fpublish%2Fcommon%2Fupload%2Ftechnical_journals%2Felectronics_and_mechatronics%2FUmwuchtsensor.pdf&data=02%7C01%7Cted.eckert%40microsoft.com%7C848549be33cc46a789f608d670c4cbd8%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C1%7C636820387889289692&sdata=g2YULhjAJ7IKUOnfDiyOSM9LD5SnUyVxcPz%2FqN%2F6obU%3D&reserved=0> Rinka: http://www.rinka.co.jp/english/products/flame-retardant/index.html<https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.rinka.co.jp%2Fenglish%2Fproducts%2Fflame-retardant%2Findex.html&data=02%7C01%7Cted.eckert%40microsoft.com%7C848549be33cc46a789f608d670c4cbd8%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C1%7C636820387889299705&sdata=VqveV60kq1uK00nSrik66%2Bs5RBzlarUTwd6WQX7xNRo%3D&reserved=0> Best wishes for the New Year, Rich - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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