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Comment by jaclaz | Hacker News Reader

Well, it is appropriate as a business card for an embedded systems engineers, not so much for a system security one!

More seriously, I never managed to understand the "obsession" with ROHS (this here is just an example):

>I made sure to have a lead-free process—the boards, parts, and solder paste are all RoHS—so that I wouldn't feel bad about giving them to people.

I mean, you are creating something that (besides being very nice) is not needed, that very likely will end soon in the trash (and that contains anyway a few grams of "far from clean" materials) and you worry about the tiny amount of lead in the solder tin?

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Industry wide, it's about sanitizing a highly toxic substance from the supply chain. I've met a child whose father worked with lead, and would hug him after coming home. The child ended up with permanent brain damage from ingesting traces of leaded dust on the father's clothing. In this case, it's more likely about keeping lead out of something likely to get crunched up in a parent's wallet and then shown to their child.

Lead causes permanent brain damage in children. There is no detectable amount of lead in the blood of children which is considered safe. While an adult body absorbs roughly 95% of lead into its bones, children's bodies end up storing lead in blood and soft tissue where it causes damage. When untreated, it can take months for lead to exit a child's bloodstream.

I would never consider reducing the lead used in something I've built to be wasted time.

Until what age?

Is it safe for children to solder with leaded tin? (Many people here did so as a child, I suppose)

I have no idea. I'm not a doctor, I just read a lot.

I used lead based solder as a child, and I turned out okay. That said, people used to use pewter plates and got sick from lead poisoning after eating tomatoes (the acid leached the lead from the plate); Roman soldiers would keep their wine in a lead container to sweeten it; pretty sure I've heard something about people painting their houses with leaded paint as well. On the one hand, society survived all that. On the other hand, if I have the opportunity to not risk poisoning a child by spending a couple extra dollars buying solder, that seems like a pretty easy decision to make.

I don't get this lead-free hatred on internet forums. People say they can't solder with lead-free, and that it is terrible, and that joints look dull. So much hatred that I actually tried it out. And I found the process is basically just the same and there is nothing to be afraid of. Just set the solder iron temperature a bit higher and that's it. Works like a charm.

My note was not at all about lead-free hate, actually, since several years, everyone in EU (and I believe in US as well) has been using lead-free solder (ROHS is 2003, if I recall correctly).

As you say it is just a matter of slightly increasing the soldering iron temperature, but it doesn't end there and there may be issues further on (JFYI):

https://en.wikipedia.org/wiki/Whisker_(metallurgy)

It seems like lead-free alloys tend to be more problematic in these - fortunately rare - cases.

But because it is more than 15 years that ROHS came in force, I read in 2019 "and I made it lead-free" like I would read "and I buckled my safety belt" or "I put my helmet on", etc. I see it as "the normal" way, nothing worth a mention (nowadays).

I took a quick look at a rework station in an aeronautic company in France, all leaded solder.

>I took a quick look at a rework station in an aeronautic company in France, all leaded solder.

Very possible, there are a number of (pretty much wide) exemptions even in the last version:

https://www.gov.uk/guidance/rohs-compliance-and-guidance#wha...

I've heard about whiskers, but isn't it a mostly solved problem now with low Ag alloys like SAC0307?

Bismuth is used as a replacement for lead, if you want lower temperature solder. 58Bi/42Sn alloy is cheap and about as good as Pb/Sn, but is more susceptible to thermal fatigue. I used 57Bi/42Sn/1Ag to solder heatpipes. Works great!

I think it's very considerate to not add lead to a business card people may put in their pockets.

Sure, the lead may cross one or two layers of cloth and migrate from the pocket to your skin and bite you.

More considerate would be to provide the card in a protecting sleeve (that would protect from all the bad, bad substances it may contain) or just use a good, ol' plain paper business card, posibly printed with "bioetical" ink.

>Sure, the lead may cross one or two layers of cloth and migrate from the pocket to your skin and bite you.

You get it on your hands and then ingest it when you eat. (People don't usually wash their hands after touching a business card.)

>You get it on your hands and then ingest it when you eat. (People don't usually wash their hands after touching a business card.)

I was referring to the parent poster that talked of people putting them in their pockets.

Anyway, ROHS (or lead-free) is a good thing, but it is not like you get lead poisoning (or saturnism) because of the once in your lifetime you touched sometthing contained lead and then - if you eat with your hands - you managed to ingest it:

https://en.wikipedia.org/wiki/Lead_poisoning

You need to drink from lead or lead soldered tap water or water contaminated by lead to become poisoned by lead.

In the case of the Linux business card the exposed surface that would eventually contain a minimum amount of lead - pre-ROHS soldering tin contained in the common eutectic Sn-Pb alloy 37% lead - is in the below 1 square mm range.

You would nead to actually lick hundreds or thousands of such cards to ingest any meaningful amount of lead.

And lead free soldering tin may contain (in minimal amounts):

https://en.wikipedia.org/wiki/Solder

bismuth and antimony.

I wish I could find a source on this, but when my 12mo got his routine lead test, his lead levels were elevated. It was then that I learned that even "safe" levels of lead can (it appears, inconclusively) result in long term permanent changes: reduced IQ, increased aggression.

I will forever feel guilt about letting him play in the yard as a baby (my best guess as to where it came from) and take other efforts to reduce the lead in his environment.

Depending on your life situation, it may be impractical if not impossible to reduce the lead in your environment. I am open to being further educated on this subject, but it seems like reducing lead in all products that will be handled by people is a net benefit for getting to home environments that will not cause brain damage to the infants that live in them.

> I was referring to the parent poster that talked of people putting them in their pockets.

Right, but how are you going to put it in your pocket without touching it with your hands?!

>You would nead to actually lick hundreds or thousands of such cards to ingest any meaningful amount of lead.

Lead poisoning is cumulative, so you want to avoid ingesting even very small amounts. I doubt that good data is available regarding the amount of lead that would be ingested in this scenario or its potential effects. Best to be cautious. Lead free solder is not expensive.

Lead is restricted because of what happens to it when PCBs are landfilled, not because it is harmful to touch.

Washing your hands after handling solder seems to be a fairly universal recommendation. It's not a concern for normal products because the users do not touch the bare PCB.

Lead is harmful to touch and absorb into your skin, so unless you're counting the PPMs coming off into your skin, you're wrong.

You misread. I didn't say it isn't harmful to touch. I said that isn't the reason it was restricted.

In any case it is safe to touch, despite the people downvoting me:

https://www.quora.com/How-dangerous-is-it-to-hold-a-block-of...

Avoiding leaded solder is trivial, and it is something that's hopefully handled a bunch, so why not avoid lead? I didn't know "following best practices you have to follow in your daily work anyhow" is "obsessing".

It’s actually probably harder these days to build something that isn’t RoHS compliant as a hobbyist than one that is. The vast majority of what you can buy from Digikey and Mouser and whatnot will be compliant, PCB shops will mostly do lead-free HASL (though you’d want ENIG anyway if you’re going to use a stencil), and lead-free solder pastes are more common than leaded ones. Basically you’ll probably have to either use old stock parts or pull some really old solder out of the fridge as a hobbyist to end up with lead.

Most of the Chinese board fabs will sell you prototype-quality boards for a lower price if you use a leaded HASL finish (e.g. https://jlcpcb.com/quote#/?orderType=1&stencilWidth=100&sten...)

HASL is perfectly usable with stencils, in my experience.

Were I a system security engineer, I should think I'd have a sanitized way to plug in a USB device.

How else would one do forensics?

I meant - jokingly - the opposite, i.e. you call for a consultancy a security engineer as you are interested in increasing/bettering the digital security level of your business and he produces to you the Linux USB business card, you proceed to insert it in your computer and he says:

"Ah-ha!"

Reference:

https://www.imdb.com/title/tt0094898/quotes/qt1099763

In fact, a USB condom would be a nice variant of this project for a security engineer's business card, although the female USB portion might be a bit bulky for practical use.

This is true, but given that I'm creating it, why _not_ use a lead-free process, especially given that lead is known to be very soft and toxic?

Hey you are the one that made that nice card!

Good to see you here, congratulations for your idea and creation.

I replied to that in another post, ROHS is 15 years old or more and most available parts and solders are ROHS compliant, I believe you would have had a tough time to intentionally make something that was entirely non-ROHS compliant.

I spent a month visiting a PCB factory in China. I met the people working with lead soldering.

Seriously, please choose lead-free.

Pregnant women weren't allowed to eat in the cafeteria due to the high number of miscarriages. The people inhaling the stuff all day... let's just say that had a reputation among the other factory workers for being a bit mentally challenged.

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