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Solder paste - Lead free?

:: EPE Chat Zone ­:: ­Radio Bygones Message Board :: » EPE Forum Archives 2010 - » Archive through 22 June, 2010 » Solder paste - Lead free? « Previous Next »

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armadillo
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Post Number: 273
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Posted on Friday, 11 June, 2010 - 11:02 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

In the July EPE there is an article on reflow soldering of SMD ICs. It refers to using Tin - Lead solder paste.
Surely these days solder paste is lead free thus requiring different temperatures? Or are both types available?

I've been out of the loop since I retired so I would be interested to know - not that my hands are steady enough these days to solder DILs let alone SMDs.

Armadillo
There's no such thing as gravity..........
The earth sucks!
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gordon
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Posted on Friday, 11 June, 2010 - 03:32 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

I haven't used the lead free solder, but tin/lead and lead free solder pastes are available.
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phonoplug
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Posted on Friday, 11 June, 2010 - 05:46 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Lead solder has been available, at times even more available than lead free, since the RoHS stuff of 2006. Some products are excempt, such as medical equipment, so they can still be manufactured with lead solder. In fact, to some extent, lead solder is making a bit of a come-back as more exemptions are made due to the long term unreliability of lead-free solder and fine pitch ICs.

Some even say that going lead free caused the reported faults Toyota have with 'sudden acceleration' in their cars.

Indeed lead free paste requires higher temperatures to reflow - upto 260 degrees, whereas lead solder paste would happily reflow with 220 degrees.
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mee
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Posted on Sunday, 13 June, 2010 - 09:50 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Hi arm. I think that the point of reflow is that you don't need to have a steady hand. Rather a lot of spare time to position the solder and flux if you have an unsteady hand.

RS still sells low melting point solder, which is a tin/lead alloy with added silver I think. It melts at 179 degrees C. I've been using it for years.

@gordon, I didn't know that there were solder pastes that contained lead. Scary when I think about the fumes I've breathed in over the years.

When I'm soldering components that I've had around for a while, I often use flux designed for use by plumbers. Modern electronics fluxes are designed so that they need little or no cleaning of the soldering residuals. Plumbing fluxes are more aggressive, i.e. more effective. If you use a plumbing flux, simply give the board a good wash and brush with white spirit (not paraffin).

According to one of my favourite mentors, good white spirit leaves almost no residue and it is one of the least likely solvents to have a negative effect on polymers.

Cheers, mee
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mikehibbett
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Post Number: 1128
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Posted on Sunday, 13 June, 2010 - 10:12 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

>Scary when I think about the fumes I've breathed in over the years.

I still find myself sometimes soldering with an iron in one hand, grippers in the other and solder in my mouth. Kids, don't try that at home :o)

To be honest, I'd be more concerned about the effects of flux gasses over the lead. Having said that, I'm a smoker so soldering is fairly low on my list of health risks.
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ant
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Posted on Sunday, 13 June, 2010 - 10:13 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Hello Mee,

While not disputing the danger there's a historic press near here that uses a Linotype machine, overhauled and operated by a retired operator. When I saw it a year or few ago it had no form of ventilation over the pan of molten lead awaiting its chance to become letters! There must have been huge numbers of these around once and I don't ever recall any headlines of lead-poisoned printers...

Regards Ant
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mee
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Post Number: 63
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Posted on Sunday, 13 June, 2010 - 10:37 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Mike, vitamin B17. Google Video. Holland and Barret if you're in the UK. If you enjoy alcohol as much as you anjoy tobacco, make sure that you don't exceed the prescribed dose.

Incidentaly, apricot seeds are used to flavour Amaretto.

@ant. My adopted granddad worked as a printer. He died from the lead that came from the printing ink he worked with, much of which of the same I used to wipe my bum on! He died so young that I never met him.
Cheers, M
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ant
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Posted on Sunday, 13 June, 2010 - 10:45 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Hello Mee,

That's interesting, apart from being sad. I wonder if it was common? I remember the lab assistant at school had to make up the ink and it was his job also to keep the inkwells topped up.

I only had to use newspaper squares from time to time but I wonder what's in the stuff that comes off (and is also breathed in from!) the Telegraph and its ilk nowadays...

G'night Ant
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mee
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Post Number: 64
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Posted on Sunday, 13 June, 2010 - 10:50 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Got it, I think. Cheers, ant...
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mikehibbett
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Posted on Monday, 14 June, 2010 - 12:03 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

@mee,

Interesting about B17, but the wiki reference cites work that included

"The authors reported that "the hazards of amygdalin therapy were evidenced in several patients by symptoms of cyanide toxicity or by blood cyanide levels approaching the lethal range"

I think I'll be better off with Alan Carr!
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mee
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Post Number: 65
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Posted on Monday, 14 June, 2010 - 10:51 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Thanks Mike. If you go on Google Video and have a look at the stories and documentaries relating to B17, you'll find a lot of conflicting evidence. From what I understand, the cyanide (and benzaldehyde) are only released when the compound meets a tumour.

Drug companies have spent a lot of time, money and effort trying to suppress thoughts on B17.

I've been regularly eating two almond pips a day for a long time. Cheers, mee
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kevinbrunt
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Posted on Monday, 14 June, 2010 - 02:00 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

@mee,

I don't believe that the printing ink contained lead - that was the "hot metal" of the printing plates. What the ink *did* contain were compounds of the element whose chemical symbol is As (and whose name is likely to get eaten by the board's Bowlderising software.)

The As was there to stop the ink coming off on the fingers.
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mee
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Post Number: 66
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Posted on Monday, 14 June, 2010 - 06:15 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Thanks Kevin. I remember now that you mention it. You're right. My mum told me that she thought it was the ink that caused caused his death and I've never really questioned what she said.

So that's what that type of software's called! It deleted my use of the another word for a cat. I was able to leave the deletion in as the word following it was "footing".

Cheers, mee

ps, I've just remembered that I did think about what she said when I was a kid, and assumed that the lead in the ink must have been the same lead that used to be used in early pencils.

I seem to remember that lead pencils worked better when you gave the point a lick. That's nothing though when you consider that lead oxide used to be used as a sweetener in cider!

(Message edited by mee on 14 June, 2010)
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armadillo
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Posted on Monday, 14 June, 2010 - 10:21 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Nearly as bad as putting a mercury amalgam into a hole in your teeth.


Armadillo
There's no such thing as gravity..........
The earth sucks!
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ant
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Posted on Monday, 14 June, 2010 - 10:34 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Hello Mee et al,

We could start a thread in "Anything else" which aimed to find and list all the words which the nanny software censors. Or perhaps ARW has access thereto?

I shall attempt to start it - should be fun finding euphemisms, too!

Regards Ant
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mee
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Post Number: 69
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Posted on Monday, 14 June, 2010 - 11:21 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Wish I had you're energy Ant. All I can say is that in my view, you're right. Good luck. I'll have a look and contribute if I can.

@armadillo, my loads of crappy tooth fillings do worry me, but they dont worry me so much as the mercury that was injected into me when I regularly crossed the road to the hospital from the factory where I worked to report an injury.

Every time I got a tetanus injection, followed by a peniccilin injection - two shots of mercury.
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mee
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Post Number: 70
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Posted on Tuesday, 15 June, 2010 - 10:49 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Oops, "your energy" sorry, it was late... There's a typo in there too.

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