Reply by comp.zrch.embedded●November 27, 20082008-11-27
On 10 Nov, 08:04, Thorsten Trenz <n...@trenz-electronic.de> wrote:
> Hi,
>
> > free manufacture). My manufacturer tells me that this is because I
> > have a solid ground plane on the two outer layers of the PCB, =A0though
> > not underneath the solder balls on the top outer layer. They state
> > this is a large thermal mass and stopping the bga heating properly.
>
> Use another manufacturer. I suppose he uses an old infrared reflow oven.
> For this setup, you get best results with vapor phase soldering. We
> often have such setups, and it is no problem.
>
> best regards
> Thorsten Trenz
>
> --www.trenz-electronic.de
Thanks, I do not want to go down the path of removing or changing the
ground plane, expensive as it will also involve emc retesting. I was
beginning towonder whether solid ground plane on the outer layers of a
PCB was good for EMC in principle but a manufacturing problem in
practice.
Reply by Charlie Springer●November 11, 20082008-11-11
On Tue, 11 Nov 2008 06:23:53 -0800, David Brown wrote
(in article <49199583$0$25384$8404b019@news.wineasy.se>):
> Of course, lead is just one of the substances banned or limited by ROHS
> that gets into the environment like this - some of the others are worse,
> although the quantities are lower in typical pcbs.
I have plenty of mercury and silver in my teeth - maybe that is my problem. I
have plenty of mercury and silver in my teeth - maybe that is my problem, I
have plenty of mercury... probably not. The amalgam is stable and any
leaching of soluble compounds is minute and happens over 20 to 40 years.
We get lead from lead compounds in the ground. Who could be opposed to
returning it to Mother Gaia? Modern land fills in the US have clay basins and
clay caps. Someday they will be resource rich deposits of rare metals and
hydrocarbons.
Since the tin whisker problems in aerospace applications I have tried to
avoid ROHS (the labels are on practically everything now). What else of
import is restricted? Tantalum caps I would assume. I never liked their
failure modes.
I was thinking more of the new conditions under which people can solder and
such. Since I spent about 50 years with a soldering iron, I'm not crazy about
higher temp ROHS soldering and I'm not convinced of the benefits. How many
car batteries wind up in land fills?
-- Charlie Springer
Reply by David Brown●November 11, 20082008-11-11
ArarghMail811NOSPAM@NOT.AT.Arargh.com wrote:
> On Tue, 11 Nov 2008 13:16:50 +0000, JSprocket <JS@internept.org>
> wrote:
>
>> ArarghMail811NOSPAM@NOT.AT.Arargh.com wrote:
>>
>>>> It has also been
>>>> used for water pipes, and *does* cause problems - if there are corrosive
>>>> impurities in the water supply, people end up drinking lead compounds.
>>> That's why cities that still have lead water pipes have to add
>>> chemicals to the water to force a coating on the pipes, IIRC what I
>>> have read.
>> Roman lead coffins are occasionally found, e.g.
>> http://tinyurl.com/59ssmn. This one is about 16-1800 years old, and
>> hasn't dissolved yet.
>>
>> Lead in water pipes is more of a problem if the water is very soft,
>> apparently, but even then it's only a problem because all the water is
>> in constant contact with the lead, directly before it is used for
>> drinking. A few hundred pounds of solder joints in a landfill isn't
>> going to hurt anybody, though it is a wicked waste of resources.
>
> Until acidic rain dissolves it and carries it into the ground water.
> May take a few years, but it will happen.
>
> "acidic rain" = either the acid formed from sulpher emmissions from
> smoke stacks or the weak acid formed between water and CO2.
Or nitric (or is it "nitrous"?) acid formed from NO2 from car exhausts
and lightning.
Of course, lead is just one of the substances banned or limited by ROHS
that gets into the environment like this - some of the others are worse,
although the quantities are lower in typical pcbs.
Reply by ●November 11, 20082008-11-11
On Tue, 11 Nov 2008 13:16:50 +0000, JSprocket <JS@internept.org>
wrote:
>ArarghMail811NOSPAM@NOT.AT.Arargh.com wrote:
>
>>> It has also been
>>> used for water pipes, and *does* cause problems - if there are corrosive
>>> impurities in the water supply, people end up drinking lead compounds.
>> That's why cities that still have lead water pipes have to add
>> chemicals to the water to force a coating on the pipes, IIRC what I
>> have read.
>
>Roman lead coffins are occasionally found, e.g.
>http://tinyurl.com/59ssmn. This one is about 16-1800 years old, and
>hasn't dissolved yet.
>
>Lead in water pipes is more of a problem if the water is very soft,
>apparently, but even then it's only a problem because all the water is
>in constant contact with the lead, directly before it is used for
>drinking. A few hundred pounds of solder joints in a landfill isn't
>going to hurt anybody, though it is a wicked waste of resources.
Until acidic rain dissolves it and carries it into the ground water.
May take a few years, but it will happen.
"acidic rain" = either the acid formed from sulpher emmissions from
smoke stacks or the weak acid formed between water and CO2.
--
ArarghMail811 at [drop the 'http://www.' from ->] http://www.arargh.com
BCET Basic Compiler Page: http://www.arargh.com/basic/index.html
To reply by email, remove the extra stuff from the reply address.
Reply by JSprocket●November 11, 20082008-11-11
ArarghMail811NOSPAM@NOT.AT.Arargh.com wrote:
>> It has also been
>> used for water pipes, and *does* cause problems - if there are corrosive
>> impurities in the water supply, people end up drinking lead compounds.
> That's why cities that still have lead water pipes have to add
> chemicals to the water to force a coating on the pipes, IIRC what I
> have read.
Roman lead coffins are occasionally found, e.g.
http://tinyurl.com/59ssmn. This one is about 16-1800 years old, and
hasn't dissolved yet.
Lead in water pipes is more of a problem if the water is very soft,
apparently, but even then it's only a problem because all the water is
in constant contact with the lead, directly before it is used for
drinking. A few hundred pounds of solder joints in a landfill isn't
going to hurt anybody, though it is a wicked waste of resources.
JS
Reply by ●November 11, 20082008-11-11
On Tue, 11 Nov 2008 08:22:57 +0100, David Brown
<david@westcontrol.removethisbit.com> wrote:
>ArarghMail811NOSPAM@NOT.AT.Arargh.com wrote:
>> On Mon, 10 Nov 2008 13:40:13 -0000, "Peter Dickerson"
>> <first.last@REMOVEtiscali.co.uk> wrote:
>>
>>> <ArarghMail811NOSPAM@NOT.AT.Arargh.com> wrote in message
>>> news:s5ufh4dg0nqk0d9jhvurt3v1o8l06n7d4g@4ax.com...
>>>> On Mon, 10 Nov 2008 08:31:05 -0000, "Peter Dickerson"
>>>> <first.last@REMOVEtiscali.co.uk> wrote:
>>>>
>>>> <snip>
>>>>>> (Does elemental lead actually hurt anyone?)
>>>>> Yes. It affects mental development in children. Same reason it was removed
>>>> >from fuel and paint.
>>>>
>>>> uhhh, those both had lead compounds - not elemental lead
>>> Do you think elemental lead stays that way indefinitely?
>> a) No, but AFAIK, pure lead is less toxic that the removed compounds.
>> b) the original question was about 'elemental lead'.
>
>That's true as far as it goes. I suppose Peter answered the question
>that *should* have been asked, rather than the one that *was* asked - he
>probably assumed that everyone knows that potentially hazardous waste in
>landfill dumps do not stay neatly packaged in elemental form for long.
Then he probably should have qualified his answer, somewhat. :-)
>Pure lead is not toxic - but only if it stays that way.
Not real likely. :-)
>It has traditionally been used for roofing without trouble.
May get a little lead oxide in the ground. :-(
>It has also been
>used for water pipes, and *does* cause problems - if there are corrosive
>impurities in the water supply, people end up drinking lead compounds.
> On Mon, 10 Nov 2008 13:40:13 -0000, "Peter Dickerson"
> <first.last@REMOVEtiscali.co.uk> wrote:
>
>> <ArarghMail811NOSPAM@NOT.AT.Arargh.com> wrote in message
>> news:s5ufh4dg0nqk0d9jhvurt3v1o8l06n7d4g@4ax.com...
>>> On Mon, 10 Nov 2008 08:31:05 -0000, "Peter Dickerson"
>>> <first.last@REMOVEtiscali.co.uk> wrote:
>>>
>>> <snip>
>>>>> (Does elemental lead actually hurt anyone?)
>>>> Yes. It affects mental development in children. Same reason it was removed
>>> >from fuel and paint.
>>>
>>> uhhh, those both had lead compounds - not elemental lead
>> Do you think elemental lead stays that way indefinitely?
> a) No, but AFAIK, pure lead is less toxic that the removed compounds.
> b) the original question was about 'elemental lead'.
That's true as far as it goes. I suppose Peter answered the question
that *should* have been asked, rather than the one that *was* asked - he
probably assumed that everyone knows that potentially hazardous waste in
landfill dumps do not stay neatly packaged in elemental form for long.
Pure lead is not toxic - but only if it stays that way. It has
traditionally been used for roofing without trouble. It has also been
used for water pipes, and *does* cause problems - if there are corrosive
impurities in the water supply, people end up drinking lead compounds.
Reply by ●November 10, 20082008-11-10
On Mon, 10 Nov 2008 13:40:13 -0000, "Peter Dickerson"
<first.last@REMOVEtiscali.co.uk> wrote:
><ArarghMail811NOSPAM@NOT.AT.Arargh.com> wrote in message
>news:s5ufh4dg0nqk0d9jhvurt3v1o8l06n7d4g@4ax.com...
>> On Mon, 10 Nov 2008 08:31:05 -0000, "Peter Dickerson"
>> <first.last@REMOVEtiscali.co.uk> wrote:
>>
>> <snip>
>>>>
>>>> (Does elemental lead actually hurt anyone?)
>>>
>>>Yes. It affects mental development in children. Same reason it was removed
>>>from fuel and paint.
>>
>> uhhh, those both had lead compounds - not elemental lead
>
>Do you think elemental lead stays that way indefinitely?
a) No, but AFAIK, pure lead is less toxic that the removed compounds.
b) the original question was about 'elemental lead'.
--
ArarghMail811 at [drop the 'http://www.' from ->] http://www.arargh.com
BCET Basic Compiler Page: http://www.arargh.com/basic/index.html
To reply by email, remove the extra stuff from the reply address.
Reply by Bill Davy●November 10, 20082008-11-10
"nospam" <nospam@please.invalid> wrote in message
news:n6egh49bp7v25o1vebt0e84ft86g949ilk@4ax.com...
> "Peter Dickerson" <first.last@REMOVEtiscali.co.uk> wrote:
>
>>> Are you forced to use ROHS? It stinks. Safety critical and aerospace
>>> systems
>>> are exempt -- tin whiskers and all that.
>>>
>>> (Does elemental lead actually hurt anyone?)
>>
>>Yes. It affects mental development in children. Same reason it was removed
>>from fuel and paint.
>
> And how does one measure mental development of children with any accuracy?
>
> Even when you do find correlation between lead content of children and
> lack
> of mental development (which some but not all studies have found) how do
> you determine that the lead was causal and not that lack of mental
> development or more likely other factors which led to mis-measurement of
> mental development causes an increase in lead content of children?
>
>
> --
Very little point in arguing with flat-earthers, tobacco company apologists,
etc. As they do not understand epidemiology they are best left to their
happy stubborness. Still, "lead epidemiology" in Google won't persuade them
of anything (4.9M hits).
Pity Bush seemed to be the same, playing games with the planet's climate but
at least had a financial motivation.
Reply by Peter Dickerson●November 10, 20082008-11-10
"nospam" <nospam@please.invalid> wrote in message
news:n6egh49bp7v25o1vebt0e84ft86g949ilk@4ax.com...
> "Peter Dickerson" <first.last@REMOVEtiscali.co.uk> wrote:
>
>>> Are you forced to use ROHS? It stinks. Safety critical and aerospace
>>> systems
>>> are exempt -- tin whiskers and all that.
>>>
>>> (Does elemental lead actually hurt anyone?)
>>
>>Yes. It affects mental development in children. Same reason it was removed
>>from fuel and paint.
>
> And how does one measure mental development of children with any accuracy?
>
> Even when you do find correlation between lead content of children and
> lack
> of mental development (which some but not all studies have found) how do
> you determine that the lead was causal and not that lack of mental
> development or more likely other factors which led to mis-measurement of
> mental development causes an increase in lead content of children?