Sorry I missed your question, still can't find it in fact, but this
troll response caught my eye at least, so that's good.
What I mean is that leaded solder is more forgiving.
Leadfree has a higher melting point, but the maximum workable
temperature is limited by components and the PCB.
So your workable range between the minimum and maximum temperature is
much wider for leaded solder.
Also you can have much longer soldering times if you stick to a lower
temperature, again opening up the process so it will still work fine
even if you deviate from ideal parameters.
There are several other aspects in which leadfree is more troublesome,
for example the flux needs to be more aggressive, so shelf live might
suffer, but this is not universally true for all pastes.
The time you mentioned for positioning the parts is called "tack
time", after that it will dry out.
Sometimes a value called "stencil life" is given instead, which is
interchangeable for our purposes even if we might not use a stencil.
Usually this is at least three hours, plenty of time to get all the
parts done, but you should not let a half done board sit for a day.
It does pay to learn the terms, despite what some people claim,
otherwise you might not even understand the datasheets, and there is
nothing more useful than manufacturer information.
ST
On Wed, Aug 20, 2014 at 6:37 PM, Paul Alciatore
palciatore@...[Homebrew_PCBs] <
Homebrew_PCBs@yahoogroups.com> wrote:
>
>>Stefan,>Leaded paste has a higher process window than leadfree, so I
>>would recommend that.
>>
>>When you say "higher process window", do you mean that there is more
>>time to position the SMT before the solder hardens?
>
> When he says "higher process window" he means that HE is the more
> knowledgeable, "IN" person in this conversation. He understands what
> he is saying and he is using the "in" words to show this superiority.
> If you, the outsider who dares to ask for clarification, he is going
> to make you ask more questions to show your "ignorance".
>
> The truth of the matter is he is the ignorant one: ignorant of any
> knowledge of how to properly explain technical matters in a manner
> that can be easily understood.
>
> I am also an outsider here, in spite of about 50 years in the
> electronics field, and have never heard that expression before. From
> the context I believe he means it has a longer period or time for
> which it remains usable for the intended purpose; AKA: shelf life.
>
> I apologize if I seem harsh here, but I firmly believe that we need
> less "tech speak", not more of it.
>
>
>
> ------------------------------------
> Posted by: Paul Alciatore <PAlciatore@...>
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>
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