Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.forth > #13441 > unrolled thread

Phase Change Memory

Back to article view | Back to comp.lang.forth

Contents

  Phase Change Memory Jason Damisch <jasondamisch@yahoo.com> - 2012-07-02 08:39 -0700
    Re: Phase Change Memory "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-07-02 19:45 -0400
      Re: Phase Change Memory Mark Wills <markrobertwills@yahoo.co.uk> - 2012-07-03 03:29 -0700
        Re: Phase Change Memory Paul Rubin <no.email@nospam.invalid> - 2012-07-03 10:47 -0700
          Re: Phase Change Memory Bernd Paysan <bernd.paysan@gmx.de> - 2012-07-04 00:38 +0200
          Re: Phase Change Memory Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-07-04 02:06 +0000
            Re: Phase Change Memory Paul Rubin <no.email@nospam.invalid> - 2012-07-04 10:04 -0700
          Re: Phase Change Memory "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-07-04 05:05 -0400
            Re: Phase Change Memory rickman <gnuarm@gmail.com> - 2012-07-04 12:33 -0700
              Re: Phase Change Memory "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-07-04 21:48 -0400
                Re: Phase Change Memory rickman <gnuarm@gmail.com> - 2012-07-05 09:57 -0700

#13441 — Phase Change Memory

This is the first 'exotica' which I know of which is now currently available.

http://www.micron.com/products/phase-change-memory

people will think that it is too expensive to do something with, but maybe somebody here might find use for it.

fun to think that a GA144 coupled to one of these could be very low power, and have very long standby times

Jason

[toc] | [next] | [standalone]

#13457

"Jason Damisch" <jasondamisch@yahoo.com> wrote in message
news:5b646961-1ba6-44c4-b51a-cd04b923a05e@googlegroups.com...
> This is the first 'exotica' which I know of which is now currently
> available.
>
> http://www.micron.com/products/phase-change-memory
>
> people will think that it is too expensive to do something with, but
> maybe somebody here might find use for it.
>

Reading that poorly written page and a few others, I'm really not sure
just what the advantages are of PCM, if any...

> fun to think that a GA144 coupled to one of these could be very low
> power, and have very long standby times
>

Doesn't static RAM do that already (and for decades now...)?
http://en.wikipedia.org/wiki/Static_RAM

I'm unfamiliar with the GA144, but historically a microprocessor had to be
radiation hardened, i.e., for military use, in order to also have the
registers and cache be implemented as SRAM.  Generally, without SRAM, you
can't operate the microprocessor at a low clock frequencies or stop-start
execution of the microprocessor.  Low operating frequencies reduces their
power consumption.  Maybe, the PCM memory will change all that ...  Who
knows.  If PCM memory is like other phase-change materials, they may produce
excessive heat, which is needed for the phase change.  Heat is bad for
electronics, i.e., plastics melting, capacitor and semiconductor casings
failing, BGAs and power-resistors unsoldering themselves, chips and
transistors experiencing heat related failures: going "pop" and releasing
their "magic" white smoke, etc.


Rod Pemberton

[toc] | [prev] | [next] | [standalone]

#13467

On Jul 3, 12:45 am, "Rod Pemberton" <do_not_h...@notemailnot.cmm>
wrote:
> "Jason Damisch" <jasondami...@yahoo.com> wrote in message
>
> news:5b646961-1ba6-44c4-b51a-cd04b923a05e@googlegroups.com...
>
> > This is the first 'exotica' which I know of which is now currently
> > available.
>
> >http://www.micron.com/products/phase-change-memory
>
> > people will think that it is too expensive to do something with, but
> > maybe somebody here might find use for it.
>
> Reading that poorly written page and a few others, I'm really not sure
> just what the advantages are of PCM, if any...
>
> > fun to think that a GA144 coupled to one of these could be very low
> > power, and have very long standby times
>
> Doesn't static RAM do that already (and for decades now...)?http://en.wikipedia.org/wiki/Static_RAM
>
> I'm unfamiliar with the GA144, but historically a microprocessor had to be
> radiation hardened, i.e., for military use, in order to also have the
> registers and cache be implemented as SRAM.  Generally, without SRAM, you
> can't operate the microprocessor at a low clock frequencies or stop-start
> execution of the microprocessor.  Low operating frequencies reduces their
> power consumption.  Maybe, the PCM memory will change all that ...  Who
> knows.  If PCM memory is like other phase-change materials, they may produce
> excessive heat, which is needed for the phase change.  Heat is bad for
> electronics, i.e., plastics melting, capacitor and semiconductor casings
> failing, BGAs and power-resistors unsoldering themselves, chips and
> transistors experiencing heat related failures: going "pop" and releasing
> their "magic" white smoke, etc.
>
> Rod Pemberton

FRAM, anyone?

[toc] | [prev] | [next] | [standalone]

#13480

Mark Wills <markrobertwills@yahoo.co.uk> writes:
> FRAM, anyone?

FRAM is great but I get the impression that it is expensive and low
density compared to conventional ram or flash.  Its first deployment is
in those TI microcontroloers containing just 16K or so of FRAM.  This
PCM stuff is being apparently being made in devices containing 128 meg
out of the gate.

I do worry about data retention at high temperatures.  The blurb says
that the heat of soldering a chip to a circuit board erases the data.
I'd like to think heating the pins doesn't cause the actual chip die to
get all that hot.  So I worry about high ambient temperatures erasing
the data.

[toc] | [prev] | [next] | [standalone]

#13492

Paul Rubin wrote:
> FRAM is great but I get the impression that it is expensive and low
> density compared to conventional ram or flash.  Its first deployment
> is
> in those TI microcontroloers containing just 16K or so of FRAM.  This
> PCM stuff is being apparently being made in devices containing 128 meg
> out of the gate.

Megabits, that's 16MB (more than good enough for many embedded 
applications, not nearly sufficient for Android or similar).  The 
maximum SDRAM chip capacity you can get now is 4Gb, i.e. 512MB (a factor 
of 32).  However, Micron's PCM is 90nm, and the feature size of 4Gb 
SDRAMs is 25nm (factor 13 for area); I don't know how the chip size 
relates (the PCM package is pretty small) - the cell is a 4F² design 
(smaller than a DRAM cell), as the phase change material is actually 
just implemented as via and scales down nicely for higher densities (and 
it is possible to stack several layers on one chip, like n vias for 2n 
metal layers).

Well, let's see how they make progress.  They have demonstrated a 1Gb 
45nm chip on ISSCC 2010 (that would be 128 meg), but this still hasn't 
become a product yet.  That's the latest paper I found, which is from 
last year:

http://www.epcos.org/library/papers/pdf_2011/Oral-Papers/S7-01.pdf

The read performance with 266MB/s is already slower than SDRAM (though 
not really bad), but the write performance with just 9MB/s is way too 
slow to replace SDRAM.

> I do worry about data retention at high temperatures.  The blurb says
> that the heat of soldering a chip to a circuit board erases the data.
> I'd like to think heating the pins doesn't cause the actual chip die
> to get all that hot.

This is a BGA, probably with the balls going straight to the die ("chip 
scale package"), so yes, the chip actually might get that hot.  The TSOP 
should not be that sensitive.

> So I worry about high ambient temperatures erasing
> the data.

They specifiy data retention of 10 years at 70°C, comparable to Flash.  
Their highest spec'd product is -40..85°C, so not for automotive or 
military applications.

Like Ti's FRAM, this is a pilot product.  It has good density for the 
process it is made in, it's a real product, and they can learn from it.  
With currently about 100 million writes per cell, it is not good enough 
to replace SDRAM for all possible purposes, so it's more a drop-in 
replacement for NOR flash.

-- 
Bernd Paysan
"If you want it done right, you have to do it yourself"
http://bernd-paysan.de/

[toc] | [prev] | [next] | [standalone]

#13495

In article <7x7gukn3cq.fsf@ruckus.brouhaha.com>,
Paul Rubin  <no.email@nospam.invalid> wrote:
>Mark Wills <markrobertwills@yahoo.co.uk> writes:
>> FRAM, anyone?
>
>FRAM is great but I get the impression that it is expensive and low
>density compared to conventional ram or flash.  Its first deployment is
>in those TI microcontroloers containing just 16K or so of FRAM.  This
>PCM stuff is being apparently being made in devices containing 128 meg
>out of the gate.
>
>I do worry about data retention at high temperatures.  The blurb says
>that the heat of soldering a chip to a circuit board erases the data.
>I'd like to think heating the pins doesn't cause the actual chip die to
>get all that hot.  So I worry about high ambient temperatures erasing
>the data.

I worry about the idea that this is like RAM. 1,000,000 switches.
I estimate that in my 391 solution some memory places switched
some 10^9 times. I recommend euler391 : it is more of a programming
problem this time, not so mathematical (but it helps).

http://projecteuler.net/problem=391

Groetjes Albert

--
-- 
Albert van der Horst, UTRECHT,THE NETHERLANDS
Economic growth -- being exponential -- ultimately falters.
albert@spe&ar&c.xs4all.nl &=n http://home.hccnet.nl/a.w.m.van.der.horst

[toc] | [prev] | [next] | [standalone]

#13543

Albert van der Horst <albert@spenarnc.xs4all.nl> writes:
> I worry about the idea that this is like RAM. 1,000,000 switches.

I think it's supposed to be more like flash in terms of cycles.  It's
like ram in the sense that you can erase individual bits rather than
only whole sectors.

[toc] | [prev] | [next] | [standalone]

#13500

"Paul Rubin" <no.email@nospam.invalid> wrote in message
news:7x7gukn3cq.fsf@ruckus.brouhaha.com...
> [...] PCM [...]
>
> I do worry about data retention at high temperatures.

Which high temperatures: operating or manufacturing?

Bernd said it's a BGA package...  Heat is especially bad for BGAs - which
will unsolder themselves.  The chip heats up, expands or twists, applies a
stress/strain, excessive heat unsolders a "pin", it moves, disconnects from
circuit...  BGAs becoming unsoldered is the reason your XBOX 360 or
ultra-expensive high-end video card dies.

I'm not sure what the soldering temperatures are for surface mount or BGAs.
I'd assume they're somewhat less, maybe substantially less, than
through-hole since the solder doesn't have to wick into holes.  A wave
soldering machine is what solders through-hole circuits.  For a wave
soldering machine (AIR - this was some 15 to 20 years ago), the air
temperatures were 700 to 800 degrees Fahrenheit (371 to 426 degrees
Celsius), and the molten solder was 450 degF (232 degC).  *Everything* on
the board was hot enough to burn you badly.  Shields were constructed to
prevent plastics from melting.  Those temperatures were high since they
chose to switch to a bio-degradable water-based flux, instead of a solvent
based flux.  I.e., they had to drive off quite a bit of water to leave flux
on the board.  The water had to be removed before entering the "fountain" of
molten solder, or the solder would splatter leaving lead balls all over the
circuit board...

> The blurb says that the heat of soldering a chip to a circuit board erases
> the data.

That seems to indicate the phase change material has a "low" temperature for
it's phase change, at least relative to production soldering temperatures.

> I'd like to think heating the pins doesn't cause the actual chip die to
> get all that hot.

During manufacturing?   They had IC packages where the casings separated
from heat from soldering.  I.e., the top case separated from the bottom case
and exposed the die to air (died upon power-up).  That was most likely due
to the higher temperatures used in that company's process and some cheap
ICs.  More expensive ICs of the same type didn't fail that way.

Or, by hand soldering?  If a hobbyist is soldering the chip, the temperature
of the soldering iron is much lower.  However, they can still overheat it
and cause it to fail.  This happens if they solder too many pins too quickly
causing heat to buildup.  Do one or two.  Let cool.  Repeat.

> So I worry about high ambient temperatures erasing
> the data.

Once it's through manufacturing, if it's still operating and wasn't heat
damaged, it'll be operating at much "lower" temperatures from then onwards.
But, if the PCM temp is too low, or you have old heat sink grease or
insufficient heat sinking, I could see data loss as a real possibility.  If
the PCM memory is enclosed, I could see heat build up as being an issue too.
Repeated heating cycles can cause cracking or stress or strain related
failures too.

Do you remember how hot the first CD-burners made CDs by the time they were
done burning?  Sometimes, you couldn't access them later because they shrunk
so much when cooled.

This PC is the first one, of dozens, where I haven't had to change the
thermal grease for the processor after a few years because of heat failure
of the grease.


Rod Pemberton

[toc] | [prev] | [next] | [standalone]

#13554

On Jul 4, 5:05 am, "Rod Pemberton" <do_not_h...@notemailnot.cmm>
wrote:
> "Paul Rubin" <no.em...@nospam.invalid> wrote in message
>
> news:7x7gukn3cq.fsf@ruckus.brouhaha.com...
>
> > [...] PCM [...]
>
> > I do worry about data retention at high temperatures.
>
> Which high temperatures: operating or manufacturing?
>
> Bernd said it's a BGA package...  Heat is especially bad for BGAs - which
> will unsolder themselves.  The chip heats up, expands or twists, applies a
> stress/strain, excessive heat unsolders a "pin", it moves, disconnects from
> circuit...  BGAs becoming unsoldered is the reason your XBOX 360 or
> ultra-expensive high-end video card dies.
>
> I'm not sure what the soldering temperatures are for surface mount or BGAs.
> I'd assume they're somewhat less, maybe substantially less, than
> through-hole since the solder doesn't have to wick into holes.

I think surface mount soldering exposes the chips to higher temps than
wave soldering does.  Wave soldering only exposes the chips to the
temperature of the solder wave for a few seconds and only then through
the ends of the leads.  In surface mount soldering they heat the board
from the top and the chips get the full brunt of the heating.  I
believe the temperature curve heats up to something around 200°C to
220°C for as much as 30 seconds to get the full board and chips up to
that temperature before ramping up to the soldering temp which is in
the range of 250°C for some 10 to 15 seconds.  I don't know that these
temps and times are 100% accurate, but they are in the range.  You can
see that surface mount chips easily get over 200°C for a significant
time while I expect the solder wave does not raise the chip temps so
high.  But then I am not so familiar with solder wave technology.

> A wave
> soldering machine is what solders through-hole circuits.  For a wave
> soldering machine (AIR - this was some 15 to 20 years ago), the air
> temperatures were 700 to 800 degrees Fahrenheit (371 to 426 degrees
> Celsius), and the molten solder was 450 degF (232 degC).

Why would the air temps be >400°C?  What is the purpose of that?  BTW,
I assume "AIR" means "as I remember" and not air?


> *Everything* on
> the board was hot enough to burn you badly.  Shields were constructed to
> prevent plastics from melting.  Those temperatures were high since they
> chose to switch to a bio-degradable water-based flux, instead of a solvent
> based flux.  I.e., they had to drive off quite a bit of water to leave flux
> on the board.  The water had to be removed before entering the "fountain" of
> molten solder, or the solder would splatter leaving lead balls all over the
> circuit board...

But doesn't driving off the water have to be done slowly or it will
just splatter while you are drying?

Rick

[toc] | [prev] | [next] | [standalone]

#13579

"rickman" <gnuarm@gmail.com> wrote in message
news:162c7121-f3c3-4f53-8f0e-45d842f302ad@g5g2000yqg.googlegroups.com...
> On Jul 4, 5:05 am, "Rod Pemberton" <do_not_h...@notemailnot.cmm>
> wrote:
...

> > [...]
> I think surface mount soldering exposes the chips to higher temps than
> wave soldering does.  Wave soldering only exposes the chips to the
> temperature of the solder wave for a few seconds and only then through
> the ends of the leads.

Their wave soldering machine had heaters inbetween foam fluxing and wave
soldering.

AIUI, the purpose of the heaters were to heat the board to the
same temperature as the solder, to prevent splatter.  With solvent based
flux, no "extra" heat was required.  With water based flux, they had to
eliminate the water that got on the boards from the flux too.  When the
board wasn't heated enough, water based flux caused the the circuit boards
to come out wet, hot, and soft, especially if they were scored for breaking.
"Wet" boards also caused *lots* of solder splatter.

The wave soldering machine they had was comprised of a few stages.
Basically, it had a "fluxer", two stages of high temperature heaters, and a
solder pot.  A motorized chain mechanism with tungsten "teeth" or "fingers"
moved the board through the machine on an uphill incline.  (I'd guess,
maybe, 30deg.)  The fluxer was just a container that held flux and had two
foaming elements.  The elements were some type of stone machined into
cylinders.  The stone was porous.  Compressed air through the stones caused
the flux to foam and move up a flue that was placed on top of the container.
The heaters had numerous heating elements, similar to coiled heating wire in
certain toasters but encased in long glass tubes, surrounded by fiber-glass
and ceramic blocks in a steel frame, and covered by high-temp glass.  There
were two stages: one with a heater above and below.  The second had only a
single heater, IIRC, on the bottom.  That was followed by a large insulated
container (steel and ceramic blocks) that held the solder.  It also had
special high temp pumps which pumped the molten solder up a flue to create a
head or wave, or more accurately - a "waterfall", of solder.  It was about a
1/4" thick and about 2" in height above the solder pot.  The boards moved
through, got fluxed, got heated, got soldered.  Basically, the board skims
or just clips the flux and solder, if done correctly.

> In surface mount soldering they heat the board
> from the top and the chips get the full brunt of the heating.  I
> believe the temperature curve heats up to something around 200°C to
> 220°C for as much as 30 seconds to get the full board and chips up to
> that temperature before ramping up to the soldering temp which is in
> the range of 250°C for some 10 to 15 seconds.  I don't know that these
> temps and times are 100% accurate, but they are in the range.  You can
> see that surface mount chips easily get over 200°C for a significant
> time while I expect the solder wave does not raise the chip temps so
> high.  But then I am not so familiar with solder wave technology.

...

> > A wave
> > soldering machine is what solders through-hole circuits. For a wave
> > soldering machine (AIR - this was some 15 to 20 years ago), the air
> > temperatures were 700 to 800 degrees Fahrenheit (371 to 426 degrees
> > Celsius), and the molten solder was 450 degF (232 degC).
>
> Why would the air temps be >400°C?  What is the purpose of that?

Technically, it was the temperatures they set for the machine's heaters.
Since it was enclosed, the air temperature should've been similar, maybe
somewhat less.

AIUI, the temps were "high" because of the water-based flux.  The board
needed to be dry before entering the solder or they would splatter.  The
water-based flux caused some boards to become really soft.  I don't know -
but suspect - the water based flux had a high water content relative to the
flux.

> BTW, I assume "AIR" means "as I remember" and not air?

AIR "as I recall"

> > *Everything* on
> > the board was hot enough to burn you badly. Shields were constructed to
> > prevent plastics from melting. Those temperatures were high since they
> > chose to switch to a bio-degradable water-based flux, instead of a
> > solvent based flux. I.e., they had to drive off quite a bit of water to
> > leave flux on the board. The water had to be removed before entering
> > the "fountain" of molten solder, or the solder would splatter leaving
> > lead balls all over the circuit board...
>
> But doesn't driving off the water have to be done slowly or it will
> just splatter while you are drying?
>

They didn't have a drying stage.  The boards were ready to go, when using
the water based flux.  They just needed to cool after soldering.  Supposedly
(I wasn't there when they used this process but was told about it), the
solvent based flux required washing and drying the boards to remove extra
flux.  The solvent based flux was also considered hazardous.  It required a
permit for disposal.  The water based flux only required dilution with water
before entering the sewer.

Their machine foamed the flux.  Supposedly, the machine could be converted
to spraying the flux also.  From what I was told back then, that probably
would've reduced the temperatures, by applying less flux, but I don't know
for sure.

They ran the wave soldering machine at the same speed as their insertion
line.  Some products ran faster, some slower.

They also had different temperature "curves" depending on the size of board,
whether it resisted water in the flux or not, whether the board was scored
for breaking or not (weak when wet), the speed of their insertion line, etc.

It was a very old machine when I was there.  So, it's technology is probably
ancient, by now.


Rod Pemberton

[toc] | [prev] | [next] | [standalone]

#13619

On Jul 4, 9:48 pm, "Rod Pemberton" <do_not_h...@notemailnot.cmm>
wrote:
> "rickman" <gnu...@gmail.com> wrote in message
>
> news:162c7121-f3c3-4f53-8f0e-45d842f302ad@g5g2000yqg.googlegroups.com...> On Jul 4, 5:05 am, "Rod Pemberton" <do_not_h...@notemailnot.cmm>
> > wrote:
>
> ...
>
> > > [...]
> > I think surface mount soldering exposes the chips to higher temps than
> > wave soldering does.  Wave soldering only exposes the chips to the
> > temperature of the solder wave for a few seconds and only then through
> > the ends of the leads.
>
> Their wave soldering machine had heaters inbetween foam fluxing and wave
> soldering.
>
> AIUI, the purpose of the heaters were to heat the board to the
> same temperature as the solder, to prevent splatter.  With solvent based
> flux, no "extra" heat was required.  With water based flux, they had to
> eliminate the water that got on the boards from the flux too.  When the
> board wasn't heated enough, water based flux caused the the circuit boards
> to come out wet, hot, and soft, especially if they were scored for breaking.
> "Wet" boards also caused *lots* of solder splatter.
>
> The wave soldering machine they had was comprised of a few stages.
> Basically, it had a "fluxer", two stages of high temperature heaters, and a
> solder pot.  A motorized chain mechanism with tungsten "teeth" or "fingers"
> moved the board through the machine on an uphill incline.  (I'd guess,
> maybe, 30deg.)  The fluxer was just a container that held flux and had two
> foaming elements.  The elements were some type of stone machined into
> cylinders.  The stone was porous.  Compressed air through the stones caused
> the flux to foam and move up a flue that was placed on top of the container.
> The heaters had numerous heating elements, similar to coiled heating wire in
> certain toasters but encased in long glass tubes, surrounded by fiber-glass
> and ceramic blocks in a steel frame, and covered by high-temp glass.  There
> were two stages: one with a heater above and below.  The second had only a
> single heater, IIRC, on the bottom.  That was followed by a large insulated
> container (steel and ceramic blocks) that held the solder.  It also had
> special high temp pumps which pumped the molten solder up a flue to create a
> head or wave, or more accurately - a "waterfall", of solder.  It was about a
> 1/4" thick and about 2" in height above the solder pot.  The boards moved
> through, got fluxed, got heated, got soldered.  Basically, the board skims
> or just clips the flux and solder, if done correctly.
>
> > In surface mount soldering they heat the board
> > from the top and the chips get the full brunt of the heating.  I
> > believe the temperature curve heats up to something around 200°C to
> > 220°C for as much as 30 seconds to get the full board and chips up to
> > that temperature before ramping up to the soldering temp which is in
> > the range of 250°C for some 10 to 15 seconds.  I don't know that these
> > temps and times are 100% accurate, but they are in the range.  You can
> > see that surface mount chips easily get over 200°C for a significant
> > time while I expect the solder wave does not raise the chip temps so
> > high.  But then I am not so familiar with solder wave technology.
>
> ...
>
> > > A wave
> > > soldering machine is what solders through-hole circuits. For a wave
> > > soldering machine (AIR - this was some 15 to 20 years ago), the air
> > > temperatures were 700 to 800 degrees Fahrenheit (371 to 426 degrees
> > > Celsius), and the molten solder was 450 degF (232 degC).
>
> > Why would the air temps be >400°C?  What is the purpose of that?
>
> Technically, it was the temperatures they set for the machine's heaters.
> Since it was enclosed, the air temperature should've been similar, maybe
> somewhat less.
>
> AIUI, the temps were "high" because of the water-based flux.  The board
> needed to be dry before entering the solder or they would splatter.  The
> water-based flux caused some boards to become really soft.  I don't know -
> but suspect - the water based flux had a high water content relative to the
> flux.
>
> > BTW, I assume "AIR" means "as I remember" and not air?
>
> AIR "as I recall"
>
> > > *Everything* on
> > > the board was hot enough to burn you badly. Shields were constructed to
> > > prevent plastics from melting. Those temperatures were high since they
> > > chose to switch to a bio-degradable water-based flux, instead of a
> > > solvent based flux. I.e., they had to drive off quite a bit of water to
> > > leave flux on the board. The water had to be removed before entering
> > > the "fountain" of molten solder, or the solder would splatter leaving
> > > lead balls all over the circuit board...
>
> > But doesn't driving off the water have to be done slowly or it will
> > just splatter while you are drying?
>
> They didn't have a drying stage.  The boards were ready to go, when using
> the water based flux.  They just needed to cool after soldering.  Supposedly
> (I wasn't there when they used this process but was told about it), the
> solvent based flux required washing and drying the boards to remove extra
> flux.  The solvent based flux was also considered hazardous.  It required a
> permit for disposal.  The water based flux only required dilution with water
> before entering the sewer.
>
> Their machine foamed the flux.  Supposedly, the machine could be converted
> to spraying the flux also.  From what I was told back then, that probably
> would've reduced the temperatures, by applying less flux, but I don't know
> for sure.
>
> They ran the wave soldering machine at the same speed as their insertion
> line.  Some products ran faster, some slower.
>
> They also had different temperature "curves" depending on the size of board,
> whether it resisted water in the flux or not, whether the board was scored
> for breaking or not (weak when wet), the speed of their insertion line, etc.
>
> It was a very old machine when I was there.  So, it's technology is probably
> ancient, by now.
>
> Rod Pemberton


I see my misunderstanding.  When you talked about the solder
splattering I was thinking of solder paste.  But when the boards are
being dried by heating there is no solder on the board, so no
splattering.  That allows them to dry the boards very fast.

I was thinking the drying had to be at low temps or the solder paste
would splatter, but there is no solder paste, just flux.

Rick

[toc] | [prev] | [standalone]

Back to top | Article view | comp.lang.forth

csiph-web