Yet another bulging-capacitors replacement

[Meat Plow]

On Fri, 03 Sep 2010 12:36:34 +0100, Arfa Daily wrote:

"Mike Tomlinson" <mike@jasper.org.uk> wrote in message
news:R+UXbOA7ZIgMFwrh@jasper.org.uk...
In article <pXKfo.13668$45.9048@newsfe29.ams2>, Arfa Daily
arfa.daily@ntlworld.com> writes

I have always been sparing with compound - and I use a lot of it as I
repair many big amps for a living - but it is a fact that a very thin
translucent layer of white, is not effective enough on a standard
non-flatted device face, and heatsink contact area, whereas with AS, it
would appear that it is.

Have you tried applying the white stuff to both surfaces, then scraping
it off with the edge of a card? That will fill in any valleys on both
surfaces, and you should get a good thermal bond with the minimum of
compound.

This is the method that AS suggest using, by the way.

--
(\__/)
(='.'=)
(")_(")



Yes Mike. Prior to starting to use the AS, I have always treated both
surfaces when using white, contrary to much perceived wisdom where it is
insisted that only one surface should be coated. I believe in doing both
surfaces for the exact same reasons that you cite. I am also doing both
surfaces with AS, but very sparingly. There are always milling patterns
on the heatsink faces on these machines, which I think is a bit bad on
the part of the manufacturers anyway, given the huge thermal loads that
are produced by these chips ...

Arfa

I've never thought it necessary to coat both surfaces. If you use
sufficient paste on one it will suffice for both sides. Key word
sufficient but not overly so. I guess it's just something you develop
a knack for in knowing what is too much or not enough. This 120 watt
AMD 955 PhenomII chip in my PC runs in its normal temp range. Idles
around 43c. CPU fan runs at 2500rpm, half of 5000 at full speed automatic
control. What I'm getting at is the heatsink that comes with the chip
has a very thin coat of Arctic. And it seems to do very well being
applied to the heatsink side only.



--
Live Fast, Die Young and Leave a Pretty Corpse

 

[Jeff Liebermann]

On Fri, 3 Sep 2010 12:31:17 +0100, "Arfa Daily"
<arfa.daily@ntlworld.com> wrote:

This is something that I was talking about with a colleague just a few days
ago. I'll take a look at the links. Going back to the differential heating
issue, I've thought a bit more about it, and it seems that the greatest
source of heat is going to be the top surface of the BGA itself, which has
the bonded heat dissipation plate for interfacing with the heatsink
assembly.

Yes, but...
<http://en.wikipedia.org/wiki/Ball_grid_array>
Heat conduction
A further advantage of BGA packages over packages with discrete
leads (i.e. packages with legs) is the lower thermal resistance
between the package and the PCB. This allows heat generated by the
integrated circuit inside the package to flow more easily to the
PCB, preventing the chip from overheating.

Heat getting into the PCB is going to be two ways i.e. by
conduction through the solder balls, and by direct radiation from the
underside of the chip.

When the PCB is so close to the bottom of the BGA package, whatever
heat is produced is radiated directly to the PCB. Assuming a fairly
uniform case temperature (possibly a bad assumption) by conduction,
the radiated heat out the bottom of the BGA case has to go somewhere.
It can't accumulate or it would just continue to heat up until it
melts. So, it heats the PCB.

Neither of these are going to be particularly
efficient, and I would expect as much heat as possible to be directed
upwards into the plate, by design.

I think you'll find that unless there's a hidden insulator somewhere
in the package, the bottom case temperature will be fairly close to
the top case temperature. If it were otherwise, the case would
distort or in extreme cases, crack. I can work out the exact numbers,
using the thermal resistance, if you give me the exact case style and
dissipation in watts.

So it seems to me that the board is going
to remain relatively cool, compared to the underside of the BGA, and more to
the point, the upper side.

How much is "relatively"? Most (not all) BGA arrays have the chip
mounted on the base. For example, see Fig 2 the wire bonded example
at:
<http://www.siliconfareast.com/bga.htm>
The heat will be coming out of the base, which will be hotter than the
lid due to some thermal resistance in the case. Others have the chip
mounted on the top. These are easily identified by the epoxy blob or
metal cover on the bottom PCB side of the BGA. See:
<http://www.intel.com/assets/pdf/pkginfo/Ch_14.pdf>
<http://www.intel.com/design/packtech/packbook.htm>
for Intel's packaging handbook. Also see 14.10 section for a little
on thermal performance. There's a section on thermal package stress
at:
<http://www.intel.com/Assets/PDF/pkginfo/ch_04.pdf>
See section 4.2.1 under "Stresses generated during a thermal
excursion".

So the hotter that the BGA is allowed to run, the
greater will be the undesired thermal difference between board and chip.

True. Heat removal is not 100% efficient. Think of temperature as
the voltage across a string of resistors (thermal resistance). Crank
up the input power and each resistor has more voltage across it.
However, the ratio of the various voltages and temperatures remains
constant as long as the thermal resistances don't change. That means
that fairly small thermal resistances, such as between the heat sink
and the case, are not going to see much of a temperature change for
increase dissipation, while large thermal resistances, such as the
heat sink to the air, are going to see a large increase.

Therefore, any help to the cooling of the upper surface of the chip, should
help to reduce the temperature differential rather than exacerbate it,
shouldn't it ?

Sure. But the difference in temperature is still what's bending the
board and breaking the bonds. That's what my guess(tm) was causing
the Nvidia video chip failures in many laptops. The chip was
literally tearing itself away from the PCB because the board was
bending.

There's another problem with your analysis. If you assume that the
edges of the PCB are at room temperature, or at least at case
temperature, then the temperature gradient across the PCB will remain
fairly constant as you increase board heating. The result is just a
larger heat affected zone, and no real improvement in cooling. It
would be like putting a computah inside a plastic bag (for
waterproofing) and dumping it inside a bucket of cold water. The case
will be very cool, but the CPU will still burn up inside.

To take it to its logical conclusion, if you could remove all
heat that the chip was generating, then there would be none to heat the
board, so there would be no thermal differential, at all ??

True. If the thermal resistance between the chip and every component
of the thermal circuit path were zero, and the thermal mass of the air
were assumed to be infinite (a really bad assumption), then the chip,
heatsink, case, and air temperature would all be the same. However,
if any or all of these exhibit any thermal resistance, there will be a
temperature difference across it.



--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Jeff Liebermann]

On Fri, 03 Sep 2010 09:27:56 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

http://www.intel.com/design/packtech/packbook.htm
for Intel's packaging handbook. Also see 14.10 section for a little
on thermal performance. There's a section on thermal package stress
at:
http://www.intel.com/Assets/PDF/pkginfo/ch_04.pdf
See section 4.2.1 under "Stresses generated during a thermal
excursion".

I just noticed table 4-14 on Page 4-24 of the above handbook. It's a
table of the number of power cycles a CPU is expected to endure before
failure.

4.2.2 Temperature Cycles in Operation
A microprocessor package is subjected to numerous heating and
cooling cycles in operation. When the device is powered up, its
temperature rises, and when it is shut down, its temperature drops.
The magnitude of the maximum temperature on the die surface depends
on the thermal solution employed, and is usually between 80 to
125°C. In addition to these power on and power off cycles
(maxi-cycles), the microprocessor is cycled between different
intermediate temperature values depending upon processor usage
(mini-cycles) in any application program. The Institute for
Interconnecting and Packaging Electronic Circuits [2] lists the
typical worst case usage conditions for personal computers and
consumer electronics as given below. This table is intended only as
a guideline, and individual companies use different field use
conditions based on their research.

Category Worst case use environment
Tmin °C Tmax °C DT °C Dwell (hrs) Cycle/yr Approx. Years in Service
Consumer 0 +60 35 12 365 1-3
Computers +15 +60 20 2 1460 5

As I read this, if you turn your computer on and off once a day for 5
years, the CPU could fail due to thermal fatigue. For consumer
electronics, it's 1-3 year. Lovely...




--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Mike Tomlinson]

In article <_45go.37362$aI3.30356@newsfe05.ams2>, Arfa Daily
<arfa.daily@ntlworld.com> writes

There are always milling patterns on
the heatsink faces on these machines, which I think is a bit bad on the part
of the manufacturers anyway, given the huge thermal loads that are produced
by these chips ...

Indeed. I think they hope the thermal compound (or phase-changing pad)
will cover up a multitude of sins.

--
(\__/)
(='.'=)
(")_(")

 

[Jeff Liebermann]

On Fri, 3 Sep 2010 06:24:11 +0100, Mike Tomlinson <mike@jasper.org.uk>
wrote:

Have you tried applying the white stuff to both surfaces, then scraping
it off with the edge of a card? That will fill in any valleys on both
surfaces, and you should get a good thermal bond with the minimum of
compound.

This is the method that AS suggest using, by the way.

I've always suspected that it's a conspiracy by the manufacturer to
consume more expensive Artic Silver. Kinda like washing your hair
twice with "pH balance" shampoo.

The best heat tranfer between heat sink and CPU is metal to metal
contact, with no grease. The problem is that neither the heat sink or
CPU lid are flat and have pits, holes, gouges, lumps, cavities, and
other problems that prevent good contact. Even without these problem,
and with a mirror finish base, the typical warped package and
non-stress relieved heat sink, will not produce proper metal to metal
contact (without extreme mechanical pressure). My guess(tm) is that a
typical "brushed" aluminum heat sink to a Pentium 4 package might have
30% or less metal to metal contact. This sucks.

The idea is to fill the pits, holes, gouges, lumps, cavities, etc with
something thermally conductive, thus eliminating the need for mirror
finished and flat CPU's and heat sinks. The trick is to only fill the
pits, holes, gouges, lumps, cavities, etc and still retain as much
metal to metal contact as possible. That's not going to happen if you
use too much. As a clue, see the thermal resistance spec for Artic
Silver at:
<http://www.arcticsilver.com/as5.htm>
Thermal Resistance:
0.0045°C-in^2/Watt (0.001 inch layer)
Notice the 0.001 inch (0.025mm) layer. That's really really really
thin. So thin, that you could probably not even see it on the surface
because most of the stuff is in the pits, holes, gouges, lumps,
cavities, etc. If it had been specified with a thicker layer, the
thermal resistance would have been much worse.

It's probably a good idea to smear on some Artic Silver on both sides
of the junction, but then wipe off everything except what's in the
pits, holes, gouges, lumps, cavities, etc leaving as much metal to
metal contact as possible. If you're dealing with a badly warped or
an unpolished casting, then a little more grease might justifiable.
However, packing it on in a thick layer, but doing both sides, is a
waste.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Arfa Daily]

"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
news:gbg286hlovdiatsohrjhb9g0p92g92ocok@4ax.com...

On Fri, 3 Sep 2010 06:24:11 +0100, Mike Tomlinson <mike@jasper.org.uk
wrote:

Have you tried applying the white stuff to both surfaces, then scraping
it off with the edge of a card? That will fill in any valleys on both
surfaces, and you should get a good thermal bond with the minimum of
compound.

This is the method that AS suggest using, by the way.

I've always suspected that it's a conspiracy by the manufacturer to
consume more expensive Artic Silver. Kinda like washing your hair
twice with "pH balance" shampoo.

The best heat tranfer between heat sink and CPU is metal to metal
contact, with no grease. The problem is that neither the heat sink or
CPU lid are flat and have pits, holes, gouges, lumps, cavities, and
other problems that prevent good contact. Even without these problem,
and with a mirror finish base, the typical warped package and
non-stress relieved heat sink, will not produce proper metal to metal
contact (without extreme mechanical pressure). My guess(tm) is that a
typical "brushed" aluminum heat sink to a Pentium 4 package might have
30% or less metal to metal contact. This sucks.

The idea is to fill the pits, holes, gouges, lumps, cavities, etc with
something thermally conductive, thus eliminating the need for mirror
finished and flat CPU's and heat sinks. The trick is to only fill the
pits, holes, gouges, lumps, cavities, etc and still retain as much
metal to metal contact as possible. That's not going to happen if you
use too much. As a clue, see the thermal resistance spec for Artic
Silver at:
http://www.arcticsilver.com/as5.htm
Thermal Resistance:
0.0045°C-in^2/Watt (0.001 inch layer)
Notice the 0.001 inch (0.025mm) layer. That's really really really
thin. So thin, that you could probably not even see it on the surface
because most of the stuff is in the pits, holes, gouges, lumps,
cavities, etc. If it had been specified with a thicker layer, the
thermal resistance would have been much worse.

It's probably a good idea to smear on some Artic Silver on both sides
of the junction, but then wipe off everything except what's in the
pits, holes, gouges, lumps, cavities, etc leaving as much metal to
metal contact as possible. If you're dealing with a badly warped or
an unpolished casting, then a little more grease might justifiable.
However, packing it on in a thick layer, but doing both sides, is a
waste.

--
Jeff Liebermann jeffl@cruzio.com

All agreed

Arfa

 

[Jeff Liebermann]

On Sat, 4 Sep 2010 02:07:59 +0100, "Arfa Daily"
<arfa.daily@ntlworld.com> wrote:

All agreed
Arfa

Nobody ever agrees with me. I must have said something wrong.

See:
<http://www.microsi.com/packaging/thermal_grease.htm>
Notice what happens to the thermal resistance as the thickness of the
silicon grease layer increases. Also notice the comment about
"solvent evaporation" which is why Arctic Silver and other greases
takes a while to "break-in".


--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS

 

[Arfa Daily]

"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
news:bp7386l3k3gbikbmbrskn59sshhvn5ismm@4ax.com...

On Sat, 4 Sep 2010 02:07:59 +0100, "Arfa Daily"
arfa.daily@ntlworld.com> wrote:

All agreed
Arfa

Nobody ever agrees with me. I must have said something wrong.

See:
http://www.microsi.com/packaging/thermal_grease.htm
Notice what happens to the thermal resistance as the thickness of the
silicon grease layer increases. Also notice the comment about
"solvent evaporation" which is why Arctic Silver and other greases
takes a while to "break-in".


--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060

OK. So here's the thing. The articles that you linked to are very
interesting, and at least one says that "the pcb is the primary heatsink in
the case of BGAs". Given that is true, as it was Intel I think that said it,
is this true for all BGAs ? If it is, then what is the point of fixing an
elaborate heatsinking system to the *tops* of the BGAs, and force cooling
this with a blower of over 2 amps rating, capable of ramping up to vacuum
cleaner levels ? When it gets going a bit, it actually exhausts pretty hot
air from these things. I would say that the heatsink gets *much* hotter than
the pcb, and if you try to run the board even at idle without the heatsinks
being placed, the unit goes into thermal protect inside a few seconds. If
the pcb was really the "primary heatsink" in the case of these particular
BGAs, I would have thought that at least when just idling, they would have
run ok 'naked' ??

Arfa

 

[Jeff Liebermann]

On Sat, 4 Sep 2010 09:44:11 +0100, "Arfa Daily"
<arfa.daily@ntlworld.com> wrote:

OK. So here's the thing. The articles that you linked to are very
interesting, and at least one says that "the pcb is the primary heatsink in
the case of BGAs".

There are about 100 assorted BGA packages, most of which do not
require a heat sink. You see them on video cards, cell phones, glue
chips, game machines, and most commonly on memory cards. There is NO
WAY your large BGA package, which probably has a big FPGA burning 200
watts inside, is going to work with just heat sinking to the PCB. The
leads are the primary heat sink for the small packages, not for the
monsters.

Given that is true, as it was Intel I think that said it,
is this true for all BGAs ?

Absolutely not. Size matters.

If it is, then what is the point of fixing an
elaborate heatsinking system to the *tops* of the BGAs, and force cooling
this with a blower of over 2 amps rating, capable of ramping up to vacuum
cleaner levels ?

Desperation? If you can't get the heat out via the leads, you do
whatever else is necessary.

When it gets going a bit, it actually exhausts pretty hot
air from these things.

I think you'll be surprised at how close to meltdown your BGA's are
running. Even a small heat producer will accumulate heat if the box
isn't adequately vented. The problem is that air really sucks as a
thermal conductor. It takes an awful lot of air to do very little
cooling. Give me some numbers to work with. Incidentally, you might
try using an IR thermometer on the heat sink, BGA, and exhaust air for
a sanity check.

I would say that the heatsink gets *much* hotter than
the pcb, and if you try to run the board even at idle without the heatsinks
being placed, the unit goes into thermal protect inside a few seconds. If
the pcb was really the "primary heatsink" in the case of these particular
BGAs, I would have thought that at least when just idling, they would have
run ok 'naked' ??

Yep. For BGA's without heat sinks, the primary heat conduction path
is through the vias in the substrate, to the solder balls, and then to
the PCB. For larger BGA's, it's through the case to a heat sink.



--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Jeff Liebermann]

On Sat, 4 Sep 2010 12:28:55 -0700 (PDT), whit3rd <whit3rd@gmail.com>
wrote:

On Sep 4, 10:19 am, Jeff Liebermann <je...@cruzio.com> wrote:
On Sat, 4 Sep 2010 09:44:11 +0100, "Arfa Daily"

arfa.da...@ntlworld.com> wrote:
OK. So here's the thing. The articles that you linked to are very
interesting, and at least one says that "the pcb is the primary heatsink in
the case of BGAs".

... NO
WAY your large BGA package, which probably has a big FPGA burning 200
watts inside, is going to work with just heat sinking to the PCB.  The
leads are the primary heat sink for the small packages, not for the
monsters.

Like Intel says, it's primary.
'Primary' does not mean the heatsink with the largest heat flux. It
means the FIRST heatsink, the one that all designers start with.
BGA packages have quite a lot of thermal conductivity through those
soldered-down feet, it's not something to be ignored.
In related news, 'prime rib' is a rib roast with the rib #1 included.

<http://www.intel.com/assets/pdf/pkginfo/Ch_14.pdf>
The exact quote is:
A considerable increase in thermal effectiveness of a BGA
package can be obtained by using boards that are thermally
efficient, increasing the airflow, or providing thermal paths
from the board. Remember, with PBGAs, the board is your
primary heatsink.

PBGA is a plastic ball grid array. I guess "primary" does make sense,
since the vias going through the base are closer to the heat source
than the package lid. Therefore, heat will try to exit through the
leads before the lid.

Thermally conductive PCB material:
<http://www.bergquistcompany.com/thermal_substrates/>
<http://www.bergquistcompany.com/thermal_substrates/t-clad-product-overview.htm>

It's a wonder they don't unsolder themselves. Oh wait... Nvidia
laptop video chips do that.
<http://www.tgdaily.com/hardware-features/39045-nvidia-gpu-failures-caused-by-material-problem-sources-claim>
According to our sources, the failures are caused by a solder bump
that connects the I/O termination of the silicon chip to the pad
on the substrate. In Nvidia’s GPUs, this solder bump is created
using high-lead. A thermal mismatch between the chip and the
substrate has substantially grown in recent chip generations,
apparently leading to fatigue cracking. Add into the equation a
growing chip size (double the chip dimension, quadruple the stress
on the bump) as well as generally hotter chips and you may have the
perfect storm to take high lead beyond its limits. Apparently,
problems arise at what Nvidia claims to be "extreme temperatures"
and what we hear may be temperatures not too much above 70 degrees
Celsius.

Note the "thermal mismatch". I have a Dell XPS1210 laptop on the
bench with exactly this problem and am waiting to justify the expense
of a hot air SMT rework machine.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[whit3rd]

On Sep 4, 10:19 am, Jeff Liebermann <je...@cruzio.com> wrote:

On Sat, 4 Sep 2010 09:44:11 +0100, "Arfa Daily"

arfa.da...@ntlworld.com> wrote:
OK. So here's the thing. The articles that you linked to are very
interesting, and at least one says that "the pcb is the primary heatsink in
the case of BGAs".

... NO
WAY your large BGA package, which probably has a big FPGA burning 200
watts inside, is going to work with just heat sinking to the PCB.  The
leads are the primary heat sink for the small packages, not for the
monsters.

Like Intel says, it's primary.
'Primary' does not mean the heatsink with the largest heat flux. It
means the FIRST heatsink, the one that all designers start with.
BGA packages have quite a lot of thermal conductivity through those
soldered-down feet, it's not something to be ignored.
In related news, 'prime rib' is a rib roast with the rib #1 included.

 

[Arfa Daily]

"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
news:e09586l6jf1dgfbkg204h8ooq4qq05rjla@4ax.com...

On Sat, 4 Sep 2010 12:28:55 -0700 (PDT), whit3rd <whit3rd@gmail.com
wrote:

On Sep 4, 10:19 am, Jeff Liebermann <je...@cruzio.com> wrote:
On Sat, 4 Sep 2010 09:44:11 +0100, "Arfa Daily"

arfa.da...@ntlworld.com> wrote:
OK. So here's the thing. The articles that you linked to are very
interesting, and at least one says that "the pcb is the primary
heatsink in
the case of BGAs".

... NO
WAY your large BGA package, which probably has a big FPGA burning 200
watts inside, is going to work with just heat sinking to the PCB. The
leads are the primary heat sink for the small packages, not for the
monsters.

Like Intel says, it's primary.
'Primary' does not mean the heatsink with the largest heat flux. It
means the FIRST heatsink, the one that all designers start with.
BGA packages have quite a lot of thermal conductivity through those
soldered-down feet, it's not something to be ignored.
In related news, 'prime rib' is a rib roast with the rib #1 included.

http://www.intel.com/assets/pdf/pkginfo/Ch_14.pdf
The exact quote is:
A considerable increase in thermal effectiveness of a BGA
package can be obtained by using boards that are thermally
efficient, increasing the airflow, or providing thermal paths
from the board. Remember, with PBGAs, the board is your
primary heatsink.

PBGA is a plastic ball grid array. I guess "primary" does make sense,
since the vias going through the base are closer to the heat source
than the package lid. Therefore, heat will try to exit through the
leads before the lid.

Thermally conductive PCB material:
http://www.bergquistcompany.com/thermal_substrates/
http://www.bergquistcompany.com/thermal_substrates/t-clad-product-overview.htm

It's a wonder they don't unsolder themselves. Oh wait... Nvidia
laptop video chips do that.
http://www.tgdaily.com/hardware-features/39045-nvidia-gpu-failures-caused-by-material-problem-sources-claim
According to our sources, the failures are caused by a solder bump
that connects the I/O termination of the silicon chip to the pad
on the substrate. In Nvidia's GPUs, this solder bump is created
using high-lead. A thermal mismatch between the chip and the
substrate has substantially grown in recent chip generations,
apparently leading to fatigue cracking. Add into the equation a
growing chip size (double the chip dimension, quadruple the stress
on the bump) as well as generally hotter chips and you may have the
perfect storm to take high lead beyond its limits. Apparently,
problems arise at what Nvidia claims to be "extreme temperatures"
and what we hear may be temperatures not too much above 70 degrees
Celsius.

Note the "thermal mismatch". I have a Dell XPS1210 laptop on the
bench with exactly this problem and am waiting to justify the expense
of a hot air SMT rework machine.

--
Jeff Liebermann jeffl@cruzio.com

Assuming that you're talking a 'standard' SM rework station with hot air
pencil, and not a multi-thousand dollar fixed rework station, then the one I
recently purchased direct from China, was just 55 quid - about $85. Bit of
postage to add on of course, but at that sort of money, not too much
justification required, I would suggest ? Look on eBay for KADA 852D. Very
good value for money. I'm very pleased with mine. The eBay shop I bought
mine from (dragondirectmall I think it was), has a video on the site of them
building one, so you can get an idea of the quality.

Arfa

 

[Jeff Liebermann]

On Sun, 5 Sep 2010 01:17:10 +0100, "Arfa Daily"
<arfa.daily@ntlworld.com> wrote:

Assuming that you're talking a 'standard' SM rework station with hot air
pencil, and not a multi-thousand dollar fixed rework station, then the one I
recently purchased direct from China, was just 55 quid - about $85. Bit of
postage to add on of course, but at that sort of money, not too much
justification required, I would suggest ? Look on eBay for KADA 852D. Very
good value for money. I'm very pleased with mine. The eBay shop I bought
mine from (dragondirectmall I think it was), has a video on the site of them
building one, so you can get an idea of the quality.

<http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=370427912032>
$124. I saw your previous reply to someone asking about SMD rework
stations. The problem with the KADA 852D is that it only includes 5
generic circular nozzles (2-10mm). I need the big square BGA nozzle
assortment, which are about $100 extra from other vendors. I also
can't seem to find any listing for KADA parts. The eBay listings does
include one spare heater and soldering iron element. I've got two
off-brand soldering irons I bought at various hamfests for which I
can't find tips or repair parts. Kada looks good, but not good
enough.

What I'm looking at is, at $230.
<http://www.circuitspecialists.com/prod.itml/icOid/9766>
It's twice as expensive, but has all the features I want (or could
possibly want later). Also, lots of parts available. The tips are a
useful assortment, but I'll still need to buy some QFP nozzles at
about $18/ea. I borrowed this model for about 2 weeks and really
liked using it.

This is another possibility, as it includes 20 nozzles for $239:
<http://www.circuitspecialists.com/prod.itml/icOid/8227>
However, it leaves out the soldering iron and desoldering iron, so
it's not really a fair comparison.

What's stopping me is an impending $2,000 dental bill, which will
greatly reduce my ability to buy new toys and tools.



--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Arfa Daily]

"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
news:uis586hjidp9kgih2hv0ds91avngih0rp5@4ax.com...

On Sun, 5 Sep 2010 01:17:10 +0100, "Arfa Daily"
arfa.daily@ntlworld.com> wrote:

Assuming that you're talking a 'standard' SM rework station with hot air
pencil, and not a multi-thousand dollar fixed rework station, then the one
I
recently purchased direct from China, was just 55 quid - about $85. Bit of
postage to add on of course, but at that sort of money, not too much
justification required, I would suggest ? Look on eBay for KADA 852D. Very
good value for money. I'm very pleased with mine. The eBay shop I bought
mine from (dragondirectmall I think it was), has a video on the site of
them
building one, so you can get an idea of the quality.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=370427912032
$124. I saw your previous reply to someone asking about SMD rework
stations. The problem with the KADA 852D is that it only includes 5
generic circular nozzles (2-10mm). I need the big square BGA nozzle
assortment, which are about $100 extra from other vendors. I also
can't seem to find any listing for KADA parts. The eBay listings does
include one spare heater and soldering iron element. I've got two
off-brand soldering irons I bought at various hamfests for which I
can't find tips or repair parts. Kada looks good, but not good
enough.

What I'm looking at is, at $230.
http://www.circuitspecialists.com/prod.itml/icOid/9766
It's twice as expensive, but has all the features I want (or could
possibly want later). Also, lots of parts available. The tips are a
useful assortment, but I'll still need to buy some QFP nozzles at
about $18/ea. I borrowed this model for about 2 weeks and really
liked using it.

This is another possibility, as it includes 20 nozzles for $239:
http://www.circuitspecialists.com/prod.itml/icOid/8227
However, it leaves out the soldering iron and desoldering iron, so
it's not really a fair comparison.

What's stopping me is an impending $2,000 dental bill, which will
greatly reduce my ability to buy new toys and tools.



--
Jeff Liebermann jeffl@cruzio.com

Blimey, and I thought 200 quid was expensive for a new tooth crown ... !!

Arfa

 

[Daniel Prince]

Mike Tomlinson <mike@jasper.org.uk> wrote:

nah, standard IPA works fine. The trick is to use clean tissue wetted
with IPA, wiping just once or twice then replacing with a fresh piece,
repeating until the CPU is clean.

http://en.wikipedia.org/wiki/IPA_%28disambiguation%29

Says that IPA can mean Isopropyl alcohol. Is that what you meant?
If so, do you use 70 percent or 99 percent?
--
When a cat sits in a human's lap both the human and the cat are usually
happy. The human is happy because he thinks the cat is sitting on him/her
because it loves her/him. The cat is happy because it thinks that by sitting
on the human it is dominant over the human.

 

Talk about awakening the dead (thread) lol.

But now that you mentioned cats :

http://www.craigslist.org/about/best/col/3440629699.html