31 Mar
2017
31 Mar
'17
4:32 a.m.
I'm down to the last few P112 boards for sale and am pondering another run
of them because demand is steady. One of the biggest challenges for the
last run was getting the QFP-packaged 100-pin chips[1] in a state such
that the pick-and-place robot wouldn't throw a fit about slight
differences in lead position. The stuffing house insisted that I send
them new chips. Pulls, though they looked perfectly okay to me, were not
acceptable. Does anyone here know anything about pick-and-place robots
using pulled 100-pin QFPs, particularly a stuffing house that can work
with such chips and not screw up?
[1] The now-obsolete super-io chips
--
David Griffith
dave at 661.org
A: Because it fouls the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
31 Mar
31 Mar
9:24 a.m.
On 03/31/2017 06:32 AM, David Griffith via cctalk wrote:
I'm down to the last few P112 boards for sale and am
pondering another run of them because demand is steady.
One of the biggest challenges for the last run was getting
the QFP-packaged 100-pin chips[1] in a state such that the
pick-and-place robot wouldn't throw a fit about slight
differences in lead position. The stuffing house insisted
that I send them new chips. Pulls, though they looked
perfectly okay to me, were not acceptable. Does anyone
here know anything about pick-and-place robots using
pulled 100-pin QFPs, particularly a stuffing house that
can work with such chips and not screw up?
[1] The now-obsolete super-io chips
There USED to be outfits that recycled chips. They had some
system to clean and replate/reflow the leads and align
them. The good ones could counterfeit them for new, you
absolutely could NOT TELL they were not new from the
factory. I have no idea if any of these outfits still
exist. Probably they do, in China!
My P&P would have no problem, it uses mechanical alignment
jaws. But, modern P&P use vision to locate the solder area
of the leads and then position using those coordinates. So,
anything that changes the reflection of the leads or causes
slight misalignment would cause an alignment failure.
Jon
10:51 a.m.
On 03/31/2017 06:32 AM, David Griffith via cctalk wrote:
Is this something that an experienced hand can manually do?
Of all the CP/M platforms its one of the few I haven't done. But
it keeps popping after I've long figured its long gone.
I'm not afraid of SMT as I proto using 0603 and 0402 parts
at uhf/microwave freehand.
Baving delt with layouts for BGA and large pinout devices usually getting
fiducial marks on the board so it can locate and position without
optical works.
One time the board designer messed up and we had to use existing fixed
points
for that. PITA but it worked. After that I got into the board layout
bit and DFM.
Allison
I'm down to the last few P112 boards for sale and am pondering
another run of them because demand is steady. One of the biggest
challenges for the last run was getting the QFP-packaged 100-pin
chips[1] in a state such that the pick-and-place robot wouldn't throw
a fit about slight differences in lead position. The stuffing house
insisted that I send them new chips. Pulls, though they looked
perfectly okay to me, were not acceptable. Does anyone here know
anything about pick-and-place robots using pulled 100-pin QFPs,
particularly a stuffing house that can work with such chips and not
screw up?
[1] The now-obsolete super-io chips
10:55 a.m.
On 3/31/2017 12:51 PM, allison via cctech wrote:
Is this something that an experienced hand can
manually do?
I can verify that it is indeed possible. I lay down xc95144xl-tq100s
all the time with my iron and some flux and some wick, and I get nearly
100% rates. My eyes are not what they used to be either, so a
magnifying glass and a light touch makes all the difference.
I am sure others on list are even better than I, but I recommend flux,
place the IC, and then carefully set the board aside to dry. The flux
will dry, turn into "glue" (as the alcohol evaporates), and that helps
with soldering.
Jim
1 Apr
1 Apr
8:25 a.m.
On 03/31/2017 12:55 PM, Jim Brain via cctech wrote:
On 3/31/2017 12:51 PM, allison via cctech wrote:
For chips of the 0.65
mm lead pitch, you should be able to
lay a bead of solder paste down with a syringe, and then
tack down 2 corner leads. Once that is done, you can draw
the soldering tip across the leads and solder one whole side
in about 10 seconds. A big solder short will just roll down
Is this something that an experienced hand can
manually do?
I can verify that it is indeed possible. I lay down
xc95144xl-tq100s all the time with my iron and some flux
and some wick, and I get nearly 100% rates. My eyes are
not what they used to be either, so a magnifying glass and
a light touch makes all the difference.
I am sure others on list are even better than I, but I
recommend flux, place the IC, and then carefully set the
board aside to dry. The flux will dry, turn into "glue"
(as the alcohol evaporates), and that helps with soldering. from lead to lead until it is at the end. You need the
soldering tip to be pretty hot to draw the solder along with
it. It does take some skill to know just how much solder
paste to put down -- you want very LITTLE paste for the draw
the blob along trick to work.
Jon
31 Mar
31 Mar
11 a.m.
On Mar 31, 2017, at 1:51 PM, allison via cctech
<cctech at classiccmp.org> wrote:
On 03/31/2017 06:32 AM, David Griffith via cctalk wrote:
Is this something that an experienced hand can manually do?
Yes, definitely. 100 lead PQFP is perfectly doable if the lead pitch is not insanely
small. It takes a good fine tip soldering iron (mine is a Weller with a PTS tip), fine
solder (preferably real, i.e., 63/37 non-PC solder). Liquid flux is a big help, as is a
magnifier and bright light or modest magnification microscope.
If you have to do a couple of dozen boards this gets very tedious, but for 5-ish it
isn't a big deal.
paul
I'm down to the last few P112 boards for sale and am pondering
another run of them because demand is steady. One of the biggest
challenges for the last run was getting the QFP-packaged 100-pin
chips[1] in a state such that the pick-and-place robot wouldn't throw
a fit about slight differences in lead position. The stuffing house
insisted that I send them new chips. Pulls, though they looked
perfectly okay to me, were not acceptable. Does anyone here know
anything about pick-and-place robots using pulled 100-pin QFPs,
particularly a stuffing house that can work with such chips and not
screw up?
[1] The now-obsolete super-io chips
4:28 p.m.
On 03/31/2017 02:00 PM, Paul Koning wrote:
So happens I'm fully equipped on all counts. Including the PTS tip.
However my preference
for years has been the PTA7K (WTCP60) which is 1/4" wide! Gets a few
pins done at a time... ;)
I've not gone over to the Rohs side, most of the solders are not fun to
work with though a
few have very active fluxes and solder aluminium well. So its Kester
44 in 10 and
20 mil (inch mil) diameters.
I've done more than a few AD537 and similar Blackfin CPUs with their 288
BGA package that's
a challenge to pull and replace.
Allison
On Mar 31,
2017, at 1:51 PM, allison via cctech <cctech at classiccmp.org> wrote:
On 03/31/2017 06:32 AM, David Griffith via cctalk wrote:
Yes,
definitely. 100 lead PQFP is perfectly doable if the lead pitch is not insanely small.
It takes a good fine tip soldering iron (mine is a Weller with a PTS tip), fine solder
(preferably real, i.e., 63/37 non-PC solder). Liquid flux is a big help, as is a
magnifier and bright light or modest magnification microscope.
If you have to do a couple of dozen boards this gets very tedious, but for 5-ish it
isn't a big deal.
paul
> I'm down to the last few P112 boards for
sale and am pondering
> another run of them because demand is steady. One of the biggest
> challenges for the last run was getting the QFP-packaged 100-pin
> chips[1] in a state such that the pick-and-place robot wouldn't throw
> a fit about slight differences in lead position. The stuffing house
> insisted that I send them new chips. Pulls, though they looked
> perfectly okay to me, were not acceptable. Does anyone here know
> anything about pick-and-place robots using pulled 100-pin QFPs,
> particularly a stuffing house that can work with such chips and not
> screw up?
>
> [1] The now-obsolete super-io chips
>
>
Is this something that an experienced hand can manually do?
6:15 p.m.
On 03/31/2017 06:28 PM, allison via cctech wrote:
>>
>> Is this something that an experienced hand can manually do?
> Yes, definitely. 100 lead PQFP is perfectly doable if the lead pitch is not insanely
small. It takes a good fine tip soldering iron (mine is a Weller with a PTS tip), fine
solder (preferably real, i.e., 63/37 non-PC solder). Liquid flux is a big help, as is a
magnifier and bright light or modest magnification microscope.
>
> If you have to do a couple of dozen boards this gets very tedious, but for 5-ish it
isn't a big deal.
>
>
I have a project I do from time to time using 128-lead 14mm
TQFPs with 0.4mm lead spacing.
I use a stereo zoom microscope with a home-made LED ring
light. First, I rub the pads with a pencil eraser to remove
oxidation caused by reflow temps on the rest of the board.
I put a tiny dab of solder on two pads at opposite corners.
I then place the chip in place and reflow those pads. If
the alignment is not good enough, I can "walk" the chip a
bit by reflowing one, then the other pad. Then, I apply
liquid flux to the rows of leads with a wire dipped in the flux.
And, then solder down the rows with a fine-tip soldering
iron. If a bridge develops, solder wick fixes it.
Jon
9:15 p.m.
On 03/31/2017 06:15 PM, Jon Elson via cctech wrote:
I have a project I do from time to time using 128-lead
14mm TQFPs
with 0.4mm lead spacing. I use a stereo zoom microscope with a
home-made LED ring light. First, I rub the pads with a pencil eraser
to remove oxidation caused by reflow temps on the rest of the board.
I put a tiny dab of solder on two pads at opposite corners. I then
place the chip in place and reflow those pads. If the alignment is
not good enough, I can "walk" the chip a bit by reflowing one, then
the other pad. Then, I apply liquid flux to the rows of leads with
a wire dipped in the flux. And, then solder down the rows with a
fine-tip soldering iron. If a bridge develops, solder wick fixes
it.
There are plenty of good Youtube videos describing this. I use pretty
much the same method, but start off with just a binocular loupe and then
finish with a stereo microscope for final inspection.
The soldering iron tip that works best for me is a rather broad chisel
tip. I leave the fine tips for other work.
--Chuck
1 Apr
1 Apr
8:28 a.m.
On 03/31/2017 11:15 PM, Chuck Guzis via cctech wrote:
I use pretty much the same method, but start off with
just
a binocular loupe and then finish with a stereo microscope
for final inspection.
Oh, the trick for this is there are inspection microscopes
with long working distance that allow you plenty of room to
get your hands and tools under them. Generally from about
4-6". Then, it is a breeze to solder under the microscope.
Jon
9:19 a.m.
On 04/01/2017 08:28 AM, Jon Elson wrote:
On 03/31/2017 11:15 PM, Chuck Guzis via cctech wrote:
My B&L Stereozoom allows a pretty generous space; I just don't like the
feel of doing soldering looking through two eyepieces. My 10 power
Optivisor doesn't get in the way and allows me to get the process
started easily.
As far as illumination, I find that a slightly offset light source
under the microscope is more useful than the ring light. You get a bit
of shadow with the offset source, which makes defects stand out a bit more.
BGA, on the other hand, is something that I haven't mastered--and I
doubt that I ever will, given the small size of some of the parts.
FWIW,
Chuck
I use pretty much the same method, but start off
with just a
binocular loupe and then finish with a stereo microscope for final
inspection.
Oh, the trick for this is there are inspection microscopes with long
working distance that allow you plenty of room to get your hands and
tools under them. Generally from about 4-6". Then, it is a breeze
to solder under the microscope.
10:03 a.m.
On 04/01/2017 11:19 AM, Chuck Guzis via cctalk wrote:
BGA, on the other hand, is something that I
haven't
mastered--and I doubt that I ever will, given the small
size of some of the parts.
Yes, I'm with you. if I get bad soldering on a leaded
flat-pack, I can poke the leads with an X-acto knife to find
the ones that wiggle, and then touch up the soldering and
test again. With a BGA or leadless package, there's no easy
way to detect or fix bad soldering.
Jon
7:01 a.m.
On Mar 31, 2017, at 7:28 PM, allison via cctech
<cctech at classiccmp.org> wrote:
...
I've not gone over to the Rohs side, most of the solders are not fun to
work with though a
few have very active fluxes and solder aluminium well. So its Kester
44 in 10 and
20 mil (inch mil) diameters.
Before building my most recent project (which involves an unpleasantly small-pitched TSOP
package housing multiple RS232 level converters) I asked experts at work (technicians who
do a lot of fine detail soldering) about RoHS.
The answer was very clear. If you must use that stuff because of regulations, that's
one thing. If it's for your own use and the rules aren't applicable, don't be
silly, use real solder.
paul
6:59 p.m.
On 04/01/2017 07:01 AM, Paul Koning via cctalk wrote:
Before building my most recent project (which involves an
unpleasantly small-pitched TSOP package housing multiple RS232 level
converters) I asked experts at work (technicians who do a lot of fine
detail soldering) about RoHS.
The answer was very clear. If you must use that stuff because of
regulations, that's one thing. If it's for your own use and the
rules aren't applicable, don't be silly, use real solder.
That goes for repairing things also. I owned a Volvo in the late 90s
that would develop strange electrical problems, such as the headlights
suddenly not working. The culprit was the Bosch relay modules, many of
which had small PCBs in them. Resoldering the PCBs with real solder did
the job until I sold the thing. The audio system is similarly
affected--if the audio suddenly drops out, grab the soldering iron.
I bought a coffee maker in about 2004 that quit working after a few
months. Resoldering the PCB again did the trick--I still use the thing
today.
RoHS solder is a plague, particularly in hostile environments. I've
heard that most good plumbers who work with copper pipe, hide a spool of
50-50 in the bottom of their toolboxes, just in case. (50-50 has a wide
"plastic" range and can be "tooled" to fill gaps.)
Brass musical instruments are now assembled with RoHS solder. It's not
unusual to find that the only thing holding some parts together is the
lacquer finish--the solder has long since let go.
--Chuck
2 Apr
2 Apr
7:53 a.m.
On Sat, Apr 01, 2017 at 06:59:54PM -0700, Chuck Guzis via cctalk wrote:
On 04/01/2017 07:01 AM, Paul Koning via cctalk wrote:
Read this:
https://nepp.nasa.gov/whisker/reference/tech_papers/2011-nasa-gsfc-whisker-…
Diane
--
- db at FreeBSD.org db at db.net http://www.db.net/~db
Before building my most recent project (which involves an
unpleasantly small-pitched TSOP package housing multiple RS232 level
converters) I asked experts at work (technicians who do a lot of fine
detail soldering) about RoHS.
The answer was very clear. If you must use that stuff because of
regulations, that's one thing. If it's for your own use and the
rules aren't applicable, don't be silly, use real solder.
That goes for repairing things also. I owned a Volvo in the late 90s
that would develop strange electrical problems, such as the headlights
suddenly not working. The culprit was the Bosch relay modules, many of
which had small PCBs in them. Resoldering the PCBs with real solder did
the job until I sold the thing. The audio system is similarly
affected--if the audio suddenly drops out, grab the soldering iron.
10:40 a.m.
On 04/02/2017 07:53 AM, Diane Bruce wrote:
There are problems with the site's certificate, but I was able to wget
the paper using the --no-check-certificate option.
Tin whiskers were a big deal around 2005-2012 or so, and then the
discussions suddenly dropped off. I'm not sure why.
Here's a pretty good paper from about 2011 from Maxim that discusses the
issue:
https://www.maximintegrated.com/en/app-notes/index.mvp/id/5250
It includes a bit on the danger (or lack thereof) of using lead-based
solders in electronics. Quite frankly, I wonder why the RoHS people
didn't mandate that lead flashing on roofs, lead canes in stained-glass
windows and a host of other applications weren't banned.
--Chuck
11:15 a.m.
On Sun, Apr 02, 2017 at 10:40:40AM -0700, Chuck Guzis via cctalk wrote:
On 04/02/2017 07:53 AM, Diane Bruce wrote:
There are problems with the site's certificate, but I was able to wget
the paper using the --no-check-certificate option.
I also had to work around the stupid cert. ;)
Tin whiskers were a big deal around 2005-2012 or so, and then the
discussions suddenly dropped off. I'm not sure why.
I remember the story well. All the denials from the Toyota people and
then this story about the whiskers in the controls. ugh.
Here's a pretty good paper from about 2011 from Maxim that discusses the
issue:
https://www.maximintegrated.com/en/app-notes/index.mvp/id/5250
*nod*
It includes a bit on the danger (or lack thereof) of using lead-based
solders in electronics. Quite frankly, I wonder why the RoHS people
didn't mandate that lead flashing on roofs, lead canes in stained-glass
windows and a host of other applications weren't banned.
Not to mention lead in automobile weight balancers which is apparently
banned in Europe. I guess it's because roofs, lead canes in stainless windows
aren't recycled as quickly as electronics. I dearly wish they had have
mandated proper lead recycling instead of an outright ban.
--Chuck
Diane
--
- db at FreeBSD.org db at db.net http://www.db.net/~db
5:26 a.m.
On Fri, 31 Mar 2017, Paul Koning via cctech wrote:
That's why I put this in the context of PNP robots rather than
hand-soldering. My last run of P112 boards was 150 and I'm thinking of
doing another 150 or maybe 200.
--
David Griffith
dave at 661.org
A: Because it fouls the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
On Mar 31,
2017, at 1:51 PM, allison via cctech <cctech at classiccmp.org> wrote:
On 03/31/2017 06:32 AM, David Griffith via cctalk wrote:
Is this something that an experienced
hand can manually do?
Yes, definitely. 100 lead PQFP is perfectly doable if the lead pitch is
not insanely small. It takes a good fine tip soldering iron (mine is a
Weller with a PTS tip), fine solder (preferably real, i.e., 63/37 non-PC
solder). Liquid flux is a big help, as is a magnifier and bright light
or modest magnification microscope.
If you have to do a couple of dozen boards this gets very tedious, but
for 5-ish it isn't a big deal.
I'm down to the last few P112 boards for sale and am pondering
another run of them because demand is steady. One of the biggest
challenges for the last run was getting the QFP-packaged 100-pin
chips[1] in a state such that the pick-and-place robot wouldn't throw
a fit about slight differences in lead position. The stuffing house
insisted that I send them new chips. Pulls, though they looked
perfectly okay to me, were not acceptable. Does anyone here know
anything about pick-and-place robots using pulled 100-pin QFPs,
particularly a stuffing house that can work with such chips and not
screw up?
[1] The now-obsolete super-io chips
3 Apr
3 Apr
7:16 p.m.
On 04/02/2017 07:26 AM, David Griffith via cctech wrote:
That's why I put this in the context of PNP robots rather
than hand-soldering. My last run of P112 boards was 150
and I'm thinking of doing another 150 or maybe 200.
Phew, I sure wouldn't want to hand solder 150 - 200 boards!
Been there, done that, never want to do it again!
There are machines that can do reasonable lead pitch spacing
without vision, using mechanical alignment.
My Philips CSM84 does 0.65mm lead pitch TQFPs quite well.
One other detail is lead coplanarity. The leads from the
manufacturer are formed AFTER plating to all sit on a flat
surface. If the leads have varying solder thickness after
removal, or are bent out of the seating plane by handling,
that will also affect the ability to reflow solder them
reliably.
Jon
1 Apr
1 Apr
7:41 p.m.
On Fri, Mar 31, 2017 at 11:32:08AM +0000, David Griffith via cctalk wrote:
One of the biggest challenges for the last
run was getting the QFP-packaged 100-pin chips[1] in a state such that the
pick-and-place robot wouldn't throw a fit about slight differences in lead
position. The stuffing house insisted that I send them new chips.
What an odd problem! Well I have no idea what it feels like to be a CV
system so I don't know how to make one happy, but if it were my design I'd
lean toward (1) re-design using still-available chips (and hoard the hell
out of them this time), and/or (2) hand-soldering. Everyone's jumped in
with lots of QFP soldering thoughts. Have some more:
- www.oshstencils.com is awesome.
- RoHS solder is *fine*. Maybe it wasn't in its infancy but it is now.
I don't understand all the hate. I've been using it for almost everything
for ~10 years now. Yes I have to use higher temps but that's the iron's
problem (PTA8 tip instead of PTA7 on my WTCPT, and twiddle the knobs on
the other thingies).
- I do QFPs (0.5mm and 0.4mm) using a cheap eBay binocular microscope,
Ameritronics solder paste, and a toaster oven controlled by an Arduino
with a homemade shield on it (with a MAX6675 for a K-type Sparkfun
thermocouple which I position touching the PCB somewhere, START and RESET
buttons, a header for LCD status display, and terminals for an SSR which
turns the toaster oven on/off). It's *fantastic*. Push the START button
and everything's done when you come back (it follows the usual temp profile
automatically). I often have to do some soder-wicking afterward (maybe I
should be using thinner stencils, and I always overdo it when I use a
syringe directly), but the chip stays aligned as the paste melts and the
success rate has been excellent. And solder bridges are self-fixing.
John Wilson
D Bit
9:27 p.m.
On 04/01/2017 07:41 PM, John Wilson via cctalk wrote:
- I do QFPs (0.5mm and 0.4mm) using a cheap eBay
binocular
microscope, Ameritronics solder paste, and a toaster oven controlled
by an Arduino with a homemade shield on it (with a MAX6675 for a
K-type Sparkfun thermocouple which I position touching the PCB
somewhere, START and RESET buttons, a header for LCD status display,
and terminals for an SSR which turns the toaster oven on/off). It's
*fantastic*. Push the START button and everything's done when you
come back (it follows the usual temp profile automatically). I often
have to do some soder-wicking afterward (maybe I should be using
thinner stencils, and I always overdo it when I use a syringe
directly), but the chip stays aligned as the paste melts and the
success rate has been excellent. And solder bridges are
self-fixing.
That's interesting, John. I've heard about the toaster oven thing for
several years now, but never tried it.
What do you do about boards with SMT components on *both* sides? I
can't see how it would work with a toaster oven.
--Chuck
9:51 p.m.
On 04/01/2017 11:27 PM, Chuck Guzis via cctalk wrote:
What do you do about boards with SMT components on
*both*
sides? I can't see how it would work with a toaster oven.
OK, this is going to
be long.
I do small-scale production of mostly motion control boards,
but also some nuclear instrumentation. Mostly 0603 to 0805
passives and SOIC up to 0.5mm pitch QFP chips. I use a lot
of FPGAs in 144 pin packages.
I have a Philips CSM84 pick and place machine. This is an
old-style machine, with mechanical alignment jaws for
centering and rotation, no vision, except it has a "one
pixel camera" called a beam sensor to pick up the fiducials
on the PCB. It steers the XY gantry around to map out the
fiducial spots.
I make my own solder stencils using my existing PCB fab gear
(which I almost never use for making PCBs anymore, just too
much mess.) But, a solder stencil is basically a PC board
without the glass epoxy substrate. I use .003" brass shim
stock, laminate dry film photoresist, expose, etch in ferric
chloride and, voila, a stencil. A BIG part of the trick is
to know how to reduce aperture size for specific chips. As
the lead pitch gets finer, the apertures have to get
smaller, or you end up with solder bridges.
So, after applying the solder paste with the stencil, and
then running through the pick & place machine, I put it in
the GE toaster oven. I bought the biggest toaster oven they
had at WalMart ten years ago. I got a thermocouple ramp and
soak controller and a roll of thermocouple wire on eBay.
The ramp and soak controller can follow a profile of the sort:
Start at room temp
ramp to 180 C at 30 C / minute
hold at 180 C for 1 minute
ramp to 245 C at 30 C / minute
hold at 245 C for 1 minute
ramp to original temp at 50 C / minute
One of the tricks I found out very fast was the thermocouple
doesn't absorb IR the way a board does, the first board I
did came out warped like a potato chip and nearly black. It
occurred the me to poke the thermocouple junction into a
through-hole in the board, and then it all worked. I still
have some slight problems with some areas of the oven
running a bit cooler or hotter, so I have to tweak the peak
temp setting sometimes to get all the boards soldered.
I was lucky to find really FINE thermocouple wire on eBay,
so that the junctions are small enough to fit even fairly
small through holes.
I've done well over 1000 boards with this system. Oh, and
most of it is RoHS, too.
Jon
2 Apr
2 Apr
6:37 a.m.
On Apr 2, 2017, at 12:51 AM, Jon Elson via cctalk
<cctalk at classiccmp.org> wrote:
On 04/01/2017 11:27 PM, Chuck Guzis via cctalk wrote:
I have a nice article about toaster oven SMD work. It's in German, via the PCB Pool
website if I remember right. It mentions that problem. The solution picked in that
article was to use a spare board (same or similar layout) as the thermocouple holder. But
attaching to the actual board sounds good.
paul
What do you do about boards with SMT components
on *both* sides? I can't see how it would work with a toaster oven.
OK, this is
going to be long.
I do small-scale production of mostly motion control boards, but also some nuclear
instrumentation. Mostly 0603 to 0805 passives and SOIC up to 0.5mm pitch QFP chips. I
use a lot of FPGAs in 144 pin packages.
...
One of the tricks I found out very fast was the thermocouple doesn't absorb IR the
way a board does, the first board I did came out warped like a potato chip and nearly
black. It occurred the me to poke the thermocouple junction into a through-hole in the
board, and then it all worked. I still have some slight problems with some areas of the
oven running a bit cooler or hotter, so I have to tweak the peak temp setting sometimes to
get all the boards soldered.
1:45 p.m.
On Apr 2, 2017, at 9:37 AM, Paul Koning via cctalk
<cctalk at classiccmp.org> wrote:
...
I have a nice article about toaster oven SMD work. It's in German, via the PCB Pool
website if I remember right.
Here it is: https://www.beta-estore.com/download/rk/RK-10001_76.pdf
paul
5:39 p.m.
New subject: Items available in Sacramento, CA
I got this from Daniel. You can contact him directly if there's anything
of interest.
Daniel de Long <delong at ulink.net>
I will be going there on Tuesday and could bring things back to the bay
area if they are not too large.
I will have a trailer.
Bob
___________________________________________________________________________________
Bob,
Equipment available:
1 IBM 557 Interpreter with manuals
1 MIA 557 Interpreter (IBM) with manuals
3 IBM 3178 with control and key board, $125
1 IBM 3274-90
2 IBM 3287-2 Printer
1 IBM 8513 Color Display
1 IBM 9518-001 Display
1 OTC 850 printer
1 Telex 287 Printer(IBM 3287 type)
1 Telex 8020 Model 266 Tape Drive 9 track 1600/6250 BPI with Controller,
manuals $300 including 1 Telex 8020 tape drive (new freight damage-fell
off lift gate).
1 Memorex 4303 line printer speed between 1200-1500 lines per minute
3 Control Data 9 track tape (Keystone) drives and PC controller card &
cable, $150 each
1 Control Data 9 track tape drive without controller.
1 Sun Microsystems 9 track drive (Keystone)
2 Cipher 9 track tape drive, $250 each
1 Memorex 3693 Controller with Drive
3 Memorex 3690 Drive (IBM 3370)
2 Fujitsu M2485 (IBM 3480 type) tape drive 18 Track
1 Fujitsu M2485N CA01011-B063 36 Track with auto loader
1 Fujitsu 128 Track tape drive
Thanks
Dan
--
Vintage computers and electronics
www.dvq.com
www.tekmuseum.com
www.decmuseum.org
1 Apr
1 Apr
9:58 p.m.
On 04/01/2017 11:27 PM, Chuck Guzis via cctalk wrote:
What do you do about boards with SMT components on
*both*
sides? I can't see how it would work with a toaster oven
Oh, part 2. Most of
my boards have parts on both sides. If
you have a glue dispenser, you can apply glue to your first
side part locations after solder paste but before part
placement, then print solder for 2nd side, place parts and
then reflow both sides at once. Well, I don't have a glue
dispenser, although it is an option on my P&P machine.
So, I print the solder paste on the back side (mostly
decoupling caps) place these parts and reflow, then print
solder paste for the front, place the ICs, etc. and reflow
again. I do have one board with a 5-lead TO-220 switching
regulator chip on the back side. I didn't know if it would
fall off or not, but tried it, and was amazed that I've
NEVER had one fall off when the top side was reflowed. The
solder almost certainly goes liquid again, but the surface
tension holds even this large part in place! The small
passives on the back will be held by surface tension for sure!
Jon
10:43 p.m.
On Sat, Apr 01, 2017 at 09:27:47PM -0700, Chuck Guzis via cctalk wrote:
What do you do about boards with SMT components on
*both* sides? I
can't see how it would work with a toaster oven.
I have much less experience than Jon Elson but I've tried it a few times
and my results agree with his: surface tension does the trick. I cook it
once with the solder side up and put on the decoupling caps (all I've ever
had on the flip side -- some chips need dozens and it's the only way to fit
them all), then flip it and perch the edges of the board on two pieces of
tiny aluminum tubing from a hobby store (so the center of the board won't
touch the rack in the toaster oven and nothing will disturb the caps), and
cook on the rest of the parts. Once or twice I've been desoldering and
*wanted* parts to fall off, and I had to get in there and thwack it at
the point when it's hot enough, since otherwise they're happy where they
are (that's impressive about the TO-220 but I can see it!).
John Wilson
D Bit
2591
days inactive
2595
days old
26 comments
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