Soldering surface mount components

[Terry Given]

Larry Brasfield wrote:

"Clarence" <no@No.com> wrote in message
news:mTfrd.36936$6q2.19094@newssvr14.news.prodigy.com...

"Larry Brasfield" <donotspam_larry_brasfield@hotmail.com> wrote in message
news:nQcrd.395$O54.36918@news.uswest.net...

"John Larkin" <jjlarkin@highSNIPlandTHIStechPLEASEnology.com
wrote in message news:a7lpq05v0jvt6vqbg354pm22iubjgkma8j@4ax.com...

Surface-mount parts are designed to be soldered in a reflow oven,
where the entire loaded board gets heated above solder-melt
temperature for a minute or so. Most parts don't mind. I just solder
them by hand, and it pretty much always works.

Hand soldering can be very hard on SMD ceramic capacitors.
The high temperature gradiant created by applying heat suddenly
at one end can fracture the ceramic. This can lead to excess noise
or a tendency to break down at a lower than rated voltage as
moisure gets into the crack(s). The insidious aspect of this kind
of damage is that it can show up in the field, quite some time
after the parts perform alright in initial testing.

At Siemens Ultrasound, we learned this the hard way, then had it
confirmed by at least one vendor's examination of abused parts.

--Larry Brasfield

Of course this may have actually happened,


Yes, of course.


and Boy, you had some pretty lousy assembly people.


They were quite skilled and competent, generally. If you knew
the circumstances under which the hand soldering occured, you
might not be so willing to denigrate them. (But who knows?)

its the rate-of-change of temperature thats the real killer. Larger caps
are worse, as the resulting dimensional changes are bigger.

I've seen the pre-prod units used for test assembled and
soldered by hand and subjected to extensive testing. Never saw a solder
related failure of a component.


To see the excess noise phenomenon, you would have to be
looking at a circuit handling low level signals which would be
affected by random parametric shifts. To see the drop in
voltage withstand, you would have to be using parts at an
appreciable fraction of their rated voltage, or subject them
to conditions under which moisture would enter the cracks.
So the fact that you never saw that is not much reassurance.


We tested for very long periods on many boards.


But what were you testing for? Did the environment
promote moisture ingression into the cracks? Was there
thermal cycling? I must say, your failure to see that
phenomenon is weak evidence against its reality.

ROTFLMAO!

Of course we also inspected the boards before applying power and
checking for damage. Rarely had to retouch a board after the first three.


The damage I mentioned is nearly impossible to see without
a microscope. Typically, the micro-cracks do not extend
clear thru the part, and they tend to be closed, being held
together by the unbroken material. I doubt your inspection
would have caught that damage.

doesnt everyone have a binocular microscope? how quaint.

The facts I have related regarding the failure mechansim,
and the strong disrecommendation against hand soldering
ceramic SMD capacitors, came to me directly from a well
known and reputable supplier of such parts. You, or other
"we got away with something, so it must be fine" kind of
folks can disregard it and often not pay the price. Those
who desire reliability will more likely heed it.

There are also mechanical resonance related with the larger ceramic smt
parts (Marcon have poublished several papers on this effect).

Recently I have hand-soldered about 2000 0603 caps (prototypes). Perhaps
2-3 caps failed immediately; as its a prorotype I dont care about
medium-long term reliability, but no way would I give it to a customer

Cheers
Terry

 

[Clarence]

"Terry Given" <my_name@ieee.org> wrote in message
news:QEord.20625$9A.337314@news.xtra.co.nz...

Larry Brasfield wrote:
"Clarence" <no@No.com> wrote in message
news:mTfrd.36936$6q2.19094@newssvr14.news.prodigy.com...

"Larry Brasfield" <donotspam_larry_brasfield@hotmail.com> wrote in message
news:nQcrd.395$O54.36918@news.uswest.net...

"John Larkin" <jjlarkin@highSNIPlandTHIStechPLEASEnology.com
wrote in message news:a7lpq05v0jvt6vqbg354pm22iubjgkma8j@4ax.com...

Surface-mount parts are designed to be soldered in a reflow oven,
where the entire loaded board gets heated above solder-melt
temperature for a minute or so. Most parts don't mind. I just solder
them by hand, and it pretty much always works.

Hand soldering can be very hard on SMD ceramic capacitors.
The high temperature gradiant created by applying heat suddenly
at one end can fracture the ceramic. This can lead to excess noise
or a tendency to break down at a lower than rated voltage as
moisure gets into the crack(s). The insidious aspect of this kind
of damage is that it can show up in the field, quite some time
after the parts perform alright in initial testing.

At Siemens Ultrasound, we learned this the hard way, then had it
confirmed by at least one vendor's examination of abused parts.

--Larry Brasfield

Of course this may have actually happened,

Yes, of course.

and Boy, you had some pretty lousy assembly people.

They were quite skilled and competent, generally. If you knew
the circumstances under which the hand soldering occurred, you
might not be so willing to denigrate them. (But who knows?)

its the rate-of-change of temperature that's the real killer. Larger caps
are worse, as the resulting dimensional changes are bigger.

I've seen the pre-prod units used for test assembled and
soldered by hand and subjected to extensive testing. Never saw a solder
related failure of a component.

To see the excess noise phenomenon, you would have to be
looking at a circuit handling low level signals which would be
affected by random parametric shifts. To see the drop in
voltage withstand, you would have to be using parts at an
appreciable fraction of their rated voltage, or subject them
to conditions under which moisture would enter the cracks.
So the fact that you never saw that is not much reassurance.

We tested for very long periods on many boards.

But what were you testing for? Did the environment
promote moisture ingression into the cracks? Was there
thermal cycling? I must say, your failure to see that
phenomenon is weak evidence against its reality.

ROTFLMAO!

Not much moisture in a near vacuum!

Of course we also inspected the boards before applying power and
checking for damage. Rarely had to retouch a board after the first three.

The damage I mentioned is nearly impossible to see without
a microscope. Typically, the micro-cracks do not extend
clear thru the part, and they tend to be closed, being held
together by the unbroken material. I doubt your inspection
would have caught that damage.

doesn't everyone have a binocular microscope? how quaint.


The facts I have related regarding the failure mechanism,
and the strong disrecommendation against hand soldering
ceramic SMD capacitors, came to me directly from a well
known and reputable supplier of such parts. You, or other
"we got away with something, so it must be fine" kind of
folks can disregard it and often not pay the price. Those
who desire reliability will more likely heed it.

I'll take the 'disrecommendation' with a box of salt!

There are also mechanical resonance related with the larger ceramic SMT
parts (Marcon have published several papers on this effect).

Recently I have hand-soldered about 2000 0603 caps (prototypes). Perhaps
2-3 caps failed immediately; as its a prototype I don't care about
medium-long term reliability, but no way would I give it to a customer

Cheers
Terry

I am delighted to hear you wouldn't give your work to a customer. Many
prototypes are unsuited for the customer to see anyway due to the rework and
handling in engineering test. I NEVER ship a 'prototype' to anyone. That is
what a "first Article" is for!

As for the work I cited! These were weather Satellite boards, RF, motor
control, CPU, and digital communications, plus low level analog video, with
analog to digital conversion. There will only be 18 final units built, and
testing (with temperature cycling from -40 to + 80 Degrees C four times a day
at 5 degrees C per minute) was eight times a day, total time of a complete test
was 2,000 hours. MTTF predicted is 18 years. Also they must survive 50,000
Kilorads exposure.

Yes, Inspection under a microscope, 20 and 50 diameters magnification. Before
and after tests. Yes All boards were also tested on a shake table, they must
survive launch.

The Customer is NASA, they are very particular, and will launch the first of
these in 2006.

Shooting one's mouth off when someone tries to help causes a loss of
credibility!
Since your really an amateur, live with your poor workmanship and cry about it!

 

[Jim Adney]

On Tue, 30 Nov 2004 19:34:00 GMT "Steven McGahey"
<steven.doesntneedthis.mcgahey@virgin.theISP.net (remove the obvious
bits)> wrote:

I would have thought that when working with these components, you would have
to use a different approach, and try to keep the component cool (as it'll
fry otherwise), but this thread seems to suggest otherwise.

I was on the Vishay web site recently and came across a writeup they
have on hand soldering surface mount electrolytics. If you do any of
this I believe it's worth looking up. They are rather cautious and
suggest that if you spend more than 3 seconds on a junction that's too
long and you should start over with a new part.

Seems extreme to me, but they're the ones who are actually in a
position to know.

-
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------

 

[Terry Given]

Hi Clarence,

Clarence wrote:

"Terry Given" <my_name@ieee.org> wrote in message
news:QEord.20625$9A.337314@news.xtra.co.nz...

Larry Brasfield wrote:

"Clarence" <no@No.com> wrote in message
news:mTfrd.36936$6q2.19094@newssvr14.news.prodigy.com...


"Larry Brasfield" <donotspam_larry_brasfield@hotmail.com> wrote in message
news:nQcrd.395$O54.36918@news.uswest.net...


"John Larkin" <jjlarkin@highSNIPlandTHIStechPLEASEnology.com
wrote in message news:a7lpq05v0jvt6vqbg354pm22iubjgkma8j@4ax.com...


Surface-mount parts are designed to be soldered in a reflow oven,
where the entire loaded board gets heated above solder-melt
temperature for a minute or so. Most parts don't mind. I just solder
them by hand, and it pretty much always works.

Hand soldering can be very hard on SMD ceramic capacitors.
The high temperature gradiant created by applying heat suddenly
at one end can fracture the ceramic. This can lead to excess noise
or a tendency to break down at a lower than rated voltage as
moisure gets into the crack(s). The insidious aspect of this kind
of damage is that it can show up in the field, quite some time
after the parts perform alright in initial testing.

At Siemens Ultrasound, we learned this the hard way, then had it
confirmed by at least one vendor's examination of abused parts.

--Larry Brasfield

Of course this may have actually happened,

Yes, of course.


and Boy, you had some pretty lousy assembly people.

They were quite skilled and competent, generally. If you knew
the circumstances under which the hand soldering occurred, you
might not be so willing to denigrate them. (But who knows?)

its the rate-of-change of temperature that's the real killer. Larger caps
are worse, as the resulting dimensional changes are bigger.

I've seen the pre-prod units used for test assembled and
soldered by hand and subjected to extensive testing. Never saw a solder
related failure of a component.

To see the excess noise phenomenon, you would have to be
looking at a circuit handling low level signals which would be
affected by random parametric shifts. To see the drop in
voltage withstand, you would have to be using parts at an
appreciable fraction of their rated voltage, or subject them
to conditions under which moisture would enter the cracks.
So the fact that you never saw that is not much reassurance.


We tested for very long periods on many boards.

But what were you testing for? Did the environment
promote moisture ingression into the cracks? Was there
thermal cycling? I must say, your failure to see that
phenomenon is weak evidence against its reality.


ROTFLMAO!


Not much moisture in a near vacuum!


Of course we also inspected the boards before applying power and
checking for damage. Rarely had to retouch a board after the first three.

The damage I mentioned is nearly impossible to see without
a microscope. Typically, the micro-cracks do not extend
clear thru the part, and they tend to be closed, being held
together by the unbroken material. I doubt your inspection
would have caught that damage.

doesn't everyone have a binocular microscope? how quaint.


The facts I have related regarding the failure mechanism,
and the strong disrecommendation against hand soldering
ceramic SMD capacitors, came to me directly from a well
known and reputable supplier of such parts. You, or other
"we got away with something, so it must be fine" kind of
folks can disregard it and often not pay the price. Those
who desire reliability will more likely heed it.


I'll take the 'disrecommendation' with a box of salt!


There are also mechanical resonance related with the larger ceramic SMT
parts (Marcon have published several papers on this effect).

Recently I have hand-soldered about 2000 0603 caps (prototypes). Perhaps
2-3 caps failed immediately; as its a prototype I don't care about
medium-long term reliability, but no way would I give it to a customer

Cheers
Terry


I am delighted to hear you wouldn't give your work to a customer. Many
prototypes are unsuited for the customer to see anyway due to the rework and
handling in engineering test. I NEVER ship a 'prototype' to anyone. That is
what a "first Article" is for!

Hear Hear!

Reflow machines are best suited to soldering smt. If you have to do it
by hand, use hot air. A bloody great soldering is the worst way.

As for the work I cited! These were weather Satellite boards, RF, motor
control, CPU, and digital communications, plus low level analog video, with
analog to digital conversion. There will only be 18 final units built, and
testing (with temperature cycling from -40 to + 80 Degrees C four times a day
at 5 degrees C per minute) was eight times a day, total time of a complete test
was 2,000 hours. MTTF predicted is 18 years. Also they must survive 50,000
Kilorads exposure.

ouch.

Yes, Inspection under a microscope, 20 and 50 diameters magnification. Before
and after tests. Yes All boards were also tested on a shake table, they must
survive launch.

The Customer is NASA, they are very particular, and will launch the first of
these in 2006.

Shooting one's mouth off when someone tries to help causes a loss of
credibility!
Since your really an amateur, live with your poor workmanship and cry about it!

What makes you think I'm an amateur? I just dont want to hire a tech
(labour laws become a real pain in the ass when you have staff).

Cheers
Terry

 

[Clarence]

"Terry Given" <my_name@ieee.org> wrote in message
news:1yxrd.21491$9A.342817@news.xtra.co.nz...

Hi Clarence,
Clarence wrote:
"Terry Given" <my_name@ieee.org> wrote in message
news:QEord.20625$9A.337314@news.xtra.co.nz...
Larry Brasfield wrote:
"Clarence" <no@No.com> wrote in message
news:mTfrd.36936$6q2.19094@newssvr14.news.prodigy.com...

<snip>

I am delighted to hear you wouldn't give your work to a customer. Many
prototypes are unsuited for the customer to see anyway due to the rework
and
handling in engineering test. I NEVER ship a 'prototype' to anyone. That
is
what a "first Article" is for!

Hear Hear!

Reflow machines are best suited to soldering smt. If you have to do it
by hand, use hot air. A bloody great soldering is the worst way.

Since that is what they were designed for, and that is what I use them for when
it is appropriate.

As for the work I cited! These were weather Satellite boards, RF, motor
control, CPU, and digital communications, plus low level analog video, with
analog to digital conversion. There will only be 18 final units built, and
testing (with temperature cycling from -40 to + 80 Degrees C four times a
day
at 5 degrees C per minute) was eight times a day, total time of a complete
test
was 2,000 hours. MTTF predicted is 18 years. Also they must survive 50
(Op's)
Kilorads exposure.

ouch.

Yes, Inspection under a microscope, 20 and 50 diameters magnification.
Before
and after tests. Yes All boards were also tested on a shake table, they
must
survive launch.

The Customer is NASA, they are very particular, and will launch the first
of
these in 2006.

By the way, all these boards MAY be hand soldered in the limited production.
There are components which can be reliably flow soldered, but these boards are
populated on both sides, and depending upon weight MAY not remain in place
going through the reflow process with an already soldered side down. Ordinary
FR4 will usually work this way, but the aluminum cored boards get too hot on
the bottom when the core conducts the heat through the board. (There is no
"convection cooling" in space. Only radiation and conduction.)

Shooting one's mouth off when someone tries to help causes a loss of
credibility!
Since your really an amateur, live with your poor workmanship and cry about
it!

What makes you think I'm an amateur? I just don't want to hire a tech
(labor laws become a real pain in the ass when you have staff).
Cheers
Terry

Your statements were a strong clue, then the lack of experience added fuel. I
would hope I was wrong! I only maintain five consultants (1099) on call, all
specialists! I do the initial design, and work along side of experienced
specialists for a quality result.

Sometimes I take my entire team into a customers facility, it helps to have
people with all those training certifications and credentials.

Thanks for the warning about Macon. I'll avoid them!

 

[Howard Long]

I'll give this a go with the blutack (we had the same thing in Australia -
wonder what the UK equivalent is...) and desoldering braid.

It's the tiniest piece of blutak - too much and the chip's leads don't rest
in contact with the PCB solder pads. This allows you to position the chip
accurately by sight over the solder pads. The blutak then remains there ad
infinitum (or until you have to rework the chip!).

In the US blutak's like this
http://www.staples.com/Catalog/Browse/sku.asp?PageType=1&Sku=334690&bcFlag=True&bcSCatId=1&bcSCatName=Office+Supplies&bcCatId=28&bcCatName=Tape%2C+Glue+%26+Adhesives&bcClassId=10000&bcClassName=Glue+%26+Adhesive+Products

I think I also need a smaller soldering iron tip - the last one was still
too big and bulky with a 1 or 2 mm point.

Here's the iron I use
http://www.maplin.co.uk/Module.aspx?ModuleNo=10271&TabID=1&source=15&WorldID=9&doy=2m12

I use the same sized tip that was supplied with the iron - it's pointy but
not miniscule.

Cheers, Howard

 

[Watson A.Name - \"Watt Su]

"Howard Long" <howard@howardlongxxx.com> wrote in message
news:comr7t$441$1@sparta.btinternet.com...
[snip]

I think I also need a smaller soldering iron tip - the last one was
still
too big and bulky with a 1 or 2 mm point.

Here's the iron I use

http://www.maplin.co.uk/Module.aspx?ModuleNo=10271&TabID=1&source=15&Wor

ldID=9&doy=2m12

I read the text in that ad three times, and I still couldn't find
anything that said what the wattage was. Why would they leave out
someething so important?

I use the same sized tip that was supplied with the iron - it's pointy
but
not miniscule.

Cheers, Howard

 

[Terry Given]

Clarence wrote:

"Terry Given" <my_name@ieee.org> wrote in message
news:1yxrd.21491$9A.342817@news.xtra.co.nz...

Hi Clarence,
Clarence wrote:

"Terry Given" <my_name@ieee.org> wrote in message
news:QEord.20625$9A.337314@news.xtra.co.nz...

Larry Brasfield wrote:

"Clarence" <no@No.com> wrote in message
news:mTfrd.36936$6q2.19094@newssvr14.news.prodigy.com...


snip

I am delighted to hear you wouldn't give your work to a customer. Many
prototypes are unsuited for the customer to see anyway due to the rework

and

handling in engineering test. I NEVER ship a 'prototype' to anyone. That

is

what a "first Article" is for!

Hear Hear!

Reflow machines are best suited to soldering smt. If you have to do it
by hand, use hot air. A bloody great soldering is the worst way.


Since that is what they were designed for, and that is what I use them for when
it is appropriate.


As for the work I cited! These were weather Satellite boards, RF, motor
control, CPU, and digital communications, plus low level analog video, with
analog to digital conversion. There will only be 18 final units built, and
testing (with temperature cycling from -40 to + 80 Degrees C four times a

day

at 5 degrees C per minute) was eight times a day, total time of a complete

test

was 2,000 hours. MTTF predicted is 18 years. Also they must survive 50

(Op's)

Kilorads exposure.

ouch.


Yes, Inspection under a microscope, 20 and 50 diameters magnification.

Before

and after tests. Yes All boards were also tested on a shake table, they

must

survive launch.

The Customer is NASA, they are very particular, and will launch the first

of

these in 2006.


By the way, all these boards MAY be hand soldered in the limited production.
There are components which can be reliably flow soldered, but these boards are
populated on both sides, and depending upon weight MAY not remain in place
going through the reflow process with an already soldered side down. Ordinary
FR4 will usually work this way, but the aluminum cored boards get too hot on
the bottom when the core conducts the heat through the board. (There is no
"convection cooling" in space. Only radiation and conduction.)


Shooting one's mouth off when someone tries to help causes a loss of
credibility!
Since your really an amateur, live with your poor workmanship and cry about

it!

What makes you think I'm an amateur? I just don't want to hire a tech
(labor laws become a real pain in the ass when you have staff).
Cheers
Terry


Your statements were a strong clue, then the lack of experience added fuel. I
would hope I was wrong! I only maintain five consultants (1099) on call, all
specialists! I do the initial design, and work along side of experienced
specialists for a quality result.

Sometimes I take my entire team into a customers facility, it helps to have
people with all those training certifications and credentials.

Thanks for the warning about Macon. I'll avoid them!

Actually its not Marcon per se, its just that the larger ceramic caps
have mechanical resonances that can be excited electrically. square-loop
ferrite has the same problem - witness the warnings in the Ferroxcube
databook.

Cheers
Terry

 

[John Fields]

On Thu, 02 Dec 2004 23:06:21 GMT, "Clarence" <no@No.com> wrote:

Like the 2.2mF to 100mF units I normally use?

---
Pretty large value for ceramics, eh?
---

Never seen any warnings. They are not piezoelectric.

---
It's not necessary for a capacitor to be piezoelectric to exhibit a
mechanical resonance or to be microphonic. All that's required is for
the dielectric to be mechanically deformable by the forces exerted by
the electric field across it or for the dielectric to be deformed by
external mechanical forces.

--
John Fields

 

[Terry Given]

Clarence wrote:

"Terry Given" wrote

Clarence wrote:

"Terry Given" <my_name@ieee.org> wrote in message
snip


Thanks for the warning about Macon. I'll avoid them!

Actually its not Marcon per se, its just that the larger ceramic caps
have mechanical resonance's that can be excited electrically. square-loop
ferrite has the same problem - witness the warnings in the Ferroxcube
databook.

Cheers
Terry


Like the 2.2mF to 100mF units I normally use?

Never seen any warnings. They are not piezoelectric.

you use 0.1 farad ceramic caps? those I'd like to see. Whats the
dielectric? (or perhaps you use "mF" to mean micro-Farads - quaint but
confusing, given the preponderance of SI units nowadays). I did once see
a 100uF 200V (IIRC) NPO cap (mil smps). very very expensive - US$300 IIRC.

AFAICR the piezoelectric behaviour was not the issue - just electrically
exciting them at their mechanical resonant frequencies.


Cheers
Terry

 

[Terry Given]

John Fields wrote:

On Thu, 02 Dec 2004 23:06:21 GMT, "Clarence" <no@No.com> wrote:



Like the 2.2mF to 100mF units I normally use?


---
Pretty large value for ceramics, eh?
---


Never seen any warnings. They are not piezoelectric.


---
It's not necessary for a capacitor to be piezoelectric to exhibit a
mechanical resonance or to be microphonic. All that's required is for
the dielectric to be mechanically deformable by the forces exerted by
the electric field across it or for the dielectric to be deformed by
external mechanical forces.

And if the mechanical resonant frequency is the same as the electrical
excitation, significant (wrt the cap) forces can build up over time.
2220 and bigger were noted in the Marcon paper.

Cheers
Terry

 

[Clarence]

"Terry Given" <my_name@ieee.org> wrote in message
news:ZZOrd.21704$9A.354354@news.xtra.co.nz...

Clarence wrote:

"Terry Given" wrote

Clarence wrote:

"Terry Given" <my_name@ieee.org> wrote in message
snip


Thanks for the warning about Macon. I'll avoid them!
Actually its not Marcon per se, its just that the larger ceramic caps
have mechanical resonance's that can be excited electrically. square-loop
ferrite has the same problem - witness the warnings in the Ferroxcube
databook.
Cheers > >>Terry

Like the 2.2mF to 100mF units I normally use?

Never seen any warnings. They are not piezoelectric.

C4532X7R2A225M By TDK 2.2uF 100V (since your into SI (stupid interference))
Up to and including C4532Y5V1A107Z 100uF 10V
And NOJC107M004RWJ 100uF 4V Y5V

These are all 1812 SMT parts.

you use 0.1 farad ceramic caps? those I'd like to see. What's the
dielectric? (or perhaps you use "mF" to mean micro-Farads - quaint but
confusing, given the preponderance of SI units nowadays). I did once see
a 100uF 200V (IIRC) NPO cap (mil smps). very very expensive - US$300 IIRC.

AFAICR the piezoelectric behavior was not the issue - just electrically
exciting them at their mechanical resonant frequencies.

Electrical excitation to mechanical resonance is the DEFINITION of
"piezoelectric."

 

[Leif Erickson]

Watson A.Name - "Watt Sun, the Dark Remover" wrote:

"Howard Long" <howard@howardlongxxx.com> wrote in message
news:comr7t$441$1@sparta.btinternet.com...
[snip]


I think I also need a smaller soldering iron tip - the last one was

still

too big and bulky with a 1 or 2 mm point.

Here's the iron I use


http://www.maplin.co.uk/Module.aspx?ModuleNo=10271&TabID=1&source=15&Wor
ldID=9&doy=2m12

I read the text in that ad three times, and I still couldn't find
anything that said what the wattage was. Why would they leave out
someething so important?


I use the same sized tip that was supplied with the iron - it's pointy

but

not miniscule.

Cheers, Howard



Hi there Jack

Check out http://protoboards.theshoppe.com/articles.html

for some soldering advice. There is a basic soldering and SMD article on
there, and SMD breadboards.

You should be able to put the chip on by hand. I do.

1.You need a good HANDS FREE magnifier, one of them geeky head set
flip-up magnifiers. OPTI-VISOR is one I use, and can get different
lenses for them and has a little monacle magnifier that you push over 1
eye to see even closer. A bench mounted, spring folding magnifier and
lamp combo can work, or a goose neck one with a heavy base. You got to
have both hands free to see, and work. Do not try them stupid little
tweezer/magnifier combo deals for $3-5, they are worthless. And you
usually are not lined up to see into it while soldering.

2. Get a low wattage iron, 10-20 Watts, or so. Don't need a lot of heat
for the chips. Ebay has Metcal MPX style soldering iron sets with a iron
and a stand. They are first or 2nd generation now, but still way better
than ANYTHING on the market for soldering. 5-10 second warm up times.
2nd generation power supply unit has 2 iron connectors! 1st gen. has
only 1 iron connector on it. They all use the same type of tips, and can
get IC size tips, 0603-1210 size tips, many other special ones. What you
need for IC's is a HOOF tip. Its an angled tip, with a depression in the
end, to hold some solder.

3. Tack solder the chip on 1 corner. Put TINY bit of solder on a corner
pad. Get chip in right PIN #1 Position FIRST. AFTER getting the chip in
place, REGISTER the corners and sides so ALL the pins line up. If some
are bent, use the tweezers you have to move them. OF COURSE YOU ARE
WEARING A WRIST STRAP ON AN ESD MAT!!!!!
Solder 1 corner, and make it quick, no more than 5-7 seconds on a pad.
RE-REGISTER THE OPPOSITE CORNER, and solder it down. CHECK ALL PINS
BEFORE COMMITTING YOURSELF!! Then use a lot of flux, preferably from a
flux pen, and coat the pads and pins good. Then with a WELL TINNED TIP,
put a small bit on the tip, put it on one side of the pins, and
LIGHTLY!! DRAG IT ACROSS PADS/PINS to the end. If not enough solder on
the side, do it again, AFTER fluxing a little more. Flux should keep the
shorts from happening, if you go fast enough, too slow and it may leave
a blob on 2-3 pins. Not to worry. Finish up all sides of chip.

4. FLUX again - Then go back with fine tip and try to drag the blob over
2-4 pins or so, to get rid of short(s). With FINE PITCH 0.8/0.5 mm QFPs
and such, just be a little more careful with pressure on pins. For the
0.5 mm you will need a good magnifier. You can also use the desoldering
braid, SODER-WICK, or some type of braid to pull solder shorts off pins.

5. You WILL need a good magnifier, a DECENT iron and different types of
tips, 1-2 different type of tweezers, and a flux pen for all SMD type
soldering. I have a bent fine point pair of tweezers, for the tiny stiff
and picking up QFP's by 1 pin! And a thicker, straight utility pair,
with square tips for bending the wires, or getting a better grip, and
general use, as its a heavy pair. Contact East, Techni-tool, or any
electronics catalog should have what you need. Some tools may cost, like
the tweezers, but they are for life, unless you drop the fine tip one on
the floor!

Hope this helps out.

Leif Erickson

 

[Larry Brasfield]

"Clarence" <no@No.com> wrote in message news:JfQrd.27826$zx1.15327@newssvr13.news.prodigy.com...

Electrical excitation to mechanical resonance is the DEFINITION of
"piezoelectric."

No, that is not right at all. A material can be piezoelectric
even when configured such that no resonance can occur.
Mechanical resonance is an extensive property, applicable
to a specific object with particular boundaries. In contrast,
a material itself, (regardless of its shape), has piezoelectic
parameters defining an intensive property, applicable to
infinitessimal volumes.

Perhaps, if you are going to "correct" people and set out
to "educate" them, you should be careful that you are not
simply throwing out some vague notions that you have
inadvertantly collected.

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.

 

[Clarence]

"Larry Brasfield" <donotspam_larry_brasfield@hotmail.com> wrote in message
news:2OSrd.386$et5.51571@news.uswest.net...

"Clarence" <no@No.com> wrote in message
news:JfQrd.27826$zx1.15327@newssvr13.news.prodigy.com...
Electrical excitation to mechanical resonance is the DEFINITION of
"piezoelectric."

No, that is not right at all. A material can be piezoelectric
even when configured such that no resonance can occur.
Mechanical resonance is an extensive property, applicable
to a specific object with particular boundaries. In contrast,
a material itself, (regardless of its shape), has piezoelectric
parameters defining an intensive property, applicable to
infinitesimal volumes.

Perhaps, if you are going to "correct" people and set out
to "educate" them, you should be careful that you are not
simply throwing out some vague notions that you have
inadvertently collected.
--
--Larry Brasfield
email: larry_brasfield@hotmail.com
Above views may belong only to me.

I am not sure I understand what your trying to say. It appears to be
speculation.
I was about to reply, then I read your disavowal. I see you are aware that you
are only vaguely familiar with the phenomena. A piezoelectric material which
has not been shaped, or which has no electrodes attached to excite the
piezoelectric properties is not affected in a predictable manner. So if a
material with those piezoelectric is applied in a product it "MAY" behave in a
way which creates stress. However AFAIK piezoelectric quartz, barium titanate,
or other piezoelectric materials are NOT routinely used in the production of
capacitors. It takes relatively high voltages to get much movement in
piezoelectric materials. Lose molecules would not have any effect at all since
it is the matrix of crystal formation which exhibits the property.

I designed equipment to solder leads on crystals and we measured the flexure in
tens of micro inches. Placing material in a position where movement was
inhibited, as in a potting compound, reduced movement to fractions of a micro
inches. Resonance would vanish with inhibiting pressure applied.

Unlike a ferrite, or crystal quartz, alumna used for SMT components do not
exhibit piezoelectric properties.

If your aware of any other piezoelectric materials please list them. I can
think of many applications for a low cost piezoelectric operated mechanical
device.

BTW: The soldering process should Twine the piezoelectric material if it was
present. Heat destroys the piezoelectric properties in the same manner as
magnets are demagnetized.

 

[Ian]

"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com> wrote
in message news:10qu79bmj3df450@corp.supernews.com...

"Howard Long" <howard@howardlongxxx.com> wrote in message
news:comr7t$441$1@sparta.btinternet.com...
[snip]

I think I also need a smaller soldering iron tip - the last one was
still
too big and bulky with a 1 or 2 mm point.

Here's the iron I use

http://www.maplin.co.uk/Module.aspx?ModuleNo=10271&TabID=1&source=15&Wor
ldID=9&doy=2m12

I read the text in that ad three times, and I still couldn't find
anything that said what the wattage was. Why would they leave out
someething so important?

Look in the FAQ tab - 48W.

Regards
Ian

 

[John Fields]

On Fri, 03 Dec 2004 02:33:13 GMT, "Clarence" <no@No.com> wrote:

"Terry Given" <my_name@ieee.org> wrote in message
news:ZZOrd.21704$9A.354354@news.xtra.co.nz...

AFAICR the piezoelectric behavior was not the issue - just electrically
exciting them at their mechanical resonant frequencies.

Electrical excitation to mechanical resonance is the DEFINITION of
"piezoelectric."

---
Frayed knot, Clarence.

Also wrong:

1. Your statement, in another post, that piezoelectric materials
aren't use in the manufacture of ceramic capacitors. Check it out
and you'll find that barium titanate is quite often used as a
dielectric.

2. From another post, you imply that "alumna" is used for the
dielectric in surface-mount caps. I don't believe that's true, and
I believe that what you're referring to is "alumina",
(aluminum oxide) the material which is used for the substrate of
surface mount _resistors_. Take a look at the dielectric constant
of alumina VS that of barium titanate for a clue.

You also seem to be laboring under the misapprehension that merely
shaping a material like barium titanate will imbue it with
piezoelectric characteristics. It will not; poling is a necessary
step in the process and, while it can occur spontaneously under
certain circumstances, it's usually forced.

All of this information is available by Googling for it and you do
yourself a great disservice by not availaing yourself of it before you
"Open mouth, insert foot".

--
John Fields

 

[Clarence]

"Ken Smith" <kensmith@green.rahul.net> wrote in message
news:coq4c5$s69$3@blue.rahul.net...

In article <JDUrd.53480$QJ3.45347@newssvr21.news.prodigy.com>,
Clarence <no@No.com> wrote:
[...]
If your aware of any other piezoelectric materials please list them. I can
think of many applications for a low cost piezoelectric operated mechanical
device.

Both X7R and X5R are slightly piezoelectric. Neither is good enough to be
put to practical use as an actuator. If you put about 500mA at 2KHz
through a 2.2uF X7R cap mounted on a PCB you get just enough motion that
you can hear it.

500mA is a rather substantial level of power for that value. It takes 39.3
Volts sinusoidal directly across the cap. I could find no part which is rated
to withstand that level of ripple current at these frequencies. All were rated
for .03 to .09 ohms ESR for frequencies over 100KHz.

Somewhere around here, I have a paper by Advanced Technical Ceramics which
talks about this subject. They had quite a nice collection of reference
material related to the use of ceramic capacitors in RF power
applications.

As little as a reliable motion of 0.002 for a 100V bias would be useful.
Assume a bar shape for maximum deflection.

So how much motion do you get at 100KHz? The entire unit is 0.180 long, 0.120
wide, and 0.080 high (max) with tolerances of +/- 0.010 Inches. The cap
element is coated with a resilient encapsulate.

The AC component is 30VRMS max and the DC is 80V.
I find nothing that confirms the property, nor the magnitude of the motion.
BTW, NASA, and FAA do not provide any warnings on these devices.

How about the X5V material?

 

[John Fields]

On Fri, 03 Dec 2004 18:21:19 GMT, "Clarence" <no@No.com> wrote:

"Ken Smith" <kensmith@green.rahul.net> wrote in message
news:coq4c5$s69$3@blue.rahul.net...
In article <JDUrd.53480$QJ3.45347@newssvr21.news.prodigy.com>,
Clarence <no@No.com> wrote:
[...]
If your aware of any other piezoelectric materials please list them. I can
think of many applications for a low cost piezoelectric operated mechanical
device.

Both X7R and X5R are slightly piezoelectric. Neither is good enough to be
put to practical use as an actuator. If you put about 500mA at 2KHz
through a 2.2uF X7R cap mounted on a PCB you get just enough motion that
you can hear it.

500mA is a rather substantial level of power for that value.

---
mA is current. mW is power.
---

It takes 39.3 Volts sinusoidal directly across the cap.

---
???

1 1
Xc = ------- = -------------------- ~ 36 ohms
2pifC 6.28*2000Hz*2.2E-6


E = I Xc = 0.5A * 36 ohms = 18VRMS ~ 50.9VPP
---

I could find no part which is rated
to withstand that level of ripple current at these frequencies. All were rated
for .03 to .09 ohms ESR for frequencies over 100KHz.

---
What levels of ripple current were you able to find which these parts
could withstand at 2.2kHz?
---

As little as a reliable motion of 0.002 for a 100V bias would be useful.
Assume a bar shape for maximum deflection.

So how much motion do you get at 100KHz? The entire unit is 0.180 long, 0.120
wide, and 0.080 high (max) with tolerances of +/- 0.010 Inches. The cap
element is coated with a resilient encapsulate.

The AC component is 30VRMS max and the DC is 80V.
I find nothing that confirms the property, nor the magnitude of the motion.
BTW, NASA, and FAA do not provide any warnings on these devices.

---
If you search the literature, you may find that piezoelectric
actuators lie typically in the microinch of length change per inch of
material per volt of excitation. I think even Edmund might have some.
If not, Google "piezoelectric actuators" for a clue.
---

How about the X5V material?

---
How _about_ the X5V material?

--
John Fields

 

[John Popelish]

Ken Smith wrote:

In article <JDUrd.53480$QJ3.45347@newssvr21.news.prodigy.com>,
Clarence <no@No.com> wrote:
[...]
If your aware of any other piezoelectric materials please list them. I can
think of many applications for a low cost piezoelectric operated mechanical
device.

Both X7R and X5R are slightly piezoelectric. Neither is good enough to be
put to practical use as an actuator. If you put about 500mA at 2KHz
through a 2.2uF X7R cap mounted on a PCB you get just enough motion that
you can hear it.
(snip)

Agreed. I have a little pump and dump LED pulser that charges a 1 uf
100 VDC X7R 1210 smt capacitor. I gcharge it up to 50 volts over 900
us and dump it through the LEDs with a peak current of almost 1 amp in
100 us with the current peak controlled by a series inductance. I can
always tell when the circuit is working by the thin whine emitted.
Mylar caps in the same circuit made no noise.

--
John Popelish