Soldering surface mount components

[Daniel Kelly (AKA Jack)]

Dear Gordon,

Many many thanks for your reply.

I've had a search for the video and can't find it anywhere.

Do you know for sure where I could get hold of it in the UK?

If not, I would be most indepted if I could get a copy from you. Could you
e-mail me a DivX or something?

Many many thanks,
Jack



"Gordon Youd" <gordon@Zgyoud.demon.co.uk> wrote in message
news:ca7fq2$1on$1$8300dec7@news.demon.co.uk...

I have a VHS video demonstrating METCAL Soldering Systems.

They make SMT rework by hand look so simple, like John Larkin said "tack
the
ends and run down the line".

Try CPC Ltd for a copy of the video, it's free.

If you cannot get a copy I can copy mine for you.

The site for Metcal is www.metcal.com, I could not find the video there
but electronic wholesalers have it.

Regards, Gordon.

Remove the Z from my address to reply.

--------------------------------------------------------------------------
--
-----------
"Daniel Kelly (AKA Jack)" <d.kellyNOSPAM@NOSPAM.ucl.ac.uk> wrote in
message
news:ca57k1$1mja$1@uns-a.ucl.ac.uk...
Hi,

I am planning a job where I need to manually solder surface mount ICs.
Some
of these ICs have pins that are only 0.5mm apart! I'm worried that this
will be impossible to solder manually.

I've looked on the web - people tell me it is possible to solder SMDs
but
I'm worried their talking about older SMDs with pin-to-pin distances of
more
like 1mm.

I'm a relatively skilled soldering iron user.

Is it possible to manually solder ICs with pins only 0.5mm apart?

Thanks,
Jack

 

[Daniel Kelly (AKA Jack)]

Dear Gordon,

Actually, don't worry - I've just phoned up Eagle, METCAL's UK supplier, and
they're sending a CD-ROM to me in the post right now! How cool is that?!?
Thanks so much!

Jack



"Daniel Kelly (AKA Jack)" <d.kellyNOSPAM@NOSPAM.ucl.ac.uk> wrote in message
news:ca9e2a$305q$1@uns-a.ucl.ac.uk...

Dear Gordon,

Many many thanks for your reply.

I've had a search for the video and can't find it anywhere.

Do you know for sure where I could get hold of it in the UK?

If not, I would be most indepted if I could get a copy from you. Could
you
e-mail me a DivX or something?

Many many thanks,
Jack



"Gordon Youd" <gordon@Zgyoud.demon.co.uk> wrote in message
news:ca7fq2$1on$1$8300dec7@news.demon.co.uk...
I have a VHS video demonstrating METCAL Soldering Systems.

They make SMT rework by hand look so simple, like John Larkin said "tack
the
ends and run down the line".

Try CPC Ltd for a copy of the video, it's free.

If you cannot get a copy I can copy mine for you.

The site for Metcal is www.metcal.com, I could not find the video
there
but electronic wholesalers have it.

Regards, Gordon.

Remove the Z from my address to reply.


--------------------------------------------------------------------------
--
-----------
"Daniel Kelly (AKA Jack)" <d.kellyNOSPAM@NOSPAM.ucl.ac.uk> wrote in
message
news:ca57k1$1mja$1@uns-a.ucl.ac.uk...
Hi,

I am planning a job where I need to manually solder surface mount ICs.
Some
of these ICs have pins that are only 0.5mm apart! I'm worried that
this
will be impossible to solder manually.

I've looked on the web - people tell me it is possible to solder SMDs
but
I'm worried their talking about older SMDs with pin-to-pin distances
of
more
like 1mm.

I'm a relatively skilled soldering iron user.

Is it possible to manually solder ICs with pins only 0.5mm apart?

Thanks,
Jack

 

[Cyclonus]

On Thu, 10 Jun 2004 11:56:38 +0100, "Daniel Kelly \(AKA Jack\)"
<d.kellyNOSPAM@NOSPAM.ucl.ac.uk> wrote:

Dear Gordon,

Actually, don't worry - I've just phoned up Eagle, METCAL's UK supplier, and
they're sending a CD-ROM to me in the post right now! How cool is that?!?
Thanks so much!

Jack

Wow, thats really great, I suppose you wouldnt know whom I could

contact in Canada to get a copy of that CD??

Maurice

"Daniel Kelly (AKA Jack)" <d.kellyNOSPAM@NOSPAM.ucl.ac.uk> wrote in message
news:ca9e2a$305q$1@uns-a.ucl.ac.uk...
Dear Gordon,

Many many thanks for your reply.

I've had a search for the video and can't find it anywhere.

Do you know for sure where I could get hold of it in the UK?

If not, I would be most indepted if I could get a copy from you. Could
you
e-mail me a DivX or something?

Many many thanks,
Jack



"Gordon Youd" <gordon@Zgyoud.demon.co.uk> wrote in message
news:ca7fq2$1on$1$8300dec7@news.demon.co.uk...
I have a VHS video demonstrating METCAL Soldering Systems.

They make SMT rework by hand look so simple, like John Larkin said "tack
the
ends and run down the line".

Try CPC Ltd for a copy of the video, it's free.

If you cannot get a copy I can copy mine for you.

The site for Metcal is www.metcal.com, I could not find the video
there
but electronic wholesalers have it.

Regards, Gordon.

Remove the Z from my address to reply.


--------------------------------------------------------------------------
--
-----------
"Daniel Kelly (AKA Jack)" <d.kellyNOSPAM@NOSPAM.ucl.ac.uk> wrote in
message
news:ca57k1$1mja$1@uns-a.ucl.ac.uk...
Hi,

I am planning a job where I need to manually solder surface mount ICs.
Some
of these ICs have pins that are only 0.5mm apart! I'm worried that
this
will be impossible to solder manually.

I've looked on the web - people tell me it is possible to solder SMDs
but
I'm worried their talking about older SMDs with pin-to-pin distances
of
more
like 1mm.

I'm a relatively skilled soldering iron user.

Is it possible to manually solder ICs with pins only 0.5mm apart?

Thanks,
Jack

 

[Gordon Youd]

Maurice, Try their site www.metcal.com

CANADA

EMX
(Manufacturers Rep)
227 Idema Road

Marhkam, ON, L3R 1B1, CANADA

Phone: 905-475-8000
Fax: 905-475-2300
Email: sales@emx.ca

--------------------------------------------------------------------------

EMX
(Manufacturers Rep)
5950 Frued #23

Montreal, PQ, H4S 1T1, CANADA

Phone: 514-484-6565
Fax: 514-482-2221
Email: sales@emx.ca

--------------------------------------------------------------------------

Adtool
(Distributor)
10 Ronald Drive

Montreal, Quebec, H4X 1M8, CANADA

Phone: 514-482-2548
Fax:
Email:

--------------------------------------------------------------------------

Adtool
(Distributor)
141 6200 MacKay Ave.

Burnaby, B. C., V5H 4M9, CANADA

Phone: 604-618-2924
Fax:
Email:

--------------------------------------------------------------------------


Regards, Gordon.
----------------------------------------------------------------



"Cyclonus" <xycyclonusxy@NOSPAMhotmail.com> wrote in message
news:s6khc0d3rolbebe4jpea4bneiaps92gdee@4ax.com...

On Thu, 10 Jun 2004 11:56:38 +0100, "Daniel Kelly \(AKA Jack\)"
d.kellyNOSPAM@NOSPAM.ucl.ac.uk> wrote:

Dear Gordon,

Actually, don't worry - I've just phoned up Eagle, METCAL's UK supplier,
and
they're sending a CD-ROM to me in the post right now! How cool is
that?!?
Thanks so much!

Jack

Wow, thats really great, I suppose you wouldnt know whom I could
contact in Canada to get a copy of that CD??

Maurice

 

[Michael Schwingen]

In article <40c77888$0$21346$5402220f@news.sunrise.ch>,
Rene Tschaggelar <none@none.net> wrote:

Then I use fluxpaste from a syringe, heated with the heatgun to make it
more liquid.

Metcal has a nice Fluxpen ("FP-1") with a brush-like tip and
squeeze-dispenser that works very well when filled with liquid flux - I use
no-clean flux, which is non-sticky, but it should also work with rosin flux.

cu
Michael

 

[Cyclonus]

On Thu, 10 Jun 2004 23:06:41 +0100, "Gordon Youd"
<gordon@Zgyoud.demon.co.uk> wrote:
Thanks!, I sent a request off the the local Canadian office.

Maurice

Maurice, Try their site www.metcal.com

CANADA

EMX
(Manufacturers Rep)
227 Idema Road

Marhkam, ON, L3R 1B1, CANADA

Phone: 905-475-8000
Fax: 905-475-2300
Email: sales@emx.ca

--------------------------------------------------------------------------

EMX
(Manufacturers Rep)
5950 Frued #23

Montreal, PQ, H4S 1T1, CANADA

Phone: 514-484-6565
Fax: 514-482-2221
Email: sales@emx.ca

--------------------------------------------------------------------------

Adtool
(Distributor)
10 Ronald Drive

Montreal, Quebec, H4X 1M8, CANADA

Phone: 514-482-2548
Fax:
Email:

--------------------------------------------------------------------------

Adtool
(Distributor)
141 6200 MacKay Ave.

Burnaby, B. C., V5H 4M9, CANADA

Phone: 604-618-2924
Fax:
Email:

--------------------------------------------------------------------------


Regards, Gordon.
----------------------------------------------------------------



"Cyclonus" <xycyclonusxy@NOSPAMhotmail.com> wrote in message
news:s6khc0d3rolbebe4jpea4bneiaps92gdee@4ax.com...
On Thu, 10 Jun 2004 11:56:38 +0100, "Daniel Kelly \(AKA Jack\)"
d.kellyNOSPAM@NOSPAM.ucl.ac.uk> wrote:

Dear Gordon,

Actually, don't worry - I've just phoned up Eagle, METCAL's UK supplier,
and
they're sending a CD-ROM to me in the post right now! How cool is
that?!?
Thanks so much!

Jack

Wow, thats really great, I suppose you wouldnt know whom I could
contact in Canada to get a copy of that CD??

Maurice

 

[Hans Summers]

You people are all talking about flux, solder flows, PCB's, but you've got
it all wrong!

You should take a look at my page
http://www.hanssummers.com/electronics/equipment/spectrumanalyser2/index.htm
.. About 2/3 the way down you'll see a closeup photo on the left hand side,
showing a 24-pin TSSOP packaged ADC chip. The pin spacing is 0.65mm (Ok, so
not quite your 0.5mm). You can click the picture for a larger version.

I did this with:

NO magnifying glass
NO special lighting
NO hot air etc
NO special soldering iron, just my old 18W Antex CS
NO special bit, just my Antex 1mm bit type 1106
NO special solder or flux, just ordinary 22swg 60/40 multicore fluxed solder
NO pre-etched PCB, just a piece of PCB stock I cut some pads in with a cheap
plastic craft knife
NO fancy rigs to hold the work, just loose on the bench, with the IC glued
to the board

And it worked first time.

I've soldered other SMD IC's too, but this one was the most extreme. You'll
also find less tiny spacing'ed SMD IC's soldered on these pages of my site:

http://www.hanssummers.com/radio/polyphase/index.htm
http://www.hanssummers.com/radio/ozon/index.htm
http://www.hanssummers.com/computers/newz80/intro.htm
http://www.hanssummers.com/electronics/equipment/riskometer/index.htm

Anything's possible ;-)

Hans
http://www.HansSummers.com

 

[Chuck Olson]

"Hans Summers" <hans.summers@tudor.com> wrote in message
news:2j5kp9FtfhvvU1@uni-berlin.de...

You people are all talking about flux, solder flows, PCB's, but you've got
it all wrong!

You should take a look at my page

http://www.hanssummers.com/electronics/equipment/spectrumanalyser2/index.htm
. About 2/3 the way down you'll see a closeup photo on the left hand side,
showing a 24-pin TSSOP packaged ADC chip. The pin spacing is 0.65mm (Ok,
so
not quite your 0.5mm). You can click the picture for a larger version.

I did this with:

NO magnifying glass
NO special lighting
NO hot air etc
NO special soldering iron, just my old 18W Antex CS
NO special bit, just my Antex 1mm bit type 1106
NO special solder or flux, just ordinary 22swg 60/40 multicore fluxed
solder
NO pre-etched PCB, just a piece of PCB stock I cut some pads in with a
cheap
plastic craft knife
NO fancy rigs to hold the work, just loose on the bench, with the IC glued
to the board

And it worked first time.

I've soldered other SMD IC's too, but this one was the most extreme.
You'll
also find less tiny spacing'ed SMD IC's soldered on these pages of my
site:

http://www.hanssummers.com/radio/polyphase/index.htm
http://www.hanssummers.com/radio/ozon/index.htm
http://www.hanssummers.com/computers/newz80/intro.htm
http://www.hanssummers.com/electronics/equipment/riskometer/index.htm

Anything's possible ;-)

Hans
http://www.HansSummers.com


You must be very near-sighted.

 

[Spehro Pefhany]

On Mon, 14 Jun 2004 16:41:47 GMT, the renowned "Chuck Olson"
<chuckolson01@REMOVETHIScomcast.net> wrote:

"Hans Summers" <hans.summers@tudor.com> wrote in message
news:2j5kp9FtfhvvU1@uni-berlin.de...

You people are all talking about flux, solder flows, PCB's, but you've got
it all wrong!

You should take a look at my page

http://www.hanssummers.com/electronics/equipment/spectrumanalyser2/index.htm

That old Heathkit signal generator is a hoot. Tubes (err, "valves"),
right?


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

 

[Mariano]

So how did you do it then? you forgot to tell us how

- solder tip size?
- solder type?
- ...


"Hans Summers" <hans.summers@tudor.com> wrote in message
news:2j5kp9FtfhvvU1@uni-berlin.de...

You people are all talking about flux, solder flows, PCB's, but you've got
it all wrong!

You should take a look at my page

http://www.hanssummers.com/electronics/equipment/spectrumanalyser2/index.htm
. About 2/3 the way down you'll see a closeup photo on the left hand side,
showing a 24-pin TSSOP packaged ADC chip. The pin spacing is 0.65mm (Ok,
so
not quite your 0.5mm). You can click the picture for a larger version.

I did this with:

NO magnifying glass
NO special lighting
NO hot air etc
NO special soldering iron, just my old 18W Antex CS
NO special bit, just my Antex 1mm bit type 1106
NO special solder or flux, just ordinary 22swg 60/40 multicore fluxed
solder
NO pre-etched PCB, just a piece of PCB stock I cut some pads in with a
cheap
plastic craft knife
NO fancy rigs to hold the work, just loose on the bench, with the IC glued
to the board

And it worked first time.

I've soldered other SMD IC's too, but this one was the most extreme.
You'll
also find less tiny spacing'ed SMD IC's soldered on these pages of my
site:

http://www.hanssummers.com/radio/polyphase/index.htm
http://www.hanssummers.com/radio/ozon/index.htm
http://www.hanssummers.com/computers/newz80/intro.htm
http://www.hanssummers.com/electronics/equipment/riskometer/index.htm

Anything's possible ;-)

Hans
http://www.HansSummers.com

 

[Hans Summers]

"Mariano" <mfilippaREMOVETHIS@uol.com.ar> wrote in message
news:Crlzc.90$gs.867@news.itd.umich.edu...

So how did you do it then? you forgot to tell us how

No, I did tell you (at least, I did tell you those things)... here's my
original relevant sections pasted in again:

- solder tip size?

NO special soldering iron, just my old 18W Antex CS
NO special bit, just my Antex 1mm bit type 1106

- solder type?

NO special solder or flux, just ordinary 22swg 60/40 multicore fluxed
solder

As for process:

This TSSOP had 24 pins (unfortunately the catalogue had claimed in was DIL,
but in reality it was SMD. Pity I didn't read the datasheet carefully enough
and match up the part numbers).

So anyway, I carved two columns of small pads on the surface of the unetched
PCB using a knife (one of those ubiquitous dirt cheap orange "craft"
knives). 2 columns of 6 on each side of the chip, makes 24. I couldn't do 12
per side because they would have been too narrow for me to cut with that
knife. I left a space in between the pairs of columns either side, for the
IC.

The IC was glued in position. Now alternate pins on the TSSOP are bent
upwards. So considering the left hand side, pins 1, 3, 5, 7, 9, 11 continue
resting on the newly carved first column of 5 pads. Pins 2, 4, 6, 8, 10, 12
are bent upwards away from the board. Then I took ordinary multi-core wire,
and took single copper strands from it. These pins 2, 4, 6 etc were
connected to the outer column of 6 pads using these thin copper strands.
Bending alternate pins of the IC in opposite directions makes it possible to
solder to the pins even with this 1mm iron bit.

Have another look at the picture,
http://www.hanssummers.com/electronics/equipment/spectrumanalyser2/index.htm
and you will be able to see some of the things I'm talking about (the
columns of carved pads etc).

Hans
http://www.HansSummers.com

 

[Hans Summers]

You must be very near-sighted.

No, not at all. You should probably be worried about my sanity though ;-)

Hans
http://www.HansSummers.com

 

[Hans Summers]

"Spehro Pefhany" <speffSNIP@interlogDOTyou.knowwhat> wrote in message
news:idnrc0prkf0k6co7b9p899vt2d86375ehj@4ax.com...

On Mon, 14 Jun 2004 16:41:47 GMT, the renowned "Chuck Olson"
chuckolson01@REMOVETHIScomcast.net> wrote:


"Hans Summers" <hans.summers@tudor.com> wrote in message
news:2j5kp9FtfhvvU1@uni-berlin.de...

You people are all talking about flux, solder flows, PCB's, but you've
got
it all wrong!

You should take a look at my page


http://www.hanssummers.com/electronics/equipment/spectrumanalyser2/index.ht
m


That old Heathkit signal generator is a hoot. Tubes (err, "valves"),
right?

Right, valves ;-) I forget the valve types. If I recall it contains only
two valves, but I might be remembering wrongly. You can find a large picture
of it here:
http://www.hanssummers.com/electronics/equipment/signalgenerator/sig.htm . I
did open it and take some photos of the insides, but I got the focus all
wrong and didn't bother to re-open it again. I've even got a copy of most of
the manual, sent to me by an Irish radio amateur who has the same generator.

Hans
http://www.HansSummers.com

 

[Steven McGahey]

Hi all,

I've read this thread with a lot of interest, as I have a small bit of
surface-mount work to do, but no experience working with these tiny
components.

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.

Can someone straighten me out on this subject, as I have a feeling that
Nokia will want me to purchase a new phone circuit-board (~Ł70) if I ask
them to repair it, when it's only a minor soldering job that is required.

Thanks in advance,
- Steve

"Daniel Kelly (AKA Jack)" <d.kellyNOSPAM@NOSPAM.ucl.ac.uk> wrote in message
news:ca57k1$1mja$1@uns-a.ucl.ac.uk...

Hi,

I am planning a job where I need to manually solder surface mount ICs.
Some
of these ICs have pins that are only 0.5mm apart! I'm worried that this
will be impossible to solder manually.

I've looked on the web - people tell me it is possible to solder SMDs but
I'm worried their talking about older SMDs with pin-to-pin distances of
more
like 1mm.

I'm a relatively skilled soldering iron user.

Is it possible to manually solder ICs with pins only 0.5mm apart?

Thanks,
Jack

 

[John Larkin]

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

Hi all,

I've read this thread with a lot of interest, as I have a small bit of
surface-mount work to do, but no experience working with these tiny
components.

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.

Can someone straighten me out on this subject, as I have a feeling that
Nokia will want me to purchase a new phone circuit-board (~Ł70) if I ask
them to repair it, when it's only a minor soldering job that is required.

Thanks in advance,
- Steve

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.

I have seen some surfmount LEDs turn to putty when hand soldered. The
transparent plastics seem to be fragile.

John

 

[Larry Brasfield]

"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.

....

John

--
--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: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, and Boy, you had some pretty lousy
assembly people. 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. We tested for very long periods on many
boards. Of course we also inspected the boards before applying power and
checking for damage. Rarely had to retouch a board after the first three.

 

[Terry Given]

Larry Brasfield wrote:

"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.

...

John

This is a VERY good point. Reflow ovens have very well controlled
thermal profiles, slowly ramping temperature to a plateau, holding,
slowly ramping up to final tmep, holding etc. Mostly to avoid this
thermal shock related mechanical failure mechanism. High voltage
ceramics are especially prone to this - hand soldering them is a risky
process.

I once used 2 x 15nF 1000V smt X7R caps in series across an 80-800Vdc
supply for a smps application. During testing one smps failed
catastrophically (two others ran fine). Detailed examination of the
corpse showed a blast pattern radiating outward from one of the caps,
which had ruptured. The resulting mess sprayed directly across the legs
of one of the FETs, thereby toasting the unit. At the time it was
operating at a DC bus voltage of around 400V, so the cap was nowhere
near its rated voltage, more like 20%. One of the guys I worked with had
extensive experience in this area (hi-rel smps hybrids for
il/aerospace), and showed us what went wrong. We immediately replaced
the capacitors, carefully using a manual hot air station, to both
preheat and solder. The units operated continuously into a dead short at
800Vdc, no problems - there were other issues of course, it was a
pre-production protoype, but none of the explosive kind.

Cheers
Terry

 

[Larry Brasfield]

"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?)

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.

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.

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.

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

 

[Howard Long]

"Steven McGahey" <steven.doesntneedthis.mcgahey@virgin.theISP.net (remove
the obvious bits)> wrote in message
news:IW3rd.1515$ck3.1414@newsfe6-gui.ntli.net...

Hi all,

I've read this thread with a lot of interest, as I have a small bit of
surface-mount work to do, but no experience working with these tiny
components.

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.

FWIW, I use a standard temperature controlled iron with a small tip (I think
it cost about $50), with very thin solder, desolder braid.

I do everyting on a plain white tray with lips around the edge - there's
nothing worse than losing that last 3.3k resistor you had on the carpet...

I do have a small magnifying glass, but that's just to help me identify the
components that actually have markings - I don't use it for anything else.

For the chips with loads of pins at tiny spacing (including 0.5mm), I use a
really tiny piece of bluetak (a bit like plasticine or playdoh, but sticks
paper to walls) to fix the component into place, then I solder the
component. I don't worry too much about solder bridges over the leads for
now, but I am rather careful to use small amounts of solder, in case it
creeps under the chip.

Then I use the desolder braid to mop up the excess solder. After a visual
inspection, I do a continuity check of each of the leads to ensure there's
connection to the pcb as well as no shorts between adjacent leads of the
chip. A pain, and almost every time it shows nothing untoward.

Rework involving removal of chips takes a number of tricks, but primarily
remember that you're much more interested in maintaining the PCB in good
shape, at the expense of a trashed component.

Good luck. Howard.