Breaking the epoxy bond under SMD ?

[N_Cook]

Transistors , in this case 1-amp-continuous "size" whatever the SO
designation of that is.
If I've not used hot air then a scalpel tip or needle point, as used here,
wedged under , soldering iron melt solder a touch leting the pins relieve
themselves away from the lands , repeat wedging/desolder until fully free.
But this time the epoxy was more structural than just for placement.
I ended up breaking up the transistor body and the epoxy stayed resolute.
Any advice for next time ? if relevant red colour and more than a micro-dot
must have been under it as traces splurged out all around the body.

 

[William Sommerwerck]

"N_Cook" <diverse@tcp.co.uk> wrote in message
news:jshpn0$6d3$1@dont-email.me...

Transistors , in this case 1-amp-continuous "size" whatever the SO
designation of that is.
If I've not used hot air then a scalpel tip or needle point, as used here,
wedged under , soldering iron melt solder a touch leting the pins relieve
themselves away from the lands , repeat wedging/desolder until fully free.
But this time the epoxy was more structural than just for placement.
I ended up breaking up the transistor body and the epoxy stayed resolute.
Any advice for next time? if relevant red colour and more than a micro-dot
must have been under it as traces splurged out all around the body.

"In this case, the SMD was a one-ampere-capacity transistor.

"I wedged a scalpel tip (a needle point might work, too) under the device. I
then touched a soldering iron to the pins, expecting that unsoldering them
would allow the chip to pop loose. Apparently, though, the epoxy had been
applied to keep the transistor forever in place, rather than just long
enough for the initial soldering. I ended up breaking the transistor, while
the epoxy remained intact.

"Any advice for next time?"

I'm biting my tongue.


"if relevant red colour and more than a micro-dot must have been under it as
traces splurged out all around the body."

I can only make the vaguest of guesses as to what Mr Cook was trying to get
at.

 

[N_Cook]

<dansabrservices@yahoo.com> wrote in message
news:7660ce48-f001-4fb4-86ef-f3785f024b57@googlegroups.com...

On Thursday, June 28, 2012 10:29:12 AM UTC-4, N_Cook wrote:
Transistors , in this case 1-amp-continuous "size" whatever the SO
designation of that is.
If I've not used hot air then a scalpel tip or needle point, as used
here,
wedged under , soldering iron melt solder a touch leting the pins
relieve
themselves away from the lands , repeat wedging/desolder until fully
free.
But this time the epoxy was more structural than just for placement.
I ended up breaking up the transistor body and the epoxy stayed
resolute.
Any advice for next time ? if relevant red colour and more than a
micro-dot
must have been under it as traces splurged out all around the body.

I have successfuly used ChipQuik to free up the solder connections and
then applying a bit of heat to the transistor itself with a little prying

with a screwdriver. The heat helps loosen the epoxy a bit allowing the
removal.

Dan

Your mention of screwdriver - I'd forgotten about my jeweller's finest
screwdriver with the blade I'd ground angles, either side , to
give close to a point. Insert under and twist 1/4 of a turn. I'd only used
it under ICs before, where there is a bit more space , out to the pins.
Have
to check my drawer of ancillary "tools & kit" to check its still there and
more importantly remember to try it next time

 

On Thursday, June 28, 2012 10:29:12 AM UTC-4, N_Cook wrote:

Transistors , in this case 1-amp-continuous "size" whatever the SO
designation of that is.
If I've not used hot air then a scalpel tip or needle point, as used here,
wedged under , soldering iron melt solder a touch leting the pins relieve
themselves away from the lands , repeat wedging/desolder until fully free.
But this time the epoxy was more structural than just for placement.
I ended up breaking up the transistor body and the epoxy stayed resolute.
Any advice for next time ? if relevant red colour and more than a micro-dot
must have been under it as traces splurged out all around the body.

I have successfuly used ChipQuik to free up the solder connections and then applying a bit of heat to the transistor itself with a little prying with a screwdriver. The heat helps loosen the epoxy a bit allowing the removal.

Dan

 

[Gareth Magennis]

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:jshqkd$cr2$1@dont-email.me...

"N_Cook" <diverse@tcp.co.uk> wrote in message
news:jshpn0$6d3$1@dont-email.me...

Transistors , in this case 1-amp-continuous "size" whatever the SO
designation of that is.
If I've not used hot air then a scalpel tip or needle point, as used
here,
wedged under , soldering iron melt solder a touch leting the pins relieve
themselves away from the lands , repeat wedging/desolder until fully
free.
But this time the epoxy was more structural than just for placement.
I ended up breaking up the transistor body and the epoxy stayed resolute.
Any advice for next time? if relevant red colour and more than a
micro-dot
must have been under it as traces splurged out all around the body.

"In this case, the SMD was a one-ampere-capacity transistor.

"I wedged a scalpel tip (a needle point might work, too) under the device.
I
then touched a soldering iron to the pins, expecting that unsoldering them
would allow the chip to pop loose. Apparently, though, the epoxy had been
applied to keep the transistor forever in place, rather than just long
enough for the initial soldering. I ended up breaking the transistor,
while
the epoxy remained intact.

"Any advice for next time?"

I'm biting my tongue.


"if relevant red colour and more than a micro-dot must have been under it
as
traces splurged out all around the body."

I can only make the vaguest of guesses as to what Mr Cook was trying to
get
at.

Hey William, I've found something that I think is just for you.

Here it is:
http://teachempathy.com/self-empathy/empathy-as-a-way-of-being-retreat/

I'm sure they are lovely people, and you will have a whale of a time.


I'm guessing you were some kind of teacher, or Headmaster even, in your
darker, younger days.
Perhaps its time to let go of all that now, and embrace something a little
more worthwhile.



Namaste.

 

[William Sommerwerck]

Hey William, I've found something that I think is just for you.
Here it is:
http://teachempathy.com/self-empathy/empathy-as-a-way-of-being-retreat/
I'm sure they are lovely people, and you will have a whale of a time.

I'm guessing you were some kind of teacher, or Headmaster even,
in your darker, younger days.
Perhaps its time to let go of all that now, and embrace something
a little more worthwhile.

I'm trying to help the guy. You're tolerating his lack of skill. Who's doing
"something ... worthwhile"?

 

[Gareth Magennis]

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:jsianp$nrd$1@dont-email.me...

Hey William, I've found something that I think is just for you.
Here it is:
http://teachempathy.com/self-empathy/empathy-as-a-way-of-being-retreat/
I'm sure they are lovely people, and you will have a whale of a time.

I'm guessing you were some kind of teacher, or Headmaster even,
in your darker, younger days.
Perhaps its time to let go of all that now, and embrace something
a little more worthwhile.

I'm trying to help the guy. You're tolerating his lack of skill. Who's
doing
"something ... worthwhile"?

William, you do not seem to have a clue about what it is to be somebody
other than yourself.

It's not too late to learn.


Gareth.

 

[Gareth Magennis]

"hr(bob) hofmann@att.net" <hrhofmann@att.net> wrote in message
news:7c1e3fff-b970-4bc0-832a-78a5b6b47a16@w24g2000vby.googlegroups.com...

On Jun 28, 4:14 pm, "Gareth Magennis" <sound.serv...@btconnect.com
wrote:
"William Sommerwerck" <grizzledgee...@comcast.net> wrote in message

news:jsianp$nrd$1@dont-email.me...





Hey William, I've found something that I think is just for you.
Here it is:
http://teachempathy.com/self-empathy/empathy-as-a-way-of-being-retreat/
I'm sure they are lovely people, and you will have a whale of a time.

I'm guessing you were some kind of teacher, or Headmaster even,
in your darker, younger days.
Perhaps its time to let go of all that now, and embrace something
a little more worthwhile.

I'm trying to help the guy. You're tolerating his lack of skill. Who's
doing
"something ... worthwhile"?

William, you do not seem to have a clue about what it is to be somebody
other than yourself.

It's not too late to learn.

Gareth.- Hide quoted text -

- Show quoted text -

Mr.Cooks original post was a little confusing, not like his normal
posts, and Mr Sommerweck is normally quite lucid, so he is not quite
as bad a person as you have implied.

That may be so, but I am not basing my posts on this single thread.

Rather, it is based upon an observation of Mr. Sommerweck's recent history
of posting on Usenet.

And this thread is typical of such recent postings, and, IMHO, shows little
understanding of the Human Race.



Gareth.

 

[Paul Drahn]

On 6/28/2012 7:29 AM, N_Cook wrote:

Transistors , in this case 1-amp-continuous "size" whatever the SO
designation of that is.
If I've not used hot air then a scalpel tip or needle point, as used here,
wedged under , soldering iron melt solder a touch leting the pins relieve
themselves away from the lands , repeat wedging/desolder until fully free.
But this time the epoxy was more structural than just for placement.
I ended up breaking up the transistor body and the epoxy stayed resolute.
Any advice for next time ? if relevant red colour and more than a micro-dot
must have been under it as traces splurged out all around the body.



One watt is a lot of power to be dissipating without a heat sink. May I

suggest the epoxy is a heat conducting formula and was there to conduct
the heat to the circuit board material.

Current designs use a device with a metal back side soldered to a large
pad on the circuit board.

Paul

 

[William Sommerwerck]

I'm trying to help the guy. You're tolerating his lack
of skill. Who's doing "something ... worthwhile"?

William, you do not seem to have a clue about what
it is to be somebody other than yourself.

You're absolutely right. If someone has a problem, they ought to work to
overcome it.

If you'd like to take this off line, I'd be happy to continue the
discussion, in a friendly, constructive manner.

 

[William Sommerwerck]

Mr.Cooks original post was a little confusing, not like
his normal posts, and Mr Sommerweck is normally
quite lucid, so he is not quite as bad a person as you
have implied.

The issue is not whether I'm a bad person (I am), but whether anyone should
publicly criticize someone who writes so poorly. I think they should,
especially when a counter-example is provided.

 

[Gareth Magennis]

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:jsikkn$q26$1@dont-email.me...

I'm trying to help the guy. You're tolerating his lack
of skill. Who's doing "something ... worthwhile"?

William, you do not seem to have a clue about what
it is to be somebody other than yourself.

You're absolutely right. If someone has a problem, they ought to work to
overcome it.

William, you are still seeing them as being you.

They are not you, they are somebody else.

You have to try and imagine that possibility.



Gareth.

 

[hr(bob) hofmann@att.net]

On Jun 28, 4:14 pm, "Gareth Magennis" <sound.serv...@btconnect.com>
wrote:

"William Sommerwerck" <grizzledgee...@comcast.net> wrote in message

news:jsianp$nrd$1@dont-email.me...





Hey William, I've found something that I think is just for you.
Here it is:
http://teachempathy.com/self-empathy/empathy-as-a-way-of-being-retreat/
I'm sure they are lovely people, and you will have a whale of a time.

I'm guessing you were some kind of teacher, or Headmaster even,
in your darker, younger days.
Perhaps its time to let go of all that now, and embrace something
a little more worthwhile.

I'm trying to help the guy. You're tolerating his lack of skill. Who's
doing
"something ... worthwhile"?

William, you do not seem to have a clue about what it is to be somebody
other than yourself.

It's not too late to learn.

Gareth.- Hide quoted text -

- Show quoted text -

Mr.Cooks original post was a little confusing, not like his normal
posts, and Mr Sommerweck is normally quite lucid, so he is not quite
as bad a person as you have implied.

 

[Arfa Daily]

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:jshqkd$cr2$1@dont-email.me...

"N_Cook" <diverse@tcp.co.uk> wrote in message
news:jshpn0$6d3$1@dont-email.me...

Transistors , in this case 1-amp-continuous "size" whatever the SO
designation of that is.
If I've not used hot air then a scalpel tip or needle point, as used
here,
wedged under , soldering iron melt solder a touch leting the pins relieve
themselves away from the lands , repeat wedging/desolder until fully
free.
But this time the epoxy was more structural than just for placement.
I ended up breaking up the transistor body and the epoxy stayed resolute.
Any advice for next time? if relevant red colour and more than a
micro-dot
must have been under it as traces splurged out all around the body.

"In this case, the SMD was a one-ampere-capacity transistor.

"I wedged a scalpel tip (a needle point might work, too) under the device.
I
then touched a soldering iron to the pins, expecting that unsoldering them
would allow the chip to pop loose. Apparently, though, the epoxy had been
applied to keep the transistor forever in place, rather than just long
enough for the initial soldering. I ended up breaking the transistor,
while
the epoxy remained intact.

"Any advice for next time?"

I'm biting my tongue.

Because what you really want to say is ... ??

"if relevant red colour and more than a micro-dot must have been under it
as
traces splurged out all around the body."

I can only make the vaguest of guesses as to what Mr Cook was trying to
get
at.

Why are you having to guess at anything, William ? For once, I thought it
was quite clear that he was trying to remove the bloody thing from the board
to replace it with a new one. Obviously, you don't get involved too much
with surface mount reworks, as this is actually quite a common problem.

Arfa
>

 

[Jamie]

Arfa Daily wrote:

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:jshqkd$cr2$1@dont-email.me...

"N_Cook" <diverse@tcp.co.uk> wrote in message
news:jshpn0$6d3$1@dont-email.me...

Transistors , in this case 1-amp-continuous "size" whatever the SO
designation of that is.
If I've not used hot air then a scalpel tip or needle point, as used
here,
wedged under , soldering iron melt solder a touch leting the pins
relieve
themselves away from the lands , repeat wedging/desolder until fully
free.
But this time the epoxy was more structural than just for placement.
I ended up breaking up the transistor body and the epoxy stayed
resolute.
Any advice for next time? if relevant red colour and more than a
micro-dot
must have been under it as traces splurged out all around the body.


"In this case, the SMD was a one-ampere-capacity transistor.

"I wedged a scalpel tip (a needle point might work, too) under the
device. I
then touched a soldering iron to the pins, expecting that unsoldering
them
would allow the chip to pop loose. Apparently, though, the epoxy had been
applied to keep the transistor forever in place, rather than just long
enough for the initial soldering. I ended up breaking the transistor,
while
the epoxy remained intact.

"Any advice for next time?"

I'm biting my tongue.



Because what you really want to say is ... ??





"if relevant red colour and more than a micro-dot must have been under
it as
traces splurged out all around the body."

I can only make the vaguest of guesses as to what Mr Cook was trying
to get
at.


Why are you having to guess at anything, William ? For once, I thought
it was quite clear that he was trying to remove the bloody thing from
the board to replace it with a new one. Obviously, you don't get
involved too much with surface mount reworks, as this is actually quite
a common problem.

Arfa


a little LN usually works

Jamie

 

[Jim Yanik]

"Arfa Daily" <arfa.daily@ntlworld.com> wrote in
news:OE6Hr.647752$kS.617102@fx17.am4:

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:jshqkd$cr2$1@dont-email.me...
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:jshpn0$6d3$1@dont-email.me...

Transistors , in this case 1-amp-continuous "size" whatever the SO
designation of that is.
If I've not used hot air then a scalpel tip or needle point, as used
here,
wedged under , soldering iron melt solder a touch leting the pins
relieve themselves away from the lands , repeat wedging/desolder
until fully free.
But this time the epoxy was more structural than just for placement.
I ended up breaking up the transistor body and the epoxy stayed
resolute. Any advice for next time? if relevant red colour and more
than a micro-dot
must have been under it as traces splurged out all around the body.

"In this case, the SMD was a one-ampere-capacity transistor.

"I wedged a scalpel tip (a needle point might work, too) under the
device. I
then touched a soldering iron to the pins, expecting that unsoldering
them would allow the chip to pop loose. Apparently, though, the epoxy
had been applied to keep the transistor forever in place, rather than
just long enough for the initial soldering. I ended up breaking the
transistor, while
the epoxy remained intact.

"Any advice for next time?"

I'm biting my tongue.


Because what you really want to say is ... ??





"if relevant red colour and more than a micro-dot must have been
under it as
traces splurged out all around the body."

I can only make the vaguest of guesses as to what Mr Cook was trying
to get
at.


Why are you having to guess at anything, William ? For once, I thought
it was quite clear that he was trying to remove the bloody thing from
the board to replace it with a new one. Obviously, you don't get
involved too much with surface mount reworks, as this is actually
quite a common problem.

Arfa

I'm still trying to figure out why epoxy was used to hold a SMD on the
board? thermal-conductive epoxy?

I also can't see epoxy having that tight a grip on the PCB,that it wouldn't
break loose before the SMD package broke. must be some damn good epoxy,wish
I knew who makes it and where to get it!

--
Jim Yanik
jyanik
at
localnet
dot com

 

[William Sommerwerck]

Why are you having to guess at anything, William?

You were apply my final remark to the whole post, rather than to the text
that immediately preceded it. If you look at my rewrite, it's obvious that I
understood /exactly/ what I was trying to do.

 

[William Sommerwerck]

I'm still trying to figure out why epoxy was used to
hold a SMD on the board? Thermal-conductive epoxy?

That must be it, because it would have been "overkill" simply to hold it in
place during the intial soldering.

 

[Jeff Liebermann]

On Thu, 28 Jun 2012 15:29:12 +0100, "N_Cook" <diverse@tcp.co.uk>
wrote:

Transistors , in this case 1-amp-continuous "size" whatever the SO
designation of that is.
(...)

I guess it's too much trouble to supply a usable clue as to what the
device looks like. If it has a plastic or metal back makes a big
difference here. Also, please make an effort to write in complete
sentences that do not require cryptographic decoding.

Nobody uses epoxy to mount SOT transistors in a production
environment. That's because it takes too long for it to set, and
because it crumbles nicely when hot and softens exposed to alcohols
and solvents. Single part epoxy has to be refridgerated in storage,
making use on the production line somewhat awkward. Two part mixes
hard quicker, but have a finite work time. Epoxies (and silicon
rubber compounds) are used to attach physically large components, but
not tiny SOT parts.

More common is cynoacrylate adhesives (aka super-glue) or attaching
components before soldering. If the back of the xsistor is metal, it
gets smeared with solder paste, which acts as a temporary glue, and
then gets reflowed when run through the hot air soldering machinery.
That solders the metal back of the SOT to the PCB.

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

 

[N_Cook]

Jim Yanik <jyanik@abuse.gov> wrote in message
news:XnsA080D89771734jyaniklocalnetcom@216.168.3.44...

"Arfa Daily" <arfa.daily@ntlworld.com> wrote in
news:OE6Hr.647752$kS.617102@fx17.am4:



"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:jshqkd$cr2$1@dont-email.me...
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:jshpn0$6d3$1@dont-email.me...

Transistors , in this case 1-amp-continuous "size" whatever the SO
designation of that is.
If I've not used hot air then a scalpel tip or needle point, as used
here,
wedged under , soldering iron melt solder a touch leting the pins
relieve themselves away from the lands , repeat wedging/desolder
until fully free.
But this time the epoxy was more structural than just for placement.
I ended up breaking up the transistor body and the epoxy stayed
resolute. Any advice for next time? if relevant red colour and more
than a micro-dot
must have been under it as traces splurged out all around the body.

"In this case, the SMD was a one-ampere-capacity transistor.

"I wedged a scalpel tip (a needle point might work, too) under the
device. I
then touched a soldering iron to the pins, expecting that unsoldering
them would allow the chip to pop loose. Apparently, though, the epoxy
had been applied to keep the transistor forever in place, rather than
just long enough for the initial soldering. I ended up breaking the
transistor, while
the epoxy remained intact.

"Any advice for next time?"

I'm biting my tongue.


Because what you really want to say is ... ??





"if relevant red colour and more than a micro-dot must have been
under it as
traces splurged out all around the body."

I can only make the vaguest of guesses as to what Mr Cook was trying
to get
at.


Why are you having to guess at anything, William ? For once, I thought
it was quite clear that he was trying to remove the bloody thing from
the board to replace it with a new one. Obviously, you don't get
involved too much with surface mount reworks, as this is actually
quite a common problem.

Arfa



I'm still trying to figure out why epoxy was used to hold a SMD on the
board? thermal-conductive epoxy?

I also can't see epoxy having that tight a grip on the PCB,that it
wouldn't
break loose before the SMD package broke. must be some damn good
epoxy,wish
I knew who makes it and where to get it!

--
Jim Yanik
jyanik
at
localnet
dot com

Belt and braces , to take the mechanical strain off the solder? To scrape
back the epoxy to a clean board , the action of a soldering iron tip on it,
was like the normal reaction of solder-iron heat to epoxy, goes powdery .
Perhaps its bright red as a warning