Homebrew PCBs

just got the ebay syringe of solder paste...

looks ok so far but i have no idea whatsoever how anyone can apply it with 
the syringe,
pressing the plunger by hand.
Impossible if you ask me.
If you press it the bead comes out much too long, you ned to pull back to 
stop it.

Maybe i'm just too stupid.. i can see 2 small air enclosures in it, which 
definitely
are BAD for this because they are compressible.

I see i have to make a pneumatic dispenser, i worked with such a unit 
before and
it was very convenient.
I guess the syringe adapter will be using quite a bit of hot glue.
I can maybe use it on the cnc later, and i need it anyway because i'm not 
using the cnc for rework
and stuff i guess..

I'll tell you if it worked out then.


ST

--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan 
<stefan_trethan@g...> wrote:
> just got the ebay syringe of solder paste...
> 
> looks ok so far but i have no idea whatsoever how anyone can apply 
it with 
> the syringe,
> pressing the plunger by hand.
> Impossible if you ask me.


Since it is supposed to be refrigerated and has a short shelf life, 
it may have gotten warm, or it may be old.

Doesn't mean you can't use it, just that it will not be as easy to 
apply.

Dave

On Thu, 06 May 2004 01:30:48 -0000, Dave Mucha <dave_mucha@...> 
wrote:

> --- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan
> <stefan_trethan@g...> wrote:
>> just got the ebay syringe of solder paste...
>>
>> looks ok so far but i have no idea whatsoever how anyone can apply
> it with
>> the syringe,
>> pressing the plunger by hand.
>> Impossible if you ask me.
>
>
> Since it is supposed to be refrigerated and has a short shelf life,
> it may have gotten warm, or it may be old.
>
> Doesn't mean you can't use it, just that it will not be as easy to
> apply.
>
> Dave


I'm not sure about the refigerator thing.
In the school i used the pneumatic dispenser it was at room temp all the 
time.
No problems whatsoever. I know there is "no refrigerator" paste but i 
don't think
they bought it.

ST

If you see solder paste under a microscope it a bunch of 
solder balls a few thousands of an inch in size. 
My guess for needing the refrigeration is to keep flux viscous enough
to keep the solder balls from settling and squeezing out the flux 
in between.

--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan
<stefan_trethan@g...> wrote:
> On Thu, 06 May 2004 01:30:48 -0000, Dave Mucha <dave_mucha@y...> 
> wrote:
> 
> > --- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan
> > <stefan_trethan@g...> wrote:
> >> just got the ebay syringe of solder paste...
> >>
> >> looks ok so far but i have no idea whatsoever how anyone can
apply
> > it with
> >> the syringe,
> >> pressing the plunger by hand.
> >> Impossible if you ask me.
> >
> >
> > Since it is supposed to be refrigerated and has a short shelf
life,
> > it may have gotten warm, or it may be old.
> >
> > Doesn't mean you can't use it, just that it will not be as easy to
> > apply.
> >
> > Dave
> 
> 
> I'm not sure about the refigerator thing.
> In the school i used the pneumatic dispenser it was at room temp all
the 
> time.
> No problems whatsoever. I know there is "no refrigerator" paste but
i 

> don't think
> they bought it.
> 
> ST

--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan 
<stefan_trethan@g...> wrote:
> On Thu, 06 May 2004 01:30:48 -0000, Dave Mucha <dave_mucha@y...> 
> wrote:
> 
> > --- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan
> > <stefan_trethan@g...> wrote:
> >> just got the ebay syringe of solder paste...
> >>
> >> looks ok so far but i have no idea whatsoever how anyone can 
apply
> > it with
> >> the syringe,
> >> pressing the plunger by hand.
> >> Impossible if you ask me.
> >
> >
> > Since it is supposed to be refrigerated and has a short shelf 
life,
> > it may have gotten warm, or it may be old.
> >
> > Doesn't mean you can't use it, just that it will not be as easy to
> > apply.
> >
> > Dave
> 
> 
> I'm not sure about the refigerator thing.
> In the school i used the pneumatic dispenser it was at room temp 
all the 
> time.
> No problems whatsoever. I know there is "no refrigerator" paste but 
i 
> don't think
> they bought it.
> 
> ST


I have not dealt with much solder paste, and then only the 
refregerated kind.

The symptoms seemed similar to something that is dried a little. Hard 
to expel and then goes in a large section.

I'll check out more on solder paste to see what styles it comes in.  

I was looking at the thin ribbons of solder from RadioShack.  they 
claim to solder with a match.  Not sure if one could just lay a thin 
strip over pads, then put the chip on the strip and put the whole she-
bang into the oven.

Dave

On Thu, 06 May 2004 15:42:48 -0000, javaguy11111 <javaguy11111@...> 
wrote:

> If you see solder paste under a microscope it a bunch of
> solder balls a few thousands of an inch in size.
> My guess for needing the refrigeration is to keep flux viscous enough
> to keep the solder balls from settling and squeezing out the flux
> in between.
>


seems to make sense...

Do you think it would be possible to see if a paste is good or bad?

ST

--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan 
<stefan_trethan@g...> wrote:
> On Thu, 06 May 2004 15:42:48 -0000, javaguy11111 
<javaguy11111@y...> 
> wrote:
> 
> > If you see solder paste under a microscope it a bunch of
> > solder balls a few thousands of an inch in size.
> > My guess for needing the refrigeration is to keep flux viscous 
enough
> > to keep the solder balls from settling and squeezing out the flux
> > in between.
> >
> 
> 
> seems to make sense...
> 
> Do you think it would be possible to see if a paste is good or bad?
> 
> ST

I'm not entirely sure the paste actually goes bad.  I think the gel 
part gets thicker and it is just harder to spread.

the real test is to heat it and see if it solders properly.

Dave

>
> I'm not entirely sure the paste actually goes bad.  I think the gel
> part gets thicker and it is just harder to spread.
>
> the real test is to heat it and see if it solders properly.
>
> Dave
>

soldering properly it does...
maybe tomorrow i have time to put together the pneumatic dispenser,
i think i have all needed parts at hand.

ST

--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan 
<stefan_trethan@g...> wrote:
> 
> >
> > I'm not entirely sure the paste actually goes bad.  I think the 
gel
> > part gets thicker and it is just harder to spread.
> >
> > the real test is to heat it and see if it solders properly.
> >
> > Dave
> >
> 
> soldering properly it does...
> maybe tomorrow i have time to put together the pneumatic dispenser,
> i think i have all needed parts at hand.
> 
> ST

Camera... you have a camera right ?

Dave

--- In Homebrew_PCBs@yahoogroups.com, "Dave Mucha" <dave_mucha@y...>
wrote:
> --- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan 
> <stefan_trethan@g...> wrote:
> > On Thu, 06 May 2004 15:42:48 -0000, javaguy11111 
> <javaguy11111@y...> 
> > wrote:
> > 
> > > If you see solder paste under a microscope it a bunch of
> > > solder balls a few thousands of an inch in size.
> > > My guess for needing the refrigeration is to keep flux viscous 
> enough
> > > to keep the solder balls from settling and squeezing out the
flux
> > > in between.
> > >
> > 
> > 
> > seems to make sense...
> > 
> > Do you think it would be possible to see if a paste is good or
bad?
> > 
> > ST
> 
> I'm not entirely sure the paste actually goes bad.  I think the gel 
> part gets thicker and it is just harder to spread.
> 
> the real test is to heat it and see if it solders properly.
> 
> Dave

My guess is the solder itself has not changed and would probably melt
if it can get out of the syringe. I think the problem may be if the
ratio of solder to flux gets changed, then the overall quality of the
 solder joint is affected. Probably not enough flux present to allow
good cleaning and wetting. May not be a big deal for a few hobbyist
boards, but would be a big deal in mass production environment.

What usually happens when I have problems is that I will have paste
coming out, then only flux, then nothing at all. I was getting a lot
of that in my year old paste, but I just squeezed out about an eight
of the tube and the problem went away. Whether that was happening
because of settling of the solder, thickening of the flux  or
something else is hard to say.

> Camera... you have a camera right ?
>
> Dave


Camera? i have a camera? no, wrong.

I only have this JUNK of a webcam which should have 640x480,
in fact has only 100x100 or so and the rest filled with "noise".

I'll see what i can do.

ST