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Electrolytic Cap Placement & Solder

Electrolytic Cap Placement & Solder

1999-11-21 by Elhardt@xxx.xxx

I'm stuffing compenents in all my boards for the first pass solder/wash.  I 
normally mount electrolytic capacitors firmly up against the PCB.  After 
reading about the problems of organic flux residue, I am wondering how I am 
going to clean under under them.  Does it matter if I can't clean under them? 
 Or do I need to keep a centimeter or so space, so I can clean?  Thanks for 
any help.

BTW, this business of having to wash boards within 2 hours of soldering is 
seriously screwing up my assembly line building techniques.  Is the only 
reason we are not using good old rosin core 63/37 solder because it leaves 
unsightly flux marks?

-Elhardt

Re: Electrolytic Cap Placement & Solder

1999-11-21 by Paul Schreiber

>
> I'm stuffing compenents in all my boards for the first pass solder/wash.
I
> normally mount electrolytic capacitors firmly up against the PCB.  After
> reading about the problems of organic flux residue, I am wondering how I
am
> going to clean under under them.  Does it matter if I can't clean under
them?
>  Or do I need to keep a centimeter or so space, so I can clean

Actually, the hole spacing is about 0.025 *wider* then 'spec' to make the
caps "stand up"
off the pcb about 1/32" so the water will flow under there. Note the "yellow
box caps"
have small cutouts for this purpose.


> Is the only  reason we are not using good old rosin core 63/37 solder
because it leaves
> unsightly flux marks?

There are two reasons MOTM does not use rosin core solder (in fact, no one
has used rosin-core solder
*in mass production* since about 1990).

#1 - rosin is designed to *attract moisture* (think of the rosin bag in
baseball, and in gymnastics). Attracting
moisture in *NOT* what we want in synths! Especially VCOs.

#2 - in order to *remove* the rosin off the boards, you need *horribly
messy* chemicals. Freon was the older
choice. There are spray cans of non-CFC rosin flux remover, but my
experience is that this makes a huge
mess because all you do is dissolve the flux and coat the whole pcb with it!
In production lines in the '70s/'80s
there were massive, high-power water jets that 'scrubbed' the flux off with
150 psi water nozzels after a good old Freon
bath (the boards were actually immersed in liquid Freon).

Today, *all* soldering is using "No Clean" flux.

So, a fair question is :"Why not use No Clean everywhere?"

The answer is that I felt that No Clean is harder to solder, and that
organic *still* has the best overall
joint construction. The only reason No Clean replaced organic is that the
manufacturers saved millions
of dollars on water bills (and floor space!).

Paul S.

Re: Electrolytic Cap Placement & Solder

1999-11-21 by Elhardt@xxx.xxx

(Paul Schreiber) writes:
>>Actually, the hole spacing is about 0.025 *wider* then 'spec' to make the 
caps "stand up" off the pcb about 1/32" so the water will flow under there. 
Note the "yellow box caps" have small cutouts for this purpose.<<

Thanks for the info.  Since I haven't yet soldered with organic flux solder, 
I didn't know the residue came off so easily.  I thought it required some 
persistent scrubbing.

As far as solder goes, I forgot about the moisture problem, and I had no 
intention of cleaning the rosin off.  I don't like the toothpaste consistancy 
of no-clean, but maybe I should learn to like it.  It could save me a good 
chunk of time.  Or perhaps it's time for a wave solder machine.

-Elhardt

Re: Electrolytic Cap Placement & Solder

1999-11-21 by Paul Schreiber

Organic flux is actually a mild version of vinegar. I just use warm water
and barely scrub the board for maybe 5 seconds per side.

Paul S.

----- Original Message -----
From: <Elhardt@...>
To: <motm@onelist.com>
Sent: Saturday, November 20, 1999 8:59 PM
Subject: Re: [motm] Electrolytic Cap Placement & Solder


> From: Elhardt@...
>
> (Paul Schreiber) writes:
> >>Actually, the hole spacing is about 0.025 *wider* then 'spec' to make
the
> caps "stand up" off the pcb about 1/32" so the water will flow under
there.
> Note the "yellow box caps" have small cutouts for this purpose.<<
>
> Thanks for the info.  Since I haven't yet soldered with organic flux
solder,
> I didn't know the residue came off so easily.  I thought it required some
> persistent scrubbing.
>
> As far as solder goes, I forgot about the moisture problem, and I had no
> intention of cleaning the rosin off.  I don't like the toothpaste
consistancy
Show quoted textHide quoted text
> of no-clean, but maybe I should learn to like it.  It could save me a good
> chunk of time.  Or perhaps it's time for a wave solder machine.
>
> -Elhardt
>
> >

Re: Electrolytic Cap Placement & Solder

1999-11-21 by Paul Schreiber

Kester Flux #331, 0.020 diameter. I buy it from Allied.

Paul S.

----- Original Message -----
From: J. Larry Hendry <jlarryh@...>
To: <motm@onelist.com>
Sent: Saturday, November 20, 1999 11:31 PM
Subject: Re: [motm] Electrolytic Cap Placement & Solder


> From: "J. Larry Hendry" <jlarryh@...>
>
> Speaking of solder.....  Paul what solder do you buy for "organic?"  Since
> I know you are Mr. Mouser, I bet you have a Mouser page number or part
> number for it.
>
> Thanks,
> LH
>
>
> > From: "Paul Schreiber" <synth1@...>
> >
> > There are two reasons MOTM does not use rosin core solder (in fact, no
> one
> > has used rosin-core solder
> > *in mass production* since about 1990).
> >
> > #1 - rosin is designed to *attract moisture* (think of the rosin bag in
> > baseball, and in gymnastics). Attracting
> > moisture in *NOT* what we want in synths! Especially VCOs.
> >
> > #2 - in order to *remove* the rosin off the boards, you need *horribly
> > messy* chemicals. Freon was the older
> > choice. There are spray cans of non-CFC rosin flux remover, but my
> > experience is that this makes a huge
> > mess because all you do is dissolve the flux and coat the whole pcb with
> it!
> > In production lines in the '70s/'80s
> > there were massive, high-power water jets that 'scrubbed' the flux off
> with
> > 150 psi water nozzels after a good old Freon
> > bath (the boards were actually immersed in liquid Freon).
> >
> > Today, *all* soldering is using "No Clean" flux.
> >
> > So, a fair question is :"Why not use No Clean everywhere?"
> >
> > The answer is that I felt that No Clean is harder to solder, and that
> > organic *still* has the best overall
> > joint construction. The only reason No Clean replaced organic is that
the
Show quoted textHide quoted text
> > manufacturers saved millions
> > of dollars on water bills (and floor space!).
> >
> > Paul S.
>
> >

Re: Electrolytic Cap Placement & Solder

1999-11-21 by J. Larry Hendry

Speaking of solder.....  Paul what solder do you buy for "organic?"  Since
I know you are Mr. Mouser, I bet you have a Mouser page number or part
number for it.

Thanks,
LH


> From: "Paul Schreiber" <synth1@...>
> 
> There are two reasons MOTM does not use rosin core solder (in fact, no
one
> has used rosin-core solder
> *in mass production* since about 1990).
> 
> #1 - rosin is designed to *attract moisture* (think of the rosin bag in
> baseball, and in gymnastics). Attracting
> moisture in *NOT* what we want in synths! Especially VCOs.
> 
> #2 - in order to *remove* the rosin off the boards, you need *horribly
> messy* chemicals. Freon was the older
> choice. There are spray cans of non-CFC rosin flux remover, but my
> experience is that this makes a huge
> mess because all you do is dissolve the flux and coat the whole pcb with
it!
> In production lines in the '70s/'80s
> there were massive, high-power water jets that 'scrubbed' the flux off
with
Show quoted textHide quoted text
> 150 psi water nozzels after a good old Freon
> bath (the boards were actually immersed in liquid Freon).
> 
> Today, *all* soldering is using "No Clean" flux.
> 
> So, a fair question is :"Why not use No Clean everywhere?"
> 
> The answer is that I felt that No Clean is harder to solder, and that
> organic *still* has the best overall
> joint construction. The only reason No Clean replaced organic is that the
> manufacturers saved millions
> of dollars on water bills (and floor space!).
> 
> Paul S.

Re: Electrolytic Cap Placement & Solder

1999-11-21 by Christopher Jeris

> There are spray cans of non-CFC rosin flux remover, but my
> experience is that this makes a huge
> mess because all you do is dissolve the flux and coat the whole pcb with it!

Laugh at me, but I did this -- a PAiA midi2cv8 was the first kit I built
after my first few MOTM modules, and it didn't come with solder.  I made
the mistake of buying rosin core (not yet understanding the differences
between solder types) and then had to get it all off.  First I tried to
use isopropanol moistened cotton balls.  Great, now I have bits of
rosin-sticky cotton fluff all over my pcb!  Finally I had to fill a pie
pan with the alcohol, dunk the board and scrub it with the trusty "Flux
Remover" toenail brush.  20 minutes each side, refilling when too much
alcohol evaporated ... and the board is _still_ sticky in places.  Sigh.
That's how I learned not to use rosin core on pcbs.

(Speaking of toenail implements, has anyone else tried a big sturdy
toenail clipper for snipping leads?  I may be crazy but I think it works
_much_ better than diagonal cutters.)

peace,
Chris Jeris

Re: Electrolytic Cap Placement & Solder

1999-11-23 by Hugo Haesaert

Hi All !

That no-clean solder "wet's" a bit harder, i think it has to do with 
the flux used, but i've experienced no "tooth-paste" effects . This 
with an unregulated iron .  Since a good week i'm using a kit-built 
electronic soldering station, and get similar results to the organic 
and rosin solder, with the temperature 20C higher .  At this temp the 
organic and rosin solders splatter more .  That no clean solder still 
leaves a deposit, but i gather that this is inoffensive .

Not all rosin solders are the same .  I still got some that resulted 
in a brown molasses-like crust .  Here in europe it is almost 
impossible to find anything else than rosin based solder in shops .
(But my stock of no-clean is growing ;-) )

Another thing is that double sided boards "take" more solder than 
single sided .  Hence more flux remains .

Vinegar is acetic acid, afaik always liquid .  Probably still got 
lung damage from the years passed poring over the infamous "stop-
bath" used in B-W chemical photography .  I believe nowadays citric 
acid or potassium-bromide is used here .  Citric acid is available in 
cristallline form, so could be used in solder .  But there are many 
more compounds around .  It's anybody's guess what they are actually 
using .  The smoke it gives off is no less irritating than the rosin 
fumes, imo, but the smell is different :)

Freons are good products with the unfortunate property of destroying 
the ozone layer .  They are rightly banned from most applications, 
and production has stopped afaik .  The airliner industry still uses 
halon fire extinguishing systems, as they are still the best way to 
put out a fire .  And they are not poisonous when inhaled .  
Releasing massive amounts of co2, as normal for electrical fires, in 
the confines of that pressurised cigar-tube is just not on :) . The 
freons used here are religiously recuperated and recycled, at great 
cost .  In the "cold" industry replacements are used that are similar 
but less reactive .

I assemble my boards in 3 layers, depending on the height of the 
components .  Recently i got an assembling frame that can hold the 
board at 3 different depths (4 euro cards/MOTM boards at once, if 
needed) . One closes a foam lined lid over the parts, flips over the 
frame and the soldering fest can begin :)  No splaying of leads to 
hold the components .  Still, i only solder one lead per component at 
first, then inspect and adjust, then the rest of the pins .  Before 
the frame i used a diy version of this procedure .

Haa, nothing like a vacation to write long emails :)  Off to the next 
module .

Bye for now .


Keep 'em oscillating :)


Hugo
=

Re: Electrolytic Cap Placement & Solder

1999-11-24 by JWBarlow@xxx.xxx

In a message dated 11/21/99 10:16:27 AM, cjeris@... writes:

>(Speaking of toenail implements, has anyone else tried a big sturdy
>toenail clipper for snipping leads?  I may be crazy but I think it works
>_much_ better than diagonal cutters.)
>

I used to use these, but had too many instances when I actually cut (broke?) 
the joint off which I'd assumed was due to the clippers getting dull. Since 
then, I just use those tiny diagonal cutters (which work great) but I often 
think about getting those bent nose cutters designed for this purpose.

JB
Hey! How bad is to use the old Kester 44 without defluxing -- not MOTM but 
general circuits (bad, not good, great)? The only time I've seen a problem is 
around hot areas on boards (after a long time) where the flux has really 
flowed around other components.

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