Source of poor solder joints?

[Darwin, Keith]

Looks like poor soldering joints is the #1 problem with rigs we build.
While building my KSB2 I was wondering about and came up with an idea.
 
I wonder if many poor solder joints occur because of the lead moving as
the soldering tip is removed.  In the case of an IC, while I'm applying
heat, I'm pushing against the chip's lead.  When I remove the soldering
iron, the lead is going to spring back just a bit (i.e. move) as the
solder connection is cooling.  Could this be a major contributor to poor
solder joints?
 
- Keith N1AS -
- K2 5411.ssb -
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[zeke7237]

Nahhh .. assuming you're using adequate heat, the solder hasn't set up
yet. The time elapsed between the tip pulling away and whatever
mechanical stress relief might happen would be very short, a few
milliseconds ...

$.02 de w1rt/john

On 11/22/06, Darwin, Keith <[hidden email]> wrote:

> Looks like poor soldering joints is the #1 problem with rigs we build.
> While building my KSB2 I was wondering about and came up with an idea.
>
> I wonder if many poor solder joints occur because of the lead moving as
> the soldering tip is removed.  In the case of an IC, while I'm applying
> heat, I'm pushing against the chip's lead.  When I remove the soldering
> iron, the lead is going to spring back just a bit (i.e. move) as the
> solder connection is cooling.  Could this be a major contributor to poor
> solder joints?
>
> - Keith N1AS -
> - K2 5411.ssb -
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
>  http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Don Wilhelm-3]

Kieth,

Very likely IMHO.  Cold solder joints will look gray because of the
fractures.

That is exactly the reason I recommend a eutectic solder (63/37 alloy)
rather than the 'standard' 60/40 stuff.  There is no plastic state with the
eutectic alloy.

73,
Don W3FPR

> -----Original Message-----
>
> Looks like poor soldering joints is the #1 problem with rigs we build.
> While building my KSB2 I was wondering about and came up with an idea.
>
> I wonder if many poor solder joints occur because of the lead moving as
> the soldering tip is removed.  In the case of an IC, while I'm applying
> heat, I'm pushing against the chip's lead.  When I remove the soldering
> iron, the lead is going to spring back just a bit (i.e. move) as the
> solder connection is cooling.  Could this be a major contributor to poor
> solder joints?
>
> - Keith N1AS -
> - K2 5411.ssb -
>

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Craig Miller-5]

I agree with Don.  Just the smallest, un-noticable motion of the joint while
the solder is solidifying can produce a cold solder joint.  That's why I
always re-flow the connections that were done first to hold a component in
place, like the corner pins on an ic.  In fact, I often will go back and
re-flow all the connections on a device after things have cooled off
completely.  It means taking twice as long to do the soldering but that's no
problem because with an Elecraft kit the building process is at least half
the fun.

Craig Miller
K3OOL
K2/100 4790
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Tom Hammond-3]

Hi Keith:

In my limited experience, most poorly soldered joints come from:
  (not necessarily in order of importance)

  1) applying to little heat,
  2) applying ample heat, but not for long enough to allow the
     solder to 'flow' properly,
  3) applying too little solder

If ample heat was properly applied, AND for an adequate length of time,
merely removing the tip of the iron from the soldered joint should
leave more than ample residual heat to allow the joint to properly
solidify.

I've seen 'newbie' builders 'peck' at the joint being soldered with
their soldering iron tip, rather than leaving it in one spot long
enough for the heat to be transferred to the pad wire and solder.
They'll 'warm' up the joint... melt a bit of solder onto the tip of
the iron and then 'dab' at the joint, instead of applying enough for
the solder to FLOW onto and throughout the components of the connection.
This is most often evidenced by looking at the joint thru a magnifier.
You can readily see that 1) the solder never 'flowed' in and around the
joint, 2) often there's NO SOLDER inside the plated-thru hole at all,
just a small 'blob' on one side of the PC board pad, and possible a bit
on the wire lead.

'Cold joints' resulting from the builder's having accidently moved the
component lead after the heat's been removed are much less frequent
than poorly soldered joints from the two above causes.

Take yer time, folks... this is NOT a race... apply the heat long enough
that the solder will flow smoothly, AND apply at least enough that the
solder flows down and INTO the hole of the plated-thru connection.

73,

Tom Hammond    N0SS

At 07:45 AM 11/22/2006, Darwin, Keith wrote:
>Looks like poor soldering joints is the #1 problem with rigs we build.
>While building my KSB2 I was wondering about and came up with an idea.
>
>I wonder if many poor solder joints occur because of the lead moving as
>the soldering tip is removed.  In the case of an IC, while I'm applying
>heat, I'm pushing against the chip's lead.  When I remove the soldering
>iron, the lead is going to spring back just a bit (i.e. move) as the
>solder connection is cooling.  Could this be a major contributor to poor
>solder joints?

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Ron Hahn (EI2JP)]

Colleagues,

In keeping with this thread I wonder if the tools used are as much at  
fault as the technique?

I use a Weller WTCPN station with 60/40 solder and a fine tip, and  
find that the plated tips seem to "lose" their tinning and have to be  
swiped through the sponge and a bit of solder applied.

Given that time has moved on is there a better, moderately-priced  
instrument available for this type of construction?  230v of course ;-)

 From my own experience I've found that the eyes aren't what they  
used to be and I too find myself going over joints.  Having recently  
invested in an illuminated magnifier lamp I find I don't have to do  
this as much as I used to, but its still a problem.  Is our aging  
profile in the hobby also contributing to this?

Ron
-
Ron Hahn - EI2JP
Grid:  IO62TG  CQ: 14  ITU: 27  IOTA: EU-115
FISTS: 10883 QRP-ARCI: 12584 G-QRP: 11968
Club Web Site:  http://www.ei1karg.com
QSL Info: http://www.qrz.com/detail/EI2JP
Keeper, EI7KYR
Mob. [phone]



_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Tom Hammond-3]

Hi Ron:

>In keeping with this thread I wonder if the tools used are as much at
>fault as the technique?
>
>I use a Weller WTCPN station with 60/40 solder and a fine tip, and
>find that the plated tips seem to "lose" their tinning and have to be
>swiped through the sponge and a bit of solder applied.

As a matter of procedure, I 'swipe' the tip of my iron every time I
pick it up to solder a joint... though I may solder several
connections in a single pass (e.g. an IC). I don't use a sponge,
however. I use a 'curly' stainless steel kitchen pot 'scrubbie' and
need only to plunge the tip down into the scrubbie to clean it off
without losing any of the tip temp to the moisture of a damp sponge.
See: http://www.n0ss.net/soldering_iron_tip_cleaner.pdf

>Given that time has moved on is there a better, moderately-priced
>instrument available for this type of construction?  230v of course ;-)

Though I personally prefer the Hakko 936-x series of T/C irons, I
can't think of a single reason that the WTCPN should be entirely
adequate for the job.

> From my own experience I've found that the eyes aren't what they
>used to be and I too find myself going over joints.  Having recently
>invested in an illuminated magnifier lamp I find I don't have to do
>this as much as I used to, but its still a problem.  Is our aging
>profile in the hobby also contributing to this?

To some extend... IF we don't recognize where a little 'help' can be
used to our advantage, it probably is.

Cheers,

Tom   N0SS

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[stephen Farthing]

======================== snip
I don't use a sponge,
however. I use a 'curly' stainless steel kitchen pot 'scrubbie' and
need only to plunge the tip down into the scrubbie to clean it off
without losing any of the tip temp to the moisture of a damp sponge.
=========================

FWIW Maplins (the uk equivalent of radioshack) sell a commercial equivalent
Based on recycled brass swarf. Anyone with access to a lathe cold easily
turn one up.

Regards

Steve G0XAR

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Stuart Rohre]

Wiping the tip (clean iron tip, well tinned) before each joint is made when
doing pads and wetting the tip with the tip of the wire solder are key
steps.  Touch the tip with fresh solder just before starting to solder the
joint.  Apply the solder wire to the junction of the lead, pad, and iron
tip. Hold steady until you see full wetting action, then get the heated tip
off the joint in a smooth motion.

Also, use smaller diameter solder when you are doing just a pin of a active
IC/ transistor, larger solder when doing shield can soldering, etc.  Make
the solder fit the work.

Proper heat and tip size has been mentioned.  A high intensity light for
older eyes and a lighted magnifier make inspection of each joint a faster
process.  The light helps insure you got solder all around a pad, wire lead,
device lead, etc.

Practice with a heat controlled iron, or a smaller constant wattage iron,
makes perfect solder joints.  Inspection though, is still needed just in
case you get in a hurry.  Check the tightness of your element and tip before
you fire up the iron.

Stop working when you are tired, or eyesight gets fuzzy.  Don't rush an
assembly job.

Check off each step, read it first, understand before you do anything.
Double check that you have the right value part, check off each step after
inspecting the joints and the parts used in that step.

Read the manuals through before starting a kit.  Clarify any unclear points.
This forum is very helpful as there are a lot of experienced builders of the
same units here as the one you may be assembling.

GL and 73,
Stuart
K5KVH


_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Stuart Rohre]

You should not be pushing the iron against the IC lead so hard it springs at
all.

For ICs, usually you spring the leads open a bit more than factory out of
package, and they hold themselves in the board.  You spread component leads
to hold themselves into pads or hold the component with a finger tip of one
hand while applying soldering iron with other.  Sometimes, I have to wrap a
coil of solder on a finger, so I can use one hand to both hold the
component, with one finger, and another finger applies the solder wire where
it should go.  It takes some practice, but if you have had adequate sleep
and steady hand, then it can be done.

When my hands are less steady, I use my magnifier stand with clips to hold
the board in such a way that gravity might assist in steadying the component
and its leads.  That may mean the board is vertical and you have to apply
the solder and iron from one side.

But, bending the component leads, or taking advantage of the crimp in some
leads may be all you need do.

Stuart
K5KVH


_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Ben Hofmann K1NT]

I'm currently building a KPA100, and have noticed on several joints after I apply the solder, and then remove the iron, the solder bubbles around the lead, and then usually the solder joint looks bad.  What is happening here?  I don't recall this happening when I was building the base K2, but it's been quite a while.

-Ben  K1NT


_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Don Wilhelm-3]

Ben,

Good eyes - keep looking at your soldering that way.
The bubbling is the result of flux trapped inside the solder boiling.  It is
also an indication that your soldering temperature is a bit too low - the
joint definitely did not receive adequate heating.
Yes, such behavior will result in a bad solder connection.

73,
Don W3FPR

> -----Original Message-----
>
> I'm currently building a KPA100, and have noticed on several
> joints after I apply the solder, and then remove the iron, the
> solder bubbles around the lead, and then usually the solder joint
> looks bad.  What is happening here?  I don't recall this
> happening when I was building the base K2, but it's been quite a while.
>
> -Ben  K1NT
>

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Ben Hofmann K1NT]

I wonder why it only happens once I remove the iron?  Seems to me, a boiling action would cause bubbling while the heat is being applied.  Unless solder has some kind of "skin" like water has, and removing the iron breaks the "skin" at which point the bubbles could escape?

-Ben  K1NT

Don Wilhelm <[hidden email]> wrote: Ben,

Good eyes - keep looking at your soldering that way.
The bubbling is the result of flux trapped inside the solder boiling.  It is
also an indication that your soldering temperature is a bit too low - the
joint definitely did not receive adequate heating.
Yes, such behavior will result in a bad solder connection.

73,
Don W3FPR

> -----Original Message-----
>
> I'm currently building a KPA100, and have noticed on several
> joints after I apply the solder, and then remove the iron, the
> solder bubbles around the lead, and then usually the solder joint
> looks bad.  What is happening here?  I don't recall this
> happening when I was building the base K2, but it's been quite a while.
>
> -Ben  K1NT
>

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Chris Kantarjiev K6DBG]

In addition to all the great advice about soldering, I'd like
to add my two cents: holding the item to be soldered, and
the solder, and the board, and the iron, is a neat trick.

In the "real world", there are tools to help - PC board vices
with hold downs that help steady the component. In the shack,
the temptation is to "spring" or worse *bend* the component
leads to hold them in place, and then solder with the item
hanging down.

I don't find that acceptable, if only because bent-soldered-trimmed
leads are very difficult to remove.

So over time, I've somehow developed a technique that works
to hold everything in place.

I use a panavise to hold the board, and the board is usually close
to vertical for component loading. I have learned to hold the solder in
my left hand while stabilizing the component on the other side
with the smaller fingers of the same hand - sometimes this means
a long snake of solder from the coil to the solder land. But
works to get the item tacked in place, usually. (It works
great for ICs.) Reposition as needed for esthetics, then
you can move the board to whatever position you like to solder
the rest of the leads, and finally go back to the original one
to add more solder or reflow as needed.

It's sometimes almost comical, but it works...

73 de chris K6DBG
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Jack Smith-6]

In addition to the technique described by Chris, K6DBG, I've found a few
simple household items make a useful holding fixture.

1. A piece of thin, relatively soft foam, perhaps 1/2" thick.
2. A few spring clothespins
3. A piece of backing material, such as part of a scrap PCB or a piece
of aluminum.

Insert the parts through the holes, and lay the foam on the component
side. Place the backing material on top of the foam, making the foam the
filling in the sandwich and the PCB and backing material the bread. Use
spring clothespins to hold the sandwich together. It's important that
you use a clamp arrangement that is not too strong or you will flex the
PCB. An old spring clothespin provides about the correct force in my
experience. A new clothespin is almost too strong.

Flip the PCB over and solder away. As long as you don't poke the
component leads too hard, they will stay in place nicely.

You can see a photograph of this approach at pages 6 & 7 of my Z90
Assembly Manual, on line at
http://www.cliftonlaboratories.com/Documents/Assembly%20Instructions.pdf.

For larger PCBs, I use a longer piece of aluminum backing plate and
larger foam. This approach works best if you start with the small,
close-to-the-board parts first, such as resistors and the taller parts
last. I usually half-a-dozen components at a time, solder and then
proceed to the next group.

The photographs I mentioned are of a 4915 KHz bandpass filter and using
the foam holder, assembly went very fast. I built three dozen of these
with an average assembly time of around 20 minutes each, a good part of
which time was associated with the toroid cores and connectors.

Jack K8ZOA
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com