[Elecraft] Poor soldering (was: Does build quality affectperformance?)

[Don Brown]

Hi

The first problem in soldering is the iron itself. Although a K2 can be 
built with a simple soldering iron the problem with most of them is they get 
too hot to make up for the lack of capacity. These simple irons have 
elements that must reach a reasonable temperature and hold that temperature. 
With out any switching or feed back to regulate the iron they tend to be too 
hot when not being used and too cold when you try to make a joint. A 
soldering station on the other hand has a high capacity heater and a control 
circuit or mechanical switch that can sense the tip temperature and apply 
the correct amount of power to the tip to keep it at the correct 
temperature. I highly recommend buying a temperature controlled soldering 
station.

The next mistake is selecting too cold of a tip temperature. This goes 
against what you would think as you would expect a hot tip would be more 
likely to damage the board but this not the case, within reason. A 700-750 
degree iron will heat the joint quicker and allow you to get on make the 
joint and get off of the board faster than a 600 degree tip. It is the dwell 
time on the board that is more important than the temperature when it comes 
to board damage.

The recommended solder is 60/40 rosin core or better yet 63/37 rosin core 
solder. Multicore or Kester 44 fit these requirements. 0.031 or preferably 
0.025 diameter should be used. Silver solder is NOT recommended because it 
is harder to remove in case of a mistake or rework required to install 
options. If you have some experience soldering then no-clean flux will make 
the board look better but it is harder to make good joints with this solder 
because of the low amount of flux in the core. Of course acid core or water 
soluble solders should never be used and will void the warranty.

As far as technique this takes some experience. Building one or two of the 
mini kits is a good way to start. Every K2-K1-KX1 owner needs a dummy load 
so build the DL1 to practice your soldering. Remember to heat the joint not 
the solder. The joint should be hot enough to melt the solder when the fresh 
solder is applied. Each joint should take about 2-3 seconds to make and the 
iron should be removed. If it does not look good allow a few seconds to cool 
and retouch the iron for 1 or 2 seconds to reflow the joint do not add more 
solder.

One of the other problems is too much solder. Using 0.025 diameter solder 
will help here. The pads are plated through so it is not necessary to fill 
the hole so it comes through to the other side. Just a smooth fillet on the 
bottom of the board is all that is needed. The solder should not be mounded 
up into a ball on the pad.

The something else is tinning toroid leads. This is still the number one 
problem. The wire needs to be tinned all the way up to the core so when the 
wire is pulled tight you are not pulling the insulation down into the pad. 
There are many ways to strip and tin the wires. Just make sure you do a good 
job here and you will avoid many problems.

Don Brown
KD5NDB




----- Original Message ----- 
From: "Craig Rairdin" <craigr at laridian.com>
To: <Elecraft at mailman.qth.net>
Sent: Tuesday, February 28, 2006 10:36 AM
Subject: [Elecraft] Poor soldering (was: Does build quality 
affectperformance?)


> However, since the biggest problem that beginners seem to have is
> poor soldering, sometimes a beginner's rig may have poor joints
> that don't cause problems immediately.

With that in mind, what are the most common soldering problems? Could we
head off errors by discussing them here or beefing up the material on the
Elecraft Web site on this topic?

Is it:

 * Iron too hot/cold
 * Wrong tip
 * Too much heat applied (damaging part or pad)
 * Bad technique
 * Wrong solder
 * Too much/little solder

Or something else?

Depending on what the symptoms of the problems are, this would also help new
owners choose a builder and help purchasers of used units inspect the work
before buying.

When I decided to build a K1 I spent a lot of time reading the material on
the Elecraft Web site, then I bought a suitable solder station rather than
resurrect my old Radio Shack iron. Both my K1 & K2 turned out great with no
problems in checkout, alignment, or everyday operation, but you have me
worried that I might have screwed up in ways I haven't discovered yet. :-)

Craig
NZ0R
K1 #1966
K2/100 #4941