[Elecraft] Soldering and Heat Damage ?

[Don Wilhelm]

Phil,

To amplify what Bill W4ZV said, you are not likely to have a heat 
problem with a 700 deg F temperature controlled soldering station.
That assumes that you use a tip with adequate heat mass to conduct heat 
to the solder connection.  I personally prefer a 3/32 inch screwdriver 
tip over a conical tip because the larger surface of the screwdriver tip 
will conduct heat to the solder connection more quickly.  Note that this 
is my personal preference, many have good success with the conical tips.

Remember that it takes a combination of time coupled with high 
temperature to damage components.  You are more likely to create damage 
with too low a temperature applied for a long time than with a higher 
temperature applied for a short time.  Watch the solder and check the 
time it takes for the solder to flow out onto both the solder pad and 
the component lead to an almost invisible edge -if it flows out in less 
than 2 seconds, the iron temperature is too high, but if it takes longer 
than 3 seconds, the temperature is too low.  Since the iron dwell time 
depends on the size of the solder pad and the size of the component lead 
(larger copper areas will conduct heat away from the connection), you 
may find you have to increase the heat or switch to a larger solder tip 
when soldering things larger than the average component lead and solder pad.

Another related point for those who are accoustomed to soldering onto 
lugs and other "old Heathkit" items, the Elecraft boards have 
thru-plated solder pads, and it is sufficient only to fill the hole with 
solder - I actually prefer to have a very small fillet of solder, but it 
is easy to use too much solder and end up with a big blob on the board.  
To more easily control the amount of solder applied, use a small 
diameter solder - I normally use 0.15 inch, but 0.20 inch diameter will 
do with care - I cannot recommend larger solders than .020 inch although 
many others say 0.25 inch is OK.

73,
Don W3FPR

Phil Hystad wrote:
> Back when I was a kid and doing a lot of experimenting, I would sometimes build a transistor based project.  I was comfortable with tube circuits but never with anything solid state.  One fear I had was destroying transistors with heat from a soldering iron.  I was taught to always use a heat sink on the leads between the soldering point and the device to protect the transistor or diode from the heat.
>
> Then, I left electronics and experimentation.  I have this big gap dating between 1967 and 2008.  In 2008 I built my first kit since those days of the early to mid 1960s.  In building this kit, the parts were all to be mounted on PCB with virtually ZERO room to connect any heat sink.  I used a very nice temperature controlled soldering iron with a recommended pencil style tip.  The result was that the kit worked (a small audio oscillator and amplifier).  But, I was fearful that I was toasting my transistors and the two ICs that were part of this kit.
>
> I have read several soldering notes, including the one on Elecraft, and they do not specifically mention heat damage to components and what you need to do to avoid that sort of thing.  They may hint at it though by recommending the temperature controlled soldering irons and things of that ilk.
>
> So, how much danger is there in destroying ICs, transistors, and such with a soldering iron applying such components to a PCB or maybe even using some kind of ugly construction?
>   
>