Let's Make Robots!

Soldering iron not hot enough?

I've got a really crappy soldering iron so that very well could be the cause of my problem, but I want to be sure before I head to Radio Shack and drop some cash.  See, I know that you're supposed to heat the connection and then apply the solder onto the joint, rather than putting the solder directly on the iron and letting it melt.  But when I use the correct method, the joint doesn't get hot enough for the solder to melt!  Even if I let the iron sit there for 15 seconds, the solder refuses to liquify unless it directly touches the iron.  I'm tinning the iron and doing everything right as far as I know.  Is this a problem with my soldering iron, or am I just missing something? 

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.
well done, good job
I feel as though I've taken my first step into a much larger world ...

Woohoo!  I took care of all the shorts and re-soldered a few parts, and my circuit board is working now!  It's really exciting for me since this is the first time I've built a circuit off of a breadboard.  :D

In all its glory:

 Woohoo!

This circuit board is a basic 555 astable setup.  It will blink the LED "eyes" on my first robot.  Now I've got to get to work on the other circuit board which will be the robot's "brain." 

Try adding more solder to the iron before touching the component with it. You do need some solder on the iron to act as the heat conductor to the component. Try with heaps (like a big blob) on the iron to start with, see how you go, then try using less each time.

The reason you need to put the solder on the component rather than the iron is mainly so that you get enough flux to help the solder flow. And on flux, make sure the solder you are using actually has flux in it, do you see smoke come off the tip when you add more solder? When the smoke it gone, so is the flux.

Well ... soldering the components in place didn't go so well.  The LED isn't blinking and I think it's because I have a short circuit.

 Aaaarrrrgggg

You might be able to make out the scraping marks where I was attempting to separate the short circuits.  I think it's also possible, though, that while I was soldering I overheated one of the components and it's not working now.  Probably the IC or the capacitor. 

If it melts the solder on the tip, then it should be hot enough....but it might be the angle that you're holding the soldering iron at that isn't giving it enough contact. Have you tried putting the solder against the joint and putting the iron tip against that to melt it against the point you want to solder? I've used that among other techniques...

 if you're on the part for 15 seconds, thats not good, it could damage certain parts and usually melts plastic....

If you get a RS special, get the 20/40watt(switchable) iron with the power switch on the base. I ended up getting one of those(free!!) and really liked it. they aren't super expensive and are great for starters. The plain wired ones aren't worth getting imo.

Hmm, ok I'll consider that iron.

The problem with just melting the solder, though, is that I hear that doesn't make a strong connection.  The components have to be hot in order for them to truly adhere to the solder.

It could be the angle, possibly.  I'll experiment with that. 

True that both have to be hot, but you'll see it happen and sometimes it helps to get things started this way. After soldering enough things you'll find what works and what doesn't work for specific components. Thicker peg legs like power posts would need to have more contact with the iron to get a good joint, but things like caps and resistors should be pretty quick. I'd practive with various components if you have the means to, try soldering and desoldering them. And yeah try different angles. The tips I've used have a 25-45 degree angle at the tip, getting the surface contact with most of that is usually key to getting the joint hot fast. I've also used flat tips which seeped to take a shorter time but not always very good with small components.

edit: I'll see if I can get some pics of the tips that I've used.

 

Thanks for all the advice.  I've literally got my computer on one side of the desk and my soldering station on the other.  So I'm slowly working on this circuit board as I learn more.  :)

This is basically a practice run.  It's one of two circuit boards for my first robot, Blinky, and it's the less important of the two (it's just a 555 IC and a few components that will function as a way to make the LED eyes "blink"). 

What is the wattage of the iron?