[Lou Erickson]

I've been lurking here for ages, and reading along.  I keep seeing excellent DIY amps and thinking, "I can do that!"  I have been collecting the parts to build some good things, and finally have the time to build them.
 
Knowing I was out of practice, I'm starting with a CMoy.  It's a good thing I'm practicing, because I'm scorching every pad on the perfboard.
 
 
Long ago and far away, I did some DIY electronics.  I even had a class, which included how to solder.  I don't remember having any particular difficulty with it, and successfully built several kits.
 
I don't remember it taking long to make a connection.  The tinned iron rests on both surfaces to be soldered, a moment for them to heat up, and then apply the solder to the component being soldered (not the iron) and add enough to flow over the connection.
 
I feel like these connections are taking a really long time to make.  The solder won't melt against the component or the board, though, unless I keep the iron on it a long time.  By the time solder flows, the board is scorched.
 
Clearly, I'm doing something wrong.  But what?
 

Every time I've built things before, I had a lousy Radio Shack iron - the kind so often derided here.  I managed with one just fine, but the tip was always really big and hard to work with.  As I've collected the components for the projects I want to build, I found a Hakko 936 on sale, and picked it up.
 
Have I got the iron set too cool?  Too hot?  It's set for 300C. 
 
I'm using a Hakko chisel tip.  It's about the same width as the solder pads.  The needle tip the iron came with seemed impossibly small for normal work.  Have I got the wrong tip?
 
What can I change to keep from burning boards?  What have I forgotten or missed?
 
Any advice would be appreciated.  I've got to be doing something wrong here.

 

[Avro_Arrow]

What kind of solder are you using?
 

 

[c12mech]

Do you have the tip of the iron tinned well.  It makes a big difference to me if it is.  I also clean the tip before each joint.  Most times I just touch the solder to the tip before the board.  I believe the heat transfers better with a fresh bit of solder on the tip.  As for the temp, I keep my Weller WLC100 right between the 3 and 4.  I'm not sure what temp it is but it seems to work the best for me. It took a little trial and error before I got it exactly where it works best for me.  If you have extra proto board cut some wire and just practice with different temps until you find one that works for you.

 

[00940]

Do you keep the top of the iron tinned ?
 
http://www.ehow.com/video_4416890_tin-soldering-iron.html
 
edit: someone was faster than I !

 

[tangent]

I don't subscribe to the "melt the solder through the component lead" school. Heating the pad and component lead at the same time is a good idea, but to get the solder flowing, I touch the solder to the iron. As soon as it starts flowing, I move the solder around the pad to give quick, complete coverage.
 
Sometimes I let the iron dwell on the pad a little longer after the pad is completely covered, until the solder stops moving. That ensures that everything has gotten hot enough to make a solid joint.
 
You may want to watch my Basic Soldering Techniques video.

 

[Uncle Erik]

My technique is to put a small solder blob on the tip. Maybe 1mm of solder, give or take. Then I put the blob on the lead/pad and it flows around them very quickly, while I add more solder as this happens. That makes a joint within 3-4 seconds. This has worked very well for me. I haven't had a cold solder or a failure yet.

Also, when working PCBs, I later trim the leads with flush cut clippers, then reflow it for a second or two so it is nice and smooth. Also makes it easier to clean the flux splatters off since a paper towl (usually soaked in denatured alcohol) won't catch and tear on anything jagged.

 

[Rescue Toaster]

First off, as Avro asked, let us know what kind of solder you're using. Lead free can be a hassle. The easiest to use is 63/37 with a rosin activated (kester 44) or mildly activated (kester 285) flux core. 60/40 is acceptible, but there are lots of crazy combinations out there that range from fairly easy to use to almost impossible.
 
Wipe the tip on a clean sponge (the one that came with the iron, not from the grocery store) that's wetted only with distilled water. If the tip turns blue after 2-3 seconds, it's way too hot or has been permanently oxidized. Add some solder to the tip. It should spread out and coat the tip fairly smoothly, and the flux should take a couple seconds to boil away. If the solder beads up and doesn't spread out the tip has dewetted and that would explain the trouble you're having. Tip cleaner can sometimes rescue a dewetted tip but it reduces tip life so it's best to take care of your tips than have to recondition them constantly.
 
For simple through-hole, to minimize time on the pad, place the iron on the joint so it contacts both surfaces (pin and pad), touch the solder wire to the corner of pin/pad/iron so it melts onto the iron and contacts the joint, forming a heat bridge. Then move the wire around to the opposite side of the pin. Molten solder flows towards the heat.

 

[Lou Erickson]

Thanks for all the help, guys.
 
To answer the questions, yes, the iron is tinned and tip nicely prepared.  I'm using a 63/37 lead-based rosin-core solder - first time I've used anything but 60/40, too.
 
Yesterday, after work, I stopped and picked up some solid core wire and cut off a mess of little bits and practiced, getting nowhere.  Then I watched Tangent's video, which helped.  I was getting cold solders quite often, but things were much closer to where they needed to be.
 
Then I got out one of my cheap 15w radio shack irons, and tried it.  No trouble at all with it.  Big tip, though, and awkward to work with.
 
In a flash of insight, I remembered that my meter has a temperature probe.  I could even find it!  I measured the temperature of the RS iron and the temperature of the Hakko.  The RS iron was 60 C hotter.  After turning the heat up on the Hakko, it's working better, too.  It was just hot enough to melt solder, and took forever to get heat on to the board.
 
Combination of technique and temperature.  Both of which I can fix.
 
I have several projects of various complexity in mind, but am starting with a cmoy for practice.  I'm using the suggestions from Tangent's excellent web site, and have the Radio Shack perfboard.  The half that's full of scorch marks is going to be for soldering practice, and I'll build the amp on the other half.  There's plenty of holes on this perfboard to get me back to making proper connections, and then I'll build the amp.
 
I knew y'all would be able to straighten me out!  Thanks for the help; I appreciate it a lot.
 

 

[Rescue Toaster]

Was the Hakko used? The temperature settings on most irons need to be calibrated, so just because it says 300C on the front doesn't mean the tip is anywhere near that. I'm curious to hear what you got on the temp probe.

 

 

[Lou Erickson]

The Hakko was new.  It said it should be calibrated, and I assumed it is; I just didn't know what temperature was best to use.  Setting it closer to that used by the RS iron is working better.
 
I checked the temperatures again.  The Hakko seems to be about 70C cooler by the meter than I'd expect.  The 300C setting runs about 230C.  The 400C setting runs about 330C.
 
This seems low.  I'm not sure if they measure a different point than I am - I'm measuring the very tip, where you'd solder from, with a very lightly tinned tip - or if they measure at the base of the tip.
 
I also don't know if I trust my meter's temperatures.  At the 300C setting, it meters to 230C, but will still melt solder.  The data sheet for the solder I'm using says that's 321C.  Those don't line up somewhere.
 
Turning the Hakko up from 300C to 350C helped, whatever temperature that is.  I may look into calibrating the iron, but I'm not really that concerned about the actual temperature as much as I am soldering properly.