Soldering Advice


 
B

Bob C

TVWBB Member
I'm somewhat new to soldering and have tried a few times in the past and am terrible at it.

When putting together the HeaterMeter board, I had a lot lot of trouble getting the solder to stick. I got better at it and the LCD board went together a lot better. I think it has to do with my liberal use of the flux.

The Heatermeter board isn't working so I am going to go back over all my connections.

When I was soldering the HeaterMeter board, I was trying to heat up the component lead then apply the solder to the lead and not the iron. At times the hot iron may have been on the lead for 20-30 seconds. Because of this, could I have damaged the components or the board from the heat? Should I start over with a new board and components?

Also, I was redoing one of the components last night. I got the solder removed but then no matter how much flux I used I couldn't get the solder to flow to the lead and the board. Is there something else I need to do if I am redoing a connections? Should I clean the board and lead with something after the solder is removed?
 
I never use external flux when I solder, even when I do SMD stuff. It might be your choice of solder? I use Radio Shack 60/40 0.032" rosin core solder, where the rosin is the flux. Are you maybe using leaded solder with no rosin? Maybe your soldering iron is not hot enough? What are you using for solder and an iron? It should only take like 2-4 seconds to heat the lead enough for solder to flow.

Also what helps is the right steps 1) clean your tip on your sponge or metal fluffball 2) put a small amount of solder on the iron tip to allow better heat conduction 3) tip to lead 4) solder to lead 5) let solder melt and collect 6) remove solder 7) remove iron. Sounds like you've got steps 3 to 7 right though.
 
It sounds like your soldering iron isn't getting hot enough. I typically solder at around 360-370C. If you're not using rosin core solder, that could also be your problem. You really shouldn't need to apply flux to anything unless you're fixing up a connection after the fact.
 
When soldering you always want to "tin the tip" of the soldering iron first. This means apply solder to the tip of the soldering iron so it is coated. To clean the soldering iron you can rub it on a wet sponge. When soldering you want to heat the trace on the board and the component leg at the same time, not one or the other. It should be done as quickly as possible... Flow a little solder to the tip of the iron, press the iron to the board touching the trace and the component leg, flow more solder to the iron and it should flow down to cover the component leg and the trace.
On the HM board in general, I had one sitting around for a long while and found it didn't take solder well when I finally assembled it. Maybe it has something to do with the board material and/or manufacturing process used at OSHPark? If you order custom boards they are made fresh, if you order something they stock like the HM board they may have sat a while, not sure how many they run at a time over there and how fast they sell. Putting a little bit of flux on the board before you assemble makes things go easier...
 
Bryan Mayland said:
I never use external flux when I solder, even when I do SMD stuff. It might be your choice of solder? I use Radio Shack 60/40 0.032" rosin core solder, where the rosin is the flux. Are you maybe using leaded solder with no rosin? Maybe your soldering iron is not hot enough? What are you using for solder and an iron? It should only take like 2-4 seconds to heat the lead enough for solder to flow.

Also what helps is the right steps 1) clean your tip on your sponge or metal fluffball 2) put a small amount of solder on the iron tip to allow better heat conduction 3) tip to lead 4) solder to lead 5) let solder melt and collect 6) remove solder 7) remove iron. Sounds like you've got steps 3 to 7 right though.
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I was using a SOAIY 60w soldering iron kit I bought from Amazon. At first I was using the solder that came with the kit. The label says Lead Free, .8 DIA, SN-0.7 CU, 2% flux. After that wasn't working well I switched to another tube I had laying around that I think the package said rosin core but not positive. I'll go and get the Radio Shack 60/40 0.032" rosin core solder tonight.

The iron was usually set to 350 degrees Celsius.

I was doing steps 1 -7 but it didn't seem like the solder would melt unless I put the solder to the tip of the iron instead of the lead and then the solder usually stayed on the iron when I removed it from the lead.

If I don't need the flux, should I be cleaning the board with anything like alcohol before I solder the joints?
 
I don't think your iron is hot enough. I wouldn't trust the temps on the dial gauge to be accurate. Turn it hotter. The solder should instantly melt when touched to the tip. Also make sure your tip is tight in the iron.
 
Bob, years ago, I worked for USRobotics/3Com/MSL, in factory IT. New PCBs came in, were unwrapped, and went straight down the line, no cleaning other than maybe a fixed dust brush at the unloading station. As long as the solder pads are bright silver in color, there's no real need to do any solvent cleaning. I put my 4.2.4 HM together without even wiping it off.

The other recommendations are pretty much dead on. Sounds like your iron isn't hot enough, and that needs to be CLEAN. Use a very fine grit sandpaper GENTLY to remove any oxides on the tip, wipe it frequently on a damp sponge when in use, keep the tip tight, and keep it tinned.
 
I'd also suggest getting a "brass sponge" for keeping your tip clean. They're super cheap and don't require any water. Just stab the tip into the brass sponge a couple of times and it's nice and clean.
 
OSHPark boards are gold finished and should not usually require cleaning. More bare boards (plain copper) oxidize if you look away for a minute and would require cleaner. The ones I make on my CNC (bare copper) are picky to solder. Most quality commercial boards will be coated.
 
A bottle of rosin for the beginner, Is nice to have to make good joints, without even trying too. It's also handy to have when you need to use soldering wick to desolder. I always add rosin to whatever I'm desoldering and the solder is removed much more easier then without, even though solder wick has some rosin already on it, it's not enough.

Depending on what brand is used, you either leave it on the board or you need to remove it. The stuff from Fry's takes all of it off in a few seconds of spraying and leaves nice clean board that has a layer of protection.
 
Bob C said:
I was using a SOAIY 60w soldering iron kit I bought from Amazon. At first I was using the solder that came with the kit. The label says Lead Free, .8 DIA, SN-0.7 CU, 2% flux. After that wasn't working well I switched to another tube I had laying around that I think the package said rosin core but not positive. I'll go and get the Radio Shack 60/40 0.032" rosin core solder tonight.

The iron was usually set to 350 degrees Celsius.

I was doing steps 1 -7 but it didn't seem like the solder would melt unless I put the solder to the tip of the iron instead of the lead and then the solder usually stayed on the iron when I removed it from the lead.

If I don't need the flux, should I be cleaning the board with anything like alcohol before I solder the joints?
Click to expand...

The problem is the lead free solder. It is much harder to work with, even for the experienced. It requires a higher temperature to flow. Find some of the good leaded stuff and you will be much better off.
 
I got some Radio Shack 60/40 0.032 solder the other day and on a couple of test joints it seemed to work much better. Since my heatermeter isn't communicating, my plans are to de-solder the components with the problem solder joints and resolder them. Hopefully the soldering will go better this time around
 
The flux in the rosin core solder should be plenty of flux. You shouldn't have to put the soldering iron on the pad, just the lead of the component (It's not all that bad to get it started directly on the iron as long as you can see its flowing well on the lead and the pad). You can easily damage a board leaving the tip on it that long. I usually put some solder on to the tip of my iron to clean it and then run it through a brass cleaner or wipe it with a wet sponge. Liquid flux can be handy sometimes. I used to hand solder 100 pin surface mount ic's with that stuff. Don't mess with paste flux. That stuff is nasty. I only soldered a few times with the non-lead solder but it didn't seem that much harder. It was just had to be heated up more, didn't solidify as quickly and didn't look as good as lead solder. I typically used 63/37 which is nice if you can get it. I haven't soldered on a heatermeter board. It doesn't look to crazy with large ground planes or anything. Those can soak up a lot of your heat.

Do not desolder the components and re solder. Just reflow them. You can do that using flux, or just add a little solder an reheat the joint and make sure it looks smooth. When you add solder you are really just using the flux in the core. Wipe off any excess solder from the iron tip on a wet sponge or if you are really in a pinch a damp paper towel folded up can work.
 
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Steve_M said:
Can you take some high res photos of your board and post them? It might reveal something.
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I got some 60/40, a brass sponge and a flux pen. Using the information in this thread, the soldering has gotten better but I still have a long way to go. I fixed up some of the joints but the heatermeter still isn't working.


Here is a before Pic

IMG_5709_zpsuzjvxqyi.jpg



Here is an after I cleaned it up

IMG_5722_zpsqwdkpuqc.jpg
 
You are missing a transistor. I csn see an open spot for a bs170 or a mcp1700. I can also see some pads not getting a good connection to the components. I would start by adding some solder to each pad. Make sure you heat the pad and the component leg at the same time, then add the solder, remove the solder and then remove the iron.

Remove the long leads on some of your components. You have some that are bent over. It's a good way to get a short.
 
I would apply some flux to most of those joint and reflow them. Keep the iron on each joint for 2-3 seconds. After you are done, give it acetone and a toothbrush scrub.
 
Put the soldering iron tip on both the pad of the board and the component, with an emphasis on the pad. A lot of heat and a little solder is the way to go.
Your after picture looks much better than the before.
 
Bryan Mayland said:
More importantly, that's the 3.3V regulator! Good eye, John. So there's no power going to the microcontroller which is why it won't communicate.

That is an amazing cleanup job you did, my hat's off to you.
Click to expand...

In the event that his 3.3V regulator has gone missing, is there any harm in using the 3.3V from the RasPi to provide 3.3V, like the old HM 4.0 boards did?
 
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