Through hole soldering problems

[Stuartambient]

This is definitely the smallest holes I've had before. Very little metal around the hole as well.  The holes with copper is 1mm diameter, chisel tip is 1.5mm. 

The problem I'm experiencing is getting tip onto the hole to transfer enough heat and still have room to get the solder in.   I'm finding that the solder is balling up on the tip because there isn't really any room to slide the solder in from the other side.  I have some conical tips but it's useless.  Wondering if maybe there are any special tricks or tips in dealing with this situation. 

It's possible the solder should be a smaller diameter.  This one is .032" so around .8 mm.  I have some .6 on the way. 

[mariush]

Flux always helps. Apply some liquid flux.
Make sure you touch the pad and the lead with the iron tip before bringing the solder, so that the liquid flux will have time to clean the surfaces (leads and pad).  Will also give the flux inside the solder wire time to activate and do its job.

[BMack]

Flux and use the corner of the chisel tip, thinner solder will also help. I do like this tip from Hakko https://www.amazon.com/gp/product/B00762AHYY/, it tapers rather dramatically so the thin tip actually gets hot enough to work unlike most conical tips. The most important thing for this particular joint is adding liquid flux.

[Stuartambient]

I generally prefer, when I use it, flux paste, the thick kind of depending on the job, either use a brush or a toothpick for minute amounts.  I was considering thinning some down with ISO but after a little searching there were some reports that the iso will get into the joints creating cracks.  Not sure if that is true or not but it was enough for me to nix the idea. 

I will  get some liquid though but I will say there is quite a bit of flux in the solder itself and already have it running around and into the joint.  I just don't want the flux running onto the other side of the board.

[tatus1969]

preheat the board area with hot air to 100degC.

[kg4arn]

Not sure if this will help:
Flux the pad as others have said.
Clean tip.
Apply a ball of solder to the tip.
Bring tip to the pad and molten solder will heat the pad even if the tip doesn't make contact and voila it's done. Repeat if it needs more solder.

[Kleinstein]

There is no need to have a really small tip. So even a rather large (e.g. 6 mm / 1/4") wide cisel tip ok for small parts (e.g. SO14 SMT parts). The problem are usually not small parts (unless the wire is less than some 10 µm / 0.5 mil) it is large power parts (e.g. > 2 mm diameter copper) that get difficult.  To small a tip can cause problems as it cools down to fast and thus causes slow soldering, possibly overheating sensitive parts.

[CraigHB]

Yes you have to watch out for fine tips, because they're so thin they have to be short.  Otherwise they lose to much heat at the tip.  For fine PCB work I use a .015" (0.4 mm) wire solder.  Liquid flux and fine wire solder should take care of the problem.  A freshly cleaned and tinned tip is important as well.  I commonly solder wires or component pins in through holes with only a .2mm annular so it is possible.  It is a little more difficult, but not too much trouble really.

[Stuartambient]

I commonly solder wires or component pins in through holes with only a .2mm annular so it is possible.  It is a little more difficult, but not too much trouble really.

I'm not understanding this part, is the tip annular?

[imidis]

Flux it good. Having a little bit of solder on the tip will help heat transfer and flux will also help it heat up better.

[John Coloccia]

Instead of laying the iron flat, twist it so the side sits on the pad, and the flat face sits on the lead. Sometimes I do that anyway to transfer more energy into the lead because the lead often has far more thermal mass to heat up than the pad.

[Stuartambient]

So I tried all these great tips, well most since I don't have the Hakko tip (above) or the thinner solder.  Still having about the same hit and miss.  Here's the thing though, in the past I've generally had copper pads or holes to solder through, but these are silver rings.  I'm wondering if that is part of the difficulty.  Maybe they are copper but the color is silver.  Haven't seen these before in my limited experience.  Any take on it?

[John Coloccia]

They just look like plated through holes, but it's hard to tell because the picture is very blurry. The big ones on top look like they have thermal reliefs, so they're probably going off to some sort of large copper pour and will generally require more/faster heat transfer to solder effectively.  For that, be absolutely sure that you establish a good solder bridge (do this anyway), and dwell a little bit longer before applying the solder. It may not hurt to turn up the heat a bit, but as always be careful.

Do you have a proper temperature controlled solder station? If not, a lot of your problems might disappear just by getting one.

If there's room, you may also want to angle the soldering iron to get one side on part of the ring, and the front part actually a little INSIDE the hole and touching another part of the ring. It's very difficult to describe how to do it, but you're not really going inside the hole. More just on the very edge. You're just trying to get the maximum contact area for best heat transfer.

[THATguy]

You can buy flux pens - they are great!
Air soldering iron is the ideal if you can get one.
Otherwise place your tip on those holes to pre-heat them. Then flux (if you have).
Also you could try filing a piece of solder very thin to poke through with the wire, now you solder and it should break off, but one end hopefully will solder on, and you do the other side the same, as best you can. Do the side that has less room first, then you'll know if the solder is good before finishing the good side.
One more trick you might try. When your iron is cool wind a clean strong bit of copper or stainless steel wire (paper clip) around the tip of the iron. You may want to double back over, winding in opposite direction with one wire end for extra grip. And one end of this is straight out from your iron tip up to 20mm. Then you can really get into those tight places.

Soldering if the most difficult temperamental tedious thing I've ever done in my entire life (with a standard iron).
But cleaning the end of your iron with steel wool, and I always have a heavily soaked kitchen sponge on hand, lightly pressing the iron tip on to help keep it clean as I work (this will cool the end a bit, so you might have to wait a moment for full heat to return).
You may notice a black scale come off and the copper tip revealed, this is good.

[tautech]

So I tried all these great tips, well most since I don't have the Hakko tip (above) or the thinner solder.  Still having about the same hit and miss.  Here's the thing though, in the past I've generally had copper pads or holes to solder through, but these are silver rings.  I'm wondering if that is part of the difficulty.  Maybe they are copper but the color is silver.  Haven't seen these before in my limited experience.  Any take on it?

I've not seen you mention the solder you're using or whether it's that Lead free muck or not. 
For most TH work a 3mm chisel tip has sufficient thermal mass but some prefer a Hoof style that I imagine is better still.
Leaded fluxed solder and a tip with enough thermal mass along with sufficient dwell time on the joint and you should have success.

[Stuartambient]

I've not seen you mention the solder you're using or whether it's that Lead free muck or not. 
For most TH work a 3mm chisel tip has sufficient thermal mass but some prefer a Hoof style that I imagine is better still.
Leaded fluxed solder and a tip with enough thermal mass along with sufficient dwell time on the joint and you should have success.

Lead-free? Never heard of it.   

I'm trying to avoid using something that is 3x the size of the hole which the 3mm would be.  I have used large tips on small pads but you know it's not recommended generally for good soldering practices 

They just look like plated through holes, but it's hard to tell because the picture is very blurry. The big ones on top look like they have thermal reliefs, so they're probably going off to some sort of large copper pour and will generally require more/faster heat transfer to solder effectively.  For that, be absolutely sure that you establish a good solder bridge (do this anyway), and dwell a little bit longer before applying the solder. It may not hurt to turn up the heat a bit, but as always be careful.

Do you have a proper temperature controlled solder station? If not, a lot of your problems might disappear just by getting one.

I have a cheap knockoff (so not proper ) temp controller station.  It's okay though and while I don't have the ability to measure the temp I feel it's pretty spot on for the setting.  Generally set to between 650-700F

I've twisted the tip in various directions but using the same technique still produce varied results.

What I see on the component side, for most of the connections, solder came through the hole and formed a solid joint.  Not on all of them though but most.  What I see in those cases the flux is filling the top of the hole (on the soldering side) and the solder won't take, making it difficult to get a nice filet cap on the soldering side.  Hopefully this makes sense. 

[tautech]

I've not seen you mention the solder you're using or whether it's that Lead free muck or not. 
For most TH work a 3mm chisel tip has sufficient thermal mass but some prefer a Hoof style that I imagine is better still.
Leaded fluxed solder and a tip with enough thermal mass along with sufficient dwell time on the joint and you should have success.

Lead-free? Never heard of it.   

I'm trying to avoid using something that is 3x the size of the hole which the 3mm would be.  I have used large tips on small pads but you know it's not recommended generally for good soldering practices 

Sorry but where'd you get this idea from...............it's BS. 
Use the tip and temp that works and adjust you dwell time to get a good wicking and flow of the solder.

I have a cheap knockoff (so not proper ) temp controller station.  It's okay though and while I don't have the ability to measure the temp I feel it's pretty spot on for the setting.  Generally set to between 650-700F

I've twisted the tip in various directions but using the same technique still produce varied results.

What I see on the component side, for most of the connections, solder came through the hole and formed a solid joint.  Not on all of them though but most.  What I see in those cases the flux is filling the top of the hole (on the soldering side) and the solder won't take, making it difficult to get a nice filet cap on the soldering side.  Hopefully this makes sense.

It does and it doesn't. 
It seems to me that you're trying to solder with insufficient heat. 
Crank your iron up at least 50⁰ or more, watch the solder flow and vary the time on the joint to suit. (dwell time)

[John Coloccia]

What are you using for solder?

[Stuartambient]

What are you using for solder?

60/40 Rosin core

[Stuartambient]

Sorry but where'd you get this idea from...............it's BS. 
Use the tip and temp that works and adjust you dwell time to get a good wicking and flow of the solder.

I'm not completely disagreeing with you but I've come across the suggestion to match tip size to work area numerous times, the latest in a book "Intro to High Reliability Soldering and Circuit Board Repair" by Norman Ahlhelm. 

I have a cheap knockoff (so not proper ) temp controller station.  It's okay though and while I don't have the ability to measure the temp I feel it's pretty spot on for the setting.  Generally set to between 650-700F

It seems to me that you're trying to solder with insufficient heat. 
Crank your iron up at least 50⁰ or more, watch the solder flow and vary the time on the joint to suit. (dwell time)

Maybe but it seems to melt the solder well just not always going in the right direction. 

[tautech]

Sorry but where'd you get this idea from...............it's BS. 
Use the tip and temp that works and adjust you dwell time to get a good wicking and flow of the solder.

I'm not completely disagreeing with you but I've come across the suggestion to match tip size to work area numerous times, the latest in a book "Intro to High Reliability Soldering and Circuit Board Repair" by Norman Ahlhelm. 

I have a cheap knockoff (so not proper ) temp controller station.  It's okay though and while I don't have the ability to measure the temp I feel it's pretty spot on for the setting.  Generally set to between 650-700F

It seems to me that you're trying to solder with insufficient heat. 
Crank your iron up at least 50⁰ or more, watch the solder flow and vary the time on the joint to suit. (dwell time)

Maybe but it seems to melt the solder well just not always going in the right direction.

I get all that you're saying, a comment though: don't trust your stations temp setting as correct.
Mine's in C and I generally have it set at ~350 (sometimes more) and for TH I always use 3mm tip unless room is a constraint.
Theory gained from books should be considered as a guideline and no substitute for real experience along with the fact they have temp calibrated stations, something many of us don't.
Having been soldering for nearly 5 decades I analyse your problem as too smaller thermal mass tip and too lower temp. Crank the temp up a bit, once to combat the lack of tip thermal mass and again to get to where you need to be.
Grab an old PCB and give these things a try, don't worry that there's solder on them already just add more, suck it off and try some more. It's not so much a science as practice.   

[raspberrypi]

When i was a kid I thought my soldering skill were shit but I found a few things:

The soldering iron makes a huge difference, the haykko set to 650'F is a huge help. I got mine for 100 bucks on amazon and its already paid for vs buying the 40.00 rip offs they sell at home depot.

Preheat the area, tin the tip and let the copper warm up for 2 seconds then apply the solder to the copper or the wire not the tip.

Sometimes a small ball on the tip helps to conduct heat to the part.

Practice, soldering is so easy compared to welding and other metal gluing together applications..

[ieast]

When I'm soldering small components, I find a cheapo Amazon $8 head magnifier with light makes the job a lot easier.

[eKretz]

Tip size is not what's causing problems here - it's inconsequential in this instance. The main thing about matching tip size to work is not to have too small of a tip. Too large won't ever cause any problems unless it's a very tight area and won't physically fit or will disturb neighboring joints.

I'd say the advice already put forward is very good. I would have said to be sure to use extra flux, make sure your tip is clean and tinned, and add a small amount of solder to the tip before making the joint to help with speedy heat transfer. If the tip won't take solder and it's balling up, I'd wonder if there's a problem with cleanliness. Personally, I find soldering to be quite simple and very easy - not finicky at all.

[Stuartambient]

I'd say the advice already put forward is very good. I would have said to be sure to use extra flux, make sure your tip is clean and tinned, and add a small amount of solder to the tip before making the joint to help with speedy heat transfer. If the tip won't take solder and it's balling up, I'd wonder if there's a problem with cleanliness. Personally, I find soldering to be quite simple and very easy - not finicky at all.

No, I was looking at the Hakko page on how to choose a solder tip yesterday. It's shows 3 different tip sizes in relation to the same work area. Graphs show time a and temp comparisons between the three.   Their recommendation in all the instances was to choose an "appropriate" tip (their word) which is the one that matches the size of the area to be soldered.  They say a bigger tip will cause damage to the pcb.

Anyway, no I take care of the tips, tinning during session, use a brass sponge and the tip takes the solder well. A better station is in the works though, probably the Hakko 988.  This station though is alright, it can get the job done though it takes a bit longer to heat up, I believe the temperature is consistent.  It's just strange but sure it's me and my technique. I mean the solder is flowing on a good number of the joints because it went into the well and formed on the component side.  So it must be my technique more then anything.