Soldering - wetting

I am learning to solder by working through some small projects in preparation for building the ST-120 (which arrived today). About a quarter of my solders have poor wetting - do not completely cover the copper. In trying to diagnose my poor results I have pre-cleaned the copper with 99.9% iso alcohol, am tinning and sponging the tip before soldering, am soldering with 60-40 solder at 675 degrees. I put the iron to both the wire and copper and apply the solder to the other side. If any of you have advice on what I might try to have more consistent wetting I would appreciate the input. Thanks.

Are you trying to use lead free solder or something? That stuff is harder to work with, outside of that practice makes perfect.

No I am using 60-40.

Ok, the only other thing I might recommend is getting some extra flux to paste on prior to soldering.

OK, I have extra flux I can use, thank you for the response.

I noticed that my hakko tips are plated with lead-free solder. I am going to put a new tip on and make sure I do the inital re-tinning properly with my leaded solder. I likely did not do a good job with the initial re-tinning for the tip I am using.

I set my Hakko to 725-750 degrees. If you do this, try to make a good connection in a few seconds. Diodes and the IC's are sensitive so use a heat sink on the leads or be quick. I go hotter or longer if it's a big piece of metal, ie: rear speaker terminals, star ground, etc. The driver board tube sockets will take a little more time but you want to use a good amount of solder here as tubes are being installed and removed and the solder anchors the sockets. Fresh solder on the tip just before making a connection puts fresh flux into the joint.

Pardon me if I'm rambling...

Look for more soldering videos as well.

Maybe a dumb question- you are using rosin core solder, yes?  In my decades of experience with good solder joints (mostly electronic) and bad solder joints (mostly plumbing), I've found that tip preparation is very important- I tin the tip of the iron with my 60/40 rosin core, wipe it dry, and do it again.  Make sure the solder flows onto the tip quickly and completely.  I also leave a bit of solder on the tip to make good thermal contact with the conductors to be soldered.  You probably know all this.

I am using rosin core solder, yes. And not a dumb question. I have not soldered before. I've watched numerous videos. I have been tinning the tip, but perhaps not doing it well. That seems like a likely culprit, not getting good thermal exchange to the pad.

Used iron plated copper tips if available.  Unplated bare copper will drive u crazy with constant cleaning, scraping, filing, whatever.  And it tends to disintegrate fast.

Even plated copper requires due diligence in cleaning and prepping, but the improvement is miraculous!

Here's how I do it, take it with a grain of salt as you should with anything you read on the web. This works for me:

I set the Hakko FX888D at 650 and use 63-37 or 60-40 depending on what I'm doing (new work, rework..etc.). My method is clean the tip with a Hakko brass pad solder tip cleaner (or equivalent) no wet sponge that thermal shocks the tip, and then dip the tip into a quality Tip Tinner like a Thermaltronics. Now ready to solder the joints. Apply a tiny amount of your choice of solder on the tip and put iron to parts. When done with that round, clean with brass pad and re-tin, set it down. When ready to do another round, clean tip with pad, re-tin and solder. Examine tip often to ensure the tinning is even on the tip, no un-tinned spots. Never take a file or sand paper to a tip. Make sure the tip is newish clean and shiny before using it. Before I start I like to spray contact cleaner on my boards/contacts. For the legs of parts, I use a little 0000 steel wool (or 1000 grit paper) around where the solder will be on the leg of the part. Very lightly with the wool, just to bring out a little shine on the tinning that's already on the legs. Then clean the leg with a little contact cleaner (use Kimtech wipes) Keep an eye on the particles from the steel wool that they don't find their way into the work ( I find the 1000-2000 grit to be better). The key is clean everything, board, parts, tip and it will come out perfect.

Thanks cci,

Based on what you wrote I changed the way I tin my tip.  I just tried dipping the tip into my rosin paste flux a couple of times before tinning with solder (and retinning after a couple of solders).  I just did 6 in a row that all look good  - nice, shiny domes (sadly, a record for me).  Anyway, I am cautiously optimistic - just in the nick of time because I am tackling the VT-120 board tomorrow.  Thank you everyone who offered advice.

And I stopped using my sponge - and only used the copper cleaning wire.