New Hakko Digital Solder Iron and FET

Ron,

You should not need any flux when doing electronics.

Dave

Generally the solder brands have rosen flux inside the solder...one brand is called Multicore. And Kester...

https://www.amazon.com/Kester-...JMTPC2BG7EFGRN87STFE

But, sometimes the copper strands are oxidized and coating them first with a little gel flux or my choice called Sal-Met of which I bought a pint about 25 years ago and still have a third of the bottle left. When you put it on the joint, it cleans and also helps prevent oxidation of the metals when soldering.

I use 650F for most of my PCB work.  If I'm working with a surface mounted power package like a TO-263-3 package with a large tab soldered to the PCB, sometimes I'll kick it up to 700F.  Not familiar with Sal-Met, but if it's at all acid based, I'd keep it miles away from any electronic work! 

If you're talking about the LR024N SMT package, probably 700F.

I think it is very mildly acidic. Sal Ammoniac and lard probably. I don't use it on pcb or kits, etc. Mostly when an old copper wire or one that has oxidized badly won't tin. In 25 years I have never had a long term issue with it. It's soluble in alcohol.

Not trying to hijack the thread, but I do have some additional questions.. My soldering 'background' is mostly automotive components which have bigger wire-18ga and larger.. Of course layout wiring also.. I recently purchased a Solomon SL-30 Digital Soldering Station, which I have yet to use, to solder ~ 28ga wire et al.... I was using Sosmetal 812620 High Strength/ Low Temp solder.. The composition of the solder is not stated.. It has a Rosin Core, and I know it has lead in it based on the "Warning" on the back..

Questions:

1. Should I toss this  Sosmetal solder or continue to use it..

2. Purchase the Kester listed above?? That's more solder than I'd use in a lifetime..

3. Any other solder recommendations..

The Sosmetal 812620 is standard 60/40 Rosin Core solder, should work fine.  I use the 63/37 Rosin Core solder because it's an eutectic alloy that has a single temperature that it solidifies at, 60/40 has a range where it's between the liquid and solid state. This can create a cold solder joint if things are moved.  The lead-free solder types are much more problematic for me, and even though I have some, I avoid using it.

Woodson posted:

 

2. Purchase the Kester listed above?? That's more solder than I'd use in a lifetime..

 

It's only a pound...get it before they outlaw lead in solder. Just don't hold it with your teeth when you need an extra hand.

I've gone through a number of pounds of solder in the last couple of years, I try to keep several pounds in stock.  I buy the 63/37 mix.

First off, eye protection recommended.  Everyone has their favorite technique but here's what I suggest:

First remove the two legs from their pads one at a time.  If you have a sharp miniature diagonal cutter you can cut each leg off the FET right near the black body...then remove the legs from the pads by heating the pad for a few seconds and lifting off the amputated leg.

If your cutter is not sharp you risk pulling the leg and its pad off the board when you try cutting the leg - not good.   In which case I'd put a dab of your gel in the red areas.  Then heat one leg in the red area and after a second or two bend the leg up off the board using a fine needle-nose or equivalent.  Then same for 2nd leg. 

Then go to the FET metal tab area in red.  Try to get as much of the iron's heat to contact the red box by angling the tip. This one will probably take, say, 5 seconds of heating before the solder melts and you can lift the part off the board.  Use some finesse when lifting lest the molten solder goes flying into your face. 

cjack posted:

Woodson posted:

 

2. Purchase the Kester listed above?? That's more solder than I'd use in a lifetime..

 

It's only a pound...get it before they outlaw lead in solder. Just don't hold it with your teeth when you need an extra hand.

Talked me into it.. Just spending a bit of my daughters' inheritance.. lol

Quick question for the electronic gurus. Which thickness would recommend for the  63/37 Rosin Core: 031, .015, .020. and .080 .

I'd go with the .030 or .020...maybe .020 these days.

I use .020 for PCB work and .031 for general wiring, etc.

I agree 100% with Stan's removal method, that's exactly how I take chips off.  I clip any leads I can and then sweep the little legs off with the iron.  Far less damage to the PCB than excessive heat.  As for the large tab, I secure the PCB, and then I grab the chip with pliers and heat the tab as Stan suggests.  When it's loose, just lift it off.

To put the new one on, I first clean off excess solder from the PCB.  Then I position the chip and solder one of the small leads to align it, and make sure it's flat as possible on the PCB.  Solder the other one, and finally flow the solder under the tab, it should wick under very readily once it's hot enough.

stan2004 posted:

First off, eye protection recommended.  Everyone has their favorite technique but here's what I suggest:

First remove the two legs from their pads one at a time.  If you have a sharp miniature diagonal cutter you can cut each leg off the FET right near the black body...then remove the legs from the pads by heating the pad for a few seconds and lifting off the amputated leg.

If your cutter is not sharp you risk pulling the leg and its pad off the board when you try cutting the leg - not good.   In which case I'd put a dab of your gel in the red areas.  Then heat one leg in the red area and after a second or two bend the leg up off the board using a fine needle-nose or equivalent.  Then same for 2nd leg. 

Then go to the FET metal tab area in red.  Try to get as much of the iron's heat to contact the red box by angling the tip. This one will probably take, say, 5 seconds of heating before the solder melts and you can lift the part off the board.  Use some finesse when lifting lest the molten solder goes flying into your face. 

 

Stan,  I do not agree with cutting at body.  I have seen it lift the leg pad when the leg moves away from the body laterally.  I use a cutter with diagonal up and cut low at the pad.  This lifts the cut leg while putting downward pressure on pad.  I do this for all chips I cut.

As far as the tab removal, that will take some heat.  So I switch to a wider tip which get more heat in the area in a faster time frame.  Apply heat with tweezers on the body to lift once the solder melts.  If a difficult one, I might flow some solder in at the tip to tab joint to assist melting the body solder.  Up it comes.  G

Look around the thing you are working on, including the case. If it says ROHS or if it has Pb with the circle slash thingy, it is for sure lead-free. Lead free is harder to work with and will need a higher temperature.

If your Hakko is like my Hakko, it has a temperature sensor near the tip, and when the temperature drops, it kicks up the power, reducing the need for a bigger soldering iron, and in general making your life easier.

I like the clip the small leads idea, as long as you are SURE that part is bad. Don't pull on the clipped legs too soon or you will lift the copper trace and come up with a new swear word.

If you have ANYTHING else in your house you could give two hoots about, I would try a few unsolders on that first.

I learned a technique at a previous job, they had this tool that is like a heat gun, shoots a concentrated stream of hot air, you point it at the chip and apply a gentle sideways force, when its ready, it moved, this is for chips with small pins though.

That tab on the new FET is going to be a bear to do right, we have a problem at work with voiding under the component, the voiding reduces thermal conductivity and the component over heats.

I'd like to thank everyone who contributed to this post.  The tips and suggestions gave me the confidence to proceed with the replacement of the FETs on my slave board.

I set the temp of the FX 888D to 700 degrees, cut the 2 legs on each FET, heated the heatsink and used tweezers to remove when loose, then heated the remaining pieces of the legs and removed them.

I then used no clean gel soldering flux to stick the new FET's in posiition while I held it down with tweezers and soldered the legs. I finished up by using 37/63 solder on the heatsink allowing it to flow around and wick in.

When placed on the track & connected to the A & B units it performed perfectly.

Thanks again,

I really appreciate the help,

Ron

upguy

Gosh, I love success stories.

Newbie to soldering and also have the Hakko FX  888D.  I was soldering to Ross switches for non-derail with 63/37 rosin core solder.  What's the best temperature setting to use for this purpose and for general soldering?  The default setting out of the box was 750, but that seemed too hot.  Should it be lower ?

Mike

I use 650F for general soldering, when I'm soldering something fairly large, I may bump it up to 700F or even 750F.  For PCB work, I drop it to 550F, and for certain delicate parts, I go down to 500F.