Hakko T15 tips not putting out the heat - just crank it? Yes? No?

[Fried Chicken]

I'm running my FM-206 that I'm very proud of, but on several instances, especially with the smaller tips, I'm wanting for more power.

Do these tip temp sensors get unreliable with use/age?  Are the smaller tips inherently less reactive to changes in temperature?  On one hand I guess I could get a tip temperature probe and do all of that...

Or I can just crank it?  Is there a reason not to do so?  I understand "oh no you'll burn/damage something", but I feel the benefits of working quickly outweigh the drawbacks of higher temps.

My current setup is programmed for ideal temperatures for 60/40, 63/37, and lead-free solder.

Perhaps too the problem is with the lead-free tip tinner I'm using:
https://hakkousa.com/amfile/file/download/file/1200/product/9526/

I've heard the JBC tip tinner is very good

[RoGeorge]

- The thumb rule is to have a large, thick enough soldering tip.  For example, if you use the chisel type, the width of the tip has to be about the size of the pad, or even wider than the pad footprint you want to solder.
- Second rule, the thermal resistance of the tip, use the shortest tip.  The long and thin conic shape have less thermal power.
- Third, and as a last resort, you can crank up the temperature, but take care to not melt/carbonize the components (for example the plastic in connectors).  Another risk with high temperature is to exfoliate the PCB pad and/or traces.  High temp will oxidise and "eat" the soldering tip faster than normal temperature (soldering flux become more corrosive at higher temperature).

Big brands have a support section with advice/motivation for how to choose the correct soldering tip, how to use it, what temperature to use, and so on.  For example JBC has:
https://www.jbctools.com/prolonging-tip-life.html
https://www.jbctools.com/video-guides.html
Other brands have similar recommendation.  It worth looking at 2-3 more brands, to identify what are the most common good practices.

[ygi]

It's all about the geometry of the tip. For starter, T15 don't have that much thermal mass as they are mostly hollow. When a tip's thin, it lacks contact surface to transfer energy to the PCB and if it's long, it will also be much less sensitive to temperature changes (ie: PID loop can't sens and compensate heat loss). Just look at a fine long tip with a thermal imager, you'll see the wet tip isn't where the heat concentrates.
So, should you crank up the heat? Well, first I'd check that the long cartridge is actually calibrated at the part that's in contact with the PCB. That can be an issue for stations that don't offer per tip profile but you can't do much about it... Anyway, once you ensured that your tip gets you the temperature you set but it's still not quite enough to melt solder, you can crank it up within reason. If you have to go over 400°C, you're simply using the wrong tool and you'll just damage it or whatever you're working on. You need a preheater or/and a soldering station that's actually designed for sub-millimeter microsoldering (like popular JBC's C115 or C210 lineups). T15 is more for general purpose soldering like THT and mid size SMD.

Also, you shouldn't use tip tinner unless you've burned your tip and it doesn't wet anymore. It contains cleaning acid that's too aggressive for regular use.

[Fried Chicken]

I'll just use a larger tip for my application

[thm_w]

Assuming you are using genuine tips, the best performance you'll get is with something short and fat.
eg T15-D2, T15-B

But its still going to be inferior to a modern microsoldering specific tip like C115/C210 or anything RF based.

It's all about the geometry of the tip. For starter, T15 don't have that much thermal mass as they are mostly hollow.

Geometry is part of it yes. But thermal mass here is largely irrelevant. What you want is good coupling between the tip, the sensor, and the heater.
T12/T15 has the thermocouple and heater set quite far back from the tip itself: https://hackaday.com/2025/02/04/understanding-the-t12-style-soldering-iron-tip/

C210/C115 has incredibly low thermal mass but because the thermocouple is coupled so well and close to the tip, the performance often ends up better than a T12 tip. I guess OP can consider a T30 tip and handle, but new price is quite high.

[Fried Chicken]

I've found setting the temperature to 750°F worked wonders for both the tip and the desolder gun

[ygi]

If you hit that regularly or for an extended period of time, get some 3$ Chinese tips so you won't regret ruining your good ones.
Also beware of pads and vias coming loose when overheated. There's always a risk but it's significantly higher at that kind of t°.

[Shock]

Preheating is the way. If your work time is long you need to look at your whole process. It can be a mix of things being overlooked like how clean the tip and soldered surfaces are, flux and alloy type and quality, technique (it all adds up).

[Fried Chicken]

If you hit that regularly or for an extended period of time, get some 3$ Chinese tips so you won't regret ruining your good ones.
Also beware of pads and vias coming loose when overheated. There's always a risk but it's significantly higher at that kind of t°.

Sure, but you also risk pads and vias if you sit there cooking the PCB for a minute before trying to prod a component off.
Speed is the key;  Not to mention perhaps I'm correcting some hidden offset in the soldering iron (I don't have solder tip measure thing).  Also I'm already doing way better than with my old plug-in-wall resistive heating soldering iron.  I have 3 types of flux, solder, vacuum gun sucker thing, different alloys of solder, tips, the temp controlled interface.  I think I had one via go bad and I think it was at the lower temps.

Also the hakko tips are like $15 each or so, and they're not instantly going to get fried just b/c I go to 750°F a few minutes at a time while it's off the sleep station.

Just crank it.

[Shock]

Assuming you have flux cored alloy and a clean tip and board then one method of isolating it is with a reasonably low melt (soldering) alloy. Test tinning on a clean proto pcb at that low temp, about 1.25-1.50x of the melt temp. Try with a larger tip etc till you get a feel for the performance. Repeat with the alloy of choice, move up in joint size and pcb density. Then try reworking pcbs, you will start to feel where the sweet spot is.

You mentioned speed which is important, but you want to limit contact to about 3 seconds in most "typical" cases. If you are at a high temp and move to a very low thermal mass joint it could be too hot. Experienced solderers look at several indicators like flux boiling/evap speed and solder behavior and flow speed. As I said it's easy to overlook things just turning up temp. It's much safer (if you think it's a pcb/component density prob) to use preheating as it lowers the delta (difference in temp to make a correct joint) and median soldering temp (difference between temp for small and large joints).

Hope that helps.