How are therese conical pointy soldering iron tips supposed to be actually used?

[AndrejaKo]

So I've been soldering for a while now and don't really consider myself a beginner, but there's one aspect of soldering irons/stations which I do not really understand, and those are the sharp small conical tips.

For example, I'm currently mostly using a Pace ADS200 station, and I'm mostly using various types of chisel tips, however, for very small tip sizes, the only option seem to be conical tips. For example, here's a 0.2 mm tip that I have:
https://paceworldwide.com/1128-conical-020mm#overview

However, I with conical tips, I always have the issue, that when they start out, they're OK:

However, when I wet them with solder, the solder moves away from the tip a bit upwards, and then creates a ball, like here:

After that, the tip of the iron is mostly dry. Therefore, when I try to initially make contact with a pin, heat isn't being transferred quickly, and when I try to add external solder, it also tends to first make a contact with the ball of solder and not flow down the tip towards the pin I'm trying to solder. The wider part of the tip is probably hotter than the narrower end of the tip, which would then make the solder flow there.
So are there conical tips, which tend to come with irons by default, all just bad design which doesn't want to die, or am I missing something?

Also, I used the 0.2 mm tip in this example, but in my experience, larger tip tend to have same issues.

[joeqsmith]

Several years ago I switched from a water sponge to brass shavings.  I also use Pace's "Tip Brite".   I normally solder at 340 and limit it to about 370.  If I need more heat, I add it with a heat gun or torch. 

Even with that, I still run into the problem you describe.  However, it doesn't seem to cause me problems when soldering as I am still able to heat the joint.  Shown are some of my conical fine tips (maybe 20 years old now?).   

Here is an example of me using a fine conical to do some surface mount soldering under some poor conditions.

[shapirus]

I have the same issue with them.

However, when I wet them with solder, the solder moves away from the tip a bit upwards, and then creates a ball, like here:

I think that's actually their advantage in some cases such as soldering fine pin pitch ICs: since such a tip tends to remove excess solder from the soldering area, there is less chance of creating bridges.

It looks like they aren't supposed to be used with pre-wetting them with solder, but rather with applying solder to the joint when the tip is already placed at the joint and heating the pins/pads up.

[JohanH]

It looks like they aren't supposed to be used with pre-wetting them with solder, but rather with applying solder to the joint when the tip is already placed at the joint and heating the pins/pads up.

This. Add flux to the board, use a clean tip, heat the joint and feed a tiny amount of solder to the joint. I know there are multiple ways, but check out Mr SolderFix videos on youtube.

The really tiny tips should only be used in tight spaces. The larger the tip you can use, the better and easier.

The small, similar C245 clone tips that I have, don't behave in the way shown in the pictures. The solder sticks only to the outermost end of the tip, so they can't even carry blobs like that.

[mikerj]

The best way I've found of using them is to remove them and carefully place them in a dustbin.  They just don't have sufficient contact area to transfer the heat.

[janoc]

The best way I've found of using them is to remove them and carefully place them in a dustbin.  They just don't have sufficient contact area to transfer the heat.

Actually that's not quite true but you must not use them in the way most people do - i.e. by jabbing the sharp pointy end into the joint and waiting and waiting ... and waiting until the solder melts. If ever.

These need to be used by placing their side to the joint. Then you have plenty of contact area and heat transfer. The problem is that in many situations on a cramped board you simply don't have the space for that. That's where the bent tips (looking a bit like a hockey stick) come into play - majority of those are conical.

So one can use them but one needs to think about what one is doing. And in most cases there are better tips available for the task at hand.

[AndrejaKo]

Interesting idea!
One problem which I have here (but I need to try it out with some hockey-stick-like tips) is that when I use them lengthwise, it can often be a bit difficult to have a good contact with both the pin and the pad at the same time.
Here's a photo I tried to make, but I must admit that I'm not a good photographer...


What happens often is one of two scenarios:
I either make contact directly with the pin, as shown in this badly drawn image:

where then the tip tries to warm up the pin, and transfer heat onto pad. Usually, there's no room to add solder to the joint itself, so I have to add it to the tip, and hope that the ball will be big enough to make contact with pad and start transferring heat to it. During this period, the tip of the tip often stays dry, and the pin as well, so it doesn't seem as if it's a
Or it happens the opposite way:

Where I make contact with the pad, and solder makes contact with the pad too, but only the tip itself makes contact with the pin. Benefit here is that this immediately wets the pad, and if I add extra solder to the tip, it will flow down to the pad. Usually, the tip doesn't seem to make good thermal contact with the pin, but after a while, with controlled addition of solder, there will be enough solder to flow from the tip towards the pin, and then heat it up and make a joint.

[AndrejaKo]

By the way, while experimenting for writing the previous post, I figured out another way to use the tips, which seems to work, at least for QFP44 and similar packages.
Here are the steps:
First, I made sure that there's fresh flux on the PCB, and that the tackiness of the flux is holding the chip a little bit. A little bit of flat solder on the pads helps as well.
I cleaned the tip, and waited for a little bit, so it gets a little oxidized, but not too much. That's the key part.
While I have a little bit of oxides on the tip, I can add a little ball of solder near the tip of the tip, but to its side. This ball will not move up, due to oxidation.

Then, I can place the ball directly on the joint. It will transfer heat to the pin and the pad, and if there's solder on the pad, it will re-flow it. The ball can be moved using the tip up and down the pad, and also lifted off, so one single solder ball can maybe do 2-3 pins.

[xavier60]

There has been little mention of flux which is a must for SMD. I do a lot of production soldering down to SOIC and 0805 passives. I used to use the Hakko T18-S4, more recently the Hakko HT39-B02. Flux used is Caig RSF-R80-2.
With a new T18-S4 tip, I used to place it against the side of the IC pins. After some wear, I would switch to placing it directly against the pin.

[xavier60]

This is one possible way of applying the HT39-B02 tip. The next adjacent pins would normally be not yet soldered.
There would normally be a visible amount of flux between the pins.
I used to be able to get a new T18-S4 tip further in between the pins.

[David Hess]

I wipe the soldering iron tip immediately before applying it to the joint, so there is no excess solder and it is clean.

When I am done soldering, I never wipe the soldering tip before putting it in its stand.  Then the excess solder protects the tip from oxidation.

[xavier60]

By the way, while experimenting for writing the previous post, I figured out another way to use the tips, which seems to work, at least for QFP44 and similar packages.
Here are the steps:
First, I made sure that there's fresh flux on the PCB, and that the tackiness of the flux is holding the chip a little bit. A little bit of flat solder on the pads helps as well.
I cleaned the tip, and waited for a little bit, so it gets a little oxidized, but not too much. That's the key part.
While I have a little bit of oxides on the tip, I can add a little ball of solder near the tip of the tip, but to its side. This ball will not move up, due to oxidation.
(Attachment Link)
Then, I can place the ball directly on the joint. It will transfer heat to the pin and the pad, and if there's solder on the pad, it will re-flow it. The ball can be moved using the tip up and down the pad, and also lifted off, so one single solder ball can maybe do 2-3 pins.
(Attachment Link)

What diameter solder wire are you using? I have no trouble adding solder to the joint after the tip makes contact with the pin.
the pre-applied flux cleans the residual solder on the tip, improving its wettability and providing initial thermal contact.
The solder wire diameter shouild be no larger than 0.5mm.

[tooki]

However, I with conical tips, I always have the issue, that when they start out, they're OK:
(Attachment Link)
However, when I wet them with solder, the solder moves away from the tip a bit upwards, and then creates a ball, like here:
(Attachment Link)
After that, the tip of the iron is mostly dry. Therefore, when I try to initially make contact with a pin, heat isn't being transferred quickly, and when I try to add external solder, it also tends to first make a contact with the ball of solder and not flow down the tip towards the pin I'm trying to solder. The wider part of the tip is probably hotter than the narrower end of the tip, which would then make the solder flow there.
So are there conical tips, which tend to come with irons by default, all just bad design which doesn't want to die, or am I missing something?

Also, I used the 0.2 mm tip in this example, but in my experience, larger tip tend to have same issues.

Mercifully I haven’t had to do too much microsoldering that actually requires such a fine tip (for things like the ICs you showed later, you don’t need fine tips), but my old boss often does, and for those super fine tips, you have to crank the temperature up, way beyond what you need when using a normal tip. The thermal conductivity is just too poor to the point of the tip, since the thermal channel is narrow and only gets narrower, so the temperature at the thermocouple is significantly hotter than at the actual point of the fine tip. (Remember also that the iron plating over the copper core becomes a larger and larger percentage of the tip mass as you get to the point.) IIRC he’d use a 0.4mm tip at 400-450C, while “normal” soldering he would do at 350C.

[Ian.M]

+1
Long fine conical bits are essentially worthless, because of the lack of copper cross section area (CSA) to transfer heat from the shaft to the tip.  Maybe someone has a secret use for the like hand-soldering 0201 'flyshit' passives with low melting point solder, but they are worthless on a regular assembly, rework or repair bench.

Normal length fine conical bits are slightly more useful, though they still suffer from lack of copper CSA.  I wouldn't bother fitting one unless I was reworking fine pitch SMD ICs and 'flyshit' passives, to remove bridges etc.  They are useful  for soldering AWG 30 bodge wires to individual IC pins and passive end caps.

The only type of bit more useless than a long fine conical bit is a fine straight sided bit like this 1.0mm chisel tip abomination from Antex!  Again its lack of copper CSA, compounded by the low CSA thermal path length.  Its been 40 years since I attempted to use one but I still remember how useless it was. It wouldn't even solder two resistor leads to each other, as the component leads + the solder sucked the heat out of the tip faster than the heat could  make it down the thin part of the bit.  Fortunately it didn't curse my bench for long, as it was so thin and flimsy it tended to bend even with careful normal use, at the root of the thin section, cracking the plating and after a few hours the whole thin end dropped off as the copper core had oxidised through!

[AndrejaKo]

What diameter solder wire are you using? I have no trouble adding solder to the joint after the tip makes contact with the pin.

Interesting, I'm normally using 0.5 mm. I've also tried some 0.3, but I never managed to find a source of high quality 0.3, so I basically gave up on it.

Mercifully I haven’t had to do too much microsoldering that actually requires such a fine tip (for things like the ICs you showed later, you don’t need fine tips), but my old boss often does, and for those super fine tips, you have to crank the temperature up, way beyond what you need when using a normal tip. The thermal conductivity is just too poor to the point of the tip, since the thermal channel is narrow and only gets narrower, so the temperature at the thermocouple is significantly hotter than at the actual point of the fine tip. (Remember also that the iron plating over the copper core becomes a larger and larger percentage of the tip mass as you get to the point.) IIRC he’d use a 0.4mm tip at 400-450C, while “normal” soldering he would do at 350C.

Interesting! I'll have to experiment a bit with that. Normally, I tend to use 340C for some reason, so I'll give it a shot with higher temperatures.

[T3sl4co1l]

Yeah, I never got much use out of sharp conical tips myself.  Partly it may be that on the occasions I've used one, it was already well oxidized (implying I'm not the only one who doesn't know how to use them properly), but I've also had far better results from wedge style tips.

I do have a hook style tip on hand, when I'm doing fine soldering; fairly rare that I put it on, but there is the odd job where it works better than a wedge tip plus hot air.

Tim

[Wallace Gasiewicz]

The only use I have found for these pointy conical tips is poking holes in plastic.
They are pretty useless for soldering anything,

[Psi]

Another +1 for long fine conical bits are essentially worthless,

Chisel or Knife forever.

[xavier60]

What diameter solder wire are you using? I have no trouble adding solder to the joint after the tip makes contact with the pin.

Interesting, I'm normally using 0.5 mm. I've also tried some 0.3, but I never managed to find a source of high quality 0.3, so I basically gave up on it.

Oddly, I do have an old roll of 0.3mm solder that's next to useless. It mustn't have enough flux in it because when it touches the tip, it forms balls which just roll off rather than wetting to the tip. All of my 0.5mm solders work fine.
There is no great disadvantage in using conical tips for general purpose soldering down to fine work. Avoid unnecessarily long tips with small average cross-sections. 

[Psi]

There is no great disadvantage in using conical tips for general purpose soldering down to fine work. Avoid unnecessarily long tips with small average cross-sections.

I would disagree with the first part of this. However, as you say, it depends on how long and thin the conical tip is.
A short/stubby/thick conical is going to be night and day better than a long thin one.

Solder not sticking to the very end of the tip is solved by not having the tip, which is pretty much what a chisel tip is.

[xvr]

I once used that kind of tip to heat up IC pin to solder wire to it. There is no solder was on tip itself (all was on wire originaly). Pin spacing (0.5 mm) and pcb components density at this place made impossible to use more ordinary tip.

[SteveThackery]

Most liquids behave like this - it's something to do with surface tension, I think.  Anyway, molecular interactions.

This diagram shows what happens: the liquid is repelled by the sharp point (angle well over 180 degrees) but drawn into the corner (angle well under 180 degrees). Note that this happens even when the liquid wets the surface - oil on metal behaves like this.

[SteveThackery]

Forgive me, this is a massive deviation off topic, but I promise it's only one post. 😀

The jewelled bearings in watches use this phenomenon. In the diagram, the blue shaft (called an 'arbor') runs in the red jewels, and the bearing is filled with oil (not shown). The arbor has that sharp corner shown with the black arrow, which is there to prevent the oil from creeping along the arbor away from the bearing. It gets as far as the corner and then won't flow over it.

Just thought you'd like to know that!

[T3sl4co1l]

Good example!

Yeah, where the curvature is tighter than the natural surface tension for a given size of blob, liquid will be pulled away from that surface.  Doesn't mean there can't be a film over it still, but therein lies the problem: that film oxidizes through rapidly, and then the game is over.  You can clean it by removing the oxide, and immersing the tip in a large blob (without a free surface to pull solder towards, the tip will be covered as soon as flux dissolves the oxides), but you're back to the same problem minutes later.

The tight tip could help with dosing of solder joints -- by the same reasoning, solder can be drawn from the bulk of a joint, until the capillary forces balance, and this includes for bridges too.  But if it's not usable after the time spent between joints, it's not usable overall.

A wedge avoids this by being wettable on both sides of the corner, if not the corner itself; the curvature of a flat is zero, or for the mitered-cylinder style, the curvature of the cylinder is low enough to be easily wetted all the same.  The remaining corner, being a single line of poorly/un-wetted material, makes it a whole lot easier to clean, than the greater area of a sharp conical tip.  And as material inevitably dissolves or abrades away from use, the corner tends to be self-sharpening (whereas the sharp cone has way too much bulk to become sharpened in the same way).

Tim