Soldering iron buying choice: watt vs. temperature? - Page 1
Forum section: electronics / beginners

author: analogix
author_rank: Frequent Contributor
timestamp: December 06, 2017, 01:51:58 pm
content: Recently I've been running into unexpected problems when soldering (cold joints etc.) and wonder if my trusty old Japanese 25W Goot soldering iron has reached its end-of-life after a couple of decades (or more) use. I've changed its tip but that didn't help. To further confuse matters I had to buy a new roll of solder, but being quality branded(Multicore/Loctite) 0.71mm 60/40 leadedI don't think that's it (unfortunately the labelling of my old solder has long since gone).I'm a hobbyist (building kits or solder ready made PCBs, all through-hole so far), soldering a bit now and then, and although I did consider a soldering station at some stage I'm leaning more towards a new quality soldering iron as I just can't justify the costs for something I don't use very often. And I don't like buying cheap stuff which breaks and needs to be thrown away after a little use either. So I'm looking into another Goot soldering iron, this time aPX-201 temperature adjustable (250-450 C) 70W typecostingaround US$ 43 plus shipping. There are also around 20 replacement tips to be found for it.Hakko has a similar type (FX-600)but it's (not surprisingly with that brand) more expensive.What confuses me is the relationship between temperature and wattage in soldering irons. I always thought that for delicate electronic components you'd need a low wattage soldering iron around 20-30W, and for more durable stuff and where heat is quickly dissipated (wires, grounding planes etc.) a higher wattage was needed. But then I read somewhere that the amount of watts has to do with how quickly the soldering iron can regain heat when having lost a lot (i.e. soldering something to a large ground plane), and that the temperature adjustment has to do with its application (lower for electronic components on PCBs, higher for cables, connectors etc.)Is this correct, and will this type of adjustable soldering iron be suitable for the same type of work as before (through-hole soldering of resistors, capacitors, transistors, ICs etc. to PCBs as well as wires, cables etc)?And is such a soldering iron something similar to, but not quite, a soldering station with its temperature adjustment?

author: sstepane
author_rank: Regular Contributor
timestamp: December 06, 2017, 02:35:52 pm
content: Hi there,I think You're looking for temperature recovery time. I don't know about Hakko mentioned, but this Goot iron is quite good since its heat up time is approx. 30-45 seconds (as far as I remember) which is better than usual chinese irons, but far too long compared to Hakko T12 or JBC, Ersa, Metcal (3 to 12 seconds). Best recovery times are in irons mentioned and it comes with price. But if You do soldering all the time - these, in price 10 times more than 45 usd are worth every penny.As for wattage, I think 70W will fit most needs in electronics.

author: Brumby
author_rank: Unknown
timestamp: December 06, 2017, 02:38:12 pm
content: This is the key bit of information:Quote from: analogix on December 06, 2017, 01:51:58 pmEverything else descends from that - plus a thing called "thermal mass".Greater thermal mass allows an iron to lose heat at a lesser rate, which means temperature drop will be slower. Unfortunately, this requires physical bulk - and that's just not always convenient.The answer to not having the temperature drop too far is to have greater power which can put more heat in and help keep the temperature up ... BUT there is a problem with this. Left to its own devices the temperature will rise to levels that create a risk of cooking components and boards, so the way to address this is to have a system where the power is controlled to maintain a steady temperature. This is where we end up with temperature controlled soldering stations.But that isn't the end of the considerations...Temperature control systems must have a point where the temperature is measured - and you will be hard pressed to find one that does that at the actual solder joint where it matters. In most (affordable) systems, the temperature sensor will be closer to the element than the tip - which means there is going to be a temperature difference from what the sensor is registering and what the actual temperature of the puddle of solder around the tip. This can be mitigated by good thermal contact between the element, sensor and tip - plus greater thermal mass in this region.The better units will have more refined design of the whole element/sensor/tip structure to keep the temperature differences to a minimum, which will also result in smaller temperature fluctuations. How well they do this - and for the range of scenarios from SMD to ground plane metalwork - is usually reflected in the price.Choosing the one that's best for you is then the challenge.

author: jgalak
author_rank: Regular Contributor
timestamp: December 06, 2017, 03:31:19 pm
content: I have an older Chinese temp controlled soldering station (Aoyue 2901). It was my first controlled iron - before that, I always used the cheap pencils. What a difference! But then I got a chance to use a friend's Hakko. Blows it away, for exactly the reason mentioned - temp recovery time is shorter, so it's much faster to use.The Aoyue, I have to pause, momentarily, to allow it to heat back up - especially after cleaning the tip. The Hakko just worked.I'm used to the Aouye, and it works acceptable, so I'll probably keep using it until it dies, but after that, I'm shelling out the money for Hakko. Kind of wish I'd gotten it in the first place - my advice is to get the Hakko if you can afford it.

author: kalel
author_rank: Frequent Contributor
timestamp: December 06, 2017, 07:56:49 pm
content: Quote from: jgalak on December 06, 2017, 03:31:19 pmI would recommend trying to clean the tip with one of those brass shaving type of cleaners, using a twisting motion it is usually very easy. I can't say if it's better than the sponge (or when following up with the sponge) but it's the easiest method by far, since you don't need to add water. It should not take much heat away from the soldering iron at all, so you may not have the recovery issue.

author: analogix
author_rank: Frequent Contributor
timestamp: December 06, 2017, 08:22:02 pm
content: Quote from: jgalak on December 06, 2017, 03:31:19 pmAre you referring to Hakko solderingstations, or that FX-600 adjustable temperature solderingiron?Like I said, I really just can't justify (at least not at the moment) a complete soldering station mainly because of the cost, but also the extra bulk/storage space it demands. I figure that since I've gotten by with a normal soldering iron for so many years I can do fine with a similar (but slightly more powerful) soldering iron.As for the Hakko FX-600 I just haven't come across any dealers anywhere selling a European 220/240V version.sstepane: Where did you read about the fast heatup time? For what I'm used to, waiting 3-5 minutes before being able to solder is no problem, so that's not an issue at all. I've been using a 25W Goot CS-30 (an older version of theGoot CS-31) up to now, which has for the most part done the job (a little weak for soldering larger surfaces) but for some reason doesn't work that well any longer. This is what I'll be comparing a replacement with. So you're saying 70W should be able to handle everything I've used the 25W iron for as well as soldering bigger surfaces?Brumby: Do you think the temperature control of this particular iron is to be trusted?If it doesn't measure the actual tip temperature I don't mind, as long as it measures consistently from somewhere else. I really have no idea what to set the temperature dial at for "normal" PCB/component soldering for instance, so I would just set it at a low setting, then go up from there until it melts the solder sufficiently and take a note of that. Or have I misunderstood what you're saying? I take it that a good soldering station with a digital readout actually outputs 250C at the tip when it says 250C on the display.But regarding the wattage, do I understand it correctly that this 70W iron is suitable for delicate work (through hole, or even SMD components to PCBs) when the temperature dial is set to a low temperature, and at the same time being suitable for soldering larger surfaces, cables etc. when the temperature dial is cranked up for a higher temperature?

author: analogix
author_rank: Frequent Contributor
timestamp: December 06, 2017, 08:38:28 pm
content: Quote from: kalel on December 06, 2017, 07:56:49 pmI got myselfa sturdy Velleman standwith one of those brass cleaners for the reason above (not needing to add water) but mostly because I've read that a sponge "shocks" a soldering iron tip, thereby shortening its life.But how about the abrasive effect this has to a soldering iron tip? Won't cleaning it this way scratch away the outer layer?

author: sstepane
author_rank: Regular Contributor
timestamp: December 06, 2017, 08:52:28 pm
content: Quote from: analogix on December 06, 2017, 08:22:02 pmProblem is not with waiting for it to heat up (but it is another factor that says how quick the response is), but how fast the iron will restore its hot end temperature. This is quite a problem when soldering small smd element onto big pad - small iron tip just sticks to the pad and cannot heat it up.70W is the minimum recommended for lead free soldering, which is a standard now.For the wattage and low-high temperatures for soldering small and large surfaces - higher temperature is cranked because the iron cannot heat it up quick enough (heat response).High end stations do solder at any set temperature and are able to heat up quite a big surface with tiny tip.BTW, You may want to consider getting DYI kit for Hakko T12 tips along with tips (original tips are better, but there are good copies). In my country it is number 1 selling soldering station - very good performance for the price.While PX-201 is a good soldering iron - it is huge and quite long compared to T12 or Goot RX802AS which are more like a big pencil but with the same power and, what counts as well - very easy on the fly tip change.

author: jgalak
author_rank: Regular Contributor
timestamp: December 06, 2017, 09:52:24 pm
content: Quote from: analogix on December 06, 2017, 08:22:02 pmSorry, misunderstood. Station. I've not tried the FX-600. I understand cost/space constraints, but if you've not used a station, you really should. Even a cheaper chinese one blows any regular iron out of the water (again, don't know about the FX600).The problem with regular irons is that 25W or less just don't keep hot enough, and 40W or more will get too hot without regulation and damage sensitive components.

author: jgalak
author_rank: Regular Contributor
timestamp: December 06, 2017, 09:54:00 pm
content: Quote from: kalel on December 06, 2017, 07:56:49 pmI actually keep both on the bench (I have a holder that has them both). I find the wet sponge better when first getting the iron ready and every now and then as I'm working and it gets gunked up, and the brass works better to get stuff off the iron between each component. Having both is very nice.

author: GreyWoolfe
author_rank: Unknown
timestamp: December 06, 2017, 09:54:56 pm
content: Quote from: analogix on December 06, 2017, 08:38:28 pmThe brass wool should not have an effect on the tips, brass is a softer metal. As I saw in video, don't push the tip in and out. Push in and twirl the tip to clean it. I switched from the sponge to the brass curls when I got my Hakko FX-951 a couple of years ago. I won't go back to a sponge.

author: kalel
author_rank: Frequent Contributor
timestamp: December 06, 2017, 10:24:00 pm
content: I don't know if either the sponge or brass will damage the tip significantly. I assume it would be easier to damage it by not cleaning at all.

author: analogix
author_rank: Frequent Contributor
timestamp: December 06, 2017, 11:09:48 pm
content: This talk about sponge and brass wool got me thinking that the tips might be oxydized, despite being quite new and looking OK. It makes sense since solder doesn't "flow" out to the tip, but melts in a blog which doesn't stick to the tip. And I'm no longer able to create silky-smooth solder joints as before. Does this sound like an oxydized tip, a failing soldering iron or the wrong type of solder? As I mentioned before I did get some new solder (60/40 as I assume my lead-based solder from before had the same mixture), but I read something about different melting temperatures for different solder. Maybe that's it.But back to the (possibly) oxydized tip: I read that you should use fine sandpaper to remove the dirt from the tip, then melt some solder on to it which you let stay there for a little while. But in other places (soldering iron/station manufacturer's pages I believe) they say you should avoid scratching the tip. GreyWoolfe: as you pointed out that brass is a soft type of metal, and thinking about it I've already tried cleaning the tip by twisting the soldering iron into the brass wool (askalelsuggested earlier in this thread), but to no avail. I've heard there's some sort of chemical paste or liquid to use in order to "renew" the tip, but I'm unsure of what it is. Does anyone know?... or maybe it's just that the soldering iron has reached its end of life as I mentioned initially.Yes, I did notice from the specs that the Goot PX-201 was a bit on the large side (210mm vs. 170mm of my current soldering iron) which might be an issue. The specs for the Hakko FX-600 says 233mm which is strange as it appears more compact than the Goot PX-201, but nevertheless I haven't found a single place where the 220V model is sold (apart from eBay and the likes of course.... if you're happy risking getting a fake one).

author: kalel
author_rank: Frequent Contributor
timestamp: December 06, 2017, 11:29:16 pm
content: Could you show us an image?Sure that some oxides cannot be seen, but if it looks shiny at the end (after cleaning it), most likely it's fine. Some videos mention that the inside of the barrel could be slightly oxidized, and could be cleaned with some brush. You normally shouldn't need to use anything that scratches the tip. After a while, of course, heater can be the problem as well.After each use, it is good to clean, then apply some solder and keep it there. You could do it right after unplugging the iron. Then, oxidation will have to go through the solder first before it can cause any damage.Also, it is good to unplug the iron (and do the clean/apply solder thing) each time the iron is not going to be used for longer than a few minutes. If you have to do it many times and there is no switch, that can be annoying. Still, it will help everything to work longer. Depending on the iron, it might be wise to take a break after each x minutes and unplug it for a little bit.I should mention that I don't own any expensive not made in China iron. Only with one really cheap one I had a problem after a couple of years of really occasional use. In my case, it was most likely the heater. I used to have problems with tips until I started doing the tinning (applying solder) after each use and using either the sponge or brass shavings to do the cleaning. After doing that, all tips seem to last much longer, including the really cheap ones.

author: soubitos
author_rank: Frequent Contributor
timestamp: December 07, 2017, 12:10:24 am
content: I used to have a sub-20W ANTEX which served me well while in technical school and for what i was soldering back in the day.For "heavier" work i had a soldering gun i think 60-70W no more... I also got various el-cheapo chinese irons over the years which sooner or later died on me or i through them away.. some i even paid for!!Two years ago i went to shop for a new soldering iron and i got myself a top brand (ERSA) MULTITIP 25W for some 30 euros.I quickly found out that i needed a different tip but for 10 euro a tip i didnt buy one... the one that came with the iron did not satisfy me at all though and it started taking solder not only in the tip but all over the surface after a few months of relatively light use.I searched for a solution and decided to gamble with a Chinese TS100 as a lot of people praised it....I use it with a 19,5v/4,5A laptop power supply and again i found the need to buy a second tip.. only this one has tips with embedded heating element... i got one for 9$ delivered!!!! (that was ERSA it would cost 15-20 euros when they charge 10 euro for a simple tip!!!The tip that came with TS100 is now in storage and despite the fact that i use it heavily for several months now, is as good as new. The new one i got only a couple weeks but immediately improved my soldering/desoldering even on smd stuff.Now, smd mentioned, i also got myself a 858D hot air station which is simply amazing for 37$ delivered from Germany (got it on 11/11)...My opinion for any hobbyist, TS100 is a honest, reliable and proven concept, its not dirt cheap but it is worth every cent you spend on it and does the job very very well... but if you want to work with SMD you really need a hot air station and it can be really cheap these days

author: Brumby
author_rank: Unknown
timestamp: December 07, 2017, 01:02:09 am
content: Quote from: analogix on December 06, 2017, 08:22:02 pmI can't answer that from personal experience. Sorry.QuoteThat is actually one of the problems. There is a temperature gradient between the sensor and the solder puddle - and it is dependent on how good the thermal coupling is in this region (as mentioned before) and how much heat is being drawn. From just sitting in the stand, to soldering an SMD resistor, to soldering a metal tab to a ground plane, the heat flow increases and so does the difference between what the sensor is measuring and what the temperature of solder puddle actually is. This difference is due to the construction of the iron and unless the sensor is something like a thermocouple you stick into the solder puddle, there will always be a difference - and that differencewillchangedepending on the amount of heat flowing. What only ever matters is the actual temperature of the solder puddle.You might get a better feel for things if you look at what is happening as a thermal resistance exercise - with the element being analogous to the die in a transistor, the joint analogous to the heatsink with all the intermediate boundaries that exist (element/barrel/tip/solder/joint/ambient as a minimum) and paying particular attention to where the temperature is being measured by the sensor.QuoteWe all go through a 'familiarisation' stage when we get a new iron - so what you are saying here is pretty normal thinking. After a time, you will get to know how your iron deals with different jobs and how to adjust it to perform properly in different situations.QuoteThat is an "ideal" soldering station. There will always be a temperature drop - especially during soldering - but the really good stations will have a more accurate control system.QuoteThis is where the "ideal" gives way to the real world.A 70W iron doing SMD is not too far from the ideal. You set a temperature and because there is not a lot of mass to suck away heat, the actual temperature is not too far away. As such, you set the temperature closer to the actual melting point of your solder and the temperature control system is switching the element on and off to keep it there.However, when you are soldering heavier joints, there is a lot of heat getting sucked out - so you need more heat in. Setting your iron to the same temperature as you would for SMD means that the temperature at the tip would drop very quickly and the temperature control circuitry would switch on when the sensor dropped below the set point. What happens next is important...Once the element is turned on, it heats up, then it's surrounds heat up, the sensor heats up and eventually the tip heats up - followed by the solder. The temperature control system monitors the sensor - so when thesensorreaches the set point, the control system switches off the element. The problem with this is, that the tip and the solder haven't been heated up enough - because the joint is sucking away heat big time.The simple response to this is to do exactly what you have said - crank up the temperature. This allows the element to be kept on long enough to deliver the heat required to get the solder and joint up to temperature. The risk is thatyounow have to take responsibility for the actual temperature at the joint - something that will come only with experience.

author: Audioguru
author_rank: Super Contributor
timestamp: December 07, 2017, 01:22:39 am
content: Some cheap soldering "stations" use a simple light dimmer circuit for you to adjust the power but not the temperature. They get too cool while soldering and get too hot when not soldering then the next solder joint is with the flux incinerated, a poor solder joint and the tip burnt.You need a soldering station with temperature control and you probably never need to adjust anything. My Weller soldering iron has its tip always at the correct temperature.

author: KL27x
author_rank: Super Contributor
timestamp: December 07, 2017, 11:12:11 am
content: QuoteIt sounds like the iron is truly thermostatic. It is decribed as temp-controlled. And furthermore that it has a temperature sensor (i.e. feedback). So I would hope it is not just a variable power iron.If it is a temp-controlled iron, and if the response time is fast enough, and if it is truly 70W, then you shouldn't have to change the temp dial much, at all, going from delicate things to fairly larger things. (Tip changes maybe more important than temp changes). But as others have already stated, response time is one factor. Another factor, which is often overlooked is the fact that power ratings are somewhat... flexible.For instance, Hakko 888 is listed at 65W. I have measured resistance of the heater when cold and when hot. I have recorded voltage over time, with heater switched on/off. Cold and hot. And IMO, 65W is a remarkably moderate power rating. This is truly close to the actual power drawn when at soldering temp. (And I was completely shocked to see how stable the transformer is in this station.) When Goot says 70W, that could mean something else entirely. It could be 70W max, when the heater is cold. But then it could drop to 30W after it warms up, due to heater resistance increasing with temperature. And that would not be lying.And this doesn't even take into account where that power goes. Some irons are better at putting that power into heating the tip. Others are better at heating up your hand.

author: analogix
author_rank: Frequent Contributor
timestamp: December 15, 2017, 01:16:22 pm
content: Quote from: kalel on December 06, 2017, 11:29:16 pmSounds right to me. Sorry, I don't have an image but I think I've figured out the problem (or should I say problems)..First of all, even though the tip looked shiny I applied a lot of new solder to it and let it stay there. I've done this in the past, only to see that the melted solder didn't stay all over the tip but concentrates in one area. I suppose this is the effect of oxydization? So this time I carefully rolled the soldering iron around which effectively forced the melted solder to stay in several different places for a few seconds.The other thing I did was buy aWeller tip activatorand dip the hot soldering iron tip into that paste (also rolling it around to throroughly clean the whole tip). I tried tinning some wire ends after that and it appeared fine, as well as some other basic soldering.Then I picked up the PCBs I was working on previously, only to experience the same problems as before. It occured to me that unlike my past projects, these PCBs were very densely populated (designed by a friend of mine using the CAD software Eagle, staying inside the size limitations of it and the PCB-fabrication company we used for cost-effectiveness) and it appears the component holes are also smaller than what I'm used to in the past. I think part of what has made previous soldering sessions successful is the capillary action, but with these PCBs it doesn't seem to work that well, even when letting the soldering iron tip stay at the joint for a little while (to heat it up), the applying just enough solder and allow it to melt before removing the soldering iron from that area. The result? A "blob" of solder a little above the PCB, attached to the component's leg. I'd say a partly cold solder joint as opposed to a nice, shiny, clean soldering joint. So it's probably my technique which needs some refining.Finally, I realized that with this project I've been re-using a lot of components which were previously soldered to other PCBs of mine, so that might have contributed to the problems.QuoteHmmm... so the solder stays on the tip after it cools down? I've always taken care to clean the tip thoroughly (in both a moist sponge and more recently also in combination with brass shavings) before unplugging it. I'll try your suggestion.QuoteWith my 25W Goot soldering iron I've been soldering for 1-2 hours (with breaks in between) without unplugging, and it caused no problems. I did however buy a cheap Chinese desoldering iron, and although I consider it one of the wisest tool purchases I've made (it's made desoldering so much easier and quicker) it gets gradually hotter as I keep it plugged in, so after a short while (15-20 minutes IIRC) I have to unplug it.But unplugging the soldering iron during those breaks might be a good idea for the sake of making it last longer I suppose.QuoteI'll definitely give that a go (actually I'm soldering as I'm writing this, and have just tinned and unplugged the iron). The work flow will be opposite of before then: I start by cleaning the iron, but that's really no problem.

author: kalel
author_rank: Frequent Contributor
timestamp: December 15, 2017, 02:01:22 pm
content: Regarding the tinning after soldering, so that solder will remain on the soldering iron tip after unplugging, I do recommend that. You do have to clean that solder off the next time you use it, but some will recommend to clean before using anyway. If you are soldering old and/or reused components, they might be slightly oxidized too, and if you had something to scrape the leads with slightly before reusing the component (some abrasive paper or otherwise) - and the time to do that - a quick scrape might remove some of the oxides, making things easier to solder. I haven't done that myself yet, so I'm not sure what kind of abrasive thing (paper, precision file, etc) is best for the task.You can also consider adding some additional flux. Cheap flux pens do work, as do those cheap "paste" fluxes. I heard liquid ones work too. I can't recommend a "good flux" as I don't have experience with a variety of them, but any should help (I heard that some can cause too much corrosion, but any intended for electronics should be fine). There's also a ton of threads here about them.As for turning off or unplugging the iron during any breaks, that is important with fixed power (or manually controllable power) irons that do not have any heat regulation built in. Your Goot might have it, so that shouldn't be as much of an issue. That's possibly also one more reason it lasts longer than the really cheap ones, better heater but also less overheating. Although I've heard that some temperature regulated stations will lower the power when the iron is not in use, so it might be wise to unplug anyway if not using for a while.

author: sstepane
author_rank: Regular Contributor
timestamp: December 15, 2017, 02:30:05 pm
content: Quote from: kalel on December 15, 2017, 02:01:22 pmFrom stations I've used - JBC CD series lowers iron temperature to 150C (can be set) right after you place iron in the stand, GOOT RX-802AS (and higher versions) have sleep mode (can be set in minutes and what temperature to keep while sleeping), pretty sure Ersa icon series do the same, not sure if it has delay or do as JBC. From this point of view - JBC is the best in this regard, as the iron on full temperature only while it is in your hand. However, it heats up in just 3 seconds, Goot heats up in about 6 seconds, so it is quite reasonable and longer the tip life.

author: analogix
author_rank: Frequent Contributor
timestamp: December 15, 2017, 07:26:53 pm
content: Kalel: I'm pretty sure there's no electronics at all inside my Goot soldering irons. They're from way back in the mid-80s but still going strong apparently. Especially after cleaning the tip properlyI'll keep in mind to unplug it whenever I take breaks from soldering. The Goot PX-201 probably has some sort of circuitry inside, judging from the much more it costs than "basic" solder irons and the fact that it allows adjusting the temperature. Now that I've figured out the soldering problem I'll see how long I can last with my existing soldering irons (I believe one is 20W and the other 25W -a little on the weak side I think, even for electronic components, right?) until I possibly order the PX-201 or something similar. There are soldering stations in the same price-range as that PX-201, like those red Weller units, but I hear they're crap (and nothing like their "professional" blue soldering stations) and honestly I think I'd be better off with a high quality soldering iron then.Yes, I should probably have cleaned those used components before re-soldering them, but didn't think much about it at the time. I did buy a fibreglass pen recently which I think might be useful for that sort of thing. Regarding flux: to be honest I don't have any experience in using it, until recently (after having been suggested in another thread to use it) when I was wrongly informed in the store and ended up with an acidic type of flux (intended for plumbers I think). I haven't been able to find something suitable for electronics locally but I'll see what I can get online. I suppose I should stay away from the eBay stuff as you never know what you're getting. I'll look through the threads here and see what info I can pick up on the subject.