Is it ok to use high temperatures with a low wattage soldering iron? - Page 1
Forum section: electronics / beginners

author: skillz21
author_rank: Frequent Contributor
timestamp: December 26, 2018, 05:56:56 am
content: I made the mistake of buying a 10-watt soldering iron. It has a temperature range of 100 - 450 degrees Celcius. The only problem is when I set the temp to 350, it is difficult to solder things with a large thermal mass. Setting the temperature to the maximum 450 makes things a little bit easier. My question is, is it okay for me to do this? Will this damage any components? Will this damage the iron itself?

author: Brumby
author_rank: Unknown
timestamp: December 26, 2018, 07:30:58 am
content: This is the problem with purchasing under-powered equipment - whether soldering irons, electric drills or motor vehicles. You can make them work ... to a degree ... but there will always be risks - usually in damaging the item and/or a poor job.In the case of a soldering iron, large masses need a lot ofheatin order for the temperature to increase to melt solder. With a decently powered iron, the iron's temperature only needs to be slightly higher, as it can continue to provide heat until the parts to be joined reach the necessary temperature.With a lower powered iron set at the "proper" temperature, the heat it provides is nowhere near enough - and the only way to increase the heat it generates is to push up the temperature. This is a common practice - but the wider the gap between the capabilities of the iron and the needs of the joint, the harder the iron has to work which may well shorten its life because the actual heating element will need to reach a higher temperature than the tip temperature.Aside from that, you will have to be careful about application of solder and flux. If the flux is exposed to the high temperature of the iron, it will immediately evaporate. However, the bigger risk will be if the high temperature of the iron heats components excessively. This can be through the temperatureon the componentbeing too high and/or the heat being applied fortoolong. The length of time is the the most common issue - just heating and heating and heating the joint until it reaches the necessary temperature. This can - and does - kill devices, not to mention PCB pads and tracks.. You will often see soldering information on datasheets - and for hand soldering it is not uncommon to see a limit of 300ºC for 10 seconds.Yes, it can be done - and has probably been done (to varying degrees) by most everyone here at one time or another ... but a 10W iron on a ground plane without any assistance is something that is going to be an extreme challenge.

author: skillz21
author_rank: Frequent Contributor
timestamp: December 26, 2018, 07:39:09 am
content: So what do you think is a good temperature to set my soldering iron to for general soldering? 400 degrees?

author: EEVblog
author_rank: Unknown
timestamp: December 26, 2018, 08:36:33 am
content: Quote from: skillz21 on December 26, 2018, 07:39:09 amFro a 10W iron and a decent large tip you should be able to get away with lower than that, 350C is common.But it's all highly dependent upon the type of tip, construction of tip, tip plating, tip-heater coupling mechanism, and the power and sensing response system.The high temperature is more of a problem for very small pad surface mount parts, as you can lift the adhesive on the copper pad if not careful. And more a problem for rework than soldering.

author: David Hess
author_rank: Super Contributor
timestamp: December 26, 2018, 11:08:13 am
content: Even on a more powerful soldering iron, it helps to use the largest tip possible for greater heat capacity when soldering larger junctions.Raising the tip temperature because insufficient heat capacity is available is almost always a bad idea because of inconsistent temperature on different joints which risks frying smaller joints.

author: vidarr
author_rank: Frequent Contributor
timestamp: December 26, 2018, 11:37:24 am
content: I have not done this, but I have seen someone else add mass to the soldering iron to hold heat better. I think it was something he bought for this. If you cannot find this type of item, I think you could probably figure something out. He also closed the gap between the metal tube and the handle.

author: soldar
author_rank: Super Contributor
timestamp: December 26, 2018, 01:08:32 pm
content: IMHO 10W is woefully undersized for normal work with components. 10W with a tiny tip would be adequate for SMD and other tiny components.OTOH, I have never had any fancy soldering irons with adjustable temperature and I have worked fine. A fancy, expensive soldering iron is not going to make up for bad technique. I have about eight soldering irons and they are all of the cheap kind and work just fine. I consider them disposable and yet they last many years. I have no idea what is their temperature. If I am going to solder a big chunky part with a smaller size iron I will wait a bit until it accumulates some heat. If the iron has been sitting in its holder for a while and is presumably very hot I might blow on it to cool it down a bit before applying it to the work.Off the top of my head I believe the smallest one may be 15 or 20 watt and the largest maybe 100 or 120. If I need to solder bigger parts I may use a blowtorch.Generally I would rather go with an oversized iron and just be careful not to apply it for too long if the parts can be damaged.For a while some years ago I had a setup where putting the iron on its resting holder would activate a switch that would insert a diode in series so the iron could be at rest without getting too hot. It worked but I did not find the need to do it again later.Cheap soldering irons are dirt cheap. Get yourself 20, 40, 80 watt irons and use the one most adequate for the work you will be doing. Trying to use the wrong iron can only result in poor work, cold joints, etc.

author: GreyWoolfe
author_rank: Unknown
timestamp: December 26, 2018, 11:16:16 pm
content: Quote from: soldar on December 26, 2018, 01:08:32 pmOn the flip side, good technique will not make up for inadequate equipment. I learned to solder with cheap firesticks. Thankfully, now I have very good quipment. My soldering is done at 650F but contact is no more than 3-4 seconds. I get proper, quality, shiny joints like that. I understand that some datasheets may say 300C for no more than 10 seconds but that seems like an eternity to me.Quote from: soldar on December 26, 2018, 01:08:32 pmNo offence, soldar, but I just can't wrap my mind around the just buy cheap mindset. Cheap isn't good and good isn't cheap. Unless there is a dire need, save up until one can afford proper equipment, especially if you are going to do a lot of soldering. It took me quite a while to get to the equipment that I have. It is so much better having equipment better than my skills than the other way around. The one lesson my dearly departed Dad drove into me time and again is to buy the right tool and buy it once. I still have some of his hand tools that are over 60 years old and I use them regularly.

author: Jwillis
author_rank: Super Contributor
timestamp: December 27, 2018, 03:39:22 am
content: Theirs a difference between Heat and Power.The heat or temperature that required to melt the solder is typically between 180 and 190 °C (360 and 370 °F) . The power or Watt is a unit of power, defined as the rate of energy transferred per second.So a lower wattage iron will take more time to heat something than a higher wattage iron.This slow heating is what damages the component because the whole component sinks the heat away before the solder melts.You also have to consider that the trace and board will transfer heat away as well .A higher wattage iron will heat at a more localized point faster, melting the solder before the heat transfers into the component ,trace and board .Essentially the power rating in Watts is how well the iron can sustain the temperature against heat being transferred away. Using bigger tips is fine but can be difficult when components are very small.To high a temperature isn't a good thing either because you risk changing the characteristics of the copper (annealing ranges from 260 °C (500 °F) to 760 °C (1400 °F) depending on the alloy) and potentially destroying the epoxy holding the traces to the board.The strength of epoxy adhesives is degraded at temperatures above 350 °F (177 °C) on FR-4 copper clad.Although higher temperature copper clad exists FR-4 is the most popular.Typically 60 Watts and higher for Pen style irons is best for electronic components and a 260 Watt gun for soldering to chassis and very large connections.

author: james_s
author_rank: Super Contributor
timestamp: December 27, 2018, 06:05:19 am
content: You don't have to spend big bucks on a top end Pace or Metcal, but don't buy cheap garbage either. Unless you are on an extremely tight budget, buy a Hakko, or if you really can't afford ~$100 look at the reviews for some of the ~$50 Chinese soldering stations, at the bare minimum get something with proper thermostatic temperature control that can put out at least 60W.I used a 25 and 40W firestick for years when I was a kid and real soldering stations cost hundreds but these days decent gear is so cheap there's no reason to go with the absolute bottom of the barrel.