We take a look at a very compact, mid-level version of this workbench essential.

As far as Maker workbenches are concerned, very few are complete without some way to solder. Depending on specific interests and fields, some Makers rely on a hand-held iron only. However, most Makers will end up with a soldering station as one of their earlier 'big equipment' purchases. Without the budget of research and development labs, few makers go straight for the most expensive professional option. One trade-oriented supplier we use lists a soldering station at over $2700!

The reality for most Makers is that they will buy a soldering station on a budget of some sort, from a retailer rather than a trade supplier. They therefore must choose some criteria to guide their purchase, and decide what features make one soldering station better than another, for their own purposes and context. This fact may be obvious to some, particularly those who have done this several times. Many others, however, do not understand why there may be three different stations in a similar price range, or such a big price range between top and bottom.

The existence of this variety and its effects are necessary to understand as we look at the T2040 Micron Compact Soldering Station from Altronics. Whether or not it is a 'good' station for a Maker to buy depends on whether that Maker's needs match what this station offers, at the quality and price offered. So, it would not be fair of us to make broad, sweeping statements like, 'everyone should have one', because everyone's needs are different. That fact makes it a bit harder to show how impressed we were.

MODEL	T2090	T2040	T2460A
Heating Element	40W	68W	100W
Temperature Range	150°C to 450°C	80°C to 480°C	100°C to 500°C
Temperature Adjustment:	Graduated Dial	Dial with LED display	LCD with pushbuttons
Preset Temperature Memories	No	No	Yes, 3
Tip Sizes	0.5mm and 1mm conical, 2mm and 3mm chisel	0.5mm conical, 1.2mm and 2.4mm chisel	0.2mm and 0.8mm Connical, 1.6mm and 3.2mm chisel, 2mm Mini Wave
Tip Price *	$10.50	$14.50	$12.50 to $27.75
Lead-Free	Yes	Yes	Yes
Stand	Integrated	Integrated	Stand-Alone
Tip Cleaner	Sponge	Sponge	Brass Wool
ESD Safe:	Not Stated	Yes	Yes
Price *	$65	$125	$375
Additional Features:		Temp sensing stand with auto standby and shutdown; solder reel holder; temp lock button.

* RRP correct at time of printing, excludes specials

THE MICRON T2040

The Micron T2040 is a compact, dial-adjusted lead-free-capable soldering iron, which sits somewhere in the middle of the scale. At the top of the scale from Altronics is the T2460A, a soldering station that we use here on the DIYODE workbench. At the entry-level end, is the T2090 Economy soldering station. It seems fair and practical, then, to compare the T2040 to both of those. We do not have one of the economy irons, so we'll compare specifications and published data there.

The T2040's most obvious feature is its compact footprint. The soldering pencil holder is mounted above the power supply and control enclosure, with the temperature control dial on the front sloping face. That gives a footprint of 130mm x 70mm.

It does cheat a little to achieve this, with the tip cleaning sponge being located on the separate solder reel holder rather than the soldering station itself.

Inside the pencil holder, hidden behind the shell, is a sensor of undisclosed variety, which monitors the pencil. We are unsure if it is a temperature sensor or some form of proximity sensor. Either way, if the pencil is unused for ten minutes, the control unit automatically bumps the tip temperature down to a standby temperature, which is safer for the tip to be left at. After twenty minutes, full power-off occurs. Powering the iron on again is achieved by adjusting the temperature control.

This feature on the T2040 and other irons as well can be annoying at times, and can even seem like a bad idea. Tips add up in cost when you have to replace them too early, too often, and a mildly damaged tip affects the quality of the soldering done. That is, until you have destroyed a tip or two, or even caused melt damage or fire, by leaving your iron on. The iron itself is unlikely to catch fire (though it is documented), but when positioned too close to, or under, other equipment, fire can result. These problems are the origin of our soldering iron alarm in Issue 42.

While the T2040 does not have a set of preset temperature memories, it does have a lock button. This is also the °C/°F button which, when pressed and held for three seconds, enters the selected set temperature into memory, and any further adjustment of the temperature dial is ignored. This would make the auto shutdown feature less annoying to use, too, if you can turn the dial to wake up the station without actually changing the temperature. Exiting lock mode is done by pressing the button again for three seconds. The temperature lock uses non-volatile memory, so the locked temperature is retained after power is turned off. So, even if you have a crowded workbench where the dial is likely to be bumped or otherwise accidentally changed, your iron will always turn on to the same set temperature.

The T2040 comes with a solder reel holder, which is a less than universal inclusion. Many soldering stations have a separate holder for the pencil, and do not bother adding any way to hold solder. This is a nice touch, and the total footprint is still quite compact. The control/power supply unit has a rack built into the back of the pencil recess to hold spare or different tips as well, which is also unusual. Often, on the occasion that such a storage capacity is provided at all, it is just a tray.

COMPARE THE PAIR

Seeing as we have a T2460A as part of our permanent equipment, we'll note a few similarities and differences between the two, to illustrate why the prices are so different. That does not necessarily mean one is better than the other, as noted above. That determination is decided by your circumstances, needs, and preferences.

The most visible difference is the size. Even with the solder reel holder, the T2040 takes up much less space. The bigger display of the T2460A allows display of both set and actual temperature, but it is a touch-screen LCD. The LED display of the T2040 displays only one temperature at a time, but is easier to see in varied lighting conditions and will likely last longer, too. However, both will probably outlast the soldering pencil.

On that note, the soldering pencil is fixed into the T2040, and has a thicker and less supple cord than the T2460A. However, it is still easily flexible enough to be comfortable and far more flexible than most leads on mains-powered irons. The pencil on the larger station is connected via a four-pin screw-in connector. While this means the pencil can be easily replaced on the T2460A, a spare is not listed. Instead, it supports interchangeability with an SMD soldering tweezer pencil available as an optional extra.

The other difference that is not visible is that, while both irons are ESD-safe, the T2460A has a 4mm banana socket at the back, while the T2040 relies on having a three-pin lead with earth pin. Non-ESD-safe stations and irons usually have a two-pin plug. The invisible difference is that the T2040 is a 68W station, while the T2460A is a 100W station. So, we devised a simple, barely scientific test to compare them.

We cut eight 6cm sections of 0.7mm rosin-cored 60/40 Tin/Lead solder from the same roll, and bent them over a 3mm drill bit so that they were U-shaped with sides the same length.

Then, both soldering pencils were set up on helping hands so that the pencil was level. One piece of solder was placed on each tip, and in turn, each iron was turned on with the temperature set for 275°C. On the T2040, the lock feature was used for this, and the power switch controlled everything. On the T2460A, power on results in a default temperature of 150°C. Pressing the white button increments through the preset temperatures, so this button was pressed immediately after power on, when the iron was well below 60°C and therefore, this did not affect the warmup time.

Each iron was timed from power on, to when the solder melted through and dropped off. Each iron went through this process four times, returning to air conditioned room temperature of 25°C (measured) with power off between tests. Additionally, the tip was cleaned with brass wool before being allowed to cool down. The time taken was averaged across the four tests. The only significant difference between tests was that the T2040 had its supplied 1.2mm chisel tip fitted, while the T2460A had a 0.8mm conical tip.

There was one thing we forgot about, however: There is a thin layer of oxidation on the outside of solder, and it is not great at heat transfer. Additionally, when two circular sectioned surfaces are touching, the point of contact is tiny. We gained wildly varying results, and it was observed that the solder sometimes sat on the tip of the iron without any sign of melting, then melted instantly when bumped. The weight of the solder was just not enough to overcome this.

So, we repeated the test, but with the end of a length of solder applied to the tip with a bit of pressure from a second helping hand. The end of the solder was cut with a knife each time, to ensure the same surface area. This time, we gained usable results. From power-on, to when solder first melted, the T2040 took an average of 18.875 seconds, while the T2460A took 16.4 seconds. That is not much of a difference, and in practice it would not be noticeable. It may be an indication of heat capacity, or it may not. A further test was needed.

The other test we decided to perform, again not very scientific, was to explore the tip temperature recovery. To do so, we randomly populate a piece of strip board with surplus and old components, to a density as high as practical. Then, we soldered as many as we could in one go. If tip temperature recovery was poor, then the station would struggle in this test. Just to make absolutely sure, we tested it with Altronics' Lead Free 0.8mm solder, a mix of 99.3% tin and 0.7% copper, for half the connections, and our regular stock of 60/40 tin/lead solder for the other half. Of those, half were done with the 68W T2040, and half with the 100W T2460A.

With the 0.8mm lead-free solder, the T2040 required a temperature of 360­°C for good flow and wetting when joins were performed at speed. We needed 325°C just to get a quality connection, even when working at a snail's pace. By comparison, the T2460A (keeping in mind that this is a 100W iron with a normal price three times that of the T2040) needed 325°C to produce a quality joint, but was able to do so at speed without increasing temperature. When 60/40 solder was used, the T2040 was able to produce quality joins as fast as we could work, at 275°C, even when filling a whole empty track with solder as is done for current capacity and heatsinking sometimes. The difference between the two is definitely more apparent when working with that particular lead-free solder.

CONCLUSION

All in all, the T2040 is an impressive and well-built soldering station within its price bracket. It has a healthy range of available tips at reasonable prices, and is unlikely to break apart any time soon. If your workbench is compact, then this compact soldering station may be the perfect choice. If your workbench is the size of a banquet table, then this soldering station may still be for you. It only started to struggle when trying to solder lead-free at the lowest temperature practical, and we only tested that one particular lead-free solder. It could be that a different alloy would perform better still. So, unless you need production speed with lead-free solder, you won’t find many things to say against this iron.

LEAD, LEAD-FREE SOLDER, & PROBLEMS WITH BOTH

The subject of lead-free soldering, and why an iron designed for it is needed, is still a mystery to many. Plenty of makers still use 60/40 solder, (60% tin (Sn), 40% lead (Pb)), and in Australia, there is no ban on it. Lead-free solder has many detractors, but so did alternatives to DDT when it was first put in the spotlight. There are valid points on both sides of the argument.

Lead has many documented environmental issues after disposal, regardless of how far some people push their head into the sand and deny it; on top of that, recent research from the last fifteen years or so has indicated that the maximum safe level of lead exposure (that which the human body can absorb or process without permanent damage) is much lower than traditionally accepted, and some research even suggests there may be no safe exposure level. The challenge with solder is that, while solder itself is stable and relatively inert, environmental exposure and chemical action both cause liberation of the lead from the alloy in disposal situations.

Adding lead to tin forms an alloy with properties different from either metal on its own. Alloys with high amounts of tin, or even solders purely made of tin, are more brittle; susceptible to corrosion; form powdery surfaces; do not flow as well; do not 'wet' as well (the property of a liquid 'sticking' to a surface); and have a higher melting temperature. However, while original lead-free solders were poor, material science is progressing. There are now a range of lead-free solders available, containing different metal combinations. These are all eutectic alloys, meaning that the combination has a lower melting point than any of the component metals in their pure form, and behave as one mass rather than two different parts melting at different temperatures. Not all of the pitfalls are gone, however.

Even so, the need to remove lead remains, and the industry has adapted. Original lead-free solders needed significantly higher temperatures than lead-containing solder, and tin is corrosive to many other metals. This meant soldering irons designed for early lead-free solders had high maximum temperatures, and thicker iron coatings on the tips, among other changes. However, things have improved, and most current lead-free solders melt only at 20°C or so hotter than traditional solders. Instead of getting much hotter, a lead-free iron now focuses on heat capacity and fast temperature recovery.

The rating in Watts of a soldering iron is the power of its heating element, but this alone does not relate directly to the speed of heating: If the heating element, tip, and related components are not designed well, heat transfer is still slow. The most important focus of a lead-free soldering iron is that the tip can pass heat quickly and continuously, with fast recovery, into the solder and join, so that the more stubborn solder melts before the join becomes overheated. In addition, tips are designed with different iron alloys coating them, for better resistance to the ability of molten tin to dissolve some metals.

With the right iron and the right alloy, good soldering with years of reliable joint quality is easily possible with lead-free solder. Some modern blends don't even look visually different from lead-tin solder, unless you're a metallurgist. It does come down to careful choices, however, and likely a degree of trial and error to find one that suits you.

The 68W Lead Free Soldering Station is available from Altronics: www.altronics.com.au

T2040 $125