Selecting the right soldering/de-soldering (S/D) station is very important for any project when it comes to printed circuit boards (PCBs) and semiconductors. Occasionally, we end up buying a cheap, unreliable S/D station that either causes damage to components or stops working after the first or second use. The hazards of selecting an incorrect S/D station were discussed in the buyers’ guide on rework stations published in January 2014 issue of Electronics For You.
It is advisable to know the required parameters before selecting an S/D station. But to know the parameters, it is essential that we know the basic requirement of the project in hand. From electrical to design parameters of the S/D, all should comply with the project to enable an efficient and safe working environment.
The next thing you should know is the new styles of S/D stations available. There could be S/D station styles with many old features incorporated along with the new ones. Information about the new styles of S/D will not only increase your options but also help you identify features you should look for.
You must be aware of the common features that are considered as selection parameters for an S/D station, such as a replaceable iron tip, temperature control setting, pre-set temperature option, lightweight iron rod and output voltage of the iron. Apart from these, there are other important parameters that we generally miss out. These are electrostatic discharge (ESD)-safe design, thermal recovery, temperature accuracy and tip-to-ground ratings.
ESD-safe designs. All S/D stations work on electricity that gets converted into heat, creating an electric field around these. This may lead to electrostatic discharge at times, further creating device failures during S/D. The devices that we work on now-a-days are pretty compact and delicate to escape the damage caused. Thus, it is essential to look for an ESD-safe soldering station that prevents static from building up by grounding the iron.
Thermal recovery. The thermal recovery of an S/D is directly proportional to its power. An S/D station with low power will lose heat fast and will have a lower thermal recovery. Thus, an S/D station with low power will be slower to work with. Since thermal recovery of any S/D station is not usually mentioned on it, you should look for its power ratings. An S/D with a power rating of 50W to 80W is considered to be the best for fast operation, whereas an S/D station with power rating of 20W to 30W, or even lower, is unsuitable for most projects.
Temperature accuracy. It is natural to be curious about what this term is and why it is important. To clarify this term, let me take an example.
We set our S/D stations to a specific temperature for efficient work. However, do we ever bother to know if the tip of the iron has reached that temperature, or how close is it to the set temperature? The temperature accuracy gives us that idea. Ideally, the accuracy should be ±0.001°, which is impossible, but an S/D with ±5° of temperature accuracy is considered suitable.
An S/D station with adjustable irons and tips should have the accuracy calibration option to maintain the working efficiency of the S/D station.
Tip-to-ground ratings. This rating refers to two different parameters: potential and resistance. Tip-to-ground potential is the existing voltage between the tip of the S/D iron and the common ground of the station, and the tip-to-ground resistance is the resistance between the two.
The first is the leakage potential, which should not be more than 2mV, while the resistance should not be more than 5Ω. Otherwise, the overall current will leak out and the station will never provide the required efficiency at work.
New features to look for
You can never make the best choice if you do not have information on what is new in the market. Although you will find a few new styles of S/D stations with respect to their looks and design, the ones listed below are some of the new features.
Ultra-fast thermal recovery. You might have got a synopsis of thermal recovery in the previous few paragraphs, but ultra-fast thermal recovery is something even beyond that. Only a soldering station with high wattage like 120W or 150W can provide this type of recovery, allowing you to operate it at a very low temperature set point. This minimises your concern about the influence of heat on the components and the tip of the iron.
Such soldering stations have an auto-sleep function along with a power shut-off that gets activated once the set temperature is reached, preventing the soldering iron from getting over-heated and thus increasing life of the station and the tools attached. The auto-sleep also prevents oxidisation of the tip of the iron.
These soldering stations are used for fine SMD soldering, high mass soldering purposes and soldering parts of a heavy automotive.
Temperature pre-set. All the new S/D stations that have come up recently have the temperature pre-set option, where three frequently used temperatures can be set in advance and then the required temperature can be recalled with just a single push of a button. This is an added advantage to the temperature control function that we usually look for in any S/D station.
Ultra-light soldering iron. A light soldering iron is advisable for comfort at work. Today, you can get a soldering station with an ultra-light-weight soldering iron that weighs not more than 95 grams. The plug-in type soldering tips with different shapes and sizes further add to this feature by providing the optimum working facility for compact boards with more than hundreds of components to be soldered in.
User-friendly. You can also see simple and user-friendly S/D stations that not only provide different factory settings for adjustment of variable temperature, calibration value and standby time, but also provide the ability to use fixed temperatures, interlock and energy levels with the use of PC software or a micro SD card. Another special feature in such type of S/D stations is the shut-down and standby function that helps save energy, increasing the life of the iron tip at the same time.
Thermal control and lock. Have you ever thought of controlling the heat of the S/D station and locking it at a certain point so that the iron does not get overheated, eventually damaging the project? Think now, if you haven’t before.
The new S/D stations available now come with a control card that turn off power to the station if the iron tip reaches the set temperature. Now, to check if the tip of the iron has reached the set point or not, they have temperature sensors incorporated at the tip.
Such S/D stations provide certain features that are required for industrial manufacturing. These features are: compact design for energy saving, information regarding the errors and offset functions to moderate the heat. Such S/D stations are considered suitable for a wide range of applications starting from few touch-ups to heavy-duty work.
Temperature sensors and alarm. This is a soldering station that allows no fluctuation in temperature during continuous operation at heavy load. To support this feature, such stations have high-sensitivity sensors connected to an alarm that turns on when the temperature of the tip goes above or below the maximum and the minimum temperature settings. The alarm again turns on if the iron is left in contact with the component or the board longer than the time set. This also prevents overheating of the components.
Another option which this soldering station provides is that, it is designed with thermal insulation capability to reduce the transfer of heat to the grip of the iron, allowing one to hold the iron for a longer time.
Based on Curie heat technology. In this type of heating technology, as soon as the power to the soldering station is turned on, the AC signal goes to the handle through a coil, due to which an eddy current is induced in the heater (that is ferromagnetic) to increase its temperature. Now, as soon as the temperature reaches the Curie point, the magnetic properties of the heater change, inducing no further eddy current and turning off the heat. But as soon as the temperature goes below the Curie point, the current is induced again, generating another heating cycle.
Such soldering stations are dependent on the type of heating material used. Today, soldering stations available with this heating facility provide an excellent energy conservation option. Such stations avoid any temperature overshoot even during the temperature recovery of the tip.
Hybrid S/D stations. S/D stations are said to be hybrid when these use hybrid tools in conjunction with hybrid heating technology that combines infra-red (IR) radiation with conventional heating, especially for SMD components. The IR radiation allows the tools to transfer heat to the components homogeneously.
Such stations have exchangeable hybrid adaptors that protect the chips from getting damaged during the heat transfer. These generally have high-power heaters, with wattage of about 200W.
The choices are many with respect to features, but yes we do have some parameters now to guide us. Don’t you think the new styles will affect the selection parameters in the days to come?
The author is a technical journalist at EFY