With large number of Hardware Startups, Makerspaces & Atal Tinkering Labs being setup across the country, the demand for soldering stations witnessed a massive growth. To keep the buying hassles at bay you need a proper step by step guide which not only discusses the basics but also points out the latest that is available in the market. Here is such a guide.
Why you need such a guide?
Electronic Projects have their own requirements when it comes to soldering. While you can get your work done by a cheap unregulated 230V 25 Watt iron that plugs directly into the mains & heats up to uncontrolled high temperatures, only in some scenarios, you would be unable to produce desired results in most cases. Cheap soldering irons or even stations won’t last long & you will regret buying such a cheap iron if you are into serious professional work involved in startups, makerspaces or business establishments like R&D Labs. After knowing your project requirements you can use this guide to find the most appropriate soldering stations for your work area.
What is soldering?
Soldering is an art by which electronic components are connected with each other so that they can communicate in a circuit & perform a specific task. Electronic components are held by a board called PCB (Printed Circuit Board). The leads of Electronic components are joined to the PCB by melting Solder wire & then waiting for it to cool & solidify. PCBs then either have external copper wires (in General PCBs/ Perfboards) or printed copper tracks (Advanced FR4 Grade PCBs) that help in establishing the required connections.
Some basics about soldering stations
Prior to selecting the right soldering station as per your need, you should first know about the basic terms associated with soldering. These are described below:
It is an alloy made by combining two or more elements. The type of elements used decides the melting point of the solder alloy. These are supplied in various forms such as wires, bars & balls as per requirement. One thing to note is that almost all forms of solder alloys now-a-days comes with electronic grade flux inside them. Different type of solder alloys are:
(a)60Sn-40Pb (This is the most popular & widely used solder alloy which melts over a range of temperature from 183OC to 190OC. This is a lead based solder alloy which is prohibited in European Union countries. However, this is the one which is most easily recognizable in case of good solder joints due to its shiny appearance.)
(b)63Sn-37Pb (This is used where more professional results are required. Rather than melting over a range of temperatures, this type melts at a specific temperature of 183OC and solidifies at specific temperature too.)
(c)99.3Sn-0.7Cu (This is a lead-free solder alloy composition that melts at a high temperature of about 227 OC but is allowed in EU Countries. This type of solder alloy is very difficult to work with as the good solder joints formed using this type are not shiny.)
It is available in various types such as liquid, paste, gel or even in form of flux pens. Flux pens are indispensable if you are into soldering of SMD (Surface Mount Device) components. In case of through-hole components no additional flux is required as the flux contained in the solder wire is enough for the purpose. The action of flux is simple – it is corrosive at soldering temperature & thus cleans the surfaces to be soldered while being non-corrosive at room temperatures.
It is a short term for Surface Mount Device components – the technology towards which the world is gearing up now-a-days. These components are extremely small compared to their big counterparts, i.e. through-hole components.
4.Power plane: The copper area on a PCB through which transmission of high voltage & current takes place is termed as power plane. Generally pads in these areas suck a lot of heat from the tip of soldering iron.
The solder joint which is formed as a result of improper heating is called dry solder joint. The electronic product with a dry joint may function perfectly initially but start giving problems very soon. These joints are highly unreliable & very difficult to trace during troubleshooting.
6.Copper Pads with/without thermal relief:
If there is no thermal relief provided to a copper pad (that is on a power plane) then that joint will absorb & dissipate more heat from the soldering iron tip. If the soldering iron lack to fulfill the required thermal demand the joint will start cooling down & there would be formation of a dry joint.
7. Working of a soldering station:
The working of a soldering station is pretty straightforward. The control card (a kind of electronic circuit with on-board MCU, microcontroller) governs the power delivery to the heater to change its temperature accordingly with the feedback from both UI (User Interface) & the sensor. The User Interface of soldering stations generally consists of knob(s)/button(s). The UI also consists of a LCD/LED display to show the set & run temperatures of the soldering tip.
Soldering Station: Specifications and features
Now equipped with all the basic information, the second thing you should know to make a good purchase decision is the specifications & features of the soldering station. These are discussed below one by one:
All soldering stations irrespective of being analogue or digital have a base unit to which a soldering iron/pen/pencil is attached. The base unit consist of the control circuit card & UI. The digital station shows both the set & running temperatures on its LCD/LED display while the analogue does away with only a LED bulb & a variable knob. The digital version is more of a professional kind but expensive too.
The wattage of soldering stations is an important parameter to consider. The wattage rating totally depends on the size of the components & PCB type. The absorption & dissipation of heat is more in case of large components, heatsinks & pads on power planes. If the soldering station can’t deliver the amount of power required, the joint would start cooling down & it will result in a dry joint. If your project involves ICs & small components then a 50 Watt soldering station is adequate for the job. However, if there are parts like large heatsinks, 10 guage copper wires etc. consider buying a 100 Watt soldering station.
3. Input voltage:
The input voltage of soldering stations is an important specification that should be taken care of otherwise you end up buying a station incompatible with the power from the wall socket. Some units come with an input voltage of 120V AC which is incompatible in the countries with 230V AC at wall socket.
It refers to how close the temperature at the tip is to the temperature set by you at the station. Sometimes temperature accuracy is compromised by the designers for the sake of cost-effectiveness. Tolerance of the components is another factor that affects the temperature accuracy. Laws of thermodynamics can be used to determine that how the shape & size of the tip affects the temperature accuracy. Thick tips retain heat in a better way compared to thin ones. Generally, the temperature accuracy of an ideal station should remain within +/-5OC.
This specification tells us that how well actually the control card circuit is working, allowing for the heat losses into the atmosphere by the tip yet keeping the tip temperature as close as possible to the set temperature. Such specification is valid only when the iron is kept in stand & is not used for soldering purpose. A value of +/-1OC is acceptable.
The term itself state its meaning. When an operator moves his soldering iron from a finished joint to a new joint (to be soldered), there is temperature drop in the tip of the iron due to heat losses at the finished joint. Thermal recovery is the measure of how quickly the iron tip returns (recovers) to the set temperature. This specification is not present in the documentation of the soldering station & to get an overall idea of thermal recovery one should look into the power rating of the soldering station. More the power rating (in watts) of the soldering station faster it will recover thermally.
7. Tip-to-ground potential:
It is also known as millivolt leakage. Actually it is the voltage that exists between the tip of the soldering iron & common ground point of the soldering station. The ideal value should be below 2mV. If this value exceeds 2mV criteria then the soldering iron can cause serious damage to the project due to leakage current.
8. Tip-to-ground resistance:
It is the resistance present between the tip of the soldering iron & common ground point of soldering stations. The ideal value should be anywhere between 2 Ohms to 5 Ohms. If the station exceeds these values then there could result a possible damage to the project due to leakage current.
9.Variable Temperature Range:
Different soldering joints have different tip temperature requirement as well as different types of solder melt at different temperatures. So it would be a wise decision to evaluate the temperature requirements of the job prior to making the purchase decision.
10. ESD Safe Design:
Modern SMD components are quite delicate & compact to bear the damage caused by the static charge. The damage could be caused during soldering operation too, if the soldering station is not ESD Safe (Electrostatic Discharge safe). The soldering stations that are marked ESD Safe use static dissipative material in their construction so that static charge doesn’t build up on the station itself. Also tips of such irons are well grounded.
Along with ESD Safe soldering stations one should not avoid other antistatic accessories like wrist strap, ankle strap, mat, storage, cleaning brushes etc.
Various types of tips/bits of Soldering Stations
We should now have a look at the various types of tips/bits available in the market
1. Chisel bits/tips:
This type is the most widely used soldering tip & also the most popular one also. It has a tapered edge at one end making it easy to fit with most components whether be SMD type or through-hole type. Due to its large surface area it heats the components in the best possible way. Some of the popular sizes are 1.2D, 1.6D, 2.4D & 3.2D.
2. Conical bits/tips:
However these tips come standard with most soldering stations, these are no good when it comes to soldering due to their lacking surface areas. These tips must be used only in hard to reach areas of a project.
3. Bevel or spade bits/tips:
This type is also a widely used one. It is more of a combination of chisel & conical tips giving an added advantage. Some of the popular sizes are 2C, 3C & 4C. These are very useful for soldering SMD QFPs (Quad Flat Packages) & SOICs (Single Outline Integrated Circuits).
4. Blade or knife bits/tips:
These are used in pad leveling & SMD soldering applications.
Classification of various Soldering Station models available on the basis of power (in watts)
Armed with all the basic knowledge about soldering & specification criteria, it’s time we move on to our main section of various soldering stations available based on their power ratings.
50 Watt stations
Duratool offers a 48 Watts soldering station Duratool D00678 at an unbeatable price tag of Rs 5250/- (element14 India). Its tip temperature is variable from 150OC to 450OC. Soldering stand & sponge are built-in and it operates at 230V/50Hz AC. It has a LCD display which shows set & run temperatures. Its iron operates at 24V. Its shell size (WXHXD) is: 195X87X155mm without electric iron. It weighs 2000g. It is ESD Safe by design.
Another offering from Duratool is also a 48 Watts Station Duratool D02265 which costs Rs 1485/- (element14 India). Its tip temperature is variable from 150OC to 480OC. Soldering sponge & stand are in-built into the system. It operates at 220-240V/50Hz AC. It comes with a mica heater & a knob to vary the temperature of the tip.
Our third contender in 50 Watt category is Weller WESD51D which is high on features. It is a 50 Watt soldering station and costs Rs 18698.27 (element14 India). Its tip temperature is variable from 180OC to 450OC. Soldering sponge and stand comes as a separate unit. It operates at 240V AC. The iron operates at 24V. Temperature accuracy is +/-6OC. It is a MCU Controlled unit & features LED Display. It provides a knob to vary & set the required temperature. Display can show temperatures in both OC & OF scales. It is an ESD Safe station.
60 to 70 Watt Stations
The first soldering station we look at in this category is Hakko FX888D model by Hakko Corporation. It is a 70 Watt station and costs Rs 12950/- (Tanotis India). Its tip temperature is variable from 50OC to 480OC. Soldering sponge (both cellulose & brass type) & stand comes as a separate unit. This site sells a model that operates at 120V AC. So you need a 240 to 120V AC converter if your wall socket outputs 230V AC. The iron operates at 26V. Display can show temperatures in both OC & OF scales. Temperature stability is +/-1OC at idle temperature. Dimensions (WXHXD) are: 100X120X120mm. It features a LED Display for set & run temperature readouts. The station also provide preset temperature input with the help of which previously stored temperature can be recalled with a click of a button. It is ESD Safe. Tip-to-ground resistance is 2 Ohm while tip-to-ground potential is 2mV.
The second soldering station in this category is Metcal PS900. This station works on advanced smartheat technology. What this means is that the power delivered to the tip is automatically varied as per the thermal demand of the thermal load keeping the temperature of the tip constant. This station achieves this using a special heating element that works on Curie point heating technology. Its basic power consumption is 60 Watts. Soldering sponge (both cellulose & brass type) & stand comes as a separate unit. It is priced at Rs 15211/- (element14 India). Its input voltage ranges from 100-240V AC. Its input line frequency is 50/60Hz. Its dimensions (WXDXH) are: 80X160X115mm. Tip-to-ground potential & resistance are less than 2mV & 2 Ohm respectively. Its temperature stability is +/-1.1OC. Its iron cord is burn-proof & the station is ESD Safe by design. This system doesn’t need calibration.
The third soldering station we are looking at is Soldron 938 digital temperature-controlled soldering station. It is priced at Rs 3900/-(Soldron Soldermall India). This station comprises of microcontroller based smart circuit design which goes to sleep automatically if not used for a specific period of time thereby saving energy & preventing the oxidation of tip/bit. It is a 60 Watt station and its tip temperature is variable from 200OC to 450OC. Its input voltage is 230V/50Hz AC. The display shows both set & run temperatures & a knob is provided for temperature adjustment. It is ESD Safe by design. Soldering sponge & stand comes as a separate unit which you can move as per your convenience in your work area. The iron operates at 24V.
90 to 100 Watts Stations
The first contender in this category is Pace ST 50 soldering station. It costs Rs 47101 (element14 India). It is a 90 Watt soldering station. The station’s power supply allows multiple heating technologies to be governed by a single type of power supply. This means you don’t need multiple power supplies anymore & can effectively use your workbench space. Pace calls it Intelliheat Technology. The stations temperature range is variable from 37OC to 482OC (with a SensaTemp Digital Control). SensaTemp is a type of technology used by a soldering iron. Unlike other soldering stations which use thermocouple sensors, the SensaTemp uses more accurate platinum sensor. Its input voltage ranges from 197-253V AC with frequency of 50/60 Hz. It has a LED Display for displaying the temperatures. It is ESD Safe by design. Its temperature stability rating is +/-1.1OC at idle tip temperature. Its tip-to-ground resistance is less than 2 Ohms. Its dimensions (HXWXD) are 104X130X152mm.
The second soldering station we are considering is Soldron IST 100. It is priced at Rs 8000/- (Soldron Soldermall India). It is a 100 Watt soldering station. The tip temperature is variable from 200OC to 480OC. This station is compatible with lead-free solder. The input voltage of this station is 230V/50Hz AC. The iron operates at 36V. This iron is most suitable for high mass soldering as well as soldering of sensitive SMD Components. It has got a digital display for showing set & run temperatures. It has auto sleep functionality which conserve the bit. It heats up to the set temperature within 15 seconds. Its temperature stability is +/-1OC. It is a microcontroller controlled unit & works on advanced induction heating based technology. It is ESD Safe by design.
The last soldering station we are considering in the 100 Watts category is Weller WT1010. It is priced at Rs 44161.72 (element14 India). It is a 95 Watt soldering station. Its tip temperature can be varied from 100OC to 550OC which is tool dependent. Its input operating voltage is 230V, 50/60Hz. Its temperature stability is +/-2OC. Its dimensions (WXDXH) are 149X138X101mm. It weighs 1.9 Kg. It comes with a backlit LCD display. It is ESD Safe by design.
All prices are indicative only. Kindly check websites before making purchase.
Some Do’s & Don’ts
1. Never tap the solder tip on hard surfaces or rub it using hand file.
2. Frequently tin the tip of the soldering iron. Leave a blob of solder on the tip when you finish soldering.
3. Don’t over-wet the cleaning sponge and avoid excess thermal shock to the tip of the iron.
4. While selecting a particular model of a soldering station it should be enquired that whether its spares like cleaning sponge, brass sponge, tips/bits, heaters are readily available and appropriately priced or not.
5. Each process of soldering should be validated & it should be noted that at what temperature better to best soldering takes place.
6. Never set the soldering station to its maximum temperature for longer periods of time.
7. The quality of after sales support is one area you should pay thorough attention.
8. Proper ground connection & proper layout of power cables is a must-have in any lab.
The Final Word
Now that we have seen a comparison of some of the very interesting soldering stations available, it’s time to go for shopping & pick one up which suits your needs most appropriately. Happy Soldering!
To Read about various Soldering Irons: click here