Hot Air Rework Station: Essential Guide

Hot air stations, also known as hot air soldering stations or hot air rework stations, are widely used in high-precision electronics.
They are ideal for desoldering and attaching components to complex circuits where using a soldering iron would be impractical or impossible.

This article will give you all you need to know about these wonderful tools.

What is a Hot Air Station?

Hot air stations have a similar shape and, like soldering stations, are designed to melt solder. However, the similarities end there; hot air stations are contactless, have a different working principle, and can do some jobs that can’t be done with a soldering iron and vice-versa.

Hot air stations melt solder through a stream of hot air that flows through the tool’s tip. This system allows heat to reach complicated areas where a conventional soldering iron wouldn’t, and thanks to their precise temperature and airflow regulation, they are ideal tools for attaching tiny components to intricate circuits.

Hot Air Station vs. Reworking Station

Although people often use both terms interchangeably, some hot air stations are called reworking stations, because they enable desoldering components with high precision and without damaging the PCB (Printed Circuit Board). This is great for repairing jobs, fixing soldering mistakes, and mounting SMD, MLP, and other delicate components.

Some reworking stations also bring an additional control panel and a soldering iron, saving space and time.

How Does It Work?

Hot air stations work like small hot air guns; they have a fan that sucks air, making it go through a resistor that heats the air to the desired temperature and releases it through a nozzle at the tool’s tip. This enables the hot air to focus on a much smaller area compared to a heat gun or blow dryer.

Some models have the fan and heating element inside the handle, while others have these components inside the main or control unit.

Models featuring the heating element and fan in the main unit are usually more expensive. These models are quieter, offer more accurate temperature control, and their handle is thinner and lighter, making them more comfortable for extended working sessions.

The main unit houses the power transformer and the control panel, where you can adjust the air temperature, fan speed, and a temperature display. As mentioned earlier, some models also incorporate the heating element and fan.

2-in-1 Rework and Solder Station

These are devices that combines soldering station and hot air rework station.

2-in-one devices bring a reworking station with its respective temperature control and settings and a second port where a soldering iron is plugged.
The 2-in-1 devices are more practical than buying a soldering iron in addition to a reworking station.

Temperature Range

Depending on the model and power, hot air stations have air temperature ranges of 100°C to 550°C (212 to 1076 °F). This covers the soldering temperature for most common uses.

Unlike their cousins, the soldering irons, hot air stations’ power, or wattage doesn’t impact so much on the maximum heat they can generate but on their heat-up time, or in other words, how fast they take to reach or recover the desired temperature.

Like any tool that generates high heat, safety is of paramount importance when using a hot air station. For a comprehensive guide on soldering safety, please refer to our article here.

The airspeed, measured in liters per minute (L/min), goes from 100 to 180 L/min. Some models have a “cold air” function that enables switching the heater off by holding a button on the handle, and others also have a switch to turn the fan “ON” and “OFF” for a more practical and faster operation.

Airflow Types

Depending on their construction and fan, hot air stations can deliver air in two ways:

1. Vertical Wind: This type of airflow goes straight from the nozzle into the soldering area, which is useful when you need to concentrate the heat on a specific part or component, providing a focused stream of hot air. It’s suitable for soldering or desoldering small components or removing individual solder joints.
   The downside of vertical wind is that it tends to concentrate heat in one spot when applied to large areas, which may be dangerous to the circuit and the components.
2. Helical Wind Type: This airflow type provides a more even heat distribution; the air travels in a circular, spiral pattern before hitting the soldering area. This results in a more evenly distributed heat, ideal for working on large surfaces without risks of damaging the components or circuits, and it’s practical for desoldering multiple components at once.
   This wind type achieves a uniform temperature across the soldering area than the vertical wind.

Before choosing a hot air station, it’s essential to consider its airflow type and the type of job you will be doing the most.

Usually, when the kind of airflow is not mentioned in the device specs, it’s often an indicator that it delivers a vertical airflow. Cheap models are generally of this type, and more expensive models use a helical wind type, as described on its features list.

However, most semi-professional devices like the SUGON 8620DX allow you to choose the airflow type.

Main Uses of Hot Air Stations

Hot air stations are very practical for speeding up simple soldering tasks and crucial for many complex electronic jobs. In the following list, you will find a list of their most common uses.

1. Desoldering Electronic Components

Hot air is excellent for removing components from PCBs safely and quickly.

Some components, like microchips, can have more than 20 pins, and these tools allow you to desolder them all at once without damaging the board or nearby components. Tasks like this could take much more time using a contact soldering iron and would be dangerous for the circuit.

2. PCB Rework and Repairing Complex Devices

Hot air stations are ideal for repairing complex, intricate circuits like motherboards and cellphones. They allow you to desolder damaged components and replace them quickly.

Sometimes you will need a conventional soldering iron, and that’s where 2-in-one stations are so practical.

3. SMT Jobs

SMT (Surface Mount Technology) requires working with SMD and SMC components (Surface Mount Devices and Surface Mount Components). This technology is the most used in today’s industry and is commonly found on advanced devices like cell phones, vehicle electronic modules, computer motherboards, and other gadgets.

SMT boards don’t have holes, and the components are soldered on the top of the board. With patience, you can solder some of these components to the board using a soldering iron.

Still, some components, such as MLPs (Micro Leap Frame Package) and BGAs (Ball Grid Arrays), have their pins underneath, not on the sides, making them impossible to reach using a soldering iron. Hot air soldering stations allow soldering them easily as they can heat solder paste underneath.

4. Soldering Fine-Pitch Components

These components have their pins so close that using a soldering iron to attach them to the board without creating a bridge is impossible. Hot air stations allow you to solder them without a problem.

Nozzle Types

Nozzles on soldering stations’ hot air guns are exchangeable. Choosing the right one for the job is crucial to achieving the best possible results, ensuring a great soldering experience.

Below you will find a list of the most common nozzles and their uses:

1. Round Nozzle: These nozzles are the ones that usually come from the factory. They have a circular opening that provides even heat distribution and is versatile for most tasks. These nozzles come in different diameters, depending on the component’s size and surface.
2. Conical Nozzle: These are tapered and concentrate the hot air flow into a focused area. They prevent heating nearby components and are ideal for precision soldering and desoldering tasks where concentrated heat is critical.
3. Flat Nozzle: These nozzles have rectangular or squared openings. They are designed to distribute heat evenly over large surfaces, making them ideal for soldering or desoldering large components, especially those with multiple leads. This nozzle has broad coverage, ensuring consistent heat distribution.
4. Reflector Nozzle: These nozzles have a conical shape with an extended tip and a reflective interior. Hot air is reflected into the component from multiple angles. This nozzle type is usually practical to achieve a uniform reflow of solder paste while soldering.
5. Curved Nozzle: These nozzles come in different sizes. They are practical when applying hot air to components located at difficult angles.
6. Fine-Pitch Nozzle: These nozzles usually have 3mm and are designed for soldering and desoldering fine-pitch components and connectors.

Essential Accessories for Hot Air Stations

When using a hot air station, you can’t just place the components by hand. Besides, you will need some products for cleaning, preparing, and making the job easier.

• Solder Paste: Solder paste is perfect for working with surface-mount PCBs and components. You just have to apply some paste over the board’s soldering pads and hold the component with tweezers. The hot air will melt the paste, creating a solid bond between the part and the circuit.
• Flux: Applying flux over the soldering pads is great for cleaning the surface and reducing the solder’s surface tension, which can lead to a component misplacing. Besides, flux prevents solder bridges and helps solder to melt quicker, protecting both the component and the board.
• Isopropanol: This alcohol is excellent for cleaning and preparing the surface before soldering, mainly when fixing a circuit or replacing a component.
• Cotton Swabs: They are practical for cleaning the contacts and circuit pads before applying the soldering paste.
• Tweezers: A set of tweezers or pliers in different sizes and shapes is ideal for holding components in place when soldering or for removing them from the board after desoldering.
• Stencil: There are stencils with the shapes of the most common pin layouts, ideal for building new circuits or replacing components. These stencils allow you to apply solder paste with precision, and it’s helpful when soldering tiny components or with many connections where applying the paste accurately can be difficult.
• Fume Extractor: Using a hot air station produces poisonous gases. Even when working in a properly ventilated area, a portable fume extractor is a great way to protect yourself from the fumes caused by the soldering process, mostly when soldering for long periods.

Is a Hot Air Station Worth Buying?

As you get involved in electronics deeper and deeper, you will find yourself with jobs requiring working with SMD components and circuitry. Even when you do it like a hobby, you will eventually want to improve your boards, or you won’t find through-hole components available for a project, and you will be limited if you don’t have a hot air station at hand.

Hot air stations’ prices go from less than $100 to over $1,000, depending on their quality, features, and brand. You can get decent 2-in-one reworking stations for about $120 and semi-pro hot air stations for about $250.

Before buying, read the specs well, and if you plan to work a lot with SMD circuits, think big, and try to buy the best tool you can, as it will help to steep up your learning curve and save you a lot of money by reducing the chances of burning or damaging expensive components.