The Ultimate Guide To Using Solder Investment

Soldering is a fundamental skill for anyone working with electronics. It involves using a filler material (solder) to join pieces of metal together. The process is simple: heat the solder and use it to coat the pieces you want to join, then let it cool. As it cools, the solder hardens, creating a strong electrical bond between the parts.

To get started with soldering, you'll need a few basic tools and materials. A soldering iron is essential, and you'll also want a soldering stand to hold it when it's not in use, as well as a sponge to clean the tip of the iron. Solder comes in different thicknesses, so make sure to choose the right type for your project. You'll also need something to hold the items you're soldering, like a helping hand device with alligator clips.

Soldering irons

A soldering iron stand is also very useful to have. This stand helps prevent the hot iron tip from coming into contact with flammable materials or causing accidental injury to your hand. Most soldering stations come with this built-in, along with a sponge or brass sponge for cleaning the tip.

When choosing a soldering iron, it is important to consider the type of work you will be doing. If you are working on delicate electronics components, you will need a soldering iron with a fine tip that can deliver heat to smaller areas without affecting its surroundings. On the other hand, if you are soldering wires or other larger components, a soldering iron with a broader, flatter tip would be more suitable.

It is also important to note that soldering irons can reach extremely high temperatures, so caution should always be exercised when using this tool. It is recommended to use a soldering iron stand to help prevent accidental burns or damage. Additionally, it is important to solder in a well-ventilated area, as the fumes released during the process can be harmful to your eyes and lungs.

Before you start soldering, it is crucial to prep your soldering iron by tinning the tip with solder. This process will improve heat transfer and protect the tip, ultimately extending its life. To do this, simply attach the tip to the iron, turn on the soldering iron, and let it heat up. Then, wipe the tip on a damp sponge to clean it and apply solder to the tip, ensuring it flows evenly.

When soldering, it is important to bring both the metal surfaces and the solder to a high enough temperature for the solder to melt and create a strong bond. The specific temperature will depend on the type of solder you are using.

In summary, soldering irons are an essential tool for anyone looking to solder, and by following the proper techniques and safety precautions, you can successfully create strong and reliable connections.

Soldering stations

A soldering station is a more advanced version of the basic standalone soldering pen. If you are going to be doing a lot of soldering, these are great to have as they offer more flexibility and control. The main benefit of a soldering station is the ability to precisely adjust the temperature of the soldering iron, which is great for a range of projects. These stations can also create a safer workspace, as some include advanced temperature sensors, alert settings, and even password protection for safety.

• Soldering iron or soldering gun (often comes with multiple nozzles)
• Hot air gun or wand for reworking PCB board components
• Desoldering iron or solder sucker for melting and removing solder
• Smoke absorber to protect users from toxic soldering fumes
• Vacuum pick-up wand to conveniently pick up small components
• Temperature control to adjust and select the desired temperature
• LCD or LED digital display for temperature readout
• Programmable settings so you can save preferred temperature and other settings
• Automatic shut-off that detects a lack of movement and will turn off your soldering iron
• Tip cleaning accessories to tin and clean your soldering iron tips

When choosing a soldering station, consider the following:

Digital vs Analog Soldering Stations

Digital soldering stations offer real-time temperature readings that display on built-in LCD or LED screens. Conversely, analog soldering stations don't offer digital displays or provide precise measurements.

Analog stations can be a cost-effective way to start soldering, but if you're soldering components on PCBs, it's recommended to avoid analog stations because you won't be able to confirm the temperature at the tip before soldering.

Anti-Static (ESD-Safe) vs Non-Anti-Static

ESD-Safe soldering stations are grounded stations designed to protect against static or electrostatic discharge (ESD). ESD-safe soldering stations will be more expensive than non-ESD-safe stations.

However, if you're working with integrated circuits or most new electronic devices and circuit boards, you'll want an anti-static station. Otherwise, your projects run the risk of damage from static charges.

Wattage (Lead-Free vs Lead Solder)

To understand what wattage your soldering station needs, it's important to know what kind of projects you plan on using the station for.

If you intend to only use lead solder, you might be fine with a 50-watt or 60-watt station because leaded solder doesn't require as much heat to melt. However, lead-free solder requires hotter temperatures, so you'll need at least a 70-watt station.

Types of solder

Soldering is the process of using a filler material (solder) to join pieces of metal together. It is used to create a permanent connection between two or more electronic parts. Solder is a fusible alloy, or a low-melting-point metal alloy, that has been used for centuries to join metallic pieces.

There are several types of solder, which can be divided into the following categories:

Solder Types by Alloy

• Lead-based solder is the most common type, with a 60/40 tin/lead mix melting at around 180-190°C. It is widely used in electronics, plumbing, and more. However, due to environmental and health concerns, lead-free alloys are becoming more popular.
• Tin-antimony solder is a lead-free type of solder that contains 95% tin and 5% antimony. It is safe for water supply lines and is used in plumbing applications that experience extreme temperature changes and vibrations, such as refrigeration and cooling equipment.
• Copper-tin solder contains 97% tin and 3% copper. It is also lead-free and safe for water supply lines, and is designed for sweating copper and brass plumbing joints.
• Silver-bearing solder contains silver, copper, bismuth, and tin. It is lead-free and safe for water supply lines, making it ideal for low-lead brass applications.
• Tin-lead (Sn-Pb) solder is a eutectic alloy favoured for its low melting point of 183°C and excellent flow characteristics.
• Lead-free alloys (Sn-Ag-Cu) are widely used due to environmental concerns and offer strong joint integrity and moderate melting points.
• High-temperature alloys (Sn-Ag or Sn-Sb) are used in applications that demand robust thermal resistance and can withstand higher operational temperatures.
• Silver-alloy solder is used in silver brazing and operates at higher temperatures due to silver's high melting point.

Solder Types by Core

• Rosin-core solder is a less common type of solder that combines the metal alloy with a core filled with rosin, a natural pine tree resin. Rosin acts as a mild acid, cleaning the joining metals and allowing the solder to flow smoothly and create a strong bond. It is often used for electrical connections in electronics, circuit boards, and small-scale soldering projects.
• Acid-core solder is a special type of solder used for plumbing applications, particularly for soldering copper pipes and fittings. It uses a powerful acid flux to aggressively clean oxide layers from copper surfaces, allowing the solder to flow effectively and form a strong, clean connection.
• Flux-core solder is a broader category that includes any solder with internal channels filled with flux to aid in creating clean and efficient joints.

Other Considerations

When choosing a type of solder, it is important to consider the specific application and the thermal and mechanical demands it will require. For high-temperature environments, solders with higher melting points should be used. Additionally, the potential for galvanic corrosion or brittle caused by placing dissimilar metals in contact with one another should be considered when choosing solder blends.

Desoldering

Using a Soldering Iron

The simplest and easiest method to desolder components is by using a soldering iron. Here are the steps:

• Set the soldering iron to a temperature that can melt the solder.
• Heat the solder joint using the iron until it starts to melt.
• Nudge the pins using the iron and move the solder away from the joints.
• Pull the components out of the holes using pliers. Apply pressure at the tips of the components instead of their bodies to avoid damage.
• If you need to remove solder from holes, use a safety pin to suck out the solder.

Using a Desoldering Braid/Wick

• Choose the appropriate size of wick and soldering tip for the solder to be removed.
• Place the wick over the solder and the hot soldering iron over the braid.
• Place the tip at an angle that maximises heat transfer through the braid to the solder.
• Apply slight pressure and wait for the solder to melt.
• Remove the wick and the soldering iron at the same time.
• Once the wick is saturated with solder, trim it off and move to a new piece.

Using a Desoldering Pump

A desoldering pump is a small, high-pressure vacuum pump used to suck up molten solder. Here are the steps:

• Heat the solder you want to remove with a soldering iron.
• Press down on the plunger or squeeze the bulb of the desoldering pump.
• Place the tip of the pump against the molten solder.
• Release the plunger or bulb to suck up the solder. Some pumps have a release button.
• Remove the component and repeat the process if needed.
• Dispose of the solder inside the pump by pressing down and releasing the plunger repeatedly.

Using a Heat Gun

A heat gun is used to heat up the solder, allowing for the removal of components. Here are the steps:

• Turn on the heat gun.
• Hold the PCB firmly using a stand or pliers.
• Hold the tip of the heat gun against the solder until it melts.
• Remove the components using pliers.
• Be careful not to hold the heat gun against the board for too long, as it can damage the board.

Using Compressed Air

Compressed air can be used in two ways to desolder components:

• With a Soldering Iron: Heat the solder with the iron, then blast it with compressed air.
• Without a Soldering Iron: Turning a compressed air can upside down sprays out a freezing liquid solvent that super-cools the solder, making it brittle. Spray it on the solder and joints, then wrench the components off with pliers.

Safety tips

Before you start soldering, it is important to familiarise yourself with the safety precautions to ensure you don't hurt yourself or damage your work. Here are some essential safety tips to keep in mind when using solder:

• Always read the risk assessments and chemical safety information before starting any soldering work. This information should be easily accessible from your soldering station.
• Know what is in your solder. The composition may not be apparent from the reel label, so ask if you are unsure.
• Never touch the element of the soldering iron. It can reach temperatures of up to 400°C.
• When handling wires, use tweezers or clamps to hold them in place.
• Keep the cleaning sponge wet during use.
• Always return the soldering iron to its stand when you are not using it. Do not put it down on your workbench.
• Unplug the soldering iron and turn it off when you are finished.
• Wear eye protection. Solder can "spit", and you don't want any molten solder to accidentally fly into your eyes.
• Use rosin-free and lead-free solders if possible. Lead can have serious chronic health effects if ingested, and rosin can cause eye, throat and lung irritation, nose bleeds, headaches, and can aggravate asthma.
• Keep cleaning solvents in dispensing bottles.
• Wash your hands with soap and water after soldering.
• If you are handling solder directly, wear gloves to avoid lead exposure through your skin.
• If using rosin, ensure you are in a well-ventilated area and use an enclosed hood or tip extraction to vent fumes outside.
• Regularly test and maintain your extraction systems, keeping a log of filter changes.
• Do not solder if the extraction system is not working and report any issues immediately.
• Supervisors should inform users of the risks of soldering and ensure that controls are in place and used correctly.
• All those soldering should receive appropriate training and supervision.
• If you are soldering frequently or using rosin-containing solders, you should be referred to a safety officer for health surveillance.
• Do not use soldering irons with obvious damage to the body, cable, or plug.
• Ensure your soldering station is free of electrical cables to prevent damage from the heated tip.
• Use a grounded outlet and grounding prong to prevent short circuits.
• Work on a fire-proof or fire-resistant surface to reduce the risk of fire.
• Wear fire-resistant clothing that covers your arms and legs to prevent accidental burns.
• Know where your nearest fire extinguisher is and how to use it.
• If you do suffer a burn, run the affected area under cold water for 15 minutes. For deep or extensive burns, report to a first aider. For minor burns, cover the area with a plaster.
• Collect waste solder in a lidded container and dispose of it as hazardous waste.
• Place used solder sponges and contaminated rags in a sealable bag for disposal as hazardous waste.

Frequently asked questions