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Lab 4 - Intro to Soldering

09-25-2025

Overview

Soldering is a fundamental and important part of working with unmanned aircraft, its the process of joining components together with molten lead and tin to create a strong, reliable connection.

The focus of this lab was to practice soldering, and become familiar with the equipment used and safety steps taken when soldering. With a focus on completing two common types of joints. A lap joint, which is used to connect two wires together. And through-hole soldering on a PCB board, which is used to connect various electrical components to the board.

Being able to identify the difference between good and bad soldering is crucial. It is important that those working in this industry can create acceptable solder joints, in various different ways.

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Preparation for Lap Joint

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When soldering lap joints, multiple pieces of equipment are needed to properly and safely solder joints, this includes:

Safety Glasses : To protect molten solder from going into eye

Wire Strippers: Used to remove the insulator from the end of the wire without damaging internal copper strands of wire

Flush cutters: Used to evenly cut the length of the wire

Soldering Iron: This is the tool used to heat the solder onto components, it has an adjustable heat setting and a sponge to clean the tip of the iron of excess solder

Solder: A mixture typically using lead and tin on a core of rosin, used to create electrical joints between two conductors by joining them together with melted solder

Third Hand Tool (Helping Hands): If needed they are used to assist with holding wires or components and ease the process of soldering

Brass Wire Sponge: An alternative more abrasive surface to clean the tip of the soldering iron

Distilled water: Goes onto sponge located on lower part of soldering unit to dampen it for cleaning

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Soldering a Lap Joint

Lab Joint Procedure:

Prepare Wires by cutting the insulation of the end of the wire, about .25 inches.

Cleaned tip of soldering iron then tinned to ensure efficient heat transfer.

Placed Soldering Iron on surface of table and manipulated wire and solder to tin them.

Tinned ends of each wire, making it easier for them to connect when forming the lap joint.

Placed both ends of wire on top of each other, joining them with evenly applied heat from the soldering iron to form the lap joint connection using solder.

Lap Joints Attempts

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Example of an acceptable lap joint: With an even layer of solder over entire joint; wires lay flat on top of each other; and the insulation and solder is not burned into joint.

Example of an acceptable lap joint: With an even layer of solder over entire joint; wires lay flat on top of each other; and the insulation and solder is not burned into joint.

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Example of poor quality lap joint: Insulation is burned; solder is unevenly coated on joint; wires are not directly on top of each other and have a slight cross overlap.

Example of poor quality lap joint: Insulation is burned; solder is unevenly coated on joint; wires are not directly on top of each other and have a slight cross overlap.

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Preparation for PCB Through-Hole Soldering

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When soldering components onto a PCB, it is important to take the necessary steps to make sure all solders are clean and adhere strongly. Multiple components are used such as:

Printed Circuit Board (PCB): This is the base that other components are soldered onto. Many different types of components can be added to one and perform various tasks

Resistors: This is the part that is soldered onto the PCB, a resistor is an electrical components that limits the flow of electrical current in a circuit

Solder: On PCB’s very little solder is needed to create a good electrical connection

Third Hand Tool (Helping Hands): can be used to firmly hold and manipulate the PCB board while working on it

Soldering Iron + Cleaning tools: these are used in the same way throughout soldering, melting solder and cleaning the tip of the Iron to get replicable results

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Soldering a Through-Hole joint on Printed Circuit Board (PCB)

Through-Hole Soldering Procedure

Insert component (resistor) so that the conductors are resting straight in the PCB holes

Avoid cutting excess conductor from the resistor as this can be done later.

Secure the PCB into the helping hands tool if needed, this will keep the PCB from moving while trying to solder onto it.

Press the tip of the soldering iron against the conductor of the resistor, and the conductor ring around the PCB hole for a second or two. This heats the components and prepares them for solder.

Smoothly feed solder into the PCB hole with the conductor centered in it, until a “volcano” like shape is formed between the board and the conductor with the solder

Through-Hole Attempts

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Overall these through-hole joints could use some more practice, they are oversized and use too much solder. They are not quite the "Volcano" shape that is needed.

Overall these through-hole joints could use some more practice, they are oversized and use too much solder. They are not quite the "Volcano" shape that is needed.

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Conclusion

With this being my second time soldering, I further learned the importance of proper heat application and the amount of solder to use.

However I had never soldered on a PCB board before. I found this to be more difficult than the lap joint. This is because I had trouble with getting the solder to flow at first, but after a few attempts and some advice from others, I learned how to get the solder to stick to the board. Overall this was a good learning experience with solder and how to use it properly and safely

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