Basic Electricity - Senior Secondary 1 - Soldering

TERM: 3^RD TERM

WEEK SIX

Class: Senior Secondary School 1

Age: 15 years

Duration: 40 minutes of 5 periods each

Date:

Subject: BASIC ELECTRICITY

Topic: SOLDERING

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

I.) Define soldering

II.) Describe the principles of soldering

III.) Define flux

IV.) State the types of flux

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures,

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

NOTE

SOLDERING

Soldering is a process of joining two or more metal components together using a filler metal called solder. The solder is melted and then allowed to solidify, forming a bond between the components.

Principles of soldering

1. Heat Transfer: Heat is applied to the joint area using a soldering iron or torch, melting the solder and allowing it to flow into the joint.
2. Surface Preparation: The surfaces to be soldered must be clean and free of contaminants such as dirt, oil, or oxidation to ensure a strong bond.
3. Capillary Action: Molten solder flows into the microscopic irregularities of the metal surfaces due to capillary action, forming a strong mechanical and electrical bond.
4. Metallurgical Bonding: Solder forms a metallurgical bond with the metal surfaces, creating a permanent joint when cooled.
5. Fux Application: Flux is often used to remove oxides from the metal surfaces, prevent oxidation during soldering, and improve wetting and flow of the solder.

Flux

Flux is a chemical compound used in soldering to facilitate the soldering process by:

- Removing oxides from metal surfaces, ensuring proper wetting and bonding.

- Preventing oxidation of the metal surfaces during soldering, maintaining clean surfaces for solder adhesion.

- Improving the flow and spreading of solder, enhancing the formation of strong, reliable joints.

Types of flux:

1. Rosin Flux: Derived from pine trees, rosin flux is the most common type used in electronics soldering. It comes in different formulations, such as rosin-core solder and liquid flux.

Composition: Derived from natural resin extracted from pine trees, rosin flux contains organic compounds such as abietic acid.

2. Water-Soluble Flux: This type of flux is easily cleaned with water after soldering and is often used in applications where residue removal is essential, such as PCB assembly.

Composition: Contains water-soluble organic acids, activators, and inhibitors. Common ingredients include organic acids like citric acid or hydrochloric acid.

3. No-Clean Flux: Designed to leave minimal residue after soldering, no-clean flux is suitable for applications where post-soldering cleaning is not possible or practical.

Composition: Contains synthetic resins, organic acids, and activators. The residue left after soldering is minimal and does not require cleaning under normal operating conditions.

4. Activated Rosin Flux: This flux type contains additional activators to improve solder wetting and bonding, making it suitable for challenging soldering situations or materials like stainless steel.

Composition: Similar to rosin flux but with added activators like hydrochloric acid or amine hydrochloride.

EVALUATION: 1. Define soldering

2.   What is flux?
3. Briefly discuss the principles of flux
4. State the composition of the following flux. I. Activated room flux. II. water soluble flux. III. Rosin flux

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively