Class: Senior Secondary School 1 (SS1 / SSS1)
Term: 3rd Term
Week: 7
Age: 15 years
Duration: 45 minutes
Subject: Radio, Tv & Electronics
Curriculum Theme: Trade
Previous Lesson: Demodulation: Definition of Demodulation And Types.
Topic: SOLDERING AND DESOLDERING IN ELECTRIC CIRCUITS
Subject Matter: Soldering techniques, Desoldering techniques, Safety precautions

Specific Objectives

By the end of the lesson, pupils should be able to:

Cognitive Domain:

Define soldering and desoldering.
Explain the basic techniques involved in soldering.
State important safety precautions for soldering and desoldering.

Affective Domain:

Appreciate the importance of safety when working with electrical tools.
Demonstrate carefulness while handling soldering equipment.

Psychomotor Domain:

Identify the tools used for soldering and desoldering.
Practice correct hand movements for effective soldering and desoldering (simulated or actual).

Work cooperatively when sharing tools during practical sessions.
Follow instructions for safe workshop practices.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum for Basic Technology.
Lagos State Unified Scheme of Work for Senior Secondary Schools.
Macmillan Introductory Technology for Senior Secondary Schools 1.
https://www.nigeriancurriculum.com/radio-tv-electronics
https://www.education.gov.ng/curriculum-resources

Instructional Materials

The teacher will teach this lesson with the aid of:

Soldering iron
Safety goggles
Solder wire
Desoldering pump/braid
Circuit board with components
Safety gloves
First aid box

Rationale for the Lesson

This lesson helps pupils to understand practical skills for joining and removing electronic components, which is essential for repairing and building electronic circuits. It also teaches pupils how to work safely with tools that generate heat, preventing injuries in practical applications.

Prerequisite/Previous Knowledge

Pupils should have basic knowledge of electrical components and simple electrical circuits.

Lesson Content/Board Summary

SOLDERING AND DESOLDERING IN ELECTRIC CIRCUITS

What is Soldering?

Soldering is the process of joining two or more metal items together by melting and flowing a filler metal (solder) into the joint. The solder has a lower melting point than the adjacent metal parts, which remain unmelted. In electronics, solder is used to form electrical connections between components and circuit boards.

Soldering Techniques

Effective soldering involves several steps to ensure a strong and reliable joint:

Preparation: Clean the surfaces to be joined and ensure components are correctly placed.
Heating: Heat both the component lead and the circuit board pad simultaneously with the soldering iron tip.
Applying Solder: Once heated, apply solder to the joint, not directly to the iron. The solder should flow smoothly and completely around the joint.
Cooling: Remove the solder and then the iron, allowing the joint to cool naturally without disturbance.
Inspection: Check for a shiny, smooth, cone-shaped joint, indicating a good solder connection.

What is Desoldering?

Desoldering is the process of removing solder from a joint, usually to remove or replace an electronic component. It involves heating the solder until it melts and then removing the molten solder.

Desoldering Techniques

Common methods for desoldering include:

Using a Desoldering Pump (Solder Sucker):
- Heat the solder joint until the solder melts.
- Quickly place the nozzle of the desoldering pump over the molten solder and release the plunger to suck up the solder.
- Repeat if necessary until most solder is removed.
Using Desoldering Braid (Solder Wick):
- Place the desoldering braid over the solder joint.
- Heat the braid with the soldering iron. The molten solder will be absorbed by the braid through capillary action.
- Remove the braid and the iron once the solder is absorbed.

Safety Precautions for Soldering and Desoldering

Working with soldering equipment requires adherence to safety rules to prevent injuries:

Always wear safety goggles to protect your eyes from splashes of molten solder.
Work in a well-ventilated area to avoid inhaling solder fumes, which can be harmful.
Ensure the soldering iron is placed in a proper stand when not in use to prevent burns or fires.
Avoid touching the hot tip of the soldering iron.
Use appropriate tools like tweezers or pliers to hold components, rather than fingers.
Keep a fire extinguisher or a wet cloth nearby in case of accidental fires.
Wash hands thoroughly after soldering to remove any lead residue (if using leaded solder).
Disconnect the soldering iron from the power supply when finished.

Teaching Methods/Instructional Techniques

Discussion, Lecture, Demonstration, Question and Answer, Visual Aids

Instructional Procedures

Step 1: Introduction

Time: 5 minutes
Teaching Skill: Set Induction
Teacher’s Activity: The teacher greets the pupils, reviews the previous lesson briefly, and then asks pupils if they have ever seen electronic devices being repaired or components being joined together. The teacher introduces the topic by explaining that joining and removing electronic parts is done through soldering and desoldering.
Pupils’ Activity: Pupils respond to questions and listen attentively.
Learning Point: Pupils are introduced to the topic and relate it to real-world applications.

Step 2: Presentation of Soldering

Time: 10 minutes
Teaching Skill: Explanation/Demonstration
Teacher’s Activity: The teacher defines soldering and explains its importance in electronics. The teacher then explains the step-by-step techniques for good soldering, emphasizing proper heating and solder application. The teacher may use a diagram or a simple visual aid to illustrate the process.
Pupils’ Activity: Pupils listen, ask questions, and take notes.
Learning Point: Pupils understand the definition and basic techniques of soldering.

Step 3: Demonstration of Soldering

Time: 5 minutes
Teaching Skill: Practical Demonstration
Teacher’s Activity: The teacher demonstrates the soldering process using a soldering iron, solder wire, a simple circuit board, and a component, reiterating the techniques explained in Step 2. If actual demonstration is not possible, a video or detailed step-by-step pictures will be used.
Pupils’ Activity: Pupils observe the demonstration carefully.
Learning Point: Pupils visually grasp the practical application of soldering techniques.

Step 4: Presentation of Desoldering

Time: 10 minutes
Teaching Skill: Explanation/Discussion
Teacher’s Activity: The teacher defines desoldering and explains when it is necessary. The teacher then explains the two main techniques: using a desoldering pump and using desoldering braid, detailing the steps for each method.
Pupils’ Activity: Pupils listen, engage in discussion, and write down key points.
Learning Point: Pupils learn the definition and various methods of desoldering.

Step 5: Demonstration of Desoldering

Time: 5 minutes
Teaching Skill: Practical Demonstration
Teacher’s Activity: The teacher demonstrates the desoldering process using a desoldering pump or braid on a previously soldered joint, showing how to effectively remove solder.
Pupils’ Activity: Pupils observe the demonstration.
Learning Point: Pupils observe the practical application of desoldering techniques.

Step 6: Safety Precautions

Time: 5 minutes
Teaching Skill: Emphasizing/Instruction
Teacher’s Activity: The teacher discusses and lists the important safety precautions that must be observed when performing soldering and desoldering operations. The teacher explains the reasons behind each precaution, such as wearing safety goggles for eye protection and working in a ventilated area for fume safety.
Pupils’ Activity: Pupils listen, contribute to the discussion, and note down the safety rules.
Learning Point: Pupils understand and learn crucial safety measures for practical electronics work.

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

Define soldering and desoldering.
Mention two important techniques for effective soldering.
State three safety precautions to observe while soldering.
How is a desoldering pump used to remove solder?

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 2 minutes
Teaching Skill: Summarization
Teacher’s Activity: The teacher summarizes the key points of the lesson, reiterating the importance of proper techniques and safety. The teacher assigns homework, asking pupils to list the tools required for soldering and desoldering.
Pupils’ Activity: Pupils listen to the summary and copy down the homework.
Learning Point: Pupils consolidate their understanding and prepare for further learning.

Lesson Keywords

Soldering – The process of joining metal parts using a melted filler metal (solder).
Desoldering – The process of removing solder from a joint.
Solder – A metal alloy with a low melting point used to join electronic components.
Soldering Iron – A tool used to heat solder to its melting point for joining components.
Desoldering Pump – A tool used to suck up molten solder.
Desoldering Braid – A braided copper wire used to absorb molten solder.

Differentiation

For pupils who grasp concepts quickly, the teacher can challenge them to identify different types of solder or advanced soldering techniques. For pupils needing more support, the teacher can provide simplified diagrams, extra verbal explanations, and pair them with stronger pupils for peer learning during practical demonstrations.

Note for teachers using this lesson plan

Teachers should emphasize practical demonstration and safety throughout the lesson. If actual soldering equipment is not available, visual aids like videos, detailed diagrams, or virtual simulations can be used effectively. Ensure all safety precautions are clearly understood and followed, especially regarding eye protection and ventilation. Encourage pupils to ask questions and practice the steps mentally.