SOLDERING and the REPAIR of PCBs
COURSE 560: 2 DAYS: Max 8 Candidates
This course provides all the skills necessary to work on modern electronic printed circuit boards. It is intended for candidates who have an understanding of electronics principles, but have little or no experience of working on modern electronic systems or equipment down to component level. It complements the Electronics Faultfinding (Course 570)
Throughout the course best practice will be observed as described in International Standard IPC-A-610D.
PARTICIPANTS
This course is essential for anyone involved in repair and maintenance of electronic systems and equipment, including those who are responsible for supervising the repair and quality of electronic systems and equipment.
COURSE PRESENTATION
This important subject is presented throughout by reference to the IPC 610 Standard and generous amounts of practical work. Comprehensive notes are provided along with all the necessary soldering and rework equipment.
COURSE OBJECTIVES
On completion of the course, participants will have a thorough understanding of the requirements involved in the repair and maintenance of printed circuit boards to the IPC-A-610D Standard. Candidates will:
- apply safe working practices
- understand the problems of electrical over stress (EOS) and electrostatic discharge (ESD)
- Identify the various types of components used: Through-hole, SMT QFP DIL LCC Gull-Wing etc
- determine component values from case markings
- understand the IPC-A-610 Standard
- prepare wires for soldering and looming
- select the correct grades of solder
- understand the use of fluxes and cleaning solvents
- make solder joints to IPC-A-610
- remove and replace solder joints and components on pcbs using: solder wick, soldering irons, heated tweezers and hot air rework stations
- inspect PCBs to a high level of workmanship (IPC-A-610D).
Successful completion of the course leads to the award of the Technical Training Solutions Competence Certificate 560 ‘Soldering and the Repair of PCBs’
What do candidates on the Soldering and the Repair of PCBs course actually do?
We begin the course with a review of the components used in industrial, commercial and military electronics. Then an overview of the substrate materials used to produce the circuit boards. The main emphasis is on the most common material – fibre reinforced (FR4), but others such as ceramic and metal clad poly-imide are also discussed.
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The management of static electricity (ESD) and thermal shock is demonstrated, and candidates are provided with the necessary tools to enable best practice to be used. Work where ESD could present a problem is done at an ESD workstation. The candidate's notes contain details on how such a workstation can be constructed at their own place of work.
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The various methods of minimising exposure to noxious fumes is studied and proper fume extraction is used whilst soldering on the rework station. A variety of industry-standard soldering irons and rework stations are used on the course, allowing candidates to gain practice using a range of different standards of iron.
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Candidates practice making solder joints of wires to terminal pins in accordance with best practice. Cable forms are then laced together to ensure that mechanical support is provided. Students then inspect each other's work with respect to IPC-A-610D.
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We then practice pre-forming component leads to minimise stress from vibration during the operational life of the circuit board. Vertical and horizontal mounting of components is discussed and practiced.
Excessive heat can seriously damage circuit boards, especially flexible mylar film and multi-layer circuit boards, therefore the importance of temperature control and limiting heat exposure is stressed throughout the course.
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Candidates spend time applying flux, aligning components and making solder joints to a range of leaded components before moving on to SMT devices. Emphasis is placed upon the quality of each joint - candidates are given examples of good / bad joints and how to inspect work to the Standards.
A range of SMT components are reviewed and the merits of the various connection methods are discussed, e.g. flat ribbon, gull wing, J-lead and ball-grid-arrays etc. Candidates spend time attaching all of the component types except the BGAs (these require specialist equipment and are beyond the scope of this course).
Throughout the course we refer to the course notes which provide lots of useful information about soldering and desoldering as well as the candidates' instructions for all the practical exercises that we do. The following are some example pages from the soldering course notes:
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Flux and debris removal is an important part of the inspection process, and requires the use of solvents. Best practice and health and Safety is fundamental to all Technical Training Solutions' courses, therefore the correct solvents are used to minimise the personnel and environmental risks.
The repair of circuit boards is also given serious consideration, as the PCB is often the most expensive part of the system. Candidates are shown several ways to remove components while minimising damage to delicate circuit board tracks.
Solder removal is practiced where solder bridges occur, or excessive solder has been used.
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Where track damage in unavoidable, the methods of repair are practiced. This part of the course is also valuable to those who may have to modify circuit boards because of errors or obsolete components.
The handling and application of epoxy resins and silicone based elastomers with regard to PCB repair is covered in some depth along with the application of conformal coatings.
Throughout the course the instructor will make a continuous assessment of the candidate's progress, and because of the small group size close guidance is ensured. Each candidate will produce a test piece in order to demonstrate their competence in the assembly and repair of electronic equipment. Candidates then inspect a range of PCBs, making extensive reference to IPC 610, noting any deviations.