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(This guide is based on 1991 textbook "Electronic Techniques--Shop Practices and Construction" 4th ed., by Villanucci, et. al.. Perhaps of less use today; nevertheless, it serves as an important historical reference of pre-computer and CAD-less methods.)
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15. PCB SOLDERING
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Completely revised and updated [ca. 1991], this guide is designed for any electronic shop program. The material is logically presented to help the beginning technician to become competent in all aspects of electronic design and fabrication techniques. The guide is a practical and realistic approach for the development and improvement of skills necessary for the planning, layout, and construction of electronic equipment.
Among its key features:
• Learning objectives at the beginning of each section
• Technical tables, flow charts, and graphs for double-sided and multilayer printed circuit board fabrication
• Employs current solid state devices, including integrated circuits, with the use of a stereo amplifier system as the motivating teaching vehicle which appears pictorially throughout the text
• Sections 10 through 21 are devoted exclusively to printed circuit design, fabrication, quality control inspection and assembly
• Detailed material on plated-through-hole technology used in the manufacture of double-sided and multilayer printed circuit boards
• Complete information on the design and fabrication of four-layer (power/ground) multilayer printed circuit boards
• Information on both destructive and nondestructive quality control testing of printed circuit boards
• Over 500 detailed illustrations and photographs
• Projects to reflect state of the art equipment
• Material on wave soldering, surface mounted technology, and computer-aided design
The electronic packaging industry continues to undergo rapid changes. Electronic Techniques: Soldering, Shop Practices and Construction was prepared to keep pace with these changes in order to acquaint the student further with current industrial processes.
Owing to the wide acceptance of this guide, much of the material has been retained. To strengthen and update the guide, the following material has been added:
1. A new section devoted exclusively to surface-mounted technology, including methods of assembly and soldering.
2. A section on computer-aided design (CAD) of printed circuit boards.
3. Thermal profiles of soldering irons and the wave solder process using a computer-based data acquisition system.
4. Introduction of modern instruments such as the densitometer and the radiometer for PCB process controls.
5. Design criteria for automatic component insertion equipment.
6. New projects have been added to reflect the state of the art and to generate student motivation.
7. The end-of-section exercises have been expanded to include five basic types: questions, multiple choice, true or false, matching, and problems.
The development of new devices for high-density packaging in conjunction with modern printed circuit technology has brought about more sophisticated construction and packaging techniques that require today’s technician to develop special skills. It is the purpose of this fourth edition to continue to present a practical and realistic approach for developing these skills in planning, laying out, and constructing electronic equipment.
This text has been designed to fulfill the needs of any electronic shop program. The material presented is directed toward educational institutions such as technical-vocational schools, technical institutes, and junior colleges, as well as industrial and military training programs.
The training of a skilled craftsman requires not only clear and detailed explanations, but also visual and graphic aids. For this reason, over 500 figures and drawings have been included to illustrate fundamental techniques used in electronic design, construction, and packaging. In addition, many exercises have been included to aid in the thorough understanding of these basic concepts.
Although the design and construction techniques are presented in a logical sequence, individual sections may be studied independently. No prerequisite knowledge of electronic circuits is necessary to understand the material presented, although a deeper insight may be realized if the technician has a fundamental background in electronics.
A high-fidelity stereo amplifier system is the motivating teaching vehicle and appears pictorially throughout the guide. Its function is to generate interest and to present in a logical sequence the fabrication techniques necessary to construct any package or system. It is not necessary to build the amplifier system in order to derive maximum benefit from the text. This approach allows complete flexibility to permit instructors to select other included projects. They may, in addition, use any of their own choosing.
Section 1 is a discussion of the factors that must be considered in pack aging any electronic system. Section 2 introduces the high-fidelity stereo amplifier system and its package design. In Section 3, preliminary considerations of the package are converted to detailed engineering drawings and sketches. The layout, fabrication, and finishing of sheet metal chassis elements are covered in Sections 4 through 9. Sections 10 through 15 provide detailed information on designing and fabricating single-sided printed circuits by the print- and-etch technique, assembly, and soldering. In these sections, all pertinent information on available printed circuit materials and techniques are presented to serve as working guides that will allow the technician to become proficient in single-sided printed circuit technology. Also included are CAD layout, photographic processes, and hardware and component assembly. These sections are also sufficiently detailed to provide the necessary information for establishing a safe and economical printed circuit prototype laboratory. Section 16 presents material on double-sided printed circuit artwork design using the diazo process for making positive phototools and includes use of the densitometer. Sections 17 through 19 cover the plated-through-hole processes, the print- plate-and-etch technique, and the use of dry-film photo-resist. Section 20 pro vides basic design and fabrication procedures for multilayer boards. Section 21 presents detailed information on surface-mounted technology, including component assembly and soldering. Visual inspection and testing procedures of printed circuit boards using microprocessor, Caviderm, and microsectioning techniques are presented in Section 22. Assembly, wiring, and harnessing techniques are covered in Sections 23 through 25 in order to combine the printed circuit boards and the chassis elements into a completed system. Section 26 contains a selection of projects to (1) further develop student interest and (2) provide practice in developing the skills discussed in this guide.
Modern industrial printed circuit board fabrication processes require the use of hazardous chemicals as described in this guide. The authors cannot emphasize strongly enough that the handling, use, shipping, storage, and disposal of these chemicals be performed under supervision by people who are trained in this area and who are familiar with OSHA and EPA regulations. This is a learning text and, as such, describes in detail the chemical processes required.
However, in no way does it provide the training and conditions for handling these chemicals.