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Master the Art of PCB Design: Your Complete Step by Step Guide to Schematic & Layout Techniques using KiCAD
Sun Jan 14, 2024
Are you interested in designing a PCB for your project? Do you want to learn the procedures, the techniques, the guidelines & the tools for designing a PCB ? Or are you looking to acquire practical skills to enhance your expertise and knowledge in electronics?, then this blog is for you. We give you an introduction on the topic as well as pointers to learn them. We discuss,
What is a PCB?
All electronic products use a board to mount and interconnect the electronic components
according to a circuit which is specific to the product. This board is the PCB aka printed circuit board.
What is PCB design?
PCB design is the process of turning an electronic circuit into a format that could be interpreted by the PCB manufacturers for fabricating the PCB. This is done with the help of computers & EDA software tools.
What is PCB made of?
A PCB is made from copper clad laminates. Copper cladding could be present on one side or both sides of the insulating dielectric substrate. Depending on the materials used for the dielectric substrate and the ways of laminating and connecting the conductive material there are different variants of PCB boards. Manufacturers fabricate the PCB according to the circuit specified, the material specified & the number of layers specified in the design.
When is PCB designed?
A PCB could be designed during prototyping, the final stage or even as revisions of the final product. The design of the PCB has a strong impact on the mechanical and electrical performances of the final product.
Who designs the PCB?
For some designers, the PCB design is easy but for many others the process of designing and laying out a PCB can be a very daunting task. Companies usually have their own dedicated PCB design departments. For simpler and low performance circuits, a quick design could be done by anyone in the development team who has a basic know how of using the software tools. However complicated designs involving hundreds of components and thousands of tracks that meets a whole host of physical and electrical requirements warrant a great deal of knowledge, talent & patience. To make matters even worse, PCB traces have resistance, inductance, and capacitance, just like a circuit. All these affect the performance in case of high speed digital, RF & analog circuits. A poor design ignoring these elements will render the PCB useless. Proper PCB design is very often an integral part of a product design. In PCB design, there are many rules as well as good practices to be followed. PCB design is a highly creative process. No wonder why PCB layout is considered as an art work by many designers.
Before delving deeper into PCB design, let's take a look at some of the alternate or earlier methods used in implementing the circuit connections.
Point to Point Wiring
This was a widely used method for connecting electronic components before PCB. Electronics devices were constructed with component leads soldered directly to each other. Connecting components in this way means there is less distance between them and therefore less resistance in the circuit. Since the signal does not have to travel as far, it results in the cleanest and strongest signal path possible. For this reason, some Hi-Fi audio equipment and amplifiers are still built using point-to-point style wiring. The major downside of this method is the layout looks complicated. Its hard to maintain or rework on such a layout.
Tag board, Turret board, Eyelet board
To overcome the complex layout of point to point wiring , terminal strips were designed. Here the components are laced through or laced around metal terminals that come on either strips or boards. Everything is then connected with wires to where they need to go. The layouts look more uniform and also decreases production time. This method is used even today in certain cases like prototyping where only a few components are used and also in power electronics where the components are bulky and serviceability is a major requirement. The disadvantage is it cannot be automated. All soldering work has to be done by hand.
Its a generic board used in implementing circuit connections. It has wide parallel strips of copper cladding running in one direction all the way across one side of the substrate. The strip has holes with a spacing of 0.1 inches/(2.54 mm). Strip board is also known by the name vero board. Strip board is mainly used in prototyping as well as in some cases, as final PCB if the component count is very few. Strip boards are available in various dimensions. They are very economical.
Perf board is a variation of the strip board. It is also known as DOT PCB. Here each hole is electrically isolated from each other. This method also cannot be automated. All soldering work has to be done by hand.
The years before CAD
Paul Eisler is credited with the invention of the printed circuit board. He was an Austrian inventor born in Vienna. Eisler patented a method of etching copper circuits onto a layer of copper foil laminated to a non-conductive base. This was in the 1940s. Towards the end of 1950s printed circuit boards became mainstream with the transistor radio. Printed circuit boards of those times were designed by hand without the use of computers until about 1980s. How did they do it? A host of tools were needed before embarking on a PCB design in those days such as a drafting table, a light table, mylar sheets, pencils, templates and a few more. The first step was to draw the schematic. The schematics were drawn by electronics draftsmen who were specialized in the trade. The drawn schematics were checked for accuracy and passed onto the layout designer. The layout designer had a booklet of component decals to be used for the layout. It was either sticker or sometimes had to be drawn by hand. These decals were used for standard component packages and dimensions. After the component layouts were done, the wiring is done using coloured pencils. Once the layout is complete, photograph of each layer is taken and send to the manufacturer for fabrication. The period before CAD was a tough one. This method was tedious and costly. Once CAD took off, manual drawing became obsolete.
A PCB consists of a blank base material also known as the substrate or core or board. A blank base material coated with copper on one or both sides is known as a copper clad board. The substrate is usually 1.6mm thick. Other common thicknesses include 0.8mm and 2.4mm. There are many types of PCB substrate material. The most common one is a standard woven epoxy glass material known as FR4. Higher grade base materials like Teflon are also available, but are only used for designs that specifically need them. Cheaper grade materials like phenolic base and CEM-1 are used when cost is a factor. However they are not suitable for fine tolerance designs. The dielectric constant of the core is an important parameter. It is used for calculating high speed transmission line parameters and other effects. An FR4 PCB can typically have a dielectric constant ranging from under 4, to almost 5. A multi-layer board is made up of various individual boards separated by Preimpregnated Bonding Layers, also known as “prepreg”. The prepreg and core are two different parts of the PCB. The core is the FR4 material with copper traces on one or both sides. The prepreg bonds two copper layers together or binds one copper layer and a core. In doing so it retains the separation between the two materials being bonded. The prepreg material is impregnated with a resin, where the resin is hardened but left uncured. Two cores could be stacked on each side of a prepreg laminate. On exposing the stack to heat causes the resin to begin bonding to the adjacent layers.
So how do you design a PCB?
What are the tools used?
How do you choose the parameters for design?
How do you design a multi layer PCB?
How do you employ EMC design techniques in PCB design?
We at CODECIRCUITRY offers the course "Learn PCB Design and Layout Techniques" for you to get started in PCB design. This course covers all these topics. The is course is a blend of both theory and practicals. This is a step-by-step course on printed circuit board design with information suitable for beginners. This course is for anyone who wants to design printed circuit boards on their own. Knowledge in basic electronic theory is a prerequisite to fully grasp certain concepts.
The entire course is divided into 7 modules. Module 0 to Module 6.
Expected outcomes include the following:
PCB Design is an interdisciplinary skill involving both mechanical and electrical domains. At one point you might be measuring the dimensions. At another instant you possibly could be calculating the impedance or current flow or temperature rise. Some consider PCB design to be an art. Designers try to express them by placing the components aesthetically. You should be very creative and technically sound to make the PCB aesthetically pleasing as well as highly functional. The process of transforming an idea into a PCB architecture has several stages with well defined steps. Each new PCB is an opportunity to be creative as well as improve your technical skills . Our course aims to equip you with technical knowledge on PCB design, help you build multi layer PCB and thus launch yourself to a platform from where you could explore the advanced concepts on your own. We welcome you to join our course "Learn PCB Design and Layout Techniques".
Our vision is to create a platform where anyone could upskill as well as build their knowledge on hardware & firmware development through industry relevant courses in electronics, programming & mathematics at affordable prices. Driven by our passion for technology, we aim to bring in innovative hardware products and software applications at affordable prices. We also offer firmware development and guidance services in Beaglebone, Nvidia Jetson, Raspberry Pi and Arduino.