PCB Design
Where are PCB used?
PCBs are most often associated with computers, they can be found in many other electronic devices, such as TVs, Radios, Digital cameras and Cell phones. In addition to their use in consumer electronics and computers, different types of PCBs are used in a variety of other fields, including: Medical devices.
What is PCB design?
Printed circuit board (PCB) design brings your electronic circuits to life in the physical form. Using layout software, the PCB design process combines component placement and routing to define electrical connectivity on a manufactured circuit board.
Popular PCB design software
Autodesk Eagle
Eagle is ostensibly one of the most well-known schematics and PCB design software. Autodesk Eagle contains a schematic editor, for planning circuit graphs and a PCB layout editor for designing PCBs. It provides component placement, PCB routing, comprehensive library content, a thriving community, and some more. It is accessible for Linux, Mac and Windows.
PCB Artist
PCB Artist is a dependable programming tool for electronics engineers searching for an intuitive, easy to utilize the solution. Electronics engineers choose PCB Artist as it assists save time and money. Some of its key features are free Gerber format files; parts list reports in CSV, integrated schematics and design rule check error report between selected items.
Protel( Altium Designer)
The company portel introduced the circuit design software (CAD) PROTEL in the late '80s, which deserved high ranking among many EDA and circuit designers. The designer has been now released with new features that aim to improve the overall user experience and its smoothness. The arbitrary-angle routing is the function which is newly introduced to complete the escape routing of dense BGA packages. Besides, its routing optimization processing is also improved with other enhancements.
Zenit PCB
Zenit PCB is an extraordinary PCB layout design software tool which is intended to create a professionally printed circuit board (PCB). It is adaptable and easy to use CAD programs to allow finishing the project in a short time.
Tiny CAD
It is the program which is designed to draw circuit diagrams. It comes with symbol libraries to get you started the easy way. It is simple to print your designs, and you can use TinyCAD to publish your drawings by copy-paste method to a word document or saving as a PNG bitmap for the web. Some of its features are; flat or hierarchical schematic entry, convenient support for embedding graphical images in drawings and many popular PCB layouts compatible netlist formats.
Ultiboard
Ultiboard is printed circuit board design and layout software which integrates with Multisim to accelerate PCB prototype development. It offers efficient PCB design and routing with a customizable environment. Its flexible tools help place parts and copper with manual precision to define critical board elements. Besides, the advanced spreadsheet view, design wizards, and toolbox allow you to easily manage and define any board layout.
PADS( Power PCB)
PADS is described to be the best EDA for its easy-to-use and easy-to-learn feature. It can be called out as a king of CAD on the low side. It is the most popularly used EDA in the market, which is also suitable for small companies. It supports the complete PCB design process which covers a full range of functions from schematic netlist import to final production file (Gerber), bill of materials and assembly file.
Osmond PCB
Osmond PCB is a design software tool for electronics engineers using Macs. The tool provides the user with flexibility and power and eliminates artificial restrictions to enable the design of board of any shape and size with as many layers as needed. Some of its features are; spatial resolution of 10 nanometers for precision, supports both metric and imperial unit, integrated parts editor for defining new part types or modifying existing part types.
KiCAD
KiCAD is an open-source and cross-platform electronic design automation suite which includes a schematic editor for editing and creating schematic designs. A PCB editor makes professional PCB layouts with up to 32 copper layers and a 3D viewer that can be used to inspect the design in 3D form. It is entirely free, and no paywall is needed for using some features. It is available on Linux, Mac and Windows.
Easy EDA
EasyEDA is a tool that provides a powerful schematic capture, library designer, PCB editor, a project management tool and a team collaborator. It allows educators, electronics engineers, makers, students and enthusiasts to share and design their projects. It is a design tool that integrates LCSC components catalogue and JLCPCB PCB service, helping users save time to make their ideas into real products.
The above mentioned are some of the software which is recommended to try in 2021.
Various Steps in PCB Design and Manufacturing
Step 1: Requirement analysis and Component selection
The first step in PCB design is to analyze the requirement and select the appropriate components such as processor, power supply. Create a blueprint that fulfills all the requirements.
Step 2: In-System Front end design
PCB layout is initially designed using a PCB design software. Altium Designer, Autodesk EAGLE, KiCad EDA, OrCAD are some commercially available software used for PCB design. The output of this design is usually in the form of a PCB schematic Gerber file. Gerber file encodes information including copper tracking layers, drill drawing, component notation, and other parameters.
Step 3: Photo tool Initiation
Next step is to run Design for Manufacture (DFM) check before circuit boards fabrication starts. This is to avoid any discrepancies in design. After this, a photo film is made to image the PCB using a laser printer/plotter. Different layers of the PCB photo film are aligned by punching precise registration holes in each sheet of film. The film is created to help in creating a figure of copper path.
Step 4: Printing the inner layers
The substrate, usually a composite epoxy substrate is taken, cut, cleaned and dried. Copper is pre-bonded on both sides of the substrate. Cleanliness of the panel is the most important factor to avoid short or open circuit errors. The copper is coated with a layer of photoresist, which then treated with UV light to harden it. The film formed in the previous step is placed over the copper layer and aligned using pin positions.
Later the panel is again UV treated. The dark areas on the film do not allow UV light, thus the areas below dark areas of the film are not hardened. While the light areas that are meant for copper wiring are hardened.
Step 5: Etching out the unwanted copper
The panel is then washed with an alkaline solution to wash away unhardened copper material. The desired copper layer is fully protected beneath the hardened layer of photoresist.
Next, the photoresist that is over the copper layer is also removed. This, in turn, leaves only the required copper layer intact.
Step 6: Register punching for layer alignment
The different layers are aligned and optically punched to create registration holes. This will align the inner layers to the outer layers.
Step7: Automated optical inspection
After lamination, it is impossible to sort out errors in inner layers. Hence the panel is subjected to automatic optical inspection before bonding up and lamination. The machine scans the layers using a laser sensor and compares it with the original Gerber file to list out discrepancies, if any.
Step 8: Layer up and Bond
The layers of the PCB panel are bonded together by aluminium press plate. For double and multi later PCB further copper foils are pressed over original layers with insulating layers placed in between and the etching process is repeated. Finally, all the layers are laminated together to provide the final shape to the PCB panel.
Step 9: Drilling
The PCB stack is then drilled for holes. These holes are where the electronic components of the PCB including via holes are to be placed and interconnected. Holes are drilled with a diameter of approximately 100 to 150 microns. Precision is the key to the drilling process. Laser locator or X-Y coordinate systems are used to achieve precision.
Step 10: Copper Deposition and Platting
This step is to cover the entire panel with a fresh layer of copper after drilling. It bonds the panels and also covers the nonconductive materials opened up after drilling. A chemical electrolysis setup is used for plating. The drill holes are covered with around 25 microns of copper to ensure proper connection.
Step 11: Outer layer imaging and copper etching
Similar to step 3 a photoresist material is applied over the outer copper layer and then they are imaged. Tin guard covering is provided over the required copper area as a protection and the other unwanted copper is removed. PCB connections are established after this step.
Step 12: Solder Mask Application
The board is now cleaned and the solder mask is applied. Solder mask is to protect the board from copper oxidation, damage, and corrosion. An Expoxy is applied along with a solder mask which gives the usual green color to the board. Unwanted solder mask is removed by exposure to UV light. Then the board is oven-baked.
Step 13: Gold or Silver surface finish
The PCB is then plated with gold, silver or lead-free HASL or hot air solder leveling finish. This is done so that the components are able to be soldered to the pads created and to protect the copper.
Step14:Silkscreen
The silk-screening or profiling is the process of printing all of the critical information on the PCB, such as manufacturer id, company name component numbers, debugging points. This stands useful while service and repair.
Step 15: Electrical test
Electrical test is done using probe testers. Open and short circuit tests are performed. Electrical tests ensure functional reliability. Durability testing are also performed after functional test.
Step 16: V-Scoring
The actual PCB is cut out from the manufactured panel. PCB is cut out in specific sizes and shapes based upon the customer design and as per the original Gerber file date.
V-cuts are made along the sides of the board which permits the board to easily pop out from the panel.
Step 17: Final inspection and packing
PCB is subjected to final visual inspection and quality inspection. Test reports are provided for customer verification. Vacuum sealed or airbag/air pocket packaging is done to prevent any physical damage to the boards.
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