PCB Design Basic Rules
PCB Design Basic Rules
The PCB architecture of the printed circuit board is one of the most significant design elements in the design of the electronics device. In most cases, the electronic hardware design engineer will design the circuit and then the PCB layout expert will render the PCB layout and configuration based on the schematic given by the PCB CAD system.
What comes before designing a PCB?
- Product designing: Share your ideas with the investors.
- First comes the idea.
- Investors can be engineers, meaning they can be educated and can have knowledge.
- PRD (Product Required Document): Consider products, specs finalization, meeting with the customers, major component selection by discussing with the CAM team, FAB house, software guys and stakeholders.
- Your design should be flexible and should have the tendency to change.
Ordering of the Components
- Lead time of components: how much time will it take for the component to be delivered.
- LLT (Long Lead Time) parts mean they will take more time to be delivered.
- So, you should be very alert and careful while placing the order and decide the crucial time to place the order.
- AVL: Approved Vendor List.
- When selecting a component also give names of 2 alternate components in case the first one gets out of stock at the time of ordering.
Datasheet Details
- It shows you different packages available for the IC.
- Shows electrical characteristics of that IC.
- Shows number of pins, pin name and numbering of the pins.
- Shows mechanical dimensions of the IC.
Designing Tools for Schematic
- ORCAD (Cadence)
- ViewDraw (Mentor graphics)
- Altium Designer
Library Development
- Creating symbols of components for our library development.
- Homogeneous part: Parts on a single place/sheet
- Heterogeneous part: Different symbols of a single component. For example: Xilinx FPGA.
Bill of Materials (BOM)
- After the schematic is completed, we export the net list and BOM.
- It is an excel file which shows item numbers, different components used, quantity of that symbols used, description of components, manufacturer name, part number
Attributes of Symbols
Symbol should have these attributes when creating schematic diagram:
- Manufacturer name
- Part Number
- Description
- DNP/DNI (Do not populate or insert)
- Wattage/Power
- Voltage
- Tolerance
- PCB Footprint
- Value of the component
Difference between Drafter and Designer
Drafter means designing schematic without using any knowledge or studying about the components to be used, while designer is a person who reads datasheets of the components and makes complete diagrams using some formulas also.
PCB Design Standards
One of the most widely used industry standards in the manufacturing of printed circuit boards is IPC-A-610. IPC-A-630—Acceptability Standard for Manufacture, Inspection and Testing of Electronic Enclosures.
Today, boards are made to be larger and smaller than this standard, but the standard probably remains the most common thickness for designs. Today, it is more accurate to say there is a range of common or standard PCB thicknesses. These include 0.031in (0.78mm ), 0.062in (1.57mm) and 0.093in (2.36mm).