Untitled Quiz

Course Objectives

• The course provides skills for effectively designing and implementing printed circuit boards (PCBs).
• The course covers all aspects of PCB design from initial idea to final product, outlining the steps involved in design and fabrication.

Outline

• Introduction
• Introduction to PCBs
• PCB Fabrication Assembly
• PCB design Software tools
• PCB design: Practical examples + Projects for students

Introduction

• The printed circuit board (PCB) is a crucial component in electronic circuits and equipment.
• Building an electronic circuit with breadboards and zero boards is possible but less efficient and prone to damage compared with a PCB.
• PCB design involves a complex process of placing components.

Textbooks

• D. L. Jones, "PCB Design Tutorial", June 29th 2004
• M.I. Montrose, "Printed circuit board design techniques for EMC compliance (A handbook for designers)", IEEE Press series on electronics technology, 2000

What is PCB?

• A PCB mechanically supports and electronically connects electronic components.
• It uses conductive tracks, pads, and other etched copper features on a non-conductive substrate.
• PCBs transmit signals and power through electronic devices.
• They consist of one or more layers of conductors separated by insulating material.

Importance of PCB

• Saves time and energy.
• Serves as the foundation for many computer components.
• Reliable option.
• Reduces product size and cost.
• Provides physical structure for mounting and holding electronic components.
• Facilitates input/output connections for device functionality.
• Offers electromagnetic shielding to protect components from electromagnetic frequencies (EMF).

History of PCB

• The first printed circuit board concept dates back to the early 1900s.
• Charles Ducas patented an electrical path on an insulator surface in 1925, which revolutionized wiring and efficiency.
• Printed circuit boards became widely used after World War II thanks to Dr. Paul Eisler in Austria.
• Machine manufacturing of PCBs gained prominence in the late 20th century.
• Modern advancements include implementations in 5G, IoT, and AI.

PCB vs. Breadboard

• PCB: Stability, reliability, space efficiency, better grounding, permanent mounting,
• Breadboard: Flexible, easier debugging, faster assembly

PCB vs. Breadboard (System Considerations)

• Multiple engineering disciplines are involved in PCB design (Customer, Program Management, Systems Engineering, Software Engineering, Electrical Engineering, Mechanical Engineering, Component Engineering, Test Engineering, and Supply Chain)

PCB Types

• Single Layer: One layer of substrate with conductive traces on one side. Used in smaller electronics like calculators and cameras.
• Double Layer: Two layers of substrate with conductive traces on both sides, enabling more complex circuit connections. Used in industrial controls, power supplies, and more.
• Multilayer: Multiple layers of substrate interconnect various circuits making complex, high density designs possible. Essential for high-performance applications like data storage, satellite systems, medical equipment, and GPS technology.
• Rigid-Flex: Flexible combined with rigid construction offering flexibility and compact designs.

Parts of PCB

• Conductive Layers: Copper foil providing electrical connections between components ("traces").
• Insulating Layers: (Dielectric) Isolating conductive layers to prevent short circuits. Typically made of FR4.
• Components: Various electronic devices like transistors, resistors, integrated circuits, etc.
• Pads: Areas where components connect making electrical contact to the circuit.
• Traces: Copper tracks connecting pads for signal flow.
• Vias: Holes linking different layers for electrical connections between components.
• Silk-screen: Printed markings on the PCB surface for identifying components and other data.

PCB Characteristics

• Solder Mask: Insulating layer covering the PCB surface protecting the copper traces from oxidation, damage, or corrosion.
• Through Hole Mounting: Mounting components through holes in the board.
• Surface Mount Technology: Mounting components directly on the PCB surface. Requires modifications to component design for surface mounting.

Design Process

• PCB design is a complex process involving multiple disciplines, requiring constant bi-directional communication.
• It includes the design, manufacturing, and testing processes of the electronic circuit board. It blends electrical, mechanical, software, systems, testing and manufacturing aspects.

Step-by-Step PCB Design Guide

• Electrical parameters knowledge (current, voltage, signal types, etc.) is crucial at the start.
• Design involves multiple steps like schematic creation, layout designing, placing components, adding labels, and generating data files.

PCB Design Rules and Constraints

• Electrical Design Rules: Covers electrical properties like impedance and voltage.
• Physical Design Rules: Concerned about factors like trace width, via sizes, differential pairings.
• Spacing Design Rules: Specifies clearances between lines, pads, vias, and copper.
• Same Net Spacing Rules: Clearances between lines, pads, vias, and copper areas on the same network; separated from net-to-net rules.

Design Rules

• Proper trace spacing to avoid short circuits.
• Avoiding 90° angles in trace routes for better performance.
• Define and consider trace width based on current needs, component design considerations, and manufacturability.
• Define pad sizes based on the intended components.
• Identify various types of PCB pads (square, circular, island-shaped, oval, open-shaped).
• Maintaining spaces (3mm) around pads and between components.
• Define and maintain minimum pad sizes and distances.

Component Rules

• Maintain consistent orientation for similar components.
• Sufficient space between components to avoid heat damage and allow easy routing.
• Maintain proper distances from components to edges and between components.

Designing Multilayer Boards

• Multilayer PCBs have multiple layers, unlike double-sided boards. These have multiple layers of conductors and insulators.
• The stack-up usually includes copper, core, substrate, and prepreg layers fulfilling various functions.

Construction of Multilayer Boards

• Interconnecting methods like through vias, blind vias, and buried vias are employed for multilayer PCB construction.

Structure of Multilayer

• Lamination process bonds layers using high temperature and pressure with prepreg.
• Copper conducts electricity and performs various tasks like signal/ground planes.
• Multi-layered PCBs increase the routing space to allow complex circuit routing and provide space to handle high-speed signaling.

Power and Ground Layers in PCB Stack-up

• Power and ground planes enhance EMI reduction by efficient current flow paths.
• Power/ground pins of components directly connect to power/ground planes.
• Adjacent power planes to ground planes reduce EMI.

Advantages and Disadvantages

• Advantages: Smaller size, lighter weight, and higher durability.
• Disadvantages: Challenging to repair, more costly, more complex design, manufacturing, and testing process.

PCB Fabrication Steps

• Designing electronic circuits, layout printing, substrate preparation, etching, drilling, electroless copper deposition, solder mask application, assembly, testing and final inspections.

PCB Layout Design

• Design the PCB layout using software tools (KiCAD, Eagle, and Multisim).
• Defining trace widths based on manufacturability and current limitations.

PCB Layout Design (Other considerations)

• Access to critical nodes and component placement.
• Distance requirements are essential between components, vias, and component mounting holes.
• Proper component orientation.

Layout Printing

• Use of a plotter printer for printing the circuit details on film with distinct ink colors for conductive (black) and non-conductive (clear) areas.

Preparing Substrate

• Selection of materials for the PCB like fiberglass-reinforced epoxy resin (FR4) based on performance, reliability, cost, and thermal considerations.
• Ensure high mechanical and thermal stability.
• Copper clad laminate is required for electrical circuitry with both single and double sided options are possible.

Etching

• Physical removal and chemical etching processes to remove unwanted copper traces revealing desired traces, using materials like Ferric Chloride solution.

Preparing Drill Holes

• PCB drilling for creating holes, slots, or cavities on the PCB.
• Selection of through-hole, blind-hole, or buried-hole as needed.
• Manufacturing typically employs automated machines or laser drill methods.

Electroless Copper Deposition

• Chemical plating with copper to provide adequate conductive layer thickness.
• Precision-controlled thickness is usually 1 mil or similar.

Soldermask Application

• Applying solder mask covering non-circuitry areas to protect copper traces from damage, oxidation, and corrosion during assembly.

Assembly

• Assembling electronic components onto the PCB layers.
• Use of soldering techniques and materials like solder and flux.
• Implementing Surface Mount and Through-Hole assembly methods as needed.
• Components like terminals, resistors, switches, capacitors, networks, and transistors are placed.

PCB Assembly Process (Solder Paste Application)

• Applying solder paste using stencils to targeted areas on the PCB.

Pick and Place

• Using machine tools to place components onto pre-prepared solder paste areas in the correct locations on the PCB.
• Computer-vision based quality control during placement to avoid errors.

Reflow Soldering

• Applying heat to melt solder paste to create a permanent connection between the component and the PCB.
• Employing either convection or vapor-phase reflow soldering methods to accomplish the bonding.

Inspection and Quality Control

• The final step, involving inspecting PCBs for defects using automated or manual methods, and using quality control mechanisms to validate the final product.
• Checking PCBs for missing components, incorrect placements, and solder defects.

Silk Screening

• The process of creating markings for identification and other design details.
• Used to label and mark the locations of components.

PCB Testing

• Functional and electrical testing validating proper circuit operation, performance, and quality of the finished PCB.
• Methods like probe testers are employed.

Cutting Individual PCBs

• Severing and isolating individual PCBs from the production panel.
• Precise cutting is important without harm to neighboring PCBs during separation.

Final Inspection and Packaging

• A thorough inspection of individual PCBs for defects (like scratches).
• Ensuring all PCBs meet the relevant quality standards and specifications.
• Packaging to protect PCBs from environmental damage when shipping.

Multilayer PCB Manufacturing Process

• Design and Layout: Using software like Altium, Eagle, or KiCAD to design and create PCB layouts and stackups.
• Pre-production: Materials selection (copper foil, prepreg, core materials) and process selection for manufacturing.
• Inner Layers: Steps of drilling, plating, lamination, and etching to create multilayer PCB structures.
• Layer Lamination: Bonding individual layers to produce a solid multilayer panel.
• Outer Layers: Manufacturing of outer copper layers, bonding them to inner layers and creating the final multilayer PCB.
• Final Production: Cutting, routing, and performing tests (electrical) ensuring adherence to the proper quality standard for the customer.