1. CPE495 Computer Engineering Design I Emil Jovanov Electrical and Computer Engineering The University of Alabama in Huntsville Introduction to PCB Design

2. CPE495 Computer Engineering Design I, Dr. Emil Jovanov, UAH 2 Schematic Capture and PCB Design ExpressPCB schematic capture and PCB Design  http://www.expresspcb.com/ExpressPCB software http://www.expresspcb.com/ Component selection  Through hole  SMT Design for Test  Test points, grounds, etc.  Spare components

3. CPE495 Computer Engineering Design I, Dr. Emil Jovanov, UAH 3 ExpressSCH ExpressPCB schematic capture  Quick Start Guide  examples New Schematic Component Manager Custom Components Wiring  Standard NET lists  ExpressPCB integrated support Sheets and Ports Checking for Errors

4. CPE495 Computer Engineering Design I, Dr. Emil Jovanov, UAH 4 ExpressPCB ExpressPCB PCB design  Quick Start Guide  examples Layers Traces  Linking the Schematic and PCB Grid Rules for Component Placement Ground plane Component Manager Custom components Ordering boards

5. CPE495 Computer Engineering Design I, Dr. Emil Jovanov, UAH 5 PCB Design Component floor plan Placing components on one side only / both sides  Snap-to-grid  Turn-off for unusual pin spacing  Components that need to be in specific locations  Daughter board  Minimize trace lengths  Component orientation  Polarized part orientation  Mark the positive leads / pin#1 (silk or text on the layer)  Leave enough room for traces in the beginning Test points and design for test Print out a copy of the layout and check the design with real parts

6. CPE495 Computer Engineering Design I, Dr. Emil Jovanov, UAH 6 PCB Design – Power and Ground(s) Wide traces to common rails  0.05” - 0.1” (GND) if possible  Suggested: Power rail along the front edge, Ground along the rear edge of the board Ground(s)  Analog and digital ground  Design issues System separation  Ground problems  Optical isolation  Double diode  Examples

7. CPE495 Computer Engineering Design I, Dr. Emil Jovanov, UAH 7 PCB Design – Signals Wide traces for higher current signals  0.01” – 300 mA  Good for low current digital and analog signals  0.05” – 2 A  0.1” – 4 A Make at least 10 mils spacing  Larger voltages – larger gaps Vias (plated-through hole) Vertical traces on one side, horizontal on the other  Directions: vertical, horizontal, 45   Avoid sharp, right angle turns (use two bends) Place text to determine what is the top layer  Project, author,etc.

8. CPE495 Computer Engineering Design I, Dr. Emil Jovanov, UAH 8 Analog Ground Example Analog Ground

9. CPE495 Computer Engineering Design I, Dr. Emil Jovanov, UAH 9 WISE 2.1 Example

10. CPE495 Computer Engineering Design I, Dr. Emil Jovanov, UAH 10 Custom components Custom components in SCH and PCB Libraries  Sharing the same libraries  Team work

11. CPE495 Computer Engineering Design I, Dr. Emil Jovanov, UAH 11 Verification Print and check component layout Double check the routing of every signal  Use highlighter Check for missing vias  Print separate layers  check for traces with dead-ends (not connected)  Check for traces that cross each other Check for metal components (heat sinks, crystals, etc.) that can cause shorts Ordering boards