Download - PCB design and Introduction to KiCad
PCB design and Introduction to KiCadELEC-D0301 Protopaja15.6.2020Juha Biström
Why to make a PCB
● Mounting for components
● Wires between components
● PCB CAD will ensure the circuit is connected properly
● Hugely improved reliability, especially compared to some sketchy ratsnest of wires or breadboard
● Clean and representable solution to a product
3
KiCad
● Open source PCB CAD
– Main supporter Cern
● Efficient and versatile tool for design of circuits and PCBs
5
Components of KiCad
● Eeschema – circuit design
● Symbol editor – create and edit own symbols
● Pcbnew – Layout design based on circuit
● Footprint editor – create own footprints
● Gerber viewer – view manufacturing files
● PCB calculator – relevant calculators to help PCB design
– e.g. minimum trace width for specified current
6
KiCad workflow
● Create schematic/circuit– Create own symbols if needed
● Annotate symbols (components)
● Assign footprints to symbols– Create own footprints if needed
● Design layout based on previous steps– Previous steps can be visited if needed
● Generation of manufacturing files
7
General hints for KiCad
● Memorize at least the most common key shortcuts– It will speed up your work a lot
● Grab (g) ↔ Move (m)
● Absolute and relative (to a movable origin) coordinates– Can be used e.g. to aligning to a grid or measuring distances
– Origin is placed by space bar
● Internet has a lot of instructions and other material– http://docs.kicad-pcb.org/5.1.2/en/getting_started_in_kicad/getting_started_in_kicad.html
8
Tips to schematic design● Start by filling project information and adding mounting holes
● Use supply voltage nets (power nets)
● Create own nets where appropriate (label)– Multiple long wires make schematic unclear and disorganized
● Remember to add Power flags to power supply lines
● When schematic is done, proceed with toolbar special functions from left to right
9
Eeschema user interface
10
Eeschema user interface
11
Symbol annotation
● It's convenient and easy to annotate all symbols automatically at once
● Different naming conventions depending on e.g. project size
– Symbol number for whole project
– Sheet number * 100 + symbol number
– Sheet number * 1000 + symbol number
● Can be used to annotate a sheet at a time or whole project at once
● Can not be undone
12
Electrical rules check, ERC
● Checks circuit integrity based on pin definitions– e.g. two outputs shall not be connected together, supply voltage has to be present
● Problems might arise from errors in symbols– Especially in self made symbols
● Mystic power supply problems are usually due to missing power flags in external supply connection
13
Footprint association
● In this phase casing type and size will be chosen to symbols
● Can be changed later if e.g. PCB space is running out or component can't be found in that casing
● Self made footprints have to be ready before associating them
14
Tips to layout design● Start by filling project information and design rules
– E.g. minimum trace widths and spacings, trace widths to be used, via sizes
– Is the PCB going to be etched or produced commercially (→ check supplier minimum rules)
● Draw (preliminary) board edges (Edge.Cuts) and place mounting holes
● Spread components in groups e.g. by functional blocks
● Place critical parts and their traces then others– Connectors are convenient at board edges
– Indicators, connectors, check points and debug ports should be located on same side of board
– Switches, potentiometers, displays and other mounted to housing can be wired
– If etching board, try to avoid vias, as they are labour intensive to mount
16
Pcbnew user interface
17
Pcbnew user interface
18
Questions?
● Time for demo
20