Prototyping a Senior Design Project
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Transcript Prototyping a Senior Design Project
Printed Circuit Board Design
Sung Yeul Park
Dept. of Electrical and Computer Eng
University of Connecticut
September 24, 2014
What can you see from an electrical
engineering perspective?
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Three Elements to be considered
Components :
- How to select components?
- What values are needed?
- What kind of package will be?
Printed Circuit Board :
- Schematic Design
- PCB Layout Design
- Prototype board
Case or Box for the prototype board :
- Purchase or build by yourself
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Printed Circuit Board ?
A printed circuit board (PCB) mechanically supports and electrically
connects electronic components using conductive tracks, pads and
other features etched from copper sheets laminated onto a nonconductive substrate.
PCBs can be single sided (one copper layer),double sided (two
copper layers) or multi-layer.
Conductors on different layers are connected with plated-through
holes called vias.
Advanced PCBs may contain components - capacitors, resistors or
active devices - embedded in the substrate.
Printed Circuit Board Design
A PCB as a design on a computer (left) and realized as a board assembly
populated with components (right). The board is double sided, with through-hole
plating, green solder resist and a white legend. Both surface mount and
through-hole components have been used.
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Printed Circuit Board Design
Schematic Design
PCB Layout
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Key terms for PCB design
Pads are where the components are soldered
to the PCB.
Traces are the copper tracks that
connect pads together.
Via are small holes through the board
that link a bottom and top trace
together electrically. Traces on the
same layer cannot cross, so often,
when you are laying out a PCB, you
need to a signal to jump from one
layer to another.
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Key terms for PCB design
Silk-screen refers to any lettering that
will appear on the final board.
Solder-mask is a layer of insulating
lacquer that covers both sides of the
board except where there are pads.
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Multi-layer PCB design
2 Layer PCB design: Top layer and bottom layer
4 Layer PCB design: Top, Bottom, and two middle layers.
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PCB design procedure
Design specification
Circuit diagram
Schematic design Select components
Check the dimension Build a footprint
Make a PCB library Add parts
Export schematic design to layout design
Route all connection
Design rule check
Generate Gerber files and drill file and zip them
Upload zip file to PCB order
website
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PCB Library design
Are you Ready to build a library?
Component datasheet
Dimension: mil (imperial unit) vs mm (metric)
1 inch =1000 mil, 1 mil = 0.0254 mm
1 mm = 39.3700787 mil
DIP component and connector: 100 mil or 2.54 mm
Symbol in schematic vs Exact dimension in Layout
Pad number should be matched in schematic symbol
and layout footprint
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PCB Library dimension example
Male header
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PCB manufacturing procedure
http://www.pa-international.com/images/stories/Multilayer%20Metal%20Plate%20PCB%20Process%20Flow%20Chart.JPG
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Tips for PCB design
Keep traces straight,
Try to avoid 90o turns use two 45o’s.
Double, even triple check layout,
Having a fresh pair of eyes look it over,
“measure twice, cut once” idea.
Trace thickness & spacing
Spacing of at least .010”,
0.030” for In-house
~0.025” per 1 Amp carrying lines,
Don’t use anything smaller than 0.010” for traces,
0.030” for In-house milling.
Try to keep all connections
on one side of PCB
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Take into account component package
Free PCB design program
EAGLE PCB Design Software:
http://www.cadsoftusa.com/download-eagle/freeware/
Express PCB:
http://www.expresspcb.com/expresspcbhtm/download.htm
Free PCB:
http://www.freepcb.com/
Advanced Circuits:
http://www.4pcb.com/free-pcb-layout-software/
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Making PCBs
Layout your circuit / circuits
Check out http://www.expressPCB.com for some
great tips on component layout and power
distribution.
Layout is more of an art.
Tight spaces
Lots of connections
Make a 2 level board into a 3 level with vias
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PCB Design Example
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Top and Bottom Layer
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Middle Layers(2nd & 3rd)
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DSP Board
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DC-AC Inverter
DC-DC Converter
PCB Design Assignment
Every senior design team need to design one printed circuit board
during fall semester.
The number of components should be more than 10 components
with connectors, surface mount components, through-hole
components, and ICs.
The number of layers should be 2 or more.
Report due date is November 19th 2014
Report: Schematic, Layout, and Free dfm Check result
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https://www.my4pcb.com/net35/FreeDFMNet/FreeDFMHome.aspx