PCB fabrication

advertisement
Produce Your Own PCB Board
Jack Ou
Engineering Science
Sonoma State University
Four-Bit Adder-Subtractor
(4 bit ripple adder)
A Four-Bit Adder/Subtractor on
Breadboard
Problem: too many wires!
Add Components
AND
Schematic
Tips
• Double click to terminate a wire
Add Junction to the Schematic
Add junction to the schematic.
Add Power and Gnd of Each IC
Chip to the schematic
1. Right click on a part
(74LS08N in this example)
2. Click on Invoke
Invoke a Part
Select PWRN,
Press OK.
Power and Ground Added
Move
• Use the Move button to alter any
component’s location
Click on + to move a
part
Delete
Display Net Name
1. Enter a net name
2. Display the netname
ERC error
Use ERC to check connectivity of the wire.
Rewire to Clear ERC Error
To Start a New Board File
Board Editor
If you keep both windows open, changes made on the schematic window
will be reflected in the layout window.
Turn on the Grid
Rearrange the Comopnents
(Right-Click to rotate a component)
(The smaller the board, the more economical)
Click on Route to Start Wiring Up
the Circuit
(Left click to select
air wire to route)
Double click
To remove wire
Routing Menu
Add angel to the wiring
(Two Metal Layers)
(Width of a wire)
You should select the width of the wire to be 0.04 inches (40 mils) or greater.
Reduce the Active Area
Hieight is 2.5 inches
Load the Design Rules
Minimum Width of 40 miles
Change Clearance Distance
Outer Via Dimensions
Alternative: Load the default
autorouter file
Auto Router
Click this option
to start autoroute
Result of Auto Route
2 metal layers used
Not area efficient
Use only the top metal layer for
layout
Header Termination
Terminate the traces going to the
header at the bottom metal layer
Reason: this is where the IC will be
soldered.
Header terminates at the top metal layer—not a good practice
How to Change Metal Layer
Step 1: Click on ripup, double click a
wire to delete.
How to Change Metal Layer
Step 2: Move the wires to create sapce
How to Change Metal Layer
Step 3: Route wire. Start routing at the top metal level.
Step 4: Click once to place the wire in an empty area.
Step 5: Switch to the bottom layer
Step 6: Make contact with the pad at the bottom layer
Change the Shape of Via to
Round
Round Via
Magnified View
A Sample Eagle Layout
Clean up
the metal
layer
Jumpers
• You will need to use physical wires as
jumpers in places where you can’t
route across existing copper trace.
Add Vias
• Add Vias
– Drill 0.03149 (Assumptions: 1. drill bit is
approximately 31 mils in diameter 2. wire
size is 29 mils)
– Diameter 0.056 (56 mils)
Provide Connection Via Jumper
(Right click to bend the wire by 45 degrees)
A Sample Layout
Display only the necessary Metal
Layers
Print Only Necessary Metal
Layers
(Show Bottom trace, pads, and via)
Display top layer
problem
Print Top Layer
Print the Bottom Layer
Print the Layout to a
Transparency
Run the transparency through
the laser printer twice to
produce better transfer
Practice with regular
paper before you use transparency.
Look at your layout on paper
and see if it will work at all.
Final Printout
Cut the Transparency
PCB Development
• With contribution from Kevin Zack
Cut the PCB Board
Please clean up after you are done!
Smooth out the rough edge with
Dremel
Clean the PCB with a scotch
pad or fine sandpaper
When the board is shiny, use
acetone to remove any oil or
grease on the board
General Procedure Transfer
Image
1. Run the transparency through the laser
printer twice to produce better transfer.
2. Tape the printed transparency on to the
a cleaned PCB board.
3. Heat a hobby iron. With light pressure,
iron the transparency onto the copper.
4. After the board has cooled, peel off the
transparency.
5. Use Sharpie to complete image transfer
Details Instruction for Double
Sided PCB
• Line up the bottom layer with the top
layer (with the ink side facing the PCB)
Details Instruction for Double
Sided PCB
• Make sure it can go on the PCB
Details Instruction for Double
Sided PCB
• Slide in the PCB (Kevin Zack)
Details Instruction for Double
Sided PCB
• Tape the transparency to PCB
Tape the printed transparency
on to the a cleaned PCB board
(Single Sided PCB)
Heat a hobby iron. With light
pressure, iron the transparency
onto the copper
Use highest
Setting-- 3
You can also try the laminator
After the board has cooled,
peel off the transparency.
Failed Image Transfer
Use Sharpie to Repair PCB Board
Precaution
• Etching Solution may leave stain on
skin and utensils. The use of rubber
gloves is recommended.
• Avoid prolonged or repeated
breathing of vapor or contact with
skin.
Develop PCB
1. Ferric Chloride is used to remove the copper
not protected by the toner.
2. Place the printed board into a container with
a lid and pour about ¼” of the acid solution
over the board.
3. Secure the lid and using a swirling motion,
agitate the solution for 15 minutes to 30
minutes until the unwanted copper is
removed.
4. After the excess copper is removed, pour
water over the board to halt the etching
process.
5. Dispose the left over chemical properly.
(Include the chemical rinsed off with water)
Ferric Chloride
container with a lid and pour
about ¼” of the acid solution
over the board
Agitate the solution
You can also try the orbital
shaker
Dispose Chemical Properly
Post Processing
• Clean off the toner protecting the
traces with a scotch pad or
sandpaper.
• Clean off any residue with acetone.
• Drill the board with a drill press. (Use 31
mil drill bit)
Remove Ink
(Before)
(After)
Drill Holes
Misc Slides
Download
Related flashcards
Create Flashcards