Special Seminar I
Electronic Prototyping:
Methods, Tips, Tools, and Skills
Dr. Peter W. Pachowicz
Department of Electrical and Computer Engineering
Volgenau School of Engineering
 This seminar is dedicated to students taking senior design project or
attempting to take it very soon
 The focus is on practical aspects of engineering necessary to complete
senior design project successfully and professionally
Goals
 To learn practical technical aspects of engineering
prototyping
 To get advice before your full scale hands-on experience
 To avoid costly mistakes in implementing senior design
projects
 To use senior design lab resources properly and efficiently
 Other seminars: “PCB Design”, “SMT in Practice”
 Other materials: Refer to the ECE492/3 web site for instructions on PCB
design, 3D printing, Laser cutting, etc. --- all supported by the in-house lab
equipment and prototyping capabilities
 Get a hardcopy of a catalog from Jameco (or other electronic distributor)
and learn about hardware technology! There is a ton of information there.
Acknowledgement: Special thanks to Prof. Young for his help in preparation of selected slides.
Topics
 Design
 Breadboarding
 Components
 Vector-boarding
 Soldering
 Rework
 Wire-wrapping
 ESD Prevention
 Tools
 Supplies
Note: Please listen carefully and keep notes. There will be
a lot of information provided that is not on these slides.
Design Tips:
Don’t reinvent the wheel
 Use cookbooks to study example designs
 Circuit reference books
 There are many specialized books
 Review and understand ‘Application Notes’
 Manufactures want you to use their chips
 A lot of help is provided in these notes
 Frequently, application notes are issued as
separate pdf files
 Search the Internet
 But you need to be very careful
 There are many designs errors there
Design Tips:
Design steps
 Understand background functionality of components and
a circuit to be designed
 Consider a modular design approach (see next slide)
 Draw or sketch circuit schematics
 Use professional tools: OrCAD, KiCAD, etc.
 Be careful about other tools due to file export problems
 Think carefully about power supply requirements
 Simulate in P-Spice
 Have a Design Review with other team member(s)
 Create a Bill-Of-Materials
 Secure the parts (parts availability)
Modular Hardware Design
 The goal is to split a design into smaller interlocking
modules (think about Lego blocks)
 Particularly useful when your design is not proven
 Design change will mostly influence a single module
 No need to redo and repopulate the entire PCB again
 May save time and costs
 Think carefully about a system interface
More pins  More flexibility
 Have an extra board space
 Use hardware components for
board support
 At least support the ‘main’ module
Power
Analog
MCU
Actuator
ctrl
Poor Designs
 Blindly used sample designs
 Did not do a ‘real’ design review
 Did not simulate the circuit
 Did not even analyze the circuit
 Intuitively selected component values
 He just built it
 Trial-and-error approach
 Too narrow focus
 Did not consider other elements connected to the circuit
Work Smart, not Hard
Schematic
 Absolutely necessary in ECE492/3
 Use professional design package
 Plan ahead
 Learning schematic software can be time consuming
 You will need to create new components and/or footprints
 Consider modular design for a follow-up implementation
 Use hierarchical sheets
 The schematic must be complete enough that the
designer can give it to someone else on the team who
will implement it
 Simulate right away every time there is a chance
Prototyping Stages
Breadboarding --- Vectorboarding --- PCB
 Your primary goal is to
deliver a PCB (!!!)
 Consider other
implementations as
intermediate
 Always be a
professional
 Building hardware
takes a lot of time
and requires skills
 Integrating
hardware and
software is truly a
challenging task
Implementation Decisions
 Which prototyping method to start with ?
 Which one to use for a target system ?
 All depends on:
 Design skills
 Prototyping stage
 Prototyping skills
 Components and system type
 Experience
Remember: Never finish your senior design project
with a breadboard (!)
Breadboarding
 Purpose: To verify the circuit design and select final
component values
 First step in prototyping
 More experienced engineers may skip this stage
 Used only for very small circuits
 Work neatly! Take your time.
 Trim component leads and wires to lie flush or flat the
best you can
 Power and ground wires must be always flush (best if
color coded)
 Use no more than five ‘free flying’ jumper wires
 Treat them as temporary and replace by flush/flat ones asap
Good Breadboarding
What is
potentially
wrong
with this ?
Bad Breadboarding
How about This One?
Worst Breadboarding Award
What is This ?
Problems with Breadboarding
 Frequently exhibits an unstable behavior
 Bad connections
 Transportation problems
 Loose wires WILL touch other components
 High flexibility most likely will inhibit your thinking
 Connection and component changes are done to “check itout” rather than done after a thoughtful process
 Stop playing! Think what you do!
 SMT components require breakout boards
 Be careful when using higher frequencies (above 40MHz
or nano-sec timing)
Additional Breadboarding Tips
 Run DC lines and grounds first so they are buried under
the signal wires
 Use Red/Green for power, Black for ground
 Use many varied colors for signal wires to make them
easier to trace (get old multi-pair telephone cable)
 Never use clip leads!
 If it does not work, check wiring first
 As you make connections on the board, use a highlighter
to mark each section of the schematics as it gets wired up
 Group components into logical sections, if possible
 Use a constant voltage + constant current bench power
supply. Set current limit to minimize blowing up chips.
Critique this Breadboard
Critique this Breadboard
Breadboarding Cautions
No high voltage on a Breadboard!
 Way too dangerous.
 If you are working with AC power or high voltage DC, you
need to receive a permission to do it and an additional safety
training. In general, you will not receive such a permit!
 Vector board is more suitable in these cases. Also, cover the
high voltage areas and keep it separate from the low voltage
breadboard.
No high currents on a Breadboard! (above few amps)
 You may overheat the wires, connections, as well as get high
I2R losses
 Again, build and wire these on a vector board with heavy
gauge wire
Few Words about Components
 Be sensitive to quality !!!
 Learn about component technology
 E.g., Capacitors: electrolytic, ceramic, tantalum, radial,
disk, monolithic, mica, polyester film, metalized film, etc.
 Do not overlook power and voltage ratings
 Value tolerances can make or break your design
 Buy extras if price is relatively low
 Technology: DIP vs. SMT
 Consider other aspects
 May need to be soldered within 24-48 hours
 Check spec sheet and application notes for additional
requirements

For example – PIC24 requires a 10uF tantalum capacitor
Component Tips
 Don’t forget bypass capacitors!
 Use shielded cable if you are moving very low level
signals around and have very high gain amp.
 You can speed up your work if a chip has an Evaluation
Board – additional cost can save a lot of time and will
assure that you will get a working board to test
 But do not use the Evaluation Board on the target system !
 If the simulation was correct, the circuit should work as
expected. But until you build it, you will never know.
 More chips are available as SMDs. Use breakout boards!
THT technology is gradually phased out.
Vector (“Perf”) Boards
 Vector is a company that makes perforated boards
 Very useful when:
o You need a permanent circuit (vibration, transportation,
extensive testing, demoing, etc.)
o You work with higher voltage/current applications (so you
can isolate this circuitry and use heavy gauge wires)
o Your circuit has more components that can reasonably fit
on a breadboard
o Your are making a digital board with lots of bus
connections (using wire wrapping – see next slides)
o You need to use larger/special connectors
o Your system/approach involves modular design (so you
can connect individual boards or replace them by PCBs as
you progress through the implementation)
Vector/Perforated Boards
 There are different types of these boards
(no pads, single-/double-sided pads, w/
bus, etc.)
 Get one of better quality; one-sided w/
larger square pads
 Larger pads are easier when soldering and
do not come off the board easily
 Circular pads are not reliable enough
 Consider boards with busses
 They provide much better clarity of
connections you need to arrange
 They cost more but wiring is simplified
Most mistakes and significant time loss
are due to wrong connections (because
you work on the bottom layer)
Excellent Vector Board
Critique this Vector Board
Critique this Vector Board
Vector-Boarding Tips
 You can start with a BB and then move to a
vector board if no PCB is planned
 Be sure you have more space than you need
Use larger boards or go modular
 Use PCB board mounting hardware to keep your
board above the table surface
 Chip sockets are very useful (if they are of a
higher quality)
 Mark chip/component positions on the copper
side (bottom layer). Remove marks for demos.
 Use Teflon hook-up wires (solderable at higher
temperature)
 Consider wire wrapping
Breakout Adapter Boards
 SchmartBoard
 Large selection of SMT to DIP adapters
 PCB technology to make soldering easy
 Cover pitches down to 0.4mm
 Check for YouTube instructional videos
 Note: RoHS requires a bit higher iron temperature
 DigiKey
 AllElectonics
 50x80mm grid of SMT pads on 0.05” centers
Soldering Tips:
Beyond the Basics
 Temperature controlled station is the best
 Temperature setup
 Depends on the solder type
 Too low  “Cold solder effect”
 Too high  Critical metals evaporate
 Accelerated oxidation
 Solder/joint fracture
 Select proper tip size and keep it clean
 Use a flux pen (does not leave a mess)
 Clean your board after all elements are soldered
 Soap+water+brush; Isopropyl alcohol; Ultrasound
cleaner
Soldering Tips: Use Both Hands
 Most effective and time efficient
soldering is done using both hands
 Iron in one hand
 Solder wire in the second hand
 You need a third hand to hold your
board
 Hold your board in a vise
 You need a forth hand to hold your
components in place
 Use glue (with drying time ~5min)
 Apply only a small dot of glue (!!!)
 1-2-3-4 soldering rhythm:
1
2
3
4
IronWaitSolderRelease
Rework Tips
 Think ten times before removing components from
any board – it’s more difficult than soldering
 MEs say: “Measure ten times, cut once”
 First, use a solder-wick to remove solder
 A very inexpensive method
 Using solder suckers is really challenging
 Cutting pins off helps a lot
 Component will be lost
 Use a flush cutter with needle-type tips
 But, be careful, do not apply lifting pressure on
copper pads
 Remove pins with the help of an iron and fine point
stainless steel tweezers
Wire-Wrapping
 Good old technology for making many
connections (wiring backplanes in telecom equip)
 Use an inexpensive manual tool
 Match wire gauge to wrapping tool size!
 Use sockets and pins for wire wrapping
 They have longer pins
 Pin shape is square
 You can attach more than one wire to a
single pin
 Hold a socket in place by:
 Soldering one or two pins to pads, or
OK
 Gluing – using two dots of glue on
opposite sides
OK
ESD Prevention
Protect your work from static discharge !
 This is particularly important during
winter
 At minimum, wear a grounded anti-static
wrist strap
 Transport/store your work and
components in anti-static bags
 Use grounded anti-static mat or
aluminum sheet (lab) as your table top
 If your component does not work at all,
most likely it was damaged by: ESD,
overvoltage, or short-circuit
Tools
 Have a separate plastic box (not a backpack)
to transport and store your boards,
components, and tools
 Check: Home Depot, Harbor Fright
 Tools:
 Quality tweezers (non-magnetic)
 Small needle nose pliers
 Small wire cutters
 Small gauge wire strippers
 Screw driver set
 Small “crescent” wrench
 Digital mutimeter
 All hardware tools must be ESD graded
Electronics Suppliers
 First tier: Large professional companies
 DigiKey
 Mouser Electronics
 Newark Electronics
 Second tier: Value suppliers
 Jameco (get printed catalog)
 Third tier: Secondary/Surplus suppliers
 MPJA
 All Electronics
Local Electronics Store
RadioShack has limited parts and tools... But we are lucky…
We have an electronics store in Springfield, VA.
Additional Tips
 Technical Manager: put all printed documentation in a
3-ring binder, not a folder (pages get lost that way)
 Allocate a lot of time for implementation (on top of the
design stage) and stop ‘playing’ with hardware
 Rushing does not pay off. It can turn you back in time at
a critical moment.
• Always think about what can go wrong; Have a Plan B
• Test, test, test at every step
• Never try to integrate more than two modules at a single
step (applies to hardware and software)
• Keep it simple, stupid (!)
 Be highly organized and keep your workplace clean
 Attend other two seminars
Conclusions
There is no such thing as a short cut. Do it right!
Have a good schematic before you start building
Breadboard/Vector-board is used to verify the schematic
(a representation of the design) and component values
Build a circuit on a Vector-board to ensure reliable
operation during intermediate testing and demos
Once you have a verified schematic, you should output a
Netlist and begin your PCB board layout
Your goal should always be to finish your senior design
project with a PCB
Questions