Pre Layout Design Review
Before design activity can begin, the
'ground work' must be laid to establish the
form, fit and function of any printed
circuit board. Successful PCB design happens
when Marketing, Program Management,
Engineering, Manufacturing or Production
Control, Test and Integration, Material
Control and Quality Assurance work in
concert toward a design that functions as
the customer requires, with a reasonable
performance margin, for a reliable product
life cycle that the customer needs..., and
for the price that the customer will pay and
a profit margin that makes the company
healthy and successful.
An overall approach is needed to support the
entire program, not just the needs of any
one department or small group of
individuals. Having a board work in the
Engineering Lab is not proof of a
manufacturable product, it is only proof of
concept... not designed to the rules
required to make a reliable, manufacturable,
testable, and deliverable product.
Before layout, the team members from
Planning, Engineering, Manufacturing,
Material Control, QA, and Test need to be
consulted and given a opportunity to review
the 'potential product' to give their
valuable input as early in the design
process as is practical to make sure that
all disciplines are informed and their
design considerations are evaluated and
planned for, in the initial stages of the
design. This does not mean that an engineer
can't prototype his or her circuit before
these meetings, but the meetings are
essential if you are to produce the product
in a cost effective manner.
The PCB Designer must be prepared by knowing
the needs of the different departments
involved and being sensitive to those needs
in developing the printed circuit design.
The following are examples of questions that
could be asked by the PCB designer at the
Pre-Layout design review meeting.
To be discussed :
When do we need the design done (how about a
What is our cost target for the PCB?
How many units do we expect to ship per
year? per month? per quarter?
How are we going to test the PCB? In-house?
What are the customer requirements? (this
will be Marketing's info)
What is the expected life of the product?
What Logic families are we dealing with?
What frequencies will we be dealing with?
What limitations do we have electrically?
What limitations do we have mechanically?
What limitations do we have environmentally?
Are there any high current devices to be
If so, what currents and voltages?
What sort of thermal challenges will the
How will the board be mounted?
What sort of connectors will be needed?
What sort of user interfaces (panels,
switches) will there be?
What sort of indicators or displays will be
What agency approvals will be required?
What are the physical constraints for the
What bus structures will be employed?
Do we need impedance matching?
Will we need stripline, micro-strip or
special RF or Microwave technologies?
What material(s) do we wish to use?
Will the board(s) be solder coated?
How will the boards be assembled?
Will the boards be through hole? Surface
Do we have library parts for all the
Do we need data sheets for specific
components to build those parts in the
Etc., etc, etc...
A proper review of the design parameters
prior to beginning work on the PCB is
paramount. If you don't have the review, you
will most likely be doing the board over
Customer Specifications Marketing
Requirements and Cost Targets
YOU as the PCB Designer need to know what
your marketing people already know from
interfacing with your customer... What does
your customer really want..., what will they
pay for it and when do they want it
delivered? With few exceptions, designs are
really built for a customer... whether it's
one company or an entire global consumer
based market. The customer has a specific
need, which you and your company hope to
satisfy... in exchange for dollars. This
makes your customer happy, and keeps you and
your fellow employees gainfully employed...
of course...- The American Dream... sucesss.
Here are a few givens:
If you design something that your customer
does not want... your customer will not pay
for it... your company looses money, you
need a new job...
If you design what your customer wants...
but it costs too much or your purchasing
department can't purchase the parts because
of long lead times or obsolete parts...,
your customer will not pay for it... your
company looses money, you need a new job...
If you design what your customer wants, but
your manufacturing people can't build
it....your company will not ship it, your
customer will not pay for it... your company
looses money, you need a new job...
If you design what your customer wants, and
your manufacturing people can build
it....but your testing department can't test
it....your company will not ship it.., your
customer will not pay for it... your company
looses money.., you need a new job...
I think by now you get the picture...
Ask your Product Manager, or Electronics
Engineer to discuss the PCB design intent
and end use of your product, from the
Marketing Proposal, before beginning your
layout. Find out what sort of environment
your board will need to survive in.
Will it be expected to work at altitude,
under vibration, at extreme temperature
and/or humidity? Will it need to work at
very High frequencies? or High Currents? or
low leakage? What about EMI or Radiated
Electromagnetic Interference..., are there
sensitive amplifiers that need shielding? or
mixed signal issues? Just putting components
on a PCB and hooking them up does not
necessarily guarantee that your board will
be a success. You need to apply the right
combination of features to take advantage of
all the tools at your disposal to succeed.
By the time the Electronics Engineer is
ready to give you a schematic diagram and a
parts list he/she should already have
thought about these issues..... (but don't
count on it...) If you prompt him/her with
the appropriate questions they usually will
get the answers for you, which will help to
make your design a successful one.