Life is a learning excursion, and the more questions you ask, the
richer your journey.
One of the things I have learned after twenty years of design work is
that questioning is an art. Whatever situation you find yourself in,
you will eventually be given instructions that seem contrary to what
you have learned. Should you follow the instructions without question?
Knowing when you don’t know enough and then knowing the right
questions to ask that will allow you to perform the task at hand is
germane to the art of questioning.
I remember starting a new job designing cell phone amplifiers, and the
pre-amp was a 1.67 GHz circuit on a Teflon board. The circuit was
entirely on Layer 1, and Layer 2 was a back side ground plane. When I
showed the engineer my preliminary layout, he instructed me to move the
components so close to the main signal line that the component pads
were sitting directly on top of the wide trace. Well, this just
didn’t seem right to me.
So, I proceeded to tell him how we frown on this practice, because the
pads would have no thermal relief, and without solder mask on this
design we wouldn’t even have the advantage of having solder
mask defined pads. I was quite proud of myself for pointing this out,
having just recently learned about these things from a seminar. With
great patience he explained how he was very aware of good soldering
practices, but had technical concerns that far outweighed the
well-meaning guidelines I was quoting. I was slightly embarrassed, but
learned an important lesson. In certain cases engineers will
consciously break rules and bend guidelines to get the results they
need.
We’ve all heard the term, “Rules of
Thumb.” A rule of thumb isn’t really a rule,
it’s more like a guideline that is easy to remember. But what
happens if people learn the rule and repeat it to others who in turn
pass it on to others? Eventually, no one has an idea of where it came
from or the real purpose that was intended. If we are making decisions
without understanding the foundation the rule was built upon then we
don’t know what the decision means, or under what
circumstances it should be changed. The value of a rule of thumb is
that it makes it easier to remember something, but to be a good
designer you have to know what is behind the rule so that you know when
it needs modification. The best designers will know when the rule of
thumb should be abandoned or modified to get better results.
When you hear something that conflicts with your own understanding of
good design practices, first try to determine if the difference is
important enough to question. If so, try to determine if the person
providing the conflicting rule is merely repeating something without
understanding the basis for it, or if it is someone who truly has a
deeper understanding and is making a conscious decision to veer away
from the guideline. Not that it matters who is "right," but if it helps
you to initiate a discussion it may result in a better product and in
gaining valuable knowledge for future designs.
It’s important to make a distinction between guidelines and
rules. Guidelines provide a place to start in the absence of any other
factors – a foundation to build on. Rules are often legal
requirements and should not be ignored. For example, UL may require a
certain distance between high-voltage conductors. This rule is probably
not negotiable. If someone is asking you to bend a rule that will
affect safety or could cause legal trouble, you are obligated to
question it.
Sometimes it is helpful to be able to ask questions outside of your
organization. I have three suggestions for appropriate public venues
for questions. First, find out if the software you are using supports a
User Group. If so, you can present your situation to a focused group of
people who will be more familiar to your situation because they are
using a similar tool. Secondly, the IPC supports a number of free
email-based forums (sometimes called “listservers”)
for many different areas of our industry. To find out more about them
you can go to www.ipc.org and look under the
“Knowledge” tab. Finally, attend conferences like
PCB East,
PCB West and others sponsored by IEEE, IPC and other industry
organizations. In any of these you will find knowledgeable people
willing to help.
When you are using a public forum like a web-based user group or an IPC
listserver, here’s some advice. Try to find out what has
already been written about it before you ask your question, and be
specific in how you ask the question. If you ask a general question,
people may wonder if you’re just writing a term paper or
trying to get others to do your work for you. On the other hand,
something like, “I searched the archives for this subject,
and found a post I don’t understand," or
“I’m being told this from one source, and another
source seems to contradict it," you will probably get a better
response.
Ask questions! We all have a natural desire to appear competent, and
admitting that you don’t understand something may seem
contrary to building other’s confidence in you, but people
respect someone who has the courage to say “I’m not
sure about that subject, but I’m willing to research it and
get back to you as soon as possible.” None of us was born
knowing everything.
In the world of design, the technology is advancing so
quickly that even if you knew everything it would still be
hard to keep up. Remember, we are all somewhere along a lifelong
learning curve and none of us should be afraid to ask questions along
the way. The more questions you ask, the more opportunities you will
have to learn new things and get a better understanding of another
person’s point of view. Ask on!
PCD&F
Jack Olson
is a guest columnist this month on Tip Jar. Olson is a
circuit board designer for Caterpillar, Inc. and can be reached at
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