Design Mistakes You Must Avoid on Your New Electronic Product
Summary
TLDRIn this informative video, John Teal of Predictable Designs identifies 10 common mistakes in electronic hardware development, covering both technical and general design issues. He emphasizes the importance of designing for manufacturability, correct wireless circuit design, early cost estimation, and independent design reviews. Teal also addresses specific technical pitfalls such as improper PCB trace width, decoupling capacitor placement, and enclosure manufacturability. His insights aim to help engineers avoid costly errors and streamline the product development process.
Takeaways
- π οΈ Design for Manufacturability (DFM) is crucial as it can significantly impact the time and cost of bringing a product to market, and should be considered from the early stages of product design.
- π‘ Proper PCB layout for wireless circuits is critical for maximum power transfer. Impedance matching with a 50-ohm transmission line and LC matching circuit is necessary for optimal performance.
- π° Estimating manufacturing costs early can prevent costly redesigns later. It's possible to make accurate cost estimates before the final product design is complete.
- π Ensuring sufficient width for high current PCB traces is important to avoid overheating and to safely carry the required current.
- π Getting an independent design review can help catch and correct potential mistakes before they become costly in terms of time and money.
- β‘ Decoupling capacitors should be placed as close as possible to the component pins requiring stable voltage to ensure clean and stable power supply.
- π¦ Product enclosures must be designed with manufacturability in mind, considering the limitations and requirements of production methods like high-pressure injection molding.
- π Careful design of PCB landing patterns is necessary, especially when components are not included in standard libraries, to ensure compatibility with actual components.
- π Understanding the use of different types of PCB vias (through, blind, and buried) and their impact on manufacturability and cost is essential for efficient PCB design.
- βοΈ Correct PCB layout for switching regulators is vital for their efficient operation, and following the layout guidelines provided in data sheets can prevent common mistakes.
- π The video emphasizes the importance of avoiding common design mistakes to streamline the development process and ensure the success of new electronic hardware products.
Q & A
What are the common design mistakes discussed in the video?
-The video discusses 10 common design mistakes, including failing to design for manufacturing, incorrect design of wireless circuits, waiting too long to estimate manufacturing costs, insufficient width for high current PCB traces, not getting an independent design review, incorrect use of decoupling capacitors, designing the enclosure for manufacturability issues, incorrect PCB landing patterns, designing a PCB with manufacturing or cost issues related to vias, and incorrect PCB layout of switching regulators.
Why is it important to consider manufacturability during the product design process?
-Considering manufacturability is essential because it can significantly affect the time and cost of bringing a product to market. A product that is difficult to manufacture can slow down production and increase costs, which can be detrimental to the product's success.
What is the significance of a transmission line in wireless circuit design?
-A transmission line is crucial for the maximum power transfer between a transceiver and an antenna. It must be designed with the correct impedance to ensure efficient power transfer and optimal wireless functionality.
Why is it a mistake to wait until the final prototype to estimate manufacturing costs?
-Waiting until the final prototype to estimate manufacturing costs can lead to unexpected expenses and redesigns, which can delay product development and increase costs. Estimating costs early allows for adjustments in the design to manage expenses more effectively.
What factors affect the width required for a high current PCB trace?
-The required width of a PCB trace for high current is affected by factors such as the trace's thickness (copper weight), whether the trace is on an internal or external layer, and the permissible temperature rise for that trace.
Why is an independent design review important before prototyping a product?
-An independent design review is important to identify and correct potential mistakes or oversights in the design. It can reduce the number of prototype iterations, save costs, and shorten the time to market.
How should decoupling capacitors be used in PCB design for optimal performance?
-Decoupling capacitors should be placed as close as possible to the pin requiring a stable voltage source. The output capacitor for the power supply regulator should also be placed close to the regulator's output pin to ensure a clean and stable voltage supply.
What are the challenges associated with designing a product enclosure for high volume production?
-High volume production, typically using high-pressure injection molding, requires adherence to strict design rules. Unlike 3D printing, which is forgiving, injection molding does not accommodate complex or intricate designs without significant modifications.
Why is it a mistake to manually draw PCB landing patterns without verifying against actual components?
-Manually drawing PCB landing patterns without verification can lead to errors in pin-to-pin spacing, which can make it impossible to solder parts onto the board. It's essential to verify the landing patterns against actual components to ensure a proper fit.
What are the implications of using through vias, blind vias, and buried vias in PCB design?
-Through vias connect all layers of a PCB, which can increase board size and reduce routing space. Blind and buried vias, while allowing for more compact designs, have strict layer connection rules and can significantly increase the cost of prototype boards. They should be used judiciously and only when necessary.
What are the key considerations for correctly laying out a switching regulator on a PCB?
-For a switching regulator, the PCB layout must follow strict design rules to ensure efficiency and proper operation. Components should not be randomly placed but arranged according to the manufacturer's recommendations, which are typically provided in the data sheet.
Outlines
π οΈ Design for Manufacturability (DFM)
John Teal, founder of Predictable Designs, introduces the concept of Design for Manufacturability (DFM), emphasizing its importance in the development of electronic hardware products. He discusses the common mistake of underestimating manufacturing complexity and cost, which can be as significant as the product development itself. The video aims to educate viewers on avoiding this and other design pitfalls, regardless of their technical expertise. DFM is crucial for reducing time to market and ensuring efficient production, contrasting the outdated approach where engineers developed products without considering manufacturing feasibility.
πΆ Wireless Circuit Design and Testability
The second paragraph delves into the intricacies of wireless circuit design, particularly the critical nature of proper PCB layout for RF components. John highlights the importance of impedance matching for maximum power transfer between the transceiver and the antenna, requiring a 50-ohm transmission line and often an LC matching circuit. He warns against the common error of improper design, which can reduce wireless functionality range. Additionally, he touches on the concept of Design for Testability (DFT), which involves creating products that can be easily tested during production, as a subset of DFM.
π° Estimating Manufacturing Costs Early
In the third paragraph, John addresses the mistake of waiting too long to estimate manufacturing costs, which can lead to financial surprises and potential redesigns that delay product development. He argues against the misconception that accurate cost estimation must wait until the final prototype, asserting that with experience, costs can be estimated early in the design process. This proactive approach helps in making informed decisions about product development and can prevent costly iterations later on.
π High Current PCB Traces and Design Reviews
This paragraph focuses on the technical aspect of ensuring sufficient width for high current PCB traces, which is critical for components drawing more than 500 milliamps. John explains how trace width depends on factors like copper weight and layer positioning, with external layers being more capable of handling current due to better heat dissipation. He also stresses the importance of independent design reviews to catch and correct errors before prototyping, which can save both time and money by reducing the number of necessary iterations.
π‘οΈ Decoupling Capacitors and Enclosure Design
The fifth paragraph discusses the proper use of decoupling capacitors to provide a stable voltage source for critical components. John explains the necessity of placing these capacitors close to the pin requiring stable voltage and the output capacitor near the regulator's output pin. He then transitions to the topic of product enclosure design, highlighting the difference between the forgiving nature of 3D printing for prototypes and the stringent rules of high-pressure injection molding for mass production.
π PCB Landing Patterns and Component Verification
John discusses the common error of incorrect PCB landing patterns, especially when using components not included in standard libraries, which can lead to soldering issues. He suggests a practical method of printing the PCB layout at actual size and manually placing component samples to verify the accuracy of the landing patterns, ensuring that all pins align correctly with the components.
π Via Selection and PCB Manufacturing Costs
This paragraph examines the impact of via selection on PCB design and manufacturing costs. John explains the differences between through vias, blind vias, and buried vias, and how their use can either be restrictive or costly. He advises against using blind and buried vias unless absolutely necessary due to their potential to increase prototype costs significantly, while also noting that these costs are less significant in high-volume production.
β‘οΈ PCB Layout for Switching Regulators
The seventh paragraph focuses on the complexities of designing the PCB layout for switching regulators, which are more efficient than linear regulators but require careful component placement and connection. John emphasizes the importance of adhering to strict layout rules and consulting data sheets for guidance on proper layout techniques.
π Conclusion and Further Learning Opportunities
In the concluding paragraph, John summarizes the video's aim to help viewers avoid common design mistakes and encourages engagement through likes or comments. He introduces himself as John Teal from Predictable Designs and invites viewers to subscribe to the YouTube channel and visit the websites PredictableDesigns.com and TheHardwareAcademy.com for more insights on developing, manufacturing, and selling hardware products.
Mindmap
Keywords
π‘Design for Manufacturing (DFM)
π‘Manufacturability
π‘Wireless Circuits
π‘Impedance Matching
π‘LC Matching Circuit
π‘Manufacturing Costs Estimation
π‘PCB Trace Width
π‘Copper Weight
π‘Independent Design Review
π‘Decoupling Capacitors
π‘Product Enclosure
π‘PCB Landing Patterns
π‘Vias
π‘Switching Regulators
Highlights
Importance of designing for manufacturing (DFM) to avoid delays and costs in product development.
The old way of separating engineering and manufacturing leads to inefficiencies.
Design for testability (DFT) as a subset of DFM for easier product testing during production.
Critical aspects of wireless circuit design including impedance matching for maximum power transfer.
The necessity of using a 50-ohm transmission line and LC matching circuit in RF designs.
Estimating manufacturing costs early to prevent redesigns and budget overruns.
The impact of trace width on PCB designs, especially for high current applications.
The benefits of independent design reviews to minimize prototype iterations and costs.
Misuse of decoupling capacitors and their placement for optimal power supply stability.
Challenges in designing manufacturable product enclosures for high-volume production.
Common errors in PCB landing pattern design and the importance of verifying with physical components.
The role of vias in PCB design and the distinction between through, blind, and buried vias.
Cost implications of using blind and buried vias in prototype boards versus mass production.
Switching regulators' efficiency and the complexities of their PCB layout for optimal performance.
Guidance from data sheets on proper PCB layout for switching regulators.
The video's aim to help eliminate common design mistakes in electronic hardware development.
Encouragement to subscribe for more insights on hardware development, manufacturing, and selling.
Transcripts
there are design mistakes that i see
made over and over again on the
development of new electronic hardware
products so in this video you're going
to discover 10 of the more common design
mistakes that i see and this includes
both specific technical mistakes and
also more general mistakes so there
really is something here for everyone
regardless of your technical level hi
i'm john teal founder of predictable
designs okay let's get started so the
first design mistake that i want to
discuss is failing to design for
manufacturing
people always tend to underestimate the
complexity of developing a new physical
product and they even underestimate more
the complexity of actually manufacturing
it
for many products it takes nearly as
much time and sometimes even more to get
manufacturing set up and running
as it does to actually develop the
product
manufacturing setup can also cost as
much or more than all of your
development cost
so it's really essential that
manufacturability be a primary
consideration during the entire product
design process
and this process is called designed for
manufacturing or designed for
manufacturability or dfm for short
nothing will slow down your path to
market more than designing a product
that you find out can't actually be
efficiently manufactured
the old way of thinking was that
engineers would develop a product and
then they would just pass it on to
manufacturing and manufacturing would
have to actually figure out how to
actually produce the thing and there was
really no interaction between
engineering and manufacturing
but that's a horrible way to develop
products which is why all successful
companies have now abandoned this whole
process
it's much better to develop a product
with manufacturing in mind from the very
beginning
but also don't forget about something
known as design for testability which is
all about designing your products so
that it can be easily tested during
production and this can be kind of
considered a subset of design for
manufacturability the next design
mistake that i want to discuss is the
incorrect design of wireless circuits if
your product has any wireless
functionality then the pcb layout for
any rf portions is going to be super
critical
unfortunately it's done wrong more often
than it is done right so be sure you
watch this one very carefully so the
maximum power transfer between a
transceiver so this could be bluetooth
wi-fi something like that for the
maximum power transfer between that
transceiver and the antenna their
impedance must be matched this means two
things two things are required
first is a proper transmission line
connecting the antenna to the
transceiver
this transmission line is fabricated on
the pcb specifically for carrying
microwaves which are just high frequency
radio waves in most cases the
transmission line is going to need to be
designed with the 50 ohm impedance for
maximum power transfer with the antenna
be sure that you understand that it's
not the resistance of the feed line it's
the impedance the complex impedance it
has between the feed line and the ground
plane that's underneath of it in
addition to using a 50 ohm transmission
line it is also necessary to usually add
some type of lc matching circuit so an
lc is just a simple circuit that
consists of an inductor and a capacitor
so this circuit allows you to fine tune
the impedance so you can get it exactly
right and you can optimize the the
matching the impedance matching between
the antenna and the transceiver so you
get the maximum power transfer
if this matching is not done precisely
then you'll end up losing power
along your feed line and what this will
do is reduce the the operating range for
your wireless functionality so it's
definitely something that you want to
pay close attention to
the next design mistake that i want to
discuss and this one is more general and
less uh it's not a specific technical
mistake like the previous one that we
looked at and this mistake is waiting
too long to estimate the manufacturing
costs for your product successful tech
companies always know approximately how
much a product is going to cost to
manufacture well before they actually
begin developing it otherwise how can
they know the product is actually worth
developing
if you're not a billion dollar tech
company the odds are that you will first
get your product fully designed and then
once you have that final prototype and
you're ready to start manufacturing then
you will finally estimate how much the
product is going to cost to manufacture
but what happens though if you discover
that your product is going to cost more
to manufacture than you expected
you could increase your sales price
target but that obviously has negative
consequences
you could also make some redesigns to
lower the manufacturing costs but
wouldn't it have been
made more sense to just design it right
the first time for understandable
reasons many people think that you have
to fully develop a product before you
can accurately calculate the
manufacturing cost and that is
absolutely untrue
with the right experience it is possible
to accurately estimate the manufacturing
costs for just about any product and
this can happen well before any pcb
layout or 3d modeling occurs the next
design mistake that i want to discuss is
insufficient width for high current pcb
traces
if a pcb trace will have more than
roughly about 500 milliamps of current
flowing through it then in most cases
the minimum width allowed for a trace
probably won't be sufficient
the required width of a pcb trace
depends on several things including the
thickness of the trace which is also
specified as the copper weight
and whether the trace is on an internal
or an external layer so if you have a
four
layer printed circuit board there's two
outer layers or two external layers and
then two internal layers and that makes
a difference on how much current it can
carry
for the same thickness an external layer
can carry more current for the same
width than an internal trace because
external traces have better air flow
allowing them to better dissipate the
heat
the thickness depends on how much copper
is being used for that conducting layer
most pcb manufacturers allow you to
choose from various copper weights from
about
0.0.5 ounces per square foot so that
that's typically the unit is it's in
ounces per square foot so anywhere from
about a half an ounce per square foot up
to about two and a half ounces per
square foot
if preferred you can convert the copper
weight to a thickness measurement such
as mils
and typically when designing printed
circuit boards you're thinking in terms
of mills and if you don't know a mill is
just a thousandth of an inch
when calculating the current
carrying capability of a pcb trace you
must specify the permissible temperature
rise for that trace
now i want to look at a more general
design mistake that i see repeated over
and over and that is not getting an
independent design review done
if you don't get an independent design
review of your product before you
prototype it then you may literally be
throwing money away it doesn't matter
how good of an engineer you may be or
how good the engineer is that you've
outsourced your product design to
no one is perfect and all engineers make
mistakes
shocking i know i can't believe that we
make mistakes but we do
so
getting custom prototypes made whether
we're talking the pcb or the product's
enclosure isn't generally cheap and the
more prototype iterations that you
require the more it will cost in total
it will also take longer to develop and
bring the product to market
one of the best ways to reduce the
number of prototype iterations required
is to get a second opinion called a
design review
successful tech companies always require
their engineers to hold design reviews
to seek feedback from as many other
engineers as possible
now we're going to look at another
design mistake that's a specific
technical design mistake that i've seen
made commonly on printed circuit board
designs and that is the incorrect use of
decoupling capacitors
critical components need a clean stable
voltage source to operate properly and
decoupling capacitors are placed on the
power supply rail to help in this regard
however for the decoupling capacitors to
work their best they must be placed as
close as possible to the pin that's
requiring the stable voltage
also it's critical to place the output
capacitor for the power supply regulator
as close as possible to the output pin
of the regulator for the next design
mistake that we're going to look at
we're going to jump back to the product
enclosure and this mistake is designing
the enclosure for your product so that
it's not actually manufacturable
3d printing is extremely forgiving and
you can really design and print just
about anything your mind imagines
but 3d printing is only for producing a
few prototypes it's not for production
high pressure injection molding is the
technology used for producing plastic
parts in high volume
unfortunately injection molding is not
at all for giving it is a technology
with that requires a lot of design rules
that must be closely followed
these
from the very available
the next common design mistake that i'm
going to look at is incorrect pcb
landing patterns
all pcb design software tools include
libraries of components that are
commonly used these libraries include
both the schematic symbol as well as the
pcb landing pattern
all is usually good as long as you stick
with using the components in these
libraries assuming that they're correct
but from in most cases problems begin
when you
have to use components that are not
included in these libraries this means
the engineer has to manually draw the
schematic symbol and the pcb landing
pattern it's really quite easy to make
mistakes when drawing a landing pattern
for example if you get the pin to pin
spacing
off by just a fraction of a millimeter
then it will make it impossible to
solder the parts on the board because
all the pins won't line up with the
actual part there's a really handy trick
to to help prevent this and that is to
print out your pcb layout on at a
one-to-one scale so that it's exact same
scale as the the final printed circuit
board
then order samples of all the various
components mainly the microchips and the
connectors the more critical components
and then manually place those parts on
your printed out pc
pcb layout
this allows you to very quickly verify
that all the landing patterns are
correct and match the actual part the
next design mistake that i want to
discuss we're going to jump back to the
pcb design again and this mistake is
actually designed into print a circuit
board that either can't be manufactured
or is just exceptionally expensive to
manufacture
and these mistakes will commonly center
around
the types of vias used so a via is just
a conducting hole in a pcb that connects
signals from different layers so if you
have a signal on layer one and you want
to continue routing it on layer four
then you would just via have a via which
is a hole with the conducting material
in it so that the electrical signal can
go from layer one down to layer four
and the most common type of via is known
as a through via and the name through
via comes from the fact that it goes
through all the layers of the board
here you in this image you can see a
cross-sectional view that shows three
types of pcb vias
this one here that's labeled number one
is a through via this means that even if
you only want to connect a trace from
say layer 1 to layer 2
if you're using a through via then all
the layers will also have this via this
can actually increase the size of a
board since the v has reduced the
routing space on layers not even using
the via itself there are two solutions
to this problem if if reducing the size
of your board is of most importance then
you can look at two
types of vias called a blind via
which is like here you can see as shown
that's mark number two in this image
where it connects
layer one to layer two
then the other type of via is a buried
via which is shown as number three here
and a buried via actually connects two
internal layers the problem with blind
and very vias is they have very strict
limitations on which layers they can be
used to connect and it's all too easy to
use a blind or buried via in a way that
can't actually be manufactured or
prototype be warned though that even if
you use blind and buried vias correctly
they will drastically increase the cost
of your prototype boards
many times their use will in fact double
the cost of your prototype boards but
keep in mind this this board increase
will become a lot less significant once
you're you're producing high volume mass
produced boards but it's it's mainly
going to be a financial obstacle when it
comes to the cost to prototype your
board in almost all cases it's really
best to completely avoid the use of
buried and blind vias unless you
absolutely must squeeze every
square millimeter out of that board uh
typically they're not worth the
additional cost
for what little bit of space savings
that they're going to offer okay finally
the number 10 most common design mistake
that i see
is incorrect pcb layout of switching
regulators
so a switching regulator converts one
supply voltage to another by temporarily
storing energy and then releasing it in
the to the output in a controlled
fashion
the storage elements used are inductors
and capacitors for switching regulators
compared to a simple linear regulator
switching regulators are extremely
efficient and waste very little power
however they are much more complicated
to use correctly
one of the biggest complexities of using
switching regulators is correctly
designing their pcb layout you can't
just randomly lay down the components
and connect them up with the switching
regulator there are very strict layout
rules that you need to follow for laying
out a switching regulator correctly
fortunately nearly all data sheets for
switching regulators will include a
section in the data sheet that will show
you the proper way to do the layout and
we'll typically give you an example of
how to do the layout correctly hopefully
this video has helped you eliminate at
least some of the more common design
mistakes that i see made if you have
found it helpful please give me a like
or a comment below i would really
appreciate it i'm john teal with
predictable designs i hope you found
this video helpful and i hope you have a
great day hey there this is john teal
founder of predictable designs if you
enjoyed this video and you want to keep
learning more about developing
manufacturing and selling new hardware
products then be sure to subscribe to
our youtube channel and also check out
the websites predictabledesigns.com
and thehardwareacademy.com
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