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This section is devoted to giving a manufacturer’s
view of PCB design (design for manufacturability).
Our goal is to produce the circuit boards
on time, at lowest cost, and which meet
all your requirements. You can help us in
this objective by observing the following
guide lines.
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avoid delay please submit following information
with your order: |
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Hole Size and Pad Size: |
For
power and ground layers, make the pad size
0.045 in larger than the hole size. For
component, solder and inner layers make
the pad size 0.017 in larger than the hole
size. It allows more room for drilling and
decreases the chances for shorts. Soldermask
pads should be 0.005 in. larger than the
soldering pad
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| Draws
and Flashes: |
When
designing a board, try to limit the amount
of draws you use. Draws use a lot of memory
and slows the programming time. Ex.: Use
a flash for pads instead of draws. If for
some reason we need to increase or decrease
that pad size, it can easily be done by
changing the D-code, if they are done with
draws it could be a nightmare.
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| Silkscreen
rules: |
Keep
silkscreen at least 0.006 in away from pads
(except vias). The minimum line thickness
is 0.008 in and the minimum letter height
is 0.100 in. Ensure that no silkscreen falls
on any pads this could effect the soldering
process. Avoid printing component outlines,
aspecially if you are using automatic assembly.
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| Routing: |
To
speed programming - add a borderline to
one of your files, this will give us a route
reference for routing the PCB to size
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| Order
in Larger Quantities: |
Price
per board is significantly lower when ordered
in higher quantity. We offer a split delivery
option that allows you to get a lower per
board price without the extra cost on your
part for maintaining an inventory.
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| Quick
Delivery time: |
Most
companies charge a premium for quicker than
two weeks turn around, therefore allow as
much time as possible.
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| Avoid
paying Tooling charges twice: |
Avoid
paying tooling charges twice by selecting
a single vendor who is competitive for quick
turn prototype as well as production run.
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| Hole
sizes: |
Hole
sizes smaller than 0.020, especially in
boards thicker than .062 boards, limits
the number of panels which can be drilled
at the same time, therefore, adding cost
to the drilling operation and high aspect
ratios which makes plating difficult. Also,
limit the number of different hole sizes.
Review your design to see what flexibility
you have with the hole sizes.
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| Annular
ring: |
Try
to provide at least a 10 mil annular ring.
A smaller annular ring creates manufacturing
difficulties which result in lower yield
and higher cost.
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| Line
width and spacing: |
Manufacturing
cost increases significantly when line width
and spacing drop below 10 mil, so you should
avoid them if your application does not
require such fine line and space.
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| Blind
and Buried Vias: |
The
use of blind and buried vias can increase
the unit cost by up to 50 %, therefore,
use them only if you have compelling reasons.
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| Layer
Stackup: |
If
you have flexibility in your layup specification,
discuss with your vendor, he may have some
cost effective suggestion using his standard
materials.
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| Panel
Layout: |
If
you can be flexible with your panelized
PCB panel size, consult your PCB vendor
to discuss the size. This will allow the
manufacturer to arrange the maximum number
of boards on their standard panel size.
This may have a major impact on cost especially
in production quantities. Many manufacturing
costs are the same for small or large panel
size.
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| Electrical
Testing: |
The
complexity involved in making the test fixture
depends on factors such as; type of board
(Thru hole or SMT one side or SMT both side),
number of test points, spacing between pads
(pitch), therefore, the cost of test fixture
can vary from $200 to over $1000. Also,
testing would add 1-2 days to manufacturing
cycle. So consider the cost and time factors
when deciding if you want Electrical Testing
or not.
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Electro-Circuits, Inc. -
All Rights Reserved. |
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