in. I’m very cost-sensitive, so
I’m willing to wait two
weeks or more to get my
boards back. You’ll need to
decide what you can
tolerate as far as waits and
prices. Maybe have a couple
different go-to places for
when you might need
something right away or for
when you’re in no hurry. As
always, do searches and
Once you have chosen
the board house you want
to use, just follow their
onsite directions and upload
the folder containing the Gerber and NC
Drill files. Make sure you read their file
submission and design rules. For example,
some might require that your minimum
spacing is 6 mil. That’s actually fairly small.
To give some perspective, the spacing
between the pins on a Q44 chip (like the
Propeller) is 16 mil. Ordering Your Stencil
Ordering a solder stencil is very easy,
especially if you ordered your boards from a
place where the stencil is included with your
order. Then, you’re done already! However,
if you still need to order a stencil, you have
lots of places to choose from.
The first thing to decide is what material
you want your stencil to be made out of: kapton or metal.
Metal costs more than kapton, but will last for thousands of
uses. Kapton stencils will last for hundreds of applications
with proper care, and are perfect for prototyping due to
their cost. A typical metal stencil will cost more than $125
plus shipping, while a kapton stencil will cost approximately
$25 plus shipping. (Refer to Figure 8).
One nice thing you can do with 8. 5” x 11” Kapton
sheets (if the board house allows it) is to fit two smaller
stencils on one sheet to save money.
Ordering a stencil should be very straightforward. Just
follow the instructions for uploading the Gerber file which
is typically called “top paste” for single-sided boards. If
you’re doing a two-sided board, don’t forget to also upload
the “bottom paste.” Ordering Solder Paste and Storage
There are a number of different varieties of solder
paste; some with lead and some that are lead-free. I
normally try and order my solder paste from the same
place I’m getting my stencil from so that I save on shipping.
Just make sure you follow all of the safety instructions and
local laws if you are using lead-based solder paste. I’ve only
used lead-based solder paste myself, so I can’t comment
personally as to which is easier, but I’ve been told that lead-free solder tends to be a bit more difficult to work with.
A number of solder paste manufacturers recommend
that you store it in a cool, dry environment. This helps
prolong shelf life by preventing the solder flux from
evaporating. I picked up a cheap dorm room style fridge
that I store my solder paste in. It is a “non-food” fridge with
a sign on it marking it as such, along with the material
safety datasheet (MSDS). Holding Your PCB with a Stencil Frame
To apply the solder paste, you first need to securely
May 2014 37
Figure 6. Top paste layer preview.
Figure 7. NC Drill Export menu.
Figure 8. Kapton
stencil and PCB.
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