All photoplot and photomask orders must specify the polarity and
image surface orientation desired. Please use the Laserlab, Inc. designations
when placing your order. These are found in the first column of the table below.
Definitions
A phototool is a photoplot made of flexible photographic film or a photomask made of
a coating applied to a glass or quartz substrate.
Data areas are those containing text, vectors, or filled areas as drawn in the CAD program.
Field areas are non-data areas; these are the empty spaces outside the
figures drawn in the CAD program. The field extends to the edge of the mask, or nearly so.
The emulsion side is the image surface on silver-halide films and plates.
The chrome side is the image surface on chrome-on-quartz masks.
Positive phototools (photoplots and masks) are
dark (opaque) in the data areas and clear (transparent) in the field areas.
Negative phototools are clear (transparent) in
the data areas and have a dark (opaque) field.
Right-reading means that text or other figures inserted into the CAD database in normal,
left-to-right reading fashion appear in the same orientation on the phototool as they do when viewing
in the CAD system using the conventional viewpoint. The conventional CAD system viewpoint is a view
from above, looking down and through the image layer or layers.
Emulsion/chrome Up phototools are right-reading when
the image surface faces toward you.
Emulsion/chrome Down phototools are right-reading when
the image surface faces away from you.
Negative-acting photoresist cross-links upon exposure to UV light, so it becomes resistant to attack from
the development chemicals where the photomask or photoplot is transparent. This means the photoresist remains
after development wherever the photomask is clear. Dark areas of the photomask prevent cross-linking, so the
photoresist is removed upon development.
Positive-acting resist decomposes (long polymer molecules break apart) upon exposure to UV light,
so the resist is removed during development wherever the phototool is transparent. Dark areas
of the phototool prevent exposure to UV light, so those areas remain after development.
Phototool Type Designations
Laserlab Designation
Image Examples
Phototool Polarity
Image Surface
Purpose
CAD Image
Phototool Image
Polarity
Data Areas
Field Areas
Orientation
Mirrored
PU
Positive
Dark
Clear
Up
No
silkscreen master; exposure on bottom side of substrate coated with positive-acting resist
PD
Positive
Dark
Clear
Down
Yes
exposure on top side of substrate coated with positive-acting resist
NU
Negative
Clear
Dark
Up
No
exposure on bottom side of substrate coated with negative-acting resist
ND
Negative
Clear
Dark
Down
Yes
exposure on top side of substrate coated with negative-acting resist
Green areas in the CAD image column are data areas.
Light blue areas in CAD image column are non-data (field) areas.
All graphics in the Phototool Image column indicate how the phototool will appear with the
emulsion or chrome (image surface) facing you.
The white areas in the Phototool Image column are transparent on the phototool.
The black areas in the Phototool Image column are opaque on the phototool.
The Polarity, Data Areas, Field Areas, Orientation, and Mirrored columns indicate how the
phototool will appear with the emulsion or chrome (image surface) facing you.
Example 1 -- top-side of wafer using positive-acting resist
You have a silicon wafer you are going to pattern with metal twice
using a spin-on positive-acting photoresist. The CD (critical dimension) is 20um.
This means no lines or spaces are smaller than 20um on the phototool.
Very-High-Resolution (8000 DPI or 1/8 mil resolution) is a good
choice for this scenario.
Your order form should look something like this:
Laserlab Photoplot order form:
file # file name plot type quantity
------ ------------------- ----------- ----------
1 metal1.gbr VPD 1
2 metal2.gbr VPD 1
Note: H = high resolution, V = very high resolution
N = negative, P = Positive
U = right reading emulsion up, D = right reading emulsion down
Example 2 -- two-sided subtractively etched PCB
You have a two-sided through-hole PCB you are going to print and etch using the standard
subtractive process and want to order one set of working film. High-Resolution
(4000 DPI or 1/4 mil resolution) is adequate because your minimum feature size is more
than 5 mils. The solder mask is the LPI (Liquid Photo Imageable)
type, applied to both sides with the same pattern, and you are going to apply a conventional
screen-printed legend to the top side. Negative-working photoresist is typically used for
this application.
Your order form should look something like this:
Laserlab Photoplot order form:
file # file name plot type quantity
------ ------------------- ----------- ----------
1 trace_top.gbr HND 1
2 trace_bot.gbr HNU 1
3 silk_top.gbr HPU 1
4 smask.gbr HPD 1
4 smask.gbr HPU 1
Note: H = high resolution, V = very high resolution
N = negative, P = Positive
U = right reading emulsion up, D = right reading emulsion down
