4. If possible, an ID logo or part number within the layout will help distinguish the
substrate. Lettering should be made of 4-5 mil wide lines.
5. Any critical area on the substrate that needs to be toleranced at +/-0.5 mils or better must
be dimensioned on the substrate drawing.
6. The etch factor is: 1.2 mils per side for 1 oz. Copper
.6 mils per side for .5 oz. Copper
7. For substrates to be gold plated, the whole pattern should be electrically interconnected
using 5 mil shorting bars. Refer to paragraph 4.
4.3
Mask
Layout
Duroid masks do not have a saw kerf between each substrate. It is assumed that when duroid
is cut into individual substrates, no material loss occurs. The mask is a film type with the
pattern stepped into a 2" x 2" array (in-house use) or larger. The mask pattern should be a
positive image.
4.4
Plating Call Out
Bondable:
Electroless Nickel per MIL-C-26074, Class 2, .0001-.0002 thick.
Gold plate per MIL-G-45204, Type III, Class 2, .000075-.00150 thick.
Solderable:
Electroless Nickel per MIL-C-26074, Class 2, .0001-.0002 thick.
Gold plate per MIL-G-45204, Type III, Class 2, .000010-.000025 thick.
5.0
MASK
ORDERING
5.1
Glass Masks: Ceramic Substrates Only
The glass masks used are 4 inch square glass plates with a 2.0 inch (or smaller)
square array stepped on the plates. The stepped array is of positive polarity with the
substrate pattern being right-reading emulsion down for etch-back substrates but
negative polarity on the plate-up substrates. For resistor layer, polarity is negative.
Glass masks are used in the following cases:
· engineering prototypes with critical dimensions or thin-film resistors
· all production substrates on ceramic with critical dimension or thin-film resistors
Glass masks are ordered either in emulsion or chromium plated.
5.2
Film Masks: Ceramic or Duroid Substrates
The film masks used are mylar films with a 3.0 inch (or smaller) square array stepped
film. The stepped array is of positive polarity with the substrate pattern being right-
reading emulsion down.
Nanowave Confidential
Thin-film Guidelines/ Page 22 of 22