MIL-PRF-28750F
b.
Type B: Iron-nickel alloy (41 percent Ni): SAE-AMS-I-23011, class 5, ASTM F30.
c.
Type C: Co-fired metallization such as nominally pure tungsten. The composition and application
processing of these materials should be subject to qualifying activity approval.
d.
Type D: Copper core-iron nickel ASTM F30 alloy (50.5 percent Ni). The core material should consist of
copper (oxygen-free) ASTM B170, grade 2.
e.
Type E: Copper core ASTM F15 alloy. The core material should consist of copper (oxygen-free) ASTM
B170, grade 2.
f.
Type F: Copper (oxygen free) ASTM B170, grade 2. This material should not be used as an element of
any glass-to-metal seal structure.
g.
Type G: Iron-nickel alloy (50.5 percent Ni): SAE-AMS-I-23011, class 2 ASTM F30.
6.7.2 Lead finish. The following lead finishes should be considered for meeting the performance requirements of
this specification:
a.
Hot solder dip. The hot solder dip should be homogeneous with a minimum thickness of 60 microinches
(1.52 μm) for round leads and, for other shapes, a minimum thickness at the crest of the major flats of 200
microinches (5.08 μm) solder Sn60 or Sn63). In all cases, the solder dip should extend up and beyond the
effective seating plane for packages with standoffs or within .030 inch (0.76 mm) of the lead or package
interface for leaded flush mounted SSR's. For leadless chip carrier SSR's, the hot solder dip should cover
a minimum of 95 percent of the metallized side castellation or notch and metallized areas above and below
the notch except the index feature if not connected to the castellation. Terminal area intended for SSR
mounting should be completely covered. The hot solder dip is applicable:
(1)
Over electroplated nickel or electroless nickel phosphorous (see 6.7.3), or
(2)
(3)
Over the basis metal. When applied over the basis metal, underplates that is nonconforming, or other
finishes that are nonconforming (such as fused tin less than 200 microinches), hot solder dip should
cover the entire lead to the glass seal or point of emergence of the lead or metallized contact through
the package wall.
b. Tin-lead plate. Tin-lead plating should have in the plated deposit 3 percent to 50 percent by weight lead
(balance nominally tin) homogeneously co-deposited. As plated tin-lead should be a minimum of 300
microinches thick. As plated tin-lead should contain no more than 0.05 percent by weight co-deposited organic
material measured as elemental carbon. Tin-lead plate is applicable.
Over electroplated nickel or electroless nickel phosphorous in accordance with 6.7.3.
(1)
(2)
Over the basis metal.
c.
Gold plate. Gold plating should be a minimum of 99.7 percent gold, and only cobalt should be used as the
hardener. Gold plating should be a minimum of 50 microinches (1.27 μm) and a maximum of 225
microinches (5.72 μm) thick. Gold plating should be permitted only over nickel plate or undercoating in
accordance with 3.6.11.4.
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