MIL-PRF-28750F
6.7.3 Nickel plate or undercoating. Electroplated nickel undercoating or finishes from a sulfamate nickel bath is
preferred and should be 50 microinches to 350 microinches (1.27 μm to 8.89 μm) thick measured on major flats or
diameters. Electroless nickel undercoating or finishes, when allowed, should be 50 microinches to 350 microinches
(1.27 μm to 8.89 μm) thick measured on major flats or diameters. The addition of organic "wetting agents" is
prohibited for either sulfamate or phosphorous nickel baths. Electroplate or electroless nickel plate (or combinations
thereof) as well as nickel cladding may be used as the finish for package elements other than flexible leads or
terminals provided the corrosion resistance and environmental requirements are met. In all cases, electroplated
nickel undercoating from a nickel sulfamate bath is preferred for lead finishes. Electroless nickel should not be used
as the undercoating on flexible or semiflexible leads (see 3.3.1 and 3.3.2 of MIL-STD-883, method 2004) and should
be permitted only on rigid leads or package elements other than leads.
6.7.4 Tin plated finishes. Use of tin plating is prohibited (see 3.7). Use of tin finishes can result in whisker growth.
Tin whisker growth can result in adverse effects on the operation of electronic equipment systems. For additional
information on this matter, refer to ASTM B545 (Electrodeposited Coating of Tin).
6.7.5 Solder dip (retinning) leads. Only the manufacturer, at their option, may solder dip/retin the leads of the
product supplied to this specification provided the solder dip/retin process has been approved by the qualifying
activity.
6.8 Sealing (degassing). The following procedure is suggested as a guide; however, every effort should be made
to utilize the most effective procedure consistent with the state of the art.
a.
Evacuate to less than 200 micrometers.
Heat to maximum rated ambient temperature with continued evacuation (see 3.1).
b.
c.
Maintain heat and vacuum for 12 hours or longer, continuing the treatment until a maximum pressure of 80
micrometers is reached.
d.
Turn off heaters and maintain pressure for four hours.
e.
Close evacuation valve and fill chamber with the desired inert pressurizing gas.
f.
Seal SSR before removing from chamber.
6.9 PIN. This specification requires a PIN that describes technology and appropriate references to associated
6.10 Environmentally preferable material. Environmentally preferable materials should be used to the maximum
extent possible to meet the requirements of this specification. As of the dating of this document, the U.S.
Environmentally Protection Agency (EPA) is focusing efforts on reducing 31 priority chemicals. The list of chemicals
is available on their website at https://www.epa.gov/epaoswer/hazwaste/minimize/chemlist.htm. Further information is
available at the following EPA site: https://www.epa.gov/epaoswer/hazwaste/minimize/. Included in the EPA list of 31
priority chemicals are cadmium, lead, and mercury. Use of the materials on the list should be minimized or eliminated
unless needed to meet the requirements specified herein (see Section 3).
41
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business