MIL-PRF-38535K
APPENDIX A
A.3.5.6.2 Lead or terminal material. Lead or terminal material shall conform to one of the following compositions:
a. Type A: Iron-nickel-cobalt alloy: SAE-AMS-I-23011, class I, ASTM F15.
b. Type B: Iron-nickel alloy (41 percent nickel): 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 shall be subject to QA approval and submitted with application to test and as
otherwise requested by the QA.
d. Type D: Copper-core, iron-nickel ASTM F30 alloy (50.5 percent nickel). The core material shall consist of
copper (oxygen-free), ASTM B170, grade 2.
d. Type E: Copper-core ASTM F15 alloy. The core material shall consist of copper (oxygen-free)
ASTM B170, grade 2.
f. Type F: Copper (oxygen-free) ASTM B170, grade 2. This material shall not be used as an element of any
glass-to-metal seal structure.
g. Type G: Iron-nickel alloy (50.5 percent nickel): SAE-AMS-I-23011, class 2, ASTM F30.
h. Type H: Tin-lead alloy solder balls, bumps or columns.
i. Type J: Tin-lead alloy with copper spiral columns.
A.3.5.6.3 Microcircuit finishes. Finishes of all external leads or terminals and all external metal package elements
shall conform to either A.3.5.6.3.2 or A.3.5.6.3.3, as applicable. The use of pure tin, as an underplate or final finish, is
prohibited both internally and externally. The tin content of solder shall not exceed 97 percent. Tin shall be alloyed
with a minimum of 3 percent lead by weight. The lead finish designator (see A.3.6.2.7) shall apply to the finish of the
leads or terminals. The leads or terminals shall meet the applicable solderability and corrosion resistance
requirements. The other external metallic package elements (including metalized ceramic elements) shall meet the
applicable corrosion resistance requirements. Finishes on interior elements (e.g., bonding pads, posts, tabs) shall be
such that they meet the lead bonding requirements and applicable design and construction requirements. The use of
strike plates is permissible to the maximum thickness of 10 microinches (0.25 micrometer). All plating of finishes and
undercoats shall be deposited on clean, nonoxidized metal surfaces. Suitable deoxidation or cleaning operations
shall be performed before or between plating processes. All parts shall be capable of meeting the following
requirements of MIL-STD-883:
a. Test method 2004, lead integrity, test condition B1, B2, or D, or test method 2028, pin-grid package destructive
lead pull test, as applicable.
b. Test method 1009, salt atmosphere.
c. Test method 2003, solderability (plus time/temperature exposure of burn-in except for devices which have
been hot solder dipped or have undergone tin fusing after burn-in).
d. Test method 2025, adhesion of lead finish.
Note: Compliance to the above requirements shall be demonstrated when and as specified.
A.3.5.6.3.1 Finish thickness measurements. Lead finish thickness measurements shall be taken at the seating
plane on surface mount leads (such as J-bend and gull-wing type leads) and approximately halfway between the
seating plane and the tip of the lead on all other lead types. (This requirement is to avoid having the inspector select
a non-typical portion of the lead on which to perform the measurement.) On all lead shapes other than round, the
finish thickness measurement shall be taken at the crest of major flats. Measurements taken on the shorting bar shall
be correlated by direct measurement on the lead. Finish thickness measurements for package elements other than
leads shall be taken at the center of major flats. Finish thickness measurements shall be performed in accordance
with one of the following procedures:
a. ASTM B487.
b. ASTM B567.
c. ASTM B568.
The aforementioned ASTM methods are provided as reference methods to be used when the failure to pass other
finish requirements suggests deficiencies in plating thickness. Compliance to the finish thickness requirements shall
be demonstrated when and as specified.
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ACTEL [ Actel Corporation ]
