SD-15 Guide For Performance SpecificationsThis document provides guidance information on performance specifications focusing primarily on stating requirements in performance terms and ensuring that sufficient verification means are included in the specification to evaluate conformance. While the focus of this document is on defense specifications developed under DoD 4120.24-M, Defense Standardization Program DSP Policies and Procedures, the principles and techniques can also be applied to program unique performance specifications, performance-based purchase descriptions, commercial item descriptions, or any other type of procurement specification. This guide is intended to supplement the format and content requirements for writing performance specifications found in MIL-STD-961, Defense and Program-Unique Specifications Format and Content.

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Performance Specification Guide SD-15

EXAMPLE 8 - PROCESS REQUIREMENTS

Using the non-mandatory Section 6, Notes, in specifications to provide guidance on past solutions that may fulfill the performance requirement can be a useful approach. However, this approach should be used carefully so as not to convey an unintended message that alternative solutions will not be accepted by the Government. Also, the guidance should reflect current industry practices and technology. In the following example from detail specification MIL-S-8805D, Switches and Switch Assemblies, Sensitive, Snap Action (Basic Limit, Push Button and Toggle Switches), the specific process specifications were removed from the detail specification. Possible plating and hot solder dip processes were provided as guidance in the Section 6, Notes, in the performance specification MIL-PRF-8805E. Notice that the suggested processes were updated and expanded from the former mandatory processes in the detail specification. Both the detail military and revised performance specification can be viewed in their entirety on the ASSIST database athttps://assist.daps.dla/quicksearch/.

MIL-S-8805D, Switches and Switch Assemblies, Sensitive, Snap Action (Basic, Limit, Push Button and Toggle Switches)

MIL-PRF-8805E, Switches and Switch Assemblies, Sensitive, Snap Action (Basic, Limit, Push Button and Toggle Switches)

3.5.2 Terminals. Terminals shall be as specified (see 3.1 and 6.2).

3.5.2.1 Solder terminals. Solder terminals shall be treated to facilitate soldering. Coatings such as hot solder or hot-tin dip are acceptable. Gold plating shall not be used, except when solder lug terminals are integral

with gold contacts, gold plating 0.000030 inch to 0.000100 inch may be used. Silver plating shall not be used as the external coating.

3.5.2.2 Printed circuit board terminals. Printed circuit board terminals shall be tin-lead plated or solder dipped. Tin-lead plating shall be 100 microinches minimum in accordance with

MIL-P-81728. Solder dip shall be 60-40 tin- lead in accordance with QQ-S-571, 100 microinches minimum thickness.

3.5.2 Terminals. Terminals shall be as specified (see 3.1 and 6.2).

3.5.2.1 Solder terminals. Solder terminals shall be treated to facilitate soldering. Coatings such as hot solder dip are acceptable. Gold plating

0.000030 inch minimum may be used and shall be over a diffusion barrier such as nickel or palladium. Silver plating shall not be used as the external coating. For additional information and guidance on plating, see 6.14.

3.5.2.2 Printed circuit board terminals. Terminals intended for direct soldering into printed circuit boards shall be metal alloy plated or solder dip. Tin-lead composition may be used. Plating shall be 100 microinches minimum. For additional information and guidance on tin-lead plating and hot solder dip see 6.14.

(THIS IS THE GUIDANCE FROM THE SECTION 6 NOTES)

6.14 Terminal finishes and plating.