MIL-STD-981C
5.1.4.3 Termination limitations. Internal wire leads shall be attached to the coils and other internal components and terminals or case by soldering (see 5.5.10), welding, brazing, crimping or other method in such a manner as to provide adequate electrical connection and mechanical strength. However, devices with smaller diameter gauge than AWG 36, the wire shall be terminated within the device and a wire larger than AWG 36 shall be used to connect to the terminal. Twisting smaller gauge wires (such as AWG 36) and soldering to form a larger lead may fulfill the requirements for terminating with larger wires. Where soft solder is used to provide the electrical connection, wire leads shall be anchored mechanically. Wire sizes shall conform to the limits of Table III. Terminations shall be such that adequate stress relief
is provided for all leads. Procuring activity approval shall be required when other terminations are used.
TABLE III. Termination Limitations (see 5.1.4.3).
Type of Termination |
Minimum Terminal/Self Lead Wire Size (AWG) |
|
Class S |
Class B |
|
Interconnected Lead External terminal/self lead 1/ |
29 26 |
32 28 |
1/ Spliced internal lead diameter ratios shall not exceed 5 to 1 for magnet wire sizes larger than #44.
5.1.5 Solder and soldering flux. Solder, when used, shall be in accordance with J-STD-005, and J- STD-006, except that pure tin shall not be used. Soldering flux shall be in accordance with J-STD-004, Type L0 or L1 for class B and S.
5.1.5.1 Internal Solders. To prevent internal solder reflow, devices shall utilize higher solder melt temperatures than assembly reflow. Internal solder shall have a minimum melt temperature of 260°C.
5.1.6 Screws, nuts, and washers. All mounting and terminal screws, nuts, and washers shall be protected against corrosion. Cadmium, Zinc, or Tin-plating shall not be used on any surface exposed to space environment. All materials shall be compatible and not support galvanic corrosion or tin whisker growth.
5.1.7 Recycled and recovered material. Under no circumstances should recycled or recovered materials be used in space level devices, unless specifically approved by the acquiring activity.
5.2 Internal elements. Packaged or unpackaged parts (other than the wound magnetic elements) used within these devices shall be approved by the acquiring activity. The request for approval must justify the need for the part and provide sufficient data to substantiate the suitability of the part in the application. Procurement documentation for the part shall be submitted to the procuring activity for approval.
5.3 Radiographic inspection (when applicable). Devices shall be inspected in accordance with
Appendix B.
5.3.1 Real time x-ray analysis. Real-time x-ray with images (provided as part of the data package) shall be performed with a view of overall construction and two side views of each individual device. Images shall be provided in digital media format. Devices shall be carefully analyzed for winding, core, termination and with close-up views of any anomalous conditions. Devices shall meet the workmanship and x-ray criteria specified herein for class S parts. 2 views minimum and the 3rd view when applicable.
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