MIL-PRF-49465 Resistor, Fixed, Metal Element, Power Type, Very Low Resistance Values, General Specification ForThis specification covers the general requirements for power type, low value \(1 ohm and below\), fixed resistors \(2 terminal and 4 terminal\) for use in electrical, electronic, communications, and associated equipment. Included are precision resistors of ??1 percent, ??3 percent, and ??5 percent initial resistance tolerances with power ratings ranging from 3 watts to 5 watts at +25 degrees C derated to 0 power at +275 degrees C.

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MIL-PRF-49465C

3. REQUIREMENTS

3.1 Specification sheets. The individual item requirements shall be as specified herein and in accordance with the

applicable specification sheet. In the event of any conflict between the requirements of this specification and the

specification sheet, the latter shall govern (see 6.2).

3.2 Qualification. Resistors furnished under this specification shall be products which are authorized by the

qualifying activity for listing on the applicable Qualified Products List (QPL) at the time of award of contact (see 4.4

and 6.3).

3.3 Material. The material shall be as specified herein. However, when a definite material is not specified, a

material shall be used which will enable the resistors to meet the performance requirements of this specification.

Acceptance or approval of any constituent material shall not be construed as a guaranty of the acceptance of the

finished product.

3.3.1 Pure tin. The use of pure tin, as an underplate or final finish, is prohibited both internally and externally. Tin

content of resistor components and solder shall not exceed 97 percent, by mass. Tin shall be alloyed with a

minimum of 3 percent lead, by mass (see 6.4).

3.4 Interface and physical dimension requirements. Resistors shall meet the interface and physical dimensions as

specified (see 3.1).

3.4.1 Construction. Internal construction shall consist of a metallic resistive element that has no joints, welds, or

bonds, except at end terminals where welding, brazing, or silver solder only shall be employed. The resistive element

shall be as free as practicable from particles or impurities, grain growth, or other factors contributing to spot

weakness. Where abrasive resistance value adjustment is used, the abrasion must be evenly distributed across the

resistive element.

3.4.1.1 Protective coating or enclosure. Resistor assemblies shall be protected by an enclosure of moisture

resistant insulating material that shall completely cover the exterior of the resistance element, including connections

or terminations. This material shall afford adequate protection against the effects of prolonged exposure to high

humidity. The enclosure shall be free from holes, fissures, chips, and other faults. Small cracks and molding flaws

which do not adversely affect the unit's ability to meet all environmental requirements of this specification will not be

considered a cause for rejection.

3.4.1.2 Terminals. Terminals shall be made of a solid conductor of the length and diameter as specified (see 3.1).

3.4.1.2.1 Solder dip (retinning) leads. The manufacturer may solder dip/retin the leads of product supplied to this

specification provided the solder dip/retin process (see appendix) has been approved by the qualifying activity.

3.4.1.3 Weight. Resistors shall not exceed the maximum weight as specified (see 3.1).

3.5 Power rating. Resistors shall have a power rating based on continuous full load operation at an ambient

temperature of +25 C (see 3.1). For temperatures in excess of +25 C, the load shall be derated in accordance with

figure 1.