MIL-PRF-26H
3.4.2.1 Solder dip (retinning) leads. Only the manufacturer or his authorized MIL-PRF-39007 category B or
category C distributor who has previously been approved may solder dip/retin the leads of product supplied to this
specification provided the solder dip/retin process (see appendix A) has been approved by the qualifying activity.
3.4.2.2 Ferrule-terminal resistors. Ferrule-terminal type resistors shall be designed to meet the requirements of
this specification and figure 1 herein (see 3.1).
3.4.2.3 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 6.12).
3.4.2.3 Flat (stack mounting) and tubular, tab-terminal resistors. These resistors shall be designed to meet the
requirements of this specification (see 3.1).
C
L
MAX
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FIGURE 1. Alignment of ferrules.
3.5 Voltage rating. Resistors shall have a rated direct-current (dc), continuous working voltage, or an approximate
sine-wave root-mean-square (rms) continuous working voltage at commercial-line frequency corresponding to the
power rating (see 3.1), as determined from the following formula:
E = √ PR
Where:
E = rated dc or rms continuous working voltage.
P = power rating in watts
R = nominal resistance in ohms
In no case shall the rated dc or rms ac continuous working voltage be greater than the applicable maximum value
specified (see 3.1).
3.6 DC resistance. When resistors are tested as specified in 4.7.2, the dc resistance shall be within the specified
tolerance of the nominal resistance (see 3.1).
3.6.1 Resistance value deviations. All maximum deviations as specified in this section are to be considered
absolute units with the exception of contact resistance adjustments.
3.7 Thermal shock. When tested as specified in 4.7.3, resistors shall not change in resistance in excess of the
value specified (see 3.1), nor show any evidence of mechanical damage. There shall be no change in resistor
coating, enclosure or other part which will result in degradation in performance.
3.8 Short-time overload. When resistors are tested as specified in 4.7.4, there shall be no evidence of arcing,
burning, or charring; the change in resistance shall not exceed the value specified (see 3.1).
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