MIL-PRF-19978 Capacitors, Fixed, Plastic \(Or Paper-Plastic\) Dielectric \(Hermetically Sealed In Metal, Ceramic Or Glass Cases\), Established And Non-Established Reliability General Specification ForThis specification covers the general requirements for established reliability \(ER\) and non-established reliability \(non-ER\), direct current \(dc\), plastic or paper-plastic dielectric, fixed capacitors, hermetically sealed in metal or ceramic or glass cases. Capacitors meeting the established reliability requirements specified herein have failure rate \(FR\) levels ranging from 1.0 percent to 0.001 percent per 1,000 hours \(see 1.2.1.9\). These FRLs are established at a 90-percent confidence level and maintained at a 10-percent producer\'s risk and are based on life tests performed at maximum rated voltage and maximum rated temperature. An acceleration factor of 5:1 has been used to relate the life test data obtained at 140 percent of rated dc voltage at the applicable high test temperature to the rated voltage at the applicable high test temperature. This specification also covers removable mounting retainers for use with applicable capacitors \(see 3.1\). A parts per million \(ppm\) quality system is used for documenting and reporting the average outgoing quality of ER capacitors supplied to this specification. Statistical process control \(SPC\) techniques are required in the manufacturing process to minimize variation in production of ER capacitors supplied to the requirements of this specification.

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MIL-PRF-19978K

4.6.1.2.2.3.1 Rejected lots. In the event of one or more defects, the inspection lot is rejected. The manufacturer

may use one of the following options to rework the lot.

a. Each production lot that was used to form the failed inspection lot shall be individually submitted to the

solderability test as required in 4.6.1.2.2.3. Production lots that pass the solderability test are available for

shipment. Production lots failing the solderability test can be reworked only if submitted to the solder dip

procedure in 4.6.1.2.2.3.1b.

b. The manufacturer submits the failed lot to a 100 percent solder dip using a approved solder dip process in

accordance with appendix A. Following the solder dip, the electrical measurements required in group A,

subgroup 1 tests shall be repeated on 100 percent of the lot. The PDA for the electrical measurements

shall be as for the subgroup 1 tests. Five additional samples shall then be selected and subjected to the

solderability test with zero defects allowed. If the lot fails this solderability test, the lot may be reworked a

second time and retested. If the lot fails this second rework, the lot shall be considered rejected and shall

not be furnished against the requirements of this specification.

4.6.1.2.2.3.2 Disposition of sample. The solderability test is considered a destructive test and samples submitted

to the solderability test shall not be supplied on the contract.

4.6.2 PPM calculations (non-ER and ER). The manufacturer shall establish and maintain a system for assessing

and calculating average outgoing quality of capacitors. A PPM rate combining IR, capacitance, and DF shall be

assessed for lots that have passed the group A inspection. The manufacturer's PPM system shall also address

rectification procedures for lots failing PPM assessment. Data from the rectification process shall not be used to

calculate PPM.

4.6.3 Periodic group B inspection. Periodic group B inspection shall consist of the tests specified in table XIV in

the order shown, and shall be performed on sample units selected from lots that have passed group A inspection.

Except where the results of this inspection show noncompliance with the applicable requirements (see 4.6.3.4),

delivery of products which have passed group A shall not be delayed pending the results of this periodic inspection.

4.6.3.1 Sampling plan.

4.6.3.1.1 For all non-ER styles and FRLs. Sample units shall be selected from the first lot and then from every

two months production for subgroups 1, 2, 3, 4, and 5. The highest watt-second rating in each style, characteristic,

and voltage manufactured during the specified periods shall be represented in at least the approximate ratio of

production. A different sample shall be selected for each subgroup.

4.6.3.1.2 For FRLs M, P, R, and S. In addition to the tests specified in 4.6.3.1.1, a minimum ten sample units

from each inspection lot (see 4.6.3.1.1) shall be subjected to subgroup 3 of table XIV. Allowable failures shall be as

specified in table IV of MIL-STD-690.

4.6.3.2 Failures. If the number of failures exceeds the number allowed in table XIV, the sample shall be

considered to have failed.

4.6.3.3 Disposition of sample units. Sample units which have been subjected to group B inspection shall not be

delivered on the contract or order.

4.6.3.4 Noncompliance (applicable to both ER and non-ER parts). If a sample fails to pass group B inspection,

the manufacturer shall notify the qualifying activity and cognizant inspection activity of such failure and take

corrective action on the materials or processes, or both, as warranted, and on all units of product which can be

corrected and which were manufactured under essentially the same conditions, with essentially the same materials

and processes, etcetera, and which are considered subject to the same failure. Acceptance of the product shall be

discontinued until corrective action, acceptable to the Government, has been taken. After the corrective action has

been taken, group B inspection shall be repeated on additional sample units (all inspections, or the inspection which

the original sample failed, at the option of the Government). Group A inspection may be reinstituted; however, final

acceptance shall be withheld until the group B reinspection has shown that the corrective action was successful. In

the event of failure after reinspection, information concerning the failure and corrective action taken shall be

furnished to the qualifying activity and the contracting officer or purchaser.