MIL-PRF-55110 Printed Wiring Board, Rigid, General Specification ForThis specification establishes the performance and qualification requirements for rigid single??sided, double??sided, and multilayered printed wiring boards with or without plated through holes \(see 6.1\). Verification is accomplished through the use of one of two methods of product assurance \(QPL or QPL/QML\). Detail requirements, specific characteristics, and other provisions which are sensitive to the particular intended use are specified in the applicable master drawing.

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MIL�PRF�55110G

APPENDIX E

E.3

E.3. DEFINITIONS

E.3.1

E.3.1 Sequential Electrochemical Reduction Analysis (SERA). A chronopotentiometric reduction method for

assessing tin-lead finish solderability.

E.4

E.4. TESTING

E.4.1

E.4.1 Apparatus (see figure E�1).

E.4.1.1

E.4.1.1 Reservoir (see detail A). The reservoir shall be a container constructed of a nonmetallic, nonreactive

material with a minimum volume of 500 ml. The reservoir shall have an inlet/outlet port, test head chamber port, and

a saturated calomel electrode (SCE) reference electrode port. The inlet/outlet port shall be connected to a vacuum

trap tube. The inlet/outlet port shall incorporate a diffuser to aid in the effectiveness of the inert gas purging.

Polypropylene tubing may be used for connection tubing. All connection fittings shall be of a nonreactive material.

The reservoir shall have the capability of maintaining a positive pressure environment. The reservoir shall be emptied

and rinsed with deionized water for every 16 hours of testing.

E.4.1.2

E.4.1.2 Test head (see detail B). The test head shall be constructed of a nonmetallic, nonreactive material. The

test head shall have ports to allow inert gas purging and intake/expulsion of borate buffer solution. The test head

shall have either an optical or mechanical means of aligning the test head chamber over the test plated-through hole.

The test head shall use Vitron or equivalent o-rings for the test head to test surface interface seals. These o-rings

shall be replaced after every 8 hours of testing unless integrity of the o-rings can be documented for extended

periods. The test head shall have the capability of maintaining a positive pressure environment.

figure E-1 FIGURE E�1

FIGURE E�1. Schematic of SERA plated through hole apparatus.