CHAPTER 1: GENERAL REQUIREMENTS

3E100 APPLICABLE DOCUMENTS

The following documents form a part of this publication to the extent specified herein. Unless otherwise specified, the issue in effect on date of invitation for bids or request for proposals shall apply. Copies of documents required in connection with a specific procurement may be obtained from the procuring NASA installation or as directed by the contracting officer.

The X-ray equipment shall have sufficient voltage range to produce radiographs in accordance with this standard and the following requirements:

1. Voltage Range. The voltage range shall be sufficient to produce a focal spot of 3.5 millimeters (mm) and to maintain a sharply defined image at a focal film distance of 36 inches minimum.

2. Sensitivity. The X-ray equipment shall be capable of detecting particles with a major dimension of 0.001 inch.

3. Film. The X-ray film shall be of a grade defined as very fine grain or equal and may be either single or double emulsion.

4. Exposure. Exposure factors such as plate potential, current, and time shall be compatible with the sensitivity requirements of subpar. 2.

5. Film Density. The X-ray equipment and processing techniques shall be capable of producing H and D film density of 1.5 to 2.5 in accordance with the American Standard Printing density type P-2, in the applicable area as defined in Standard MIL-STD-453.

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6. Film Dimensions. All radiographic film shall be standard 7 x 17 inches, 8 x 10 inches, 10 x 12 inches, or 35-mm film strip of the required length.

7. Processing. The exposed X-ray film shall be processed in recommended solutions and in such such a manner to be free of processing defects, i.e., fingerprints, chemical spots, blemishes,

etc.

8. Penetrameters. Penetrameters shall be employed in all radiographic testing and shall be as specified in Table I and Figure 1 or Table II and Figure 2. The penetrameter image shall be used to determine radiographic quality. The penetrameter image shall meet the following requirements:

a. All penetrameter wires shall be visible on each radiograph.

b. Penetrameters shall be selected to give a radiographic density within 10 percent of the density of the specimen under examination.

c. Penetrameters shall be placed in diagonal corners on the source side of the film. The plane of the penetrameters shall be normal to the radiation beam. When 35-mm film strip is used, the penetrameter shall be placed in a position occupied by a part, and a penetrameter image shall be made (exposed) for every 50 parts or 17 in. of film, whichever is more convenient.

d. Distortion of any penetrameter shall not exceed 10 percent. e. The spacing between wires of a penetrameter shall not be distorted by more than 10 percent. The percentage of distortion as used in this standard is defined as follows:

S1 = wire spacing as it appears on the X-ray film.

9. Fixtures. Suitable fixtures shall be used for mounting the microcircuits during the X-ray operation.

10. Radiation Filters. The requirements for the use of screens and filters to give better definition and sensitivity follows:

a. Lead backing plates, 1/8-inch thick shall be used with cassettetype film holders for all voltages, 150 KVP and below.

b. Lead diaphragms shall be used to isolate specimens from each other when more than 4 specimens are radiographed on the same film.

c. Barium clay masking may be used provided the barium clay is of sufficient thickness to insure that the film density under the clay is approximately one-half that under the specimen.

d. Where practicality permits, metallic shot may be used for masking large singular specimens.

e. Lead-foil screens may be used provided commercially-pure lead or a 94.6 percent lead-antimony compound is used as base materials.

f. Liquid absorbers shall not be used.

3E102 RADIOGRAPHIC VIEWING EQUIPMENT

The radiographs shall be examined on a suitable illuminator with variable intensity or on a viewer suitable for radiographic inspection on projection type viewing equipment. A magnification of 7 power minimum shall be used for radiograph examination.

3E103 IDENTIFICATION

Each microcircuit shall be readily identified by a serial number. They shall be radiographed in consecutive, increasing serial order. When a microcircuit is missing, the blank space shall contain either the serial number or other X-ray opaque objects to readily identify and correlate X-ray data.

3E104 MARKING

The microcircuits that have been X-rayed and have been found acceptable shall be identified with a blue dot on the external case. The blue dot shall be approximately 1/16 inch in diameter and shall be of fungus-resistant paint. The paint color shall be any shade ranging between numbers 15102-15123 and 25102-25109 as specified in Standard Fed-STD-595. The dot shall be placed in such a manner as to be readily visible but shall not obliterate other device marking.

3E105 RADIOGRAPHIC PROCEDURE

1. Mounting. The microcircuits shall be positioned and mounted in a manner that will permit compliance with subpar. 4 and the detail requirements contained in Chapter 2. See Figures 3, 4 and 5 for typical layout. The microcircuits may be mounted in any type of fixture, provided that the fixture is not between the body of the microcircuit and the film.

2. Film Identification. Each radiographic film shall be identified with the following information:

a. Microcircuit manufacturer's name.

b. NASA part number.