MIL-STD-202G
3.2 Exposure parameters. The following exposure parameters may be varied to obtain the radiographic quality specified in 2.1:
a.Source - film distance.
b.Kilovoltage or type of isotope.
c.Milliamperage or source strength of isotope.
d.Exposure time.
e.Film speed.
f.Intensifying screen.
The detail sensitivity is affected by the following:
a.Focal spot size.
b.Film grain size.
c.Nature of the specimen.
d.Placement of the specimen.
The above factors should be taken into consideration when determining the exposure parameters.
3.3Intensifying screens. In general, metallic intensifying screens should be used at X-ray tube voltages above 125 kilovolts to minimize fogging and for intensifying effects.
3.4identification of radiographs. Suitable means shall be employed to identify individual specimens on the radiographic record.
3.5Marking of radiographed specimens. If required, suitable marking shall be specified in the individual specification indicating that specimens have been inspected radiographically.
4. EVALUATIONS. The final image shall be examined with suitable viewing equipment, which may include magnification, to determine such defects as improper positioning of elements, voids in encapsulating or potting compounds; inhomogeneities in materials; presence of foreign materials; broken elements; and other defects as specified in the individual specification.
METHOD 209
18 May 1962
2
MIL-STD-202G
5.SUMMARY. The following details are to be specified in the individual specification:
a.Required radiographic quality (see 2.1 and 4).
b.Image-quality indicator to be used (see 2.3).
c.Records, if required for nonfilm techniques (see 2.5).
d.Position or positions of specimen (see 3.1).
e.Marking indicating that specimens have been radiographed, if required (see 3.5).
f.Evaluation of images (see 4).
(1)Specific kind of viewing equipment, if required.
(2)Magnification, if required.
(3)Defects to be sought in the specimen.
METHOD 209
18 May 1962
3
MIL-STD-202G
METHOD 210F
RESISTANCE TO SOLDERING HEAT
1.PURPOSE. This test is performed to determine whether wire and other component parts can withstand the effects of the heat to which they will be subjected during the soldering process (solder iron, solder dip, solder wave, or solder reflow). The heat can be either conducted heat through the termination into the component part, or radiant heat from the solder bath when in close proximity to the body of the component part, or both. The solder dip method is used as a reasonably close simulation of the conditions encountered in wave soldering, in regard to radiated and conducted heat. This test also is intended to evaluate the impact of reflow techniques to which components may be exposed. The heat of soldering can cause solder reflow which may affect the electrical characteristics of the component part and may cause mechanical damage to the materials making up the part, such as loosening of terminations or windings, softening of insulation, opening of solder seals, and weakening of mechanical joints.
2.APPARATUS.
2.1Solder pot. A static solder pot, of sufficient size to accommodate the mounting board (see 2.4) and to Immerse the terminations to the depth specified for the solder dip (without touching the bottom of the pot), shall be used. This apparatus shall be capable of maintaining the solder at the temperature specified. The solder bath temperature shall be measured in the center of the pot at a depth of at least .500 inch (12.7 mm), but no deeper than 1 inch (25.4 mm) below the surface of the solder.
2.2Heat sinks or shielding. The use of heat sinks or shielding is prohibited except when it is a part of the component. When applicable, heat sinks or shielding shall be specified in the individual specification, including all of the details, such as materials, dimensions, method of attachment, and location of the necessary protection.
2.3Fixtures. Fixtures, when required, shall be made of a non-solderable material designed so that they will make minimum contact (i.e., minimum heat sink) with the component. Further, they shall not place undue stress on the component when fixtured.
2.4Mounting board. A mounting board, in accordance with NEMA grade FR-4 of IPC-4101, 9 square inches
(i.e., 3 x 3, 1 x 9, etc.), minimum area, .062 inch ±.0075 inch (1.57 mm ±.191 mm) thick, shall be used, unless otherwise specified. Component lead holes shall be drilled such that the diametrical clearance between the hole and component terminals shall not exceed .015 inch (0.38 mm). Metal eyelets or feed-throughs shall not be used. Surface mount boards, when specified in the individual specification, shall have pads of sufficient size and number to accommodate the component being tested.
2.5Solder iron. A solder iron, capable of maintaining a temperature of 350°C ±10°C, shall be used.
2.6Reflow chambers. The reflow chambers or equivalent (Vapor Phase Reflow (VPR) chamber, Infrared Reflow (IRR) oven, air circulating oven, etc.) shall be of sufficient size to accommodate the mounting board and components to be tested. The chamber shall be capable of generating the specified heating rate, temperatures, and environments.
2.7Temperature measurement. Low mass thermocouples that do not affect the heating rate of the sample shall be used. A temperature recording device is recommended. The equipment shall be capable of maintaining an accuracy of ±1°C at the temperature range of interest.
3. MATERIALS.
3.1 Solder. The solder or solder paste shall be tin-lead alloy with a nominal tin content of 50 percent to 70 percent in accordance with ANSI/J-STD-006, “Requirements for Electronic Grade Solder Alloys and Fluxed and Non-Fluxed Solid Solders for Electronic Soldering Applications” or ANSI/J-STD-005, “Requirements for Soldering Pastes”. When specified in the individual specification, other solders can be used provided they are molten at the specified temperature.
METHOD 210F
8 February 2002
1 of 7
MIL-STD-202G
3.2Flux. When flux is used, it shall conform to type A of ANSI/J-STD-004, “Requirements for Soldering Fluxes”, or as specified in the individual specification.
3.3VPR fluid. A perfluorocarbon fluid that has a boiling point of 215°C shall be used.
4. PROCEDURE.
4.1Special preparation of specimens. Any special preparation of specimens prior to testing shall be as specified in the individual specification. This could include specific instructions such as bending or any other relocation of terminations, cleaning, application of flux, pretinning, or attachment of heat sinks or protective shielding (see 2.2), prior to the solder immersion.
4.2Preparation of solder bath. The molten solder shall be agitated to assure that the temperature is uniform. The surface of the solder shall be kept clean and bright.
4.3Application of flux. When flux is used, the terminations to be tested shall be immersed in the flux (see 3.2), which is at room ambient temperature, to the depth specified for the solder dip. The duration of the immersion shall be from 5 seconds to 10 seconds.
4.4Test conditions. Unless otherwise specified in the individual specification, the test shall be performed on all solder terminations attached to the component part. There are six types of soldering techniques covered by these test conditions. The test conditions are outlined below and in table I.
Test condition A: |
Solder iron - Hand soldering of solder cups, through hole components, tab and post |
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terminations, solder eyelet terminations. |
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Test condition B: |
Solder dip - Simulates hot solder dipping (tinning) of leaded components. |
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Test condition C: |
Wave solder - |
Simulates wave solder of topside board mount product. |
Test condition D: |
Wave solder - |
Simulates wave solder of bottomside board mount product. |
Test condition H: |
VPR - VPR environment without preheat. |
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Test conditions I, J, K: |
Infrared/Convection reflow - Simulates IRR, natural convection, and forced air |
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convection reflow environments. |
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4.4.1 Test condition A: Solder iron.
a.When testing a solder cup, tab and post termination, or solder eyelet termination, the applicable wire size, properly prepared for the solder termination, shall be attached in the appropriate manner.
When testing a board mount component, the component shall be placed on a mounting board (see 2.4).
b.When specified, the components shall be fluxed (see 4.3).
c.Unless otherwise specified, a solder iron in accordance with 2.5 shall be used.
d.The solder iron shall be heated to 350°C ±10°C and applied to the termination for a duration of 4 seconds to 5 seconds as specified in table I. The solder and iron shall be applied to the area of the assembly closest to the component body that the product is likely to experience. For surface mount components, the iron shall be placed on the pad only.
METHOD 210F
8 February 2002
2