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1、- E I A 229-A 65 m 3234600 0063420 7 m - % r *- 3 O 4 U S A S C83.32-1968 Approved July 24, 1968 USA STANDARDS INSTITUTE oc iA Fixed, Wire -Wound, 4 Y Precision Resistors cy N 8 EIA STANDARD R S- 2 2 9 m A (Revision of RS-229) May 1965 Engineering Department ELECTRONIC INDUSTRIES ASSOCIATION 7 - Cop
2、yright Electronic Components, Assemblies the first four digits represent significant figures and the last digit, the number of zeros to follow. When the value of resistance is less than 1,000 ohms, or when fractional values of an ohm are required, the letter “R” is substituted for one of the signifi
3、cant digits to represent the decimal point. When the letter “R” is used, succeed- ing figures become significant figures. TABLE VI1 Designation 1R000 to 9R999 incl. IOROO to 99R99 incl. 100RO to 999R9 incl. 10000 to99990 incl. 10001 to99991 incl. 10002 to99992 incl. 10003 to99993 incl. Resistance Va
4、lue (Ohms) 1.000 to 9.999 incl. 10.00to 99.99 incl. 100.0 to 999.9 incl. 1,000 to 9,999 incl. 10,000 to 99,990 incl. 100,0001 to 999,900 incl. 1,000,000 to 9,999,000 incl. Copyright Electronic Components, Assemblies the change in resistance shall not exceed the resistance tolerance specified in the
5、type designation or O.l%, whichever is smaller. 4.2.6 Temperature Cycling (a) Mounting, temperature conditions, and measurements. Resistors shall be mounted in such a manner that there is at least 1” of free air space around each resistor, and in such position with respect to the air stream that the
6、 mounting offers substantially no obstruc- tion to the flow of air across and around the resistor. The rate of temperature change within the climate chamber shall be not less than 2C per minute. The temperature shall be maintained at each of the extreme temperatures by means of circulating air. The
7、air temperature shall be measured by a suitable method and as near the center of the group of resistors as possible. (b) Procedure. Resistors shall be subjected to the temperature cycle shown in table below for a total of five cycles performed continuously. The resistors ,may be transferred from one
8、 chamber to another, in which case they shall be kept at room temperature for not less than 10 minutes and not more than 15 minutes between exposure to the extreme temperatures. Measurements of resistance shall be made before cycling and not less than 1 hour, but within 24 hours after the iast cycle
9、. Copyright Electronic Components, Assemblies one group shall be subjected to load and the other group to polarization. (e) Load. During steps 1 and 4, rated (100%) wattage or maximum rated voltage, whichever is smaller, shall .be applied for the first 2 hours of each step. (f) Polarization. During
10、steps 1 to 6 inclusive, a 100-volt d.c. potential shall be applied to the three remaining units with positive connected to the resistance element, and negative connected to the mounting plate. (8) Subcycle. During step 7, at least 1 hour but not more than 4 hours after step 7 begins, the resistors s
11、hall be removed from the humidity chamber in order to perform step “a, after which the resistors shall be returned to the humidity chamber and kept there until the next cycle begins. (h) Number of cycles. Resistors shall be subjected to 10 continuous cycles, each cycle as shown on Figure 1 of latest
12、 issue EIA Standard RS-186. (j) Final measurements. Upon completion of step 6 of the final cycle, the resistors shall be held at the high humidity condition at 25 f 2C for a period of 11/2 to 31/2 hours, after which the resistance shall again be measured as specified in step c. NOTE : Final insulati
13、on resistance measurements to be made at room temperature outside the box within 10 minutes after removal, (k) As a result of the resistors being tested as specified above, resistors shall show no evidence of breaking, cracking, spalling, or loosening of terminals or mounting hardware. The initial i
14、nsulation resistance shall not be less than 500 megohms. The final insulation resist- ance shall be not less than 100 megohms. The d.c. resistance shall not change more than 1.0% between the initial and final measurements, 4.2.9 Dielectric Strength (a) Resistors shall be tested in accordance with la
15、test issue EIA Standard RS-186, Method 4, Dielectric Test. (b) Mounting. Resistors shall be mounted on a conductive material which will conform to the resistor surface so that at least 90% of the outer periphery is contacted, (c) Procedure. An a.c. potential of 500 volts shall be applied for 1 minut
16、e between the resistor terminals, connected together, and the conductive material. (d) As a result of the test specified above, there shall be no flash over, evidence of breakdown of insulation, or change in resistance in excess of 0.05%. 4.2.10 Terminal Strength (a) Axial wire lead terminal resisto
17、rs. Resistors shall be firmly clamped and a pull of 5 pounds shall be applied to each terminal, one at a time, in a direction along the horizontal axis of the resistor. After the pull has been removed, all terminals shall be bent through 90“ at a point %jf from the body of the resistor, with the rad
18、ius of curvature at the bend approxi- Copyright Electronic Components, Assemblies the initial plane shall pass through the resistor axis and terminals, and the other two planes shall be mutually perpendicular. (b) Upon completion of the vibration test, units shall be tested for resistance. The resis
19、tance shall not change more than 0.1% and there shall be no mechanical damage. 4.2.12 Temperature Coeflcient of Resistance (a) The resistors shall be maintained for 30 to 45 minutes within 3“ at each of the following ambient temperatures: *25O, 145“, *25“, and -55“ consecutively. At the end of each
20、period, the resistance shall be measured again, at the temperature maintained during the period. The temperature coefficient of resistance, referred to a reference temperature of 25C shall then be computed as follows : AR X 100 TC = R X A t Where : TC = Temperature coefficient in percent per degrees
21、 C. R = Resistance at reference temperature. A R = Change in resistance at test temperature from resistance at reference temperature. A t = Difference between test and reference temperature in degrees. *This temperature shall be considered the reference temperature for the succeeding extreme tempera
22、ture. (b) As a result of the test specified above, the temperature coefficient of resistance of the resistors, referred to an ambient temperature of 25“C, shall not exceed the applicable value specified in paragraph 2.4. Copyright Electronic Components, Assemblies & Materials Association Provided by
23、 IHS under license with ECA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 03:04:53 MDTNo reproduction or networking permitted without license from IHS -,-,- E I A 229-A b5 3234b00 0063430 T i s- RS-229-A Page 9 O 4.2.13 Load Life (a) Test conditions. This test shall
24、 be conducted at an ambient temperature of 125” f 5C. Rvsistors shall be supported by wire leads with an effective length of 1 inch and shall be so arranged that the temperature or any one resistor shall not influence appreciably the temperature of any other resistor. There shall be no undue draft o
25、ver the resistors. Each resistor shall dissipate rated (100%) wattage, and adequate precaution shall be taken to maintain constant voltage on the resistors. At no time shall the voltage applied exceed the maximum voltage specified. (b) Procedure. Initial resistance shall be measured after 24 hours o
26、f exposure at 126” 2 6C. Following the measurement of initial resistance, d.c. voltage, as specified in 4 . 2 . 1 3 (a) shall be applied intermittently, 1% hours on and 1/2 hour off for a total of 2000 hours. Resist- ance measurements shall be made at the end of the 1/2 hour off period after 100 f 8
27、, 250 f 12, 500 2 12, 1000 -t- 12, and 2000 + 72 - O hours. (c) As the result of the test specified above resistors shall withstand the test specified without mechanical damage to the resistance element coating, or enclosure. The resistance change between the initial measurement and each succeeding
28、measurement shall not exceed 0.5%. 4.2.14 Solderability Resistors shall be tested according to EIA Standard RS-178-A, Solderability Test Standard. Both leads shall be tested and the solder immersion shall be to within 0.062” of the resistor body. After immersion the leads shall have a new uniform co
29、ating over a minimum of 95% of the surface being tested. The balance of the surface may contain only small pinholes, dewetted areas, rough spots, or uncoated baae metal provided that such defects are not concentrated in one area. NOTE: To show that 5% of the area is a reasonable maximum limit, 5% of
30、 the circumferential area for a 0.033” diameter wire, is approximately 6 voids of 0.033” diameter in a 1 inch length. 5. MATERIALS AND CONSTRUCTION 5.1 Terminals Terminals to which it is intended to solder connectors shall be suitable for easy soldering. Hot solder, electro-tin, electro-solder, or t
31、in-dipping are acceptable commercial practices. 5.2 Resistance Wire The resistance wire shall possess a substantially uniform cross section of conductor and insulation. The wire shall be as free as practical from particles of impurity or other factors contributing to spot weakness. The cross section
32、al area of the wire shall be maximum consistent with other requirements of this specification. The wire diameter and type shall be at the discretion of the supplier following accepted manufacturing procedures. 5.3 Core and Enclosure Materials Core material and enclosure material used for resistors s
33、hall be of such type and quality as will permit complete resistors to meet the qualification as specified. 6. APPLICATION, NOTES, AND DEFINITIONS 6.1 Supplementary Insulation for Mounting Where high voltages (600 volts R.M.S.) are present between resistor circuit and grounded surface on which the re
34、sistor is mounted, or where the resistance value is so high that the insulation resistance to ground is an important factor, secondary insulation shall be provided between the resistor and mounting or between mounting and ground. Copyright Electronic Components, Assemblies & Materials Association Pr
35、ovided by IHS under license with ECA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 03:04:53 MDTNo reproduction or networking permitted without license from IHS -,-,- RS-229-A Page 10 E I A 229-A b5 = 3234600 00b343L II 6.2 When resistors are mounted in rows or banks
36、, they shall be so spaced that, taking into consid- eration the restricted ventilation and heat dissipation by the nearby resistors, none of the resistors in the banks or row exceeds its maximum allowable rating according to Figure 2. 4 6.3 A.C. Characteristic Normally these units are usable from d.
37、c. to 1OK.C. However, for applications where ax. character- istics are critical, standards should be established between purchaser and manufacturer. 6.4 Mounting va. Vibration Normally these resistors are intended for mounting by their leads, however, where unusual vibra- tion and shock stresses are
38、 encountered, it is preferable that additional mounting be employed. 6.5 Noise Level Noise level of these resistors is inherently low, approaching the thermal agitation level, 6.6 Stability Where used within the design limits specified herein, the typical change in resistance with life will not exce
39、ed 60% of the initial resistance tolerance. 6.7 Soldering When soldering resistors into a circuit, for best results, extreme care should be used. The smallest iron possible, consistent with good hot solder joints should be used, If possible, the soldering should be done no closer than %“ away from t
40、he body of the resistor. Excessive heat may cause a signifi- cant change in the initial resistance. 6.8 Wattage Derating for Close Tolerance When using close tolerances for critical applications the following wattage limits are recommended : a InitzcCl Tolerance 0.6 0.26 0.1 0.06 Maximum “/. of Rate
41、d Wattage 76 50 60 26 6.9 Voltage and Wattage Never exceed the maximum voltage or maximum wattage. 6.10 Resistance Values Beyond the Standard Range Where resistance values above or below the range specified are absolutely essential the user should negotiate with several manufacturers to make sure th
42、at the parts manufactured will meet his requirements. It should be understood that these pa& do not normally meet the requirements of this specification. 6.11 Application Note Where temperature coefficients of less than +20 ppm are required, they can be obtained by special selection of the resistanc
43、e wire. Temperature coefficients of +lo ppm may be obtained by limiting the temperature range for test from -40C to $105“C. Where possible, the application of tempera- ture coefficient to resistors should be limited to the actual temperatures at which the equipment will operate. 6.12 Compliance with
44、 Tests and Specifications The sample scheme or percentage of any shipment which shall be subjected to tests outlined in this standard is a matter for determination beween the vendor and the purchaser, a Copyright Electronic Components, Assemblies & Materials Association Provided by IHS under license
45、 with ECA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 03:04:53 MDTNo reproduction or networking permitted without license from IHS -,-,- E I A 229-A 65 3234600 O063432 3 I &- RS-229-A Page 11 7. METHODS OF TEST 7.1 Measuring Equipment Limit of error of resistance
46、bridge for measurements shall be 0 . 1 % or resistance tolerance whichever is less plus 0.002 ohm. of the specified initial a 7.2 Application of Voltage Test Voltages shall be applied 3/8 f Yi6 from the end of the resistor body (for 10 ohms or less). The following voltage shall be used for initial a
47、nd all subsequent tests. Nominul Resistance (ohm) 1 to 9.999 incl. 10 to 99.99 incl. 100 to 999.9 incl. 1000 to 9999 incl. 10000 to 99990 incl. 100000 and higher Maximum Test Voltage (volts) 0.3 1 . 0 3.0 10.0 30.0 100.0 Copyright Electronic Components, Assemblies & Materials Association Provided by IHS under license with ECA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 03:04:53 MDTNo reproduction or networking permitted without license from IHS -,-,-