1、AIR-CONVECTION-COOLED LIFE TEST ENVIRONMENT FOR LEAD-MQUNTED SEMICONDUCTOR DEVICES ELECTRONIC INDUSTRIES ASSOCIATION STANDARD RS.323 NATIONAL ELECTRICAL MANUFACTURERS ASSOCIATION PUBLICATION No. SK515-1966 Formulated by JEDEC Semiconductor Device Council - Il Il EIA 323 bb 3239b00 ClOb5575 2 PURPOSE
2、 OF STANDARDS These standards, adopted by the Electronic Industries Association and issued jointly by the Electronic Industries Association and the National Electrical Manufacturers Association, were formulated by the Semiconductor Device Council of the Joint Electron Device Engineering Council. The
3、 JEDEC Semiconductor Device Council is sponsored by both EIA and NEMA to develop stand- ards, proposals, and data dealing with semiconductor devices. EIA-NEMA Standards are adopted in the public interest and are designed to eliminate mis- understandings between the manufacturer and the purchaser and
4、 to assist the purchaser in selecting and obtaining without delay the proper product for his particular need. Existence of such standards does not in any respect preclude any member or non-member of EIA or NEMA from manufacturing or selling products not conforming to the standard. Published by ELECT
5、RONIC INDUSTRIES ASSOCIATIBN Engineering Department 2001 Eye Street, N. W., Washington, D. C. 20006 NATIONAL ELECTRICAL MANUFACTURERS ASSOCIATION 155 East 44th Street, New York, N. Y. 10017 0 Electronic Industries Association and National Electrical Manufacturers Association 1966 AU rights reserved
6、Price S.40 Printed in U.S.A. EIA 323 bb m 3234600 00b557b 4 m RS-323 PAGE 1 AIR-CONVECTION-COOLED LIFE TEST ENVIRONMENT FOR LEAD-MOUNTED SEMICONDUCTOR DEVICES (From EIA Standards Proposal No. 882, this Standard zoas formulated under the cognizance of JEDEC Committee JS-12 on Government Specification
7、s and Standards.) FOREWORD There is a definite need for a standard covering the requirements of the Life Test Environment for devices whose ratings are based on Natural-Air-Convection Cooling. Listed below are several re- quirements of such environments taken from MIL-Std.-750 and MIES-19500C. 1. Re
8、f. MIL-Std.-750-Paragraph 4.3.1-Page 6 Permissible temperature variation in environmental chambers.-When chambers are used, specimens under test shall be located only within the working area defined as follows: (a) Temperature variation within working area: The controls for the chamber shall be capa
9、- ble of maintaining the temperature of any single reference point within the working area within * 2C. (b) Space variation within working area: Chambers shall be so constructed that, at any given time, the temperature of any point within the working area shall not deviate more than -Ii 3C from the
10、reference point, except for the immediate vicinity of specimens generating heat. 2. Ref. MIL-S-19500C-Appendix A-Paragraph 20.22.1 Ambient Temperature.-This is the air temperature measured below a semiconductor device in an environment of substantially uniform temperature, cooled only by Natural-Air
11、 Convec- tion and not materially affected by reflective and radiant surfaces. It becomes very difficult to meet these requirements, except on a small scale, without the use of forced-air movement in the working area. However, the use of higher-velocity air movement is not really permitted in an envi
12、ronment defined by Ambient Temperature and Natural-Air Convection. This standard permits the use of a forced-air cooled-environment provided the average junction temperature is the same as that obtained under the ideal conditions of Natural-Air Convection. This standard is limited to devices where m
13、ost ( 90%) of the power dissipation is obtained by convection and radiation losses from the body of the device. A future standard will be prepared on devices where most of the power dissipation is obtained by thermal conduction from the junction to the leads and the mounting connections. (In this ca
14、se, the leads and the mounting connections serve as heat sinks, and only a small amount of the power is dissipated by convection and radiation from the body of the device.) I. Purpose The purpose of this standard is to define the operational life test environmental conditions for lead- mounted, air-
15、convection-cooled semiconductor devices, where most ( 90%) of the power dissipa- tion is obtained by convection and radiation losses from the body of the device. It provides a means for equating, for life test purposes, the effects of a forced-air-cooled environment to that of a Natural-Air-Cooled e
16、nvironment. Thus forced air motion may be used to obtain reasonable tem- perature distribution in the life test area, where many devices are in close proximity while main- taining the same mean value of the junction temperature as would be obtained under a Natural-Air- Cooled environment at the same
17、 power dissipation level. II. Scope This standard is applicable to life testing of lead-mounted semiconductor devices intended for appli- cations in a Natural-Air-Cooled environment where most ( 90%) of the power dissipation is ob- tained by convection and radiation losses from the body of the devic
18、e. EIA 323 bb m 3234600 00b5577 b W 1.500 in. RS-323 PAGE 2 .188 -C .O62 in. .437 +- .O62 in. .750 -C .O62 in. 1.250 +- .O62 in. III. Life Test Conditions To Be Specified (Natural-Air-Cooled Environment) A. Stated Ambient Temperature (TA) B. Electrical operating requirements at the Stated Ambient Te
19、mperature (TA) with Thermal Isola- C. Life Test Mounting Conditions if different from Table I. tion of the leads. IV. Preferred Values of Dimension A TABLE I Mounting Code I Dimension L I DimensionA a b d C Mount i ng I emiconduc tor Devi ce Clip I-L- “L” dimension is the minimum length of lead spec
20、ified on the outline of the semiconductor device. V. Required TM in the Actual Life Test Area The TA1 required for any particular air velocity over the semiconductor device, variations in mount- ing conditions, and variations of the power loss in the device or its electrical operating conditions, is
21、 determined for a given set of conditions by varying the temperature of the circulating air until (Tj Avg.) mean of the semiconductor device is the same as that realized under a Natural-Air-Cooled environment at the Stated Ambient Temperature and stated power loss or electrical rating. Ref. Appendix
22、 A. VI. Environment Conditions of the Working Area of the Life Test Environment With the serniconductor devices energized for a sufficient period of time to have reached thermal equilibrium, the following conditions shall be met. A. Required Air Temperature TA, (1) The space and time variation of th
23、e measured value of TA1 in the working area shall be within a tolerance of f 5% or f 5C (whichever is greater) from the Required Air Tempera- ture TAl. (2) The measured values of the TA1 air temperature are to be taken at various points in the Life Test Working Area at distances of .25 inches to 2 i
24、nches from the body of the semiconductor device on the inlet side of the air current flow. VII. Required Life Test Temperature Measurements (See Note 1) (1) Determination of (TJ Avg.) Mean, See Paragraph III and Appendix A. (2) Determination of the Required TA1 See Paragraph V. (3) Space and Time Va
25、riations of TA1 See Paragraph VI. Note 1. If the ambient temperature of the life test working area meets the requirements of VI. A. (1) , VI. A. (2) with an air velocity less than 120 ft/minute and the normal air convection currents are not impeded, it will not be necessary to determine either the O
26、perating Junction Temperature (Tj Avg.) as required in Appendix A, or the Required Air Temperature TAI as required in Paragraph V. - - - r- EIA 323 66 m 323V600 0065578 8 m RS-323 PAGE 3 VIII. Large Life Test Areas In the case of Large Life Test Areas, it may not be possible to meet the requirements
27、 of Paragraphs V and VI unless the working area is broken up into smaller areas. Then the air velocity, the Required Air Temperature Tai, or changes in the power dissipation in the device or its electrical operating conditions, or all three variables can be adjusted in the smaller working areas unti
28、l the requirements of V and VI are satisfied for the smaller working areas. Changes in the power dissi- pation or the electrical operating conditions are limited to f 5% from the specified value in Para- graph III. APPENDIX A Reference Test Conditions for the determination of TJ Avg. under the Speci
29、fied Life Test Require- ments given in Paragraph III. (1) Approximate minimum size of the enclosure: 10 in. cube. (2) The Average Ambient Temperature (Ta) shall be controlled to a tolerance of k 3% or +- 3C (3) The Average Wall Temperature of the enclosure shall be controlled to a tolerance of t- 3%
30、 (4) The emissivity of the walls of the enclosure shall be .8 or greater. (whichever is greater) from the Stated Ambient Temperature. or f 3C (whichever is greater) from the Stated Ambient Temperature. (5) The semiconductor device shall be located in approximately the center of the working space. Se
31、e Table I for mounting details except the mounting clip is temperature controlled at (TA) 1. (6) Adjust the Ta temperature to the specified value. (7) With the device energized at the specified conditions, adjust the mounting temperature TUT, until it is equal to the Lead Temperature at a point .O94
32、 inches from the body. This is to assure Thermal Isolation of the device. See Paragraph III. (8) Measure Tj Avg. of the device. (9) Repeat steps (6), (7) and (8) on a suitable sample of devices and obtain (Tx Avg.) Mean. (10) The (Tj Avg.) Mean obtained in Step (9) is used in obtaining Tal in Paragr
33、aph V. APPENDIX B Junction Temperature Measurement In the measurement of the TJ Avg. in either the Reference Conditions (APPENDIX A) or in the Actual Life Test Working Area (Paragraphs V and VII) , it may not be possible to use the same Life Test operating conditions, but the same value of power los
34、s in the device must be used when this measurement of Tj Avg. is made. APPENDIX C Symbols (1) Ta-Stated Ambient Temperature (2) Tal-Required Ai+ Temperature under Actual Life Test operating conditions. (3) Tj Avg.-Average Value of the Junction Temperature of an individual device. (4) (T,Avg.) Mean-M
35、ean Value of the Life Test operating Junction Temperature of many devices. (5) TMm-Temperature of the Mounting Clip under the Reference Conditions of the test. (6) TL Avg.-Average Value of the Lead Temperature at a specified point of an individual device. - EIA 323 bb W 3234b00 00b5579 T W RS-323 PA
36、GE 4 APPENDIX D Definitions (1) NATURAL-AIR-COOLED Environment A Natural-Air-Cooled Environment in this standard is considered to be one in which the power loss in the semiconductor device is dissipated by means of Low Velocity Air Currents (those encountered in natural convection environments), by
37、radiation losses from the sur- face of the device, and by an unspecified amount of conduction losses through the leads to the electrical connections. (2) LOW VELOCITY AIR CURRENTS Low Velocity Air Currents in this standard are defined as air currents which have a velocity less than 120 feet per minu
38、te. (3) AMBIENT TEMPERATURE (Natural Air Convection) This is the air temperature measured below a semiconductor device, in an environment of substantially uniform temperature, cooled only by natural air convection and not materially affected by reflective and radiant surfaces. (4) THERMAL ISOLATION
39、Thermal Isolation of the device from the mounting and electrical connections is defined as limiting the conduction losses through the leads to a value less than 10% of the total losses in the device when the device is operated in a Natural-Air-Cooled environment at the stated ambient temperature. Th
40、e case is thermally insulated from the mounting and electrical connections except through a lead which could be grounded to the case. (5) LEAD-CONDUCTION COOLED A Lead-Conduction Cooled device is defmed as one whose internal power losses are dissi- pated primarily ( 90%) by thermal conduction throug
41、h the leads to the mounting connec- tions. (6) STATED AMBIENT TEMPERATURE TA The Stated Ambient Temperature is the specified temperature of the air in which the semi- conductor device is to be operated at the specified life test operating conditions. (7) REQUIRED AIR TEMPERATURE Tai The Required Air
42、 Temperature is the temperature to which the forced cooling air must be raised to compensate for the added cooling effect at higher air velocities. (8) WORKING AREA The Working Area is defined as that particular area in which the semiconductor devices are actually mounted and does not include adjace
43、nt areas. (9) AVERAGE JUNCTION TEMPERATURE TJ Avg. TJ Avg. is the average value of the junction temperature of a given semiconductor device when it is operated under specified conditions. (10) MEAN VALUE OF THE LIFE TEST OPERATING JUNCTION TEWERATURE (TJ Avg.) Mean is the mean value of a sample of the individual semiconductor device junc- tion temperatures TJ Avg. when they are operated under specified life test conditions.
