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United States Patent [191 [11] Patent Number: 4,710,707 Knowles Et Al

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United States Patent [191 [11] Patent Number: 4,710,707 Knowles Et Al United States Patent [191 [11] Patent Number: 4,710,707 Knowles et al. [45] Date of Patent: Dec. 1, 1987 [54] HIGH VOLTAGE ELECTRONIC Primary Examiner-Reinhard J. Eisenzopf COMPONENT TEST APPARATUS Assistant Examiner-W. Burns Attorney, Agent, or Firm-Cornelius J. O’Connor; [75] Inventors: Terence J. Knowles, Lincolnshire; Thomas Hill Francis M. Ray, Glenview; Charles E. Shewey, Mundelein, all of I11. [57] ABSTRACT [73] Assignee: Zenith Electronics Corporation, A high voltage electronic component test apparatus Glenview, Ill. includes a test chamber containing a pair of electrodes [21] Appl. No.: 692,583 across which a high voltage is applied and between which a component is placed in circuit by means of a [22] Filed: Jan, 16, 1985 movable component gripper assembly for the testing thereof. Voltage generating and electrical measurement [51] Int. C1.4 . .. G01R 19/15 [52] U S Cl .................... .. 324/158 F; 324/158 R apparatus is coupled to the electrodes for applying a [58] Fina or Search ..................... .. 200/149 A, 149 R; high voltage thereacross and for measuring the result 324/158 R, 158 P, 158 F, 73 PC; 336/84 R, 84 ing current within the electronic component. From the C component testing, the remotely operated gripper as [56] References Cited sembly then removes the tested component from the test chamber and introduces another component for U.S. PATENT DOCUMENTS testing therein. A closed, circulating liquid-vapor sys 611,719 10/1898 Tesla ............................. .. 200/149 R tem coupled to the test chamber introduces an electri 3,268,698 8/1966 Bober et al. .. .. 200/149 A cally inert vapor, such as Freon or a ?uorinated hydro 3,715,662 2/1973 Richelmann .... .. 324/158 F carbon, into the test chamber to prevent arcing and 3,851,287 11/1974 Miller et al. .... .. 336/84 C eliminate leakage currents therein. The dielectric vapor 4,466,746 8/1984 Hancock et al. ............. .. 324/73 PC condenses on the cooled inner walls of the test chamber, FOREIGN PATENT DOCUMENTS collects as a liquid in a lower portion thereof, and flows under gravity to a reservoir where it is heated and re 0466632 8/1975 U.S.S.R. ........................ .. 324/158 F 0886345 11/1981 U.S.S.R. ........................ .. 324/158 R turned to the test chamber in vapor form in a continu ously circulating manner. The test apparatus of the OTHER PUBLICATIONS present invention is capable of measuring currents in the “Probe Cap for Liquid Encapsulated Modules”, by nano-ampere range at kilovolt test voltages. Lockwood et al., IBM Tech. Disc. Bull., vol. 22, #6, 11/79 pp. 2343-2344. 15 Claims, 3 Drawing Figures US. Patent Dec. 1, 1987 Sheet 1 of 1 4,710,707 DIELECTRIC 38 HEATER 82 2? 4,710,707 1 2 change the voltage isolation characteristics of the di HIGH VOLTAGE ELECTRONIC COMPONENT electric material. TEST APPARATUS The present invention represents an improvement over the prior art by providing a high voltage test appa BACKGROUND OF THE INVENTION 5 ratus for electronic components wherein an electrically inert vapor is continuously circulated through a test This invention relates generally to the testing of elec chamber to prevent arcing and stray electrical currents tronic apparatus and is particularly directed to a high therein during the testing of a component. The present voltage test chamber for testing electronic components invention maintains contaminants within the test envi and modules. 10 ronment to a minimum, virtually eliminates loss of the The high speed testing of electronic components is dielectric vapor from the test apparatus, and eliminates commonly used to ensure quality control in production arcing and stray currents within the test chamber even runs. Each component is typically subjected to at least at very high test voltages to permit the accurate mea one test procedure, and frequently more, in order to surement of even very small currents within the compo determine its electrical characteristics ‘under various nent under test. operating conditions. For example, the leakage current Objects of the Invention within a diode across which is applied a predetermined Accordingly, it is an object of the present invention voltage may be measured for determining the blocking to provide an arrangement for the safe, accurate and characteristics of the diode. The charge capacity of a high speed testing of electronic components and mod capacitor or the resistance of a resistor may be mea 20 ules under high voltage conditions. sured with a given voltage applied thereacross in ac It is another object of the present invention to pro cepting or rejecting the components in a production lot. vide a high voltage electronic component test arrange The tendency today is for increased production lot ment having a closed, circulating dielectric vapor sys testing in the form of more individual component tests tem for reducing the possibility of electrical arcing and as well as the high speed testing of increased numbers of 25 for minimizing leakage currents. components within a given production lot for ensuring Yet another object of the present invention is to pro higher component reliability. vide a high voltage test arrangement for electronic In order to prevent arcing, a dielectric medium is components utilizing a dielectric medium which sub typically provided within the test chamber to reduce an stantially reduces sources of inaccurate measurements electric ?eld in the space between the electrodes across arising from dielectric contamination. which the high voltage is applied and with which the A further object of the present invention is to provide electronic component is placed in circuit. Prior art ap a high voltage test chamber particularly adapted for the proaches have generally made use of a dielectric in automatic, high speed testing of electronic components. liquid form for providing this isolation. The use of a A still further object of the present invention is to liquid dielectric, while providing desirable electrical provide a test environment for testing electronic com characteristics in the test ‘chamber, generally compli ponents under very high voltage conditions, e.g., cates the test procedure. For example, following sub greater than 20 kilovolts, wherein extremely small cur mersion in the liquid dielectric, the dielectric must gen rents, e.g., on the order of nano-amperes, may be accu erally be removed from the surface of the component, rately measured. generally by means of a drying process or a rinse-and BRIEF DESCRIPTION OF THE DRAWINGS dry process. This involves additional components, e.g., The appended claims set forth those novel features a heater and/or a blower, in the test procedure. Since which characterize the invention. However, the inven this drying process is typically accomplished outside of tion itself, as well as further objects and advantages the test chamber, the liquid dielectric or rinse solvent 45 thereof, will best be understood by reference to the which evaporates from the components is lost and gen following detailed description of a preferred embodi erally enters the atmosphere. In addition, submersion of ment taken in conjunction with the accompanying the components within the liquid dielectric and their drawings, where like reference characters identify like removal from the test chamber results in additional elements throughout the various ?gures, in which: dielectric loss as some of the liquid dielectric remains FIG. 1 is a simpli?ed schematic diagram of a high upon the components and is removed from the test voltage electronic component test apparatus in accor chamber. The loss of liquid dielectric by either of the dance with the present invention; aforementioned causes is not only undesirable from an FIG. 2 is a sectional view of a portion of the high environmental standpoint, but also is economically un voltage electronic component test apparatus of FIG. 1 acceptable particularly where relatively expensive di taken along sight line 2-2 therein; and electric materials such as Freon and various fluorinated FIG. 3 is a sectional view of the high voltage elec hydrocarbons are utilized. tronic component test apparatus of FIG. 1 taken along Finally, prior art approaches utilizing liquid dielec sight line 3—3 therein. trics suffer from limitations arising from spurious elec tric leakage currents, particularly from contamination DETAILED DESCRIPTION OF THE of the dielectric. These contaminants may be carried PREFERRED EMBODIMENT and introduced into the dielectric liquid by the elec Referring to FIGS. 1, 2 and 3, there are shown vari tronic components themselves. Once suspended in the ous views of a high voltage electronic component test liquid dielectric, its high voltage leakage current char apparatus 10 in accordance with the present invention. acteristics become irregular and unpredictable resulting 65 The high voltage test apparatus 10 includes a housing in reduced test result reliability. Perhaps the most both 12 having a generally cylindrical shape in a preferred ersome contaminant is water which can enter the test embodiment. Within the housing 12 is provided a gener chamber by various means and which can substantially ally cylindrical test chamber 14 formed of electrically 4,710,707 3 4 insulating material extending substantially the entire permit the measurement of an electrical characteristic length of the housing which is open at the top. An of the component. Following testing of the component upper, inner portion of the housing 12 is provided with 66 within the high voltage test chamber 14, the compo an upper insert, or condensation hat, 20 having an aper nent gripper assembly 60 is displaced upwards so as to ture in the center thereof and providing the test cham 5 remove the component from the test chamber, deposits ber 14 with a generally concave upper, inner surface. the tested component in accordance with the next suc Positioned upon an upper portion of the housing 12 and ceeding process step, and engages another electronic the upper insert 20 is a lid, or cover, 16 having an aper component for positioning and testing within the high ture 18 in the center thereof.
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