KR20010095420A - Device for enhancing contact checking - Google Patents

Abstract

PURPOSE: An improved contact test apparatus is provided to increase sensitivity of a test apparatus in a field of the presence of an electronic element such as a small-sized ceramic chip capacitor. CONSTITUTION: An HP4349B high resistance meter(1) has a toroid transformer(3). The toroid transformer(3) is connected with an input circuit of the HP4349B high resistance meter(1) through three wires(5,7,9), a DC current measurement group(13), a high frequency measurement group(15), and a blocking capacitor(17). A right side of the second wires(7,9) is connected with an active internal conductor(19) and an active internal guard shield(21). A left side of the second wires(7,9) is connected with a high frequency measuring group(15) and a ground through a blocking capacitor(17). A booster portion(45) has a transformer(49). The transformer is formed with the first and the second wires(43,51).

Description

Contact inspection improvement device {DEVICE FOR ENHANCING CONTACT CHECKING}

The present invention relates to the field of small electrical device measurement and inspection. In particular, the present invention provides devices for improving the performance of high resistance electrical measuring instruments such as Hewlett Packard 4349B and devices for increasing the sensitivity of such instruments in the field of "Parts Present" below the minimum limits of their existing range. It is about how to use.

In the field of small ceramic electric capacitor chips capable of measuring external dimensions as small as .02 OX.020x.040 inches and exhibiting capacitances of less than 1 picofarad (pF), some DC leakage current is generated through the portion. It is known that there is a limited parallel conductance. Since capacitor chips are essential for computer operation and many other electronic devices, it is important to classify these chips by measuring direct current (DC) leakage current. In the prior art, a high resistance measuring instrument such as Hewlett Packard Model 4349B is used.

In the ceramic capacitor (chip) industry, the Hewlett Packard 4349B meter was connected to a high speed device “handler” or processing machine that measured DC leakage current through these capacitors at high throughput rates. These handlers take unchecked capacitor chips and take them individually or in parallel to the test station, where the handler checks the capacitor terminals for the DC leakage test (current limiting power supply on one side and HP 4349B or the other). To a high resistance / low current measurement device). Before or after the leak test, the measuring instrument performs a test protocol, "part present" or "contact test" to verify the presence of the capacitor at the test station with both sides properly connected to the test circuit. This protocol is for the inspection station to ensure that the parts are properly connected in the inspection circuit, since parts with high leakage characteristics can be classified as "good" parts.

In the case of BP 4349B, and triac cable and its mechanism is connected to the LO side of the DUT (D evice U nder T est) by (triax cable), the inner conductor of the cable is carrying a DC current signal from the DUT, The inner shield carries a high frequency (HF) guard signal of about 0.5 MHz (Mega Hertz) generated within 4349B at the time of “parts present”, and the triac's outer shield is grounded.

In addition, the HI side of D.U.T., which is directly connected to the power supply, is grounded at high frequency. During the "component present" check, the HF signal driving the guard is applied by 4349B to the internal inductor of the triac cable at the same amplitude. Thus, in the absence of a suitable connection to an existing or non-existent ceramic capacitor, the HF current flowing through the guard (with its outer end open) is equal to the current flowing through the inner conductor so that the component will not be detected. will be. However, in the case of a proper connection to an existing part at the inspection station, these currents will not be the same and the properly connected part present will be recognized by 4349B. When a "NO PART PRESENT" classification has been performed, this classification requires re-inspection of any parts that existed in the inspection station, and takes precedence over any classification derived from leakage current inspection.

The drawback of this prior art practice is that parts with capacitance values less than 2 pF are often undetected, even if proper inspection is made at the inspection station.

The present invention is a device and a method of using the device in which the HP4349B determines whether the part is present and whether good contact is made, even if the part has a capacitance value as low as 0.75 pF at the inspection station. For this device, it has a "signal booster" which is a transformer, amplifier or other equivalent element having a differential input driven from an internal guard shield and an external ground shield of the HP4349B input triac cable. The device's output is connected in series with the output from the high-voltage limiting power supply and added to the HF guard voltage via the DUT derived directly from the 4349B, in any way "presenting parts within the HP-4349B without internal modification of this proprietary mechanism. "The sensitivity of the detection circuit and the amplitude of this signal can be increased.

In particular, one aspect of the present invention relates to an electronic device in which the second or third inspection of the inspection instrument is performed by a high frequency signal superimposed through the detection of the presence of the element in the inspection station and through a device-under-test. It is possible to increase the minimum sensitivity of the second or third inspection of the inspection instrument having an important function of inspecting the electronic elements for the critical parameter (resistance, capacitor or inductor). "Proper connection" means an ohmic value that is low enough not to compromise the accuracy of critical inspection or any other function of the instrument.

It is therefore a primary object of the present invention to provide a means for determining the presence of a DUT at an inspection station before a high resistance leak test is performed. Another object of the present invention includes an apparatus and a method using the same for verifying that the inspection circuit will be the value of the capacitor of the inspection station, which is disclosed on the ceramic chip capacitor and what is written in, in order to perform the electrical leakage inspection. Means for completing the electronic inspection of electrical leakage to reduce the time it takes to increase the usefulness of the inspection machine of other capacitors, and to increase the throughput of the ceramic chip capacitors of the device handler to reduce its operating time and thereby Means for reducing the production cost of ceramic chip capacitors, means for lowering the cost of ceramic chip capacitors by increasing the efficiency of the capacitor inspection machine, and for testing for the presence of capacitors having a capacitance of 2.0 pF or less. Ceramic capacitor inspection machine performance By increasing the capital expenditures for equipment inspection.

1 is a schematic diagram of a conventional "contact inspection" or "part present" circuit using a Hewlett Packard (HP) 4349B test apparatus;

FIG. 2 is a schematic diagram of a preferred embodiment of the present invention with the same circuit modified as shown in FIG.

Explanation of symbols on the main parts of the drawings

1: HP4349B high resistance meter 3: toroidal transformer

5, 7, 9: Winding 13: DC current measuring group

15: high frequency measurement group 17: blocking capacitor

19: Active Inner Conductor 21: Active Inner Guard Shield

25: first triac cable 27: inspection station

29 signal line 31 high voltage power supply

33: capacitance of the HI-side conductor 37, 39: capacitor

41: second trach cable 43: first winding

45 booster device 49 transformer

51: second winding

These and other objects of the present invention can be determined by reading the description of the preferred embodiment according to the accompanying drawings. The spirit of protection seen by the inventor can be found from the clear reading of the claims, including this specification.

In all the drawings, elements are given the same reference numerals, and identical elements are given the same reference numerals. 1 shows a typical inspection system for determining the leakage value of a ceramic chip capacitor. While the present invention is illustrated with respect to ceramic chip capacitors, those skilled in the art will appreciate that other situations in which the present invention needs to electronically check for the presence of a device under test (DUT) and proper electrical contact therewith. It will be appreciated that it can be used in.

For the HP4349B, it has four identical input channels for leak measurements, but for clarity only one channel is shown and described. It will be appreciated that the present invention is composed of four channels in total.

Referring to FIG. 1, the HP4349B High Resistance Meter 1 includes three windings 5, 7, 9, a DC current measurement group 13 and a high frequency measurement group 15, a blocking capacitor 17. Is shown to include a toroid transformer 3 having an input connected to the input circuit of the HP4349B. During the " part present " check, the high frequency generator obtained from the transformer 3 via the first winding 5 is not shown. This signal is also connected to the high frequency measurement group 15 for phase modulation purposes.

The second windings 7, 9 comprise a small number of windings of the coaxial cable so that a very identical output from both sides is assured. The right side of these two windings connects to the active inner conductor 19 and the active inner guard shield 21 of the first triac cable 25 respectively. The left side of the second windings 7, 9 is connected to the high frequency measurement group 15 and ground respectively via a blocking capacitor 17. The same is due to the amplitude of the signals generated from the second windings 7, 9, Since the inner guard shield 21 has a low capacitance to ground at its outer end, the amplitude of the signal input to the high frequency measurement group 15 is directly related to the capacitance to the ground of the active inner conductor 19 at its outer end. It can be estimated to be proportional.

The active internal conductor 19 passes from the high resistance meter 1 to the lo- side of the DUT test station 27. The hi-side of the DUT inspection station 27 passes through a signal line 29 through a high voltage power supply 31 which typically has a range of 0-500V. The ground shield 39 of the first triac cable 25 also passes through a power supply 31.

The right side of the DUT inspection station 27, i.e., the signal line 29, has a relatively low impedance compared to ground due to the capacitance of the hi-side conductors 29 and 33, and the actual output impedance of the power supply 31, Fig. 1 And a capacitor 37 in FIG. 2. Therefore, the capacitance of the ground of the active inner conductor 19 at its outer end is approximately equal to the sum of the stray capacitance of the ground of the inspection station 27 (and symbolically represented by the capacitor 39) and the actual capacitance of the DUT. Can assume

During the initial compensation cycle of the HP4349B, the inspection station 27 is empty and the digitized output of the high resistance meter 1 thus obtained is stored in the memory. Then during the "Part Presence" inspection, this value is extracted from the digitized value obtained when the part is speculatively placed in the inspection station 27 to obtain an evaluation of its presence and proper contact at the inspection station 27. This method, during the compensation cycle, if the value of stray capacitance 37 is high, such as 10 pF, compared to that of the DUT of the inspection station 27, such as 1 pF, the former value creates the latter value and thereby There is one limitation that makes the system unresponsive to the presence of the DUT or chip when the value of the DUT is very low.

During the leak test, a programmed high voltage output from the power supply 31 is applied to the right side of the DUT of the test station 27 so that its DC leakage current passes through the active internal conductor 19 of the first triac cable 25. Is generated and the second winding 9 is applied to the input of the DC measuring group 13.

The invention which added the external circuitry of this HP4349B mechanism is shown in FIG. A common T-adapter, which is provided with a second triac cable 41 and provides a signal on the active inner guard shield 21 to the input 43 (first winding) of its booster device 45, represented here as a transformer. Not shown) to the first triac cable 25. The second winding 51 of the transformer 49 is connected between the output of the high voltage power supply 31 and the hi-side of the DUT station 27. Because of the commonality of the high frequency generator in the HP4349B, only one booster requires a total of four channels of the HP4349B and the four inspection sites they serve. The internal circuitry of the HP4349B does not need to change anything.

As such, the HP4349B (Measure 1) performs its inspection protocol or "contact inspection", and also the first winding 43 of the transformer 49 gains energy by the 500 KHz voltage. The transformer 49 has a ratio of the first winding 43 to the second winding 51 between about 1: 2.5 and about 1: 3, preferably having the latter, and the first exiting the transformer 49. The second voltage is opposite to that of the first transformer 3. The second winding 51 is inserted in series with the source DC voltage from the power supply 31 and is thus applied to the "high" side of the DUT at an amplitude that would have been at least three times, and the "high" side of the DUT is connected to the inspection station ( It was only connected to the "real" ground in the configuration as shown in Figure 1 without the DUT belonging to 27). As such, the second winding 51 of the transformer 49 is given a 500 KHz voltage in series with the chip of the DUT test station 27, which is approximately three times the voltage applied to the second winding 9 of the first transformer 3. And because the two voltages are added, the voltage imparted in series with the DUT is about four times greater than that provided by the prior art circuit shown in FIG. As such, using the present invention, the sensitivity of a high resistance meter such as the HP4349B is increased by approximately four factors to the capacitance value of the DUT.

It can be seen that the booster device 45 is not only a transformer but also an amplifier as shown. Any combination of voltage and current amounts must be considered, and the signal booster is within the spirit of the present invention.

Although the invention has been described with reference to specific embodiments, those skilled in the art will be able to make various modifications to the embodiments of the invention described above without departing from the true spirit and scope of the invention. It is meant that all combinations of elements and steps that perform substantially the same function and the same method to achieve substantially the same result are within the spirit of the invention.

The present invention as described above has the following effects.

When the second or third inspection of the inspection instrument is carried out by detection of the presence of the element in the inspection station and by a high frequency signal superimposed through the device under test (DUT), it is important to inspect the electronic elements for the critical parameters of the electronic elements. It is possible to increase the minimum sensitivity of the second or third inspection of the inspection instrument having. Therefore, in the present invention, the inspection station determines the presence of the DUT before the high resistance leak test is performed. The present invention also includes an apparatus and method using the same for verifying that the test circuit will be the value of the capacitor of the inspection station, which is disclosed on the ceramic chip capacitor and what is written in, to perform the electric leakage test. End the electronic inspection of the leakage of electricity to increase the usefulness of the inspection machine of other capacitors by reducing the time required to increase the operation time, and increase the throughput of the ceramic chip capacitors of the device handler to reduce its operation time, and thus the cost of producing high quality ceramic chip capacitors. Reduces the cost of ceramic chip capacitors by increasing the efficiency of the capacitor inspection machine, and increases the ceramic capacitor inspection machine performance to test for the presence of capacitors with a capacitance of 2.0 pF or less. character It can reduce the expenditure.

Claims (12)

In order to check for the presence of electronic components at the Inspection Bureau before starting the inspection procedure, a) a signal booster having an input and an output operably aligned with the inspection device for increasing the alternating signal coming from the inspection device in multiples of one, b) connect the input of the signal booster between the inspection device and the signal output of the inspection station to place the measuring electronic component, c) connecting said output of said signal booster between an independent direct current power supply and said test station to increase in parallel the signal of said test program for measuring the capacitance of electronic components within the sensitivity range of said test meter. Sensitivity increasing device of inspection device. The method of claim 1, And the signal booster is a transformer. The method of claim 1, And the signal booster is an amplifier. The method of claim 1, The signal booster is a transformer having a first to second turns ratio of about 1.25 to about 2.25. To check for the presence of multilayer ceramic chip capacitors at the inspection station before the start of the inspection procedure, a) a signal booster having an input and an output operably aligned with the inspection device for increasing the alternating signal coming from the inspection device by a multiple of one, b) connect the input of the signal booster between the inspection device and the signal output of the inspection station to place the multilayer ceramic chip capacitor for measurement, c) connecting the output of the signal booster between an independent DC power supply and its test station to increase in parallel the signal of the test program which causes the capacitance of the multilayer ceramic chip capacitor to be measured within the sensitivity range of the test meter. Sensitivity increasing device of the high resistance test device, characterized in that. The method of claim 5, The signal booster is a sensitivity increasing device of the high resistance test device, characterized in that the transformer. The method of claim 5, The signal booster is a sensitivity increasing device of the high resistance test device, characterized in that the amplifier. The method of claim 5, The signal booster is a transformer having a first to second turns ratio of about 1.25 to about 2.25. To measure the current leakage of an electronic component in an inspection device comprising a protocol for inspecting the presence of the electronic component at the inspection station prior to measuring the leakage current, a) capturing a portion of the test protocol signal and passing the signal through an input of a signal booster; b) extracting said increment signal from the output of said signal booster; c) returning the incremental signal from the output of the signal booster to the inspection apparatus via the inspection station to provide a measurement signal of the electronic component in the station atmosphere for measurement (DUT-present) or if the electrical component is measured ( Providing a non-measurement signal if there is no station in the station atmosphere. The method of claim 9, And said increase signal is a multiple of at least three of the protocol test signal. The method of claim 9, The signal booster is a transformer and the step of passing the signal through the input of the signal booster passes the signal through the first winding of the transformer and the step of extracting the incremental signal from the output of the signal booster comprises the transformer Extracting the increase signal from the second winding of the method. The method of claim 9, The signal booster is an amplifier having an input and an output, wherein the step of passing the signal through the input of the signal booster passes the signal through the input of the amplifier and extracts the incremental signal from the output of the signal booster. And the step of extracting the increase signal from the output of the amplifier.