KR100352772B1 - Device for enhancing contact checking - Google Patents

Abstract

A sensitivity increasing device that increases the sensitivity of the inspection device to check the presence of measurement electronic components, such as small ceramic chip capacitors, on the test bench prior to beginning the inspection procedure, increases the AC signal from the inspection device in multiples of one. A signal booster having an input and an output arranged to be operable with an inspection device for connecting the signal booster between the input of the signal device and the signal output of the test table to position the measuring electronic component. Connecting the output of the signal booster between an independent dc power supply and the test bench in order to amplify the signal of the test program in a multiple that allows the capacity of the electronic component to be measured within the sensitivity of the test apparatus. Sensitivity increase device of the inspection device characterized in that.

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 is directed to devices that improve the performance of high-resistance electrical measuring instruments, such as Mercy Packard 4349B, and devices that increase the sensitivity of such instruments in the field of "Parts Present" below the minimum limit 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 0.02O × 0.020 × 0.040 inch and exhibiting capacities below 1 picofarad (pF), a small DC leakage current is generated through the portion. It is known that a limited parallel capacitance exists. 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 a Hewlett Packard model 4349B has been used.

In the ceramic capacitor (chip) industry, a 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 handlers check the capacitor terminals (current limiting power supply on one side and the HP 4349B or the other side) for DC leakage testing. To an inspection instrument such as a high resistance / low current measurement device. Before and after the leak test, the measuring instrument performs a test protocol, "component present" or "contact test" to verify the presence of the capacitors at the test table where both sides are properly connected to the test circuit. This protocol is intended to allow the parts to be properly connected in the inspection circuit at the inspection table since parts with high leakage characteristics can be classified as "good" parts.

In the case of BP 4349B, triax cable, and the 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 and passes the 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 outer shield of the Triax 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 with the same amplitude to the internal inductor of the triax cable. 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 the part present at the inspection table, these currents will not be equal and the presence of a properly connected part will be recognized by 4349B. If a "NO PART PRESENT" classification has been performed, this classification requires re-inspection of any part that was present on the inspection table and takes precedence over any classification derived from the leakage current inspection.

The drawback of this prior art practice is that parts with a capacity of less than 2 pF are often undetected, even if proper connections are made at the inspection table.

The present invention is a device and method of using the device in which the HP4349B determines whether a part is present and whether good contact is made, even if the part has a capacity as low as 0.75 pF at the inspection station. For this device, the device 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 triax 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, which in some way eliminates the "parts present" in the HP-4349B without internal modification of this possessor. "The sensitivity of the detection circuit and the amplitude of this signal can be increased.

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

Accordingly, a primary object of the present invention is to provide a means for determining the presence of a DUT at a test bench before a high resistance leak test is performed. Another object of the invention includes an apparatus and method using the same for verifying that the test circuit will be the value of the capacitor of the test stand, which is disclosed on the ceramic chip capacitor and no matter what value is written in order to perform an electrical leak test. Means for completing the electronic inspection of electrical leakage to reduce the time it takes to increase the usefulness of the inspection machine for other capacitors, and to increase the throughput of the ceramic chip capacitors of the element 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 capacity of 2.0 pF or less. Increase ceramic capacitor inspection machine performance By a means to reduce capital outlay 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 table

29 signal line 31 high voltage power supply

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

41: second triax 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 triax 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. Because of the amplitude of the signals generated from the second windings 7, 9, the same, and because the inner guard shield 21 has a low capacitance at ground at its outer end, the amplitude of the signal input to the high frequency measurement group 15 is It can be assumed that it is directly proportional to the capacity of the active inner conductor 19 at its outer end to ground.

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

The right side of the DUT test table 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 an actual output impedance of the power supply 31. FIG. 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 test bench 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 test bench 27 is empty so the digitized output of the high resistance meter 1 obtained is stored in memory. During the "Part Presence" inspection, this value is then extracted from the digitized values obtained when the part is speculatively placed on the bench 27 to obtain an assessment of proper contact with its presence on the bench 27. This method, during the compensation cycle, if the value of the stray capacitance 37 is high, such as 10 pF, compared to that of the DUT of the test table 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 stand 27 such that its DC leakage current passes through the active internal conductor 19 of the first triax 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 triax 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 triax 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 test stand 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 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 with the latter, and the second coming out of the transformer 49. The 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 test stand ( 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 voltage of 500 KHz in series with the chip of the DUT test stand 27 which is about three times the voltage applied to the second winding 9 of the first transformer 3. And the two voltages are added, so that the voltage applied 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 performed by detecting the presence of the element in the inspection table and by a high frequency signal superimposed through the device under test (DUT), it has an important function of inspecting the electronic elements for the important parameters of the electronic elements. It is possible to increase the minimum sensitivity of the second or third inspection of the inspection instrument. Therefore, in the present invention, the presence of the DUT is determined at the test bench before the high resistance leak test is performed. In addition, the present invention includes an apparatus and a method using the same for verifying that the test circuit will be the value of the capacitor of the test stand, which is disclosed on the ceramic chip capacitor and written in whatever value is written, 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 a good quality ceramic chip capacitors. Reduce the cost of ceramic chip capacitors by increasing the efficiency of the capacitor inspection machine, and increase the ceramic capacitor inspection machine performance to test for the presence of capacitors with a capacity of 2.0 pF or less. Capital expenditure Can be reduced.

Claims (12)

In a sensitivity increasing device for increasing the sensitivity of the inspection apparatus to check the presence of the measuring electronic components on the inspection table before starting the inspection procedure, A signal booster having an input and an output operably aligned with the inspection device for amplifying the alternating signal from the inspection device in multiples of one, The sensitivity increasing device connects the input of the signal booster between the test device and the signal output of the test table to place the measuring electronic component, The sensitivity increasing device uses an independent direct current power supply and the test table for outputting the signal booster's output to amplify the signal of the test program in multiples to enable measuring the capacitance of the electronic component within the test device's sensitivity range. Sensitivity increase device of the inspection device characterized in that the connection. 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, Wherein said signal booster is a transformer having a turns ratio of about 1.25 to about 2.25 between the first and second windings. In a sensitivity increasing device for increasing the sensitivity of a high resistance test device to check the presence of a multi-layer ceramic chip capacitor on the test bench before starting the test procedure, A signal booster having inputs and outputs arranged to be operable with the inspection device for amplifying the alternating current signal from the inspection device in multiples of one, The sensitivity increasing device connects the input of the signal booster between the test device and the signal output of the test table to place the multilayer ceramic chip capacitor, The sensitivity increasing device further comprises an independent direct current power supply and the output of the signal booster to amplify the signal of the test program in multiples to enable the capacitance of the multilayer ceramic chip capacitor to be measured within the sensitivity range of the test device. Sensitivity increase device of the high resistance test device, characterized in that connected between the test table. 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, Wherein said signal booster is a transformer having a turns ratio of about 1.25 to about 2.25 between the first and second windings. In the sensitivity improvement method for improving the sensitivity of the inspection apparatus for measuring the current leakage of the electronic component, including a protocol for inspecting the presence of the electronic component on the inspection table before 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) passing the amplified signal through the test bench from the output of the signal booster to the test apparatus, providing a measurement signal of the electronic component when the electronic component is on the test bench (DUT-present) ready for measurement And if the electronic component is not on the inspection table prepared for measurement (no DUT), not providing a measurement signal of the electronic component. The method of claim 9, And wherein said amplified signal is a multiple of at least three of the protocol test signal. The method of claim 9, The signal booster is a transformer, Said step (a) of passing said signal through an input of a signal booster includes passing said signal through a first winding of said transformer, And extracting the amplified signal from the output of the signal booster comprises extracting the amplified signal from the second winding of the transformer. The method of claim 9, The signal booster is an amplifier having an input and an output, The step (a) of passing the signal through the input of a signal booster includes passing the signal through the input of the amplifier, And extracting the amplified signal from the output of the signal booster comprises extracting the amplified signal from the output of the amplifier.