JPH02103479A - Method for testing withstand voltage against electrostatic discharge - Google Patents

Abstract

PURPOSE:To shorten the test time and reduce the number of working processes by comparing a time waveform of an applying pulse and a reference waveform at a plurality of points of said waveform by a microcomputer thereby to automatize switching of a switch and a measuring method. CONSTITUTION:A test sample 2 is connected to a measuring terminal of a measuring instrument 1 which measures withstand voltage against electrostatic fault, thereby to detect a waveform by a voltage/time waveform detector 3. In comparing a waveform at a normal time with a waveform at an abnormal time when an impedance is changed to an electrostatic discharge destruction, the time differs to the same voltage. Therefore, if the voltage/time characteristic at an initial value is different from that at the measuring time, it is judged that the sample 2 is broken to the source voltage. The time difference is detected by a microcomputer 4 to determine the withstand voltage against electrostatic discharge, so that a mercury relay switch 6 of the measuring instrument 1 is controlled to stop the measurement. The voltage/time characteristic at the initial value to the source voltage E for each stage is stored in an input/output device 5 so as to be compared with the voltage/time characteristic at the measuring stage.

Description

[Detailed Description of the Invention] [Summary] Regarding a withstand voltage test method during electrostatic discharge of electronic components, the purpose of this method is to automatically determine whether or not a sample is destroyed based on a pulse waveform each time a voltage is applied. A voltage/time waveform detector is connected to both ends of the sample connected to the device, and a microcomputer is used to compare the time waveform of the applied pulse and the reference waveform at multiple points on the waveform, and to store the initial measurement value for each voltage application. It is equipped with an input/output device, a function to stop the operation of the electrostatic discharge withstanding voltage measuring device when sample destruction is detected, and a function to control the power supply voltage step by step. The time waveform of the pulse is monitored every time, and a change in the waveform with respect to an initial value is detected to determine whether or not the sample is destroyed.

[Industrial application field]

TECHNICAL FIELD The present invention relates to a withstand voltage test method for electrostatic discharge of electronic components.

Electrostatic discharge voltage measuring instruments have traditionally been used to take samples of electronic components and conduct voltage breakdown tests. The electrostatic discharge withstand voltage measuring device is a measuring device specified in accordance with the MIL standard, which charges an electrolytic capacitor with a high power supply voltage.
The charged voltage of the capacitor is discharged to the sample by the switch operation of the water relay, and the sample is subjected to a withstand voltage test to calculate the maximum non-destructive voltage, that is, the withstand voltage of the sample.

Electrostatic discharge withstand voltage is ESD withstand voltage (Electro Sta.
ticDischarge 5 sensitivity)
It is called ``electronic component'' and must be measured from time to time to define the characteristics of electronic components. For this reason, ESD withstand voltage tests are conducted by extracting samples of electronic components and repeatedly applying high-voltage pulses to them. The present invention provides a method for easily performing the ESD withstand voltage test.

[Conventional technology]

A conventional ESD withstand voltage test method is shown in FIG. In the figure, 1 is an ESD withstand voltage measuring device, 2 is a test sample, 8 is a voltage/current characteristic measuring device (braun tube), and 9 is a changeover switch.

ESD withstand voltage withstand voltage measuring device This is a measuring device specified by the MIL standard, which is commercially available, and consists of a variable high voltage power supply E, an electrolytic capacitor C, a water root relay switch S, and a load circuit resistor R.
The high voltage charged in the electrolytic capacitor C is applied to the test load sample 2 by charging the electrolytic capacitor C with a continuously variable high voltage power supply IE and momentarily turning the mercury relay switch S on and off for the number of measurements. .

A changeover switch 9 is provided in the load circuit in series with the resistor R.
After the application is completed, the sample 2 is connected to the voltage/current characteristic measuring device 8 by manual switching. Voltage/current characteristics measuring instrument 8
is a curve tracer (such as a cathode ray tube) that displays the characteristics of output current with respect to input voltage. FIG. 6 shows an example of voltage/current detection characteristics. The figure shows an example of curve characteristics when using a transistor, diode, IC, etc. as a sample. If sample 2 is not destroyed, this curve will follow the same trajectory as the solid line before application. The test is repeated by changing the power supply voltage E step by step, and when this curve changes from before voltage application as indicated by the dotted line, it is determined that sample 2 has been destroyed. For example, the dotted line ■ indicates short-circuit failure, the dotted line ■ indicates deterioration failure, and the dotted line ■ indicates open failure.

[Problem to be solved by the invention]

Therefore, in the conventional ESD withstand voltage measurement method, both the voltage E and the changeover switch 9 are manually changed.
Since the judgment using the voltage/current characteristic measuring device 8 is also performed manually,
It took a lot of work and time.

An object of the present invention is to automate switch switching and measurement methods by using a microcomputer, thereby shortening test time and reducing the number of work steps.

[Means to solve the problem]

The method for testing electrostatic discharge withstand voltage according to the present invention is shown in FIG. In the figure, 1 is an electrostatic discharge voltage (ESD) measuring device;
2 is a test sample connected to the measurement terminal of the electrostatic discharge withstand voltage measuring device, 3 is a voltage/time waveform detector connected to both ends of the test sample, and 4 is a waveform of the time waveform of the applied pulse and the reference waveform. 5 is an input/output device for storing the initial measurement value for each voltage application; 6 is for controlling the mercury relay switch S of the electrostatic discharge voltage measuring device 1 when destruction of the sample is detected; Function 7 indicates a function of controlling the power supply voltage E of the electrostatic discharge withstand voltage measuring device 1 in stages.

The function 6 of controlling the mercury relay switch S and the function 7 of controlling the power supply voltage E in stages of the electrostatic discharge withstand voltage measuring device 1 are automatically performed under the control of the microcomputer 4. Further, the voltage/time waveform detector 3 is a device that detects ESD damage using an oscilloscope or a cathode ray tube. The input/output device 5 is a database for storing waveforms, and is composed of a ROM, an IC, a magnetic disk, or the like.

[Effect]

The test sample 2 is connected to the measurement terminal of the electrostatic discharge withstand voltage measuring device 1, and the voltage/time waveform detector 3 detects the waveform.

FIG. 2 shows an example of the waveform monitor of the voltage/time waveform detector 3. In the figure, if ■ is a normal waveform and ■ is a waveform whose impedance has changed due to ESD destruction, when comparing the normal waveform (■) and the abnormal waveform (■), the times for the same voltage will be different. Therefore, if the voltage/time characteristic at the initial value is different from the voltage/time characteristic at the time of measurement, it is determined that sample 2 is destroyed at that power supply voltage. This time difference is calculated by the microcomputer 4.
The electrostatic discharge withstand voltage is detected and the ESD withstand voltage is determined, and the mercury relay switch 6 of the electrostatic discharge withstand voltage measuring device 1 is controlled to stop the measurement.

Note that the voltage/time characteristics of the initial values for the power supply voltage at each stage are stored in the input/output device 5, and compared with the voltage/time characteristics at the measurement stage.

〔Example〕

An embodiment of the present invention will be described with reference to the principle configuration diagram shown in FIG.

In the figure, electricity? The R voltage E is controlled in stages by a control function 7 from the microcomputer 4. The power supply voltage is 100V boosted and transformed by a transformer and sent out. The mercury relay switch S is automatically switched to the electrolytic capacitor C by the control function 6 from the microcomputer 4.
Charging and discharging are performed sequentially.

Next, the voltage/time waveform detector 3 measures voltage and time by setting four criteria for voltage.

FIG. 3 shows an example of reference points for determining applied voltage. In the figure, the power supply voltage Vp is 100OV, and the judgment reference point is 1
00χ and each rising and falling 90χ, 5(1
%, 10χ, total 7 points, and calculate the time Tp for the reference voltage νp, the voltage ν,. , vso, v,.

Voltage/time characteristics at time and initial value and above 7
By comparing points, changes in voltage/time characteristics are detected.

Next, FIG. 4 shows a control flowchart of the microcomputer in this embodiment. In the figure, (11 power supply voltage E is set to voltage Vp by stepwise control function 7).

(2) Start the electrostatic discharge withstand voltage test using the mercury switch control function 6.

(3) Measured value Tp' (
7 points) is detected and compared with the initial value 'rp (7 points) stored in the input/output device 6 in advance.

(4) If the measurement results are within the error or the same, continue the test. (Repeat the above test 5 times) (5) Test 0
If so, the next voltage vp1 is set and started.

(6) By repeating the above operation, a test is performed by sequentially setting higher power supply voltages.

(7) Set initial value 7p1 and measurement result 7 during measurement
p1'' is different, or if it is determined that it is outside the specified range by comparison at other determination reference points, the previous set value ν
Determine p as the electrostatic discharge withstand voltage.

(8) Stop the electrostatic discharge withstand voltage test using the mercury switch control function 6.

〔Effect of the invention〕

According to the present invention, when performing an ESD withstand voltage test on an electronic component, there is no need to change a switch or directly measure the characteristics of the component using a measuring device, unlike in the past, and the number of work steps and time can be reduced. Furthermore, even in the case of samples that are sensitive to current, there is no need to pass current through the sample to confirm the characteristics (there is no risk of accidentally degrading the sample, and accurate withstand voltage values can be measured).

[Brief explanation of drawings]

Fig. 1 is a diagram of the principle configuration of the present invention, Fig. 2 is a voltage/time waveform detection characteristic diagram, Fig. 3 is an applied voltage judgment reference point of the embodiment, Fig. 4 is a control flowchart of the embodiment, and Fig. 5 is a diagram of the voltage/time waveform detection characteristics. FIG. 6 shows a measurement configuration diagram of a conventional example, and a voltage/current characteristic detection measurement diagram. In the figure, 1 is an electrostatic discharge withstand voltage measuring device, 2 is a test sample, 3 is a voltage/time waveform detector, 4 is a microcomputer, 5 is an input/output device, 6 is a mercury relay switch control function, and 7 is a power supply voltage control 8 is a voltage/current characteristic measuring device, and 9 is a changeover switch. Note that (1) to (8) indicate step numbers of the control flowchart. Control flowchart of the embodiment

Claims (1)

[Claims] A voltage/time waveform detector (3) is connected to both ends of a test sample (2) connected to an electrostatic discharge voltage measuring device (1) in a voltage test method for electrostatic discharge of electronic components. A microcomputer (4) that compares the time waveform of the applied pulse with the reference waveform at multiple points on the waveform, an input/output device (5) that stores the initial measurement value for each voltage application, and a device that detects sample destruction. Sometimes the above electrostatic discharge withstand voltage measuring device (
It is equipped with a function (6) to stop the operation of 1) and a function (7) to control the power supply voltage in stages, and under the control of the microcomputer (4), the time waveform of the pulse is changed every time the voltage is applied. 1. A test method for electrostatic discharge withstand voltage, which comprises monitoring and detecting a change in waveform with respect to an initial value to determine whether or not the sample is destroyed.