JPH0438302Y2 - - Google Patents

Description

[Detailed explanation of the invention] (a) Industrial application field This invention is a testing device for integrated circuits (hereinafter referred to as IC), specifically for measuring the withstand strength of ICs against surge voltages such as electrostatic discharge. Regarding test equipment.

(b) Conventional technology Conventionally, various standards (MIL-STD-883C, MIL-STD-883C, MIL-STD-
1686, MIL-M38510, BS, EIAJ-IC-121), the capacitor charging method shown in Figure 4 is adopted. That is, the configuration shown in FIG.
By switching the charge/discharge switch 3, the electric charge charged in the capacitor 2 via the resistor 4 is discharged, and a short period (20 waves) is generated between the predetermined terminals of the IC5.
This applies a surge voltage of 50ns).

Such IC electrostatic discharge test equipment has recently been commercially available from some manufacturers, but it is difficult to connect the electrical connection between the surge voltage generation part and the IC, that is, the first part for surge voltage application in Figure 4. Connections between the terminal 6 and the second terminal 7 and each external terminal 8 of the IC 5 are made manually, and it is very time consuming to test various combinations of IC terminal connections.

In view of the above points, the present invention is a test in which connections to IC terminals are automatically switched using an electrical switch, and through such a switch, surge voltage is applied, voltage-current characteristics are measured, and IC quality judgment is automatically performed. We have already proposed a device (Japanese Patent Application No. 59-217006).

(c) Problems that the invention aims to solve As mentioned above, it is practical to use a relay switch as an electrical switch for automatically switching the connection to an IC terminal, but the stray capacitance of the relay switch is recognized as a unique problem.

In FIG. 5, such a problem is explained more specifically. A pair of first and second selection switches 10, 11 are arranged corresponding to each external terminal 8a, 8b, . . . of the IC 5. Each of these selection switches is of the relay switch type and consists of a normally open relay contact 12 and a relay coil 13 for energizing the contact into the open state. One end of the relay contact 12 belonging to each first selection switch 10 is commonly connected to the first wiring 14, while one end of the contact 12 belonging to each second selection switch 11 is commonly connected to the second wiring 15. The other ends of the relay contacts 12 belonging to each identical pair of first and second selection switches 10 and 11 are connected to corresponding external terminals of the IC 5. One end of all the relay coils 13 is connected to the third wiring 16. first and second wiring 14,
15 are connected to the first and second surge voltage application terminals 6 and 7 (see FIG. 4), respectively, and the third wiring 16 is grounded. This ground is electrically connected to the ground line of the surge voltage application section that connects to the second terminal 7, but in normal actual wiring, each coil 13 is connected to the third wiring 16 that is separate from the second wiring 15. It is tied and guided to the ground above.

In the above device, for example, in order to apply a surge voltage between the external terminals 8a and 8b of the IC 5, the capacitor 2 in the circuit of FIG. 4 is charged, and the first selection switch 10 corresponding to the external terminal 8a is Relay coil 12 and other external terminal 8b
The relay coils 12 of the second selection switch 11 corresponding to the first and second selection switches 11 are energized, respectively, and the switch 3 of the circuit shown in FIG. 4 is switched to the discharge side.

However, each selection switch has relay coil 1.
3 and the relay contact 12.
Now, if the above stray capacitance in the first selection switch 10 is C, then from the surge voltage application terminals 6 and 7
When looking at the IC5 side, as shown in the equivalent circuit of FIG. 6, the total stray capacitance ΣCI of each first selection switch 10 is input in parallel with the internal impedance Z appearing between the external terminals 8a and 8b. Become.

Typically, the value of CI is between 2.5 and 5PF, so IC5
If the number of external terminals is 40, ΣCI will be 100 to 200 pF, but such a large stray capacitance is caused by external terminals 6, 6,
The rise of the surge voltage that is actually applied during the period 7 is also delayed (about 10 times), and the peak value is also greatly reduced (about half), which has an adverse effect on the surge voltage application test.

Stray capacitance of second selection switch 11 (referred to as C2)
Considering the effect of , other external terminals that are not currently being measured will be connected to ground through C2. However, since the impedance of this ground path is relatively large, the effect of C2 is hardly a problem compared to the effect of ΣCI mentioned above, unless high measurement accuracy is required.

The present invention particularly aims to eliminate the influence of ΣCI mentioned above.

(d) Means for solving the problem The device of the present invention is a device that connects a surge voltage section to a plurality of external terminals of an integrated circuit through a selection switch arranged corresponding to each of the external terminals. ,
The selection switch is comprised of a relay consisting of a relay contact, a relay coil, and a guard body that electrostatically isolates them from each other, and the guard body is connected to the ground line of the surge voltage section. .

(e) Effect According to the present invention, the influence of the stray capacitance mentioned above is substantially eliminated due to the presence of the guard body.

(F) Embodiment FIG. 1 shows an embodiment, and the same parts as in FIG. 5 are given the same numbers. As a feature of this embodiment, the first and second selection switches 10 and 11 are all
It has a configuration in which a guard body 20 is inserted between the relay contact 12 and the relay coil 13, and each guard body 20
and one end of the relay coil 12 is connected to the second wiring 1 in common.
5 and is connected to the ground side terminal 7 of the surge voltage application section.

FIG. 2 shows details of such a switch, and a guard body 20 made of a metal cylinder such as brass is installed between a glass tube 30 that seals the relay contact 12 and a relay coil 13 surrounding the tube. A tube 30 is housed within the guard body. Therefore, the guard body 20 protects the relay contacts 12 and the relay coil 13.
are electrostatically isolated from each other, and the stray capacitance existing in the switch is the stray capacitance Cc between the relay contact 12 and the guard body 20, as shown in the equivalent circuit of FIG.
Stray capacitance between guard body 20 and relay coil 13
It is CL.

In the device of this embodiment, when looking at the IC 5 side from the surge voltage application terminals 6 and 7, there is a total sum ΣCc of the stray capacitances Cc of each first selection switch 10.
However, in the above relay switch with guard body, the value of Cc is very small at 0.3 to 0.4PF, so even if the number of external terminals of IC5 is 40, the total sum ΣCc is
20PF or less, and such a value does not cause a large delay in surge voltage application or a large drop in the peak value as in the conventional surge voltage application test.
No substantial adverse effects.

The third wiring 16 shown in FIG. 5 does not exist in this embodiment, and the guard body 20 of each selection switch and the relay coil 13 of each selection switch are connected to the second wiring 15.
It is directly connected to This connects the guard body 20 and relay coil 13 to the second wiring 15 at the furthest possible distance.
and earth connection. With such wiring, the stray capacitance of the second selection switch 11 is almost completely eliminated, and therefore the influence of the stray capacitance _C2 of the second selection switch described in connection with FIG. 5 does not exist at all.

(g) Effects of the invention According to the invention, when selectively applying a surge voltage to each terminal of an IC using a relay switch in an IC surge voltage application test device,
The influence of the stray capacitance of the relay switch, which has been a problem in the past, ie, the adverse effect on the rise and peak value of the applied surge voltage, is substantially eliminated, and highly accurate tests can be performed.

[Brief explanation of the drawing]

1 to 3 show an embodiment of the present invention; FIG. 1 is a circuit diagram of a main part, FIG. 2 is a sectional view of a selection switch, and FIG. 3 is an equivalent circuit diagram of the same switch. FIG. 4 is a standard circuit for a surge voltage application test, and FIGS. 5 and 6 are conventional circuit diagrams. 5... Integrated circuit, 6, 7... Surge voltage application terminal, 10, 11... First and second selection switch, 1
2... Relay contact, 13... Relay coil, 20
...Guard body.

Claims (1)

[Scope of utility model registration request] A device that connects a surge voltage section to a plurality of external terminals of an integrated circuit through a selection switch arranged corresponding to each of the external terminals, the selection switch connects a relay contact and a relay coil, and connects both of them with an electrostatic charge. 1. A testing device for an integrated circuit, comprising a relay comprising a guard body and a guard body that are electrically isolated from each other, and the guard body is connected to a ground line of the surge voltage section.