JPH0652290B2 - Method for detecting incorrect insertion of IC component terminal on mounting board - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for detecting erroneous insertion of each terminal of an IC component mounted on a printed circuit board.

2. Description of the Related Art In recent years, a printed circuit board on which an IC component is mounted is suitable for miniaturization and mass production, so that it has been adopted in various electronic devices and the demand has increased remarkably. However, it is necessary to strictly inspect the mounting state of the IC component when using it. This is because if not properly mounted, the IC device is not only damaged but also the entire device is destroyed. Therefore, after each terminal of the IC component is inserted into the lead hole of the printed board and soldered and mounted, it is inspected whether the inserted state is normal or incorrect. However, in general, IC parts are shaped so that the front side and the back side thereof can be clearly distinguished, and the power supply terminal and the ground terminal are in symmetrical positions. Therefore, normally, it suffices to inspect whether the power supply terminal and the ground terminal are reversely inserted.

For example, when using an in-circuit tester, I
The current path created by the input clamp diode attached to the TTL circuit included in the C component, and the protection diode such as the substrate diode between the collector of the transistor and the ground is used to connect the probe to the power supply terminal of the IC component or ground. A constant current source is applied between the terminals and the input or output terminals to pass a current, and the voltage (potential difference) between the terminals is measured to inspect whether the insertion is normal or incorrect. That is, the voltage between terminals at the time of normal insertion is first measured and used as a reference, and the reference voltage is compared with the voltage measured by the corresponding test to detect erroneous insertion from the difference between the two voltages. However, in the case of an IC component mounted on a printed circuit board, another circuit connected to the terminal of the IC component influences the measurement, and there is a slight difference in the voltage value between normal insertion and incorrect insertion, for example, only a few mV. Often does not occur. Therefore, even if the in-circuit tester is used, it is not easy to detect the incorrect terminal insertion of the IC component on the mounting board.

Therefore, the present applicant previously filed a patent application No. 32759 in 1987.
No. 8 is an IC component having a power supply terminal, a ground terminal, an input terminal, and an output terminal mounted on a printed circuit board,
The sum of the two power supply voltages is larger than the rising voltage of the diode included in the IC component, but each power supply voltage alone is smaller than the rising voltage. The first power supply and the second power supply are used, and the first power supply voltage is used as the power supply terminal. Apply the second power supply voltage to the power supply terminal or ground terminal and the input terminal or output terminal via the ammeter, and detect the incorrect insertion of the IC component terminal on the mounting board according to the ammeter's instruction. I showed you how to do it.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in such a method for detecting the incorrect insertion of the terminal of the IC component on the mounting board, when only one IC component 10 is mounted on the printed circuit board as shown in FIG. With the protection diode included, the indication of the ammeter 12 changes greatly during normal insertion shown in (a) and during reverse insertion shown in (b), and incorrect insertion of the terminal can be detected, but as shown in FIG. When the capacitor 14 is further mounted,
Regardless of the normal insertion shown in (a) and the reverse insertion shown in (b), since the charging current flows as a transient phenomenon in the capacitor 14, there is no clear change in the indication of the ammeter 12 and the incorrect insertion of the terminal. It may be difficult to detect. That is, when the former is normally inserted, the voltage sum of the first and second power supplies 18 and 20 larger than the rising voltage is applied to the protection diode 16 in the forward direction, so that the ammeter 12 is connected to the power supply, ground, and output terminals 22. , 24, 26, a large current flows in the direction of the arrow, while the sum of both power supply voltages is applied to the protection diode 28 in the reverse direction at the time of reverse insertion.
Only a small amount of current flows through the ground and output terminals 22, 24, 30 along the dotted line in the arrow direction. On the other hand, in the latter case, when the charging current flows in the arrow direction in the capacitor 14 as a transient phenomenon even during normal insertion, the sum of both power source voltages becomes lower than the rising voltage of the protection diode 16, and the ammeter 1
2. Only a very small current may flow in the direction of the arrow. Generally, it is rare to mount only an IC component as a single component on a printed circuit board, and a bypass capacitor such as a ceramic capacitor or an electrolytic capacitor is connected between the power supply terminal and the ground terminal.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a method for accurately detecting an incorrect terminal insertion of an IC component on a mounting board in consideration of a transient phenomenon of a capacitor. And

Means for Solving the Problems Means for achieving the above object will be described with reference to FIGS. 1 and 2 corresponding to the embodiment.

The method for detecting the incorrect insertion of the IC component terminal on the mounting board is to inspect the IC component 32 having the power supply terminal 34, the ground terminal 36, the input terminal 38, and the output terminal 40 mounted on the printed circuit board, and to detect both power supply voltages. Although the sum is larger than the rising voltage of each protection diode 44, 46, 48, 50 included in the IC component 32, the first power supply 52 and the second power supply 54 which are smaller than the rising voltage at each power supply voltage alone are used. The first power supply voltage is applied to the power supply terminal 34 and the ground terminal 36, and the second power supply voltage is supplied to the power supply terminal 3 via the ammeter 56.
4 or the ground terminal 36 and the input terminal 38 or the output terminal 40, and I on the mounting board according to the instruction of the ammeter 56.
This is for detecting the incorrect insertion of the terminal of the C component 32. At this time, the first power supply voltage is first applied to charge the mounting capacitor 42 connected to the power supply terminal 34 and the ground terminal 36 of the IC component 32, and then the second power supply voltage is applied.

Operation With the above configuration, the first power supply voltage is first applied to the power supply terminal 34 and the ground terminal 36, and the charging of the capacitor 42, which is a transient phenomenon, is completed.
No current flows through it. Then, when the second power supply voltage is applied next, the first power supply voltage that has once dropped due to the charging of the capacitor 42 is restored to the old one, and the second power supply voltage is newly added to the old power supply voltage. Therefore, only one IC component is mounted. Similar to the above case, the sum of both power supply voltages becomes larger than the rising voltage of the diode 46. Therefore, the current flowing through the ammeter 56 changes greatly between the normal insertion and the reverse insertion, and the indication of the current also greatly changes, so that the erroneous insertion of the terminal on the mounting board can be easily detected.

Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a circuit diagram showing a process of applying the method for detecting incorrect insertion of an IC component terminal on a mounting board according to the present invention to an IC component normally inserted in a printed circuit board and measuring the diode current, and FIG. 2 is the same. I the detection method was inserted back into the printed circuit board
It is a circuit diagram which shows the process which applies to C component and similarly reaches the measurement of the diode current. In the figure, 32 is a power supply terminal 34, a ground terminal 36, and an input terminal 3 mounted on a printed circuit board.
8 and an IC component having an output terminal 40, and 42 is a capacitor connected to the power supply terminal 34 and the ground terminal 36. Inside the IC component 32, as shown in FIG. 1, for the power supply, ground, and output terminals 34, 36, and 40,
Two protection diodes 44 and 46 are included as an equivalent circuit. That is, the diodes 44 and 46 are connected in series between the power supply and ground terminals 34 and 36 with their cathodes facing toward the power supply terminal side, and the intermediate point is further connected to the output terminal 40.
Connect with. Further, as shown in FIG. 2, two protection diodes 48 and 50 are included in an equivalent circuit for the power supply, ground and input terminals 34, 36 and 38. However, both diodes 48 and 50 have their cathodes connected in series between the power supply and ground terminals 34 and 36, facing the power supply terminal side, and the middle point thereof is connected to the input terminal 38. The land into which the power supply terminal 34 of the IC component 32 is normally inserted is set to the ground potential.

Each terminal 3 of the IC component 32 on such a mounting board
To inspect the insertion state of 4, 36, 38, and 40, first, the first power supply 52 is used, and as shown in FIG. 1 (a), it is connected to both the power supply and ground terminals 34 and 36 of the IC component 32. . Then, the charging current in the arrow direction flows from the first power supply 52 to the capacitor 42. The voltage of the first power supply 52 is set smaller than the rising voltage of each protection diode 44, 46.
This charging current is transient, and the charging ends after a lapse of a certain time, so that the current stops flowing thereafter. Therefore, the first power supply voltage that has once dropped is restored to the old one. next,
Using the second power supply 54, as shown in FIG. 1 (b), the ammeter 5
Power source and output terminals 34, 4 of the IC component 32 via 6
Connect to 0. The voltage of the second power supply 54 is also made smaller than the rising voltage of each protection diode 44, 46. Therefore, the protection diode 46 includes the first and second power supplies 52, 5
The voltage sum of 4 is added. The sum of such two power supply voltages is made larger than the rising voltage. For example, in the case of a silicon diode, since the rising voltage is about 0.6V, the voltage of the first power supply 52 is set to about 0.4V and the voltage of the second power supply 54 is set to about 0.2V. Then, the diode 46 rises and a large current flows in the arrow direction through the ammeter 56.
At that time, since the capacitor 42 is charged, current does not flow there, and the load on both power sources 52 and 54 is reduced, which is the same as the case where only one IC component is mounted. Therefore, when the IC component 32 is normally inserted in the printed circuit board, the ammeter 56 largely swings.

Next, also when the IC component 32 is reversely inserted in the printed circuit board, first, the first power source 52 is connected to the power source and ground terminals 34 and 36 of the IC component 32 as shown in FIG. 2 (a). Connect to. Then, the capacitor 42 is charged. Next, as shown in FIG.
Via the power supply and input terminals 36, 3 of the IC component 32
Connect to 8. Therefore, the protection diode 50 has a second
The voltage of the power supply 54 is applied, and the voltage sum of the first and second power supplies 52 and 54 is applied to the protection diode 48. But,
Since each power supply voltage alone is lower than the rising voltage of each diode 48, 50, the diode 50 does not conduct. Further, even if the sum of the two power supply voltages is made larger than the rising voltage of the diode 48, the reverse voltage is applied to the diode 48, so that the conduction does not occur. Therefore, only a small amount of current flows through the ammeter 56 along the dotted line in the direction of the arrow, and almost no vibration occurs.

In this way, the current flowing through the ammeter 56 changes greatly between the normal insertion and the reverse insertion, and the indication thereof also changes greatly, so that the incorrect insertion of the terminal can be easily detected. In the above embodiment, as shown in FIG. 3 (a), the second power source 54 is connected to the ammeter 5
It was placed near the upper right corner of the IC component 32 via 6 and was connected to the power or ground terminal and the output or input terminal in the vicinity thereof, as shown in FIGS. 3 (b), (c) and (d). As described above, they may be arranged in the vicinity of the other three corners and connected to the similar terminals in the vicinity thereof. However, in the latter connection method, the ammeter hardly swings during normal insertion, and the ammeter may swing largely during reverse insertion. After all, in either connection method, the indication of the ammeter largely changes between the normal insertion and the reverse insertion, so that the incorrect insertion of the terminal can be detected. If such a detection method is applied to an in-circuit tester, the I
The detection rate of incorrect insertion of the C component terminal is improved.

EFFECTS OF THE INVENTION According to the present invention described above, it is possible to eliminate the influence of the transient phenomenon of the capacitor mounted on the printed circuit board together with the IC component. Therefore, it is possible to accurately detect the incorrect insertion of the terminal of the IC component on the mounting board. You can Further, it is possible to accurately detect the missing state of IC parts.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a process of applying the method for detecting incorrect insertion of an IC component terminal on a mounting board according to the present invention to an IC component normally inserted in a printed circuit board and measuring the diode current, and FIG. 2 is the same. I the detection method was inserted back into the printed circuit board
It is a circuit diagram which shows the process which applies to C component and similarly reaches the measurement of the diode current. FIG. 3 is a circuit diagram showing the process of measuring the diode current by applying the same detection method according to the present invention to an IC component inserted in a printed circuit board. FIG. 4 is a circuit diagram showing the measurement of the diode current when the conventional detection method is applied to an IC component that is normally and reversely inserted in a printed circuit board. FIG. 5 is a circuit diagram showing the measurement of the diode current when the conventional detection method is applied to an IC component which is normally and reversely inserted together with a capacitor on a printed circuit board. 32 ... IC, 34, 36, 38, 40 ... Power, ground, input and output terminals, 42 ... Capacitors, 44, 46,
48, 50 ... Protection diodes, 52, 54 ... First and second
Each power supply, 56 ... Ammeter

Claims (1)

[Claims] 1. An IC component having a power supply terminal, a ground terminal, an input terminal, and an output terminal mounted on a printed circuit board,
The sum of both power supply voltages is larger than the rising voltage of the protection diode included in the IC component, but each power supply voltage alone is smaller than the rising voltage. And the ground terminal,
A method of applying a second power supply voltage to a power supply terminal or a ground terminal and an input terminal or an output terminal via an ammeter, and detecting an erroneous insertion of an IC component terminal on a mounting board according to an instruction of the ammeter. Detection of erroneous insertion of IC component terminals on a mounting board, characterized by first applying a power supply voltage to charge a mounting capacitor connected to both power supply and ground terminals of the IC component and then applying a second power supply voltage Method.