JPH0652289B2 - Method for detecting incorrect IC terminal insertion - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for detecting erroneous insertion of each terminal of an IC component inserted in a lead hole of 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, in the case of using an in-circuit tester, a current path created by an input clamp diode attached to a TTL circuit included in an IC component or a substrate diode between the collector of a transistor and ground is used to connect a probe. Therefore, as shown in at least one of (a), (b), (c) and (d) in FIG. 15, the power supply terminal 12 or the ground terminal 1 of the IC component 10 is
4 and the input terminal 16 or the output terminal 18 between the constant current source 2
0 is applied to apply a constant current, and the voltage (potential difference) between its terminals
To check whether the insertion is correct 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. It can be said that erroneous insertion is more likely to be detected as the number of voltages measured by the inspection corresponding to each reference voltage increases.

Problems to be Solved by the Invention However, there is a problem in such a method for detecting incorrect terminal insertion of an IC component. This is because, in the case of an IC component mounted on a printed circuit board, other circuits connected to the terminals of the IC component have an influence, and a slight difference, for example, only a few mV, occurs in the voltage values of normal insertion and incorrect insertion. I often don't. Therefore, even if the in-circuit tester is used, it is not easy to detect the incorrect terminal insertion of the IC component.

The present invention has been made in view of such a conventional problem, and provides a method for accurately detecting an erroneous insertion of a terminal of an IC component mounted on a printed circuit board by reducing the influence of a peripheral circuit. The purpose is to

Means for Solving the Problems Means for achieving the above object will be described below with reference to FIG. 1 corresponding to the embodiment.

This method for detecting incorrect insertion of terminals of an IC component is to inspect an IC component 22 having a power supply terminal 24, a ground terminal 26, an input terminal 28, and an output terminal 30 mounted on a printed circuit board, and the sum of the two power supply voltages is the IC component. The first power source 32 and the second power source 34 are used, and the ammeter 36 is used, which is higher than the rising voltage of the diode included in 22, but smaller than the rising voltage for each power supply voltage alone. The voltage is applied to the power supply terminal 24 and the ground terminal 26, and the second power supply voltage is applied to the power supply terminal 24 or the ground terminal 26 and the input terminal 28 or the output terminal 30 via the ammeter 36, and the instruction of the ammeter 36 is given. To the printed circuit board
The erroneous insertion of the terminal of the C component 22 is detected.

Operation The above means operates as follows.

When the first power supply voltage is applied to the power supply terminal 24 and the ground terminal 26 and the second power supply voltage is applied to the power supply terminal 24 or the ground terminal 26 and the input terminal 28 or the output terminal 30 via the ammeter 36, both power supplies are supplied. The sum of the voltages is higher than the rising voltage of the diode included in the IC component 22, but is smaller than the rising voltage of each power supply voltage alone, so the influence of the surrounding circuit is reduced, and the ammeter is used according to the forward and reverse characteristics of the diode. The value of the current flowing through 36 changes greatly. As a result, the directionality of the IC component 22 becomes clear, and erroneous terminal insertion can be detected.

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

FIG. 1 is a diagram showing an example of each circuit to which the method for detecting incorrect insertion of an IC component terminal according to the present invention is applied. In the figure, 22 is an IC component having a power supply terminal 24, a ground terminal 26, an input terminal 28, and an output terminal 30 all mounted on a printed circuit board.
These IC parts 22 include an equivalent circuit as shown in FIG. 2 or FIG. The open collector type TTL shown in FIG. 2 and the CMOS inverter shown in FIG. 3 are both basic circuit examples of TTL and CMOS. As is clear from such a circuit example, all I
In order to protect the circuit from overvoltage, the C circuit has at least the input clamp diode connected to the input side or the substrate diode connected to the output side. In addition, the IC circuit may have a parasitic diode for protecting the circuit element and stabilizing the operation.

A first power supply 32, a second power supply 34, and an ammeter 36 are used to inspect the insertion state of the terminals 24, 26, 28, and 30 on the printed circuit board of the IC component 22 as described above.
It is connected to the terminals of the IC component 22 as shown in each drawing of FIG. That is, the first power supply 32 includes the power supply terminal 24 and the ground terminal 26.
The second power source 34 is connected to the power terminal 24 or the ground terminal 26 and the input terminal 28 or the output terminal 3 via the ammeter 36.
Connect to 2. This is because the above-mentioned forward and reverse characteristics of the diode are used for detecting the incorrect insertion of the IC component 22 terminal, particularly the reverse insertion of the power supply terminal 24 and the ground terminal 26. For this reason, the sum of both power supply voltages is made larger than the rising voltage of the diode, but each power supply voltage alone is made smaller than the rising voltage. For example, in the case of a silicon diode, since the rising voltage is about 0.6V, the first
The voltage of the power supply 32 is set to about 0.4V, and the voltage of the second power supply 34 is set to about 0.2V.

In this way, when a voltage is applied to each terminal connected from the first and second power supplies 32 and 34, in the case of the open collector type TTL in the circuit configuration of FIG.
As shown in the figure, the sum of the two power supply voltages is applied to the substrate diode 38 from the positive direction and the diode 38 rises, so that a large current flows through the ammeter 36 in the arrow direction. Therefore, the indication of the ammeter 36 becomes large,
Directionality of IC component 22, that is, power supply terminal 24, ground terminal 2
It becomes clear that 6 etc. are normal insertions. When the power supply terminal 24 and the ground terminal 26 are reversely inserted, the circuit configuration shown in FIG. 10 to be described later is obtained, only a small amount of current flows, and the ammeter 36 indicates almost zero so that the terminal is erroneously inserted. Can be detected. Similarly, in the case of a CMOS inverter, a large current flows in the direction of the arrow through the substrate diode 40 at the time of normal insertion as shown in FIG. 5, but at the time of reverse insertion the circuit configuration shown in FIG.
Very little current flows. Therefore, the indication of the ammeter 36 is largely changed between the normal insertion and the reverse insertion, and the incorrect insertion of the terminal can be detected.

Next, in the case of the open collector type TTL in the circuit configuration of FIG. 1 (b), a large current flows in the arrow direction through the input clamp diode 42 this time as shown in FIG. At the time of insertion, the circuit configuration shown in FIG. 8, which will be described later, is provided, and only a small amount of current flows.
Therefore, the indication of the ammeter 36 is largely changed between the normal insertion and the reverse insertion, and the incorrect insertion of the terminal can be detected. Also, CMO
Similarly, in the case of the S inverter, a large current flows in the direction of the arrow through the input clamp diode 44 as shown in FIG.
With the circuit configuration shown in the figure, only a small amount of current flows. Therefore, the indication of the ammeter 36 is largely changed between the normal insertion and the reverse insertion, and the incorrect insertion of the terminal can be detected.

Next, in the case of the open collector type TTL in the circuit configuration of FIG. 1C, only the second power supply voltage is applied to the substrate diode 38 from the positive direction at normal insertion as shown in FIG. Only a small amount of current passes through the ammeter 36 along the dotted line without climbing. The first
The power supply 32 is almost open. Therefore, the indication of the ammeter 36 becomes almost zero, and it becomes clear that the directionality of the IC component 22, that is, the power supply terminal 24, the ground terminal 26, etc. are normally inserted. When the power supply terminal 24 and the grounding terminal 26 are reversely inserted, the circuit configuration shown in FIG. 6 described above is applied, and a large current flows, so that the ammeter 36 gives a large indication and the incorrect insertion of the terminal can be detected. Also, CMOS
Similarly, in the case of an inverter, at the time of normal insertion, only a small current flows through the substrate diode 40 as shown in FIG. 9 along the dotted line, but at the time of reverse insertion, the circuit configuration shown in FIG. A large current will flow. Therefore, the indication of the ammeter 36 is largely changed between the normal insertion and the reverse insertion, and the incorrect insertion of the terminal can be detected.

Next, in the case of the open-collector type TTL in the circuit configuration of FIG. 1 (d), at the time of normal insertion, only a small amount of current flows through the input clamp diode 42 as shown in FIG. At the time of reverse insertion, the circuit configuration shown in FIG. 4 is provided, and a large current flows. Therefore, the indication of the ammeter 36 is largely changed between the normal insertion and the reverse insertion, and the incorrect insertion of the terminal can be detected. Also, C
Similarly, in the case of a MOS inverter, the 11th
As shown in the figure, only a small amount of current flows through the input clamp diode 44 along the dotted line, but at the time of reverse insertion, the circuit configuration shown in FIG. Therefore, the indication of the ammeter 36 is largely changed between the normal insertion and the reverse insertion, and the incorrect insertion of the terminal can be detected.

However, when the IC component 22 is individually mounted on the printed circuit board as described above, it is not always necessary to use the two power sources as described above. Because, each of (a), (b) in FIG.
As shown in (c) and (d), a single power supply 46 having a voltage value corresponding to the sum of both power supply voltages is used to connect the ground terminal 2 between the ground terminal 26 and the output terminal 30 of the CMOS inverter.
6 and the input terminal 28, the power supply terminal 24 and the output terminal 30
, And between the power supply terminal 24 and the input terminal 28, the voltage applied to the substrate diode 40 and the input clamp diode 44 is the corresponding fifth voltage.
This is because it is almost the same as FIGS. 7, 7, 9 and 11. However, normally, only an IC component is rarely mounted on a printed circuit board by itself. Therefore, in a single power supply, due to the influence of other peripheral circuits, input clamp diodes, substrate diodes, other parasitic diodes, etc. The characteristic cannot be used for detecting the incorrect insertion of the terminal of the IC component.

Therefore, for two power supplies and a single power supply, a comparative study will be made on the case of a circuit in which a bypass capacitor such as a ceramic capacitor or an electrolytic capacitor is connected between the power supply terminal 24 and the ground terminal 26 of the CMOS inverter. First, in the case of two power supplies, if a bypass capacitor or the like 48 is further connected to the circuit of FIG. 9 as shown in FIG. 13, the first power supply 32 causes a current to flow in the arrow direction through the capacitor 48, Since only the voltage of the second power supply 34 is still applied to the substrate diode 40, only a very small current flows along the dotted line. On the other hand, in the case of a single power source, if a bypass capacitor 50 or the like is further connected to the circuit of FIG. 12 (c) as shown in FIG.
This time, a large current flows in the direction of the arrow. Further, even if a bypass capacitor is further connected to each of the circuit of FIG. 11 and the circuit of FIG. 12 (d), only a very small current flows through the ammeter with the two power supplies, but a large current still flows with the single power supply. Flows. By the way, even if a bypass capacitor is connected to each of the circuits shown in FIGS. 4, 6, 12 (a), and (b), a large current still flows through the ammeter and there is no change.

When carrying out such a method for detecting the incorrect insertion of the terminal of the IC component, usually, the circuit configuration is as shown in FIGS. Then it becomes convenient. Further, if this detection method is applied to an in-circuit tester, the detection rate of erroneous terminal insertion of IC components on a printed circuit board is naturally improved.

EFFECTS OF THE INVENTION According to the present invention described above, it is possible to accurately detect the incorrect insertion of the terminal of the IC component mounted on the printed board by reducing the influence of the peripheral circuit.

Further, it is possible to accurately detect the missing state of IC parts.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of each circuit to which the method for detecting incorrect insertion of an IC component terminal according to the present invention is applied. 2 and 3 are specific equivalent circuit diagrams included in each IC component shown in FIG. 4 and 5 are shown in FIG. 1 (a), FIGS. 6 and 7 are shown in FIG. 1 (b), FIGS. 8 and 9 are shown in FIG. 1 (c), and FIG. FIG. 11 and FIG. 11 are specific operation explanatory diagrams corresponding to FIG. 1 (d), respectively. FIG. 12 is a specific operation explanatory diagram with a single power source corresponding to FIGS. 5, 7, 9, and 11, respectively. FIGS. 13 and 14 are specific operational comparison explanatory diagrams of a dual power source and a single power source in consideration of peripheral circuits corresponding to FIGS. 9 and 12 (c), respectively. FIG. 15 is a diagram showing an example of each circuit to which a conventional method for detecting incorrect insertion of terminals of IC parts is applied. 22 ... IC parts, 24 Power supply terminal, 26 ... Ground terminal, 28
... input terminal, 30 ... output terminal, 32 ... first power supply, 34 ...
Second power supply, 36 ... Ammeter, 38, 40 ... Substrate diode, 42, 44 ... Input clamp diode, 4
8 ... Bypass capacitor forming peripheral circuit

Claims (1)

[Claims] 1. In a method for detecting incorrect insertion of 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 calculated from the rising voltage of a diode included in the IC component. A first power supply and a second power supply, which are large but each power supply voltage alone is smaller than its rising voltage, are used, the first power supply voltage is applied to the power supply terminal and the ground terminal, and the second power supply voltage is applied via an ammeter. A method for detecting incorrect insertion of an IC component terminal, which comprises applying a power supply terminal or a ground terminal and an input terminal or an output terminal and detecting an incorrect insertion of an IC component terminal with respect to a printed circuit board according to an instruction from an ammeter.