JPH0652291B2 - Method for determining the terminal insertion state of IC component on mounting board - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining an insertion state of a terminal of an IC component mounted on a printed 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, a current path created by a protection diode such as an input clamp diode attached to a TTL circuit included in an IC component or a substrate diode between a collector of a transistor and ground is generally used, A constant current source is applied between the power supply terminal or ground terminal of the IC component and the input terminal or output terminal by the contact of the probe to flow a current, and the voltage (potential difference) between the terminals.
To check whether the insertion is normal or incorrect (reverse insertion).
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 IC components mounted on a printed circuit board, other circuits connected to the terminals of the IC components affect the measurement,
In many cases, there is a slight difference between the voltage values of normal insertion and erroneous insertion, for example, only a few mV. 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.
As for No. 8, for an IC component that has a power supply terminal, a ground terminal, an input terminal, and an output terminal mounted on the printed circuit board to be inspected, the sum of both power supply voltages is calculated from the rising voltage of the 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. It is applied to the power supply terminal or the ground terminal and the input terminal or the output terminal, the terminal insertion state of the IC component on the mounting board is detected by the instruction of the ammeter, and the current value and the normality which is the standard previously measured. The method of comparing the current value at the time of insertion with the current value at the time of normal insertion and the difference between the current value at the time of incorrect insertion and that at the time of incorrect insertion is presented. And ammeter connected Select command (pattern surrounding the lead holes), ammeter increases the measured value to be indicated, he said to the effect to be advantageously during erroneous insertion small to substantially zero in the normal insertion.

However, when determining the terminal insertion state of the IC component on the mounting board as described above, even if the land to which the second power source or the like is connected is limited, even if the erroneous insertion is actually made, it is exceptional. There is a problem in that some current flows to some extent due to the influence of peripheral circuits, or almost no current flows even if it is inserted properly. This is because, in the latter case, exceptionally, the protection diode which should normally be included in the IC component is not inserted.

The present invention has been made in view of such conventional problems, and provides a method for accurately determining a terminal insertion state of an IC component on a mounting board for various IC components and a mounting board. With the goal.

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

The method of determining the terminal insertion state of the IC component on the mounting board is the sum of the two power supply voltages for the IC component 10 having the power supply terminal 18, the ground terminal 20, the input terminal 22, and the output terminal 24 mounted on the printed board. Using the first power supply 12 and the second power supply 14 which are larger than the rising voltage of the protection diodes 26, 28, 30, 32 normally included in the IC component 10 but smaller than the rising voltage at each power supply voltage alone,
The first power supply voltage is applied to the power supply terminal 18 and the ground terminal 20, and the second power supply voltage is applied to the power supply terminal 18 or the ground terminal 20 and the input terminal 22 or the output terminal 24 via the ammeter 16 to obtain the ammeter. According to the measurement value indicated by 16, a reference value is set from the measurement value at the time of normal insertion, and that value is compared with the measurement value at the time of inspection to determine normal insertion or erroneous insertion. At that time, the measured values at the time of normal insertion are divided into those below a certain value and those above a certain value, and the first and second reference values corresponding to the former and the latter are changed from the first reference value to the second reference value. Set larger and set each, and compare those reference values with the measurement values at the time of inspection, normal insertion when the measurement value at the time of inspection corresponding to the former is less than the first reference value, incorrect insertion when it is greater than the first reference value. If the measured value at the time of inspection corresponding to the latter is equal to or more than the second reference value, it is determined to be normal insertion, and if it is smaller than the second reference value, it is determined to be erroneous insertion.

Operation With the above configuration, the measured current value at the time of normal insertion is divided into those below a certain value and those above a certain value, and each is allowed when setting the first and second reference values corresponding to the former and latter. In consideration of the range, the second reference value can be set larger than the first reference value. Therefore, when the measured value at the time of inspection corresponding to the former is less than the first reference value, almost no current flows, but there is no diode in the predetermined position of the IC component, or the diode is in the reverse direction. Then, it can be determined that the insertion is normal when the diode characteristic is not shown. Further, when the measured value at the time of the inspection is larger than the first reference value, the current should have hardly flowed, but the current having a certain size has flowed, so it is determined that the insertion is incorrect. it can. or,
When the measured value at the time of inspection corresponding to the latter is equal to or higher than the second reference value, a large current obviously flows, so that it can be determined that the insertion is normal. Furthermore, when the measured value at the time of inspection is smaller than the second reference value, a certain amount of current is flowing, but it is smaller than expected and it can be determined that the insertion is incorrect.

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

FIG. 1 is a circuit diagram in which the method for determining the terminal insertion state of an IC component on a mounting substrate according to the present invention is applied to a substrate on which an IC component is mounted and the current between the terminals is measured. In the figure, 10 is an IC component mounted on a printed circuit board, 12 is a first power supply, 14 is a second power supply, and 16 is an ammeter. The figure shows a case where the IC component 10 is normally inserted in the printed circuit board. This IC component 10 has a power supply terminal 1 on the outside.
It has 8, a ground terminal 20, an input terminal 22, and an output terminal 24. Moreover, as shown in FIG. 2 (a), two protection diodes 26 and 28 are normally included in the inside of the power supply, ground and output terminals 18, 20 and 24 in an equivalent circuit. . However, the cathodes are connected in series between both terminals 18 and 20 toward the power supply terminal side, and the intermediate point is further connected to the output terminal 24. Further, as shown in FIG. 2 (b), the power supply, ground, and input terminals 18, 20 and 22 include two protection diodes 30 and 32 in an equivalent circuit. However, both diodes 30 and 32 have their cathodes connected in series between the power supply and ground terminals 18 and 20 so as to face the power supply terminal side, and the midpoint thereof is connected to the input terminal 22.

In order to inspect the insertion state of each terminal 18, 20, 22, and 24 on the printed circuit board of the IC component 10 as described above, the first power supply 12 is connected to the power supply terminal 18 and the ground terminal 20, and the second power supply 14 is connected. The power supply terminal 18 or the ground terminal 20 and the input terminal 22 or the output terminal 24 are connected via the ammeter 16. However, the circuit configuration shown in FIG. 2 (a) is normally inserted, but if it is inserted incorrectly (reverse insertion), the circuit configuration shown in FIG. 2 (b) is obtained, and the positions of the first power supply 12 are changed. The power supply terminal 18 and the ground terminal 20 are connected, and the second power supply 14 and the ammeter 16 are connected to the ground terminal 20 and the input terminal 22. With these circuit configurations, it is possible to utilize the forward and reverse characteristics of the diode described above for determining the terminal insertion state of the IC component 10, that is, for detecting the reverse insertion of the power supply terminal 18 and the ground terminal 20. Therefore, the sum of both power supply voltages is the diode 2
6, 28, 30 and 32 are higher than the rising voltage, but each power supply voltage alone is lower 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 12 is set to about 0.4V and the voltage of the second power supply 14 is set to about 0.2V.

Therefore, at the time of normal insertion, the sum of both power supply voltages is applied in the forward direction of the protection diode 28 and rises, so that a large current flows in the ammeter 16 in the arrow direction. In addition, since the second power supply voltage is applied in the forward direction of the protection diode 30 and the sum of both power supply voltages is applied in the reverse direction to the protection diode 32 during reverse insertion, they do not rise, and the ammeter 16 is indicated by the arrow. Only a small amount of current flows in the direction along the dotted line.

However, in reality, even if the insertion is incorrect, some current may exceptionally flow a certain amount of current due to the influence of peripheral circuits. In addition, even if it is inserted normally, there is an exception that the protection diode is not inserted, so that there is a diode that does not exhibit diode characteristics and hardly flows a current. After all, the IC component 10 can be roughly classified into two types, that is, a current hardly flows through the ammeter 16 and a current flowing through the ammeter 16 regardless of whether the IC component 10 is normally or incorrectly inserted.

Therefore, each terminal 18 of the IC component 10 on the mounting board,
When determining the insertion state of 20, 22, and 24, first, the current at the time of normal insertion is measured on a non-defective substrate, and the value is divided into a certain value or less, for example, 10 μA or less and a value larger than the certain value, 10 μA. Next, in order to compare with the measurement value at the time of inspection, the first and second reference values are set according to the former and latter cases. At that time, both the first and second reference values consider the allowable range with respect to the measured current value at the time of normal insertion, for example, the first reference value.
The reference value is set to 50 μA regardless of the measured current value at the time of normal insertion, and the second reference value is set larger than the first reference value by adding an allowable value to the current value, for example, 80 μA. Then, when the measured value at the time of inspection corresponding to the former is less than or equal to the first reference value, it is determined that the insertion is normal, and when it is greater than that value, it is determined that the insertion is incorrect.
If the measured value at the time of inspection corresponding to the latter is equal to or larger than the second reference value, it is determined as normal insertion, and if it is smaller than that value, it is determined as incorrect insertion. For example, the IC component 10 to be inspected is 50 μA
When the measured current value is 8 μA, it can be determined that the insertion is normally performed because it is in the normal insertion region as shown in the bar graph of FIG. 3 (a).
If the IC component 10 has a reference value of 80 μA, if the measured current value is 100 μA, it is in the normal insertion area as shown in the bar graph of FIG. It can be determined that there is. In this way, the IC component 10 to be inspected is divided into two croups having different reference values according to the measured values at the time of normal insertion, and normal insertion or erroneous insertion is determined for each group with the reference value as a boundary. If done, the determination can be made more accurately. Therefore, erroneous determinations due to different lots of IC parts and erroneous determinations based on temperature characteristics are reduced.

Generally, it is rare to mount only the IC component 10 on a printed circuit board as a single component, and a bypass capacitor such as a ceramic capacitor or an electrolytic capacitor is provided between the power supply terminal 18 and the ground terminal 20 as shown in FIG. 34
Are connected. In this case, as shown in (a), first, the first power source 12 is connected to apply a voltage, the capacitor 34 is charged to eliminate the transient phenomenon, and then the second power source 14 and the ammeter 16 are connected. It is advisable to take the procedure of further applying a voltage.

Such a method for determining the terminal insertion state of the IC component on the mounting board can be applied to the in-circuit tester. At that time, a processing program to which a subroutine for determining the terminal insertion state as shown in FIGS. 5 and 6 is added is stored in the ROM of an arithmetic unit such as a microcomputer which constitutes the in-circuit tester. Note that FIG. 5 is a flow chart including steps P1 to P4 showing a reference value setting subroutine, and FIG. 6 is a flow chart including steps P5 to P11 showing a determination subroutine based on the set reference value. In order to execute this reference value setting subroutine, first, at P1, a good mounting board in which IC components are normally inserted is used, and the current is measured by the circuit configuration shown in FIG. 1 or 4 to obtain data. Absorbs. Then P
Go to 2. In P2, the measured current value is a constant value, for example 10 μA
Determine if If YES, go to P3, and if NO, go to P4. At P3, a first reference value that is a threshold value is calculated and set to, for example, 50 μA. In P4, the second reference value is calculated and set to 80 μA, for example.

Next, in order to execute the determination subroutine based on the set first and second reference values, first in P5, it is determined whether or not the mounting substrate to be inspected has the first reference value. Yes
If NO, go to P6, and if NO, go to P10. At P6, the measured value and the first reference value are compared. Then go to P7. P7
Then, it is determined whether the measured value is less than or equal to the first reference value. If YES, go to P8 and determine GOOD, that is, normal insertion. If NO, go to P9 and determine NG, that is, erroneous insertion. Even on P10, the measured value and the second reference value are compared, and P11
Go to At P11, it is determined whether the measured value is the second reference value or more.
If YES, go to P8, and if NO, go to P9. As a result, it is possible to speed up the determination of the terminal insertion state of the IC component on the mounting board.

EFFECTS OF THE INVENTION According to the present invention described above, the IC component to be inspected is divided into two groups having different reference values according to the measurement values at the time of normal insertion, and the reference values are used as boundaries for each group to perform normal operation. Since it is determined whether the IC component has been inserted or erroneously inserted, it is possible to accurately determine the insertion state of the IC component for various IC components or mounting boards.

[Brief description of drawings]

FIG. 1 is a circuit diagram in which the method for determining the terminal insertion state of an IC component on a mounting substrate according to the present invention is applied to a substrate on which an IC component is mounted, and the inter-terminal current is measured, and FIG. 2 is a general circuit diagram of the IC component. It is a figure which shows a different internal circuit. FIG. 3 is a diagram for explaining processing after current measurement by the determination method. FIG. 4 is a circuit diagram showing a process of applying the same determination method to a substrate on which a capacitor is mounted together with an IC component and measuring the inter-terminal current. FIG. 5 is a flow chart showing a reference value setting subroutine adopted in an in-circuit tester to which the same determination method is applied, and FIG. 6 is a flow chart showing a determination subroutine based on the reference value. 10 ... IC parts, 12, 14 ... First and second power supplies, 16 ...
Ammeter, 18, 20, 22, 24 ... power supply, ground, input,
Output terminals, 26, 28, 30, 32 ... Protection diodes

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 the two power supply voltages is higher than the rising voltage of the protection diode normally included in the IC component, but each power supply voltage alone uses the first power supply and the second power supply that are smaller than the rising voltage. Apply the second power supply voltage to the power supply terminal or the ground terminal and the input terminal or the output terminal through the ammeter, and the measurement value indicated by the ammeter. In the method for determining the terminal insertion state of the IC component on the mounting board that determines the normal insertion and the incorrect insertion by setting a reference value from the It is divided into those below a certain value and those above a certain value, and the first and second reference values corresponding to the former and the latter are respectively set by making the second reference value larger than the first reference value, and those reference values are set. And the measured value at the time of inspection are compared, 'S measurements during a test corresponding to the first
If it is less than the reference value, it is determined as normal insertion, and if it is greater than that value, it is determined as incorrect insertion. If the measurement value corresponding to the latter is greater than or equal to the second reference value, it is determined as normal insertion, and if it is less than that value, it is determined as incorrect insertion. An IC on a mounting board characterized in that
Method for determining the terminal insertion state of parts.