JP3396525B2 - Conductor position detection method and electronic component lead inspection device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductor position detecting method for detecting the position of a conductor by measuring an electrostatic capacitance and a lead inspection apparatus for electronic parts such as ICs using the same.

[0002]

2. Description of the Related Art When an electronic component, for example, an IC, is mounted on a printed circuit board and soldered, if the IC lead is bent, the tip of the IC lead is lifted from the land of the printed circuit board or displaced from the land. Therefore, soldering failure is likely to occur. Therefore, in the IC mounting process, it is necessary to measure the bending state of the IC lead for each IC in advance to exclude defective products. In this case, IC
The allowable deformation amount of the lead is, for example, a value of several tens of μm or less for floating deformation, and therefore, highly accurate measurement is required.

As an IC lead inspection apparatus used for such an application, there is one using an optical displacement sensor as described in, for example, Japanese Patent Laid-Open No. 4-15507. In this configuration, a light beam is emitted from the displacement sensor to the tip of the IC lead, and the reflected light is received by a photoelectric conversion element to measure the distance from the IC lead based on the angle of the reflected light. Is. If the IC lead is bent and deformed, the distance between the displacement sensor and the IC lead is different from the reference value, so that it can be detected.

However, in the inspection apparatus having the above structure, since the displacement sensor uses an extremely thin light beam, one IC is used.
In order to measure the bending deformation of all the IC leads of the chip, it is necessary to mechanically move the optical displacement sensor to sequentially irradiate the tip of each IC lead with the light beam. For this reason, a mechanical feed mechanism for sequentially feeding the optical displacement sensor in the arrangement direction of the IC leads is required, and as a result, the deformation detection accuracy of each IC lead is restricted by the accuracy of the feed mechanism. However, there is a problem in that sufficient accuracy may not be obtained, and it takes a relatively long time to measure all IC leads.

On the other hand, the following structure is also provided as a structure that can eliminate the need for a mechanical feeding mechanism. This is because two linear light sources are provided above and to the left of the IC lead group, and collimated rays are emitted toward the IC lead group in directions orthogonal to each other, and the light is emitted to the lower and right sides of the IC lead group. The light is received by a line sensor such as a CCD provided on one side. In this configuration, the light from the linear light source is incident on the line sensor, and at that time, a shadow is generated in a portion corresponding to each IC lead. Therefore, the position and size of the shadow when there is no bending deformation in each IC lead is determined. If you memorize it, depending on the position and size of the shadow of the IC lead of the IC to be inspected,
The bending deformation of the lead can be detected.

[0006]

However, in the above-mentioned inspection apparatus, since the line light source and the line sensor have to be positioned above, below, to the left and right of the IC, there is a drawback that the inspection apparatus as a whole becomes large. Moreover, the IC becomes large and the IC
If the lead group becomes long, the line light source must be made long in accordance with this, which makes it difficult to secure the parallelism of the inspection light beam, which eventually causes a decrease in measurement accuracy.

Therefore, since the IC lead is a conductor,
It is possible to detect the position of the lead, that is, the deformation of the lead, by measuring the electrostatic capacitance between the IC lead and the electrode provided opposite thereto. That is, for example, a large number of electrodes corresponding to each IC lead are formed on an inspection board and covered with an insulating coating, the IC is set on the inspection board by a mounting mechanism, and electrostatic charges between the IC lead and each electrode are set. The capacity is measured. When the IC lead is bent and deformed upward, the tip end of the IC lead is located away from the electrode of the inspection board, so that the capacitance becomes small. Therefore, the capacitance between the electrode and the IC lead may be measured and compared with a reference value, and when the measured capacitance is smaller than the reference value, it may be determined that the IC lead has a bending deformation. . According to this, when the IC lead is bent and lifted up from the electrode, the bend can be electronically detected, and therefore the IC lead can be quickly and accurately inspected. It should be possible to obtain the excellent advantage that the inspection apparatus as a whole can be constructed in a small size.

However, on the other hand, it is inevitable that the mounting mechanism for setting the IC on the inspection substrate has some positioning error. Therefore, if the mounting mechanism causes the IC lead to shift laterally from the electrode, If is set on the inspection substrate, the capacitance between the IC lead and the electrode is reduced by the amount of the deviation. To explain this situation in detail, if the measurement electrode 1 and the lead 2 of the electronic component have a relationship as shown in FIG. 1 (A), the capacitance related to the position of the lead 2 with respect to the electrode 1 in the direction of displacement. The change characteristics of C are as shown by the solid line in FIG.
Shows the maximum value when corresponds to the center of the electrode 1, and the capacitance C tends to decrease rapidly as the “deviation amount” x from the center increases. Under such change characteristics,
Due to the positioning error of the mounting mechanism, the electronic component is electrode 1
If the capacitance is set off the center of, the capacitance will decrease according to the "deviation amount". Therefore, depending on the "deviation amount", the measured capacitance will fall below the reference value, and the IC lead Although there is no floating deformation, it may be judged that the IC lead is deformed. That is, in a position detection method in which one electrode is simply provided for a conductor such as an IC lead, the capacitance between them is measured, and the position of the conductor is detected based on the capacitance, the conductor and the electrode are Since it is not possible to distinguish between the horizontal "deviation" and the vertical "float" (face-to-face distance), it is not possible to accurately detect the position.

The present invention has been made in view of the above circumstances. Therefore, in a position detecting method for detecting the position of a conductor by measuring the electrostatic capacitance between the conductor and the measuring electrode,
This is to enable the difference and the facing distance to be distinguished and grasped. Another object of the present invention is to apply this method to a lead inspection device for electronic parts, thereby enabling a compact inspection device as a whole while inspecting deformation of leads of electronic parts such as ICs at high speed and accurately. An object of the present invention is to provide a lead inspection device for an electronic component, which can perform the inspection accurately regardless of the positioning error of the mount mechanism for setting the electronic component on the inspection board.

[0010]

In order to achieve the above object, the position detecting method of the present invention provides a pair of measuring electrodes on a conductor so as to be opposed to each other, and at least one of these measuring electrodes is provided.
Front through an insulating film formed to cover the conductor side
It is characterized in that two capacitances between each measurement electrode and a conductor are measured, and a displacement amount and a facing distance of the conductor with respect to the measurement electrode are calculated based on each capacitance (claim). Invention 1).

The electronic component lead inspection apparatus of the present invention places the electronic component to be inspected at a predetermined position on the inspection substrate and inspects the bending deformation of the lead derived from the electronic component. Therefore, a pair of measurement electrodes provided on the inspection board and facing the leads led out from the package of the electronic component, an insulating film formed on the inspection board so as to cover each of these measurement electrodes, and each lead are measured. Capacitance measuring means for measuring each capacitance between the lead and each measurement electrode in a state of being opposed to the electrode through the insulating film, and the lead with respect to the measurement electrode based on each measured capacitance. The present invention is characterized in that a state determining means for calculating the amount of deviation and the amount of floating is provided (the invention of claim 2).

Further, in the lead inspection apparatus of the present invention, a package side electrode corresponding to the package of the electronic component is provided on the inspection board, and the capacitance between the lead and the measurement electrode is measured by the package side electrode and each measurement. The measurement may be performed based on the capacitance with the electrode (the invention of claim 3).

[0013]

According to the conductor position detecting method of the present invention,
As shown in FIG. 2, a pair of measuring electrodes 2a and 2b are provided on the conductor 1.
Face each other, and the capacitance between each of the measurement electrodes 2a and 2b and the conductor 1 is measured. For example, with reference to the facing state shown in FIG. 2A, the capacitance between the conductor 1 and one measurement electrode 2a in that state is Ca0, and the capacitance between the other measurement electrode 2b is Assuming that Cb0 is, as shown in FIG. 2B, when the conductor 1 increases the facing distance without causing “deviation” with respect to each of the measuring electrodes 2a and 2b, each measured at that time. The capacitances Ca1 and Cb1 are both smaller than the capacitances Ca0 and Cb0 in the reference state (Ca1 <Ca).
0, Cb1 <Cb0).

Further, as shown in FIG. 2C, the conductor 1
Causes a “shift” on the left side without increasing the facing distance to each of the measurement electrodes 2a and 2b,
The capacitance Ca2 on the left side measured at that time is larger than the capacitance Ca0 in the reference state (Ca2> Ca0), and conversely, the capacitance Cb2 on the right side is the capacitance Cb0 in the reference state. Is smaller than that (Cb2 <Cb0). Further, as shown in FIG. 2D, in the case where the conductor 1 causes a “shift” on the left side while increasing the facing distance to each measurement electrode 2a, 2b, the left side measured at that time Capacitance of Ca2
Is smaller than the capacitance Ca0 in the standard state (Ca3
<Ca0) and the capacitance Cb3 on the right side is much smaller than the capacitance Cb0 in the reference state (Cb3 << Cb
0).

Therefore, the conductor 1 and each of the measuring electrodes 2a and 2b
And the capacitance between the
By comparing with a0 and Cb0, each measuring electrode 2a, 2b
The position can be detected separately for the “deviation” and the “face-to-face distance” of the conductor 1 with respect to. The measurement electrode is
Since it is configured to cover, the conductivity depends on the relative permittivity.
It is possible to increase the capacitance between the
It becomes possible to improve accuracy. Also, if the insulation film
If you try to measure the capacitance without the
Prevents contacting the measuring electrodes and shorting them
In order to keep the conductor floating from the electrode.
I have to Then, first, the distance between the electrodes
Measurement because it has to be set very accurately
Positioning difficulty in the direction of approaching the electrode
The difference will not affect the measurement error of the air gap size.
It Moreover, does the conductor float in the air?
Therefore, it will be measured in a state different from that at the time of mounting.
On the other hand, in the configuration of the present invention, the conductor is simply placed on the insulating film.
If an electric body is placed, the distance between the electric conductor and the electrode will naturally be
Therefore, the measurement error can be reduced.

Further, in the lead inspection apparatus of the present invention,
In order to inspect the leads of an electronic component, the electronic component to be inspected is set at a predetermined position on the inspection board, and the leads are made to face the pair of measurement electrodes via the insulating film, and in that state The capacitance between the measuring electrode and the lead is measured.

Here, in the lead inspection apparatus of the present invention, 1
Since the capacitance is measured between each pair of measuring electrodes and the lead, as is clear from the above description of the method for detecting the position of the conductor, both of these capacitances are similar to the reference capacitance. When the size is small, it can be determined that the lead is deformed so as to be lifted from each measurement electrode.

Further, when there is an imbalance between the measured capacitances, it can be determined that the lead has a “deviation” that is offset toward the measurement electrode side having a large capacitance. In the case where the electronic component to be measured has a configuration in which a large number of leads are led out from the package like an IC, if there is a positioning error when the IC is set on the inspection board, the same applies to each lead. "Misalignment" occurs. Therefore, as a result of the above-mentioned measurement, each lead has a similar “deviation” in the same direction.
Is detected, it is considered to be a positioning error of the electronic component with respect to the inspection board. Therefore, it is sufficient to ignore the “deviation” and inspect the lead.

Further, in the lead inspection apparatus of the present invention, since the measuring electrode is covered with the insulating film, the capacitance between the lead and the measuring electrode can be increased according to the relative permittivity of the measuring electrode, and the measurement accuracy can be improved. It is possible to improve the
Further, since the lead can be placed on the measurement electrode in an electrically non-contact state, the lead can be inspected in a state close to the mounted state of the electronic component.

That is, if it is attempted to measure the capacitance without an insulating film, it is necessary to prevent the leads from floating from the electrodes in order to prevent the leads from coming into contact with the measurement electrodes and short-circuiting them. must not. Then, the distance between the electrode and the electrode must be set very accurately first, which causes difficulty in positioning in the direction of approaching the inspection board, and the error affects the measurement error of the air gap dimension. Become. Moreover, since the leads are lifted up in the air, the measurement is performed in a state different from the state at the time of soldering on the printed circuit board. On the other hand, in the configuration of the present invention, since it is sufficient to simply place the leads on the insulating film, there are few problems in setting the distance between the electrodes and the leads are in contact with the insulating film. The inspection can be performed in a state very close to the state when the electronic component is mounted.

In order to measure the capacitance between the lead and each measurement electrode, it is not limited to directly applying a voltage to the lead and each measurement electrode and measuring the flowing current, but the invention of claim 3 is also applicable. As described above, the capacitance between the package-side electrode and the measurement electrode provided on the inspection board can be measured. In this case, the combined capacitance of the capacitance between the portion of the lead located inside the package of the electronic component and the package-side electrode and the capacitance between the lead and the measurement electrode is measured. Since the former is a fixed value that is not affected by bending deformation of the lead, the latter can be easily calculated.

[0022]

As described above, according to the conductor position detecting method of the first aspect, the two measuring electrodes are provided to measure the respective capacitances of these electrodes and the conductor. The position can be detected separately for the “deviation” and the “face-to-face distance”. Moreover, the measurement electrode is covered with an insulating film.
Therefore, according to the relative permittivity of the conductor and the measurement electrode
The capacitance between the two can be increased to improve the measurement accuracy.
It is also possible to place a conductor on the insulation film.
If this is done, the distance between the conductor and the electrode will naturally be constant and measured.
It has an excellent effect that the constant error can be reduced.
To do. Further, according to the lead inspection apparatus of claim 2,
Two measuring electrodes are provided, and two electrodes are provided between each measuring electrode and the lead.
Since the capacitance of the seed is measured, the "deviation" of the lead from the measurement electrode and the "floating" of the lead can be detected separately. Therefore, for example, it is possible to perform accurate inspection by distinguishing the capacitance change caused by the positioning error of the electronic component on the inspection substrate and the capacitance change caused by the bending of the lead. Moreover,
Since the measuring electrode is covered with an insulating film and the electronic components can be set on it, it is possible to obtain an appropriate inspection result by inspecting in a state close to the mounting state of the electronic component, for a more accurate inspection. It has an excellent effect that it can be performed. Further, according to the lead inspection apparatus of the third aspect in which the package-side electrode is provided, there is an additional effect that the capacitance between the lead and the measurement electrode can be easily measured.

[0023]

EXAMPLE An example in which the conductor position detecting method according to the present invention is applied to an IC lead inspection apparatus will now be described with reference to FIG.
It will be described with reference to FIGS.

First, the IC to be inspected in this embodiment will be briefly described. This is as shown in FIG.
A large number of IC leads 12 (only one is shown) are drawn out in a row from the side of the package 11. The tip of each IC lead 12 is a flat part that is soldered to a land of a printed circuit board (not shown). 12a and IC
The base end side of the lead 12 has a well-known configuration that is continuous with the in-package conductor portion 12b located in the IC package 11. In this embodiment, the IC lead 12 has a width WIC of 300 μm, a thickness of 100 μm, and a flat portion 12a of 800 μm in length. To assemble the product by mounting the IC 13 on a printed circuit board (not shown), the IC package 11 is sucked and conveyed by a suction device of an assembly robot (not shown), and the flat portion 12a of the IC lead 12 is placed on the land of the printed circuit board. The printed circuit board is placed so as to be in contact with it, and soldering is performed in that state. Then, before the IC is supplied to the suction device of such an assembly robot, the IC to be inspected by the mounting mechanism.
The presence or absence of bending deformation of each IC lead 12 is inspected in a state where 13 is set at a predetermined position on the inspection board 14 of this embodiment. Although not shown, the mount mechanism has a suction pad for vacuum suction at the tip of the arm, and has a well-known configuration for positioning and transporting the IC package 11 at a predetermined position on the inspection board 14 in a state where the suction pad sucks the IC package 11. is there.

Now, FIG. 3 also shows the electrode portion of the lead inspection apparatus of this embodiment. That is, a large number of measurement electrodes 1 corresponding to the package side electrodes 15 and each IC lead 12 are formed on the inspection board 14 by the printed wiring means.
6 is formed. Of these, the package side electrode 15
Is formed in a frame shape corresponding to the outer circumference of the bottom surface of the IC package 11, and the measurement electrode 16 is composed of two electrodes 16a and 16b adjacent to each other via a gap 16c, each extending in the extension direction of the IC lead 12. It is formed to have a rectangular shape. Although not shown for simplification of the drawing, the same number of pairs of electrodes 16 as the IC leads 12 are provided.
The pair of a and 16b are arranged in a line on the inspection substrate 14 in the same manner as the IC lead 12 group. Further, as shown in FIG. 7, an insulating film 17 is formed on the surface of the inspection substrate 14 and covers the electrodes 15, 16a, 16b group and the lead wire portions thereof. Here, the measurement electrodes 16a and 16b corresponding to the IC leads 12 will be described more specifically with reference to FIG.
The width W of a and 16b is 110 μm, and the length L is IC
It is 800 μm, which is the same as the flat portion 12a of the lead 12, and the distance X between the center lines of the measurement electrodes 16a and 16b is 250 μm. In this state, the capacitance generated between the flat portion 12a of the IC lead 12 and each of the measurement electrodes 16a and 16b is about 0.1 pF, and the conductor portion 12 in the package of the IC lead 12 is
The electrostatic capacitance generated between b and the package side electrode 15 was about 1.4 pF.

A capacitance measuring circuit 20 corresponding to the capacitance measuring means and a state determining circuit 30 corresponding to the state determining means for each of the above electrode groups are constructed as shown in FIG. In the figure, the capacitance C between the measurement electrode 16a or 16b and the package side electrode 15 is indicated by one capacitor symbol for each measurement electrode 16a or 16b. The basic principle of the capacitance measuring circuit 20 of this embodiment is as follows.
An alternating voltage of a predetermined frequency is applied from the oscillation circuit 21 between the measurement electrode 16a or 16b and the package side electrode 15,
The capacitance between the electrodes is measured based on the magnitude of the current flowing between the electrodes. One of the output lines of the oscillation circuit 21 is connected to the ground line, and the other is connected to the selection circuit 22. The selection circuit 22 is the measurement electrode 1
6a, 16b is provided with the number of switch elements 22a of one-circuit, two-contact type corresponding to the number of electrode pairs (the number of IC leads 12). As shown in FIG. 5, the common contact side of each switch has each measuring electrode 16a, It is connected to 16b. The selection circuit 22 has a function of selectively connecting one of the many measurement electrodes 16a or 16b to the oscillation circuit 21 and grounding the other measurement electrodes 16a and 16b to the ground line.

On the other hand, the package side electrode 15 is connected to the capacitance measuring circuit 20 and measures the electrostatic capacitance C between the measurement electrode 16a or 16b and the package side electrode 15. An equivalent circuit relating to the capacitance C of each IC lead 12 when the IC 13 is placed on the inspection board 14 is as shown in FIG. In the figure, c
α and cβ are the measurement electrode 16a or 16b and the IC lead 12
Between the flat portion 12a and C3 is the IC package 1
1 shows the capacitance between the in-package conductor portion 12b located inside 1 and the package side electrode 15, and C4 and C5 show the capacitance between the package side electrode 15 and the measurement electrodes 16a and 16b.
Here, C4 and C5 are fixed values determined by the arrangement pattern of each electrode on the inspection substrate 14, and C3 is also a fixed value determined by the shape of the in-package conductor portion 12b located in the IC package 11. Therefore, only cα and cβ change depending on the state of each IC lead 12 (“floating” or “deviation” from the inspection substrate 14), and accordingly the static electricity between the measurement electrode 16a or 16b and the package side electrode 15 changes. The capacitance C changes.

In order to measure the electrostatic capacitance C, the capacitance measuring circuit 20 in this embodiment, as shown in FIG. 5, is an operational amplifier 23, a bandpass filter 24, and an inverting amplifier type.
The absolute value circuit 25 and the low pass filter 26 are provided. Here, when the AC voltage from the oscillation circuit 21 is applied to any one of the measurement electrodes 16a or 16b selected by the selection circuit 22, the entire static electricity is applied between the measurement electrode 16a or 16b and the package side electrode 15. A current corresponding to the capacitance C flows, which is voltage-converted by the current-voltage conversion resistor 27, which is amplified and becomes the output voltage of the operational amplifier 23. The capacitor 28 connected in parallel with the current-voltage conversion resistor 27 is for compensating for phase rotation due to stray capacitance between the input of the operational amplifier 23 and the ground line. The output voltage of the operational amplifier 23 passes through the bandpass filter 24, is double-wave rectified by the absolute value circuit 25, and is smoothed by the lowpass filter 26. Therefore, the capacitance measuring circuit 20 outputs a level corresponding to the electrostatic capacitance C. DC voltage is output. Since the cutoff frequency of the low-pass filter 26 affects the response frequency of the circuit, it is desirable that the cutoff frequency be set to a relatively large value when performing high-speed measurement. The band-pass filter 24 is preferably a solid filter such as a ceramic filter or the like, and is for removing internal noise of the operational amplifier 23 in the preceding stage and external noise picked up from the electrode group.

On the other hand, the state discriminating circuit 30 is also constructed as shown in FIG. 5, and the DC output voltage from the capacitance measuring circuit 20 is converted into a digital signal by the A / D converting circuit 31 and given to the arithmetic processing circuit 32. . In this arithmetic processing circuit 32, the IC lead 12 is based on each combined capacitance C measured for each IC lead 12 of the IC 13 to be inspected.
And the respective capacitances cα between the measuring electrodes 16a and 16b,
cβ is calculated, and the measurement electrodes 16a, 16a of the IC lead 12 are
The "deviation" and the "float (facing distance)" for 16b are calculated, and those values are compared with the reference value stored in the reference value storage circuit 33. As a result, "deviation" and "floating"
If any of the values is larger than those reference values, that effect and the number of the IC lead 12 are stored. The inspection of each IC lead 12 is performed one by one until all the IC leads 12 are completed.

Then, at least one IC lead 12
If it is detected that the value of "deviation" or "float" is larger than the reference value, the corresponding IC is not shown so that it is not adsorbed by the hand of the assembly robot. It is supposed to be excluded by the exclusion mechanism. In addition, there are many “deviations” in the IC leads 12
If a similar amount occurs in
Since it is considered that this is caused by the positioning error of the mounting mechanism for setting C13, the quantitative "deviation" is subtracted and compared with the reference value.

Now, the method of detecting the position of the IC lead 12 in this embodiment will be described in detail. The principle of the position detecting method according to the present invention is as described in the section “Operation” with reference to FIG. 2. However, in order to actually calculate the amounts of “deviation” and “float” based on the principle. Is the respective capacitances cα, cβ
Two formulas showing the “deviation amount” x and the “floating amount” d with the variables are respectively made, and the respective capacitances c measured
Both quantities x and d are calculated by substituting α and cβ.
It is best to create both mathematical expressions by drawing a graph from an experiment and deriving an approximate expression from this, because the conductor to be measured and the shape of each measurement electrode have a great influence. In the case of the present embodiment, each capacitance cα, c
The “deviation amount” x was obtained by the following equation using the sum of β (S = cα + cβ) and the difference (D = cα−cβ) as parameters. Note that t3 to t0 and u3 to u0 are constants that are easily determined by experiments. x = k · D ³ + l · D ² + m · D + n Here, each coefficient k, l, m, n is c as shown in the following equation.
It is a value with the sum S of α and cβ as a parameter.

[0032] k = t3 · exp (u3 · S) l = t2 · S u2 m = t1 · S u1 n = t0 · S u0 Also, formulas showing the "floating amount" d is towards the closer the IC lead 12 Capacitance c for measuring electrode 16a or 16b
Measurement electrode 16 closer to IC lead 12 with α or cβ
It is expressed using the "deviation amount" Xα or Xβ between the center of a or 16b and the center of the IC lead 12 (see FIG. 7). When the case where the measurement electrodes 16a and 16b are displaced to the right from the center is positive and the case where they are displaced to the left are represented as negative, the respective "deviation amounts" are Xα = x + x1 and Xβ = x-x2. Therefore, as shown in FIG. 7, when the IC lead 12 approaches the left measurement electrode 16a side, the following equation is obtained.

D = {(v1 · Xα + w1) / cα} −v2 · exp (w2 · Xα) Here, v1, v2, w1 and w2 are constants easily determined by experiments.

Therefore, in the present embodiment, the arithmetic processing circuit 32 performs an arithmetic operation based on the above-mentioned two equations in which the respective constants are substituted, so that the "deviation of the IC lead 12" based on the respective electrostatic capacitances cα and cβ. The “amount” x and the “float amount” d are calculated.

Next, the operation of this embodiment will be described. In the above configuration, the IC to be inspected is adsorbed on the IC package 11 portion by the adsorption device of the mounting mechanism (not shown), and the IC lead 12 group forms a pair of measurement electrodes 16a,
The IC package 11 is positioned on the inspection substrate 14 so as to face 16b and the package-side electrode 15. In this case, the flat portion 1 of each IC lead 12
2a is placed directly above the measurement electrodes 16a and 16b with the insulating film 17 interposed therebetween, and comes into contact with and faces each other. As shown in the equivalent circuit of FIG. It is formed.

When the IC is set at the predetermined position in this way, each switch element 22a of the selection circuit 22 is switched in response to a signal from the control circuit 40 of the inspection device, and the measurement electrodes 16a and 16b are switched in a predetermined order. Enable either selectively. As a result, the AC voltage from the oscillation circuit 21 is applied to the activated measurement electrode 16a or 16b, and the electrostatic capacitance C is applied between the measurement electrode 16a or 16b and the package side electrode 15. A corresponding current will flow. Then, a voltage corresponding to the current value is output from the capacitance measuring circuit 20, and the electrostatic capacitances cα and cβ are calculated by the arithmetic processing circuit 32 based on the voltage, and further based on the electrostatic capacitances cα and cβ. Then, as described above, the “deviation amount” x and the “floating amount” d of each IC lead 12 are calculated and compared with the reference value. Then, in this embodiment, the "deviation amount" for a part of the IC lead 12 group
If x and “float amount” d exceed the reference value, I
Arithmetic processing circuit 3 assuming that the C lead 12 has a bending deformation
The number of the IC lead 12 is stored based on the signal from the IC 2 and the IC 13 is excluded by an ejection mechanism (not shown).

However, if most of the IC leads 12 have the same degree of "deviation" in the same direction, it is considered that this is due to the positioning error of the mount mechanism.
The pass / fail judgment is performed by ignoring the “deviation amount”. Therefore, even if the mounting mechanism sets the IC 13 at a position deviated from the centers of the electrodes 16a and 16b, the IC lead 12 will not be erroneously determined to have a bending deformation, and the malfunction can be reliably prevented. It

As described above, the present embodiment has the following effects. The mechanical structure portion for inspecting the IC is only the inspection substrate 14 on which a large number of electrodes are formed, and the inspection portion is different from the conventional optical inspection device in which the line light source and the line sensor need to be combined in an opposed state. Can be remarkably miniaturized. Of course, the mechanical portion is simple and the size can be reduced as compared with the configuration in which the optical displacement sensor is mechanically moved by the feeding mechanism. The miniaturization of the inspection unit in this way means that it can be easily incorporated into the component mounting robot, which is a remarkable advantage. Further, in this embodiment, the group of IC leads 12 is inspected one by one, but for this purpose, each switch element 22a of the selection circuit 22 is sequentially switched to each measurement electrode 16.
Since it is sufficient to sequentially activate a and 16b, the switching can be performed at an extremely high speed, and the time required for the inspection is greatly reduced as compared with the conventional configuration in which the IC lead groups are mechanically scanned one by one. Can be converted.

Further, generally, the purpose of this kind of inspection is to inspect the bending deformation of the IC leads which causes defective soldering to the printed circuit board. Therefore, it is ideal that the IC be inspected in the soldered state. For example, depending on the direction of bending deformation, even if the amount of bending deformation is relatively large in the state of floating in the air, when it is mounted on the printed circuit board, the weight of the IC causes the IC
This is because the bending deformation of the leads may be repaired and the leads may adhere to the lands of the printed circuit board. However, in the conventional optical inspection device, the IC was measured in a state of floating in the air unlike the state of soldering. On the other hand, according to the inspection apparatus of the present embodiment, the IC is inspected while being mounted on the inspection board 14. Therefore, the group of IC leads 12 is measured in the same state as when soldering, so that the degree of bending deformation can be accurately measured.
It will best suit the purpose of the inspection.

Further, in the present invention, since the "deviation amount" x and the "floating amount" d can be detected separately for the position of the tip of the IC lead 12, the IC 13 can be properly regulated due to the positioning error of the mounting mechanism. It is possible to reliably prevent the IC lead 12 from being erroneously determined to have a bending deformation when the IC lead 12 is set on the inspection substrate 14 with a slight deviation from the position.

In particular, in this embodiment, the package side electrode 15 is provided on the inspection substrate 14 and the package side electrode 1 is provided.
5, the capacitances Cα and Cβ are measured based on the capacitance C between the measurement electrode 16a and the measurement electrode 16a or 16b.
Cβ can be measured, and the configuration for capacity measurement is simplified.

Further, particularly in this embodiment, since the measurement electrode 16a or 16b which is not activated in the selection circuit 22 is grounded, the leakage current through the input-output capacitance can be minimized, The measurement error can be reduced accordingly.

<Other Embodiments> The present invention is not limited to the above-described embodiments, but can be modified and implemented as follows, for example.

(A) Various kinds of electronic parts can be applied as the electronic parts for inspecting the leads. For example, as shown in FIG. 8, a PLCC in which a large number of leads 62 are arranged in a rectangular package 61 having a recess 61a in the center. It may be applied to the lead inspection of the socket, and the point is that it can be widely applied to electronic parts in which leads are taken out from the package.

(B) In order to measure the electrostatic capacitance between the lead and the measuring electrode, it is not always necessary to provide the package side electrode 15 as in the first embodiment. A configuration may be used in which the capacitance between the electrode and the measurement electrode is measured. Further, even when the package side electrode is provided, it is not always necessary to provide it on the inspection substrate as in the above-mentioned embodiment, and it may be provided on the suction device side of the mount mechanism, for example.

(C) In the above embodiment, one oscillator circuit 21 is used.
Only the voltage is applied to each of the measurement electrodes 16a and 16b by providing only the measurement electrodes, but an oscillation circuit is provided for each measurement electrode and these oscillation circuits are selectively activated by a multiplexer. Good.

(D) In the above-mentioned embodiment, the example in which the invention is applied to the device for detecting the position of the tip of the IC lead and inspecting the bending of the lead is shown. However, the conductor position detecting method according to the present invention is lead inspection. Not limited to the device, it can be widely applied to a device that detects the position of a conductor by using a change in capacitance.

[Brief description of drawings]

FIG. 1 is a view for explaining a lead inspection apparatus of the present invention in comparison with other configurations, (A) is a front view, and (B) is a graph of capacitance.

FIG. 2 is a schematic diagram for explaining a position detection method of the present invention.

FIG. 3 is a block diagram schematically showing an embodiment of the present invention.

FIG. 4 is an enlarged perspective view of an electrode portion of the embodiment.

FIG. 5 is an overall block diagram of an embodiment.

FIG. 6 is an equivalent circuit diagram showing capacitance.

FIG. 7 is a sectional view of an electrode portion.

FIG. 8 is a cross-sectional view showing a PLCC socket as an inspection target.

[Explanation of symbols]

11 ... IC package 12 ... IC lead 14 ... Inspection board 15 ... Package side electrode 16a, 16b ... Measuring electrodes 17 ... Insulating film 20 ... Capacity measuring circuit 30 ... State determination circuit

Continuation of front page (56) Reference JP-A-3-27545 (JP, A) JP-A-4-242949 (JP, A) JP-A-4-311054 (JP, A) JP-A 64-5104 (JP , A) JP 59-214702 (JP, A) JP 63-86540 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/66 G01B 7/00 G01B 7/28 H01L 23/50

Claims (3)

(57) [Claims] 1. A method for measuring a capacitance between a measuring electrode and a conductor located in the vicinity of the measuring electrode to detect a displacement amount and a facing distance of the conductor with respect to the measuring electrode. And a pair of measuring electrodes are provided so as to be opposed to the conductor, and at least one of the measuring electrodes is the conductor.
Two capacitances between each of the measurement electrodes and the conductor are measured through an insulating film formed to cover the side, and the displacement of the conductor with respect to the measurement electrode is measured based on each capacitance. A method for detecting the position of a conductor, which comprises calculating an amount and a facing distance. 2. An electronic component to be inspected is placed at a predetermined position on an inspection board to inspect bending deformation of leads led out from the electronic component, the electronic part being provided on the inspection board. A pair of measurement electrodes facing the leads led out from the package of the electronic component, an insulating film formed on the inspection substrate to cover each of the measurement electrodes, and the lead forming the insulating film on each of the measurement electrodes. Capacitance measuring means for measuring each capacitance between the lead and each of the measurement electrodes in a state of being opposed to each other with respect to the measurement electrode of the lead based on each of the measured capacitances. A lead inspection device for an electronic component, comprising: a state determination unit that calculates a shift amount and a floating amount. 3. An inspection board is provided with a package side electrode corresponding to a package of an electronic component, and an electrostatic capacitance between the lead and the measurement electrode is set to an electrostatic capacitance between the package side electrode and each of the measurement electrodes. The lead inspection device for an electronic component according to claim 2, wherein the measurement is performed based on the capacitance.