JP3098635B2 - Shape inspection method and shape 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 shape inspection method and a shape inspection apparatus, and more particularly to a method for determining whether a shape of a conductor to be inspected formed of a conductor is good or not. The present invention relates to a shape inspection method and a shape inspection device that are determined by obtaining capacitance.

[0002]

2. Description of the Related Art Conventionally, for example, a shape inspection apparatus employing a computer image processing technique has been used for a lead frame shape inspection. The shape inspection apparatus stores a CCD camera that creates voltage data for each pixel constituting an image of a lead frame, and an inspection pattern as digital data obtained by thresholding the voltage data with a predetermined voltage value. And a CPU for storing a reference pattern, which is an image of an ideal lead frame, and a CPU. With this configuration, the CPU controls the CCD camera to generate voltage data, performs threshold processing on the voltage data, stores the voltage data as an inspection pattern on the RAM, temporarily transfers the reference pattern from the ROM to the RAM, and then stores the reference pattern in the RAM. The inspection pattern and the reference pattern are superimposed on the virtual plane provided in, and when both patterns coincide, it is determined that the product is good.

[0003]

However, a shape inspection apparatus employing the above-described computer image processing technique is a
The CPU performs threshold processing on voltage data for each of a large number of pixels constituting an image, moves a large number of pixels on an imaginary plane in a RAM to move an inspection pattern, and determines whether or not the pattern matches a reference pattern. In this case, it is necessary to make a determination for each pixel, and it takes a long time to determine the quality. Further, there is a problem that the quality of the shape in the height direction cannot be determined only by determining the quality of the planar shape. Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide a shape inspection method capable of determining in a short time the quality of a planar shape and a shape in a height direction of an inspected conductor formed of a conductor. An object of the present invention is to provide a shape inspection device.

[0004]

The present invention has the following arrangement to achieve the above object. In other words, the shape inspection method according to claim 1 includes a conductor to be inspected formed of a conductor and a reference conductor formed of a conductor and formed into a reference shape that is an ideal shape of the conductor to be inspected. together with a predetermined distance apart, oppositely disposed, wherein by applying a predetermined AC voltage between said reference conductor and the inspection conductor, measuring an electrostatic capacitance value between the inspection conductor and the reference conductor and, the electrostatic capacitance value, measured in advance in the reference conductor and the shape inspection conductor
It is characterized in that it is compared with a reference capacitance value or a reference capacitance range, and based on the comparison result, the quality of the shape of the conductor to be inspected is determined. In addition, the reference conductor is divided into a plurality of reference conductor components, each said reference conductor components, to measure the capacitance value between the inspection conductor <br/>, the capacitance value , in advance based on
Comparison with the reference capacitance value or the reference capacitance range set for each quasi-conductor component, and based on the comparison result, the shape of the portion of the inspected conductor corresponding to each reference conductor component May be determined.

According to a third aspect of the present invention, there is provided a shape inspecting apparatus, wherein a conductor to be inspected formed of a conductor and a reference shape which is an ideal shape of the conductor to be inspected are formed by the conductor. a reference conductor with a predetermined distance therebetween, and arranging means for arranging opposite said voltage applying means for applying a predetermined AC voltage between the inspection conductor and the reference conductor, the said inspection conductor criteria Measure the capacitance value with the conductor .
The capacitance measuring means, the conductor to be inspected having the same shape as the reference conductor, and the reference conductor are spaced apart from each other by the predetermined distance and arranged to face each other, and the predetermined AC voltage is applied to the conductor to be inspected. > And the reference capacitance between them when applied between them
Storage means for storing in advance a value or a reference capacitance range;
The capacitance value measured by the capacitance measuring means,
A comparing unit that compares the reference capacitance value or the reference capacitance range stored in the storage unit, and a determining unit that determines whether the shape of the conductor to be inspected is good or bad based on a comparison result compared by the comparing unit. It is characterized by having. Further, the reference conductor is divided into a plurality of reference conductor constituent parts, and the capacitance measuring means measures a capacitance value between the reference conductor constituent part and the conductor to be inspected. , the comparison means includes a static Den'yo
The amount value is compared with <br/> reference capacitance value or reference capacitance range of the reference conductor components for each stored by the storage means, the determining means, each reference on the basis of the comparison result of the comparing means Judgment of the shape of the conductor to be inspected corresponding to the conductor component
It may be a thing .

[0006]

In a case where a part of the conductor to be inspected which is spaced apart from the reference conductor by a predetermined distance and has a planar shape abnormality or an irregularity in the height direction has a problem, a gap between the reference conductor and the inspected conductor is caused. Since the capacitance value changes, the quality of the shape of the conductor to be inspected can be determined by comparing with a reference capacitance value measured in advance. In addition, the reference conductor is divided into a plurality of reference conductor components, and the capacitance value between the reference conductor component and the conductor to be inspected is measured. By comparing with a reference capacitance value or a reference capacitance range set for each part, the quality of the shape of the conductor to be inspected corresponding to the reference conductor constituting part can be determined based on the comparison result.

[0007]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. First, the configuration of the apparatus of the present embodiment will be described with reference to FIGS. The shape inspection apparatus according to the present embodiment is an apparatus for inspecting the shape of a lead frame which is an example of an object to be inspected. 10 is a shape inspection device,
It is for inspecting the shape of the lead frame 12 as a conductor to be inspected formed of a metal as a conductor,
The shape inspection apparatus 10 is configured to separate the lead frame 12 by a predetermined distance from a reference conductor 14 formed of a metal as a conductor and formed in a reference shape that is an ideal shape of the lead frame 12. , it is placed so as to face
Placement means 16 that, the lead frame 12 and the reference conductor 14
An AC power supply 18 as a voltage applying means for applying a predetermined AC voltage between the lead frame 12 and the reference conductor 14.
An analog switch 20, a peak hold circuit 22, and a capacitance measuring means for measuring a capacitance value between
A / D (analog / digital) converter 24 and C
PU 26, RAM 28 as storage means for storing the measured capacitance value, operating system of CPU 26, control program, control data, and reference capacitance between each reference conductor component and non-defective lead frame 12. A ROM 30 storing reference data and the like including a value and a reference capacitance range for pass / fail judgment, and a display device 32 connected to the CPU 26 for displaying the judgment result
It is composed of Further, the CPU 26 also serves as comparing means for comparing the measured capacitance value with the reference capacitance value, and as determining means for determining whether the shape of the lead frame 12 is good or bad based on the comparison result. ing. here
In the reference capacitance value or reference capacitance range, first,
Make the conductor under test an ideal shape, that is, an ideal test
Form the conductor into the same shape as the reference conductor.
It is placed at a predetermined distance from the body and opposed to the body. So
And apply a predetermined AC voltage between the conductor under test and the reference conductor.
To obtain the capacitance value between the two
Measurement. The arranging unit 16 strictly places the lead frame 12 on the reference conductor 14 by using a guide hole 36 of the lead frame 12 by a guide mechanism (not shown) after the lead frame 12 is transported by the roller 34 in the direction of the arrow A. This is to perform a proper alignment.

The reference conductor 14 is connected to the lead frame 1.
Each of the two pins 38 (20 pins in the present embodiment) and a stage 40 on which a chip of an integrated circuit divided into four is mounted are divided into 24 reference conductor components. Each of the reference conductor components has a resistor 42 between itself and the ground.
(Resistance value: constant) is connected, and voltages V1 to V24 generated between the resistors 42 and the ground (V1 to V20 correspond to the pins 38 of the reference conductor 14, and V21 to V24 are 4
(Corresponding to the divided stage 40) is input to the analog switch 20 through the buffer 42. In addition,
The reference conductor 14 is connected to the lead frame 12 via an insulator 43 having a certain thickness such as a PET film.
When the capacitance value is measured, the lead frame 12 conveyed by the arranging means 16 is spaced apart by a predetermined distance and arranged to face each other. As a result, the increase / decrease of the capacitance values of the capacitors C1 to C24 formed between each of the reference conductor constituting portions and the lead frame 12 appears as an increase / decrease of the inter-resistance voltages V1 to V24. Therefore, the lead frame 12
When there is an abnormality in the planar direction, the area of opposition to the reference conductor constituting part is reduced, so that the capacitance is reduced. Since the distance between the lead frame 12 and the conductor component is increased, the capacitance is reduced, and the abnormality of the lead frame 12 can be determined by inspecting the values of the voltages V1 to V24 between the resistors.

Next, the operation of the shape inspection apparatus having the above configuration will be described with reference to FIGS. In addition,
It is assumed that only one unit of 11 pins of the lead frame 12 to be inspected has an abnormality. When power is turned on, CPU2
When the CPU 6 starts up, the CPU 26 reads a control program and the like from the ROM 30 and clears the contents of the RAM 28 (step 100). Next, the arranging means 16 is controlled so that one unit of the lead frame 12 to be inspected is
It is positioned and arranged above (step 102). Subsequently, an AC voltage is applied from the AC power supply 18 to the lead frame 12 (step 104), and the inter-resistance voltages V1 to V24 of the respective reference conductor components input to the analog switch 20 via the buffer 42 are sequentially analog-converted. By switching the switch 20, the signal is sent to the peak hold circuit 22,
A peak value of a voltage between resistors within a predetermined period is detected. Further, this peak value is, for example, a 12-bit A / D converter 2
4, the data is converted into digital data, and is taken into the CPU 26 via the I / O interface 44 (step 106). The CPU 26 stores the digital data in the RAM 28 as a capacitance value (step 108). . At this time, the CPU 26 obtains a capacitance value based on the received digital data, and may store this capacitance value in the RAM 28. However, as described above, the inter-resistance voltages V1 to V24 are Since the data changes according to the capacitance value, it is sufficient to treat the digital data as a capacitance value.

The CPU 26 outputs a switching signal to switch the analog switch 20, and after storing the capacitance values between all the reference conductor constituting portions and the lead frame 12, the CPU 26 outputs R.
The capacitance value stored in the AM 28 is compared with the reference capacitance value and the reference capacitance range stored in the ROM 30 (step 110), and the measured capacitance value becomes the reference capacitance value. On the other hand, if it is within the reference capacitance range, it is determined that there is no abnormality in the portion corresponding to the reference conductor configuration portion of the lead frame 12, and the capacitance value is compared with the reference capacitance value and is abnormal. When it is out of the reference capacitance range, it is determined that there is an abnormality, and the corresponding reference conductor component is displayed on the display device 32 (step 11).
2). In the present embodiment, the pin 11 of the lead frame 12 has an abnormality (an abnormality in the height direction due to bending of the pin).
As an example, the pin numbers of the 11 pins are displayed. Actually, the measured capacitance value is graphed (FIG. 4B), and compared with the graph of the reference capacitance value (FIG. 4A), the measured capacitance value of the 11th pin is the reference static value. It can be seen that the value is significantly lower than the capacitance value (arrow B). When the comparison of all the reference conductor components is completed, the process returns to step 102 again in order to inspect the next one unit of the lead frame 12. In this way, by repeating the above-described steps, it is possible to continuously inspect for irregularities in the shape of the lead frame 12 (surface irregularities due to warpage, rust, dirt, etc.).

Using a plurality of the above-described shape inspection devices 10, the reference conductors 14 are arranged at regular intervals d in a direction C perpendicular to the moving direction A of the lead frame 12, as shown in FIG. (FIG. 5 shows a case where there are two reference conductors 14). When this structure is adopted, even if the lead frame 12 is displaced in the direction C at the time of conveyance, it coincides with one of the reference conductors 14 arranged at regular intervals d. By measuring the capacitance value between each reference conductor component and the lead frame 12 at a high speed, the lead frame 12 can be transported without strictly positioning it using a guide mechanism. Inspections of one unit of shape can be inspected. In addition, although the inspection accuracy is slightly reduced, the reference conductor 14 is not divided into the respective reference conductor components, and the ideal lead frame 1 is not divided.
Alternatively, the shape inspection device may be configured to have the same shape as one of the two units and omit the analog switch 20. However, in this case, since the amount of data to be processed is reduced, a higher-speed inspection can be performed. The reference capacitance value is stored in the ROM 3 in advance.
Instead of storing the value in 0, the reference capacitance value may be obtained from a lead frame having an ideal shape and stored in the RAM 28 during the preparation (step 100) in FIG. In addition, when the shape inspection device is used, the resonance frequency of the conductor, the degree of inclination between the conductor and the reference conductor, and the degree of rotation of the conductor are determined from the capacitance value between the conductor having a planar shape and the reference conductor. It is also possible to measure.

As described above, various preferred embodiments of the present invention have been described. However, the present invention is not limited to the above-described embodiments, and many modifications can be made without departing from the spirit of the invention. Of course.

[0013]

When the shape inspection method and the shape inspection apparatus according to the present invention are used, the inspection target is separated from the reference conductor by a predetermined distance and the capacitance value between the inspection target conductor opposed to the reference conductor is determined. Since the quality of the conductor can be determined, it is possible to inspect not only the planar shape of the conductor to be inspected but also the shape in the height direction. Further, the reference conductor is divided into a plurality of reference conductor constituent parts, and a capacitance value between the reference conductor constituent part and the conductor to be inspected is measured. Reference capacitance value set for each unit,
Alternatively, a higher-precision inspection can be performed by comparing with a reference capacitance range and determining whether or not the shape of the portion of the conductor to be inspected corresponding to the reference conductor constituting portion is good or bad based on the comparison result. Further, unlike the related art, there is no need to perform pattern matching by image processing, and it is not necessary to process a huge amount of pixel data, so that a high-speed inspection can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a shape inspection apparatus according to the present invention.

FIG. 2 is an enlarged view showing a relationship between a reference conductor of the shape inspection apparatus of FIG. 1 and one unit of a lead frame.

FIG. 3 is a flowchart showing the operation of the apparatus according to the embodiment.

FIG. 4A is a graph showing reference capacitance value data stored in the shape inspection apparatus of FIG. 1, and FIG.
Is a graph showing capacitance value data measured by the shape inspection apparatus in FIG. 1, the vertical axis shows the magnitude of digital data (12 bits) of the voltage between resistors taken in by the CPU, and the horizontal axis shows 3 shows a reference conductor configuration.

FIG. 5 is an enlarged view showing a relationship between a reference conductor and one unit of a lead frame in another embodiment of the shape inspection apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Shape inspection apparatus 12 Lead frame 14 Reference conductor 16 Arrangement means 18 AC power supply 20 Analog switch 22 Peak hold circuit 24 A / D converter 26 CPU 28 RAM 30 ROM

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) G01B ^7/ 00-7/34 102 H01L 21/64-21/66

Claims (4)

(57) [Claims] An inspection target conductor formed of a conductor and a reference conductor formed of a conductor and formed in a reference shape that is an ideal shape of the inspection target conductor are separated by a predetermined distance, oppositely disposed, wherein by applying a predetermined AC voltage between said reference conductor and the inspection conductor, to measure the capacitance value between the inspection conductor and the reference conductor, the electrostatic capacitance value The conductor to be inspected has the same shape as the reference conductor.
A shape inspection method characterized by comparing a reference capacitance value or a reference capacitance range measured in advance, and judging the shape of the conductor to be inspected based on the comparison result. Wherein said reference conductor is divided into a plurality of reference conductor components, each said reference conductor components, to measure the capacitance value between the inspection conductor, the electrostatic capacitance value, The reference capacitance value or the reference capacitance range set in advance for each reference conductor component is compared. Based on the comparison result, the test target corresponding to each reference conductor component is inspected.
The shape inspection method according to claim 1, wherein the quality of the shape of the conductor portion is determined. 3. A test conductor formed of a conductor and a reference conductor formed of a conductor and formed in a reference shape that is an ideal shape of the test conductor are separated by a predetermined distance, and arrangement means for arranging oppositely, the voltage applying means for applying a predetermined AC voltage between said reference conductor and the inspection conductor, the electrostatic capacitance value between the inspection conductor and the reference conductor the capacitance measuring means for measuring, and the object to be inspected conductor of the reference conductor and the same shape, with the <br/> said reference conductor spaced said predetermined distance, oppositely disposed, a predetermined AC voltage to be storage means for previously storing the reference electrostatic capacitance value or reference capacitance range therebetween when applied between the test conductor and the reference conductor, the capacitance value measured by the capacitance measuring means ,
Comparing means for comparing with a reference capacitance value or a reference capacitance range stored in the storage means ; and determining whether the shape of the conductor to be inspected is good or bad based on a comparison result compared by the comparing means. A shape inspection apparatus comprising: 4. The reference conductor is divided into a plurality of reference conductor components, and the capacitance measuring means is configured to be inspected for each reference conductor component.
The capacitance value between the conductor and the conductor is measured, and the comparing means stores the capacitance value by the storage means.
Compared to the reference electrostatic capacitance value or reference capacitance range of the reference conductor arrangement portion each which, the determining means, the portions of the inspected conductors corresponding to each reference conductor components on the basis of the comparison result of the comparing means shape inspection apparatus according to claim 3, characterized in that determining the acceptability of the shape.