JPH0771920A - Method for inspecting mounted state of electronic part - Google Patents

Abstract

PURPOSE:To provide a method capable of quickly and precisely judging whether an electronic part is loaded on a base in a normal posture or not. CONSTITUTION:The heights of a plurality of measuring points (a), (b), (c), (d) in an area in which the presence of an electronic part 2 on a base is predicted are measured by a height measuring device, and the measurement values are compared with a set value based on the thickness of the electronic part 2 to judge the quality of the mounted state. Since all the measurement values are values approximate to the thickness of the electronic part 2 when the mounted state of the electronic part 2 is normal, the quality can be precisely judged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of inspecting a mounting state of an electronic component for determining whether the electronic component is normally mounted at a predetermined position on a board.

[0002]

2. Description of the Related Art An electronic component mounting apparatus mounts an electronic component on a substrate and then inspects whether the electronic component is properly mounted. The inspection items are (1)
Whether the displacement of the electronic components is within the allowable value, (2)
The presence / absence of an electronic component at a predetermined position on the board, (3) whether the electronic component is not standing, and the like are included.

Conventionally, a camera has been used as an inspection device for inspecting the mounting state of electronic components. As an inspection method using a camera, first, as described in, for example, Japanese Patent Laid-Open No. 3-15708, a substrate on which an electronic component is mounted is observed from directly above, and bright and dark image data is captured.
A method is known in which a difference in brightness between an electronic component and a substrate is analyzed by a CPU of a computer or the like to determine the positional deviation or presence / absence of the electronic component.

Second, for example, Japanese Unexamined Patent Publication No. 3-9249.
As described in the publication, a method using a light section line is known. This method irradiates the electronic components on the substrate with a plurality of slit lights obliquely from above and observes the reflected light of the slit lights with an upper camera, and based on the position of the discontinuity point of the light cutting line, It is for determining the positional deviation and presence / absence of parts.

[0005]

However, the above-mentioned first problem
The method (1) has a problem that the inspection cannot be performed when there is not much difference between the brightness of the electronic component and the brightness of the substrate. In the second method, a plurality of projectors for irradiating slit light are required, resulting in an increase in size of the apparatus, and image data of the light cutting line is temporarily stored in a memory, and the image data is stored in various ways. It is necessary to detect the discontinuity point of the optical cutting line by processing using an algorithm, and further to break the position of this discontinuity point to judge the misalignment and presence of electronic parts. However, since it takes a considerable amount of time, there is a problem that a quick inspection cannot be performed.

Further, in the method of taking image data into a camera and performing image processing, it is inevitable that the brightness of the image flickers due to fluctuations in the brightness of the illumination light and the like. There is a problem that it is extremely difficult to perform software processing of a computer and adjustment of illumination light in order to eliminate erroneous determination due to.

It is therefore an object of the present invention to provide a method of inspecting the mounting state of electronic components, which can accurately inspect the displacement, presence / absence, and standing of electronic components at high speed without using a camera.

[0008]

To this end, according to the present invention, heights of a plurality of measurement points in an area where electronic parts are expected to exist on a substrate are measured by height measuring means, and measured values are electronically measured. By comparing with a set value based on the thickness of the component, the quality of the mounted state can be accurately determined.

[0009]

According to the above construction, it is possible to accurately judge the quality of the mounting state of the electronic component by a simple process of measuring the heights of a plurality of measurement points and comparing the measured value with the set value.

[0010]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a front view of an inspection device for electronic parts. An electronic component 2 is mounted on the board 1. The electrode 3 of the electronic component 2 is soldered to the electrode 4 of the substrate 1 with the solder 5.

The substrate 1 is placed on the moving table 6. The moving table 6 includes an X table 7 and a Y table 8. When the motor 9 of the X table 7 is driven, the substrate 1 horizontally moves in the X direction, and when the motor 10 of the Y table 8 is driven, the substrate 1 horizontally moves in the Y direction.

A height measuring device 11 is provided above the moving table 6. The height measuring device 11 includes a laser oscillator 12 that vertically irradiates the substrate 1 with laser light, and a light receiving unit 13 that receives the laser light reflected by the substrate 1 and the electronic component 2. The light receiving unit 13 includes a condenser lens 14 and a light receiving element 15. From the position of the laser light incident on the light receiving element 15, the height measuring device 11
The height of the reflection point of the laser light, that is, the measurement point is measured. The measurement data of the light receiving unit 13 is the control unit 1
Sent to 6. The control unit 16 includes a CPU, a memory, a calculation unit, and the like, and determines the position shift, presence / absence, and standing of the electronic component 2 from the height of the measurement point, as described later.

Next, a method for determining whether the electronic component is mounted or not mounted will be described. FIG. 2 is a plan view showing measurement points. In the figure, A is an area where the electronic component 2 between the electrodes 4 is expected to exist. The planar shape of the electronic component 2 of this embodiment is a quadrangle, and this area A is the same as the outer shape of the electronic component 2. Reference characters a, b, c, and d are measurement points set at four corners in the area A. The measurement points a, b, c and d are at a distance Δ from the corner of the area A.
Only X and ΔY are set inward. ΔX is an allowable value of positional deviation of the electronic component in the X direction, and ΔY is an allowable value of positional deviation of the electronic component in the Y direction. The permissible values ΔX and ΔY are determined based on the size of electronic components, required mounting accuracy, and the like.

3A and 3B and FIGS. 4A and 4B.
[FIG. 4] is an explanatory diagram of a determination method. In each drawing, the left drawing is a plan view near the electrode 4, and the right drawing is a perspective view near the electrode 4. In FIG. 3A, when the mounted state of the electronic component 2 is normal, the four measurement points a, b, c, d are present at the four corners of the upper surface of the electronic component 2. The heights H of all the measurement points a, b, c, d satisfy the following equation.

0.9h <H <1.1h (1) where h is the thickness of the electronic component 2. Further, 0.9 and 1.1 are coefficients set based on variations in the thickness h of the electronic component 2 and the like. The thickness h and the coefficient are determined by the control unit 1.
6 is registered in advance in the memory.

FIG. 3B shows a case where the electronic component 2 is displaced. In this case, four measurement points a, b,
Of c and d, at least one measurement point (measurement point c in this embodiment) is not on the upper surface of the electronic component 2,
Since it is on the upper surface of the substrate 1, the height H of this measurement point c
Satisfies the following equation.

0.9h> H ... (2) FIG. 4A shows the case where the electronic component 2 is not provided. In this case, the four measurement points a, b, c, d are all on the substrate 1
Above, these heights H all satisfy the following equation:

0.9h> H (3) FIG. 4B shows the case where the electronic component 2 is standing. In this case, of the four measurement points a, b, c, d, the height of at least one measurement point (measurement points c, d in this embodiment) satisfies the following equation.

1.1h <H (4) Therefore, by determining which of the above four conditions is satisfied, it is determined whether the electronic component 2 is normal, misaligned, absent, or standing. be able to. This determination is performed by the CPU provided in the control unit 16.

Next, the determination method will be described with reference to the flowchart of FIG. In FIG. 1, the moving table 6 is driven to position the electronic component 2 directly below the laser oscillator 12, and the laser light is radiated toward the electronic component 2 so that the electronic component 2 is expected to exist in the area A. The height H of the four measurement points a, b, c, d is measured (step 1).

Next, in step 2, it is judged whether or not the heights H of the four measurement points a, b, c, d are all larger than 0.9h and smaller than 1.1h, and Ye
If s, it is determined to be normal (step 7), and if No, it is determined to be defective. Next, in step 3, it is determined whether or not the height H is greater than 1.1h among the four measurement points a, b, c, d. If Yes, it is determined to be standing (step 8). If No, the process proceeds to step 4, and it is determined whether or not the heights H of the four measurement points are all less than 0.9h. If Yes, it is determined that there is no electronic component 2 (step 9). If No, the process proceeds to step 5, and it is determined whether or not the height H of the four measurement points a, b, c, d is larger than 0.9h and smaller than 1.1h. If Yes, it is determined that the position is displaced (step 10). On the other hand, if No, it is determined that there is some abnormality other than standing, none, and positional deviation (step 6). This abnormality is, for example, a case where different types of electronic components are mounted in the area A.

When judging the mounting state of electronic parts,
In many cases, it is not necessary to determine only the defect and determine the content of the defect, that is, which of the defect items such as misalignment, absence, and standing. In this case, in step 2 described above, it suffices to determine only good or bad.

[0024]

As described above, according to the present invention, heights of a plurality of measurement points in an area where electronic components are expected to exist on a substrate are measured by a height measuring device, and measured values are electronically measured. By a simple method of comparing with a set value based on the thickness of the component, it is possible to quickly and accurately determine whether the mounting state of the electronic component is good or bad.

[Brief description of drawings]

FIG. 1 is a front view of an inspection apparatus for an electronic component mounting state according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an inspection method for a mounting state of electronic components according to an embodiment of the present invention.

FIG. 3 (a) is an explanatory diagram of an inspection method of an electronic component mounting state according to an embodiment of the present invention. (B) An explanatory diagram of an electronic component mounting state inspection method according to an embodiment of the present invention.

FIG. 4A is an explanatory diagram of an inspection method of an electronic component mounting state according to an embodiment of the present invention. FIG. 4B is an explanatory diagram of an electronic component mounting state inspection method according to an embodiment of the present invention.

FIG. 5 is a flowchart of a method for inspecting a mounting state of electronic components according to an embodiment of the present invention.

[Explanation of reference numerals] 1 substrate 2 electronic component 11 height measuring device 12 laser oscillator 13 light receiving unit

Claims (3)

[Claims] 1. The height of a plurality of measurement points in an area where an electronic component is expected to exist on a substrate is measured by height measuring means, and the measured value is compared with a set value based on the thickness of the electronic component. Accordingly, a method for inspecting the mounting state of electronic components is characterized by determining the quality of the mounting state. 2. The plane shape of the electronic component is a quadrangle,
The method for inspecting a mounting state of an electronic component according to claim 1, wherein the measurement points are set at four corners of the upper surface of the electronic component. 3. The height measuring means comprises a laser oscillator and a light receiving unit for receiving laser light emitted from the laser oscillator and reflected by an object to be measured. Inspection method of mounting condition of electronic parts.