JPH0377051A - Chip component inspection device - Google Patents

Abstract

PURPOSE:To analyze the symmetry of a variable density profile on each segment and decide a chip position shift by comparing variable density profiles on respective segments at center positions with the density value of a folded place by utilizing the symmetry of the variable density profiles on the respective segments. CONSTITUTION:A chip component 10 to be inspected has electrode parts 12 of right-left symmetrical size in an X-axis direction and is horizontally and vertically symmetrical. Here, when the company 10 is mounted accurately at a specific position, variable density profiles gy, gxl, and gxgamma of density values of picture elements on a segment lx bisecting the component 10 into an upper and a lower part in a Y-axis direction, a segment Lyl bisecting the left electrode part into a right and a left part in the X-axis direction, and a segment lygamma bisecting the right electrode part into a right and a left part in the X-axis direction are found. Then, the variable density profile on the segment lx is symmetrical about the center of a picture element array, the variable density profile on the segment l yl is symmetrical about the center yM, and the vari able density profile on the segment lyl is symmetrical about the center yM. Then the symmetry of the light-shade profiles on the respective segments is utilized to compare the density value of the folded place and the symmetry is analyzed to decide the position shift.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a chip component inspection device, and particularly to a chip component inspection device that can inspect whether chip components are accurately mounted in a predetermined position without misalignment in the appearance inspection of a mounting method board. Related to parts inspection equipment.

[Conventional technology]

As a conventional technique, for example, Japanese Patent Application Laid-Open No. 60-231400
There is an inspection device as shown in the publication.

A conventional chip component inspection apparatus includes a test object mounting table and at least two test objects mounted on the test object mounting table.
The apparatus includes an illumination means for emitting light from a direction, a photographing means disposed on the inspection object mounting table, and a comparison processing means for comparing contrast information obtained by the photographing means.

Next, a conventional chip component inspection method will be described in detail with reference to the drawings.

FIG. 9 is a perspective view showing a conventional example, FIG. 10 is a histogram showing details of the comparison means shown in FIG. 9, and FIG.
9a) and 9(b) are a side view and a plan view showing details of the chip component shown in FIG. 9;

As shown in FIG. 9, a printed circuit board 15 on which a chip component 14, which is an object to be inspected, is attached is fixed to an object to be inspected mounting table 13, and a predetermined light 17 is spot-irradiated onto the chip component 14 from diagonally above in four directions. do.

The chip component 1 is photographed by an ITV camera 18 and a comparison means 19 comprising a computer.
As shown in FIG. 10, the mantrast information of 4 and the standard contrast information of the chip component 140 at the proper position stored in advance are processed into an X-direction density histogram and an X-direction density histogram. It can be determined whether the chip component 14 is correctly placed in a fixed position.

The X-direction density histogram and the X-direction density histogram shown in FIG. 10 are based on the pattern image in the area surrounded by cursor A, that is, the reflected light from the chip component 14 and the cream solder land (pad) 16 shown in FIG. 11(a). It is obtained by analyzing the X-direction component and Y-direction component of the pattern image B to be formed, and the protruding constant width portion 12 In A shown in both of these gray scale histograms.
' 2r 423t (4 is the ITV shown in Figure 11(b)
Upper margin Lll and lower margin L2 of the chip component with respect to the cream solder land (pad) shown in the plan view of the chip component 14 and cream solder land (pad) 16 seen from the camera 18 side. Left side margin 1. This data corresponds to the right side margin L4, and 1 obtained from the histogram.
By comparing the range of 1 to 14 with standard data,
It is determined whether the chip component 14 is in the normal position.

[Problem to be solved by the invention]

The conventional chip component inspection apparatus described above compares the X-direction density histogram obtained from an image of the chip component with a spot light and the density histogram of the chip component as a reference to determine whether the chip component is in the correct position. Since it is judged whether the density histogram is Il, which should be caused by the boundary between the chip component and the cream solder land (pad) due to the influence of surrounding electronic components and the difference in light reflection due to the solder shape, i
A problem arose in which the protruding portion of a constant width that determines the width of the chip cannot be stably obtained. The drawback was that it required adjustments to be made.

[Means for solving the problem]

A chip component inspection device of the present invention includes an ITV camera that images a chip component on a mounted board, an A/D converter that converts a video signal of the ITV camera into a digital signal, and a device that stores the digital signal as an image. an image memory, a CAD data memory in which CAD data related to a chip component to be inspected is stored in advance, and the CAD
a one-dimensional data extraction unit that uses data in a data memory to extract one-dimensional pixel string data on three line segments, which serve as basic data for inspection, from the image memory and creates gray profile data on each line segment; , a gray profile memory that stores the three gray profile data extracted by the one-dimensional data extraction unit, and a gray profile that is folded around the center point of each of the data in the gray profile memory, and the gray values are superimposed and compared. a gradation symmetry analysis unit that analyzes the symmetry of the gradation profile; a counter that stores the analysis result of the gradation symmetry analysis unit as a count value; and mounting of chip components using the counter and the data in the CAD data memory. It is configured to include a determination unit that determines positional deviation.

[Principle and operation of the invention]

The principle of the inspection method of the chip component inspection apparatus of the present invention will be explained using the drawings.

FIG. 7 is a schematic diagram of three line segments used in the present invention and the shading profile on each line segment, and FIGS. 8(a) and (b).

(c) is a graph for explaining the symmetry of the shading profile on each line segment.

As shown in FIG. 7, the chip component 10 to be inspected is assumed to have electrode portions 12 that are symmetrically sized in the X-axis direction, and to be symmetrical laterally and vertically.

When the chip component 10 is accurately mounted in a predetermined position, a line segment 1 that divides the chip component 10 into upper and lower halves in the Y-axis direction
8. A line segment βa6 that divides the left electrode portion into left and right halves in the X-axis direction.
The shading profile g of the shading values of pixels on each line segment A yr that divides the right electrode part into left and right halves in the X-axis direction
If we take F+ gxrz gxr, they are the 8th respectively.
Line segment 1 as shown in Figures (a), (b), and (c)
For the gray scale profile above 8, the center XM of the pixel row
The shading profile on the line segment A is symmetrical at the center yM, and the shading profile on the line segment A yr is also symmetrical at the center yM.

Conversely, if the chip components are misaligned, this symmetry will shift.

In the present invention, by utilizing the symmetry of the shading profiles on each line segment, the shading profiles on each line segment are folded back and overlapped at the central position XMIyM shown in FIGS. 8(a), (b), and (c). This symmetry is analyzed by comparing the shading values at different locations to determine positional deviation.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

First, a video signal d of an image of a chip component to be inspected captured by the ITV camera 1 is converted into a digital signal e by the A/D converter 2 and stored in the image memory 3 as a digital image.

On the other hand, CAD of the chip parts to be inspected in advance
The data is stored in the CAD data memory 4.

FIG. 2 is a schematic diagram for explaining the data in the CAD data memory.

An X-Y coordinate system is set on the image plane, and the X-axis and Y-axis are the Xw-axis I of the xw-Yw coordinate system on the mounting board, respectively.
It is parallel to the Yv axis, and if the mounted chip component 10 is accurately mounted at a predetermined position, each side of the chip component 10 will be either perpendicular or parallel to the X axis and the Y axis.

The CAD data includes the X and Y coordinates (X1+)'M)#(Xrr) of the positions of the left and right electrode portions 12 of the chip component 13, which should be on the image plane calculated in advance.
'M) is determined by the set (X j s X r
tyM) and '[ in the X-axis direction and Y-axis direction of the chip component.
wx.

WY and the width W of the electrode section 12 in the X-axis direction! There is an I.

The above is the operation corresponding to the preprocessing stage of the present invention.

After the preprocessing, the one-dimensional data extraction unit 5 extracts the position data h1 of the set (X 1 r The data bs and ht of the chip width WY and the electrode width W8 are read, and a one-dimensional grayscale image is taken out from the image memory 3 to obtain grayscale pull file data that becomes basic data.

The operation of the one-dimensional data extraction unit 5 will be explained.

FIG. 3 shows three line segments n, , I2A5, generated in the one-dimensional data extractor 5. (A) It is a schematic diagram for explaining.

Here, the data read from the CAD data memory 4 (X j
Assuming 18 from the data of r
2) Calculate (1) and assume that X=xn, (7u Wy/2≦Y≦7M+WY/2)
Calculate (2), and as Ayr, X ” X * −+ ()' M Wy/2≦Y≦7
M+WY/2) Calculate (3).

The pixel row data on each of these line segments is shown in FIG. 4, which is a schematic diagram of the density profile on each line segment.
Corresponding to each density profile of pgxt, line segments 11, ,
Pixel column data q+y on II□+Lr (12# q3
are stored in separate areas of the gradation profile memory 6 as gradation profiles on each line segment.

Next, the shade symmetry analysis unit 7 uses the line segment l! from the shade profile memory 6! Upper gray profile data ql+flyJ
The gray profile data q3 on the gray profile q2 + II yr above are read in sequence, and the symmetry of each gray profile is analyzed.

The operation of the shading symmetry analysis unit 7 is shown in FIG. 5(a).

(b), (c) and Figure 6 (a), (b),
This will be explained using (c).

Figure 5 (a), (b), and (c) are each line segment I! 8. Line segment l21. Line segment n? ! It is a graph showing the density profile g y rgx□2g8 obtained above.

FIGS. 6(a), 6(b), and 6(c) are graphs for explaining the analysis operation of shading symmetry.

In the shading symmetry analysis unit 7, the read line segment l! Arrangement Xa of the upper gray profile data q1.

With respect to y, centering on the center y8 shown in FIG. 5(b), line segment lA, and centering on yM shown in FIG. 5(c) for the upper gray profile data q3, Analyze symmetry.

First, for the shading profile data on line segment i78,
As shown in Figure 6(a), the left side (XOrX
M) area profile R, on the right side (x, etc.).

Fold back and overlap the profile R7 of the area xfi),
Only the overlapped points with similar shading values are extracted.

FIG. 6(a) shows an example in which when points A, B, C, and D are superimposed, they are taken out as having similar shading values.

This operation is performed by changing i from 0 to M-1 using the following equation (4). If the equation (4) is satisfied, the counter 8 receives an output value r, = 1; otherwise, r1 = 0. This is achieved by outputting .

l gy (x+) gy (xfl-+) l
<Tt (4) T here! is a threshold value set in advance.

Similarly, line segment 11. For the gradation profile data on I, as shown in FIG. 6(b), the left region R6 and the right region R1 in FIG. 5(b) are overlapped with YM as the center and the gradation values are compared. , in the following equation (5), if i is varied from O to M-1 and satisfied, the output value r,=1 is output to the counter 8; otherwise, r2=0 is output to the counter 8.

l g, p (yr)-g, □(ym-1) l<'
rA (5) (T is a threshold value) E and F in FIG. 6(b) are an example showing points at which the output value r2=1 is output.

In addition, as shown in FIG. 6(C), the shading profile on the line segment lA is done in exactly the same way, with the region Ru on the left and the region Ri on the right in FIG. 5(c) centering on yM.
In order to extract the parts G and H whose gradation values are similar by superimposing them, change i from O to M-1 using the following equation (6), and if satisfied, output value r to counter 8, = 1, so Otherwise, outputs rs=o.

l gNr (71) gxr (7a+-1)
l <'r,, (6) (T2. is a threshold value) The counter 8 calculates the line segment l! Output value for line segment lA, output value for upper, output value for line segment lA, T1y r
It consists of three counters, respectively zt, rs, and each counter is incremented when the output value ri, r2z, r3 is "1", and is shown in FIGS. 6(a) and (b).
), A, B, C, D shown in (c).

The number of points (pixels) with similar gray values for E, F, G, and H is obtained as a result.

If each density profile has strong symmetry, each counter value will become large.

Finally, in the determination unit 9, the counter value Cx*C11t for each line segment of the counter 8, the count data U of CFr, and the chip 'swx from the CAD data memory 4.

Read WY and determine the chip mounting state.

In the determination unit 9, the counter values Ct # Cyj , Cyr of the counter data U read from the counter 8,
Depending on the chip width W, W, of the CAD data memory 4, if the following equations (7), (8), and (9) are satisfied at the same time, the result is normal, and if at least one of the equations is not satisfied, the judgment result is that the positioning is not possible. .

W, / 2 C, < T 1 (7) W, / 2 Cyt < T 2 (
8) W, /2 C,, <T2 (
9) Here, Tl and T2 are threshold values that are set in advance and serve as determination criteria.

〔Effect of the invention〕

The chip component inspection device of the present invention utilizes the symmetry of the shading profile instead of using the shading contrast information obtained from the shading histograms in the X and Y directions to determine the misalignment state of the chip component. conditions and surrounding electronic components.

It is possible to solve the problem of unstable inspection results due to reflection of light from the solder shape, etc.

Furthermore, since one-dimensional processing is performed using only the pixel row data on three line segments occurring in the X-axis direction and Y-axis direction, the image can be processed in two-dimensional terms as is with conventional technology. The effect is that high-speed processing can be achieved with a smaller amount of information compared to the previous method.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is an explanatory diagram of the coordinate system and data in the CAD data memory, and FIG.
The figure is an explanatory diagram of the line segment βxz Ryap Il rr, Figure 4 is a diagram of the relationship between the three line segments and the density profile, and Figure 5
Figures (a), (b), and (c) are each line segment I:
lx r line segment 4 yJ *line segment la, a graph showing the shading profile gy2g□1g8 obtained above, Figure 6 (a), (b), and (c) are the shading of the shading profile on the line segment, respectively. Symmetry analysis operation explanatory diagram, Figure 7 is a schematic diagram of three line segments and their shading profiles for detailed explanation of the present invention, Figure 8 (a), (b),
(c) is a schematic diagram for explaining the symmetry of the shading profile on each line segment, and FIG. 9 is a perspective view showing an example of the conventional method.
Figure 10 is a density histogram of the pattern shown in Figure 9;
FIGS. 11(a) and 11(b) are schematic imaging diagrams. 1...ITV camera, 2...A/D converter, 3...image memory, 4...CA
D data memory, 5... one-dimensional data extraction section,
6... Gray profile memory, 7...
- Shade symmetry analysis section, 8... Counter, 9...
... Judgment unit, 10... Chip parts, 11...
... Pad, 12 ... Electrode part, 13 ...
...Inspected object mounting table, 14...Chip parts,
15...Printed board, 16...Cream solder land (pad), 17...Spot light,
18... ITV camera, 19... Comparison means, d... Video image, e... Digital signal, hl... Chip position data, hl・・・・・・
Chip width in X-axis direction, h... Chip width in Y-axis direction, h4... Electrode width in X-axis direction, O... One-dimensional data extraction signal, pHP2. P3... One-dimensional pixel row data, q++ qz+ qs... Gray profile data, rlp r! + r3'・
... Grayscale analysis result, U ... Counter value data, ■ ... Judgment result.

Claims (1)

[Claims] A TV camera that images the chip components on the mounted board, and A that converts the video signal of the TV camera into a digital signal.
/D converter, an image memory that stores the digital signal as an image, and a C related to the chip component to be inspected.
Using a CAD data memory that stores AD data in advance and the data in the CAD data memory, one-dimensional pixel string data on three line segments, which will be the basic data for inspection, is extracted from the image memory and each line is a one-dimensional data extraction unit that creates gray profile data for each area; a gray profile memory that stores three gray profile data extracted by the one-dimensional data extraction unit; and a gray profile memory that stores three gray profile data extracted by the one-dimensional data extraction unit; a gradation symmetry analysis unit that wraps and superimposes gradation profiles around a point, compares gradation values, and analyzes the symmetry of the gradation profiles; a counter that stores the analysis results of the gradation symmetry analysis unit as a count value; and said CA
A chip component inspection device comprising: a determination unit that determines a mounting position shift of a chip component using data in a data memory.