JPH08228096A - Detecting method for ic position - Google Patents

Abstract

PURPOSE: To make it possible to detect the positions of ICs, including ICs with missing lead terminals, with accuracy, by calculating lead bend for each group of lead terminals on respective side to select a lead terminal with a less bend, and detecting the central position of each group of the lead terminals on respective sides according to the position data on the selected lead terminals. CONSTITUTION: Regression straight lines L1, L2 indicating the correlation between lead terminal numbers and the coordinates of the detected positions of the tips of the lead terminals, are drawn. Lead bends are calculated from the regression straight lines, and regression straight lines L1', L2' are drawn again based on data indicating less lead bends, that is, some data at short distances from the regression straight lines L1, L2. The coordinates for the numbers of the central lead terminals in upper lead terminal groups are calculated from the regression straight lines L1', L2', and the results of the calculations are stored as the coordinates of the central positions of the upper lead terminal groups. Then a microcomputer 6 detects the central position of the group of the lead terminals on each side of IC 100, and calculates the central position and inclination of the IC. It then creates correcting data and outputs it to a position control circuit 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an IC position detecting method for accurately detecting the position of an IC (an integrated circuit including an LSI) supplied to a chip mounter or the like.

[0002]

2. Description of the Related Art For example, an IC for surface mounting is automatically mounted on a printed circuit board by using a chip mounter. At this time, in order to mount the IC accurately at a predetermined position, , The position and orientation of the IC must be controlled accurately.

Therefore, the ICs conventionally supplied to the chip mounter are set one by one on the correction table, the center position and inclination of the ICs are detected, and correction control is performed so that it becomes a prescribed state, and then the pickup is performed. It has been carried out by pinching with and carrying it onto a printed circuit board.

By the way, such an IC for surface mounting is used.
The SOP type in which a large number of lead terminals (pins) are arranged in a row on two side surfaces in the longitudinal direction facing each other of a rectangular parallelepiped package having a low height, and the lead terminals (pins) are respectively arranged on four side surfaces. There are QFP type etc. lined up.

As a method of detecting the set position and inclination of such an IC, a method of detecting the IC by imaging the IC with a TV camera and processing the image data has been conventionally used.

However, since the IC package itself usually has a molding error, the center of gravity of the image data of the lead terminal group on each side is obtained, and the center position and inclination of the IC are detected from the position of each center of gravity. It was

[0007]

However, for example, as shown in FIG. 8A, the four side faces 1 of the package 101 are provided.
01a to 101d, the QFP type IC 100 in which the lead terminals 102 are arranged in rows, or, as shown in FIG.
SOP type I in which lead terminals 102 are provided in line only on 1b
In all of C100 ', not all the lead terminals 102 exist at regular intervals. Especially, in the case of a custom chip, there is a case where the specific lead terminal 102 is intentionally removed. There is no agreement about.

As described above, the center position of the IC in which some of the lead terminals are missing cannot be accurately obtained from the center of gravity of the lead terminal group described above, and the missing lead terminals may be corrected. It is very difficult, and even if it is possible to compensate for the missing lead terminals, there is a problem that logic or programs must be recreated if the missing positions or the number of lead terminals change. Further, when the center of the terminal group is obtained from all the lead terminals, there is a problem that the bending of some of the lead terminals greatly affects the result.

The present invention has been made in view of the above points, and it is an object of the present invention to provide an IC position detecting method capable of accurately detecting the positions of all ICs including ICs in which arbitrary lead terminals are missing. It is an issue.

[0010]

According to the present invention, in order to solve the above-mentioned problems, an image of an IC in which a plurality of lead terminals are arranged at intervals on two opposite side surfaces or four side surfaces of a package. A method of processing data to detect the position of the IC, wherein lead bending is calculated from the data value of each lead terminal position for each lead terminal group on each side surface, and lead terminals with less lead bending are calculated. Select
A configuration is adopted in which the central position of the lead terminal group on each side surface is detected from the position data value of the selected lead terminal.

Further, in the present invention, the lead bending is calculated from the data value at each lead terminal position for each lead terminal group on each side surface, and the lead terminal group is divided into a plurality of areas.
A configuration in which an area with less lead bending is selected from the divided areas, and the central position of the lead terminal group on each side surface is detected from the position data value of the lead terminal in the selected area, and each lead terminal group on each side surface In addition, the lead bending is calculated from the data value at each lead terminal position, the lead terminal group is divided into a plurality of areas, the lead terminals with less lead bending are selected from each divided area, and the selected lead terminals are selected. A configuration is also adopted in which the central position of the lead terminal group on each side surface is detected from the position data value of.

In this case, the lead bend is calculated as a deviation from the regression line obtained from the data value of the lead terminal position. Furthermore, the center position of the IC is detected by calculating the average value of the x-coordinates and the average value of the y-coordinates of the center positions of the lead terminal groups on the respective side surfaces facing each other, which are detected by the above method.
Further, the inclination of the IC is detected by the ratio of the difference between the x-coordinate and the difference between the y-coordinates of the central positions of the lead terminal groups on the side surfaces facing each other, which are detected by the above method.

[0013]

The IC position detecting method according to the present invention is a regression showing a correlation between a series of numbers assigned to all positions where each lead terminal can exist and a coordinate value for the lead terminal group on each side of the package. Obtain a straight line, select a lead terminal with less deviation from the regression line (less lead bending), and select the center number of each lead terminal group (lead terminal does not exist) from the position data value of the selected lead terminal. (It may be the number or the number between the two lead terminals.)
Since the center position of each lead terminal group is detected by obtaining the coordinate value for each of the lead terminal groups, the lead terminal group on each side surface can be used for any IC of any lead terminal pattern or an IC with a marked lead bend. It is possible to accurately detect the central position of the position without being affected by the missing lead terminal and the lead terminal having a significant lead bending.

Further, the coordinate value of the central position of the IC and the inclination can be easily detected from the coordinate value of the central position of the lead terminal group on each side surface facing each other.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be specifically described below with reference to the drawings. FIG. 2 is a schematic configuration diagram of an IC position control system for implementing the IC position detecting method according to the present invention.

This IC position control system has an I set on a correction table 11 of a position control mechanism 15 which will be described later.
C (QFP type IC100 or SOP type IC100 'shown in FIG. 8 may be used, but hereinafter referred to as "IC100")
TV camera 1 that shoots from above and the TV camera 1
An A / D conversion circuit 2 for A / D converting the image signal output from the device, a D / A conversion circuit 3 for converting the image data into an analog image signal again, and a display 4 for displaying the image signal. Correction data creation including an image memory 5 that stores A / D converted image data, and a microcomputer (hereinafter abbreviated as “microcomputer”) 6 that processes the stored image data to create correction data It has a section.

Further, the position control circuit 7 for inputting the correction data and outputting a control signal to the drivers 8, 9, 10 and the motors M1, M2, M3 driven by the drivers 8, 9, 10 respectively. A position correction mechanism 15 including a correction table (rotary table) 11, an X table 12, and a Y table 13 driven by

Then, the X table 12 and the Y table 1
Reference numeral 3 is a so-called X / Y table, which is driven by motors M2 and M3 to make the correction table 11 orthogonal to the X-axis direction and Y-axis.
Moved in the axial direction and set IC100 on it
Adjust the center position of to the reference position. Furthermore, the motor M
The correction table 11 is rotated by 1 to eliminate the inclination of the IC 100.

The microcomputer 6 includes a CPU (central processing unit) for executing various arithmetic processing and a program memory (RO).
M) and a data memory (RAM), etc., the center position of the lead terminal group on each side of the IC 100 is detected by the IC position detecting method according to the present invention, and then the center position and inclination of the IC are calculated to create correction data. Then, it outputs it to the position control circuit 7.

Next, the above-mentioned processing by the microcomputer 6 will be described according to the flowchart of FIG. 1 and also with reference to FIGS. In this example, the position of the QFP type IC is detected and the position is corrected.

When the process shown in FIG. 1 is started, I set in the correction table 11 from the image memory 5 in FIG.
The image data of C100 is input (step S1).

Here, the QFP type IC 100 shown in FIG.
In the figure of the package 101 of FIG.
1b, the left side surface 101c, and the right side surface 101d are arranged in a row, respectively, and the lead terminal groups are referred to as an upper lead terminal group, a lower lead terminal group, a left lead terminal group, and a right lead terminal group, respectively.

Then, first, the coordinate value of the tip end position of each lead terminal of the upper lead terminal group (correctly, the center position of the horizontally bent portion, the position indicated by an X mark in FIG. 3) is detected (step S2). Then, as shown in FIG. 3, in this example, a series of lead terminal numbers (1, 2) are provided from the left end side to each lead terminal 102 and all positions where the lead terminals may actually exist even if they are missing. , 3, ... Are added (step S3).

Thereafter, each lead terminal number and the coordinate value (x coordinate and y coordinate) of the tip position of each lead terminal detected previously.
Regression straight lines L1 and L2 showing the correlation with are created, and lead bending (deviation from the regression line) is calculated from this, and data with little lead bending, that is, partial data with a short distance from the regression lines L1 and L2 ( The regression lines L1 'and L2' are created again from the five circles indicated by circles (shown in FIGS. 4 and 5), and the lead terminal number at the center of the upper lead terminal group (in the example shown, there are 12 lead terminals is 6). The coordinate value (xu, yu) for the middle 6.5 between 7 and 7 is calculated from each regression line L1 ', L2' (step S4), and it is calculated at the center position of the upper lead terminal group (small circle in FIG. 3). (Shown with) are stored as coordinate values.

Note that, in FIG. 3, the central position obtained by averaging the coordinate values of the tip positions of the lead terminals 102 is indicated by a small triangle mark for reference. Similarly, the coordinate values (xd, y
d) (steps S5 to S7), coordinate values (xL, yL) of the center position of the left lead terminal group (steps S8 to S1)
0), the coordinate value of the center position of the right lead terminal group (xr, y
r) (steps S11 to S13) are sequentially calculated and stored.

Then, based on the coordinate value of the central position of each of these lead terminal groups, the coordinate value of the central position of the IC (x
c, yc) is calculated (step S14), and further the angle θ of the IC with respect to the X-axis or the Y-axis is calculated (step S15). The calculation method will be described later.

Thereafter, the correction amount of the IC is calculated (step S16), but the reference coordinate value of the center position of the IC is (xs,
ys) and the standard tilt angle is 0 °, X
The correction amount Δx in the direction, the correction amount Δy in the Y direction, and the tilt correction amount Δθ are obtained by the following calculations.

Δx = xs−xc Δy = ys−yc Δθ = θ The position control circuit 7 of FIG. 2 uses these correction amounts as correction data.
(Step S17), the position control mechanism 15 is driven and controlled, and the position and inclination of the IC 100 are corrected.

By the way, regression lines showing the correlation between each lead terminal number in each lead terminal group and the coordinate value (x coordinate and y coordinate) of its tip position are L1 and L2 in FIGS. 4 and 5, respectively. , L1 ′, L2 ′, it can be created by a known regression analysis method so that the x-coordinate or the y-coordinate for each lead terminal number is evenly scattered on both sides of this straight line.

Therefore, FIG. 6 shows a subroutine of processing for calculating the central position of the upper lead terminal group in the flowchart of FIG. The process of calculating the central positions of the other lead terminal groups is similar to this.

In this flowchart, each symbol has the following meaning.

N (i) ... Lead terminal number x (i) ... x coordinate of tip position of each lead terminal y (i) ... Similarly y coordinate i ... Lead terminal count number Sn ... Integrated value of lead terminal number Sx ... Integrated value of x coordinate of lead terminal tip position Sy ... Similarly, integrated value of y coordinate Sxn ... Integrated value of product of x coordinate and lead terminal number Syn ... Integrated value of product of y coordinate and lead terminal number Sx2 ... Above Integrated value of square of x-coordinate Sy2 ... Integrated value of square of y-coordinate above N ... Number of lead terminals of lead terminal group Nc ... Lead terminal number at center of lead terminal group xu ... x-coordinate of central position of upper lead terminal group yu ... Similarly y coordinate First, in step T1 of FIG. 6, regression lines L1 and L2
Is calculated. This is calculated according to the subroutine (SUB) shown on the right. Each parameter is initialized in steps R1 to R3 of the subroutine, and Sn, Sx, Sy, Sx in steps R4 to R10.
n, Syn, Sx2, and Sy2 are obtained for the lead terminal i, and then the steps R4 to R12 are repeated until all lead terminals are completed by incrementing i in step R11 (step R12). Then, in steps R13 to R20, the gradient bx of a straight line that minimizes the variation in the x coordinate of each lead terminal position.
And the intercept ax and the straight line gradient by and the intercept ay that minimize the variation in the y-coordinate of each lead terminal position. As a result, the regression line L1 shown in FIG. 4 and FIG.
L2 is determined.

Then, in step T2, the distances from the lead terminal positions to the regression lines L1 and L2 are calculated, and sorting is performed (step T3), and a part of the data whose distance from the regression line is short is selected. (Step T
4). In the example of FIGS. 3 to 5, the selected data is the lead terminal numbers 4, 6, 8, 11, and 12. afterwards,
In step T5, a regression line L1 ′ is similarly used for these selected lead terminals by using a subroutine.
And L2 '. Then, in step T6, the x coordinate xu of the central position of the lead terminal group and the y coordinate xy of the central position of the lead terminal group are obtained. This is executed for the lead terminal group on each side surface, and a series of processing is completed.

Next, the IC in the flow chart of FIG.
A method of calculating the coordinate value (xc, yc) of the center position and the tilt angle θ with respect to the X axis or the Y axis will be described.

As shown in FIG. 7, the central positions of the lead terminal groups on the upper, lower, left, and right sides of the IC 100 are set to u, d, L, and r.
And their respective coordinate values (xu, yu), (xd, yd),
When (xL, yL) and (xr, yr) are obtained, the average and y of the respective x coordinates are based on the coordinate values of the central positions u and d or L and r of the lead terminal groups on the two side surfaces facing each other. The coordinate value (xc, yc) of the central position c of the IC 100 is obtained by calculating the average of the coordinates.

That is, xc = (xu + xd) / 2 or (xL + xr) / 2 yc = (yu + yd) / 2 or (yL + yr) / 2. In the case of a QFP type IC, the detection accuracy can be further improved by averaging the coordinates of four points as follows.

Xc = (xu + xd + xL + xr) / 4 yc = (yu + yd + yL + yr) / 4 On the other hand, the inclination angle θ of the IC is the difference between the x-coordinates of the central positions u and d or L and r of the lead terminal groups on the two side surfaces facing each other. And the difference between the y-coordinates are calculated as follows.

Θ = (xu-xd) / (yu-yd) or (xL-xr) / (yL-yr) In the case of a QFP type IC, it is further detected by taking the average of the above two calculation results. The accuracy can be increased.

In the embodiment described above, the lead bend is calculated for each lead terminal group on each side from the data value at each lead terminal position, and the lead lead with the least lead bend is selected and the selected lead is selected. The center position of the lead terminal group on each side is obtained from the terminal position data value.

However, in the manufacture of the IC, many defective portions are generated only in a part of the lead terminals, and in addition, a special array tendency appears, which may result in an unsuitable position data value. For this purpose, a plurality of lead terminal groups (for example, 2
(Division) area, select an area with less lead bending from the divided areas, and detect the center position of the lead terminal group on each side from the position data value of the lead terminals in the selected area. Is also possible. In this case, it is possible to eliminate an area where the lead bend is large, and thus it is possible to perform more accurate detection.

On the other hand, on the contrary, the lead terminal group is divided into a plurality of areas, the lead terminals with less lead bending are selected from each of the divided areas, and each side surface is selected from the position data value of the selected lead terminal. It is also possible to detect the central position of the lead terminal group. In this case, the lead terminals in the area where the lead bends a lot are selected, and the center position of the lead terminal group is obtained, so that it is possible to perform detection while eliminating the non-uniform arrangement of the lead terminals.

In the example described above, the lead bend is calculated as a deviation from the regression line obtained from the data value of the lead terminal position, but the following method can be considered as a method of obtaining another lead bend. One of them is a method of comparing each distance between adjacent leads and a predetermined set value of the lead interval or an average value or a median value of the distance between the leads. In addition, a relative distance between a statistically determined virtual origin (for example, an average value of each lead position is used as the origin) and each lead position is calculated based on a preset lead interval setting value and the lead actual information. You can From this, it is also possible to detect the lead bending by comparing the relative distance between the ideal virtual origin and each ideal lead position.

[0043]

As described above, according to the present invention, the positions of all ICs including the IC in which any lead terminal is missing, that is, the center position of the lead terminal group on each side surface, the center position of the IC. , The tilt angle and the like can be accurately detected.

[Brief description of drawings]

FIG. 1 is a flowchart of processing according to the present invention by a microcomputer 6 of FIG.

FIG. 2 I for implementing the IC position detection method according to the invention
It is a schematic block diagram of a C position control system.

FIG. 3 is an explanatory diagram in a case where a central position of an upper side lead terminal group is obtained by the IC position detecting method of the present invention.

[Fig. 4] Lead terminal number and x of the tip position of each lead terminal
It is explanatory drawing of the method of calculating | requiring the x coordinate of the center position of a lead terminal group from the regression line which shows correlation with a coordinate.

FIG. 5: Lead terminal number and y at the tip position of each lead terminal
It is explanatory drawing of the method of calculating | requiring the y coordinate of the center position of a lead terminal group from the regression line which shows correlation with a coordinate.

FIG. 6 is a flowchart showing a subroutine of processing for calculating the central position of the upper lead terminal group in the flowchart of FIG.

7 is an explanatory diagram of a method of calculating a coordinate value (xc, yc) of the center position of the IC and an inclination angle θ with respect to the X axis or the Y axis in the flowchart of FIG. 1.

FIG. 8 is a schematic plan view showing an example of a QFP type IC and a SOP type IC.

[Explanation of symbols]

 1 TV camera 2 A / D conversion circuit 3 D / A conversion circuit 4 Display 5 Image memory 6 Microcomputer (microcomputer) 7 Position control circuit 8, 9, 10 Driver 11 Correction table 12 X table 13 Y table 100, 100 ' IC 101 Package 102 Lead terminal

Claims (6)

[Claims] 1. The package has two opposite sides or four.
A method of processing image data of an IC in which a plurality of lead terminals are arranged in a row on each side surface and detecting the position of the IC, wherein each lead is provided for each lead terminal group on each side surface. It is characterized in that the lead bending is calculated from the data value of the terminal position, the lead terminal with less lead bending is selected, and the central position of the lead terminal group on each side is detected from the position data value of the selected lead terminal. IC position detection method. 2. Two opposite sides or four of the package.
A method of processing image data of an IC in which a plurality of lead terminals are arranged in a row on each side surface and detecting the position of the IC, wherein each lead is provided for each lead terminal group on each side surface. The lead bending is calculated from the data value of the terminal position, the lead terminal group is divided into a plurality of areas, the area with less lead bending is selected from the divided areas, and the position data value of the lead terminal of the selected area To detect the center position of the lead terminal group on each of the side surfaces. 3. Two opposite sides or four of the package.
A method of processing image data of an IC in which a plurality of lead terminals are arranged in a row on each side surface and detecting the position of the IC, wherein each lead is provided for each lead terminal group on each side surface. The lead bending is calculated from the data value of the terminal position, the lead terminal group is divided into a plurality of areas, the lead terminal with less lead bending is selected from each divided area, and the position data value of the selected lead terminal is selected. To detect the center position of the lead terminal group on each of the side surfaces. 4. The lead bending is calculated as a deviation from a regression line obtained from a data value of a lead terminal position, and the lead bending is calculated.
Item 7. The IC position detection method according to item. 5. The center position of the IC is detected by calculating an average value of x-coordinates and an average value of y-coordinates of the detected central positions of the lead terminal groups on the respective side surfaces facing each other. The IC position detecting method according to any one of 1 to 4. 6. The inclination of the IC is detected by the ratio of the difference between the x-coordinate and the difference between the y-coordinates of the detected central positions of the lead terminal groups on the respective side surfaces facing each other. The IC position detection method according to any one of items 1 to 7.