JP2000124697A - Electrode height inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability of ball height inspection by deciding that the height of an electrode is abnormal, when the distance from the electrode of electronic components to a regression plane is equal to or more than a preset reference value. SOLUTION: A component-retaining device samples the height data of the entire bottom surface of electronic component by a three-dimensional image pickup device. In image processing, information on the diameter of a ball is used and a template for expressing a ball shape is created. Then, the template is compared with an image which is being picked up, the center coordinates of each ball are obtained, the height of the ball at each ball center is measured from a three-dimensional image, and a regression plane is calculated. Height from a regression plane 20 is examined, in comparison with lower-limit and upper-limit values f1 and f2 in the tolerance of height from the regression plane 20 which is given in advance for all balls, thus improving inspection reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for picking up an electronic component by a suction nozzle, picking up the electronic component and processing the image to identify the position where the electronic component is sucked and to inspect the electronic component. The present invention also relates to a component mounting apparatus that mounts the electronic component at a predetermined position on a circuit board while correcting a positional shift of suction only for a component having no abnormality.

[0002]

2. Description of the Related Art A BGA (Ball Grid Array) CSP in which electrodes are two-dimensionally arranged as shown in FIG.
(Chip Size Package; including fine pitch BGA and micro BGA) is a QFP (Qua).
Since the number of terminals per unit area can be increased as compared with d Flat Package, it has been actively used in a mounting field requiring high-density mounting and reduction in size and weight. BGA / CSP
Has dozens to hundreds of balls, but due to manufacturing defects or the like, the balls are rarely mounted in a state of being lost. Therefore, the ball inspection is performed at the same time as the component recognition of the component mounting apparatus to prevent the mounting of the defective component. The main method of ball inspection is an optical inspection method that irradiates the ball with light and inspects the ball according to the magnitude of the reflected light. In many cases, only missing balls could be detected. Therefore, recently, in order to enhance the ball detection ability, a technique disclosed in Japanese Patent Application No.
There is a tendency to inspect the height of a ball using a two-dimensional imaging device.

A conventional BGA / CSP ball height inspection technique will be described with reference to FIGS. Conventional B
The GA / CSP ball height inspection method uses the technique of the QFP lead floating inspection shown in FIG. This means that when the component is placed on a flat surface as shown in FIG. 10 (a), some leads are grounded.
, There are at least three parts, for example, 201, 20
A triangle 204 composed of at least one set of three grounding points grounded at 2,203 has a center of gravity 205 of the component inside.
including. The ground plane including the triangle at this time is called a seating plane (206 in FIG. 10C). The QFP lead floating inspection is to inspect how far the height of each lead at the tip of the lead is from the seating plane 206 as shown in FIG. 10 (c). In the above case, it is determined that the component inspection is abnormal with respect to the lead floating.

Similarly, in the conventional BGA / CSP ball height inspection, as shown in FIGS. 11 (a), 11 (b) and 11 (c), the height of each ball at the tip of the ball is determined and the part is flattened. Ground at least 3 points when placed on a surface, ground 3
The triangle composed of points includes the center of gravity of the component inside. If the distance from the ground plane, that is, the seating plane, to the height of each ball at this time is equal to or greater than a predetermined height inspection allowable value, it is determined that there is a component inspection abnormality with respect to the ball height floating.

[0005]

In a BGA / CSP, when a component manufacturer performs a component test, a metal piece is applied to perform an electrical inspection, so that a dent remains on the ball. If there is a dent on the ball, the height data of the ball tends to include an error. In the related art, as shown in FIG. 12, when the ball 210 forming the seating plane has a dent and the height is likely to include an error, the inclination of the seating plane with respect to the component is likely to change (211 and 212). There is a case where the floating amount of the tip of the ball 213 around the component from the seating plane becomes large and it is determined that a normal ball is abnormal. Specifically, since the floating amount is 150 microns and the testable range is 100 microns, the test may not be possible. In particular, as shown in FIG. 13A, a point 220 constituting the seating plane includes a height error and is near the component center of gravity 221 or, as shown in FIG. When the two points 222 and 223 include a height error, and the straight line connecting the two points passes near the component center of gravity 224, the tip of the ball included in the region 230 or the region 231 or the like easily separates from the seating plane. It is easy to determine a normal ball as NG.

Therefore, in the prior art, there is a problem in the reliability of the ball height inspection. The present invention has been made to solve such a problem, and has as its object to provide a highly reliable ball height inspection method.

[0007]

SUMMARY OF THE INVENTION A method of the present invention is a method for inspecting the height of an electrode of an electronic component in which electrodes are two-dimensionally arranged, wherein the electronic component is imaged by a three-dimensional image pickup device. A first step, a second step of obtaining the positions (X, Y) of all the electrodes of the electronic component in a two-dimensional plane, and a distance from a reference plane of the three-dimensional image pickup device to the electrodes of the electronic component Is calculated as the height (Z) of the electrode, and the square value of the distance from the electrode of the electronic component to a certain plane is calculated.
A plane where the sum of the power values is the minimum value (hereinafter referred to as a regression plane)
And a fifth step of determining that the height of the electrode is abnormal if the distance from the electrode of the electronic component to the regression plane is equal to or greater than a predetermined reference value. It is characterized by the following.

A second method is a method for inspecting the height of an electrode of an electronic component in which electrodes are arranged two-dimensionally,
A first method of imaging the electronic component by a three-dimensional image capturing device;
A second step of determining the positions (X, Y) of all the electrodes of the electronic component in a two-dimensional plane, and a distance from a reference plane of the three-dimensional image pickup device to the electrodes of the electronic component. A third step of obtaining the height (Z1) of the electrode;
A fourth step of calculating the height (Z2) of the electrode peripheral part in the same manner as the step, a fifth step of calculating a height difference (Z1-Z2) between the electrode and the electrode peripheral part, and a step of calculating the height difference of all the electrodes. A sixth step of determining that the height of the electrode is abnormal if the absolute value is equal to or greater than a predetermined reference value.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A ball height inspection method according to one embodiment of the present invention will be described below with reference to the drawings.

In the present embodiment, a ball corresponds to an example that fulfills the function of the “electrode” described in the above “Means for Solving the Problems”.

(Embodiment 1) FIG. 1 is a flowchart of the present invention.

In FIG. 5, reference numeral 31 denotes a component mounting apparatus. The following control regarding the operation of the component mounting apparatus 31 is performed by the control device 18. The component holding device 1 is mounted on the XY robot 7, and is used to hold the component and to mount the held component at the mounting position of the circuit board 15.
The robot 7 can move in the X and Y directions orthogonal to each other, in the embodiment, in the horizontal direction. The component holding device 1 includes a suction nozzle 9. The rotation control device 17 can rotate the suction nozzle 9 by rotating around its axis, rotate the electronic component at a predetermined angle, and correct a slight rotational deviation during suction. The control device 18 of the component mounting apparatus 31 stores and manages which electronic component is to be mounted on which position on the circuit board 15 from which supply unit, and controls the overall operation of the component mounting apparatus. The image pickup device 3 is a three-dimensional image pickup device having a structure shown in FIG. 6 and FIG. 7 viewed from a direction perpendicular to FIG. Then, the height information of each Y direction can be obtained by picking up the height information of the imaging object irradiated with the laser beam by the laser light receiving units 117a and 117b in time series. Furthermore, by imaging the object while moving in the X direction, it is possible to obtain height data at coordinates X and Y, that is, a three-dimensional image of the object. The visual recognition device 13 specifies the position of the component in a two-dimensional, that is, horizontal direction, from the three-dimensional data of the electronic component sent from the three-dimensional imaging device. Perform an inspection. In this embodiment, the three-dimensional imaging device 3 is a device using laser light and a polygon mirror. However, a slitting light is obliquely applied to the three-dimensional imaging device 3 to specify the height of the component surface from the position where the light is reflected. May be used as an imaging device.

The component holding device 1 moves to a predetermined component supply unit 8, sucks the electronic component 10 by lowering the suction nozzle 9, raises the suction nozzle 9, and sets the mounting angle of the electronic component by the rotation control mechanism 17. Rotate according to. next,
The component holding device 1 moves close to the three-dimensional imaging device 3,
The height data of the entire bottom surface of the electronic component 10 is collected by the three-dimensional imaging device 3 while moving at a constant speed in the X direction orthogonal to the scanning direction of the laser. Here, the height data is defined to be larger as it is closer to the imaging device, that is, farther from the tip of the suction nozzle.

The data relating to the parts is stored in the control unit 18 and holds the dimensions of the parts, the diameter of the balls, the pitch of the balls, the number of balls on each side of the periphery of the parts, the total number of balls, and the like.

In the image processing, first, as shown in FIG.
A template representing the ball shape is created using the information on the ball diameter. Next, when the template FIG. 8A is compared with the captured image FIG. 8B, a high degree of coincidence is obtained at the center of the ball, and the center coordinates (Xi, Yi) of each ball are obtained. be able to. Next, the height Zi of the ball at each ball center (Xi, Yi) is measured from the three-dimensional image. Next, a regression plane for Z is calculated by the following method.

The regression plane for the total number N of balls is defined as follows: When the plane equation is z (x, y) =-ax-by-c, the coordinates (Xi, Yi, Zi) (i = 1
To N), the deviation of Z from the point on the plane lowered in the Z direction is determined, the square value of the deviation is added for each ball, and a, b, and c that minimize the sum thereof are determined. That is, the deviation of Z: Zi−z (Xi, Yi) = a · Xi + b · Yi + Zi + c Sum of squares of the deviation E: E = Σ (ax + by + z + c) ² → minimum (where Xi, Yi, Zi in parentheses of は are , X, y, z. The same applies hereafter.) This is based on the partial distribution method, where ∂E / ∂a = 0 and ∂E / ∂b =
0, ∂E / ∂c = 0 can be solved.

∂E / ∂a = aΣx ² + bΣx ² + cΣx + Σxz = 0 ∂E / ∂b = aΣxy + bΣy ² + cΣy + Σyz = 0 ∂E / ∂c = aΣx + bΣy + cN + Σxz = 0 D = (Σx ² ) * (Σy ² ) * N + 2 * (Σxy) * (Σ
x) * (Σy) −N * (Σxy) ² − (Σx) ² * (Σy
² ) − (Σy) ² * (Σx ² ) a = − ((N * (Σy ² ) − (Σy) ² ) * (Σxz) +
((Σx) * (Σy) −N * (Σxy)) * (Σyz)
+ ((Σxy) * (Σy) − (Σx) * (Σy ² )) *
(Σz)) / D b = − (((Σx) * (Σy) -N * (Σxy)) *
(Σxz) + (N * (Σxx)-(Σx) ² ) * (Σy
z) + ((Σx) * (Σxy) − (Σy) * (Σ
x ² )) * (Σz)) / D c = − (((Σxy) * (Σy) − (Σx) * (Σ
y ² )) * (Σxz) + ((Σx) * (Σxy) − (Σ
x ² ) * (Σy)) * (Σyz) + ((Σx ² ) * (Σy
² ) − (Σxy) ² ) * (Σz)) / D, the equation ax + by + z + c of the regression plane is obtained.
= 0 is obtained.

Now, at the end of the ball height inspection, a ball floating measurement is performed. All balls (Xi, Yi, Zi)
As for (i = 1 to N), as shown in FIG. 2, the height from the regression plane 20 is compared with the lower limit value f1 and the upper limit value f2 of the allowable range of the height from the regression plane 20, Zi-
Z (Xi, Yi), that is, a · Xi + b · Yi + Zi
Test + c.

F1 <a.Xi + b.Yi + Zi + c <f
In 2, the height of the ball 21 is normal. If it is out of the range, the height of the ball 21 is determined to be abnormal, and the component is defective. If it is necessary to determine only the lack of the ball, it is not necessary to compare with the allowable value when the ball height is too high, f2.

In the above description, the next processing is performed after the processing is completed for all the balls. However, the processing may be sequentially performed for each ball, and the processing may be repeated for each ball.

When the two-dimensional positioning is performed as described above, and the component inspection result is normal by the above-described method, the circuit board 15 is moved above the mounting position while correcting the two-dimensional positioning amount. On the other hand, the rotation control mechanism 17 corrects a tilt shift of the electronic component. The component holding device 1 mounts the electronic component 10 on the circuit board 15 by lowering the suction nozzle 9.

(Embodiment 2) FIG. 3 is a flowchart corresponding to Embodiment 2 of the present invention.

As compared with the first embodiment, the operation of the component mounting apparatus is the same, but only a part of the ball inspection method is different.

In the image processing, first, as shown in FIG. 8, a template representing the ball shape is created using the information on the diameter of the ball. Next, the ball is extracted by comparing the template with the image, and the center coordinates (Xi, Yi) of each ball are extracted.
Ask for. Next, the height Zi of the ball at each ball center (Xi, Yi) is measured. The operation up to this point is the same as in the first embodiment.

Next, as shown in FIG. 4, the height Wi around the ball 21 is measured. Next, the height Zi of the ball 21 and
The difference between the height Wi around the ball 21 and Zi-Wi is determined.

Finally, the height of the ball 21 is inspected using the lower and upper limits of the height of the ball 21 and g1 and g2 which are set in advance (FIG. 4). When g1 <Zi−Wi <g2, the height of the ball is normal. In addition, if only the missing ball determination is necessary, the allowable value when the ball height is too high, g
No comparison with 2 is required.

In the above description, the next processing is performed after the processing is completed for all the balls. However, the processing may be sequentially performed for each ball, and the processing may be repeated for each ball.

[0028]

According to the present invention, a component mounting apparatus with high inspection reliability can be provided.

[Brief description of the drawings]

FIG. 1 is an operation flowchart of the present invention.

FIG. 2 is an explanatory diagram of the inspection method of the present invention.

FIG. 3 is an operation flowchart of another embodiment of the present invention.

FIG. 4 is an explanatory diagram of an inspection method according to another embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of the present invention.

FIG. 6 is an explanatory diagram of an imaging device constituting the present invention.

FIG. 7 is an explanatory diagram of an imaging device constituting the present invention.

FIG. 8 is an explanatory diagram of a method for obtaining a center of an electrode.

FIG. 9 is an explanatory view of a part.

FIG. 10 is an explanatory diagram of a conventional technique.

FIG. 11 is an explanatory diagram of a conventional technique.

FIG. 12 is an explanatory diagram of a problem in the conventional technique.

FIG. 13 is an explanatory diagram of a problem in the conventional technique.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 component holding device 3 three-dimensional imaging device 7 XY robot 8 component supply unit 9 suction nozzle 10 electronic component 13 visual recognition device 15 circuit board 17 rotation control mechanism 18 control device 20 return plane 21 ball 22 ball tip 31 component mounting device 110 laser Light emitting device 112 Polygon mirror 117a Laser light receiving device 117b Laser light receiving device 201-203 Lead grounded to plane 204 Triangle formed of three grounded parts 205 Center of gravity of part 206 Seating plane 210 Ball constituting seating plane 211, 212 Seating plane 213 End ball 220 Ball constituting a seating plane 221 Component center of gravity 222 Ball constituting a seating plane 223 Ball constituting a seating plane 224 Goods center of gravity 230, 231 balls height anomaly is prone area

Claims (2)

[Claims] 1. A method for inspecting the height of an electrode of an electronic component in which electrodes are arranged two-dimensionally, wherein a first step of imaging the electronic component by a three-dimensional image capturing device, and all of the electronic components A second step of obtaining the position (X, Y) of the electrode in the two-dimensional plane, and determining the distance from the reference plane of the three-dimensional image pickup device to the electrode of the electronic component by the height (Z) of the electrode.
And a regression plane that calculates a square value of a distance from an electrode of the electronic component to a certain plane and calculates a minimum value of the sum of the square values for all the electrodes of the electronic component. And a fifth step of determining that the height of the electrode is abnormal if the distance from the electrode of the electronic component to the regression plane is equal to or greater than a predetermined reference value. An electrode height inspection method, characterized in that: 2. A method for inspecting the height of an electrode of an electronic component in which electrodes are arranged two-dimensionally, wherein a first step of imaging the electronic component by a three-dimensional image pickup device, and all of the electronic components A second step of determining the position (X, Y) of the electrode in the two-dimensional plane, and the distance from the reference plane of the three-dimensional image pickup device to the electrode of the electronic component is determined by the height (Z) of the electrode.
A third step for obtaining the height (Z2) of the electrode peripheral part in the same manner as the third step; and a fifth step for calculating the height difference (Z1-Z2) between the electrode and the electrode peripheral part. An electrode height inspection method, comprising: a step; and, if the absolute value of the height difference exceeds a predetermined reference value, determining that the electrode height is abnormal.