JP2003106824A - Shape-measuring method and apparatus, control program, and record medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shape measuring method or the like for enabling the measurement of the amount of displacement in a micron order to a measuring target such as an electric circuit component that is mounted on a printed circuit board. SOLUTION: In the shape-measuring method, auto-focusing is successively executed at each measuring point in the measuring target using a noncontact three-dimensional measuring apparatus, and height is measured at a focus position in a focused state. The shape-measuring method comprises a first process for judging a focused state by executing auto-focusing by the final measuring magnification for measuring accuracy that is finally required at the measuring point of the measuring target, and a second process for detecting a focus position in a focused state by executing auto-focusing by reference measured data obtained by measuring the measuring target by magnification that is lower than the final measuring magnification.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shape measuring method for measuring the shape of an electric circuit component or the like using a non-contact three-dimensional measuring device.

[0002]

2. Description of the Related Art In recent years, electric circuit parts such as electric parts mounted on a printed circuit board for electric circuits have been integrated into high density and miniaturized along with speeding up of electric signals, resulting in miniaturization of signal wiring and increase in pin count. Is becoming noticeable. Along with this, the electric circuit components on the printed circuit board are deformed by heat or physical stress, and the reliability test for testing the connection life thereof is becoming more important. In this test, accurately grasping the amount of deformation of the electric circuit component on the printed circuit board is indispensable for predicting the connection life.

As an example of a conventional flip chip bonding inspection method on a printed circuit board, for example, Japanese Patent Laid-Open No. 11-183.
As described in Japanese Patent No. 406, there is known a method of performing height measurement by an X-ray image or a laser focus displacement meter. This method does not perform a series of measurements from the board to the electric circuit parts, but individually measures the height of the flip chip top surface and the joint board surface and averages the measurement points to determine the height. Is calculated.

[0004]

However, in the above conventional technique, the measurement point is not specified, and the height (deformation amount) between the flip chip and the substrate cannot be measured in the order of microns.

Further, since the focus range is narrowed at the time of measurement at high magnification, the focus due to autofocus cannot be achieved at a large step, and the measurement is interrupted, which is a fundamental problem that measurement is impossible.

In view of the above-mentioned conventional problems, the present invention provides a shape measuring method and the like capable of measuring a displacement amount of a micron order with respect to a measuring object such as an electric circuit component mounted on a printed circuit board. The purpose is to do.

[0007]

In order to achieve the above object, according to the shape measuring method of the present invention, the shape of an object to be measured is measured at a predetermined measurement magnification using a non-contact three-dimensional measuring device. In the shape measuring method, the reference measurement data obtained by measuring the measurement object at a magnification lower than the predetermined measurement magnification is prepared, and the reference measurement data is used to refer to the predetermined measurement magnification. The feature is that measurement is performed.

According to the shape measuring method of the present invention, by using the non-contact three-dimensional measuring device, auto-focusing is sequentially performed at each measurement point of the object to be measured, and the focus position is brought into a focused state. In the shape measuring method for measuring the height of the, the first to determine the in-focus state by executing autofocus at the final measurement magnification for measuring the finally required accuracy at the measurement point of the measurement object. When the out-of-focus state occurs in the stroke and the first stroke, autofocus is performed using the reference measurement data obtained by measuring the measurement object at a magnification lower than the final measurement magnification. And a second step of detecting a focus position in a focused state.

According to the shape measuring apparatus of the present invention, in the shape measuring apparatus for measuring the shape of the measuring object at a predetermined measuring magnification, the measuring object is measured at a magnification lower than the predetermined measuring magnification. It is characterized in that it is provided with means for performing measurement at the predetermined measurement magnification while referring to the obtained reference measurement data.

According to the shape measuring apparatus of the present invention, the shape measuring apparatus performs the autofocus sequentially at each measurement point of the object to be measured to measure the height at the focus position where the object is in focus. In, the first means for determining the in-focus state by performing autofocus at the final measurement magnification for measuring the finally required accuracy at the measurement point of the measurement object, and the first means In the out-of-focus state, autofocus is performed using the reference measurement data obtained by measuring the measurement object at a magnification lower than the final measurement magnification, and the focus becomes the in-focus state. And a second means for detecting the position.

According to the control program of the present invention,
A control program for executing a shape measuring method for measuring a shape of an object to be measured at a predetermined measurement magnification using a non-contact three-dimensional measuring device, wherein the measurement target is a magnification lower than the predetermined measurement magnification. It is characterized by including a step of measuring an object to create reference measurement data, and a step of performing measurement at the predetermined measurement magnification while referring to the reference measurement data.

According to the control program of the present invention,
A non-contact three-dimensional measuring device is used to sequentially perform autofocus at each measurement point of the measuring object, and to perform a shape measuring method for measuring height at a focus position where a focused state is achieved. A control program, a first step of determining an in-focus state by executing autofocus at a final measurement magnification for measuring an accuracy finally required at a measurement point of the measurement object; When the out-of-focus state is obtained in one step, autofocus is performed using the reference measurement data obtained by measuring the measurement object at a magnification lower than the final measurement magnification, and the focus is adjusted. And a second step of detecting the focus position in the state.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a partial schematic side view showing an IC package component mounted on a printed circuit board as an example of a measuring object for executing the shape measuring method according to the embodiment of the present invention. FIG. 2 is a schematic plan view of the CSP package shown in FIG.

FR4 IC mounted on printed circuit board 1
The package is a CSP package, and the shape thereof is a square having a length and width of about 16 mm square, the thickness of the mold 2 is about 0.9 mm, and the thickness of the solder ball 3 provided under the mold is about 0. It is 0.4 mm.

The outer shape (cross-sectional shape) of the CSP package including the printed circuit board 1 is measured at a measurement magnification of 100 times the objective lens.

First, in order to accurately compare the deformation amounts on the order of microns, in order to measure the same position as much as possible, two points are determined as measurement alignment points (alignment points). To determine both positions, observation and determination are performed at the same magnification as the measurement magnification (visual alignment magnification on the monitor: about 3800 times). In this embodiment, since the upper surface of the CSP package is used as a reference surface to compare the deformed shapes, the CS
Alignment will be performed at both ends (5 and 6 in the figure) of the P package.

As shown in FIG. 2, φ0.5 mm to φ for mounting positioning at the four corners on the diagonal of the CSP package.
There is a circle mark 4 of 1.5 mm, and inside the circle mark 4,
Remarkably smooth compared to the mold surface. When the mold surface shape is observed on a monitor at a magnification of about 3800, it is impossible to determine or recognize a measurement specific point because the unevenness is severe. Since the present embodiment has high measurement accuracy, it is easy and appropriate to use the inside of the circle mark 4 to specify a specific minute point of 1 μm or less. Therefore, the measurement alignment point is set within the range of the circle mark 4. .

In the present embodiment, φ is set within the range of the circle mark 4.
Two measurement alignment points of 0.6 to 0.7 μm or less are set (5 and 6 in FIG. 2). At this time, since the alignment points 5 and 6 have many similar points, it is easy to confirm the same point by photographing the peripheral shape pattern.

Next, a method of measuring the shape of the CSP package mounted on the printed board 1 will be described with reference to the flowchart of FIG.

Here, the measurement conditions of this example are as follows.

The non-contact three-dimensional measuring device 10 shown in FIG. 1 is used, and the objective lens is 10 times, 50 times, or 100 times. The laser used is a He-Ne laser with a wavelength of 6
33 nm, output 1.8 mW class IIIa.
The measurement light is scattered light of 1.5 mW or less, and the measurement pitch is 1 μm, and the measurement proceeds in the diagonal direction of the CSP package (direction W in the figure).

First, the measurement sample is observed at a measurement magnification for finally measuring the required accuracy, and a recognizable specific point (11 in FIG. 1) is determined as the measurement starting point (step S11). In this embodiment, since the objective lens 100 times is the final measurement magnification, the monitor is observed at that magnification,
The specific point 11 that is the measurement start point is determined.

Subsequently, reference measurement data is created (step S12). In this process, first, the above 100
The double objective lens is changed to an objective lens for reference measurement data measurement. That is, the objective lens having the highest magnification has a depth of field capable of auto-focusing (following) in all height regions for shape changes from the start of measurement to the end of measurement. This objective lens magnification is lower than the final measurement magnification, and the magnification depends on the maximum height difference of the measurement sample. However, in order to improve the measurement accuracy, the highest possible magnification is desirable. In this embodiment, it is assumed that the measurement is performed using a 10 × objective lens for measuring the reference measurement data.

In the measurement of the reference measurement data, first, the measurement start point 11 determined by observing with the 100 × objective lens is observed with the 10 × objective lens and aligned. Since the magnification is low, the light of the laser spot is adjusted to the vicinity including the measurement point.
The combined point is designated as the measurement start point, and measurement is started at the same pitch and measurement length as the 100 × objective lens measurement conditions. After the measurement at the measurement end point 12, the measurement data with this 10 × objective lens is set as (xn, yn, zn) and used as reference measurement data.

Next, using a 100 × objective lens with a final measurement magnification, the measurement is started after alignment with the measurement start point (step S13). At a certain measurement point coordinate (xn, yn) with the 100 × objective lens (step S14), when autofocus is applied to bring the object into focus (focus in) (step S15), the measurement height Zn and move the stage to the next measurement point (step S
16). If all the measurement points can be focused, the measurement is similarly ended (step S17).

However, when the focus is not achieved and auto-focusing is impossible (focus-out), the reference measurement data of low magnification is used (step S18).

First, at the first time, the measurement height data (zn) of the reference measurement data coordinate (xn, yn) which is the same as the coordinate (xn, yn) which is out of focus at 100 times is referred to, and the focus position is set at that height. To move. After moving the focus position, auto focus is again applied to determine whether focus is possible (step S15). If in focus and focus is possible, move to the next measurement point (step S1)
6).

However, autofocus may not be possible even at this position. The cause is that the focus range at 10 times is wider than the focus range at 100 times, so it is accurate whether the data is matched with the lower or higher 10 times before and after the step even at the same coordinate. I can't decide to. That is, the reference measurement data height is 100
This is because there is a case where the measurement height is doubled.

Then, next, reference is made to the measuring points before and after. Two
The second time is the measurement height data (zn + 1) of (xn + 1, yn + 1), which is the measurement point next to xn in the reference measurement data coordinates.
And move the focus position to that height. Figure 4
As shown in, by measuring the same sample,
It is more likely that the focus position will be aligned by referring to the next point that could not be focused as the shape change flow. Here, 18 white circles in the figure represent 100 times measurement points, and 1
The black circle 7 indicates the measurement point at 10 times.

After moving the focus position, auto focus is again applied to determine whether focus is possible (step S15). If the object is in focus and can be focused, it moves to the next measurement point (step S16).

However, if auto-focusing is not possible even at this coordinate, the previous measurement point (xn-1, y
The focus position is moved to the height by referring to the measured height data (zn-1) of n-1). This case corresponds to the case shown in FIG.

Thereafter, the coordinates (xn + 2, yn + 2) are similarly obtained.
Height (zn + 2), (xn-2, yn-2) height (zn-2), and repeat N times until a position where auto focus is possible can be detected. The N number is adjusted according to the difference in the characteristics of each lens such as the sample shape and the measurement pitch (difference in focus range).

By repeating this, height measurement is performed at the focus-in position, all points including the measurement end point 12 are measured, and then the measurement ends.

In this way, even when the objective lens with 100 times the final measurement magnification is used to bring the focus out, auto focus becomes possible by moving the focus position according to the reference measurement data as shown in step S18. It is possible to continue. Further, even if the height becomes low, by performing the processing of step 18,
It becomes possible to measure.

However, if autofocus is not applied even after repeating the above N times, that is, if the focus is out at the (N + 1) th time, it is judged that this measurement condition is not possible and the measurement is stopped (step S19). One of the causes of the lack of focus is that the position (height) focused at 10 times is not within the focus range of 100 times. This is due to the difference in lens measurement accuracy.

Therefore, the measurement magnification is first lowered (step S20). That is, before the measurement at 100 times, the objective lens is changed to a lens between 10 times and 100 times, that is, a 50 times objective lens having a measurement magnification close to 10 times of the reference measurement data. The magnification may be changed not by the objective lens but by adjusting the optical system in the middle.

Next, measurement is performed at 50 times while using the measurement data at 10 times as reference measurement data. The measurement data at 100 times is performed again by using the measurement data at 50 times as new reference measurement data.

In this embodiment, the step between the printed circuit board and the upper surface of the CSP package is about 1 mm, and the step is within the autofocusable range by the measurement with the 10 × objective lens. As described above, high magnification measurement becomes possible by measuring at a lower magnification and performing step-up measurement. That is, even when the change in shape of the measurement sample is large, or even if the measurement is performed with a high-magnification lens with a shallow depth of field, the step-up measurement is performed by dividing the magnification as in steps S20 and S21. By doing so, it becomes possible.

By the above measuring method, as shown in the graph of FIG. 6, the shape of the CSP package mounted on the printed circuit board having a step of about 1 mm can be measured in the order of micron. That is, in the present embodiment, detailed measurement is performed based on the rough measurement result, and a minute specific point is used as a measurement alignment point, and a series of measurement is performed from the substrate to the electric circuit component. The amount of displacement can be measured.

Although CSP and BGA are used also in the electric circuit parts in the present embodiment, the same can be applied to QFP, chip resistors, chip capacitors and the like. In addition, it is naturally possible to use it for objects other than electric circuit parts that require measurement on the order of microns.

The above-described measuring method can be automated by programming the procedure shown in the flow chart of FIG. 3 and storing it in a storage device in the measuring device to operate. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. As the storage medium for supplying the program code, for example, a floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, magnetic tape, non-volatile memory card, or ROM is used. You can In addition, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also the OS or the like running on the computer executes actual processing based on the instruction of the program code. It goes without saying that a case where some or all is performed and the functions of the above-described embodiments are realized by the processing is also included.

Further, after the program code read from the storage medium is written in the memory provided in the function expansion board inserted into the computer or the function expansion unit connected to the computer, based on the instruction of the next program code. Needless to say, this also includes the case where the CPU or the like provided in the expansion board or the expansion unit performs the expansion function to perform a part or all of the actual processing, and the processing realizes the function of the above-described embodiment. Yes.

[0044]

As described above in detail, according to the present invention, it is possible to measure the displacement amount of the order of micron with respect to the measuring object. That is, it can be used as an object to be measured in electric circuit parts and printed circuit boards used in many electric devices, and by measuring the shape of each accurately and grasping the deformation state accurately, the solder bump It is possible to minimize the stress applied to the electric circuit parts such as the above, improve the connection reliability, and extend the connection life.

[Brief description of drawings]

FIG. 1 is a partial schematic side view showing an IC package component mounted on a printed circuit board according to an embodiment of the present invention.

FIG. 2 is a schematic plan view of the CSP package shown in FIG.

FIG. 3 is a flowchart showing a shape measuring method according to an embodiment.

FIG. 4 is a diagram schematically showing the relationship between the shape of a CSP package and a measurement position of 100 times and a measurement position of 10 times.

FIG. 5 is a diagram schematically showing a relationship between a 100 times measurement position and a 10 times measurement position when a measurement surface has a complicated shape.

FIG. 6 is a graph showing shape measurement values of a CSP package on a printed circuit board.

[Explanation of symbols]

1 on printed circuit board 2 mold 3 solder balls 4,5 alignment points

Continued front page    F-term (reference) 2F065 AA01 AA02 AA04 AA06 AA20                       AA24 AA25 AA53 AA65 BB01                       BB05 BB27 CC01 CC28 DD03                       DD10 FF10 FF26 FF41 FF67                       GG05 GG22 JJ03 JJ26 LL04                       PP12                 5F044 KK01 LL01

Claims (16)

[Claims] 1. A shape measuring method for measuring a shape of an object to be measured at a predetermined measurement magnification using a non-contact three-dimensional measuring device, wherein the object to be measured is measured at a magnification lower than the predetermined measurement magnification. A shape measuring method, characterized in that reference measurement data obtained as described above is prepared, and measurement is performed at the predetermined measurement magnification while referring to the reference measurement data. 2. A shape measuring method which uses a non-contact three-dimensional measuring device to sequentially perform autofocus at each measurement point of an object to be measured to measure a height at a focus position where an in-focus state is achieved. In the first step of determining the in-focus state by executing autofocus at the final measurement magnification for measuring the finally required accuracy at the measurement point of the measurement object, in the first step In the out-of-focus state, autofocus is performed using the reference measurement data obtained by measuring the measurement object at a magnification lower than the final measurement magnification, and the focus becomes the in-focus state. And a second step of detecting a position. 3. The measurement start point is determined by the final measurement magnification, the measurement is started after the measurement start point is aligned at a magnification lower than the final measurement magnification, and the measurement data is measured by the reference measurement. The shape measuring method according to claim 2, wherein the step of acquiring as data is executed before the first step. 4. The second step performs autofocus using the measurement height data of the reference measurement data corresponding to the measurement point when an out-of-focus state occurs in the first step. If it is out of focus, it is automatically measured using the measurement height data of the measurement points located before and after the measurement point from the reference measurement data. 4. The shape measuring method according to claim 2, wherein the process of executing the focus and determining whether or not the focus state is achieved is repeatedly performed a predetermined number of times until the focus position in the focus state is detected. 5. If the in-focus state is obtained even after the processing is repeatedly performed the predetermined number of times, the measurement target is a measurement magnification different from the reference measurement data used in the previous measurement as the reference measurement data. The shape measuring method according to claim 4, wherein reference measurement data obtained by measuring the object is used. 6. A shape measuring device for measuring the shape of an object to be measured at a predetermined measurement magnification, with reference to reference measurement data obtained by measuring the object to be measured at a magnification lower than the predetermined measurement magnification. At the same time, the shape measuring device is provided with means for performing measurement at the predetermined measurement magnification. 7. A shape measuring device for performing height measurement at a focus position where an in-focus state is achieved by sequentially performing auto-focus at each measurement point of the measurement target, wherein the measurement point of the measurement target is measured. In the first means for determining the in-focus state by executing autofocus at the final measurement magnification for finally measuring the required accuracy, in the case of the non-in-focus state by the first means, Is a second means for performing autofocus using reference measurement data obtained by measuring the measurement object at a magnification lower than the final measurement magnification, and detecting a focus position in a focused state. A shape measuring device comprising: 8. The measurement start point is determined by the final measurement magnification, the measurement is started after the measurement start point is aligned at a lower magnification than the final measurement magnification, and the measurement data is measured by the reference measurement. The shape measuring device according to claim 7, further comprising means for acquiring as data. 9. The second means, when the first means is in an out-of-focus state, executes autofocus using the measurement height data of the reference measurement data corresponding to the measurement point. If it is out of focus, it is automatically measured using the measurement height data of the measurement points located before and after the measurement point from the reference measurement data. 9. The shape measuring apparatus according to claim 7, wherein the process of performing the focus and determining whether or not the focus state is achieved is repeatedly performed a predetermined number of times until the focus position at which the focus state is achieved is detected. 10. When the in-focus state is obtained even after the processing is repeatedly executed the predetermined number of times, the reference measurement data is the measurement target at a measurement magnification different from the reference measurement data used in the previous measurement. The shape measuring device according to claim 9, wherein reference measurement data obtained by measuring an object is used. 11. A control program for executing a shape measuring method for measuring a shape of an object to be measured at a predetermined measurement magnification using a non-contact three-dimensional measuring device, the control program being lower than the predetermined measurement magnification. A control program comprising: a step of measuring the measurement object at a magnification to create reference measurement data; and a step of performing measurement at the predetermined measurement magnification while referring to the reference measurement data. 12. A shape measuring method, which uses a non-contact three-dimensional measuring device to sequentially perform auto-focus at each measurement point of a measurement object to measure height at a focus position where a focused state is achieved. Is a control program for executing, the first to determine the in-focus state by executing autofocus at the final measurement magnification for measuring the finally required accuracy at the measurement point of the measurement object. Step, and when the out-of-focus state is obtained in the first step, autofocus is performed using the reference measurement data obtained by measuring the measurement object at a magnification lower than the final measurement magnification. And a second step of detecting a focus position in a focused state. 13. The measurement start point is determined by the final measurement magnification, the measurement is started after the measurement start point is aligned at a magnification lower than the final measurement magnification, and the measurement data is measured by the reference measurement. 13. The control program according to claim 12, wherein the step of acquiring as data is executed before the first step. 14. The second step performs autofocus using the measurement height data of the reference measurement data corresponding to the measurement point when the out-of-focus state is obtained in the first step. If it is out of focus, it is automatically measured using the measurement height data of the measurement points located before and after the measurement point from the reference measurement data. 14. The control program according to claim 12, wherein the process of executing the focus and determining whether or not the focus state is achieved is repeatedly performed a predetermined number of times until the focus position at which the focus state is achieved is detected. 15. If the in-focus state is obtained even after the processing is repeated a predetermined number of times, the reference measurement data is the measurement target at a measurement magnification different from the reference measurement data used in the previous measurement. 15. The control program according to claim 14, wherein reference measurement data obtained by measuring an object is used. 16. A storage medium on which the control program according to claim 11 is stored.