JPS62272107A - Inspecting method for packaging component - Google Patents

Abstract

PURPOSE:To accurately detect a component and decide its position even on a curved printed board by measuring the curvature state of the printed board previously and moving a line sensor and light beams. CONSTITUTION:The heights of both end parts of an area on the printed board P are measured by using displacement (height) sensors 19 and 20 to measure the curvature state of the board P. Then, slit beams l are generated by a beam unit 10 to illuminate the board P. The unit 10 is fixed on a rotary stage 15 and rotated according to the tilt angle of the board P and the beams l are therefore rotated by the same angle. The beams l on the board P, on the other hand, are passed through an image forming lens 16 in the opposite direction from the incidence direction to form an image on a line sensor 17. The sensor 17 detects only the position of specific height on the board P by the principle of a light cutting method. The sensor 17 is fixed on a stage 18 and moved in parallel from a reference position by distance (d) along an image formation surface according to the curvature quantity (height) of the board P. The sensor 17 detects different heights on the board P by said movement.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Summary] The present invention irradiates a slit-shaped light beam onto a printed circuit board on which components are mounted, and detects the reflected light with a line sensor. In the mounted component inspection method, which inspects the mounted state of components using The above-mentioned line sensor and the above-mentioned light beam are moved to arrange each at an appropriate position, thereby making it possible to correct warpage.

(Industrial Application Field) The present invention is a mounting state of electronic components mounted on a printed board!
The present invention relates to a mounted component inspection method for optically inspecting (for example, presence/absence, positional deviation, etc.).

Currently, with the miniaturization of semiconductor elements and other electronic components,
The density of printed circuit boards is increasing. As the number of printed circuit boards mounted with chip components increases, it is desired to automatically inspect the mounting state of these circuit boards. For this purpose, it is necessary to detect parts accurately and with good contrast.

[Traditional technique]

FIG. 6 shows an optical system related to a conventional mounted component inspection method. In the figure, only a component Q at a predetermined height on a printed board P is detected using the optical cutting method. In other words, place the printed board P on stage 1 with s! The printed board P is irradiated with a slit-shaped light beam (hereinafter referred to as a slit beam) l created by the semiconductor laser 2, the pre-lens 3, and the cylindrical lens 4 while moving the printed board P in the direction of the arrow. Then, only the reflected light from a predetermined height is imaged by a line sensor 6 such as a COD via an imaging lens 5. The mounting state is inspected based on the image thus obtained, that is, the image in which only the component Q of the predetermined height is distinguished from the others.

[Problem that the invention seeks to solve]

Even if the ends of the printed board P are fixed, the printed board P may warp by several degrees. If the printed board P is warped in this way, the vertical position of the component Q may change due to this warping. Also fluctuates. In such a case, the conventional method described above
Because the height that should be detected by the line sensor 6 will deviate,
There are problems in that the component Q of a predetermined height is correctly mounted but it is determined that there is no component, or that an error occurs in the detected position of the component Q, making accurate position determination impossible. Ta.

In view of the above-mentioned problems, an object of the present invention is to provide a method for inspecting mounted components that can accurately detect and determine the position of components without being affected by the warping, even if the printed board is warped. do.

Means for Solving Problem C] In order to solve the above problems, the present invention measures the warpage state of the printed board in advance, and adjusts the parallelism of the line sensor according to the amount of warpage obtained by this measurement. It is designed to move and rotate the slit beam.

[For production]

By moving the line sensor in parallel and rotating the slit beam, the position on the printed board seen by the line sensor and the position of the slit beam on the printed board can be changed at least in accordance with the warping direction of the printed board. . Therefore, if you measure the warped state of the printed board in advance, you can accurately detect and determine the position of parts corresponding to the warped state by simply changing the state of the line sensor and slit beam as described above according to the amount of warpage. You will be able to do this.

〔Example〕

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

Figures 1 (al and b) are a plan view and a front view showing an optical system according to an embodiment of the present invention. In the figure, a printed board P on which a component Q such as a chip component is mounted is placed on a stage. !3! on 11, and perform a mounting inspection while moving it in the direction of the arrow.

First, a slit beam 1 is created by a beam unit 10 formed by integrating a semiconductor laser 12, a collimating lens 13, and a cylindrical lens 14, and this slit beam 1 is irradiated onto a printed board door at an incident angle θ.

Note that the beam UNISO) 10 is fixed on a rotation stage 15, and is rotated by an angle α from a reference position around the optical axis of the slit beam l, depending on the amount of warpage (β) to be described later in the printed board P. It has become. That is, at this time, as the beam unit 10 rotates, the slit beam e also rotates by the angle α.

On the other hand, the slit beam l on the printed board door is imaged by a line sensor 17 such as a CCD via an imaging lens 16 from a direction opposite to the direction of incidence and at an angle φ with respect to the vertical direction. At this time, the line sensor 17
Based on the principle of optical cutting, only the position at a predetermined height above the printed board door is detected. Note that the line sensor 17 is at stage 1.
8, and is adapted to be moved in parallel by a distance d from the reference position along the imaging plane according to the amount of warpage (h) of the printed board P, which will be described later. This movement allows the line sensor 17 to detect different heights above the printed board door.

In addition, when performing the above-mentioned detection with the line sensor 17,
The heights of both ends A and B of the area above the printed board door to be detected are measured in advance using two optical displacement (height) sensors 19 and 20. The displacement sensors 19 and 20 use light sources 19a and 20a to shine a light beam onto the printed board door from directly above, and use sensors 19b and 20b to detect the height of the light beam when viewed diagonally from above. Perform measurements using trigonometry. In this way, the heights of the two points on the printed board door are measured by the displacement sensor 19.2.
By detecting at 0, the warp state between the two points is measured.

Hereinafter, a specific method of determining the amount of warpage based on the above measurement will be explained.

First, as shown in Figure 2, an arbitrary point on the printed board P is set as the origin 0, the y-axis is in the direction of movement of the printed board P, the X-axis is in the direction perpendicular to the direction of movement, and the two axes are in the height direction. Set coordinates. In this case, the displacement sensor 19.2
The measurement position based on 0 is the part where x = A % B.

An example of the measurement results when x=A or B is shown in FIG. In the same figure, if there is a part on the printed board door along x = A or B, that part (a, b, c) will be measured high, so ignore the part where the height suddenly increases like this, Interpolate as shown by the dashed line.

From the measurement results of the two displacement sensors 19 and 20 obtained in this way, the amount of warpage of the printed board P in any X2 plane can be determined as follows. Note that although the printed board P is generally curved, the warp between A and B, which is relatively narrow, can be approximated by a straight line.

Therefore, the measured values at x = A and B are respectively z (
A, y) and z' (B, y), the warpage between them can be obtained by connecting the above two measured values with a straight line, as shown in FIG. This straight line is expressed by the following equation (11), assuming that the height of an arbitrary position between A and B is z (x, y).

z (x, y) = S x + z (A, y) - A
S ------- (1) In this way, when the warp between A and B is approximated by a straight line, the amount of warp is calculated based on the reference plane at the intermediate position between A and B, as shown in Figure 5. (xy plane)
It is determined by the height h (Y) from the line and the inclination angle β (y) of the straight line. Such warpage 1h(y) and β(y) are functions of the y position of the printed board P, and can be expressed by the following equations (2) and (3) using the above equation fll.

Then, as explained in FIG. 1, the positions of the line sensor 7 and the slit beam l are corrected based on the warpage ih (y) and β(y). The amount of correction, that is, the parallel movement distance d of the line sensor 7 and the rotation angle α of the slit beam l can be determined as follows.

First, as shown in Fig. 5, if we newly set coordinates (x', ', z') with the origin ○ at the intermediate position between A and B, the line sensor 8's line of sight after position correction is , the warpage of the printed board P (linear approximation), and the slit beam surface can be expressed by the following equations (4), (5), and (6), respectively.

z ” w-tanβ-x ′ + h −−−−1・
...------------(5) cos θ, y'
−5inθ−z′=tanα・X′・・−1−−−・
(6) In the above formula (4), L is the distance from the detection target to the imaging lens 16, and L2 is the distance from the imaging lens 16 to the line sensor 7, as shown in FIG.

Then, by making the above equations (4), (5), (5), and (6) equal, distance d and rotation angle α
is obtained. These are shown in equations (7) and (8).

α=jan-' (tanβ・(tanφ−cosθ
+sinθ)), ----+81 formulas (7), (8)
It can be seen that d changes according to h, while α changes according to β. That is, when the amount of warpage of the printed board P is (h, β), if the positions of the line sensor 17 and the slit beam l are corrected according to the above d and α, even if there is warpage, it will not be affected by the warp ( , the appropriate height can always be detected.

Also, the slit beam at this time! The line of intersection between P and the printed circuit board P is projected onto the x'y' plane as shown in Equation 9 (9) below.
It is expressed as

y′=tanφ・tanβ・y, '+h−tan
θ −−−−−−−<q> This corresponds to the detection position of the line sensor 17. Therefore, if the printed board P is warped, a position different from the board position (y'-0) (i.e., the position expressed by equation (9)) will be detected,
Therefore, by correcting this amount when determining the position, accurate determination becomes possible.

〔Effect of the invention〕

According to the present invention, even if the print is warped, it is possible to correct the warp by arranging the line sensor and slit beam at appropriate positions according to the warped state. Accurate component detection and position determination can be performed without being affected by

[Brief explanation of drawings]

FIG. 1(a) and Tbl are a plan view and a front view showing an optical system according to an embodiment of the present invention, FIG. 2 is a diagram showing an example of coordinates set on a printed board, and FIG. 3 is a diagram showing an example of coordinates set on a printed board. , a diagram showing an example of the height measurement results by the displacement sensor, Figure 4 is a diagram showing an example of the warpage (linear approximation) of the printed board obtained by measurement, and Figure 5 shows the amount of warpage of the printed board. FIG. 6 is a front view showing an optical system according to a conventional method. 10... Beam unit, 12... Semiconductor laser, 13... Collimating lens, 14... Cylindrical lens, 15... Rotating stage, 16... Imaging lens, 17... Line sensor, 18... Stage, 19.20... Displacement sensor, l... Slit beam (slit-shaped light beam). Patent Applicant: Fujitsu Limited (a) Plan view Figure 2 Figure 3 Pickling mode ->Tne called Hat: and (straight gland) Fu0 Risotka moxibustion moon Lit htβ Figure 5

Claims (1)

[Claims] 1) A slit-shaped light beam (l) is irradiated onto a printed board on which components are mounted, and reflected light from a predetermined height on the printed board is directed in a direction different from the direction of the irradiation. In the mounted component inspection method of inspecting the mounted state of the component having the predetermined height by taking an image from a direction with a line sensor (17), the warped state of the printed board is measured in advance, and the warped state obtained by the measurement is A mounted component inspection method characterized in that the line sensor is translated in parallel and the light beam is rotated depending on the amount of warpage. 2) The slit-shaped light beam is a semiconductor laser (12)
The laser beam output from the collimating lens (13
) and a cylindrical lens (14). 3) The light beam is rotated by integrating the semiconductor laser, the collimating lens, and the cylindrical lens and fixing them on a rotation stage (15), and rotating the rotation stage. The mounted component inspection method described in Scope 2. 4) Parallel movement of the line sensor is performed by fixing the line sensor to a parallel movable stage (18) and moving the stage in parallel. The method for inspecting a mounted component according to any one of paragraphs. 5) The warped state of the printed board is measured using two optical displacement sensors (19
, 20) and detecting the difference in height between the two points on the printed board using the displacement sensor. Mounted component inspection method described in . 6) Claim 5, wherein the displacement sensor measures the height of the printed board using trigonometry.
Mounted component inspection method described in section. 7) The warped state of the printed board is approximated by a straight line obtained by connecting two points whose heights are detected by the displacement sensor.
Mounted component inspection method described in section. 8) The amount of warpage is expressed by a height (h) with respect to a predetermined reference plane at an intermediate position between the two points of the straight line and an inclination (β) of the straight line. The mounted component inspection method described in Section 7. 9) The line sensor is moved in parallel based on the height of the intermediate position with respect to the reference plane, and the light beam is rotated based on the inclination of the straight line. Mounted parts inspection method. 10) The mounted component inspection method according to any one of claims 1 to 9, wherein the component is a chip component.