JPS61205808A - Shape detection apparatus - Google Patents

Abstract

PURPOSE:To make it possible to detect the minute three-dimensional shape of a minute object to be inspected, by improving resolving power by enlarging the magnification of an image forming optical system in an X-direction. CONSTITUTION:When laser beam 13 is irradiated around a fillet part 17, the spot image formed onto a unidimensional image sensor 6 corresponds to that the resolving power in an X-direction was relatively reduced by inclining the sensor 6 to the X-direction and the image of the edge part 16 of a lead 10 formed on the sensor 6 heretofore is issued to the outside of the sensor 6 to be formed and only the image of the fillet part 17 appears in the output of the unidimensional image sensor 6 as a peak 15 and the position of the fillet part 17 in a Z-direction can be detected without error. By this method, the shape of even the minute fillet of a solder connection part can be accurately detected.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to detecting minute three-dimensional shapes of connections in soldering of electrical components mounted on a printed circuit board, and in particular,
The present invention relates to a shape detection device suitable for detecting steep minute three-dimensional shapes.

[Background of the invention]

Problems with the conventional device will be explained with reference to FIGS. 1 and 2.

FIG. 1 is a configuration diagram of a detection section of a conventional soldering appearance inspection device. A laser beam emitted from a laser light source 1 is focused into a spot by a focusing optical system 2 onto an object to be inspected 3 placed on an XY table 4. Detect the spot diagonally,
It is comprised of an imaging optical system 5 that forms images on one-dimensional image sensors 6 arranged in two directions.

The operating principle is to obtain two-dimensional detected images of the object to be inspected 3 in the X and Z directions by moving the XY table 4 in the X direction. This detection method is usually called a light cutting method using laser spot light.

FIG. 2 is an example of a minute three-dimensional shape that cannot be detected by a conventional soldering appearance device. Recently, with the progress of miniaturization of electronic components, land 12 on the printed board and lead 1o of electronic components
The fillet of the solder sealing part 11 between them becomes smaller,
The spot diameter has become approximately the same as the spot diameter of the laser beam 13.

The spot diameter of the laser beam 13 is limited by the depth of focus determined by the effective detection range of the object to be inspected 3 in the Z direction, and cannot be made smaller.

Therefore, a spot image 18 is formed on the one-dimensional image sensor 6, and the scanning output is divided into the beak 14 that appears due to regular reflection at the edge portion 16 of the lead 10, and the center of the laser beam 13. A beak 15 due to the reflected light at the fillet portion 17 appears. Originally, since the peak position of the output is detected and the position of the object to be inspected 3 in two directions is detected, when two peaks appear, it becomes difficult to know which is the true peak position. Therefore, in such a case, the shape cannot be detected correctly.

Related devices of this type include JP-A-55-39023 [Optical Displacement Measuring Device], JP-A-56-18707 ``Optical Shape Measuring Method and Apparatus'', JP-A-56 -100306 "Object cross-sectional shape analysis device" etc.

[Purpose of the invention]

An object of the present invention is to provide a means for detecting the minute three-dimensional shape of a minute object to be inspected, whose shape could not be detected conventionally.

[Summary of the invention]

Although it is possible to detect minute three-dimensional shapes by reducing the spot diameter of the laser spot, this cannot be done in order to ensure an effective detection range due to the depth of focus. The present invention is characterized in that the magnification of the imaging optical system in the X direction is increased to improve resolution.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 3 and 5. The configuration shown in FIG. 3 is the same as that of the conventional embodiment shown in FIG. 2, but the difference is that the one-dimensional image sensor 6 is placed tilted in the X direction.

The effect obtained by tilting the one-dimensional image sensor 6 in the X direction will be explained with reference to FIG.

When the laser beam 13 is irradiated centered on the fillet portion 17, the spot image 17 formed on the one-dimensional image sensor 6 can be formed by tilting the one-dimensional image sensor 6 in the X direction. Corresponding to the reduction in resolution, the edge portion 16 of the lead 10, which was conventionally imaged on the one-dimensional image sensor 6, is imaged outside the one-dimensional image sensor 6, and a one-dimensional image is created. The sensor output has a peak 15 only at the fillet portion 17.
Next, another embodiment in which the positions of the fillet portion 17 in two directions can be detected without error will be described with reference to FIG.

In this embodiment, compared to FIG. 2 showing the conventional embodiment, the imaging optical system 5 includes a stone X cylindrical lens 7 that determines the imaging magnification in the 8, each of which is configured to form a spot image of the object to be inspected 3 on the one-dimensional image sensor 6. The imaging magnification in the two directions is determined to satisfy the effective detection range in the Z direction and the required resolution, and
The imaging magnification in the direction is set to satisfy the required resolution in the X direction (
Specifically, the imaging magnification is determined so that the aperture width of the one-dimensional image sensor 6 matches the required resolution.

In this way, the resolution in the X direction can be made small regardless of the magnification in the Z direction, and the position of the minute fillet portion 17 in the Z direction can be detected correctly as in the previous embodiment.

〔Effect of the invention〕

According to the present invention, it is possible to accurately detect the shape of even a minute fillet of a solder joint, which could not be accurately detected in the past.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of the detection optical system of the conventional device, and Figure 2 is:
Principle diagram when shape cannot be detected correctly with conventional equipment, Part 3
The figure is a perspective view showing one embodiment of the present invention, Fig. 4 is a perspective view showing another embodiment, and Fig. wJ5 is a diagram showing the principle by which shape can be correctly detected by the present invention. 1...Laser light source 2...Condensing optical system 3...
Object to be inspected 4...XY table 5...Imaging optical system '10...Lead 11...Solder sealing part
12... Land 13... Laser beam 17.
...Fillet Department Sai 2 Figure O 3 l 4th Kinuta

Claims (1)

[Claims] 1. A focusing optical system that focuses the laser into a spot on the object, the laser light source, and the spot on the object that is detected diagonally and arranged in the same plane as the optical axis of the focusing optical system. It consists of a detection head consisting of an imaging optical system that forms a spot image on a one-dimensional image sensor, and a work table that holds an object. It is a device that scans and detects the spot position on the target object.In particular, it uses a cylindrical lens in the imaging optical system to reduce the resolution in the spot scanning direction, or a one-dimensional image sensor A shape detection device characterized by reducing resolution by placing it at an angle to the object.