JPH041508A - Inspection method for appearance of electronic component - Google Patents

Abstract

PURPOSE:To eliminate the misdetection of the height of a reflection point due to the secondary reflection of laser beam by providing an xy-directional position detecting element which detects simultaneously the height of the reflection point and the position in a scanning direction. CONSTITUTION:The electronic component is irradiated with the laser beam while scanning it with the laser beam and its reflected light is made incident on the position detecting element to detect the height of the reflection point of the laser beam. As for this appearance inspection method for the electronic component, the laser beam emitted by a laser device 10 is reflected by an electrode part, soldering zone 4, etc., of a lead 2, etc., and made incident on the xy-directional position detecting element 5 to detect the heights of reflection points A-H and also detect the positions of the incidence points xa-xh of the height-detected reflection points A-H in the scanning direction (x). Consequently, when secondary reflected light is made incident on the position detecting element 5, the position of this secondary reflection point in the scanning direction is detected to detect the incident light being a noise, thereby inspecting the appearance of the soldering zone 4, lead 2, etc., with accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for visually inspecting electronic components, and more particularly to means for eliminating erroneous height detection due to secondary reflection of laser light.

(Prior Art) Electronic components mounted on a board are visually inspected to check the quality of the solder shape, misalignment, etc. For this visual inspection, an inspection method using laser spot light is known. There is.

FIG. 2 shows a conventional means, in which 101 is a substrate, 102 is an electronic component lead, which is bonded to a solder portion 104 formed on a circuit pattern 103.

This device irradiates the solder part 104 with scanning laser spot light in the length direction (X direction), makes the reflected light enter a position detection element 105 such as a PSD, and from the incident position, the reflected light The height of the point is detected to determine whether the shape of the solder portion 104 is good or bad.

(Issues to be Solved by the Invention) The laser beam irradiated onto the solder portion 104 is not necessarily all directly reflected toward the position detection element 105, for example at point a.

As shown by the broken line arrow in b, light reflected onto the nearby circuit pattern 103 and secondarily reflected at points a' and b' on the circuit pattern 103 may enter the position detection 105. . In this case, since the surface of the circuit pattern 103 has strong specularity due to solder plating, etc., the laser beam is directed to points a and b.
In that case, the position detection element 105 is likely to be reflected more strongly at the secondary points a'' and b' than at the secondary points a'' and b'.
, b' are easily detected mistakenly as the heights of points a and b, and as a result, the height of the surface of the solder portion 1040 is detected to be much lower than the actual height, as shown by the chain line 107. There was a problem with it.

Secondary reflections that cause such erroneous detection are likely to occur not only in the circuit pattern 103 (but also in specular parts such as the leads 102 and the solder portions 104).

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a solder appearance inspection method that can eliminate erroneous height detection due to secondary reflection of laser light.

(Means for Solving the Problem) The present invention irradiates an electronic component with a laser beam while scanning it, and makes the reflected light enter a position detection element.
In an external appearance inspection method for electronic components in which the height of a reflection point of a laser beam is detected, an xy-direction position detection element is provided as the position detection element to simultaneously detect the height of the reflection point and the position in the scanning direction. By detecting the position in the scanning direction of the reflection point whose height has been detected, it is determined whether the laser light incident on the position detection element is not noise.

(Function) In the above configuration, the laser beam is reflected by the electrode part of the lead, the solder part, etc., and enters the position detection element, and the height of the reflection point is detected, and the height is detected by the reflection point. The position of the point in the scanning direction is detected.

When the laser beam reflected by the solder part etc. is secondarily reflected by the circuit pattern on the side, and the strong secondary reflected light is incident on the position detection element, the scanning direction of this secondary reflection point is By detecting the position, it is detected that this incident light is noise.

(Example) Next, the present invention will be described in detail with reference to the drawings.

In FIG. 1, 1 is a board, and 2 is a lead of an electronic component 8 mounted on the board 1. In FIG. 3 is a circuit pattern formed on a circuit board, the surface of which is solder-plated, and the lead 2 is connected to the circuit pattern 3 by the solder portion 4.
glued on top. Reference numeral 5 denotes an xy-direction position detection element such as a PSD, which simultaneously detects the height (X direction) of the reflection point and the position in the scanning direction (X direction) of the laser beam. 10 is a laser device, II is a mirror, and by rotating the mirror 11 in two directions, the laser device 10
The lead 2 and the solder portion 4 are irradiated with the laser spot light irradiated from the lead 2 and the solder portion 4 while scanning in the xyx directions.

This means directs the laser spot light from the lead 2 to the solder portion 4.
While scanning in the X direction toward The height of the surface of the solder portion 4 is detected and the shape of the solder portion 4 is determined. At that time, the incident point xa in the X direction
By simultaneously detecting the position of ~xh, the reflection point A~
Detect the position of H in the X direction.

By the way, as described above, not all of the laser light irradiated onto the lead 2 or the solder portion 4 is necessarily reflected directly to the position detection element 5, but may be reflected laterally. Reflection points E and F show such cases. The laser light reflected at the reflection points E and F is secondarily reflected at the secondary reflection points E' and F' on the side circuit pattern 3, which are not subject to measurement, and the reflected light is transmitted to the position detection element. It is incident on the incident points e' and f' of No. 5. In this case, since the surface of the circuit pattern 3 is soldered and plated, the laser beam is more strongly secondary at the secondary reflection points E' and F' than at the reflection points E and F due to its specularity. It is reflected, becomes strong noise, and easily enters the position detection element 5. Therefore, the incident points ye' and yf' due to the secondary reflection points E' and F' are mistakenly detected as the heights of the reflection points E and F.

However, since this means simultaneously detects the incident points xe' and xf' in the X direction of this secondary reflection point E''F°, it is possible that these incident points xe' and xf' are different from the correct incident points xe and xf. Since this is detected, the laser light incident on the incident points xe' and xf' is determined to be noise and is excluded from the measurement data.

In this way, in this method, when detecting the incident points ya to yh in the y direction of the laser beam incident on the position detection element 5, at the same time, detecting the incident point Xa - x h in the X direction, Since it is determined whether the detected height is appropriate for the detection position, it is possible to determine whether the laser light incident on the position detection element 5 is normal reflected light reflected from the measurement target point such as a solder part or lead, or It can be appropriately determined whether the noise is secondary reflection from a point other than the measurement target point.

Next, an example of a method for determining the shape of a portion to be measured such as the solder portion 4 when noise due to secondary reflection is detected as described above will be described.

In the above embodiment, noise due to secondary reflection is detected at reflection points E and F. Therefore, by excluding the measurement data of reflection points E and F, the reflection points before and after them, and the incident point d of C.
, g is set, and the line M that connects the reflection point G corresponding to this line m is determined to be the shape between D and 0.

According to this method, although it is not possible to determine the exact height between D and 0, the height between D and 0 can be determined to satisfy a certain degree of accuracy.
The height between 0 and 0 can be easily estimated. Of course, this line m does not necessarily have to be a straight line, but may be a curved line that follows the surface shape of the object to be measured, such as a solder part.

(Effects of the Invention) As explained above, the present invention irradiates an electronic component with a laser beam irradiated from a laser device while scanning it, makes the reflected light enter a position detection element, and points the reflection point of the laser beam. In the external appearance inspection method for electronic components, the position detection element is an xy-direction position detection element that simultaneously detects the height of the reflection point and the position in the scanning direction, and the height of the reflection point is By detecting the position of the detected reflection point in the scanning direction, it is determined whether the laser beam incident on the position detection element is noise or not, so noise due to secondary reflection of the laser beam can be determined. It is possible to accurately perform visual inspections of electronic components such as solder parts and leads.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which FIG. 1 is a perspective view of a solder portion being measured, and FIG. 2 is a side view of a conventional means being measured. 5...xy direction position detection element 8...electronic component 10...laser device A-H...reflection point

Claims (1)

[Scope of Claims] Electronic components are irradiated with a laser beam irradiated from a laser device while scanning, and the reflected light is incident on a position detection element to detect the height of the reflection point of the laser beam. In the external appearance inspection method for electronic components, an xy-direction position detection element is provided as the position detection element to simultaneously detect the height of the reflection point and the position in the scanning direction, and the scanning of the reflection point whose height is detected is provided. 1. A method for inspecting the appearance of an electronic component, characterized in that it is determined whether or not the laser light incident on the position detection element is noise by detecting the position in the direction.