JP2639236B2 - Lead inspection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead inspection apparatus and, more particularly, to a lead inspection apparatus for detecting the height of a lead of a semiconductor element, the presence or absence of foreign matter on the lead, and foreign matter between leads.

[0002]

2. Description of the Related Art The prior art includes a light projecting lens for condensing a laser beam and a laser beam, a light receiving lens for condensing light reflected from a portion to be measured disposed at a light condensing point, and an image forming point of the light receiving lens. And a height detection circuit that measures the height of the device under test from a height signal and a light amount signal obtained from the one-dimensional light spot position detector. .

Next, a conventional technique will be described in detail with reference to the drawings. FIG. 5 is a perspective view showing an example of a conventional height measuring device, and FIG. 6 is an operation explanatory diagram of the device shown in FIG.

The height measuring device shown in FIG. 5 includes a light projecting lens 33 for condensing a laser 31 and a laser beam 32 on a lead 21 of a semiconductor device 20 and a light receiving lens 34 for condensing light reflected from the lead 21. 1 disposed at the image forming point of the lens 34
It is configured to include a three-dimensional light spot position detector 35 and a height detection circuit 36 for measuring the height of the lead 21 from the height signal H and the light quantity signal P obtained from the one-dimensional light spot position detector 35.

As shown in FIG. 6, when the height of the lead 21 changes, the reflection point of the laser beam 32 changes to A, B, and C.
Further, the images of the reflection points A, B, and C are
An image is formed at the positions of A ₁ , B ₁ , and C ₁ on the three-dimensional light spot position detector. 1-dimensional point position detector 35 outputs the output P _1, P ₂ according to the position of the imaged light spot, P ₁
+ P ₂ becomes the light amount signal P of the light spot, and (P ₁ −P ₂ ) /
(P ₁ + P ₂ ) is the position of the light spot, that is, the lead height signal H.

However, the lead height signal H does not normally change even if the light amount signal P at the light spot changes. However, when the laser beam hits the edge of the lead, the light amount decreases, so that the dark current and the disturbance light are reduced. And the error of the height signal increases. Therefore, a signal having a light amount Th1 or more is effective.

[0007]

The conventional lead detecting device has a problem in that it only detects the height of the lead and cannot detect the presence or absence of foreign matter adhering to the lower surface of the lead. Therefore, there is a problem that the inspection for detecting foreign matter attached to the lower surface of the lead must rely on the visual inspection of an operator. There was a drawback that detection was not possible due to the small number.

[0008]

According to a first aspect of the present invention, there is provided a lead inspection apparatus including a laser and a lens for condensing a laser beam.
A projection optical system for irradiating the measured surface with laser light obliquely, a lens for condensing the reflected light from the measured surface, and a one-dimensional light spot position detection disposed at an image point of the condensed reflected light Vessel and before
The height obtained based on the output from the one-dimensional light spot position detector
Is the signal and the area extracting circuit for cutting a certain light level or more areas on the basis of the light quantity signal among the light quantity signal, foreign object detection area extracting circuit for cutting the area excluding the infinitesimal area around the area extracted in the area extracting circuit When,
Attached to the lower surface of the the height detector to determine the height of the object based on the height signal, the surface to be measured in the area obtained by the foreign object detection area extracting circuit of the area obtained by the area extracting circuit And a lead foreign matter detection circuit for detecting the foreign matter.

According to a second aspect of the present invention, there is provided a lead inspection apparatus comprising: a laser; a lens for condensing laser light on a surface to be measured; a light receiving lens for condensing light reflected from the surface to be measured; A one-dimensional light spot position detector arranged at a point, a moving mechanism for relatively moving the object to be measured and the condensing point, and taking in a height signal and a light amount signal obtained from the one-dimensional light spot position detector Excluding each memory, a first area extraction circuit for extracting an area having a certain light amount level or more, and an area in which a small area is added before and after the first area extracted by the first area extraction circuit. A second area extraction circuit for extracting the second area, a height detection circuit for obtaining the height of the device under test from height information in the first area, and a height detection circuit for calculating the height in the second area. A lead inspection circuit including a foreign matter detection circuit for detecting foreign matter Location.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a first embodiment of the present invention.

The lead inspection apparatus shown in FIG.
And a projection optical system 4 composed of a lens 3 for condensing the laser beam 2
A one-dimensional light spot position detector 6 disposed at an image forming point through a lens 5 for irradiating the lower surface of the lead 7 as a measured surface with the laser beam 2 obliquely and condensing the reflected light; Height signal obtained based on the output from the light spot position detector 6
An area extraction circuit 11 for cutting out an area having a certain light amount level or more based on the light amount signal P among the H and the light amount signal P;
When a foreign object detection area extracting circuit 12 for cutting the area excluding the <br/> infinitesimal area around the area extracted in the area extracting circuit 11, the height signal in the area obtained by the area extracting circuit 1 1 The height detection circuit 9 for obtaining the height of the object to be measured based on H and the foreign matter detection area extraction circuit 12 cut out.
And a lead foreign matter detection circuit 10 for detecting foreign matter attached to the lower surface of the surface to be measured based on the light quantity signal P of the area .

[0012] FIG. 2 (a) ~ (d) is a waveform diagram illustrating the operation of the first invention. FIG. 2A shows a height signal H, and FIG. 2B shows a case where a threshold value th1 is provided in order to remove the influence of electric noise of the light amount signal P obtained from the one-dimensional light spot position detector 6. The light amount signal of a certain level or more is made effective. The effective range of the light amount signal is cut out by the area extracting circuit 1, and the output is shown in FIG.

When the height of the object to be measured is actually obtained, the area obtained by the area extraction circuit 11 may be used. However, when detecting a lead foreign object, the foreign object detection is performed in order to remove the influence of both ends of the lead. FIG. 2 obtained by the area extraction circuit 12
The lead foreign matter detection circuit 10 is activated in the area (d).

The operation of the lead foreign matter detection circuit 10 will be described below. Normally, the light amount signal at the position of the lead 7 is as shown by a signal 13. However, if a foreign substance adheres to the lower surface of the lead 7, the reflected light is reduced, so that the light amount signal P drops like a signal 15 occurs. A threshold value 16 is provided for detection.

In the lead inspection apparatus, the threshold values th1 and th2
Is set, the value of the threshold value th1 is the light amount signal 13
And the threshold value th2 is set to about 10% of the peak value of the light amount signal 13 .

FIG. 3 is a block diagram showing a second embodiment of the present invention. The lead inspection device shown in FIG. 3 captures a height signal H and a light amount signal P obtained from the one-dimensional light spot position detector 6 and outputs a constant light amount from a height memory 112, a light amount memory 111, and a light amount memory 111. An area extraction circuit 113 for extracting an area of a level or higher, and an area extraction circuit 113
And an area extraction circuit 114 for extracting an area excluding an area where a small area is added before and after the area extracted by the above, and height detection for obtaining the height of the lead 7 of the semiconductor element 8 from the height information H in the area. The circuit 15 includes a foreign matter detection circuit 116 for detecting foreign matter from the height information H in the area.

The operation will be described with reference to FIGS. FIGS. 4 (a) and 4 (b) show the focal point by the moving mechanism,
The position of the semiconductor 8 is moved, and the height signal H from the lead 7 and the light amount signal P obtained from the one-dimensional light spot position detector 6 are obtained.
Indicates a state in which the data is taken into the height memory 112 and the light amount memory 111.

The laser beam 2 hits the edge of the lead 7,
Area (1) 1 in which a light amount larger than the light amount level at which the light amount signal P decreases and the error of the height signal H increases.
7 is cut out by the area extraction circuit 113 (FIG. 4C).
Next, the area extraction circuit 114 cuts out the area (2) 18 excluding the area where a minute area equivalent to the focused beam diameter is added to both sides of the area (1) 17 (FIG. 4D). Next, in the height detection circuit 115, only the height signal H in the area (1) 17 is validated from the height memory 112, and the height of the lead 7 is obtained. Further, only the height signal H in the area (2) 18 is made valid from the height memory 112, and a foreign matter 19 (FIG. 4A) such as a solder whisk between the leads 7 is detected.

Small foreign matters 19 such as solder whiskers between the leads have a small amount of reflected light and are generally smaller than the Th1 level, but can be clearly detected as a height signal although the error is large. Therefore, the area between the leads is obtained by the area extraction circuit 114, and foreign matter between the leads can be detected depending on whether or not there is a height signal in the area.

[0020]

The lead inspection apparatus of the present invention has the effect that foreign substances adhering to the lower surface of the leads and foreign substances between the leads can be detected simultaneously with the height detection.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIGS. 2A to 2D are waveform diagrams illustrating the operation of the first invention.

FIG. 3 is a block diagram showing a second embodiment of the present invention.

FIGS. 4A to 4D are waveform diagrams illustrating the operation of the second invention.

FIG. 5 is a block diagram showing an example of the related art.

FIG. 6 is an optical path diagram for explaining the operation of the conventional example shown in FIG.

[Explanation of symbols]

 Reference Signs List 1 laser 2 laser light 3, 5 lens 6 one-dimensional light spot position detector 7 lead 8 semiconductor element 9 height detection circuit 10 lead foreign matter detection circuit 11 area extraction circuit 12 foreign matter detection area extraction circuit 16, 17 threshold value P light quantity signal H height signal

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location H01L 23/50 H01L 23/50 C

Claims (2)

(57) [Claims] A lens for converging a laser beam and a laser beam; a projection optical system for irradiating the surface to be measured with the laser beam obliquely; a lens for condensing light reflected from the surface to be measured; a one-dimensional point position detector which is disposed at the imaging point of the reflected light, resulting et based on the output from the one-dimensional light spot position detector
The height signal and the area extracting circuit for cutting out areas of <br/> above a certain light level on the basis of the light quantity signal among the light quantity signal, the infinitesimal <br/> area around the area extracted in the area extracting circuit a foreign matter detection area extracting circuit for cutting the exception area, the height detector to determine the height of the object based on the height signal obtained area by the area extracting circuit, resulting in foreign matter detection area extracting circuit A lead foreign matter detection circuit for detecting a foreign matter attached to a lower surface of a surface to be measured in a specified area. 2. A laser, a lens for condensing laser light on a surface to be measured, a light receiving lens for condensing light reflected from the surface to be measured, and one-dimensional light arranged at an image forming point of the light receiving lens. A point position detector, a moving mechanism for relatively moving the object to be measured and the converging point, respective memories for taking in a height signal and a light amount signal obtained from the one-dimensional light point position detector, and a constant light amount A first area extraction circuit for extracting an area of a level or higher;
A second area extraction circuit for extracting a second area excluding an area in which a small area is added before and after the first area extracted by the first area extraction circuit, and a high area in the first area. A height detection circuit for obtaining the height of the DUT from the height signal;
And a foreign matter detection circuit for detecting foreign matter from a height signal in the second area.