JPH0595038A - Bonding wire loop height measuring device - Google Patents

Abstract

PURPOSE:To measure a loop height of a bonding wire in a short time with high precision and in line by a method wherein laser beams are two- dimensionally applied to the side surface of the bonding wire for scanning and the applied light is detected by a light detecting element via the bonding wire. CONSTITUTION:Laser beams from a semiconductor laser 1 are made parallel by a collimating lens 2, these are applied for scanning in the X-axis direction by a rotary mirror 3, and further these are applied for scanning in the y-axis direction by a rotary mirror 6 through relay lens 4, 5. These are applied to the side surface of a bonding wire 10 via a light-emitting lens 7 and a rectangular prism 8, and laser beams 9 obtained through the bonding wire 10 are oriented in the vertical direction through an rectangular prism 12 and made incident on a light-receiving lens 13. These are sent into a phototransistor 14 arranged in a focusing location to detect a condition of interception/passage of the laser beams 9 by the bonding wire 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for measuring a loop height of a wire, and more particularly to a technique effective for measuring a loop height of a bonding wire in wire bonding.

[0002]

2. Description of the Related Art Conventionally, a high magnification microscope has been used to meet the demand for measuring the loop height of a bonding wire. In this case, the microscope is equipped with a rotary encoder that outputs an electric signal according to the amount of lens movement, focuses on two points, the highest point and the lowest point of the loop, and uses the rotary encoder to measure the lens movement amount in the Z-axis direction. It is done by reading.

[0003]

According to the study by the present inventor, the loop height is measured from the lens movement amount in the Z-axis by focusing on the highest point and the lowest point of the loop using a microscope. The technique has a problem that it takes a long time for measurement and in-line measurement cannot be performed because all operations are performed manually.

Therefore, an object of the present invention is to provide a technique capable of measuring the loop height of a bonding wire in-line in a short time and with high accuracy.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0006]

Among the inventions disclosed in the present application, a brief description will be given to the outline of typical ones.
It is as follows.

That is, scanning means for two-dimensionally scanning the light beam from the laser light source toward the side surface of the bonding wire, a lens for focusing the light beam obtained through the bonding wire at a predetermined position, and A light detecting element arranged at the focal position of the lens is provided.

[0008]

According to the above means, the light beam from the laser light source is scanned in the x-direction and the y-direction, and the two-dimensional scanning light is irradiated toward the side surface of the bonding wire and blocked by the bonding wire. The light beam that has not been incident is incident on the photodetection element through the lens, and the loop height of the bonding wire is calculated based on the detection state and the scanning content. Therefore, the loop height of the bonding wire can be measured in-line with high accuracy in a short time.

[0009]

1 is a perspective view showing an embodiment of a bonding wire loop height measuring device according to the present invention.

A semiconductor laser 1 (laser light source) for generating a laser beam is provided with a collimator lens 2 on the emission optical path, and a rotary mirror 3 for performing optical scanning in the x-axis direction is provided on the emission optical path. ing. Relay lenses 4 and 5 are sequentially arranged on the outgoing optical path of the rotary mirror 3, and a rotary mirror 6 for scanning the incident light in the y direction is provided at an image forming position on the outgoing optical path of the relay lens 5. ing. A light projecting lens 7 is arranged on the outgoing light path of the rotary mirror 6, and a right-angle prism 8 for reflecting the incident light in the horizontal direction is arranged on the outgoing light path.

The bonding wire 10 to be measured is placed on the optical path of the laser beam 9 emitted from the rectangular prism 8.
Is located, and one end of the bonding wire 10 is connected to the pellet 11.

A right-angle prism 12 is arranged on the exit optical path of the right-angle prism 8 and a light-receiving lens 1 is arranged on the exit optical path.
3 is provided, and the phototransistor 14 is provided at the image forming position.
(Photodetection element) is provided.

In the above structure, the laser light emitted from the semiconductor laser 1 is collimated by the collimator lens 2, and the emitted light is scanned in the x direction (horizontal direction) according to the rotation of the rotary mirror 3. This scanning light is imaged on the rotating mirror 6 by the relay lenses 4 and 5, and further, the rotating mirror 6
Scanning is performed in the y direction (vertical direction). At this stage, the laser light output from the semiconductor laser 1 is two-dimensionally swung in the x and y directions.

Then, the light emitted from the rotating mirror 6 is incident on the right-angle prism 8 through the light projecting lens 7 and is reflected in the horizontal direction. The bonding wire 10 and the pellet 11 are arranged within the height range of the laser beam 9 emitted from the rectangular prism 8, and the rotating mirror 3 and the rotating mirror 6 are provided.
The laser beam 9 can be two-dimensionally applied to the entire length of the bonding wire 10 by scanning.

The right-angle prism 1 in which the laser beam 9 emitted from the right-angle prism 8 is installed on the opposite side of the pellet 11.
Then, the light is taken out via the light receiving lens 13, and the light receiving lens 13 forms an image on the phototransistor 14. When there is no obstacle between the right-angled prism 8 and the right-angled prism 12, the laser beam 9 reaches the phototransistor 14. On the other hand, when there is an obstacle, the laser beam 9 is reflected by the surface of the obstacle in all directions and does not reach the phototransistor 14.
Thus, by observing the detection signal of the phototransistor 14, the two-dimensional position of the bonding wire 10 can be detected. By processing this with an arithmetic processing unit (not shown) based on the relationship between the scanning angle and the presence or absence of light detection, the maximum value and the minimum value of the loop height can be obtained, and the loop height can be represented by a numerical value. It will be possible.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the embodiments and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, instead of a semiconductor laser, He-Ne
It is also possible to use a gas laser such as. Further, a rotating polygon mirror may be used instead of the rotating mirrors 3 and 6, and a penta prism, a plane mirror or the like may be used instead of the rectangular prisms 8 and 12.

Further, in the above description, the case where the invention made by the present inventor is mainly applied to the measurement of the loop height of the bonding wire, which is the field of application thereof, has been described, but the present invention is not limited to this. For example, it can also be used for inspecting the outer shape of a minute object.

[0019]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.
It is as follows.

That is, scanning means for two-dimensionally scanning the light beam from the laser light source toward the side surface of the bonding wire, a lens for focusing the light beam obtained through the bonding wire at a predetermined position, and Since the photodetector is provided at the focal position of the lens,
The loop height of the bonding wire can be measured inline in a short time, in a non-contact manner, with high accuracy, and at low cost. In addition, the system can be downsized.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a bonding wire loop height measuring device according to the present invention.

[Explanation of symbols]

 1 Semiconductor Laser 2 Collimating Lens 3 Rotating Mirror 4, 5 Relay Lens 6 Rotating Mirror 7 Light Emitting Lens 8 Right Angle Prism 9 Laser Beam 10 Bonding Wire 11 Pellet 12 Right Angle Prism 13 Light Receiving Lens 14 Phototransistor

Claims (3)

[Claims] 1. A scanning means for two-dimensionally scanning a light beam from a laser light source toward a side surface of a bonding wire, a lens for forming an image of the light beam obtained through the bonding wire at a predetermined position, A bonding wire loop height measuring device, comprising: a photodetector disposed at a focal position of a lens. 2. The bonding wire loop height measuring apparatus according to claim 1, wherein the scanning means includes two rotating mirrors for scanning the laser beam in the x direction and the y direction. 3. The bonding wire loop height measuring apparatus according to claim 1, wherein the photodetector is a phototransistor.