JPH04240509A - Apparatus for noncontact measurement of surface shape - Google Patents

Abstract

PURPOSE:To furnish a measuring apparatus enabling noncontact measurement of a surface shape of a lead frame of 0.15 mm or below. CONSTITUTION:A substance 1 to be measured is set on a setting stage and the magnification of an objective lens 2 is so selected as to be matched with the substance. By the magnification of the objective lens, the diameter of a spot of a laser light located on the substance is reduced to the utmost limit. Meanwhile, the laser light 3 is applied along a separate optical axis from the one of a reflected light. The laser light reflected from the substance to be measured is passed through a half mirror 4, reflected by a reflective prism 5 set at an angle of 45 deg. to the substance, measured for its displacement and converted by a differential-type sensor 6 of a photodiode and a laser detector 7 and is recorded in a counter 8, a printer 9 and a recorder 10.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface shape measuring device for soft metals, etc.

0002

2. Description of the Related Art Conventional surface profile measuring machines have been used primarily to measure the roughness of processed surfaces of metals. These measurement methods use a stylus method, in which something like a record stylus is brought into contact with the surface of the object to be measured, and the unevenness of the surface is detected and measured. The stylus type measuring device has a holding mechanism for the detection part, a guiding mechanism which is the feeding device,
It consists of a detection signal processing and recording device.

[0003] In measurement, the shape of the stylus is selected depending on the surface condition of the object to be measured. Next, the measurement conditions are vertical magnification, horizontal magnification (
measurement speed).

[0004] The stylus method has a resolution of 0.5 μm in the vertical direction.
It has been established down to the 0.1 μm level in the lateral direction. Therefore,
Among the conventional shape measurement methods, the stylus method has been evaluated as the most reliable.

Currently, it is used to measure the aluminum thickness of aluminum vapor-deposited frames, the leads of lead frames, and the shape of tab portions.

[0006]

The biggest problem with the stylus method, which is a conventional surface shape measuring method, is the deformation of the surface to be measured due to the load (measuring pressure) on the stylus.

In other words, if the measuring force is F, the mass of the holding mechanism including the stylus is m, the acceleration applied to the stylus is α, and the tracking frequency is f, then

[0008]

[Math 1]

As is clear from these equations, the amount of deformation can be reduced by reducing F, but if m is reduced, followability becomes a problem. Moreover, if α is made small, the measurement time will be too long.

[0010] There is such a problem with the stylus load, and the aluminum vapor-deposited surface and thin lead frame (0.15 mm)
There are limits to the measurement of the following lead shapes, etc., and it is no longer possible to measure the shape.

An object of the present invention is to solve the problems of the conventional stylus method described above, and to provide a measuring device that can measure the surface shape of a lead frame having a shape of 0.15 mm or less in a non-contact manner. .

0012

[Means and effects for solving the problems] The gist of the present invention is to utilize laser light and narrow the light to the ultimate spot diameter.
This is a non-contact surface shape measuring device that irradiates the object to be measured and measures its displacement, making it possible to measure the shape of soft and thin objects.

That is, the above object of the present invention is to provide a stage for placing an object to be measured, a laser light source, an objective lens for minimizing the spot diameter of the laser beam irradiated onto the object to be measured, and a laser beam reflected from the object to be measured. This is achieved by a non-contact surface profile measuring machine characterized by a photodiode differential sensor that receives laser light through a half mirror, and a laser detector that detects the roughness of the machined surface by differential amplification. Ru.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be explained with reference to the block diagram of FIG. First, the object to be measured 1 is placed on the stage of the measuring machine. The magnification of the objective lens 2 is selected according to the object to be measured, and the spot diameter of the laser beam on the object to be measured is narrowed down to the maximum by the magnification of the objective lens. On the other hand, laser light 3 is irradiated from an optical axis different from that of the reflected light. The laser beam reflected from the object to be measured passes through a half mirror 4 and is reflected by a reflecting prism 5 set at 45 degrees with respect to the object to be measured, and the displacement is measured by a photodiode differential sensor 6 and a laser detector 7. , converted counter 8, printer 9, recorder 10
Recorded by

[0015]

Effects of the Invention The non-contact surface profile measuring device of the present invention achieves 1. It is now possible to measure the shape of soft objects.

2. It is now possible to measure the lead shape of thin lead frames (0.15 mm or less).

[Brief explanation of the drawing]

[Fig. 1] 1 of the non-contact type surface profile measuring device of the present invention
FIG. 2 is a block diagram of an embodiment.

[Explanation of symbols]

1 Object to be measured 2 Objective lens 3 Laser beam 4 Half mirror 5 Reflection prism 6 Photodiode differential sensor 7 Laser detector 8 Counter 9 Printer 10 Recorder

Claims (1)

[Claims] Claim 1: A stage for placing an object to be measured, a laser light source, an objective lens for minimizing the spot diameter of the laser beam irradiated onto the object to be measured, and a half mirror for directing the laser beam reflected from the object to be measured. A non-contact surface profile measuring device characterized by comprising a differential photodiode sensor that receives the signal, and a laser detector that detects the roughness of the machined surface by differential amplification.