JP2010036315A - End face grinding device of substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grinding device for grinding an end face of a brittle substrate such as a glass substrate. <P>SOLUTION: The end face grinding device includes a grinding wheel of which the peripheral edge part for grinding the end face of the substrate is made by elastic material, and a rotation driving means and feed control means of the grinding wheel. The rotation driving means has a load current detection means for detecting load current flowing while abutting to the end face of the substrate and a validity determination means of the load current value, The feed control means has a notch direction feed control means and a thrust direction feed control means to the end face of the substrate, and notch direction feed operation and thrust direction feed operation of the grinding wheel are controlled based on the validity determination means of the load current value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polishing apparatus for polishing a cut end surface of a brittle substrate such as a glass substrate.

In the case of brittle substrates such as glass, quartz, ceramics, etc., cullet may occur on the cut end face, or cracks may occur starting from micro cracks. The strength is improved.
Conventionally, as shown in FIG. 6, a substrate 102 is placed on a base 103 using a buffing grindstone 101, and polishing is performed by pressing each side.
In this case, the polishing amount was unstable and the number of processes was large.
In recent years, it has been proposed to use a polishing wheel whose peripheral part is rich in elasticity to polish the end face of this kind of hard brittle material into a mirror surface.
As what is marketed, there is a resin in which fibers are filled and abrasive grains are dispersed in this resin.
Such a polishing wheel using an elastic material in the peripheral portion has excellent conformability when the outer peripheral surface of the wheel is brought into sliding contact with the end surface of the substrate, and the mirror finish quality is stable.
However, since it is rich in elasticity, the wear is fast, and a wear groove that is recessed in a concave shape is generated along the contact surface of the substrate.
Therefore, when a predetermined number of substrates are polished, the wear grooves become too deep and the rotational driving resistance of the polishing wheel increases, so that the polishing quality becomes unstable and defective products are likely to occur.
In this case, conventionally, the position where the operator hits the substrate end surface of the peripheral portion of the polishing wheel has been changed.
In this case, the processing line is temporarily stopped for the adjustment, which is one of the factors that decrease the productivity.

  Patent Documents 1 and 2 disclose a technique for adjusting the cutting speed based on the power value of the grindstone drive motor, but do not manage the wear grooves of the grinding wheel.

JP 2004-122259 A Japanese Patent Laid-Open No. 7-171742

  An object of the present invention is to provide a substrate end surface polishing apparatus with high continuous productivity in consideration of the wear amount of a polishing wheel.

  The substrate end surface polishing apparatus according to the present invention includes a polishing wheel having a peripheral edge made of an elastic material for polishing the end surface of the substrate, a rotation driving unit and a feed control unit of the polishing wheel, and the rotation driving unit includes: A load current detecting means for detecting a load current flowing when contacting the substrate and the end face and means for determining the appropriate value of the load current value are provided. And a feed control means, and the cutting direction feed operation and the thrust direction feed operation of the grinding wheel are controlled based on the load current value appropriateness judgment means.

A polishing wheel having a peripheral edge made of an elastic material means that a wheel outer periphery for polishing the end surface of the substrate is at least an elastic material, and abrasive particles are contained in the elastic material.
The abrasive grains are not particularly limited, and examples thereof include diamond abrasive grains, silicon carbide abrasive grains, CBN (cubic boron nitride) abrasive grains, and cerium oxide abrasive grains.
Moreover, the elastic material should just use the structure and material rich in elasticity, and is not limited to what filled the resin into the fiber mentioned above.

As an example of a measure for controlling the cutting wheel direction feed operation and the thrust direction feed operation of the polishing wheel based on the load current value appropriateness determination means, the load current value appropriateness determination means is configured such that the load current value at the time of polishing the substrate end face is When it is determined that the predetermined value has been exceeded, the next substrate end face processing includes a method in which the thrust direction feed control means moves the polishing wheel by a predetermined pitch and starts polishing.
As another example of measures, when the load current value appropriateness determining means determines that the load current value during polishing of the substrate end face is within a predetermined range, the thrust direction feed control means determines the polishing wheel to be predetermined. There is a method of polishing while traversing at a speed of.

Here, moving the grinding wheel by a predetermined pitch means that the wear groove generated in the grinding wheel becomes deep from the load current value detected by the load current detection means provided in the rotation drive means, and cannot be used any more. When the appropriateness determining means determines, the thrust direction feed control means moves the polishing wheel in the thrust direction at least beyond the thickness of the substrate and polishes it at a new peripheral portion.
Therefore, in this case, wear grooves are formed at predetermined pitches on the peripheral edge of the grinding wheel.
On the other hand, in the method of polishing while traversing the polishing wheel at a predetermined speed, the load current value appropriate judgment means is in sliding contact with the edge of the polishing wheel in a state where the peripheral edge of the polishing wheel can be polished. This is a method for polishing the end face of the substrate while traversing the polishing wheel in the thrust direction while confirming the above.
In this case, the peripheral edge of the grinding wheel is worn evenly in the thrust direction.

  In the polishing apparatus according to the present invention, the feed in the cutting direction of the polishing wheel and the thrust are detected and taken into account based on the load current value flowing through the rotational drive unit of the polishing wheel while detecting and taking into consideration the amount of wear generated at the peripheral edge of the polishing wheel. Since the feed of the direction is controlled, continuous machining is possible and productivity is improved compared to the conventional method where the wear groove depth is temporarily stopped and the sliding contact position of the grinding wheel is changed. In addition, the polishing quality is stable.

The inventors first investigated the number of glass substrates polished and the depth of wear grooves appearing on the periphery of the polishing wheel using an elastic polishing wheel (manufactured by Sumitomo 3M Limited, trade name: DLO wheel).
The results are shown in the table of FIG.
As the number of processed sheets increases, the groove depth becomes deeper. When approximately 800 sheets are polished, the groove depth becomes approximately 0.51 mm, and the load current value that flows to the rotational drive portion of the polishing wheel at that time is worn by the polishing wheel. The average was about 20% larger than when no groove was formed.
Further, when the number of polishing processes increases to about 2000, the wear groove depth becomes 1.0 mm, and the load current value at that time is about 40% larger than the average when no wear groove is generated. It was.
From the result of this preliminary investigation, it became clear that the wear groove depth of the grinding wheel can be predicted from the change of the load current value.

Next, an embodiment according to the present invention will be described with reference to the drawings.
FIG. 3 schematically shows the configuration of the main part of the polishing apparatus, and FIG. 4 shows an example of feed control in the cutting direction of the polishing wheel 1 with respect to the substrate 2.
As shown in FIG. 3, the grinding wheel 1 is pivotally supported on a rotary shaft 31 connected to a drive unit having a rotation drive means and a feed control means.
Yes Although illustrated drive unit and a control unit is omitted, the rotational speed W ₁ of the grinding wheel _1, sliding contact with the end face 21 of the substrate 2, the infeed direction feed control means for controlling the feed to the cutting direction (X-axis control) In addition, there is a thrust direction feed control means for controlling the movement of the substrate 2 in the thrust direction (Z-axis control).
Further, the drive unit is provided with load current detection means for detecting a load current value due to a load received by the frictional resistance when the polishing wheel 1 is in sliding contact with the end surface 21 of the substrate 2.

Substrate 2 such as a glass substrate, in the embodiment shown in FIG. 3, while being clamped held between the clamp base 41a of the clamping portion 40a and the lower clamper 41 on the clamper 40 which is vertically moved control, rotate in W ₂ direction It is controlled.
In addition, if the board | substrate 2 is hold | maintained, it will not be limited to a present Example, You may provide an adsorption | suction means in the clamp stand 41a, and may carry out adsorption holding.
In the polishing apparatus according to the present embodiment, as shown in FIG. 4, the rotation of the substrate 2 is controlled. For example, the rotation center O of the polishing wheel is sequentially changed from one corner 2c of the substrate 2 to the side 2b and the other corner 2d. In this example, the polar coordinate system is used to control the movement to O _{1 to} O ₃ , and the entire end face can be polished by rotating the substrate 2 once.
The polishing apparatus according to the present invention is not limited to the present embodiment, and may be XY coordinate system control.

Next, a method for managing wear of the grinding wheel 1 will be described.
FIG. 1 shows the first embodiment, in which only the cross section of the polishing wheel 1 and the vicinity of the end face 21 of the substrate 2 are shown.
When the cutting control is performed to polish the end surface 21 of the substrate 2 by the cutting direction control means (X axis) of the polishing wheel 1, a wear groove d is generated in the peripheral portion 1a made of an elastic material as the number of processed sheets increases.
Since it has been clarified in a preliminary investigation that the load current value of the rotary drive unit increases as the wear groove d becomes deeper, the depth of the wear groove and the quality of the polishing quality are judged based on the increase amount of the load current value. A means for determining the appropriateness of the load current value is provided.
The load current value appropriateness determining means has, for example, a calculation program for calculating the wear groove depth from the change of the load current value, and when it is determined that the depth of the wear groove d is the limit, the thrust direction feed When the control means (Z-axis) starts polishing the next substrate, the control means (Z-axis) moves in the Z-axis direction by the pitch P.
In the example shown in FIG. 1, the polishing wheel 1 is raised by the pitch P from the state of the substrate 2a shown by an imaginary line to the state of the substrate 2 shown by a solid line, but sequentially moves from top to bottom. The method may be used.
The dimension of the pitch P only needs to be larger than the thickness of the substrate 2. In FIG.

In the second embodiment shown in FIG. 2, the polishing wheel 1 is moved in the thrust direction (in the thrust direction) while maintaining the state in which the sliding contact outer peripheral surface of the polishing wheel 1 and the peripheral portion 1a is slidingly polished to the end surface 21 of the substrate 2. In this example, the movement is controlled in the upward direction in FIG.
The feed in the cutting direction is judged and controlled by the load current value appropriate judgment means so that the polishing pressure is within a predetermined appropriate range from the load current value.

The example of the grinding | polishing wheel control method of the grinding | polishing apparatus which concerns on this invention is shown. An example of traverse control of a grinding wheel is shown. The example of a principal part structure of a grinding | polishing apparatus is shown. An example of polar coordinate polishing control is shown. The results of the investigation of the number of substrates polished and wear groove depth are shown. The example of the conventional grinding | polishing method is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polishing wheel 1a Peripheral part 2 Substrate 10 Cutting direction feed control means (X axis)
20 Thrust direction feed control means (Z axis)
30 Rotation drive means

Claims (3)

A polishing wheel having a peripheral edge made of an elastic material for polishing the end surface of the substrate, a rotation driving means and a feed control means of the polishing wheel,
The rotation drive means has a load current detection means for detecting a load current flowing when contacting the end face with the substrate, and an appropriate judgment means for the load current value,
The feed control means has a cutting direction feed control means and a thrust direction feed control means with respect to the end face of the substrate, and the cutting direction feed operation and the thrust direction feed operation of the polishing wheel are performed based on the load current value appropriate judgment means. An apparatus for polishing an end face of a substrate, which is controlled. When the load current value appropriateness determining means determines that the load current value during polishing of the substrate end face exceeds a predetermined value,
2. The substrate end surface polishing apparatus according to claim 1, wherein in the next substrate end surface processing, the thrust direction feed control means moves the polishing wheel by a predetermined pitch and starts polishing processing.   When the load current value appropriateness determining means determines that the load current value at the time of polishing the substrate end face is within a predetermined range, the thrust direction feed control means performs polishing while traversing the polishing wheel at a predetermined speed. The apparatus for polishing an end face of a substrate according to claim 1, wherein:

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