KR20060125485A - Polishing grindstone - Google Patents

Abstract

A polishing grind stone is provided to improve polishing uniformity and pressure response by using a rubber sponge having a small hardness and a high repulsive elasticity and residual load. A polishing grind stone comprises a cylindrical core(1); a porous elastic member(2) arranged on the cylindrical core; and a polishing layer(4) formed on an outer circumference of the porous elastic member. The porous elastic member is a rubber sponge having a rubber hardness of C-scale 5 to 40 and a repulsive elasticity 50 to 90%. The rubber sponge has 25% compression load 0.010 to 0.200 MPa specified by JISK6767.

Description

Grinding Wheels {POLISHING GRINDSTONE}

1 is a cross-sectional view showing a schematic configuration of a grinding wheel;

2 is a plan view showing a schematic configuration of a grinding wheel;

3 is a cross-sectional view showing an example of a grinding method using a grinding wheel;

4 is a conceptual diagram illustrating a method for measuring rebound elasticity of a porous elastic body;

5 is a conceptual diagram showing a method for measuring a 25% compressive load value of a porous elastic body;

Figure 6 is a photograph substitute of the back side of the workpiece with the tape attached to the back to make the unevenness,

7 is a photographic substitute for the workpiece after polishing by the whetstone of Example 1,

8 is a photographic substitute for the workpiece after polishing by the whetstone of Comparative Example 1;

9 is a photographic substitute for the workpiece after polishing by the whetstone of Comparative Example 2. FIG.

※ Explanation of code for main part of drawing

1: core material 2: porous elastomer

3: reinforcing layer 4: polishing layer

5 Pressing Head 6 Test Piece of Porous Elastic Body

7: Lower side 8: Pressurization direction (upper to lower)

9: pressurized return direction (bottom to upper) 10: steel ball

11: direction of spindle rotation 12: force of grinding wheel

13: plate-like workpiece 14: back-up roll

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grinding wheel for polishing a plate-shaped workpiece, and more particularly, to a grinding wheel for polishing a metal plate or a nonmetal plate, for example, a polishing of a printed wiring board.

Background Art Conventionally, grinding wheels disclosed in Japanese Patent Laid-Open Nos. 2001-315064 and 2004-50400 are known as grinding wheels for plate-shaped workpieces represented by printed wiring boards.

As an example of a grindstone used for polishing a plate-like workpiece, a porous elastic body 2 is provided on a cylindrical core 1 as shown in FIG. 1, and the reinforcing layer 3 is formed on the outer periphery of the porous elastic body 2. It has a structure which provided the abrasive | polishing layer 4 through this. As for the material of the cylindrical member, for example, a light and rigid material such as a so-called phenol tube hardened by impregnating a phenolic resin into a paper tube is used, and at least one porous elastic body is provided on the outer circumference thereof.

Conventionally, as a porous elastic body, the sponge material which foamed synthetic resin is used. If necessary, a rubber layer reinforced with a reinforcing layer, for example, fiber or metal wire, is provided around the outer periphery of the porous elastic body, and a polishing layer is provided thereon. Typically, the polishing layer is composed of a group of grindstone pieces cut into a block shape as shown in FIG. 2 and a support layer such as a rubber sheet for bonding and holding a group of grindstone pieces.

An example of the grinding | polishing operation | work using the said grinding wheel is shown in FIG. 3 (The grinding wheel is shown by the partial cross section). The grindstone is composed of a cylindrical core 1, a porous elastic layer 2 and a grindstone piece 4 on the support layer 3, which is installed on the main shaft of the polishing machine and driven to rotate in the direction of the arrow 11. . The printed circuit board 13 of the workpiece is sent onto the back-up roll 14 which faces the grinding wheel and rotates in the forward direction. Since the moving speed in the circumferential direction of the polishing layer 3 exceeds the workpiece conveyance speed sufficiently, the surface of the printed board 13 sent between the polishing layer 3 and the backup roll 14 is polished.

[Patent Document 1]

Japanese Patent Application Laid-Open No. 2001-315064

[Patent Document 2]

JP 2004-50400 A

However, there is a problem that sometimes unacceptable grinding irregularities are observed on the to-be-polished surface of a workpiece polished by a conventional grinding wheel. As a reason, the plate-shaped workpiece represented by the printed wiring board has a surface that is not uniform in thickness but has wavy irregularities, and in the case of grinding using a backup roll as described above, the surface of the backup roll has irregularities. Can be mentioned. If the abrasive layer of the abrasive grindstone is not compatible with the irregularities of the plate-like workpiece during polishing, and a portion not sufficiently polished along the surface remains, polishing nonuniformity occurs. Therefore, it is important that the grinding wheel can follow the irregularities of the plate-like workpiece during polishing.

In the two prior arts, the problem of grinding nonuniformity is considered, but the response is insufficient. In the prior art, in particular, improvements in the reinforcing layer correspond to the polishing unevenness. Moreover, some measures have been advanced by actually changing a design about the part of an abrasive layer. However, even that did not sufficiently resolve the polishing irregularity.

Another problem is also pointed out in the abrasive grindstones of this field. In some cases, the grinding pressure at the time of polishing may be changed, but at that time, the removal amount of the workpiece increases or decreases in proportion to the increase or decrease of the grinding pressure, that is, the responsiveness of the removal amount to the grinding pressure (hereinafter referred to as "pressure response"). Is required). When the grinding pressure is increased, the grinding efficiency does not improve unless the amount of removal of the workpiece increases accordingly.

In view of the above problems, an object of the present invention is to provide a grinding wheel for polishing a plate-shaped workpiece, in which grinding irregularity does not occur and has good pressure responsiveness.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, the present inventors focused on the function of the porous elastic body which occupies most of the cross-sectional area of the grinding wheel, and found that it was surprisingly effective to use a rubber sponge as a porous elastic body, and completed this invention.

That is, the present invention is a grinding wheel provided with a porous elastic body on a cylindrical core material and a polishing layer provided on the outer circumference of the porous elastic body, wherein the porous elastic body is a rubber sponge, characterized in that it provides a grinding wheel. do.

Moreover, it is preferable that the said rubber sponge is 5-40 in rubber hardness C scale of a rubber hardness meter, and 50-90% of rebound elastic modulus. Moreover, it is preferable that the said 25% compression load value of the said rubber sponge prescribed | regulated by JISK6767 is 0.010-0.200 MPa.

What is required of a grinding wheel at the time of grinding | polishing is a "soft" characteristic with respect to the load applied to grinding | polishing, ie, the load applied to grinding | polishing even at low grinding | polishing pressure. Doing so can quickly fuse to the unevenness of the plate-shaped workpiece with unevenness. It is also considered that not only the soft but also the residual load with respect to the load is high and the repulsive force (high resilience) is required. If it is soft to some extent and the residual load and the repulsive force are raised, it is considered that the difference in the amount of polishing between the concave portion and the convex portion on the workpiece is eliminated and is polished uniformly. From this point of view, a rubber sponge is used for the porous elastic body which occupies a relatively large volume in the grindstone material.

The rubber sponge used in the present invention is defined as a relatively flexible rubber member in a porous shape obtained by foaming a rubber material without losing high elasticity, which is characteristic of rubber. The rubber sponge which can be used for this invention includes the following, for example.

A) Rubber sponge whose main ingredient is foamed natural rubber and styrene butadiene rubber

Natural rubber is structurally made of sap (latex) from a rubber tree called Hevea brariensis grown in Southeast Asia mainly from polyisoprene.

B) Rubber sponge whose main ingredient is chloroprene rubber

Chloroprene rubber is a synthetic rubber well-known by the name of neoprene, and is a chloroprene polymer represented by the following general formula (1).

C) Rubber sponge whose main component is foamed ethylene rubber

Ethylene propylene rubber is a copolymer of ethylene and propylene or ethylene and propylene and a third component, and is represented by the following general formula (2).

D) Rubber sponge foamed with a copolymer of butadiene and acrylonitrile

E) Rubber sponge which foamed rubber which made siloxane bond skeleton

As mentioned above, although the typical thing was illustrated as a rubber sponge, it is not limited to these, Various rubber sponges known to those skilled in the art can be used for this invention.

Next, the characteristic value of the rubber sponge suitable for this invention is shown with a definition.

Rubber Hardness (Soft)

Rubber hardness in this invention is defined as the hardness of the rubber sponge measured by a rubber hardness meter (C scale).

Rebound modulus

A resilience modulus is a repulsion force of a rubber sponge. The test method of resilience modulus in this invention applies the test method of JISK6255 to the measurement form shown in FIG.

(1) preparing a 1/4 inch steel ball for measuring Rockwell hardness;

(2) install the specimen;

(3) drop a 1/4 inch steel ball from the height of 200 mm from the test piece;

(4) measure the height of the 1 / 4-inch steel ball against the test piece;

(5) Calculation formula: It is calculated by the resilience modulus = height (measured value mm) / height before falling (200 mm) x 100.

25% compressive load value

A compressive load value is a residual load at the time of compressing by applying a predetermined load to the rubber sponge. The 25% compression load value in the present invention is defined according to the test method of JIS K 6767. That is, the test sequence of 25% compression load employs the measurement format shown in FIG. 5;

(1) compressing the sponge specimen to about 25% of the thickness at a compression rate of 10 mm / min;

(2) the load N after 20 second hold was measured;

(3) Calculation formula: 25% compressive load = (1) measured load (N) / cross-sectional area of the sponge test piece (mm2) to obtain.

The characteristic value of the rubber sponge suitable for the grindstone of this invention is as follows.

5-40 are preferable, as for hardness, 7-30 are more preferable, 8-25 are more preferable, and 10-20 are the most preferable. If the hardness is less than 5, the porous elastic body is excessively depressed and the pressure responsiveness to the polishing pressure is deteriorated. In particular, the grinding efficiency does not improve when the polishing pressure is increased. If the hardness exceeds 40, the porous elastic body becomes too hard, resulting in uneven polishing.

The 25% compression load value is preferably 0.010 to 0.200 MPa, more preferably 0.015 to 0.150 MPa, still more preferably 0.020 to 0.100 MPa, still more preferably 0.025 to 0.085 MPa, and most preferably 0.030 to 0.060 MPa. If the 25% compression load value is less than 0.010 MPa, the pressure response when the polishing pressure is changed is poor. If the 25% compressive load value exceeds 0.200 MPa, the porous elastic body becomes hard, resulting in poor pressure responsiveness to polishing pressure and polishing nonuniformity.

50-90% is preferable, 50-80% is more preferable, and 55-75% of the resilience modulus is the most preferable. If the rebound modulus is less than 50%, the pressure response to the polishing pressure is deteriorated and polishing nonuniformity also occurs. In particular, the pressure response when the polishing pressure is increased is worse. On the other hand, rubber sponges with a rebound modulus of more than 90% are generally difficult to manufacture and are considered to be 90% or less.

The material used for the grinding | polishing layer of the grindstone of this invention should just be generally used by the grinding wheel. Generally, the grindstone particles used may be at least one selected from the group consisting of alumina-based grindstone particles, silicon carbide-based grindstone particles, zirconia-based grindstone particles, cerium oxide, silica, chromium oxide, CBN grindstone particles and diamond grindstone particles. The combination is appropriately selected according to the conditions of grinding and the like and the material of the abrasive.

The binder to be used in the polishing layer may be appropriately selected from vitrified, resinoid, PVA or silicate binders. In the case of the vitrified binder, the composition after calcining or curing has a porosity of 10 to 50%, preferably 15 to 45%, and a grindstone particle rate of 30 to 55%, preferably 35 to 50%. In the case of the resinoid binder, the porosity is 0 to 20%, preferably 0 to 10%, and the grindstone particle rate is 20 to 45%, preferably 20 to 40%. In the case of the PVA binder, the porosity is 20 to 50%, preferably 30 to 50%, and the grindstone particle rate is 20 to 45%, preferably 20 to 40%. In the case of the magnesia binder, the porosity is 0 to 20%, preferably 0 to 10%, and the abrasive grain rate is 20 to 40%, preferably 20 to 40%. If the grindstone particle rate is low, the polishing property deteriorates, and if the grindstone particle rate is high, clogging may occur. Binder ratio is 100% minus porosity and grindstone fraction. The degree of selection of the binder is appropriately selected depending on the degree of crystallinity of the whetstone composition, the conditions such as polishing, the material of the abrasive, and the like.

The grindstone of this invention has at least 3 layers of a core material, a porous elastic body layer, and a grinding | polishing layer. In addition, a reinforcing layer may be provided separately between the porous elastic layer and the polishing layer.

The specific structure of the polishing layer may be, for example, a form in which a plurality of segmented grindstones are attached, or a form in which a plurality of small block-shaped grindstones are attached as shown in FIG. 2. The polishing layer can be considered in various forms depending on the grinding conditions, and is not limited to a specific form as long as the flexibility of the polishing layer can be secured. For example, the abrasive layer can be prepared by attaching a whetstone piece on a rubber sheet, and wound it around a porous elastic body or around the outer periphery of the reinforcing layer on the porous elastic body. The thickness of the abrasive layer is preferably 0.5 mm to 5 mm when using CBN grindstone or diamond grindstone particles, and 3 mm to 15 mm when using grindstone particles other than CBN grindstone particles or diamond grindstone particles.

A rubber sheet can be used for a reinforcement layer, the rubber sheet in the grinding | polishing layer to which a grindstone piece is fixed may be used, and a rubber sheet separate from a grinding | polishing layer may be used. The reinforcing layer supports the grindstone pieces so as to have the desired strength and some flexibility to the grindstone during polishing. The reinforcing layer is preferably a structure in which some reinforcing material is embedded in the rubber sheet. Specifically, the structure which embedded the fiber is mentioned. As the structure of the fiber embedding is disclosed in Japanese Patent Laid-Open No. 2004-50400, the reinforcing layer can be configured to have one or more of the above fiber layers inside the rubber sheet layer.

A typical reinforcing layer consists of a rubber sheet fixed on the outer periphery of the porous elastic body and fibers provided inside the rubber sheet. When the fibers inside the rubber sheet are fixed to the grindstone, it is preferable that they are provided in at least two spiral directions that intersect each other about the grindstone rotational axis. In addition, it is more preferable if the fiber parallel to the grinding wheel rotational axis direction is provided. In particular, the fibers have three directions, each of which is about + 60 ° to + 80 °, about + 5 ° to -5 °, and about -60 ° to -80 ° with respect to the grinding wheel rotation axis direction, respectively. Is preferably. It is also particularly preferred that the fibers have three directions and the three directions are angles of about + 75 °, about 0 ° and about -75 ° respectively with respect to the grindstone rotational axis direction.

In addition, the material of the fiber used may be organic or inorganic. Such organic fibers can be selected from the group consisting of aramid fibers, polyester fibers, Kepler fibers, or nylon fibers. Moreover, the structure which wound the metal wire which consists of the single wire | line | wire which carried out the new column plating or the braided piano wire etc. on the outer side of a rubber sheet, and was inserted into the said sheet of the same quality from the outer side, and may be adhere | attached, may be sufficient as it. The metal wire is wound in a spiral shape in the direction of the axis of rotation of the cylindrical grindstone (the direction perpendicular to the surface of the drawing). The selection of the reinforcing material of the reinforcing layer is appropriately selected depending on the conditions such as grinding and the material of the abrasive.

(Example)

The abrasive grindstone of the structure of FIG. 1 and FIG. 2 was produced using the sponge material from which the following material differs for the porous elastic layer, and the grinding | polishing nonuniformity and the pressure response were tested.

Example 1 Rubber Sponge Material of Innoax Products "C-4205"

Comparative Example 1: Polyethylene sponge material of Sekisui Chemical Co., Ltd. "Soft Loan # 40"

Comparative Example 2: Polyethylene sponge material of Sekisui Chemical Co., Ltd. "Soft Loan # 30"

(Characteristic value of sponge material)

The hardness, 25% compression load, and rebound elastic modulus of each sponge material were measured as follows. Hardness was measured with a rubber durometer (C scale) according to the above definition. The 25% compressive load value was measured by Shimadzu Corporation "Autograph AG-10TD" using a 127 x 35 mm rectangular parallelepiped specimen cut out of the sponge material according to the above definition, with the 127 x 35 mm surface as the compressed surface. . Rebound modulus was measured according to the above definition.

(Grinding layer production order)

100 parts by weight of green silicon carbide grindstone particles (GC grindstone particles; particle size 800) as a grindstone particle and 18.0 parts of powdered phenolic resin as a binder were mixed uniformly, and the mixed material was then polished to 60 × 240 mm and 9 mm thickness. Cold forming into shape. It cured at 170 degreeC over 8 hours, and then attached the rubber sheet which has a fiber layer to the grindstone. A grindstone plate fixed on a rubber sheet was cut into a checkerboard grid with a cutter to create an abrasive layer having a plurality of small pieces of grindstone blocks. In the same manner, a plurality of polishing layers were prepared.

In the rubber sheet used for the polishing layer, fibers are embedded to form a reinforcing layer. The fiber layer used what laminated | stacked the polyester fiber train of one direction in triple with 0.7 mm pitch inside. The angles of the fibers were + 75 °, 0 ° and -75 ° according to the example of Japanese Patent Laid-Open No. 2004-50400.

(Making order of grinding wheel for polishing)

The sponge material was attached to a phenol resin laminated tube having a pore diameter of 76.2 mm to provide a porous elastic layer. On the outer periphery of the sponge material, the polishing layer produced as described above was wound in a spiral shape and adhered to create a grinding wheel. Thereafter, the polishing layer was finished to complete a test grindstone having an outer diameter of 150 mm, a length of 610 mm, a hole diameter of 76.2 mm, and a grindstone height of 7 mm.

(Polishing test)

The workpiece was intentionally formed with irregularities to test the effect of eliminating the polishing nonuniformity. As shown in Fig. 6, tapes having a thickness of 200 µm and a dimension of 20 mm x 20 mm were placed at intervals of 30 mm in length and 30 mm in width on the back of the polishing surface of the workpiece. Attached.

The workpiece was polished using the test grindstone under the following conditions, and the polishing nonuniformity and the pressure response were observed.

                         Grinding condition Sharpener Outside diameter 150mm X length 610mm X hole diameter 76.2mm Workpiece Glass Substrate Epoxy Resin Copper Clad Laminate Thickness: 0.8t Dimension: 510 mm × 410 mm Polishing Machine Printed Board Grinding Machine Whetstone Speed 1800 rpm Speed of the workpiece 1.7 m / min Oscillation 470 cpm Pass count 1 pass Speed of the workpiece 2 m / min Polishing pressure 1.5A

As for the polishing nonuniformity, the polishing nonuniformity state of the workpiece | work after grinding | polishing was visually observed.

The pressure responsiveness calculated | required the weight of the removed workpiece | work after 100 passes with polishing pressure 1.5A, 2.0A, and 3.0A, and calculated | required the difference of the removal amount in each polishing pressure. The amount of removal is determined by measuring the weight before polishing and after polishing of each workpiece. This measurement was repeated with each workpiece, and the pressure responsiveness was computed from the removal weight in all 100 workpieces.

(Test result)

Porous Elastomer Properties Hardness 25% compression load (MPa) Resilience modulus (%) Example 1 14 0.044 60 Comparative Example 1 16 0.026 48 Comparative Example 2 22 0.044 45

Polishing test result    Polishing nonuniformity (visual observation)    Pressure responsiveness 1.5A 2.0A 2.5 A car evaluation Example 1 7 (good) 134.8 g 156.10 g 177.25 g 42.25 g Good Comparative Example 1 8 (light) 117.84 g 138.98 g 152.32 g 34.38 g Bad Comparative Example 2 9 (severe degree) 135.85 g 157.17 g 181.32 g 45.47 g Good

In Example 1, the grinding | polishing nonuniformity was not seen mostly, and the pressure response was also favorable. Relating to the characteristic value of the porous elastic body, the hardness of the rubber sponge material used is relatively low, but tends to have a relatively high 25% compressive load value and a high rebound modulus. It is thought that the characteristics of the rubber sponge material in such a tendency can improve the followability of the workpiece to the unevenness, and at the same time derive the desired grinding performance.

In the comparative example 1, the grinding | polishing nonuniformity of hardness is seen. The resin sponge used was relatively low in hardness, but also had a 25% compressive load value and a low resilience. In the characteristic of such a resin sponge, it turned out that the followability of the workpiece to the unevenness | corrugation is bad, and it is easy to produce grinding | polishing nonuniformity. Pressure response was the lowest. This is considered to be because the 25% compression load value is low.

In Comparative Example 2, a severe degree of polishing irregularity is observed. The resin sponge material has a relatively high hardness, a 25% compressive load value, and a low rebound modulus, which tends to be the opposite of the rubber sponge used in Example 1. Pressure response was equivalent to that of Example 1. This is considered to be because the 25% compression load value and the low rebound modulus were supplemented with strong hardness. But the grinding nonuniformity is so severe that it is surely lacking in harvestability.

Since the grinding wheel of the present invention uses a rubber sponge as the porous elastic body, it is possible to eliminate grinding irregularities and to improve grinding responsiveness. In general, the rubber sponge is relatively low in hardness compared with the conventional synthetic resin sponge material, but the resilience and the residual load are relatively high. The use of a porous elastic body having such a characteristic tendency eliminates grinding unevenness and at the same time significantly improves grinding response.

Claims (3)

A grinding wheel comprising a porous elastic body on a cylindrical core material and a polishing layer provided on an outer circumference of the porous elastic body, wherein the porous elastic body is a rubber sponge. The method of claim 1, The said grinding | polishing sponge is a grinding | polishing grinder characterized in that the rubber hardness is 5 to 40 on the rubber hardness meter C scale and the resilience modulus is 50 to 90%. The method according to claim 1 or 2, A grinding wheel for grinding said rubber sponge having a 25% compression load value of 0.010 to 0.200 MPa as defined in JISK6767.

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