JP2007281206A - Usage of sheet for suction-fixing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a using method of a sheet for suction-fixing that can prevent damage, contact trace, and breakdown of a suction-fixed member to be suctioned to the sheet for suction-fixing. <P>SOLUTION: This using method of the sheet for suction-fixing is employed when suction-fixing the member to be suction-fixed. The sheet is constituted with inclusion of at least a porous sheet. The using method is characterized in that the suction-fixed member is floated by blowing out gas through the sheet for suction-fixing on which the member to be suction-fixed is placed when the suction-fixed member is transferred. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for using a suction fixing sheet that is used for suction fixing of a member to be adsorbed and that includes at least ultra high molecular weight polyethylene.

  Conventional adsorption and fixing sheets are used for manufacturing liquid crystal panel glass substrates and semiconductor wafers (hereinafter referred to as glass substrates, etc.) used in personal computers and mobile phones. It is used for fixing.

  Examples of such a sheet for adsorption and fixation include a porous sheet. Further, as a porous sheet, a porous sheet made of ultra high molecular weight polyethylene (hereinafter referred to as “UHMWPE”) having an average molecular weight of 500,000 or more has been proposed in consideration of air permeability, rigidity, cushioning properties, and the like.

  A porous sheet made of UHMWPE is generally manufactured by filling a mold with UHMWPE and sintering. However, this method is a batch production and cannot be continuous or lengthened.

  For this reason, we have proposed a unique method of obtaining a long porous sheet by sintering the UHMWPE powder filled in the mold using heated steam and cutting it after cooling. (For example, refer to Patent Document 1 below).

  Since the porous sheet obtained by this method is long, it can be used for various purposes, and has a feature of high strength and excellent air permeability.

  However, a glass substrate or the like is easily damaged and has a structure in which scratches and contact marks are easily formed on the surface thereof. For this reason, for example, when a glass substrate or the like is sucked and fixed with a rubber sucker, the rubber sucker causes a contact mark on the surface of the glass substrate or the glass surface is damaged. .

JP-B-5-66855

  The present invention has been made in view of the above problems, and its purpose is to use a suction fixing sheet that can prevent a member to be sucked and fixed to the suction fixing sheet from being scratched or damaged or damaged. It is to provide a method.

  The inventors of the present application have studied a method for using the suction fixing sheet in order to solve the conventional problems. As a result, the inventors have found that the object can be achieved by adopting the following configuration, and have completed the present invention.

  That is, the method for using the suction fixing sheet according to the present invention is a method for using the suction fixing sheet that is used for sucking and fixing the member to be sucked and includes at least a porous sheet in order to solve the above-described problem. The porous sheet is configured to contain ultra-high molecular weight polyethylene, and when the adsorbed member is transported, gas is blown out through the adsorption fixing sheet on which the adsorbed member is placed, The adsorbed member is levitated.

  According to the above configuration, since the adsorption fixing sheet includes ultra high molecular weight polyethylene, the friction coefficient is low, and the wear resistance and impact resistance are excellent. Further, since the porous sheet has air permeability, when conveying the member to be adsorbed, it becomes possible to blow gas to the member to be adsorbed through the adsorption fixing sheet. As a result, the member to be sucked can be lifted from the suction fixing sheet and brought into a non-contact state, or the friction with respect to the suction fixing sheet can be reduced, thereby facilitating the transport of the member to be sucked. As a result, damage to the attracted member, and scratches / contact marks can be suppressed as much as possible.

  The porous sheet is preferably composed of a sintered body containing ultra high molecular weight polyethylene. Thereby, since the coefficient of friction of the porous sheet is further reduced, the attracted member can be transported more easily, and the wear resistance and impact resistance are improved, so that damage to the attracted member can be further prevented.

The present invention has the following effects by the means described above.
That is, according to the present invention, by blowing gas from the suction fixing sheet, the member to be sucked is lifted from the suction fixing sheet to be in a non-contact state, or friction with respect to the suction fixing sheet is reduced to be sucked. Since the member is transported, damage to the attracted member and scratches / contact marks can be suppressed as much as possible, and as a result, the yield of the product can be improved.

  One embodiment of the present invention will be described below. First, a method for using the suction fixing sheet according to the present embodiment will be described.

  The suction fixing sheet is disposed on a base having a vent hole, and a member to be sucked is placed on the suction fixing sheet. Next, the suction member is sucked and fixed to the suction fixing sheet by reducing the pressure through the vent hole of the base by an intake device or the like. After sucking and fixing, the member to be attracted is subjected to predetermined processing such as dicing.

  After the predetermined processing, the intake device is stopped, a gas such as air is supplied from the air supply device to the vent hole, and the compressed gas can be blown out from the adsorption fixing sheet. Thereby, the member to be sucked is floated from the suction fixing sheet to be in a non-contact state, or friction with respect to the suction fixing sheet is reduced. As a result, conveyance of the member to be attracted can be facilitated, and damage to the member to be attracted and scratches / contact marks can be suppressed as much as possible. The supply amount of the compressed gas is not particularly limited, and may be set as appropriate according to the weight of the member to be adsorbed.

  As the adsorbing and fixing sheet, a porous sheet including ultra high molecular weight polyethylene (hereinafter referred to as “UHMWPE”) is used. Examples of the porous sheet include a resin porous body made of UHMWPE or a sintered porous body. When the porous sheet is made of UHMWPE, the friction coefficient is low, the wear resistance and the sliding resistance are excellent, and the cost can be reduced. Ultra high molecular weight polyethylene which can be preferably used has a viscosity average molecular weight of 500,000 to 10,000,000, preferably 1,000,000 to 7,000,000. Ultra-high molecular weight polyethylene can be obtained from commercial products having trade names such as Hi-Z Million (Mitsui Petrochemical Industries) and Hostalen GUR (Tycona).

The porous compressive modulus of the sheet is preferably in the range of 100 to 1000 / cm ^2, and more preferably in a range of 200~400kg / cm ^2. Moreover, although the average hole diameter of a porous sheet can be appropriately set according to a use etc., it is preferable to exist in the range of 10-100 micrometers, and it is more preferable to exist in the range of 15-40 micrometers.

  Further, the thickness of the porous sheet can be appropriately set according to the use, etc., but is preferably in the range of 0.05 mm to 0.5 mm, and in the range of 0.1 mm to 0.3 mm. More preferably, it is within. If the thickness is less than 0.05 mm, the mechanical strength of the porous sheet may be reduced, and the porous sheet may be broken during use, and the workability when the porous sheet is attached to a lamination jig or the like may be reduced. On the other hand, if the thickness is larger than 0.5 mm, the air permeability of the porous sheet is lowered.

Breathable Frazier of the porous sheet is preferably in the range of 0.5~20cc ^/ cm 2 · sec, and more preferably in a range of 1~5cc ^/ cm 2 · sec. When the breathable fragile is less than 0.5 cc / cm ² · sec, the breathability is lowered, so that the tact time required for adsorbing and fixing the adsorbed member and floating is increased, and the productivity tends to be lowered. is there. On the other hand, if it exceeds 20 cc / cm ² · sec, the escape of air becomes too large, pressure cannot be applied to the member to be adsorbed, and it may be difficult to float the member to be adsorbed. In this case, it may be possible to increase the exhaust capacity, but this is not practical.

  As needle pushing hardness of a porous sheet, Shore D30-52 are preferred and 35-45 are more preferred.

  The coefficient of friction of the porous sheet is preferably 0.3 or less, and more preferably 0.18 or less. When the friction coefficient is within the above range, the friction with the attracted member can be reduced. When the friction coefficient exceeds 0.3, the life of the porous sheet tends to be shortened when used for sucking and fixing the attracted member.

As hardness (non-porous body) of UHMWPE itself, Shore D hardness is preferably 50 to 60, and more preferably 52 to 57. Moreover, it is preferable that the compression elastic modulus exists in the range of 200-400 kg / cm < ² >. The average pore diameter is preferably in the range of 15 to 40 μm. The breathable fragile is preferably in the range of 1 to 5 cc / cm ² · sec.

  The adsorption fixing sheet according to the present invention may be subjected to antistatic treatment. By performing the antistatic treatment, for example, it is possible to avoid sparks due to charging of the suction fixing sheet in the dicing process of the semiconductor wafer, and to prevent damage to the wafer due to sparks. Moreover, it is possible to prevent dust and dirt from adhering to a workpiece such as a semiconductor wafer.

  The adsorption-fixing sheet according to the present invention may be a porous sheet alone or a laminate in which a plurality of other porous sheets having different pore diameters, strengths, air permeability, and the like are stacked. In this case, the other porous sheet is laminated on the surface opposite to the adsorption surface of the porous sheet. When another porous sheet is laminated on the suction fixing sheet, sufficient mechanical strength can be imparted for suction fixing conveyance.

  Further, the adsorption fixing sheet according to the present invention may be colored. For example, the UHMWPE porous sheet is white and opaque, but when it is colored in an arbitrary color, there are the following advantages. That is, when the UHMWPE porous sheet is used for cutting the glass plate for liquid crystal, a scribing mark (a fine white line) is attached to the glass plate in the scribing process, but if the porous sheet is white, It is difficult to distinguish between the porous sheet and the scribe mark by image recognition, and processing control in subsequent cutting processing may become impossible. However, if the UHMWPE porous sheet is colored in an arbitrary color other than white, the image of the scribe mark can be easily recognized by the contrast between the white color of the scribe mark and the color of the porous sheet, and cutting can be performed with high accuracy. It becomes like this.

  The sheet for adsorbing and fixing according to the present invention can be produced by various conventionally known methods. For example, in the case of a sintered porous sheet of UHMWPE, the method described in Japanese Patent No. 2020026 can be applied. More specifically, for example, UHMWPE powder (particle size is usually 30 to 200 μm) is filled in a mold, and then this is sintered in a steam atmosphere heated above the melting point of UHMWPE to form a block-like porous material Let it be the body. In this way, UHMWPE powder is filled in a mold and sintered in a heated steam atmosphere, and therefore, a mold having at least one opening (for heating steam introduction) is used. The time required for sintering varies depending on the amount of powder filling, the temperature of water vapor, and the like, but is usually about 1 to 12 hours.

  Since the water vapor used at this time is heated to a temperature equal to or higher than the melting point of UHMWPE, it is in a pressurized state, so that it can easily enter between the UHMWPE powders filled in the mold. In order to facilitate the entry of heated water vapor between the UHMWPE powders, the powder was filled in a mold, the mold was placed in a pressure vessel, subjected to a degassing operation to reduce the pressure, and then heated. You may make it sinter in water vapor | steam atmosphere. The degree of decompression at this time is not particularly limited, but is preferably about 0.13 to 13 kPa.

  Therefore, the sintering of the UHMWPE powder filled in the mold is performed by providing a steam inlet pipe and its open / close valve in the pressure vessel, degassing the air between the powders, and stopping the decompression or continuing the decompression. The method can be carried out by opening a steam valve and introducing heated steam.

  During this sintering, the UHMWPE powder is heated to a temperature above its melting point, but its melt viscosity is high, so it does not flow very much, and the powder shape is partially or largely maintained, and adjacent powders are in contact with each other. Thus, heat-sealing is performed to form a block-shaped porous body (non-contact portions between the powders become pores of the porous molded body). In addition, although it can also pressurize if desired in the case of sintering, it is preferable that the pressure shall be about 1 Mpa or less normally.

  After performing the sintering as described above, it is cooled. In cooling, it is preferable to avoid rapid cooling in order to prevent the occurrence of cracks in the block-like porous body. As a cooling method, for example, a method of leaving it at room temperature can be employed. The cooling may be performed while the block-shaped porous body is placed in a mold, or may be performed by removing it from the mold. After cooling the block-shaped porous body, the block-shaped porous body is cut into a sheet shape having a predetermined thickness using a lathe and the like, and the sheet is punched into a predetermined shape or cut into a predetermined shape. You can also

  Since the method performs only sintering in a state where no particulate raw material with few impurities is added, a clean raw sheet can be obtained. These sheets have been found to be almost free of impurities.

  The compression elastic modulus and average pore diameter of the sintered porous body can be controlled by the particle diameter of the UHMWPE powder. In order to obtain the compression modulus and average pore diameter, the particle diameter of the UHMWPE powder is preferably in the range of 30 to 170 μm, and more preferably in the range of 100 to 170 μm.

  Hereinafter, preferred embodiments of the present invention will be described in detail by way of example. However, the materials, blending amounts, and the like described in the examples are not intended to limit the scope of the present invention only to them, but are merely illustrative examples, unless otherwise specified.

Example 1
First, a porous sheet made of ultra high molecular weight polyethylene (manufactured by Nitto Denko Corporation, trade name: Sunmap, thickness 0.2 mmt) was fixed to the lower metal sucker with a breathable adhesive material. Further, a glass plate having a thickness of 0.5 mmt was placed on the porous sheet, and this glass plate was fixed by suction and cut into a predetermined size. The glass plate after cutting had a thickness of 0.5 mm, a short side of 100 mm, a long side of 200 mm, and a weight of 25 g.

  Next, air was made to flow backward, air was sprayed on the glass plate through the porous sheet, and this glass plate was floated from the porous sheet. When the air pressure when the porous sheet floated was measured, it was about 0.2 MPa. Further, the end face of the glass plate was lightly touched in the state of being floated, and the glass plate was conveyed to the next process. When the surface state of the glass plate was confirmed after conveyance, no traces such as scratches or damage were found.

(Example 2)
In this example, the glass plate was cut and conveyed to the next step in the same manner as in Example 1 except that a porous sheet having a thickness of 0.3 mm was used. The air pressure when the porous sheet floated was about 0.2 MPa. Furthermore, when the surface state of the glass plate after conveyance was confirmed, traces, such as a damage | wound and damage, were not seen.

(Example 3)
In this example, the glass plate was cut and conveyed to the next step in the same manner as in Example 1 except that a porous sheet having a thickness of 0.5 mm was used. The air pressure when the porous sheet floated was about 0.2 MPa. Furthermore, when the surface state of the glass plate after conveyance was confirmed, traces, such as a damage | wound and damage, were not seen.

(Comparative Example 1)
In this comparative example, the glass plate was sucked and fixed on the porous sheet in the same manner as in Example 1, and then cut into a predetermined size. Next, four places of the glass plate were sucked from the upper side using a urethane rubber sucker (trade name; manufactured by Moritec Co., Ltd.), and the glass plate was separated from the porous sheet. Thereby, the glass plate was conveyed to the following process. When the surface state of the glass plate was confirmed after the conveyance in the same manner as in Example 1, the traces of the suction cups by the urethane rubber sucker remained on the surface of the glass plate.

(Reference Example 1)
In this reference example, the glass plate was cut and transported to the next step in the same manner as in Example 1 except that a porous sheet having a thickness of 0.1 mmt was used. Furthermore, when the surface state of the glass plate after conveyance was confirmed, traces, such as a damage | wound and damage, were not seen. However, the air pressure when the porous sheet floated was a value exceeding 0.2 MPa, and the conveyance efficiency was slightly reduced as compared with Example 1.

(Reference Example 2)
In this reference example, the glass sheet was cut and conveyed to the next step in the same manner as in Example 1 except that a porous sheet having a thickness of 1.0 mmt was used. Furthermore, when the surface state of the glass plate after conveyance was confirmed, traces, such as a damage | wound and damage, were not seen. However, the air pressure when the porous sheet floated was a value exceeding 0.2 MPa, and the conveyance efficiency was slightly reduced as compared with Example 1.

(Breathability)
The air permeability of the adsorption and fixing sheets according to Examples and Comparative Examples was measured as follows based on JIS L 1096. That is, the measurement was performed using a fragile tester, and each measured value was a value in the thickness direction of the entire adsorption fixing sheet. The measurement pressure was 0.123 kPa. The results are shown in Table 1 below.

(result)
As is clear from Table 1, in Examples 1 to 3, it was possible to easily carry the air with an air pressure of about 0.2 MPa, and there was no trace of scratches or breakage on the glass plate. On the other hand, in Comparative Example 1, traces due to the urethane rubber sucker remained on the surface of the glass plate. In addition, as shown in Reference Example 1, when the breathable fragile exceeds 20 cc / cm ² · sec, the glass plate is levitated from the region where the glass plate is not placed on the surface of the adsorption fixing sheet. For this reason, a part of the air leaked, so that air pressure exceeding 0.2 MPa was required for conveying the glass plate. In addition, as shown in Reference Example 2, when the breathable fragile is less than 0.5 cc / cm ² · sec, it is difficult for air to pass through the adsorption fixing sheet. Similar to the above, an air pressure exceeding 0.2 MPa was required.

Claims (2)

A method for using a suction fixing sheet that is used for suction fixing of a member to be adsorbed and includes at least a porous sheet,
The porous sheet comprises ultra high molecular weight polyethylene,
A method of using a suction fixing sheet, wherein, when the member to be sucked is conveyed, gas is blown out through the suction fixing sheet on which the member to be sucked is placed to float the member to be sucked. .   The said porous sheet is comprised from the sintered compact containing ultra high molecular weight polyethylene, The usage method of the sheet | seat for adsorption fixation of Claim 1 characterized by the above-mentioned.