JPH08252869A - Adsorbing and fixing sheet and adsorbing and fixing method by using the same sheet - Google Patents

Abstract

PURPOSE: To prevent contamination due to adhesive of a material to be processed and to easily position the workpiece by recessing the predetermined part of an air permeable sheet used to adsorb and fix. CONSTITUTION: The air permeable sheet 6 of an adsorbing and fixing sheet is recessed 7 at a predetermined part to arbitrary number. The recess 7 is formed, for example, by heating and pressurizing the predetermined part of the one side of the sheet 6 by a die or laminating a sheet having a through hole on the one side of the sheet 6. A method for adsorbing and fixing a workpiece 4 by using the adsorbing and fixing sheet comprises the steps of so disposing the adsorbing and fixing sheet in which the predetermined part of the sheet 6 is recessed 7 on a base 3 that the recess 7 forming surface becomes upside, mounting the workpiece 4 in the recess 7 of the adsorbing and fixing sheet, then operating a vacuum pump connected to a suction hole 2 to pressure reduce via a vent hole 2, and adsorbing to fix the workpiece 4 to the recess 7 of the adsorbing and fixing sheet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet used for adsorption and fixation, and an adsorption fixing method using the sheet.

[0002]

2. Description of the Related Art Precision cutting of glass plates for liquid crystals, semiconductor wafers, ceramic capacitors and ceramic substrates, precision coating on glass plates for semiconductors and semiconductor wafers, precision bonding of polarizing plates and retardation plates or these and glass plates At the time of processing such as alignment, these work pieces are fixed so as not to be displaced.

A suction fixing method is used to fix the work piece. This method is, for example, as shown in FIG.
A base (made of a material having mechanical strength such as metal) 3 having a predetermined number of ventilation holes 1 on its upper surface and suction holes 2 at predetermined positions is used. The workpiece 4 is placed, and the inside of the base 3 is depressurized by a vacuum pump (not shown) connected to the suction hole 2, so that the workpiece 4 is sucked and fixed onto the base 3. The position shift is prevented and this is processed.

[0004] Usually, at the time of adsorption and fixation, an adhesive tape 5 having an adhesive layer (not shown) formed on the entire surface of one side of a base material made of a plastic film is used, and a work piece is placed on the adhesive layer of the adhesive tape 5. 4 (“Semiconductor industry and advanced technology”, pages 120 to 127, issue date October 25, 1987, published by Kogaku Tosho Co., Ltd.). This adhesive tape is used to prevent the inadvertent movement of the object to be processed after the object is sucked and fixed to be processed and then removed from the base.

[0005]

However, in the method of using an adhesive tape having an adhesive layer provided on the entire surface of one side of a substrate, the adhesive migrates to the surface of the work piece and contaminates the work piece. There's a problem. Therefore, it is an object of the present invention to provide a suction fixing sheet which does not contaminate a work piece with an adhesive, and a novel suction fixing method using the sheet.

[0006]

As a result of earnest research for solving the above problems of the prior art, the present inventor has found that the intended purpose can be achieved by using a breathable sheet, and completes the present invention. It came to.

That is, the adsorption fixing sheet according to the present invention is characterized in that a predetermined portion of the breathable sheet is a recess.

The material of the adsorption fixing sheet according to the present invention is not particularly limited and includes, for example, polyethylene, ultra high molecular weight polyethylene (hereinafter referred to as "UHMWPE"), polypropylene, polystyrene, polyamide, polyester, polyacryl, fluororesin ( Materials made of polymer materials such as polytetrafluoroethylene) can be used.

In the present invention, a woven fabric, a non-woven fabric or a porous sheet made of these polymer materials is used as a breathable sheet (thickness is usually 0.05 to 10 mm). The air permeability of the breathable sheet can be represented by, for example, a Gurley value, and in the present invention, it is usually about 20.
Those having a time of 00 seconds / 100 cm ³ or less are used. In addition,
The Gurley value can be measured according to JIS P8117.

In the present invention, the predetermined portion of the breathable sheet is
It is important that the recess is formed. FIG. 1 relates to the present invention.
Shows an example of a sheet for adsorption and fixation, where 6 is a breathable sheet.
And the predetermined portion is the recess 7 (in the illustrated example, there are two
However, the number of these recesses can be set arbitrarily).
It The depth dimension of the recess is not particularly limited, but usually,
It is about 50 to 500 μm. And this recess is, for example,
For example, one side of the breathable sheet should be heated and pressed with a mold
It can be formed by a concave method. Working conditions at this time
Is usually (M-10) ° C to (M + 10) ° C, pressure
Power is 1kg / cm ²The heating and pressing time is 1 minute or less.
It The M ° is the polymer that constitutes the breathable sheet.
The melting point of the material.

The breathable sheet may be antistatic-treated. By applying antistatic treatment,
For example, in the dicing process of a semiconductor wafer, it is possible to avoid sparks due to electrification of the air permeable sheet and prevent damage to the wafers due to the sparks. Further, it is possible to prevent dust and dirt from adhering to a workpiece such as a semiconductor wafer.

The antistatic treatment of the breathable sheet does not have to be special, and a usual method can be adopted. For example, a method for producing a breathable sheet by mixing an antistatic agent with a polymer material, or contacting the breathable sheet with an antistatic agent-containing liquid (immersion,
It is possible to employ a method in which the sheet is impregnated with an antistatic agent by coating or the like.

The suction-fixing sheet according to the present invention may have a recess formed by laminating a sheet having a through hole on one surface of a breathable sheet. FIG. 2 shows an example of this suction-fixing sheet, in which a sheet 8 having a predetermined number of through holes is laminated on one side of a breathable sheet 6. The breathable sheet 6 and the sheet 8 can be laminated by a method of adhering both with an adhesive, a method of adhering with a double-sided adhesive tape, or the like. The adsorption fixing sheet obtained by this lamination has a structure in which the recess 7 is formed by the through hole of the sheet 8. The sheet 8 (this sheet is not breathable, that is, a “non-breathable sheet”) is a sheet made of the same polymeric material as the breathable sheet 6 and provided with a predetermined number of through holes. . The suction-fixing sheet shown in FIG. 2 can also be subjected to antistatic treatment on the breathable sheet 6 as in the case of FIG. Of course, the sheet 8 may be subjected to antistatic treatment.

As described above, in the present invention, the material of the breathable sheet is not limited, but in view of the fact that the breathability and the thickness can be set relatively freely, the breathable sheet is made of U.
It is preferable to use a porous sheet made of HMWPE. U
HMWPE is peculiar in that it has a high molecular weight (measured by a viscosity method) of about 100,000 or less, whereas it has a high value of about 500,000 or more. Such UHMW
PE is, for example, "Hi-Zex Million" from Mitsui Petrochemical Co., Ltd. and "Hostalen GUR" from Hoechst.
It is marketed under the trade name such as.

Since this UHMWPE has a high melt viscosity and does not easily flow even when heated above the melting point, a method different from other polymer materials is adopted when manufacturing a porous sheet. Here, an example of a method for producing the UHMWPE porous sheet will be described. The porous sheet is obtained by, for example, filling a mold with UHMWPE powder, then sintering this in a steam atmosphere heated to a temperature equal to or higher than the melting point of UHMWPE to form a block-shaped molded body, and then cooling it. It can be manufactured by a method of cutting a molded body into a sheet having a predetermined thickness.

In this method, first, UHMWPE
Fill the mold with powder (usually 30-200 μm particle size),
Then, this is sintered in a steam atmosphere heated to a melting point of UHMWPE or higher to obtain a block-shaped molded body. Since the UHMWPE powder is filled in the mold in this way and is sintered in a heated steam atmosphere, a mold having at least one opening (for introducing heated steam) is used. The time required for sintering varies depending on the powder filling amount, the temperature of steam, and the like, but is usually about 1 to 12 hours.

Since the water vapor used at this time is heated to a temperature higher than the melting point of UHMWPE and is in a pressurized state, it can easily enter between the UHMWPE powders filled in the mold. In order to make it easier for the heated steam to enter between the UHMWPE powders, the powders were filled in a mold, the molds were placed in a pressure resistant container, and deaeration operation was performed to reduce the pressure, and then the powders were heated. You may make it sinter in a steam atmosphere. The degree of pressure reduction at this time is not particularly limited, but is preferably about 1 to 100 mmHg.

Therefore, for the sintering of the UHMWPE powder filled in the mold, a steam inlet tube and its on-off valve are provided in the pressure vessel, and after degassing the air between the powders,
It can be carried out by a method of opening the steam valve and introducing heated steam while stopping or continuing the depressurization.

During this sintering, the UHMWPE powder is heated to a temperature equal to or higher than its melting point, but its melt viscosity is high, so that it does not flow so much, its powder shape is maintained partially or largely, and the adjacent powders have the same shape. At the contact portion, heat fusion is performed to form a porous block-shaped molded body (the non-contact portions of the powders become fine pores of the porous molded body). During sintering, pressure may be applied if desired, but the pressure is usually preferably about 10 kg / cm ² or less.

After sintering is performed as described above, it is cooled. When cooling, it is preferable to avoid rapid cooling in order to prevent cracks from occurring in the block-shaped molded body, and for example, a method of cooling by leaving it at room temperature can be adopted. The cooling may be performed while the block-shaped molded body is kept in the mold, or may be taken out from the mold. After cooling the block-shaped molded body in this manner, the porous sheet can be obtained by cutting to a predetermined thickness with a lathe or the like.

The pore size and porosity of the UHMWTE porous sheet obtained by the above method are determined by the particle size of the UHMWPE powder used and the presence or absence of pressure during sintering. If the other conditions are the same, the larger the particle size of the powder used, the larger the pore size of the fine pores and the higher the porosity of the porous sheet. Further, when pressure is not applied during sintering, the pore size of the micropores is larger than that when pressure is applied, and a porous sheet having a high porosity can be obtained. Further, when pressure is applied during sintering, the higher the pressure, the smaller the pore size of the fine pores, and the porous sheet with low porosity can be obtained.

In the present invention, polytetrafluoroethylene (hereinafter referred to as "PTFE") is used as the breathable sheet.
It is also preferable to use a porous sheet having a property. The PTFE porous sheet is excellent in liquid repellency, and the adsorption fixing sheet using the PTFE porous sheet has excellent liquid repellency even when a treatment liquid such as water is used when adsorbing and fixing a workpiece and processing the same. Therefore, there is an advantage that the treatment liquid can be prevented from entering the exhaust system.

Here, a method of adsorbing and fixing a work piece using the above-mentioned adsorption and fixation sheet will be described. In this suction-fixing method, a suction-fixing sheet having a recess is arranged on a base having a ventilation hole so that the recess-forming surface faces upward, and the workpiece is placed in the recess of the suction-fixing sheet. Then, the workpiece is sucked and fixed in the concave portion by reducing the pressure through the ventilation holes of the base.

FIG. 3 shows an example of the adsorption fixing method according to the present invention. In FIG. 3, 3 is a base, and FIG.
Similarly to the one shown in FIG. 3, it has a predetermined number of ventilation holes 1 and suction holes 2. A suction fixing sheet (suction fixing sheet in FIG. 1) having a predetermined portion of the breathable sheet 6 as a concave portion 7 is arranged on the base 3 so that the concave portion forming surface is on the upper side. The workpiece 4 is placed in the recess of the sheet. Next, by operating a vacuum pump (not shown) connected to the suction hole 2, the pressure is reduced through the ventilation hole 2 and the workpiece 4
Is fixed to the concave portion 7 of the suction fixing sheet by suction, and a predetermined process such as a dicing process is performed.

In this method, since the concave portion of the suction-fixing sheet is used as the mounting portion for the work piece, the work piece can be easily positioned. In order to make this positioning easier, the concave portion of the suction fixing sheet may be colored. Further, even if the object to be processed is subjected to a dicing process or the like, there is an advantage that the chip obtained by the process does not stop in the concave portion and move carelessly.

The adsorption fixing sheet shown in FIG. 2 can also be used in the adsorption fixing method according to the present invention. Also in this case, the suction-fixing sheet having the concave portions is placed on the base having the ventilation holes so that the concave portion forming surface is on the upper side (the sheet 8 is on the upper side and the breathable sheet 6 is on the lower side). The workpiece is placed in the recess formed by the through hole of the sheet, then the pressure is reduced through the ventilation hole of the base, the workpiece is adsorbed and fixed in the recess, and predetermined processing such as dicing is performed. is there.

[0027]

The present invention will be described in more detail with reference to the following examples.

Example 1 UHMWPE powder (molecular weight: 6 million, melting point: 135 ° C., average particle size: 110 μm) was filled in a cylindrical mold having an inner diameter of 105 mm (top opening, bottom closing), and the powder was 90 g / cm ^2.
Pressurize at a rate of.

This is placed in a metal pressure vessel (equipped with a steam inlet tube and its opening / closing valve), and the vacuum pump is operated to reduce the atmospheric pressure to 30 mmHg, thereby deaerating the air between the filled powders. .

After deaeration, the vacuum pump was stopped, the steam introduction valve was opened, steam (temperature 158 ° C., 6 atm) was introduced, and the mixture was heated for 60 minutes to sinter the UHMWPE powder and obtain a round rod-shaped porous body. .

Next, this was left to cool in a room at a temperature of 25 ° C. for 3 hours and then cooled from the mold to a round bar-shaped body (outer diameter of about 105).
mm) is taken out and cut along the circumferential direction to a thickness of 500 μm by a lathe, and a long white opaque porous sheet (porosity 25%, average pore diameter 30 μm, Gurley value 4 seconds /
100 cm ³ ) is obtained.

This porous sheet has a length of 10 and a width of 10
Cut to cm. Next, heat and pressure (temperature 140 ° C, pressure 0.5 kg / cm) from one side using a mold.
² , heating and pressurizing time 1 minute), vertical and horizontal are 4 cm each,
A suction fixing sheet was obtained by forming four recesses having a depth of 0.2 mm.

Example 2 Except that 97.5 parts by weight of the same UHMWPE powder as used in Example 1 was mixed with 1.5 parts by weight of an antistatic agent (Electrostripper TS-3, manufactured by Kao Corporation). Is a long white opaque porous sheet (thickness 200 μm, porosity 25%, average pore size 3).
0 μm, Gurley value of 5 seconds / 100 cm ³ ) was obtained, and this was punched into a disc shape with a diameter of 20 cm.

On the other hand, separately from this, polyethylene terephthalate having a thickness of 200 μm and a diameter of 20 cm (hereinafter referred to as “PE
A sheet (referred to as "T") is prepared, and punched out to form a circular hole having a diameter of 15.3 cm to form a ring.

Then, a ring-shaped PET sheet is bonded to one side of the disk-shaped UHMWPE porous sheet with an adhesive to form one circular recess (diameter 15.3c).
m, a depth of 200 μm) was obtained.

Comparative Example A polyethylene film having a thickness of 50 μm has a thickness of 10 on one side.
An adhesive tape provided with a 0 μm thermosetting acrylic adhesive layer was obtained.

Test Example 1 The adsorption and fixation sheets obtained in Example 1 and Comparative Example are placed on a metal base having the same structure as shown in FIG. At this time, the suction-fixing sheet of Example 1 is arranged so that the concave portion is on the upper side, and the suction-fixing sheet (adhesive tape) of the comparative example is arranged so that the adhesive layer is on the upper side.

Then, a ceramic capacitor (thickness 150 μm, length 38 mm, width 3
8 mm) (in the concave portion in Example 1 and on the adhesive layer in Comparative Example), and then the vacuum pump connected to the suction hole is operated to reduce the pressure through the ventilation hole. After being fixed by suction, the ceramic capacitor is diced into a size of 2 mm in length and 2 mm in width. After processing, the reduced pressure was stopped and the diced ceramic capacitor was removed from the adsorption fixing sheet. Regarding the adhesive tape of Comparative Example, after dicing, the adhesive was thermoset by heating at a temperature of 80 ° C. for 1 minute, and then the dicing-processed ceramic capacitor was removed.

The adsorption fixing sheet of Example 1 could easily mount the ceramic capacitor in the recess. In addition, the dicing-processed ceramic capacitor did not move carelessly, and it was easy to remove from the adsorption fixing sheet.

On the other hand, in the comparative example, since the dicing-processed ceramic capacitor is firmly adhered to the adhesive layer, the peeling work is difficult, and 0.5% of the processed ceramic capacitor has an adhesive migration phenomenon. Was observed.

Test Example 2 The adsorption fixing sheet of Example 2 was placed on the metal base having the same structure as shown in FIG. 1 so that the UHMWPE porous sheet was on the base side, and the through holes of the PET sheet were used. A silicone wafer (disc-shaped with a diameter of 15 cm) is placed in the recess formed by.

Then, while flowing water from the silicone wafer side, the vacuum pump connected to the suction hole is operated to reduce the pressure through the ventilation hole so that the silicone wafer is adsorbed and fixed to a size of 20 mm in length and 25 mm in width. Dicing process. After the processing, the water was stopped and the reduced pressure was stopped, and the chips obtained by dicing were removed from the adsorption fixing sheet. The glass plate can be easily removed from the suction-fixing sheet.In this case as well, the silicone wafer can be easily placed in the recess of the suction-fixing sheet, and the chips obtained by dicing can be moved carelessly. There was nothing. Moreover, it was easy to remove it from the adsorption fixing sheet. Furthermore, no water entered the exhaust system.

[0043]

Since the present invention is constructed as described above and uses the breathable sheet, the work piece is not contaminated by the adhesive. Further, since the air-permeable sheet is formed with the concave portion, it is possible to easily position the workpiece when adsorbing and fixing.

[Brief description of drawings]

FIG. 1 is a front view showing an actual example of a suction-fixing sheet according to the present invention.

FIG. 2 is a front view showing another example of the adsorption fixing sheet according to the present invention.

FIG. 3 is a front view showing an actual example of a suction fixing method according to the present invention.

FIG. 4 is a front view showing an example of a conventional suction fixing method.

[Explanation of symbols]

 1 Vent hole 2 Suction hole 3 Base 4 Workpiece 6 Breathable sheet 7 Recess

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Toshimitsu Tachibana 1-2-1, Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation

Claims (3)

[Claims] 1. A suction-fixing sheet, characterized in that a predetermined portion of the breathable sheet is a recess. 2. An adsorbing / fixing sheet having a recess formed by laminating a sheet having a through hole on one surface of a breathable sheet. 3. A suction-fixing sheet having a recess is arranged on a base having ventilation holes so that the recess-forming surface faces upward, and a workpiece is placed in the recess of the suction-fixing sheet. Then, a method of adsorbing and fixing the object to be processed in the concave portion of the sheet by reducing the pressure through the ventilation holes of the base.