JP2000246787A - Manufacture of thermoplastic polymer sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use a spacer held at an accurate gap with excellent thickness accuracy and small sheet warp by cooling a thermoplastic polymer sheet melt extruded from a T-die or a coating hanger die by a metal belt having a length so that a contact time at a non-curvature part becomes specific in a flowing direction. SOLUTION: An air gap distance until a thermoplastic polymer sheet is brought into contact with a metal belt after the sheet is extruded from a T-die or a coating hanger die having a lip gap of predetermined times as large as a thickness of the sheet is set to a predetermined length. When the gap exceeds a predetermined value, a thickness accuracy is deteriorated, and hence to fall the gap within a predetermined value, a diameter of a roll is reduced, and a lip end of the die is formed in a shape along the roll. A length of the belt is set so as to sufficiently cool the sheet by bringing a cooling time at a position having no curvature to the flowing direction of the sheet into 20 s or above. Thus, a spacer for holding the accurate gap becomes optimum with excellent thickness accuracy and small sheet warp.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a thermoplastic polymer sheet, which is excellent in thickness accuracy, has less warpage of the sheet, and has less weight loss due to abrasion. It is suitable for applications such as spacers that require thickness accuracy, and is used, for example, in the fields of polishing spacers, high-precision motor-unit sliding spacers, and printer heads. The polishing spacer can be used for polishing a Si wafer, polishing a glass for a display device, polishing a hard disk made of aluminum or the like.

[0002]

2. Description of the Related Art Conventionally, when a thermoplastic polymer sheet is manufactured by a melt extrusion method, the thickness accuracy is poor and curling occurs, so that it is unreliable as a spacer application for maintaining a highly accurate gap. Met. For example, when a polishing spacer of a Si wafer is considered as a polishing spacer, abrasion resistance is required, but none is satisfied, and there is a problem such as dust generation.

As a spacer for maintaining a high-precision gap, a metal such as aluminum or copper may be used. In particular, as a polishing spacer for a Si wafer for a semiconductor, a metal spacer is used as in the case of a Si wafer. Is polished, and the metal powder becomes a contaminant at the time of forming a pattern circuit in a later process, and causes a short circuit between the circuits.

In the polymer sheet, the thickness accuracy is difficult, and the curl characteristic is a problem, so that it cannot be used as a spacer for maintaining a highly accurate gap. An epoxy resin containing a glass filler is a tough resin, but contains a glass filler. Therefore, it is necessary to pay attention to using the filler because it tends to generate a filler powder that becomes a contamination. There is a need for a spacer that maintains a high-precision gap and does not generate contamination that may cause a defect in a subsequent process.

[0005] In general, when a melt extrusion method using a T die or a coat hanger die is used as a means for improving the thickness accuracy, a die exit due to shear stress or stagnation in a flow path through which a thermoplastic polymer passes. Method to reduce the pressure variation in the die, to improve the accuracy of the die surface and lip that causes uneven lines called die line, and to improve the temperature distribution in the width direction and thickness direction of the sheet extruded from the die In order to reduce the neck-in, a method of blowing hot air or providing a guide roll may be used, but it has not been solved yet.

As a means for producing a polymer sheet having good thickness accuracy, a solvent casting method in which a thermoplastic polymer is dissolved in a solvent, coated on a film or a metal belt and dried is known. When the thickness of the sheet is increased, the productivity and the residual solvent in the sheet become problems.

The injection molding method in which a thermoplastic polymer is sealed in a mold whose dimensions have been finished with high precision is considered to be a promising candidate because there is no problem in productivity as is known in the molding of CD disks. In the injection molding method, a sheet having a thickness on the order of several mm is the limit, and it cannot cope with a thickness on the order of several hundred μm.

[0008] It is also known to perform post-processing to improve curl properties, but it is a plate whose surface is finished with high precision.
The method of pressing the sheet at a certain interval, improving the thickness accuracy, and improving the curl has poor productivity, is not suitable for mass production, and is not suitable as a manufacturing method. Regarding the sheet warpage, the generally known cooling method using a cooling roll is considered to cause the sheet to be warped by shaping the circumference of the cooling roll during cooling and solidification. It is conceivable to use a very large chill roll to increase the curvature, but this is not economically suitable.

It is considered that a solution can be found by cooling and solidifying the polymer sheet on a flat plate having no curvature. However, the surface temperature of the polymer sheet in contact with the cooling surface and the temperature on the opposite side of the polymer sheet are considered. Warpage of the sheet is likely to occur due to the difference from the surface temperature. As described above, it has been difficult in the state of the art to produce a thermoplastic polymer sheet having excellent thickness accuracy, small sheet warpage, and high abrasion resistance.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polymer sheet which is excellent in thickness accuracy, has a small warpage of the polymer sheet, and is used as a spacer for maintaining a high-precision gap. Another object of the present invention is to provide a method for producing a thermoplastic polymer sheet which can be used as a polishing sheet without any problem.

[0011]

According to the prior art, the thickness accuracy that could not be attained is excellent, the sheet warpage is small,
In addition, as a result of diligent studies to obtain a polymer sheet having a small weight loss due to taper abrasion, the thermoplastic polymer sheet melt-extruded from a T-die or a coat hanger ladder is used as the thermoplastic polymer sheet extruded from the die. The time of contact without curvature in the flow direction of
This is a method for producing a thermoplastic polymer sheet which is formed into a cooling sheet using a metal belt having a length of 0 second or longer.

In a further preferred embodiment, the temperature (V1) of the first portion of the metal belt where the thermoplastic polymer sheet comes into contact with the metal belt is adjusted to the melting point (T.sub.T) of the thermoplastic polymer.
g), the temperature (V2) of the metal belt which is in the range of Tg-10 ≦ V1 ≦ Tg + 150 (° C.) and has no curvature in the flow direction of the thermoplastic polymer sheet is Tg-30.
≦ V2 ≦ Tg + 50 (° C.), and the temperature (V3) of the metal belt at the portion where the cooled thermoplastic polymer sheet is separated from the metal belt is Tg−50 ≦ V3 ≦ T
g (° C.) and in the range of V 3 ≦ V 2 ≦ V 1 (° C.), and the surface temperature of the thermoplastic polymer sheet in contact with the metal belt and the surface temperature of the opposite side of the polymer sheet This is a method for producing a thermoplastic polymer sheet having the same surface temperature.

Further, the lip gap of the T die or the coat hanger die is not less than 3 times and not more than 50 times the thickness of the thermoplastic polymer sheet, and the thermoplastic polymer sheet is extruded from the lip of the die. The distance before contact with the metal belt is 10 mm or more and 100 mm or less, and the thermoplastic polymer sheet melt-extruded with the T die or the coat hanger die is a crystalline resin and has a thickness of 300 μm. 1000 μm or less, and the thickness tolerance (Rmax) within the polymer sheet plane is 1
0 μm or less, and the amount of warpage of a 300 mm square sheet is 5
mm or less, and the weight loss due to taper wear is 10 mg
/ 1000 revolutions, and wherein the thermoplastic polymer sheet is a polyetheretherketone.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The thickness of a thermoplastic polymer sheet is not less than 300 μm and not more than 1000 μm.
m or less, more preferably 400 μm or more and 70 μm or more.
0 μm or less. When the thickness of the polymer sheet is less than 300 μm, a sheet satisfying the thickness accuracy and curl properties can be obtained by a usual melt extrusion method, and there is no need to limit the production method. If it exceeds 1000 μm, it is not preferable in terms of function.

In-plane thickness tolerance (Rmax) of the polymer sheet
Is preferably 10 μm or less, more preferably 5 μm
It is as follows. In-plane thickness tolerance of polymer sheet (Rma
If x) exceeds 10 μm, for example, when polishing a Si wafer, it is polished to the same level as the thickness tolerance of the polymer sheet, so that it is preferably 10 μm or less.

The warp of the polymer sheet is preferably 300 mm square, preferably 5 mm or less, more preferably 3 mm or less, more preferably 1 mm or less. If the warpage of the polymer sheet exceeds 5 mm, even if the thickness accuracy is good, it is difficult to maintain a high-precision gap due to the stress, and handling becomes difficult and productivity is deteriorated.

Weight loss due to taper wear is 10 mg /
It is preferably 1,000 times or less, more preferably 5 mg /
1000 times. When used as a spacer for polishing, contamination of the spacer material by polishing deteriorates the polishing accuracy and the degree of polishing finish, and further acts as a contaminant at the time of processing in a later step, thereby deteriorating productivity. If it exceeds 10 mg / 1000 times, for example, in the case of polishing a Si wafer for a semiconductor, when forming a precise circuit pattern in a post-process, if there is contamination, the defective rate will increase drastically. Can also cause short circuits.

The lip gap of the die is preferably 3 times or more and 50 times or less, more preferably 5 times or more and 40 times or less with respect to the sheet thickness. If the lip gap of the die is less than three times the sheet thickness, the effect of stretching the polymer sheet melt-extruded from the die is reduced, and the thickness accuracy of the polymer sheet is deteriorated. If it exceeds 50 times, it is difficult to adjust the thickness, causing a large variation in thickness. In addition, depending on the capacity of the extruder, it may not be possible to extrude the sheet.

After the thermoplastic polymer sheet is extruded from the lip of the die, the distance until it comes into contact with the metal belt, generally called the air gap, is 10 mm or more.
It is preferably 0 mm or less, more preferably 30 mm or more and 70 mm or less. The smaller the air gap, the better the thickness accuracy tends to be.
In order to make the diameter less than 0 mm, it is necessary to reduce the diameter of the roll and make the tip of the lip of the die along the roll, and the roll should be made smaller than the bending stress of the metal belt. There is a limit.

The shape of the die slip is restricted due to the resin pressure, temperature distribution, and the like, and it is difficult to reduce the shape to less than 10 mm. When the air gap exceeds 100 mm, the neck-in is large and the thickness accuracy is deteriorated due to the influence of the neck-in. In addition, since the film is cooled in the atmosphere and stretched and adjusted in a non-uniform temperature distribution, the thickness accuracy is increased. Gets worse.

The length of the metal belt is preferably at least 20 seconds, more preferably at least 30 seconds, at a position where there is no curvature in the flow direction of the polymer sheet. If a metal belt having a cooling time of less than 20 seconds is used, the polymer sheet will not be sufficiently cooled, causing the sheet to warp.

The temperature (V1) of the metal belt that the thermoplastic polymer sheet melt-extruded from the die slip first contacts with the glass transition point (Tg) of the thermoplastic polymer is Tg−10 ≦ V1 ≦ Tg + 150. (° C.), more preferably Tg ≦ V1 ≦ Tg + 120.
(° C.). If V1 is less than Tg-10 ° C., the polymer sheet melt-extruded from the die is rapidly cooled, resulting in poor appearance called cooling wrinkles. In the case of a crystalline polymer, crystallization does not progress and paper abrasion occurs The weight loss due to increases. If V1 is equal to or higher than Tg + 150 ° C., the polymer sheet may be thermally decomposed in addition to cooling at a temperature higher than the die temperature.

The temperature (V2; intermediate portion) of the metal belt having no curvature in the sheet flow direction is Tg−30 ≦ V2 ≦ Tg
+50 (° C.), more preferably Tg
−30 ≦ V2 ≦ Tg + 30. The temperature of V2 is Tg-
When the temperature is lower than 30 ° C., cooling wrinkles are generated as in the case of the temperature of V1, and the progress of crystallization by rapid cooling is hindered, and the wear resistance is deteriorated. If the temperature exceeds Tg + 50 ° C., solidification of the polymer sheet is not sufficiently performed, and there is a problem that sheet warpage occurs. The temperature condition of V2 may be changed so that the temperature decreases with respect to the flow of the sheet on the metal belt having no curvature.

Temperature of the metal belt when the polymer sheet cooled by the metal belt separates from the metal belt (V3)
Is preferably Tg−50 ≦ V3 ≦ Tg (° C.), and more preferably Tg−40 ≦ V3 ≦ Tg−10 (° C.). When the temperature of V3 is lower than Tg-50 ° C., cooling wrinkles are generated. When the temperature exceeds Tg ° C., when the polymer sheet is separated from the metal belt, the polymer sheet and the metal sheet are melted and adhered to each other, causing poor appearance. . Further, V1, V2, V3
Is preferably in a relationship of V3 ≦ V2 ≦ V1 (° C.), and if not, efficient cooling of the polymer sheet will not be performed.

Further, by setting the surface of the polymer sheet in contact with the metal belt and the surface temperature of the polymer sheet on the opposite side to the same temperature as the metal belt side,
The temperature distribution in the thickness direction of the polymer sheet can be reduced, and the warpage of the polymer sheet due to heat history can be improved. In this case, substantially the same temperature means that the difference between the temperatures is within 20 ° C., preferably within 10 ° C. If the temperature difference exceeds 20 ° C., the polymer sheet will be warped. As a method for heating the opposite surfaces of the metal belt and the polymer sheet, infrared heater heating, far-infrared heater heating, a heating medium oil, steam, or the like can be considered, but any method can be used.

In order to adhere the polymer sheet melt-extruded from the die to the metal belt, air controlled at the same temperature as that of the metal belt is blown, or the polymer sheet is brought into close contact by charging and fixed. You may nip.

The polymer sheet produced by such a production method has good thickness accuracy, has little curl, and can be used as a spacer for maintaining a highly accurate gap. Further, it has good abrasion resistance and can be sufficiently used as a spacer for polishing a Si wafer or the like.

The optical properties of the sheet of the present invention were measured by the following methods. (1) Sheet thickness A contact type dial gauge is used to measure the width of the polymer sheet in the width direction.
Average value measured at mm intervals. (2) Thickness tolerance in the sheet surface (Rmax) A contact type dial gauge is used in the width direction of the polymer sheet.
Difference between maximum and minimum values measured at mm intervals.

(3) Warpage of the polymer sheet A length of 300 mm in the flow direction of the polymer sheet and 3 in the width direction.
The height of the polymer sheet, which is the largest away from the surface of the surface plate, when the square sample cut to a length of 00 mm is placed with the front side of the polymer sheet up and down with respect to the surface plate, The maximum value was measured as the warpage of the sheet.

(4) Weight reduction due to taper wear Using a wear wheel of CS17WHEEL with a load of 1 kg,
Measure the weight difference when rotating 1000 times. (ATSM-D
1044)

[0031]

The present invention will be described below with reference to examples and comparative examples. << Example 1 >> Polyetheretherketone resin manufactured by Sumitomo Chemical Co., Ltd .: Victrex PEEK (Tg = 143)
C) using a die with a lip gap of 3 mm, a metal belt and a die arranged so that the air gap is 40 mm, and the polymer sheet extruded from the die is in contact with the flow direction without curvature. The length of the metal belt is 1.
When a 5 m metal belt was used, the contact time was 22 seconds. The temperature (V1) of the metal belt is 220
° C, the temperature of (V2) is 130 ° C, and the temperature of (V3) is 10
At 0 ° C, the surface of the polymer sheet opposite to the surface in contact with the metal belt was heated by an infrared heater, and the temperature was substantially the same as the sheet surface temperature of the metal belt (measured with a thermocouple, The resin temperature on the side was 132 ° C. and the opposite side was 127 ° C.), and a sheet having a thickness of 600 μm was formed. As a result, the thickness tolerance (Rmax) in the plane of the polymer sheet is 3 μm, the amount of warpage of a 300 mm square sheet is 2 mm, and the weight loss due to taper wear is 7 mg / 1000 revolutions. Was obtained.

When a Si wafer for semiconductors was polished using the polymer sheet obtained in Example 1, the thickness accuracy of the Si wafer could be polished with a thickness of 2 μm. It was good without any scratches visually. When a circuit was formed on the obtained Si wafer and a continuity test was performed, no short circuit was confirmed.

<< Comparative Example 1 >> Under the conditions of <Example 1>, when the lip gap of the die was set to 1 mm, uneven lines called die lines were generated, and the thickness tolerance (Rmax) within the polymer sheet plane was reduced. 13 μm. When the Si wafer for semiconductor was polished by using the above polymer sheet, the thickness accuracy of the Si wafer became 18 μm, and it was not possible to function as a spacer.

<Comparative Example 2> Under the conditions of <Example 1>, when a die and a metal belt were arranged such that the air gap was 130 mm, the thickness tolerance (R
max) was 30 μm. When a semiconductor Si wafer was polished by using the above polymer sheet, the thickness accuracy of the Si wafer was 25 μm, and the wafer could not function as a spacer.

<< Comparative Example 3 >> Under the conditions of << Example 1, >> V
When the temperature of Sample No. 1 was set to 120 ° C., the appearance was deteriorated due to cooling wrinkles due to rapid cooling, and crystallization did not proceed.
The result was 0 times. When the Si wafer for semiconductors was polished using the above polymer sheet, the thickness accuracy of the Si wafer could be polished at 6 μm. However, the reproducibility and reliability of the PEEK film were polished together. It wasn't something you could do. In addition, some scratches were visually observed in the polishing direction in appearance. When a circuit was formed on the obtained Si wafer and a continuity test was performed, no short circuit was confirmed.

<< Comparative Example 4 >> Of the conditions of << Example 1, >> V
When the temperature of No. 2 was set to 220 ° C., the warpage of the 300 mm square sheet became 15 mm. When an attempt was made to polish a Si wafer for semiconductor using the above polymer sheet, it was difficult to put the Si wafer in a regular position due to the warpage of the polymer sheet. In that state, S
When the i-wafer was polished, the polished wafer was displaced, and there was a problem in productivity. << Comparative Example 5 >> Within the conditions of << Example 1, >> the temperature of V2 was set to 1
When the temperature was set to 00 ° C., cooling wrinkles occurred. Further, when a taper abrasion test was performed, it was deteriorated to 15 mg / 1000 times.

<< Comparative Example 6 >> Of the conditions of << Example 1, >> V
When the temperature of No. 3 was set to 160 ° C., the sheet was partially fused when the sheet was separated from the metal belt, resulting in poor appearance, and a 300 mm square sheet having a warpage of 10 mm. When an attempt was made to polish a Si wafer for semiconductor using the above-mentioned polymer sheet, it was difficult to put the Si wafer in a steady position due to the warpage of the polymer sheet. When the Si wafer was polished in that state,
A positional shift occurs in the polished wafer, which causes a problem in productivity. << Comparative Example 7 >> Under the conditions of <Example 1>, the V3 temperature was set to 60.
When the temperature was set to ° C., cooling wrinkles occurred, and the sheet floated from the metal belt due to the cooling wrinkles, slipping occurred, and scratches on the film surface were confirmed.

<< Comparative Example 8 >> Under the conditions of <Example 1>, the infrared heater on the surface opposite to the surface of the polymer sheet in contact with the metal belt was not used.
The amount of warpage of the m-square sheet was 8 mm. When an attempt was made to polish a Si wafer for semiconductor using the above-mentioned polymer sheet, it was difficult to put the Si wafer in a steady position due to the warpage of the polymer sheet. In addition, when the Si wafer was polished in this state, the polished wafer was displaced, and there was a problem in productivity.

[0039]

According to the present invention, a thermoplastic polymer sheet having excellent thickness accuracy, less warpage of the substrate, and high abrasion resistance has been developed. Further, the sheet obtained by the present invention is most suitable for a spacer for maintaining a gap with high precision, and is useful as a spacer for polishing a Si wafer for a semiconductor, polishing a glass for a display device, and the like.

Claims (6)

[Claims] 1. A time period in which a thermoplastic polymer sheet melt-extruded from a T-die or a coat hanger is in contact with a flow direction of the thermoplastic polymer sheet extruded from a die without any curvature. A method for producing a thermoplastic polymer sheet, comprising forming a cooling sheet using a metal belt having a length of 20 seconds or more. 2. The temperature (V1) of the metal belt in the first portion where the thermoplastic polymer sheet comes into contact with the metal belt is:
Tg−10 ≦ V with respect to the melting point (Tg) of the thermoplastic polymer
The temperature (V2) of the metal belt, which is in the range of 1 ≦ Tg + 150 (° C.) and has no curvature in the flow direction of the thermoplastic polymer sheet, is in the range of Tg−30 ≦ V2 ≦ Tg + 50 (° C.). The temperature (V3) of the portion of the metal belt where the separated thermoplastic polymer sheet is separated from the metal belt
Is Tg-50 ≦ V3 ≦ Tg (° C.), and V3
The method for producing a thermoplastic polymer sheet according to claim 1, wherein ≤ V2 ≤ V1 (° C). 3. The thermoplastic resin according to claim 1, wherein the surface temperature of the thermoplastic polymer sheet in contact with the metal belt and the surface temperature on the opposite side of the polymer sheet are substantially the same. A method for producing a polymer sheet. 4. The lip gap of the T-die or the coat hanger die is 3 to the thickness of the thermoplastic polymer sheet.
2. The method according to claim 1, wherein the distance from when the thermoplastic polymer sheet is extruded from the lip of the die to when it contacts the metal belt is from 10 mm to 100 mm. A method for producing a thermoplastic polymer sheet. 5. The thermoplastic polymer sheet melt-extruded by the T die or the coat hanger die is a crystalline resin, and has a thickness of 300 μm or more and 1000 μm or more.
The thickness tolerance in the plane of the polymer sheet (Rma
2. The method for producing a thermoplastic polymer sheet according to claim 1, wherein x) is 10 μm or less, the amount of warpage of a 300 mm square sheet is 5 mm or less, and weight loss due to taper wear is 10 mg / 1000 rotations or less. 6. The method for producing a thermoplastic polymer sheet according to claim 1, wherein the thermoplastic polymer sheet is a polyetheretherketone.