JP2002069422A - Thermally foamed type pressure sensitive adhesive and its pressure sensitive adhesion member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure sensitive adhesive and a pressure sensitive adhesion member using the same capable of applying with good adhesion properties with various adherends, particularly a silicon wafer, ceramic sheet, green sheet laminate or the like, easy in application with high tack properties (initial adhesive strength) and high adhesive strength, capable of re-applying without breaking the adherends, and having good release properties by reducing the adhesive strength through heat treatment. SOLUTION: The thermally foamed type pressure sensitive adhesive comprises an adhesive including a base polymer and a foaming agent formulated therein, the base polymer comprising a polymer having the dynamic elasticity within a range of 1.0 to 4.5 N/cm2 within a range of 120 to 150 deg.C wherein the adhesive strength is reduced or lost due to expansion or foaming of the foaming agent through the heat treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-foamable pressure-sensitive adhesive and a pressure-sensitive adhesive member using the same, and more particularly, to a silicon wafer,
The present invention relates to a heat-foamable pressure-sensitive adhesive which is most suitable for use in cutting ceramic sheets or green sheet laminates, and a pressure-sensitive adhesive member using the same.

[0002]

2. Description of the Related Art Conventionally, there has been known a heat-foaming type pressure-sensitive adhesive member for reducing or eliminating the pressure-sensitive adhesive force of a pressure-sensitive adhesive layer by heat treatment, and for easily peeling a pressure-sensitive adhesive member whose intended use has been completed from an adherend. Many have been proposed. One of the uses of this adhesive member is temporary fixing during dicing of a silicon wafer, a ceramic sheet or a green sheet laminate, and the like.
With this member, cut pieces such as silicon wafers can be efficiently collected with good yield. However, the performance required of the heat-foamable pressure-sensitive adhesive member has been enhanced, and particularly in the case of a temporary fixing member, high tackiness (initial pressure).
In addition, it is necessary to have high adhesive strength and to easily peel off from the adherend by heat treatment. Patent No. 2
Japanese Patent Application Laid-Open No. 970963 proposes a heat-foamable pressure-sensitive adhesive member using a base polymer having a high modulus of elasticity from room temperature to 150 ° C. in order to provide the temporary fixing member.

[0003] However, such an adhesive member has poor tackiness (initial adhesive strength) and adhesive strength because reattachment is prioritized, so that an adherend cannot be adhered with good adhesion. In such a case, there is a problem that the air bubbles are easily entrained, so that the ease of application and the workability are reduced. As described above, if the reattachment is prioritized, the ease of application is reduced, and it is difficult to simultaneously improve the performances of the two. At present, one of the performances is prioritized.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to be able to adhere to various adherends, particularly a silicon wafer, a ceramic sheet or a green sheet laminate, with good adhesion, and to have high tackiness (initial tackiness). Pressure-sensitive adhesive with excellent adhesiveness and high adhesive strength, and can be re-attached without damaging the adherend, and has good peelability due to a decrease in adhesive strength due to heat treatment, and an adhesive using the same. It is to provide a member.

[0005]

Means for Solving the Problems The above-mentioned problems are 120 to 1
Dynamic elastic modulus at 50 ° C. is 1.0 to 4.5 N / cm ^Two
Foamed into an adhesive with a polymer in the range of
To provide an adhesive characterized by incorporating an adhesive
More resolved. In addition, the above-mentioned problem is solved on one side of the supporting substrate.
Or an adhesive member provided with the adhesive layer on both sides.
It is solved by.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION
If the dynamic elastic modulus at ~ 150 ° C is too large, the tackiness (initial adhesive strength) and the adhesiveness are poor and the adhesive cannot be adhered to the adherend with good adhesion. is inferior to the serial resistance cemented force) and the adhesive force is too large, 1.0~4.5N / cm ²
It is preferably 30,000 to 4.5 N / cm ² .

In the present invention, the dynamic elastic modulus is set to 120 to 1
The reason why the temperature is specified in the temperature range of 50 ° C. is that the temperature at which the blowing agent is foamed is generally in this temperature range. That is, it has been found that the function relating to the present invention can be exhibited as long as the dynamic elastic modulus in such a temperature range can be specified.

There is no particular limitation on the monomer component or the like forming the polymer having the dynamic elastic modulus. Any of the known monomer components used for preparing pressure-sensitive adhesives such as an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, and a styrene / conjugated diene block copolymer-based pressure-sensitive adhesive can be used.

Specific examples thereof include methyl, ethyl, propyl, butyl, 2-ethylhexyl, isooctyl, isononyl, isodecyl, dodecyl, lauryl, tridecyl, pentadecyl, hexadecyl, Heptadecyl group, octadecyl group, nonadecyl group, acrylic acid or methacrylic acid having an alkyl group having 20 or less carbon atoms, itaconic acid, hydroxyethyl acrylate group, hydroxyethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, such as eicoxyl group, Examples include hydroxypropyl methacrylate, N-methylolacrylamide, acrylonitrile, methacrylonitrile, glycidyl acrylate, vinyl acetate, styrene, isoprene, butadiene, isobutylene, vinyl ether, and the like.

[0010] Natural rubber or recycled rubber that satisfies the above polymer conditions can also be used as the base polymer.

In the preparation of the heat-foamable pressure-sensitive adhesive, a suitable additive such as a crosslinking agent, a tackifier resin, a plasticizer, a filler, an antioxidant, etc. may be used in combination, if necessary.

[0012] A foaming agent is blended with the thermofoamable pressure-sensitive adhesive.
This makes it possible to obtain a heat-foamable pressure-sensitive adhesive in which the adhesive strength is reduced or disappears due to expansion or foaming of the contained foaming agent due to the heat treatment. The amount of the foaming agent may be appropriately determined depending on the degree of reducing the adhesive strength. Generally, 1 to 100 parts by weight, preferably 5 parts by weight, per 100 parts by weight of the base polymer.
５０50 parts by weight.

Examples of the foaming agent include inorganic and organic foaming agents. Examples of the inorganic foaming agent include ammonium carbonate, ammonium hydrogen carbonate, sodium hydrogen carbonate, ammonium nitrite, sodium borohydride, and azides.

Examples of the organic blowing agent include water, chloroalkanes such as trichloromonofluoromethane and dichloromonofluoromethane, azo compounds such as azobisisobutyronitrile, azodicarbonamide, and barium azodicarboxylate; Hydrazine-based compounds such as paratoluenesulfonylhydrazide, diphenylsulfone-3,3'-disulfonylhydrazide, 4,4'-oxybis (benzenesulfonylhydrazide) and allylbis (sulfonylhydrazide); ρ-toluylenesulfonyl semicarbazide; Semicarbazide compounds such as' -oxybis (benzenesulfonylsemicarbazide);
Triazole compounds such as morpholyl-1,2,3,4-thiatriazole, N, N'-dinitrosopentamethylenetetramine and N, N'-dimethyl-N, N'-
N-nitroso-based compounds such as dinitrosoterephthalamide and the like can be mentioned.

The heat-expandable microparticles in which a foaming agent is microencapsulated are preferably used because the mixing operation is easy. Examples of the thermally expandable fine particles include microspheres (trade name: manufactured by Matsumoto Yushi Co., Ltd.). In addition, you may add a foaming auxiliary as needed.

The pressure-sensitive adhesive member of the present invention has a support substrate and a heat-foamable pressure-sensitive adhesive laminated on one or both sides of the support substrate. When a heat-expandable pressure-sensitive adhesive is laminated on one side of the support substrate, a conventional pressure-sensitive adhesive other than the heat-expandable pressure-sensitive adhesive may be laminated on the other side.

The supporting substrate includes a plastic film,
It can be appropriately selected from paper, woven fabric, nonwoven fabric, metal foil, a laminate thereof, a foam, and the like. The thickness is generally 5 μm to 5 mm, but is not limited to this.

Further, in order to improve the adhesion between the support base material and the thermofoamable pressure-sensitive adhesive layer, the surface of the support base material may be treated by physical means such as corona treatment, if necessary, or a urethane or acrylic base may be used. An intermediate pressure-sensitive adhesive layer of a compound or the like can be provided between the heat-foamable pressure-sensitive adhesive layer and the support substrate, and can be subjected to a chemical treatment such as an anchor treatment for improving the adhesion between the two by an anchor effect. In addition, in order to prevent the adhesive strength of the heat-foamable adhesive layer from lowering due to the adhesion of dust and oil, it is preferable to protect the surface with a separator such as a plastic film until use.

The thickness of the heat-foamable pressure-sensitive adhesive layer provided on the supporting substrate can be appropriately determined, and is generally 1 to 500 μm, preferably 5 to 100 μm.

The heat-foamable pressure-sensitive adhesive of the present invention can be used in various applications that require easy peeling and removal from the adherend after the purpose of the adherence is completed after being adhered to the adherend. As an example, there is a temporary fixing member when a semiconductor chip is obtained by cutting a silicon wafer, or when a capacitor chip is obtained by cutting a ceramic sheet.

The adhesive strength of the heat-foamable pressure-sensitive adhesive can be reduced or eliminated by expanding or foaming the foaming agent in the heat-foamable pressure-sensitive adhesive layer by heat treatment. The conditions for the heat treatment can be appropriately determined depending on the foaming characteristics, the heat resistance of the supporting substrate used for the adhesive member, and the like. The heat treatment can be performed at an appropriate stage depending on the purpose of use.

[0022]

EXAMPLES Examples of the present invention will be described below in detail with reference to Table 1 in comparison with Comparative Examples. Here, Table 1 shows the characteristic values of the examples according to the present invention and the comparative examples.

[0023]

[Table 1]

The dynamic elastic modulus in Table 1 is measured by RDA-I manufactured by Rheometric Scientific F.E.
According to I, the value G ′ at 120 to 150 ° C. of the base polymer used for preparing the thermofoamable pressure-sensitive adhesive was measured. This measurement was performed by sandwiching the base polymer between two plates, rotating one plate, and detecting the torque received by the other plate.

The tackiness (initial adhesive strength) in Table 1 is
It was measured according to the probe tack method, JIS Z0237. This value is preferably 4.0 to 7.0 N / 20 mm ² .

The "easiness of sticking" in Table 1 means that the adhesive members obtained in Examples and Comparative Examples were applied to a silicon wafer (hereinafter abbreviated as an adherend) as an adherend by a manual crimping device (2 kg). Lamination and the presence or absence of air bubbles were visually observed to evaluate the degree of entrapment of air bubbles at the time of lamination. The case where no air bubble was present was regarded as “good”.

"Easy reattachment" in Table 1 means that the adhesive member obtained in each of Examples and Comparative Examples was attached to an adherend after bonding.
The adhesive member was peeled off by hand at an angle of 80 °, and the ease of reattachment when correcting the position of the adherend was evaluated. The case where the adherend was not damaged at all when peeled by hand was regarded as “good”.

The adhesive strength in Table 1 was measured for the adhesive members obtained in the examples and comparative examples, at room temperature and after heat treatment, on the adherend according to JIS Z0237. The heat treatment conditions were as follows: oven temperature 150 ° C, 1
Minutes. Adhesion at room temperature is 4.0 to 10.0 N / 2
0 mm is preferable, and the adhesive strength after the heat treatment is 0.0
The range of about 0.2 N / 20 mm is preferable.

The “peelability after heat treatment” in Table 1 was evaluated as to whether or not the film could be peeled by hand after the heat treatment under the above conditions. In addition, when it peeled without applying force when peeling by hand, it was set as "good".

The heat-foamable pressure-sensitive adhesive of Example 1 was a base poly
1.0N / cm dynamic elastic modulus ^TwoEthyl acrylate
100-fold copolymer of 2-ethylhexyl acrylate
Parts, 1 part by weight of isocyanate-based cross-linking agent, heat-expandable fine particles
9 parts by weight of microsphere (F-30D)
It was done. Dissolve this hot foam type adhesive in toluene
To a solution, the solution is 100 μm thick polyethylene
Thickness after drying on one side of terephthalate film is 40μ
m to obtain a thermally foamed pressure-sensitive adhesive member.

The heat-foamable pressure-sensitive adhesive according to Example 2 was prepared by mixing 100 parts by weight of a copolymer of ethyl acrylate-2-ethylhexyl acrylate having a dynamic elastic modulus of 2.8 N / cm ² as a base polymer, and isocyanate-based crosslinking. The heat-foamable pressure-sensitive adhesive member of Example 2 had a thickness of 50 μm after drying, except that 5 parts by weight of the material and 12 parts by weight of the heat-expandable fine particles were used. This was formed in the same manner as in Example 1 except that the heat-foamable pressure-sensitive adhesive of Example 2 was applied as described above.

The heat-foamable pressure-sensitive adhesive according to Example 3 was prepared by using 100 parts by weight of a copolymer of ethyl acrylate-2-ethylhexyl acrylate having a dynamic elastic modulus of 4.5 N / cm ² as a base polymer, and isocyanate-based crosslinking. It was formed in the same manner as in Example 1 except that the material was changed to 6 parts by weight and the heat-expandable fine particles were changed to 15 parts by weight. This was formed in the same manner as in Example 1 except that the heat-foamable pressure-sensitive adhesive of Example 3 was applied as described above.

Comparative Example 1 is the same as Example 1 except that natural rubber having a dynamic elastic modulus of 0.5 N / cm ² was used as the base polymer.

In Comparative Example 2, ethyl acrylate-acrylic acid 2 having a dynamic elastic modulus of 4.7 N / cm ² was used as the base polymer.
Comparative Example 2 was formed in the same manner as in Example 1 except that the copolymer of -ethylhexyl was 100 parts by weight, the isocyanate-based crosslinking material was 10 parts by weight, and the thermally expandable fine particles were 10 parts by weight. The mold pressure-sensitive adhesive member was formed in the same manner as in Example 1 except that the heat-foamable pressure-sensitive adhesive of Comparative Example 2 was applied so that the thickness after drying was 40 μm.

Comparative Example 1, Examples 1, 2, 3 and Comparative Example 2
As shown, the dynamic elastic modulus at 150 ° C. is 1.0 to
A pressure-sensitive adhesive obtained by blending a foaming agent with a base polymer in the range of 4.5 N / cm ² has excellent tackiness, excellent ease of application and good re-application, no entrapment of air bubbles during bonding, and heat treatment. A heat-foamable pressure-sensitive adhesive and a pressure-sensitive adhesive member having excellent peelability afterwards were obtained.

On the other hand, as can be seen from Comparative Example 1,
In the case of a heat-foamable pressure-sensitive adhesive using a base polymer having a low dynamic elastic modulus, the adhesive force at room temperature is too large, so that the silicon wafer as an adherend is damaged during re-attachment and cannot be successfully re-attached. . Further, the adhesive strength after the heat treatment did not decrease much, and the silicon wafer could not be peeled off from the adhesive.

Further, as can be seen from Comparative Example 2, the heat-foamable pressure-sensitive adhesive using a base polymer having a high dynamic elastic modulus
Poor tackiness, many air bubbles involved during lamination, lacked stability when fixing the adherend, lacked ease of application, and low adhesion.

[0038]

According to the present invention, the base polymer having a dynamic elastic modulus at 120 to 150 ° C. in the range of 1.0 to 4.5 N / cm ² is used as the heat-foamable pressure-sensitive adhesive. It can be adhered to the body with good adhesiveness, has high tackiness (initial adhesive strength) and high adhesive strength, is easy to re-attach, and has excellent adhesive strength lowering property due to heat treatment. Disappears, the adherend can be easily peeled off. In particular, when used as a temporary fixing adhesive member for cutting a semiconductor wafer or the like, a cut piece can be efficiently collected, and thus an adhesive member useful for speeding up and automating the manufacturing process can be provided.

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Claims (2)

[Claims] 1. A hot-foaming type composition comprising a pressure-sensitive adhesive comprising a polymer having a dynamic elastic modulus in the range of 120 to 150 ° C. in the range of 1.0 to 4.5 N / cm ² and a foaming agent. A heat-foamable pressure-sensitive adhesive, wherein the pressure-sensitive adhesive strength is reduced or eliminated by expansion or foaming of the foaming agent due to heat treatment. 2. A pressure-sensitive adhesive member comprising: a support substrate; and the heat-foamable pressure-sensitive adhesive according to claim 1 laminated on one or both surfaces of the support substrate.