U.S. patent application number 11/067204 was filed with the patent office on 2005-08-11 for method for processing an electronic part.
This patent application is currently assigned to Asahi Kasei Chemicals Corporation. Invention is credited to Mitarai, Yoshiaki.
Application Number | 20050173052 11/067204 |
Document ID | / |
Family ID | 30769544 |
Filed Date | 2005-08-11 |
United States Patent
Application |
20050173052 |
Kind Code |
A1 |
Mitarai, Yoshiaki |
August 11, 2005 |
Method for processing an electronic part
Abstract
Disclosed is a gas-generating, pressure-sensitive adhesive
composition comprising a pressure-sensitive adhesive (A)
transmitting therethrough a radiation selected from the group
consisting of an electromagnetic radiation, an electron radiation
and an alpha radiation, and a gas generator compound (B) which
generates a gas upon irradiation thereof with the radiation,
wherein the gas generator compound (B) is operably combined with
the pressure-sensitive adhesive (A), so that, in operation, when
the gas-generating, pressure-sensitive adhesive composition which
is adhered to an adherend is irradiated with the radiation, the gas
generator compound (B) generates a gas and the gas effuses at an
interface between the gas-generating, pressure-sensitive adhesive
composition and the adherend to thereby facilitate release of the
adherend from the gas-generating, pressure-sensitive adhesive
composition.
Inventors: |
Mitarai, Yoshiaki;
(Ooita-shi, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
Asahi Kasei Chemicals
Corporation
|
Family ID: |
30769544 |
Appl. No.: |
11/067204 |
Filed: |
February 28, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11067204 |
Feb 28, 2005 |
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10200495 |
Jul 23, 2002 |
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6864295 |
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Current U.S.
Class: |
156/247 ;
156/272.2; 156/712; 156/750; 156/937 |
Current CPC
Class: |
H01L 21/67132 20130101;
H01L 21/6835 20130101; B29C 65/76 20130101; H01L 21/6836 20130101;
H01L 2924/19041 20130101; Y10T 428/287 20150115; C09J 11/06
20130101; Y10T 156/1158 20150115; B29C 65/76 20130101; Y10T
428/2809 20150115; Y10T 156/19 20150115; B29C 66/9161 20130101;
C09J 2203/326 20130101; H01L 2221/68318 20130101; Y10T 428/2891
20150115; H01L 2221/68327 20130101; C09J 5/00 20130101; B29C 65/00
20130101 |
Class at
Publication: |
156/247 ;
156/272.2; 156/344 |
International
Class: |
B32B 031/00 |
Claims
1. A method for processing an electronic part, comprising: (1)
applying a gas-generating, pressure-sensitive adhesive reagent to a
surface of a substratum to provide a gas-generating,
pressure-sensitive adhesive hybrid, wherein said gas-generating,
pressure-sensitive adhesive reagent generates a gas upon
irradiation thereof with a radiation selected from the group
consisting of an electromagnetic radiation, an electron radiation
and an alpha radiation, and wherein said substratum transmits said
irradiation; (2) securely attaching one surface of an electronic
part onto a gas-generating, pressure-sensitive adhesive
reagent-side surface of said gas-generating, pressure-sensitive
adhesive hybrid, wherein the other surface of said electronic part
is left exposed; (3) working said exposed surface of the electronic
part; (4) irradiating said gas-generating, pressure-sensitive
adhesive reagent with said radiation through said substratum, to
thereby cause said pressure-sensitive adhesive reagent to generate
a gas, so that the gas effuses at an interface between said
gas-generating, pressure-sensitive adhesive reagent and said
electronic part; and (5) detaching said electronic part from said
adhesive hybrid.
2. The method according to claim 1, wherein said adhesive reagent
is a gas-generating, pressure-sensitive adhesive composition
comprising: a pressure-sensitive adhesive (A) transmitting
therethrough a radiation selected from the group consisting of an
electromagnetic radiation, an electron radiation and an alpha
radiation; and a gas generator compound (B) which generates a gas
upon irradiation thereof with said radiation, said gas generator
compound (B) being operably combined with said pressure-sensitive
adhesive (A), so that, in operation, when the gas-generating,
pressure-sensitive adhesive composition which is adhered to an
adherend is irradiated with said radiation, the gas generator
compound (B) generates a gas and the gas effuses at an interface
between the gas-generating, pressure-sensitive adhesive composition
and the adherend to thereby facilitates release of the adherend
from the gas-generating, pressure-sensitive adhesive
composition.
3. The method according to claim 2, wherein said gas generator
compound (B) is a compound having an azido group.
4. The method according to claim 3, wherein said gas generator
compound (B) is a compound having an organic azido group.
5. The method according to claim 4, wherein said gas generator
compound (B) is a compound having an azidomethyl group.
6. The method according to claim 2, wherein said gas generator
compound (B) is at least one compound selected from the group
consisting of 3-azidomethyl-3-methyloxetane,
3,3'-bis(azidomethyl)oxetane and a glycidyl azide polymer.
7. The method according to claim 2, wherein said adhesive (A)
comprises at least one compound selected from the group consisting
of a rubber polymer, an acrylic polymer, a polyether, a polyester,
a polyisocyanate and a polyurethane.
8. The method according to claim 7, wherein said adhesive (A)
further comprises a photopolymerizable oligomer.
9. The method according to claim 8, wherein said adhesive (A) is
curable upon irradiation thereof with a radiation selected from the
group consisting of an electromagnetic radiation, an electron
radiation and an alpha radiation.
10. The method according to claim 9, wherein said radiation is an
ultraviolet radiation.
11. The method according to claim 1, wherein said gas-generating,
pressure-sensitive adhesive reagent is a gas-generating,
pressure-sensitive adhesive polymer which generates a gas upon
irradiation thereof with a radiation selected from the group
consisting of an electromagnetic radiation, an electron radiation
and an alpha radiation.
12. The method according to claim 11, wherein said gas-generating,
pressure-sensitive adhesive polymer is a glycidyl azide
polymer.
13. The method according to claim 1, wherein said
pressure-sensitive adhesive hybride is an adhesive tape or sheet,
comprising a substratum tape or sheet having applied thereto the
adhesive reagent.
14. The method according to claim 13, wherein said adhesive reagent
has a thickness of from 0.005 to 1 mm.
15. The method according to claim 1, wherein said radiation used in
step (4) is an ultraviolet radiation.
16. The method according to claim 1, wherein said electronic part
is a precision electronic part.
17. The method according to claim 1, wherein said electronic part
is a substrate for an electronic appliance.
18. The method according to claim 1, wherein said electronic part
is a semiconductor part, and wherein the working in said step (3)
is selected from the group consisting of (i) a grinding of said
exposed surface of the semiconductor part, and (ii) a cutting of
said semiconductor part in a thicknesswise direction thereof from
said exposed surface of said semiconductor part.
19. The method according to claim 18, wherein said semiconductor
part is a semiconductor wafer.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a gas-generating,
pressure-sensitive adhesive composition. More particularly, the
present invention is concerned with a gas-generating,
pressure-sensitive adhesive composition comprising: a
pressure-sensitive adhesive (A) transmitting therethrough a
radiation selected from the group consisting of an electromagnetic
radiation, an electron radiation and an alpha radiation; and a gas
generator compound (B) which generates a gas upon irradiation
thereof with the radiation. In the gas-generating,
pressure-sensitive adhesive composition of the present invention,
the gas generator compound (B) is operably combined with the
pressure-sensitive adhesive (A), so that, in operation, when the
gas-generating, pressure-sensitive adhesive composition which is
adhered to an adherend is irradiated with the radiation, the gas
generator compound (B) generates a gas and the gas effuses at an
interface between the gas-generating, pressure-sensitive adhesive
composition and the adherend to thereby facilitate release of the
adherend from the gas-generating, pressure-sensitive adhesive
composition. Therefore, in the working (e.g., grinding or cutting)
of an electronic part, such as a precision electronic part, a
substrate for an electronic appliance, or a semiconductor part
(e.g., a semiconductor wafer), when the gas-generating,
pressure-sensitive adhesive composition of the present invention is
used as an adhesive for temporarily attaching the electronic part
to a substratum (working platform) or the like, the following
advantages can be obtained. That is, it is possible not only to
attach the electronic part securely to the substratum or the like,
but also to remarkably improve the releasability of the electronic
part from the gas-generating, pressure-sensitive adhesive
composition upon irradiation of the composition with a radiation
(which is generally applied during the processing of the electronic
part), so that, after the working (e.g., grinding or cutting) of
the electronic part, the electronic part can be easily released
from the gas-generating, pressure-sensitive adhesive composition
without putting a high load on the electronic part, Accordingly, by
the use of the gas-generating, pressure-sensitive adhesive
composition of the present invention, the working of an electronic
part can be efficiently conducted without causing breakage of the
electronic part. The present invention is also concerned with a
method for processing an electronic part, such as a precision
electronic part, a substrate for an electronic appliance, or a
semiconductor part (e.g., a semiconductor wafer) by the use of a
specific gas-generating, pressure-sensitive adhesive reagent, such
as the above-mentioned gas-generating, pressure-sensitive adhesive
composition.
[0003] 2. Prior Art
[0004] In recent years, there has been a growing tendency toward
miniaturization of electronic parts, and a large number of
electronic parts having a size of less than 1 mm.times.1 mm (i.e.,
precision electronic parts) have been produced. As examples of such
precision electronic parts, there can be mentioned various types of
semiconductor devices, such as a diode, a transistor, a rectifier,
a thermistor, a varistor and a thyristor: various types of
integrated circuits, such as an IC and an LSI; various types of
capacitors, such as a ceramic capacitor, an aluminum capacitor, a
mica capacitor, an organic film capacitor and a metailized organic
capacitor; organic resistors; various types of crystal devices,
such as a crystal oscillator and a crystal filter; and other
electronic parts which are generally used, such as a connector, a
coil, a transformer, a switch, a magnetic head, a polycrystalline
silicon and a TFT (thin film transistor).
[0005] On the other hand, with respect to substrates for electronic
appliances, there is a tendency toward development of technologies
for multi-layering the substrates. Examples of such substrates
include a glass or polyimide sheet and an electrode sheet
comprising an electroconductive material, such as silver or copper,
wherein precision electronic parts are mounted on the sheet to form
a circuit.
[0006] Especially, with respect to integrated circuits (IC's),
which are incorporated in all electronic appliances, there is a
tendency toward miniaturization and improvement in performance,
thereby promoting development of IC's having a very high density.
For example, a multifunctional device comprising multiple layers of
IC chips is currently under development. Further, with respect to
semiconductor packages, the mounting of chip-size packages is
becoming a standard technology.
[0007] In many cases, precision electronic parts have a fine
structure or a small thickness. Therefore, during the production or
processing of precision electronic parts, a substrate for the
precision electronic part or the electronic part per se is
temporarily attached to a substratum (working platform) using an
adhesive.
[0008] For example, when an electronic part (such as a substrate
for an electronic appliance) is processed, and transferred to or
placed on a substrate to obtain an ultimate article, the electronic
part is temporarily attached onto a temporary substratum using an
adhesive tape or sheet which has a capability of temporarily but
securely attaching the electronic part to the temporary substratum
and a capability of releasing the electronic part after the working
(e.g., grinding or cutting) of the electronic part.
[0009] For example, a multilayer substrate (e.g., a film capacitor)
as a substrate for an electronic appliance can be produced as
follows. A surface (a) of a substrate is attached onto a surface of
an adhesive tape or sheet and, then, the opposite surface (b) of
the substrate is worked. The worked surface (b) is attached onto a
surface of another adhesive tape or sheet. Then, from the surface
(a) of the substrate is released the adhesive tape or sheet to
expose the surface (a), and the exposed surface (a) is worked,
thereby obtaining a worked substrate (both surfaces of which have
been worked). A plurality of such worked substrates are laminated
to produce a multilayer substrate.
[0010] As seen from the above, in the production of precision
electronic parts, adhesives for temporarily attaching the precision
electronic parts to a temporary substratum (working platform) have
come to play a greater role.
[0011] For example, when it is intended to work a precision
electronic part, prior to the working thereof, the precision
electronic part is securely attached onto an adhesive tape or
sheet. After the working of the precision electronic part, it is
necessary to release the precision electronic part from the
adhesive tape or sheet. During such a working of the precision
electronic part, it is required that the adhesive tape or sheet
exhibit a high adhesion strength. On the other hand, when the
resultant worked precision electronic part is picked up from the
adhesive tape or sheet, it is required that the adhesive tape or
sheet exhibit a low adhesion strength (i.e., excellent
releasability).
[0012] A more illustrative explanation is made below, taking as an
example the case where the precision electronic part is a
semiconductor wafer. Generally, dicing of the semiconductor wafer
is conducted by the so-called "direct pickup method". Specifically,
in the "direct pickup method", the semiconductor wafer is securely
attached onto an adhesive tape (dicing tape), followed by cutting
the semiconductor wafer into segments using a rotary blade. Then,
the resultant semiconductor wafer segments on the adhesive tape are
picked up one by one and mounted on a die. On the other hand, in a
grinding (backgrinding) operation conducted for thinning the
semiconductor wafer having a circuit formed thereon, the adhesive
tape is securely attached onto the circuit-side surface of the
semiconductor wafer, and the opposite surface of the semiconductor
wafer is ground. In such workings (dicing and backgrinding) of the
semiconductor wafer, for preventing the semiconductor-wafer from
being broken or preventing the semiconductor wafer segments from
scattering, it is required that the adhesive tape have a high
adhesion strength. On the other hand, when the semiconductor wafer
segments are picked up after the above workings, for preventing the
semiconductor wafer from being broken, it is required that the
adhesive tape have a low adhesion strength (i.e., excellent
releasability).
[0013] Nowadays, with respect to semiconductor wafers, there is a
world-wide trend toward enlargement of diameter and reduction in
thickness. As a result, a large number of semiconductor wafers of
today are susceptible to breakage due to external force. Therefore,
it is now required to develop an adhesive tape which can suppress
the load on a semiconductor during the dicing or pick-up thereof.
Needless to say, it is most desired to develop an adhesive tape
which exhibits absolutely no adhesion strength to a semiconductor
wafer during the pickup thereof ("Setchaku (Adhesion)", Vol. 43,
No. 1, pp. 22-25, Kobunshi Kankokai Inc., Japan, 1999).
[0014] In an attempt to meet the requirement, several adhesive
tapes have been proposed, For example, there has been proposed an
irradiation-curable adhesive tape comprising an adhesive layer,
wherein the adhesion strength of the adhesive tape attached to an
adherend can be reduced by curing the adhesive layer by irradiation
of the adhesive tape on the substratum with an ultraviolet
radiation or an ionizing radiation (e.g., an electron radiation)
(Unexamined Japanese Patent Application Laid-Open Specification No.
Hei 1-272130). There has also been proposed an adhesive tape
comprising a water-soluble polymer as an adhesive component,
wherein the adhesive component can be dissolved-out from the
adhesive tape by using hot water after the dicing, thereby reducing
the adhesion strength of the adhesive tape.
[0015] However, the irradiation-curable adhesive tape. even after
curing, still exhibits a high adhesion strength to the electronic
part and, hence, the releasability of the electronic part from the
adhesive tape is unsatisfactory.
[0016] In addition, trays conventionally used for transporting or
mounting electronic parts also have a problem in that, when the
electronic parts are placed on the trays, the electronic parts will
move on the trays, so that the electronic parts are likely to be
damaged by impact or to be influenced by static electricity. For
solving this problem, Unexamined Japanese Patent Application
Laid-Open Specification No. Hei 11-334785 discloses an adhesive
tape for attaching an electronic part to a carrier (tray) used for
transporting or mounting the electronic part. However, the
releasability of an electronic part from the adhesive tape
disclosed in this patent document is unsatisfactory.
[0017] As seen from the above, it has been desired to develop an
adhesive composition having an excellent releasability from an
electronic part.
SUMMARY OF THE INVENTION
[0018] In this situation, the present inventors have made extensive
and intensive studies with a view toward developing an adhesive
composition for temporarily attaching an electronic part (such as a
semiconductor wafer) to a substratum (working platform), which has
an excellent releasability from an electronic part and, hence, is
advantageous in that, after the electronic part is securely
attached to the adhesive composition and worked, the electronic
part can be easily released from the adhesive composition without
putting a high load on the electronic part.
[0019] As a result, it has unexpectedly been found that the desired
adhesive composition can be realized by a specific gas-generating,
pressure-sensitive adhesive composition comprising: a
pressure-sensitive adhesive (A) transmitting therethrough a
radiation selected from the group consisting of an electromagnetic
radiation, an electron radiation and an alpha radiation; and a gas
generator compound (B) which generates a gas upon irradiation
thereof with the radiation. More specifically, in the specific
gas-generating, pressure-sensitive adhesive composition, the gas
generator compound (B) is operably combined with the
pressure-sensitive adhesive (A), so that, in operation, when the
gas-generating, pressure-sensitive adhesive composition which is
adhered to an adherend is irradiated with the radiation, the gas
generator compound (B) generates a gas and the gas effuses at an
interface between the gas-generating, pressure-sensitive adhesive
composition and the adherend to thereby facilitate release of the
adherend from the gas-generating, pressure-sensitive adhesive
composition. Further, in the working (e.g., grinding or cutting) of
an electronic part, such as a precision electronic part, a
substrate for an electronic appliance, or a semiconductor part
(e.g., a semiconductor wafer), when the gas-generating,
pressure-sensitive adhesive composition is used as an adhesive for
temporarily attaching the electronic part to a substratum (working
platform) or the like, various advantageous are brought about. That
is, it is possible not only to attach the electronic part securely
to the substratum or the like, but also to remarkably improve the
releasability of the electronic part from the gas-generating,
pressure-sensitive adhesive composition upon irradiation of the
composition with a radiation (which is generally applied to in the
processing of the electronic part), so that, after the working
(e.g., grinding or cutting) of the electronic part, the electronic
part can be easily released from the gas-generating,
pressure-sensitive adhesive composition without putting a high load
on the electronic part. Based on these novel findings, the present
invention has been completed.
[0020] Accordingly, it is a primary object of the present invention
to provide a gas-generating, pressure-sensitive adhesive
composition which can be used for efficiently conducting the
processing of the electronic part without causing breakage of the
electronic part.
[0021] It is another object of the present invention to provide a
method for efficiently processing an electronic part without
causing breakage of the electronic part, wherein a specific
gas-generating, pressure-sensitive adhesive reagent, such as the
above-mentioned gas-generating, pressure-sensitive adhesive
composition, is used.
[0022] The foregoing and other objects, features and advantages of
the present invention will be apparent from the following detailed
description and appended claims taken in connection with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] In the drawings:
[0024] FIG. 1 is a diagrammatic perspective view of a circular
adhesive sheet attached to a substratum (working platform) by means
of a ring-shaped jig;
[0025] FIG. 2 is a diagrammatic perspective view of the circular
adhesive sheet having a semiconductor wafer adhered to the surface
thereof;
[0026] FIG. 3 is a diagrammatic perspective view of the circular
adhesive sheet having a semiconductor wafer adhered to the surface
thereof, in which the semiconductor wafer is being diced;
[0027] FIG. 4 is a diagrammatic perspective view of the circular
adhesive sheet having a diced semiconductor wafer adhered to the
surface thereof, in which the adhesive sheet is being irradiated
with a UV radiation;
[0028] FIG. 5 is a diagrammatic perspective view of the
UV-irradiated adhesive sheet having the diced semiconductor wafer
placed thereon, in which a collet has been brought into contact
with a target segment of the diced wafer so as to collect the
target segment by suction: and
[0029] FIG. 6 is a diagrammatic perspective view of the
UV-irradiated adhesive sheet having the diced semiconductor wafer
placed thereon, in which the target segment of the diced wafer has
been picked up by the collet.
DESCRIPTION OF THE REFERENCE NUMERALS
[0030] 1 Ring-shaped jig
[0031] 2 Circular adhesive sheet
[0032] 3a Semiconductor wafer
[0033] 3b Segment of the diced semiconductor wafer
[0034] 4 Rotary blade (two arrows indicate, respectively, the
direction of the revolution of the blade and the direction of the
movement of the blade)
[0035] 5 UV lamp
[0036] 6 Collet
[0037] 6a Arm portion of the collet
[0038] 6b Sucking portion of the collet
DETAILED DESCRIPTION OF THE INVENTION
[0039] According to the present invention, there is provided a
gas-generating, pressure-sensitive adhesive composition
comprising:
[0040] a pressure-sensitive adhesive (A) transmitting therethrough
a radiation selected from the group consisting of an
electromagnetic radiation, an electron radiation and an alpha
radiation: and
[0041] a gas generator compound (B) which generates a gas upon
irradiation thereof with the radiation,
[0042] the gas generator compound (B) being operably combined with
the pressure-sensitive adhesive (A), so that, in operation, when
the gas-generating, pressure-sensitive adhesive composition which
is adhered to an adherend is irradiated with the radiation, the gas
generator compound (B) generates a gas and the gas effuses at an
interface between the gas-generating, pressure-sensitive adhesive
composition and the adherend to thereby facilitate release of the
adherend from the gas-generating, pressure-sensitive adhesive
composition.
[0043] For easy understanding of the present invention, important
features and various embodiments of the present invention are
enumerated below.
[0044] 1. A gas-generating, pressure-sensitive adhesive composition
comprising:
[0045] a pressure-sensitive adhesive (A) transmitting therethrough
a radiation selected from the group consisting of an
electromagnetic radiation, an electron radiation and an alpha
radiation; and
[0046] a gas generator compound (B) which generates a gas upon
irradiation thereof with the radiation,
[0047] the gas generator compound (B) being operably combined with
the pressure-sensitive adhesive (A), so that, in operation, when
the gas-generating, pressure-sensitive adhesive composition which
is adhered to an adherend is irradiated with the radiation, the gas
generator compound (B) generates a gas and the gas effuses at an
interface between the gas-generating, pressure-sensitive adhesive
composition and the adherend to thereby facilitate release of the
adherend from the gas-generating, pressure-sensitive adhesive
composition.
[0048] 2. The gas-generating, pressure-sensitive adhesive
composition according to item 1 above, wherein the gas generator
compound (B) is a compound having an azido group.
[0049] 3. The gas-generating, pressure-sensitive adhesive
composition according to item 2 above, wherein the gas generator
compound (B) is a compound having an organic azido group.
[0050] 4. The gas-generating, pressure-sensitive adhesive
composition according to item 3 above, wherein the gas generator
compound (B) is a compound having an azidomethyl group.
[0051] 5. The gas-generating, pressure-sensitive adhesive
composition according to item 1 above, wherein the gas generator
compound (B) is at least one compound selected from the group
consisting of 3-azidomethyl-3-methyloxetane,
3,3-bis(azidomethyl)oxetane and a glycidyl azide polymer.
[0052] 6. The gas-generating, pressure-sensitive adhesive
composition according to item 5 above, wherein the gas generator
compound (B) is a glycidyl azide polymer.
[0053] 7. The gas-generating, pressure-sensitive adhesive
composition according to item 1 above, wherein the adhesive (A)
comprises at least one compound selected from the group consisting
of a rubber polymer, an acrylic polymer, a polyether, a polyester,
a polyisocyanate and a polyurethane.
[0054] 8. The gas-generating, pressure-sensitive adhesive
composition according to item 7 above, wherein the adhesive (A)
further comprises a photopolymerizable oligomer.
[0055] 9. The gas-generating, pressure-sensitive adhesive
composition according to item 8 above, wherein the adhesive (A) is
curable upon irradiation thereof with a radiation selected from the
group consisting of an electromagnetic radiation, an electron
radiation and an alpha radiation.
[0056] 10. The gas-generating, pressure-sensitive adhesive
composition according to item 9 above, wherein the radiation is an
ultraviolet radiation.
[0057] 11. The gas-generating, pressure-sensitive adhesive
composition according to item 1 above, which is in the form of a
sheet or a tape.
[0058] 12. The gas-generating, pressure-sensitive adhesive
composition according to item 11 above, which has a thickness of
from 0.005 to 1 mm.
[0059] 13. A method for processing an electronic part,
comprising:
[0060] (1) applying a gas-generating, pressure-sensitive adhesive
reagent to a surface of a substratum to provide a gas-generating,
pressure-sensitive hybrid, wherein the gas-generating,
pressure-sensitive adhesive reagent generates a gas upon
irradiation thereof with a radiation selected from the group
consisting of an electromagnetic radiation, an electron radiation
and an alpha radiation, and wherein the substratum transmits the
irradiation;
[0061] (2) securely attaching one surface of an electronic part
onto a gas-generating, pressure-sensitive adhesive reagent-side
surface of the gas-generating, pressure-sensitive adhesive hybrid,
wherein the other surface of the electronic part is left
exposed;
[0062] (3) working the exposed surface of the electronic part;
[0063] (4) irradiating the gas-generating, pressure-sensitive
adhesive reagent with the radiation through the substratum, to
thereby cause the pressure-sensitive adhesive reagent to generate a
gas, so that the gas effuses at an interface between the
gas-generating, pressure-sensitive adhesive reagent and the
electronic part; and
[0064] (5) detaching the electronic part from the adhesive
hybrid.
[0065] 14. The method according to item 13 above, wherein the
adhesive reagent is a gas-generating, pressure-sensitive adhesive
composition comprising:
[0066] a pressure-sensitive adhesive (A) transmitting therethrough
a radiation selected from the group consisting of an
electromagnetic radiation, an electron radiation and an alpha
radiation; and
[0067] a gas generator compound (B) which generates a gas upon
irradiation thereof with the radiation,
[0068] the gas generator compound (B) being operably combined with
the pressure-sensitive adhesive (A), so that, in operation, when
the gas-generating, pressure-sensitive adhesive composition which
is adhered to an adherend is irradiated with the radiation, the gas
generator compound (B) generates a gas and the gas effuses at an
interface between the gas-generating, pressure-sensitive adhesive
composition and the adherend to thereby facilitate release of the
adherend from the gas-generating, pressure-sensitive adhesive
composition.
[0069] 15. The method according to item 14 above, wherein the gas
generator compound (B) is a compound having an azido group.
[0070] 16. The method according to item 15 above, wherein the gas
generator compound (B) is a compound having an organic azido
group.
[0071] 17. The method according to item 16 above, wherein the gas
generator compound (B) is a compound having an azidomethyl
group.
[0072] 18. The method according to item 14 above, wherein the gas
generator compound (B) is at least one compound selected from the
group consisting of 3-azidomethyl-3-methyloxetane,
3,3'-bis(azidomethyl)oxetane and a glycidyl azide polymer.
[0073] 19. The method according to item 14 above, wherein the
adhesive (A) comprises at least one compound selected from the
group consisting of a rubber polymer, an acrylic polymer, a
polyether, a polyester, a polyisocyanate and a polyurethane.
[0074] 20. The method according to item 19 above, wherein the
adhesive (A) further comprises a photopolymerizable oligomer.
[0075] 21. The method according to item 20 above, wherein the
adhesive (A) is curable upon irradiation thereof with a radiation
selected from the group consisting of an electromagnetic radiation,
an electron radiation and an alpha radiation.
[0076] 22. The method according to item 21 above, wherein the
radiation is an ultraviolet radiation.
[0077] 23. The method according to item 13 above, wherein the
gas-generating, pressure-sensitive adhesive reagent is a
gas-generating, pressure-sensitive adhesive polymer which generates
a gas upon irradiation thereof with a radiation selected from the
group consisting of an electromagnetic radiation, an electron
radiation and an alpha radiation.
[0078] 24. The method according to item 23 above, wherein the
gas-generating, pressure-sensitive adhesive polymer is a glycidyl
azide polymer.
[0079] 25. The method according to item 13 above, wherein the
pressure-sensitive adhesive hybrid is an adhesive tape or sheet,
comprising a substratum tape or sheet having applied thereto the
adhesive reagent.
[0080] 26. The method according to item 25 above, wherein the
adhesive reagent has a thickness of from 0.005 to 1 mm.
[0081] 27. The method according to item 13 above, wherein the
radiation used in step (4) is an ultraviolet radiation.
[0082] 28. The method according to item 13 above, wherein the
electronic part is a precision electronic part.
[0083] 29. The method according to item 13 above, wherein the
electronic part is a substrate for an electronic appliance.
[0084] 30. The Method according to item 13 above, wherein the
electronic part is a semiconductor part, and wherein the working in
the step (3) is selected from the group consisting of (i) a
grinding of the exposed surface of the semiconductor part, and (ii)
a cutting of the semiconductor part in a thicknesswise direction
thereof from the exposed surface of the semiconductor part.
[0085] 31. The method according to item 30 above, wherein the
semiconductor part is a semiconductor wafer.
[0086] The present invention will now be described in detail.
[0087] The gas-generating, pressure-sensitive adhesive composition
of the present invention is a composition comprising a
pressure-sensitive adhesive (A) and a gas generator compound
(B).
[0088] With respect to the pressure-sensitive adhesive (A) used in
the present invention, there is no particular limitation so long as
the adhesive (A) is an adhesive capable of transmitting
therethrough a radiation selected from the group consisting of an
electromagnetic radiation, an electron radiation and an alpha
radiation. Examples of electromagnetic radiations include a visible
radiation, an ultraviolet radiation, an X-radiation and a
.gamma.-radiation. Examples of the adhesive (A) include rubbery
polymers, such as unsaturated rubbers (e.g., a polyisobutylene and
a butyl rubber) and saturated rubbers (e.g., an
ethylene/propylene(/diene) copolymer rubber, an olefin block
copolymer rubber and an acrylic rubber); acrylic polymers, such as
a copolymer of an acrylic ester and a functional group-containing
monomer; polyethers; polyesters: and polyurethanes. In the present
invention, it is particularly preferred that the pressure sensitive
adhesive (A) contains a photopolymerizable oligomer. It is
preferred that the photopolymerizable oligomer has a polyether
skeleton, a polyester skeleton, an epoxy resin skeleton, a
polycarbonate skeleton, a polybutadiene skeleton, a polyurethane
skeleton or the like, and has at least two functional groups, such
as an acryloyl group (CH.sub.2.dbd.CHO--) and a methacryloyl group
(CH.sub.2.dbd.C(CH.sub.3)CO- --). Specific examples of
photopolymerizable oligomers include oligomers of an epoxy
acrylate, a polyether acrylate, a polyester acrylate, a urethane
acrylate and the like. These oligomers are known as representative
examples of ultraviolet-curable resins, and are generally used for
forming protective coatings for optical fibers or electric
wires.
[0089] The above-mentioned polymers can be used individually or in
combination. With respect to the above-mentioned polymers used as
the pressure-sensitive adhesive (A), the weight average molecular
weight thereof is generally in the range of from 500 to 3,000,000.
The pressure sensitive adhesive (A) may optionally comprise a
crosslinking agent, such as a polyisocyanate or an alkyl etherified
melamine compound, in addition to the polymer used as a base
polymer. In the present invention, the weight average molecular
weight can be measured by gel permeation chromatography (GPC).
[0090] In the present invention, it is preferred that the pressure
sensitive adhesive (A) is curable upon irradiation thereof with the
above-mentioned radiation, especially, an ultraviolet radiation.
The reason for this is as follows. Ultraviolet-curable adhesives
generally have high adhesion strength and, hence, are suitable for
use in attaching a precision electronic part to a substrate. In
addition, upon irradiation with an ultraviolet radiation, the
ultraviolet-curable adhesive is cured, so that the adhesion
strength of the ultraviolet-curable adhesive attached to the
adherend is lowered and, hence, the precision electronic part can
be easily picked up.
[0091] As a specific example of ultraviolet-curable adhesives,
there can be mentioned an adhesive obtained by mixing together:
[0092] (a) at least one base polymer selected from the group
consisting of acrylic polymers (such as copolymers of ethyl
acrylate, butyl acrylate, 2-ethylhexyl acrylate, hydroxymethyl
acrylate and the like), polyethers and polyesters; and
[0093] (b) a photopolymerizable oligomer, such as a urethane
oligomer, an ether oligomer, an ester oligomer, a carbonate
oligomer and a butadiene oligomer; and optionally,
[0094] (c) a photoinitiator, such as 1-hydroxycyolohcxyl phenyl
ketone, isopropylbenzoin ether, benzophenone, xanthone or the like,
and/or
[0095] (d) a crosslinking agent, such as an epoxy-containing
crosslinking agent, an aziridine-containing crosslinking agent or
an isocyanate group-containing crosslinking agent.
[0096] The amounts of the above-mentioned components of the
ultraviolet-curable adhesive can be appropriately selected, taking
into consideration the curing reactivity which the adhesive
exhibits upon irradiation thereof with an ultraviolet irradiation.
The amount of the component (c) is generally in the range of from
0.1 to 20 parts by weight, preferably 1 to 5 parts by weight,
relative to 100 parts by weight of the component (a). The total
amount of the components (b) and (d) is generally in the range of
from 2 to 200 parts by weight, preferably 20 to 150 parts by
weight, more preferably 50 to 100 parts by weight, relative to 100
parts by weight of the component (a).
[0097] Further, the above-mentioned ultraviolet-curable adhesive
may optionally contain:
[0098] (e) an ultraviolet-curable compound other than mentioned
above, such as a polyacrylate of an aliphatic polyol.
[0099] Among the ultraviolet-curable adhesives usable as the
adhesive (A) in the present invention, it is desired to use an
ultraviolet-curable adhesive which, when cured upon irradiation
with an ultraviolet radiation, not only forms therein a
three-dimensional network of pores, but also exhibits a favorable
level of flexibility.
[0100] As mentioned above, the gas-generating, pressure-sensitive
adhesive composition of the present invention contains the gas
generator compound (B). By virtue of the gas generator compound
(B), the gas-generating, pressure-sensitive adhesive composition
has the following advantage when an electronic part (such as a
semiconductor wafer) temporarily attached to a substratum (working
platform) through the gas-generating, pressure-sensitive adhesive
composition is worked, and, then, the gas-generating,
pressure-sensitive adhesive composition is irradiated with the
above-mentioned radiation, the gas generator compound (B) generates
a gas and the gas effuses at an interface between the
gas-generating, pressure-sensitive adhesive composition and the
electronic part to thereby facilitate release of the electronic
part from the gas-generating, pressure-sensitive adhesive
composition. That is, upon the irradiation of the gas-generating,
pressure-sensitive adhesive composition with the radiation, a gas,
such as nitrogen gas, is generated from the inside of the
gas-generating, pressure-sensitive adhesive composition by
decomposition of the gas generator compound (B), and the generated
gas not only reduces the area of contact between the electronic
part and the gas-generating, pressure-sensitive adhesive
composition, but also pressurizes the space between the electronic
part and the gas-generating, pressure-sensitive adhesive, thereby
remarkably improving the releasability of the electronic part from
the gas-generating, pressure-sensitive adhesive composition. Thus,
it becomes possible to release the electronic part (which has been
worked) from the gas-generating, pressure-sensitive adhesive
composition without putting a mechanical or thermal load on the
electronic part. As the gas generator compound (B), it is preferred
to use a compound having an azido group, since an azido group is
decomposed upon absorption of a light radiation (especially an
electromagnetic radiation, such as an ultraviolet radiation) to
release a stable molecular nitrogen gas. That is, the use of an
azido group-containing compound as the gas generator compound (B)
is advantageous in that, upon irradiation of the gas-generating,
pressure-sensitive adhesive composition with the radiation,
nitrogen gas is generated from the inside of the gas-generating,
pressure-sensitive adhesive composition by decomposition of an
azido group contained in the gas generator compound (B), and the
nitrogen gas effuses at an interface between the electronic part
and the gas-generating, pressure-sensitive adhesive composition, so
that the generated nitrogen gas not only reduces the area of
contact between the electronic part and the gas-generating,
pressure-sensitive adhesive composition, but also pressurizes the
space between the electronic part and the gas-generating,
pressure-sensitive adhesive composition, thereby facilitating to
release the electronic part from the gas-generating,
pressure-sensitive adhesive composition. Thus, it becomes possible
to remarkably improve the releasability of the electronic part from
the gas-generating, pressure-sensitive adhesive composition.
[0101] Examples of azido group-containing compounds include sodium
aside. Further examples of azido group-containing compounds include
those which are described in A. M. Helmy et al., "Investigation of
New Energetic Ingredient for Minimum Signature Propellants", 20th
Joint Propulsion Conference (Ohio, 1984). Specific examples of such
compounds include 1,6-diazido-2,5-dinitrazahexane,
1,2-diazido-3-fluorodinitroethoxypropane- ,
3-azido-2,2-dinitropropyl-2,3-diazidopropyl ether, and 3-azido
oxetane. The object of this document is to improve performance of
explosives and, hence, this document enumerates compounds which
contain not only an azido group but also a nitro group. However, in
the present invention, the azido group-containing compounds need
not contain a nitro group. From the viewpoint of uniformly
dispersing the gas generator compound (B) in the gas-generating,
pressure-sensitive adhesive composition, it is preferred to use an
organic compound in a liquid form as the gas generator compound
(B). Further, from the viewpoint of ease in synthesis, safety in
handling and the like, it is especially preferred to use a compound
having an asidomethyl group as the gas generator compound (B).
[0102] Examples of monomers having an azidomethyl group include
AMMO (3-azidomethyl-3-methyloxetane) and BAMO
(3,3-bis(azidomethyl)oxetane). Examples of polymers having an
azidomethyl group include GAP (glycidyl azide polymer). These
azidomethyl group-containing compounds are preferred in that the
compounds have a decomposition temperature of 250.degree. C. or
higher and are easy and safe to handle. The above-mentioned
monomers can also be used not only in the form of homopolymers
thereof but also in the form of copolymers thereof with other
compounds, such as tetrahydrofuran and oxetane compounds other than
mentioned above.
[0103] With respect to the mechanism of the decomposition of the
azidomethyl group-having compound upon irradiation thereof with an
ultraviolet radiation, the present inventors have made a study from
the viewpoint of safety in handling. The results of the study are
disclosed in "Kogyo Kayaku (Industrial Explosives)", Vol. 51, No.
4, pp. 240-245, published by the Industrial Explosives Society,
Japan, 1990.
[0104] In the gas-generating, pressure-sensitive adhesive
composition of the present invention, when a polymer, such as the
above-mentioned GAP, is used as the gas generator compound (B), the
weight average molecular weight of the polymer is generally 10,000
or less, preferably from 500 to 8,000, more preferably from 2,000
to 5,000.
[0105] The ratio of the gas generator compound (B) to the adhesive
(A) is appropriately chosen, taking into consideration the desired
levels of the adhesion strength and releasability, and the
like.
[0106] For example, when the adhesive (A) is the above-mentioned
ultraviolet radiation-curable adhesive containing the component
(a), the ratio of the gas generator compound (B) to the adhesive
(A) is appropriately chosen, taking into consideration the
compatibility of the gas generator compound (B) with the other
component(s), the amount of the gas to be generated and the safety
in handling. Specifically, the amount of the gas generator compound
(B) is generally from 1 to 300 parts by weight, preferably from 5
to 200 parts by weight, more preferably from 10 to 100 parts by
weight, relative to 100 parts by weight of the adhesive (A).
[0107] When the gas-generating, pressure-sensitive adhesive
composition of the present invention is used in the processing of
an electronic part, it is preferred that the gas-generating,
pressure-sensitive adhesive composition is in the form of a tape or
a sheet. When the gas-generating, pressure-sensitive adhesive
composition is in the form of a tape, the gas-generating,
pressure-sensitive adhesive composition can be stored in the form
of a rolled tape. Such a tape or sheet of the gas-generating,
pressure-sensitive adhesive composition is generally provided in
the form of a gas-generating, pressure sensitive hybrid which can
be obtained by applying the gas-generating, pressure-sensitive
adhesive composition of the present invention to an
irradiation-transmitting substratum in the form of a sheet or a
tape, to thereby form a coating on the substratum. The thus
obtained tape or sheet of the gas-generating, pressure-sensitive
adhesive composition has various advantages. One of the advantages
resides in that, in the processing of an electronic part using such
an adhesive composition, it is possible to use the same apparatuses
as used in a conventional method for processing the electronic part
using a conventional adhesive in the form of a tape or a sheet
(such as a conventional ultraviolet radiation-curable adhesive
tape).
[0108] Examples of substrata include rubbers or thermoplastic
resins which transmit an electromagnetic radiation and which are in
the form of a tape (film) or a sheet. Examples of such rubbers and
thermoplastic resins include olefin polymers, such as a
polyethylene, a polypropylene, an ethylene/propylene copolymer, an
ethylene/acrylate copolymer, an ethylene/acrylic acid copolymer, an
ionomer, a poly(1-butene) and an ethylene/vinyl acetate copolymer:
polyesters; polycarbonates; and PMMA (polymethyl methacrylate).
[0109] The thickness of the substratum is preferably from about 10
to about 200 .mu.m. With respect to the thickness of the coating of
the gas-generating, pressure-sensitive adhesive composition formed
on the substratum, the thickness is preferably from 0.005 to 1 mm,
more preferably from 0.01 to 0.5 mm, from the viewpoint of the
effectiveness of the gas generated upon the irradiation. When the
thickness of the coating is larger than 1 mm, disadvantages are
likely to be caused wherein bubbles of the generated gas are
trapped inside the coating of the gas-generating,
pressure-sensitive adhesive composition, so that the generated gas
cannot be effectively used for releasing the electronic part from
the coating of the gas-generating, pressure-sensitive adhesive
composition.
[0110] When the gas-generating, pressure-sensitive adhesive
composition of the present invention is irradiated with the
radiation, the amount of the irradiation varies depending on the
types and amounts of the pressure-sensitive adhesive (A), the gas
generator compound (B) and the photopolymerizable oligomer, and the
like. However, when the radiation is an electron radiation, an
alpha radiation or a gamma radiation, the amount of the irradiation
is generally from 0.5 to 20 Mrad; when the radiation is an
ultraviolet radiation, the amount of the irradiation is generally
from 10 to 3,000 mJ/cm.sup.2, preferably from 30 to 2,000
mJ/cm.sup.2, more preferably from 50 to 500 mJ/cm.sup.2.
[0111] The irradiation time can be adjusted by appropriately
controlling the amount of the irradiation. In general, the
irradiation time is preferably about 10 seconds.
[0112] The gas-generating, pressure-sensitive adhesive composition
of the present invention can be used in various application fields.
For example, in a process for producing a substrate for an
electronic appliance, such as a multilayer substrate (e.g., a film
capacitor), the gas-generating, pressure-sensitive adhesive
composition can be used for protecting the substrate, or
temporarily attaching the substrate to a working platform or the
like. Further, in a process for producing a flexible display, in
which a TFT (thin film transistor) for a picture element is
transferred from a glass substrate to a plastic substrate, the
gas-generating, pressure-sensitive adhesive composition can be used
for temporarily attaching the TFT onto a temporary substratum, or
for masking.
[0113] Hereinbelow, a detailed explanation is made with respect to
the method of the present invention for processing an electronic
part by using a gas-generating, pressure-sensitive adhesive
reagent, such as the gas-generating, pressure-sensitive adhesive
composition of the present invention.
[0114] According to another aspect of the present invention, there
is provided a method for processing an electronic part,
comprising:
[0115] (1) applying a gas-generating, pressure-sensitive adhesive
reagent to a surface of a substratum to provide a gas-generating;
pressure-sensitive adhesive hybrid, wherein the gas-generating,
pressure-sensitive adhesive reagent generates a gas upon
irradiation thereof with a radiation selected from the group
consisting of an electromagnetic radiation, an electron radiation
and an alpha radiation, and wherein the substratum transmits the
irradiation;
[0116] (2) securely attaching one surface of an electronic part
onto a gas-generating, pressure-sensitive adhesive reagent-side
surface of the gas-generating, pressure-sensitive adhesive hybrid,
wherein the other surface of the electronic part is left
exposed;
[0117] (3) working the exposed surface of the electronic part;
[0118] (4) irradiating the gas-generating, pressure-sensitive
adhesive reagent with the radiation through the substratum, to
thereby cause the pressure-sensitive adhesive reagent to generate a
gas, so that the gas effuses at an interface between the
gas-generating, pressure-sensitive adhesive reagent and the
electronic part: and
[0119] (5) detaching the electronic part from the adhesive
hybrid.
[0120] In the present invention, the term electronic part means,
for example, a precision electronic part, a substrate for an
electronic appliance, a semiconductor part or the like. Specific
examples of precision electronic parts include semiconductor
devices, such as a diode, a transistor, a rectifier element, a
thermistor, a varistor and a thyristor; integrated circuits, such
as an IC and an LSI; capacitors, such as a ceramic capacitor, an
aluminum capacitor, a mica capacitor, an organic film capacitor and
a metallized organic capacitor; organic resistors; crystal devices,
such as a crystal oscillator and a crystal filter; and other
electronic parts which are generally used, such as a connector, a
coil, a transformer, a switch, a magnetic head, a polycrystalline
silicon and a TFT (thin film transistor). Specific examples of
substrates for electronic appliances include a sheet of a glass, a
polymer (such as a polyphenylene sulfide or a polymiide) or an
electrode (i.e., an electric conductor, such as silver or copper),
wherein precision electronic parts are mounted on the sheet to form
a circuit. Specific examples of semiconductor parts include
semiconductor wafers, such as a silicon wafer.
[0121] Examples of gas-generating, pressure-sensitive adhesive
reagents used in the method of the present invention include the
gas-generating, pressure-sensitive adhesive composition of the
present invention.
[0122] Examples of gas-generating, pressure-sensitive adhesive
hybrids used in the method of the present invention include an
adhesive sheet or tape which is obtained by forming a coating of
the gas-generating, pressure-sensitive adhesive composition on the
surface of the above-mentioned radiation-transmitting substratum.
Further, in the method of present invention, the substratum may be
a working platform or the like generally used for processing an
electronic part.
[0123] In the method of the present invention, a gas-generating,
pressure-sensitive adhesive polymer which generates a gas upon
irradiation thereof with a radiation selected from the group
consisting of an electromagnetic radiation, an electron radiation
and an alpha radiation can be used alone as a gas-generating,
pressure-sensitive adhesive reagent. Examples of such
gas-generating, pressure-sensitive adhesive polymers include an
azido group-containing polymer having a weight average molecular
weight of 2,300 or more, preferably 10,000 or more, more preferably
from 10,000 to 1,000,000, most preferably from 10,000 to 100,000.
When the weight average molecular weight of the polymer is 10,000
or less, the polymer can be crosslinked using a crosslinking agent,
such as a polyisocyanate. Specific examples of the above-mentioned
polymers include the above-mentioned glycidyl azide polymer (GAP),
a polymer of the above-mentioned AMMO and a polymer of the
above-mentioned BAMO.
[0124] In the case where the electronic part is a semiconductor
part, examples of workings conducted in step (3) of the method of
the present invention include (i) a grinding (such as backgrinding)
of the exposed surface of the semiconductor part, and (ii) a
cutting (such as dicing) of the semiconductor part in a
thicknesswise direction thereof from the exposed surface of the
semiconductor part.
[0125] Examples of electromagnetic radiations used in step (4) of
the method of the present invention include a visible radiation, an
ultraviolet radiation, an X-radiation and a .gamma.-radiation. As
the radiation in step (4), an ultraviolet radiation is especially
preferred.
[0126] With respect to one mode of the method of the present
invention for processing an electronic part, an explanation is made
below with reference to FIGS. 1 to 6.
[0127] First, circular adhesive sheet (2) (i.e., gas-generating,
pressure-sensitive adhesive hybrid which is obtained by applying a
gas-generating, pressure-sensitive adhesive reagent to a surface of
a radiation-transmitting substratum) is secured onto a working
platform or the like using a ring-shaped jig (1) so that a
gas-generating, pressure-sensitive adhesive reagent-side surface of
circular adhesive sheet (2) faces upward (see FIG. 1). Next,
semiconductor wafer (3a) is securely attached to circular adhesive
sheet (2) (see FIG. 2), and semiconductor wafer (3a) is cut into
semiconductor elements (i.e., resultant wafer fragments (3b))
having a desired morphology by using rotary circular blade (4) (see
FIG. 3). Subsequently, the gas-generating, pressure-sensitive
adhesive reagent is irradiated with an ultraviolet radiation
through the radiation-transmitting substratum, to thereby cause the
pressure-sensitive adhesive reagent to generate a gas, so that the
gas effuses at an interface between the gas-generating,
pressure-sensitive adhesive reagent and semiconductor wafer (3a) so
as to thereby facilitate release of wafer fragment (3b) from
circular adhesive sheet (2) (see FIG. 4). Then, wafer fragment (3b)
is picked up using collet (6) (see FIGS. 5 and 6).
[0128] The gas-generating, pressure-sensitive adhesive hybrid as
obtained in step (1) of the method of the present invention can
also be used for transporting and mounting electronic parts by the
method disclosed in Unexamined Japanese Patent Application
Laid-Open Specification No. Hei 11-334785.
BEST MODE FOR CARRYING OUT THE INVENTION
[0129] Hereinbelow, the present invention will be described in more
detail with reference to the following Examples and Comparative
Example; however, they should not be construed as limiting the
scope of the present invention.
[0130] In the following Examples and Comparative Example, the
releasability of a thin glass plate from a coating of a
pressure-sensitive adhesive is evaluated by a method in which a
thin glass plate having a thickness of about 0.15 mm is attached
onto a coating of a pressure-sensitive adhesive and, then the glass
plate is released from the coating, wherein the thin glass plate is
used as a substitute for an electronic part.
EXAMPLE 1
In which a glycidyl azide polymer (GAP), which is a polymer having
an azido group, was solely used as a gas generator compound
[0131] A glycidyl aside polymer (GAP) having a weight average
molecular weight of about 2,500 and having OH groups at both
terminals thereof was synthesized in accordance with a method
disclosed in U.S. Pat. No. 4,268,450. The GAP was spread over a
substratum to form a thin coating having a thickness of about 3 mm.
On the resultant GAP coating was placed a cover glass (for
microscope observation) (width and length: 18 mm.times.18 mm,
thickness: about 0.15 mm). The GAP coating was irradiated with an
ultraviolet radiation (115 V, 60 Hz, 0.16 A) by means of a UV lamp
(MODEL UVGL-58, manufactured and sold by San Gabriel. U.S.A.) for
about 10 minutes, wherein the irradiation was conducted from a
position about 1 cm above the glass plate. As a result, a number of
nitrogen gas bubbles generated from the GAP coating were observed
at an interface between the glass plate and the GAP coating. Thus,
it was confirmed that nitrogen gas generated from the GAP coating
had reduced an area of contact between the glass plate and the GAP
coating.
EXAMPLE 2
In which a glycidyl azide polymer (GAP), which is a polymer having
an azido group, was used in combination with a compound serving as
a crosslinking agent
[0132] 100 g of a glycidyl azide polymer (GAP) (having a weight
average molecular weight of about 2,500 and having OH groups at
both terminals thereof) synthesized in substantially the same
manner as in Example 1 was placed in a mold having its surface
covered with a Teflon sheet. To the GAP were added and mixed well
3.6 g of IPDI (isophorone diisocyanate) (VESTANATA IPDI,
manufactured and sold by Degussa-Hals Japan Co., Ltd., Japan) and
8.7 g of TPA-100 (one product of DURANATE series, manufactured and
sold by ASAHI KASRI Corporation, Japan) which is a trifunctional
isocyanate and an adduct of hexamethylene diisocyanate (which IPDI
and TPA-100 were used as a crosslinking agent), thereby obtaining a
gas-generating, pressure-sensitive adhesive composition. The
obtained gas-generating, pressure-sensitive adhesive composition
was spread over the Teflon sheet in the mold to form a thin coating
having a thickness of about 2.5 mm. The gas-generating,
pressure-sensitive adhesive composition coating formed on the
Teflon sheet was heated at 60.degree. C. for about 4 days to effect
a curing reaction, thereby obtaining a cured polymer coating formed
on the Teflon sheet. On the cured polymer coating was placed the
same glass plate as used in Example 1 so as to adhere the glass
plate to the cured polymer coating. Then, the cured polymer coating
having the glass plate adhered thereto was irradiated with an
ultraviolet radiation in substantially the same manner as in
Example 1. As a result, it was observed that a gas was generated
from the cured polymer coating, and the gas effused at an interface
between the cured polymer coating and the glass plate, so that
several minutes later the glass plate was partially released from
the cured polymer coating. The glass plate could be easily detached
from the cured polymer coating by hand.
[0133] In this Example 2, as mentioned above, the preparation of
the above-mentioned gas-generating, adhesive composition was
performed by mixing together well the above-mentioned GAP and the
crosslinking agent in a mold having its surface covered with a
Teflon sheet for preventing the gas-generating, adhesive
composition from adhering to the mold. After the irradiation with
the ultraviolet radiation, it was observed that, due to the gas
generated from the cured polymer coating, partial release occurred
also at the interface between the Teflon sheet and the cured
polymer coating.
[0134] In the cured polymer coating, about ten and several gas
bubbles were generated per 1 cm.sup.2 (most of the bubbles had a
diameter of from 1 to 2 mm). It was confirmed that by virtue of the
high uniformity of the dispersion of the organic azide contained in
the cured polymer coating, the gas generated in the cured polymer
coating is less likely to be trapped within the cured polymer
coating and is more likely to effuse at the interface between the
cured polymer coating and the glass plate and the interface between
the cured polymer coating and the Teflon sheet, thereby
facilitating release of the glass plate and Teflon sheet from the
cured polymer coating.
[0135] From the results of Example 2, it was found that, when the
cured polymer coating has a thickness of more than 1 mm, bubbles
(namely, the gas trapped in the cured polymer coating) are likely
to be formed within the cured polymer coating. Therefore, it was
confirmed that, for more effectively utilizing the generated gas in
order to facilitate the release of the glass plate and Teflon sheet
from the cured polymer coating, the cured polymer coating is
desired to have a thickness of 1 mm or less.
EXAMPLE 3
In which a glycidyl azide polymer (GAP), which is a polymer having
an azido group, was used in combination with an ultraviolet-curable
resin
[0136] A glycidyl azide polymer (GAP) having a weight average
molecular weight of about 2,500 and having OH groups at both
terminals thereof was synthesized in the same manner as in Example
1. The obtained GAP and an APR resin (photosensitive resin
manufactured and sold by ASAHI KASEI Corporation, Japan, which is a
polyurethane resin modified with a carboxylic acid) were mixed in a
weight ratio of 1:1 to obtain a gas-generating, pressue-sensitive
adhesive composition. The obtained gas-generating,
pressure-sensitive adhesive composition was spread over a
substratum to form a thin coating having a thickness of about 2.5
mm. On the gas-generating, pressure-sensitive adhesive composition
coating was placed the same glass plate as used in Example 1 so as
to adhere the glass plate to the gas-generating, pressure-sensitive
adhesive composition coating. Then, the gas-generating,
pressure-sensitive adhesive composition coating having the glass
plate adhered thereto was irradiated with an ultraviolet radiation
in substantially the same manner as in Example 1 so as to cure the
gas-generating, pressure-sensitive adhesive composition coating. As
a result, it was observed that a gas was generated from the
gas-generating, pressure-sensitive adhesive composition coating
during and after the curing thereof. Then, the cured coating was
exposed to the sunlight (which contains an ultraviolet radiation
having a high intensity as compared to that used in Example 1) for
about 30 minutes. As a result, it was observed that the glass plate
was partially released from the cured coating. From the cured
coating, the glass plate could be easily detached intact by
hand.
COMPARATIVE EXAMPLE 1
[0137] Substantially the same procedure as in Example 3 was
repeated, except that PPG (polypropylene glycol) was used instead
of the GAP, With respect to the coating having the glass plate
adhered thereto, even after the curing of the coating and the
exposure of the coating to the sunlight, the glass plate remained
adhered to the coating. When it was attempted to detach the glass
plate from the cured coating, the glass plate was broken.
INDUSTRIAL APPLICABILITY
[0138] In the gas-generating, pressure-sensitive adhesive
composition of the present invention, the gas generator compound
(B) is operably combined with the pressure-sensitive adhesive (A),
so that, in operation, when the gas-generating, pressure-sensitive
adhesive composition which is adhered to an adherend is irradiated
with a radiation, the gas generator compound (B) generates a gas
and the gas effuses at an interface between the gas-generating,
pressure-sensitive adhesive composition and the adherend to thereby
facilitate release of the adherend from the gas-generating,
pressure-sensitive adhesive composition. Therefore, in the working
(e.g., grinding or cutting) of an electronic part, such as a
precision electronic part, a substrate for an electronic appliance,
or a semiconductor part (e.g., a semiconductor wafer), when the
gas-generating, pressure-sensitive adhesive composition of the
present invention is used as an adhesive for temporarily attaching
the electronic part to a substratum (working platform) or the like,
various advantages can be obtained. That is, it is possible not
only to attach the electronic part securely to the substratum or
the like, but also to remarkably improve the releasability of the
electronic part from the gas-generating, pressure-sensitive
adhesive composition upon irradiation of the composition with a
radiation (which is generally applied to in the processing of the
electronic part), so that, after the working (e.g., grinding or
cutting) of the electronic part, the electronic part can be easily
released from the gas-generating, pressure-sensitive adhesive
composition without putting a high load to the electronic part.
Accordingly, by the use of the gas-generating, pressure-sensitive
adhesive composition of the present invention, the processing of an
electronic part can be efficiently conducted without causing
breakage of the electronic part.
[0139] In the method of the present invention for processing an
electronic part, such as a precision electronic part, a substrate
for an electronic appliance, or a semiconductor part (e.g., a
semiconductor wafer), which method uses a specific gas-generating,
pressure-sensitive adhesive reagent, such as the above-mentioned
gas-generating, pressure-sensitive adhesive composition, an
appropriate type of the gas-generating, pressure-sensitive adhesive
reagent can be chosen, taking into consideration the type of the
electronic part to be processed, the conditions for processing and
the like. Examples of gas-generating, pressure-sensitive adhesive
reagents include: (i) a gas-generating, pressure-sensitive polymer
which generates a gas upon irradiation thereof with a radiation
selected from the group consisting of an electromagnetic radiation,
an electron radiation and an alpha radiation (see Example 1); (ii)
a gas-generating, pressure-sensitive composition comprising the
adhesive (A) and crosslinking agents (see Example 2); and (iii) a
gas-generating, pressure-sensitive composition comprising the
adhesive (A) and a polymer curable upon irradiation thereof with a
radiation, such as an ultraviolet radiation.
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