U.S. patent application number 09/773800 was filed with the patent office on 2002-01-17 for die attach adhesives for use in microelectronic devices.
Invention is credited to Herr, Donald E., Schultz, Rose Ann.
Application Number | 20020007042 09/773800 |
Document ID | / |
Family ID | 26784018 |
Filed Date | 2002-01-17 |
United States Patent
Application |
20020007042 |
Kind Code |
A1 |
Herr, Donald E. ; et
al. |
January 17, 2002 |
Die attach adhesives for use in microelectronic devices
Abstract
A thermoplastic or thermosetting adhesive for bonding an
electronic component to a substrate in which the adhesive is cured
in situ from a curable composition comprises one or more poly- or
mono-functional maleimide compounds, or one or more poly- or
mono-functional vinyl compounds other than maleimide compounds, or
a combination of maleimide and vinyl compounds, a curing initiator
and optionally, one or more fillers.
Inventors: |
Herr, Donald E.;
(Doylestown, PA) ; Schultz, Rose Ann; (Westford,
MA) |
Correspondence
Address: |
JANE GENNARO
c/o NATIONAL STARCH & CHEMICAL CO.
10 FINDERNE AVE
BRIDGEWATER
NJ
08807
US
|
Family ID: |
26784018 |
Appl. No.: |
09/773800 |
Filed: |
February 1, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09773800 |
Feb 1, 2001 |
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09336245 |
Jun 18, 1999 |
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6265530 |
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60091492 |
Jul 2, 1998 |
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Current U.S.
Class: |
528/322 ;
257/E21.514; 525/182; 525/185; 525/279; 525/282; 525/422; 526/262;
528/117; 528/172; 528/211; 528/248; 528/253 |
Current CPC
Class: |
H01L 24/29 20130101;
C08F 290/06 20130101; H01L 2224/2929 20130101; H01L 2924/01042
20130101; H01L 2924/15747 20130101; H01L 2224/8319 20130101; H01L
2224/29364 20130101; H01L 2924/01016 20130101; H01L 2224/29386
20130101; H01L 2924/01046 20130101; H01L 2924/01005 20130101; H01L
2924/14 20130101; H01L 2924/00013 20130101; H01L 2924/01011
20130101; H01L 2924/01045 20130101; H01L 2924/01075 20130101; C08G
18/282 20130101; H01L 24/83 20130101; H01L 2224/2919 20130101; H01L
2224/29339 20130101; H01L 2224/29344 20130101; C09J 183/10
20130101; H01L 2924/01024 20130101; H01L 2924/01079 20130101; H01L
2924/01029 20130101; H01L 2924/0665 20130101; C08G 77/42 20130101;
C09J 4/06 20130101; H01L 2924/01082 20130101; H01L 2924/0781
20130101; H01L 2224/29347 20130101; H01L 2924/01078 20130101; H01L
2924/01023 20130101; C08F 290/065 20130101; C08G 18/75 20130101;
H01L 2924/01077 20130101; H01L 2224/29 20130101; H01L 2924/01006
20130101; H01L 2924/10253 20130101; H01L 2924/01004 20130101; H01L
2924/01033 20130101; H01L 2924/01047 20130101; H01L 2224/29369
20130101; H01L 2224/838 20130101; H01L 2924/01013 20130101; H01L
2924/01019 20130101; H01L 2924/01025 20130101; H01L 2924/01015
20130101; H01L 2924/0105 20130101; C08G 18/2875 20130101; C09J 4/06
20130101; C08F 290/06 20130101; H01L 2924/0665 20130101; H01L
2924/00 20130101; H01L 2224/2929 20130101; H01L 2924/00014
20130101; H01L 2224/29339 20130101; H01L 2924/00014 20130101; H01L
2224/29347 20130101; H01L 2924/00014 20130101; H01L 2224/29344
20130101; H01L 2924/00014 20130101; H01L 2224/29364 20130101; H01L
2924/00014 20130101; H01L 2224/29369 20130101; H01L 2924/00014
20130101; H01L 2224/29386 20130101; H01L 2924/05432 20130101; H01L
2924/00014 20130101; H01L 2224/29386 20130101; H01L 2924/05442
20130101; H01L 2924/00014 20130101; H01L 2924/3512 20130101; H01L
2924/00 20130101; H01L 2924/00013 20130101; H01L 2224/29099
20130101; H01L 2924/00013 20130101; H01L 2224/29199 20130101; H01L
2924/00013 20130101; H01L 2224/29299 20130101; H01L 2924/00013
20130101; H01L 2224/2929 20130101; H01L 2924/10253 20130101; H01L
2924/00 20130101; H01L 2924/15747 20130101; H01L 2924/00
20130101 |
Class at
Publication: |
528/322 ;
528/117; 528/211; 528/172; 528/253; 528/248; 526/262; 525/182;
525/185; 525/279; 525/282; 525/422 |
International
Class: |
C08G 073/12 |
Claims
What is claimed is:
1. A curable adhesive composition for use in bonding an electronic
component to a substrate comprising a maleimide compound and a
curing initiator selected from the group consisting of a
free-radical initiator, a photoinitiator, and a combination of
those, the maleimide compound having the formula
[M-X.sub.m].sub.n-Q in which m is 0 or 1 and n is 1 to 6, and (a) M
is a maleimide moiety having the structure: 34in which R.sup.1is H
or an alkyl group having 1 to 5 carbon atoms; (b) X is an aromatic
group selected from the group of aromatic groups having the
structures: 35and (c) Q is a linear or branched chain alkyl,
alkyloxy, alkyl amine, alkyl sulfide, alkylene, alkyleneoxy,
alkylene amine, alkylene sulfide, aryl, aryloxy, or aryl sulfide
species, which may contain saturated or unsaturated cyclic or
heterocyclic substituents pendant from the chain or as part of the
chain, and in which any heteratom present may or may not be
directly attached to X.
2. The curable adhesive composition according to claim 1 in which Q
is a linear or branched chain alkyl, alkyloxy, alkylene, or
alkyleneoxy species, which may contain saturated or unsaturated
cyclic or heterocyclic substituents pendant from the chain or as
part of the chain.
3. The curable adhesive composition according to claim 2 in which Q
is a linear or branched chain alkyl species, which may contain
saturated or unsaturated cyclic or heterocyclic substituents
pendant from the chain or as part of the chain.
4. The curable adhesive composition according to claim 1 in which Q
is a urethane having the structure: 36in which each R.sup.2
independently is an alkyl, aryl, or arylalkyl group having 1 to 18
carbon atoms; R.sup.3 is an alkyl or alkyloxy chain having up to
100 atoms in the chain, which chain may contain aryl substituents;
X is O, S, N, or P; and v is 0 to 50.
5. The curable adhesive composition according to claim 1 in which Q
is an ester having the structure: 37in which R.sup.3 is an alkyl or
alkyloxy chain having up to 100 atoms in the chain, which chain may
contain aryl substituents.
6. The curable adhesive composition according to claim 1 in which Q
is an ester having the structure: 38in which p is 1 to 100, and
each R.sup.3 can independently be an alkyl or alkyloxy chain having
up to 100 atoms in the chain, which chain may contain aryl
substituents; or each R.sup.3 can independently be a siloxane
having the structure--(CR.sup.1.sub.2).sub.e--
-[SiR.sup.4.sub.2--O].sub.f--SiR.sup.4.sub.2--(CR.sup.1.sub.2).sub.g--
in which the R.sup.1 substituent independently for each position is
H or an alkyl group having 1 to 5 carbon atoms, the R.sup.4
substituent independently for each position is an alkyl group
having 1 to 5 carbon atoms or an aryl group, e and g are
independently 1 to 10, and f is 1 to 50.
7. The curable adhesive composition according to claim 1 in which Q
is an ester having the structure: 39in which p is 1 to 100, and
each R.sup.3 can independently be an alkyl or alkyloxy chain having
up to 100 atoms in the chain, which chain may contain aryl
substituents; or each R.sup.3 can independently be a siloxane
having the structure--(CR.sup.1.sub.2).sub.e--
-[SiR.sup.4.sub.2--O].sub.f--SiR.sup.4.sub.2--(CR.sup.1.sub.2).sub.g--
in which the R.sup.1 substituent independently for each position is
H or an alkyl group having 1 to 5 carbon atoms, the R.sup.4
substituent independently for each position is an alkyl group
having 1 to 5 carbon atoms or an aryl group, e and g are
independently 1 to 10, and f is 1 to 50.
8. A curable adhesive composition comprising a maleimide compound
and a curing initiator selected from the group consisting of a
free-radical initiator, a photoinitiator, and a combination of
those, the maleimide compound having the formula
[M-Z.sub.m].sub.n-K in which m is 0 or 1 and n is 1-6, and (a) M is
a maleimide moiety having the structure 40in which R.sup.1 is H or
an alkyl having 1 to 5 carbon atoms; (b) K is an aromatic group
selected from group of aromatic groups having the structures: 41in
which p is 1 to 100; in which p is 1 to 100; in which R.sup.5,
R.sup.6, and R.sup.7 are a linear or branched chain alkyl,
alkyloxy, alkyl amine, alkyl sulfide, alkylene, alkyleneoxy,
alkylene amine, alkylene sulfide, aryl, aryloxy, or aryl sulfide
species, which may contain saturated or unsaturated cyclic or
heterocyclic substituents pendant from the chain or as part of the
backbone in the chain, and in which any heteratom present may or
may not be directly attached to the aromatic ring; or R.sup.5,
R.sup.6, and R.sup.7 are a siloxane having the structure
--(CR.sup.1.sub.2).sub.e--[SiR.sup.4.sub.2--O].sub.f--SiR.sup.4-
.sub.2--(CH.sub.3).sub.g-- in which the R.sup.1 substituent is H or
an alkyl group having 1 to 5 carbon atoms and the R.sup.4
substituent independently for each position is an alkyl group
having 1 to 5 carbon atoms or an aryl group, and e is 1 to 10 and f
is 1 to 50; 42and (c) Z is a linear or branched chain alkyl,
alkyloxy, alkyl amine, alkyl sulfide, alkylene, alkyleneoxy,
alkylene amine, alkylene sulfide, aryl, aryloxy, or aryl sulfide
species, which may contain saturated or unsaturated cyclic or
heterocyclic substituents pendant from the chain or as part of the
chain, and in which any heteratom present may or may not be
directly attached to K.
9. The curable adhesive composition according to claim 8 in which Z
is a linear or branched chain alkyl, alkyloxy, alkylene, or
alkyleneoxy species, which may contain saturated or unsaturated
cyclic or heterocyclic substituents pendant from the chain or as
part of the chain.
10. The curable adhesive composition according to claim 8 in which
Z is a linear or branched chain alkyl species, which may contain
saturated or unsaturated cyclic or heterocyclic substituents
pendant from the chain or as part of the chain.
11. The curable adhesive composition according to claim 8 in which
Z is a urethane having the structure: 43in which each R.sup.2
independently is an alkyl, aryl, or arylalkyl group having 1 to 18
carbon atoms; R.sup.3 is an alkyl or alkyloxy chain having up to
100 atoms in the chain, which chain may contain aryl substituents;
X is O, S, N, or P; and v is 0 to 50.
12. The curable adhesive composition according to claim 8 in which
Z is an ester having the structure: 44in which R.sup.3 is an alkyl
or alkyloxy chain having up to 100 atoms in the chain, which chain
may contain aryl substituents.
13. The curable adhesive composition according to claim 8 in which
Z is an ester having the structure: 45in which p is 1 to 100, and
each R.sup.3 can independently be an alkyl or alkyloxy chain having
up to 100 atoms in the chain, which chain may contain aryl
substituents; or each R.sup.3 can independently be a siloxane
having the structure--(CR.sup.1.sub.2).sub.e--
-[SiR.sup.4.sub.2--O].sub.f--SiR.sup.4.sub.2--(CR.sup.1.sub.2).sub.g--in
which the R.sup.1substituent independently for each position is H
or an alkyl group having 1 to 5 carbon atoms, the R.sup.4
substituent independently for each position is an alkyl group
having 1 to 5 carbon atoms or an aryl group, e and g are
independently 1 to 10, and f is 1 to 50.
14. The curable adhesive composition according to claim 8 in which
Z is an ester having the structure: 46in which p is 1 to 100, and
each R.sup.3 can independently be an alkyl or alkyloxy chain having
up to 100 atoms in the chain, which chain may contain aryl
substituents; or each R.sup.3 can independently be a siloxane
having the structure--(CR.sup.1.sub.2).sub.e--
-[SiR.sup.4.sub.2--O].sub.f--SiR.sup.4.sub.2--(CR.sup.1.sub.2).sub.g--in
which the R.sup.1substituent independently for each position is H
or an alkyl group having 1 to 5 carbon atoms, the R.sup.4
substituent independently for each position is an alkyl group
having 1 to 5 carbon atoms or an aryl group, e and g are
independently 1 to 10, and f is 1 to 50.
15. The curable adhesive composition according to any one of claims
8 to 14 in which K is 47in which p is 1 to 100.
16. The curable adhesive composition according to any one of claims
8 to 14 in which K is 48in which R.sup.5, R.sup.6, and R.sup.7 are
a linear or branched chain alkyl, alkyloxy, alkyl amine, alkyl
sulfide, alkylene, alkyleneoxy, alkylene amine, alkylene sulfide,
aryl, aryloxy, or aryl sulfide species, which may contain saturated
or unsaturated cyclic or heterocyclic substituents pendant from the
chain or as part of the chain, and in which any heteroatom present
may or may not be directly attached to the aromatic ring.
17. The curable adhesive composition according to any one of claims
8 to 14 in which K is 49
18. A curable adhesive composition comprising a vinyl compound and
a curing initiator selected from the group consisting of a
free-radical initiator, a photoinitiator, and a combination of
those, the vinyl compound having the formula 50in which m is 0 or 1
and n is 1-6; and (a) R.sup.1 and R.sup.2 are H or an alkyl group
having 1 to 5 carbon atoms, or together form a 5 to 9 membered ring
with the carbons forming the vinyl group; (b) B is C, S, N, O,
C(O), C(O)NH or C(O)N(R.sup.8), in which R.sup.8 is an alkyl group
having 1 to 5 carbon atoms; (c) X is an aromatic group selected
from the group of aromatic groups having the structures: 51(d) Q is
a linear or branched chain alkyl, alkyloxy, alkyl amine, alkyl
sulfide, alkylene, alkyleneoxy, alkylene amine, alkylene sulfide,
aryl, aryloxy, or aryl sulfide species, which may contain saturated
or unsaturated cyclic or heterocyclic substituents pendant from the
chain or as part of the chain, and in which any heteratom present
may or may not be directly attached to X.
19. The curable adhesive composition according to claim 18 in which
Q is a linear or branched chain alkyl, alkyloxy, alkylene, or
alkyleneoxy species, which may contain saturated or unsaturated
cyclic or heterocyclic substituents pendant from the chain or as
part of the chain.
20. The curable adhesive composition according to claim 19 in which
Q is a linear or branched chain alkyl species, which may contain
saturated or unsaturated cyclic or heterocyclic substituents
pendant from the chain or as part of the chain.
21. The curable adhesive composition according to claim 18 in which
Q is a urethane having the structure: 52in which each R.sup.2
independently is an alkyl, aryl, or arylalkyl group having 1 to 18
carbon atoms; R.sup.3 is an alkyl or alkyloxy chain having up to
100 atoms in the chain, which chain may contain aryl substituents;
X is O, S, N, or P; and v is 0 to 50.
22. The curable adhesive composition according to claim 18 in which
Q is an ester having the structure: 53in which R.sup.3 is an alkyl
or alkyloxy chain having up to 100 atoms in the chain, which chain
may contain aryl substituents.
23. The curable adhesive composition according to claim 18 in which
Q is an ester having the structure: 54in which p is 1 to 100, and
each R.sup.3 can independently be an alkyl or alkyloxy chain having
up to 100 atoms in the chain, which chain may contain aryl
substituents; or each R.sup.3 can independently be a siloxane
having the
structure--(CR.sup.1.sub.2).sub.e--[SiR.sup.4.sub.2--O].sub.f--SiR.sup.4.-
sub.2--(CR.sup.1.sub.2).sub.g--in which the R.sup.1 substituent
independently for each position is H or an alkyl group having 1 to
5 carbon atoms, the R.sup.4 substituent independently for each
position is an alkyl group having 1 to 5 carbon atoms or an aryl
group, e and g are independently 1 to 10, and f is 1 to 50.
24. The curable adhesive composition according to claim 18 in which
Q is an ester having the structure: 55in which p is 1 to 100, and
each R.sup.3 can independently be an alkyl or alkyloxy chain having
up to 100 atoms in the chain, which chain may contain aryl
substituents; or each R.sup.3 can independently be a siloxane
having the
structure--(CR.sup.1.sub.2).sub.e--[SiR.sup.4.sub.2--O].sub.f--SiR.sup.4.-
sub.2--(CR.sup.1.sub.2).sub.g--in which the R.sup.1 substituent
independently for each position is H or an alkyl group having 1 to
5 carbon atoms, the R.sup.4 substituent independently for each
position is an alkyl group having 1 to 5 carbon atoms or an aryl
group, e and g are independently 1 to 10, and f is 1 to 50.
25. A curable adhesive composition comprising a vinyl compound and
a curing initiator selected from the group consisting of a
free-radical initiator, a photoinitiator, and a combination of
those, the vinyl compound having the formula 56in which m is 0 or 1
and n is 1-6; and (a) R.sup.1and R.sup.2 are H or an alkyl group
having 1 to 5 carbon atoms, or together form a 5 to 9 membered ring
with the carbons forming the vinyl group; (b) B is C, S, N, O,
C(O), C(O)NH or C(O)N(R.sup.8), in which R.sup.8 is an alkyl group
having 1 to 5 carbon atoms; (c) K is an aromatic group selected
from the group of aromatic groups having the structures: 57in which
p is 1 to 100; in which p is 1 to 100; in which R.sup.5, R.sup.6,
and R.sup.7 are a linear or branched chain alkyl, alkyloxy, alkyl
amine, alkyl sulfide, alkylene, alkyleneoxy, alkylene amine,
alkylene sulfide, aryl, aryloxy, or aryl sulfide species, which may
contain saturated or unsaturated cyclic or heterocyclic
substituents pendant from the chain or as part of the backbone in
the chain, and in which any heteratom present may or may not be
directly attached to the aromatic ring; or R.sup.5, R.sup.6, and
R.sup.7are a siloxane having the structure
--(CR.sup.1.sub.2).sub.e--[SiR.sup.4.sub.2--O].sub.f--SiR.sup.4-
.sub.2--(CH.sub.3).sub.g--in which the R.sup.1substituent is H or
an alkyl group having 1 to 5 carbon atoms and the R.sup.4
substituent independently for each position is an alkyl group
having 1 to 5 carbon atoms or an aryl group, and e is 1 to 10 and f
is 1 to 50; 58and (d) Z is a linear or branched chain alkyl,
alkyloxy, alkyl amine, alkyl sulfide, alkylene, alkyleneoxy,
alkylene amine, alkylene sulfide, aryl, aryloxy, or aryl sulfide
species, which may contain saturated or unsaturated cyclic or
heterocyclic substituents pendant from the chain or as part of the
chain, and in which any heteratom present may or may not be
directly attached to X.
26. The curable adhesive composition according to claim 25 in which
Z is a linear or branched chain alkyl, alkyloxy, alkylene, or
alkyleneoxy species, which may contain saturated or unsaturated
cyclic or heterocyclic substituents pendant from the chain or as
part of the chain.
27. The curable adhesive composition according to claim 25 in which
Z is a linear or branched chain alkyl species, which may contain
saturated or unsaturated cyclic or heterocyclic substituents
pendant from the chain or as part of the chain.
28. The curable adhesive composition according to claim 25 in which
Z is a urethane having the structure: 59in which each R.sup.2
independently is an alkyl, aryl, or arylalkyl group having 1 to 18
carbon atoms; R.sup.3 is an alkyl or alkyloxy chain having up to
100 atoms in the chain, which chain may contain aryl substituents;
X is O, S, N, or P; and v is 0 to 50.
29. The curable adhesive composition according to claim 25 in which
Z is an ester having the structure: 60in which R.sup.3 is an alkyl
or alkyloxy chain having up to 100 atoms in the chain, which chain
may contain aryl substituents.
30. The curable adhesive composition according to claim 25 in which
Z is an ester having the structure: 61in which p is 1 to 100, and
each R.sup.3 can independently be an alkyl or alkyloxy chain having
up to 100 atoms in the chain, which chain may contain aryl
substituents; or each R.sup.3 can independently be a siloxane
having the
structure--(CR.sup.1.sub.2).sub.e--[SiR.sup.4.sub.2--O].sub.f--SiR.sup.4.-
sub.2--(CR.sup.1.sub.2).sub.g--in which the R.sup.1 substituent
independently for each position is H or an alkyl group having 1 to
5 carbon atoms, the R.sup.4 substituent independently for each
position is an alkyl group having 1 to 5 carbon atoms or an aryl
group, e and g are independently 1 to 10, and f is 1 to 50.
31. The curable adhesive composition according to claim 25 in which
Z is an ester having the structure: 62in which p is 1 to 100, and
each R.sup.3 can independently be an alkyl or alkyloxy chain having
up to 100 atoms in the chain, which chain may contain aryl
substituents; or each R.sup.3 can independently be a siloxane
having the
structure--(CR.sup.1.sub.2).sub.e--[SiR.sup.42--O].sub.f--SiR.sup.4.sub.2-
--(CR.sup.1.sub.2).sub.g--in which the R.sup.1 substituent
independently for each position is H or an alkyl group having 1 to
5 carbon atoms, the R.sup.4 substituent independently for each
position is an alkyl group having 1 to 5 carbon atoms or an aryl
group, e and g are independently 1 to 10, and f is 1 to 50.
32. The curable adhesive composition according to any one of claims
25 to 31 in which K is 63when p is 1 to 100.
33. The curable adhesive composition according to any one of claims
25 to 31 in which K is 64in which R.sup.5, R.sup.6, and R.sup.7 are
a linear or branched chain alkyl, alkyloxy, alkyl amine, alkyl
sulfide, alkylene, alkyleneoxy, alkylene amine, alkylene sulfide,
aryl, aryloxy, or aryl sulfide species, which may contain saturated
or unsaturated cyclic or heterocyclic substituents pendant from the
chain or as part of the chain, and in which any heteroatom present
may or may not be directly attached to the aromatic ring.
34. The curable adhesive composition according to any one of claims
25 to 31 in which K is 65
35. A curable adhesive composition comprising a maleimide compound
as described in any one of claims 1 to 17 and a vinyl compound as
described in any one of claims 18 to 34, and a curing
initiator.
36. A curable adhesive composition comprising a maleimide compound
as described in any one of claims 1 to 17, or a vinyl compound as
described in any one of claims 18 to 34, or a combination of a
maleimide compound as described in any one of claims 1 to 17 and a
vinyl compound as described in any one of claims 18 to 34, and an
anionic or cationic curing initiator.
37. An electronic assembly comprising an electronic component
bonded to a substrate with a cured adhesive composition prepared
from a composition according to any one of the preceding claims.
Description
[0001] The priority of provisional application 60/091,492, filed
Jul. 20, 1998, is claimed under 35 USC 119 (e).
FIELD OF THE INVENTION
[0002] This invention relates to compositions that are suitable for
use as adhesives in microelectronic devices or semiconductor
packages.
BACKGROUND OF THE INVENTION
[0003] Adhesive compositions, particularly conductive adhesives,
are used for a variety of purposes in the fabrication and assembly
of semiconductor packages and microelectronic devices. The more
prominent uses are the bonding of integrated circuit chips to lead
frames or other substrates, and the bonding of circuit packages or
assemblies to printed wire boards.
[0004] The requirements for conductive adhesives in electronic
packaging are that they have good mechanical strength, curing
properties that do not affect the component or the carrier, and
thixotropic properties compatible with existing application
equipment currently used in the industry.
[0005] Another important aspect of an adhesive bonding or
interconnection technology is the ability to rework the bond. For
single chip packaging involving high volume commodity products, a
failed chip can be discarded without significant loss. However, it
becomes expensive to discard multi-chip packages with only one
failed chip; consequently, the ability to rework the failed chip
would be a manufacturing advantage. Today, one of the primary
thrusts within the semiconductor industry is to develop adhesives
that will meet all the requirements for adhesive strength and
flexibility, but that will also be reworkable, that is, will be
capable of being removed without destroying the substrate.
SUMMARY OF THE INVENTION
[0006] This invention is an adhesive composition for use in
electronic devices that comprises one or more mono- or
polyfunctional maleimide compounds, or one or more mono- or
polyfunctional vinyl compounds other than maleimide compounds, or a
combination of maleimide and vinyl compounds, a curing initiator,
and optionally, one or more fillers. The composition can be
designed to be reworkable.
[0007] In another embodiment, this invention is the cured adhesive
that results from the just described curable adhesive
composition.
[0008] In another embodiment, this invention is a microelectronic
assembly comprising an electronic component bonded to a substrate
with a cured adhesive composition prepared from a composition
comprising one or more mono- or polyfunctional maleimide compounds,
or one or more mono- or polyfunctional vinyl compounds, or a
combination of maleimide and vinyl compounds, a curing initiator,
and optionally one or more fillers.
DETAILED DESCRIPTION OF THE INVENTION
[0009] The maleimide and vinyl compounds used in the adhesive
compositions of this invention are curable compounds, meaning that
they are capable of polymerization, with or without crosslinking.
As used in this specification, to cure will mean to polymerize,
with or without crosslinking. Cross-linking, as is understood in
the art, is the attachment of two polymer chains by bridges of an
element, a molecular group, or a compound, and in general will take
place upon heating. As cross-linking density is increased, the
properties of a material can be changed from thermoplastic to
thermosetting.
[0010] It is possible to prepare polymers of a wide range of
cross-link density by the judicious choice and amount of mono- or
polyfunctional compounds. The greater proportion of polyfunctional
compounds reacted, the greater the cross-link density. If
thermoplastic properties are desired, the adhesive compositions can
be prepared from mono-functional compounds to limit the cross-link
density. A minor amount of poly-functional compounds can be added
to provide some cross-linking and strength to the composition,
provided the amount of poly-functional compounds is limited to an
amount that does not diminish the desired thermoplastic properties.
Within these parameters, the strength and elasticity of individual
adhesives can be tailored to a particular end-use application.
[0011] In those cases where it is necessary to rework the assembly
and thermoplastic materials are used, the electronic component can
be pried off the substrate, and any residue adhesive can be heated
until it softens and is easily removed.
[0012] The cross-link density can also be controlled to give a wide
range of glass transition temperatures in the cured adhesive to
withstand subsequent processing and operation temperatures.
[0013] In the inventive adhesive compositions, the maleimide
compounds and the vinyl compounds may be used independently, or in
combination. The maleimide or vinyl compounds, or both, will be
present in the curable package adhesive compositions in an amount
from 2 to 98 weight percent based on the organic components present
(excluding any fillers).
[0014] The adhesive compositions will further comprise at least one
free-radical initiator, which is defined to be a chemical species
that decomposes to a molecular fragment having one or more unpaired
electrons, highly reactive and usually short-lived, which is
capable of initiating a chemical reaction by means of a chain
mechanism. The free-radical initiator will be present in an amount
of 0.1 to 10 percent, preferably 0.1 to 3.0 percent, by weight of
the organic compounds (excluding any filler). The free radical
curing mechanism gives a fast cure and provides the composition
with a long shelf life before cure. Preferred free-radical
initiators include peroxides, such as butyl peroctoates and dicumyl
peroxide, and azo compounds, such as 2,2'-azobis(2-methyl-propane-
nitrile) and 2,2'-azobis(2-methyl-butanenitrile).
[0015] Alternatively, the adhesive compositions may contain a
photoinitiator in lieu of the free-radical initiator, and the
curing process may then be initiated by UV radiation. The
photoinitiator will be present in an amount of 0.1 to 10 percent,
preferably 1 to 5.0 percent, by weight of the organic compounds
(excluding any filler). In some cases, both photoinitiation and
thermal initiation may be desirable. For example, the curing
process can be started by UV irradiation, and in a later processing
step, curing can be completed by the application of heat to
accomplish a free-radical cure.
[0016] In general, these compositions will cure within a
temperature range of 80-200.degree. C., and curing will be effected
within a length of time of less than 1 minute to 60 minutes. As
will be understood, the time and temperature curing profile for
each adhesive composition will vary, and different compositions can
be designed to provide the curing profile that will be suited to
the particular industrial manufacturing process.
[0017] Suitable conductive fillers for the adhesives are silver,
copper, gold, palladium, platinum. In some circumstances,
nonconductive fillers may be needed, for example to adjust
rheology, such as, alumina, silica, and teflon.
[0018] As used throughout this specification, the notation C(O)
refers to a carbonyl group.
Maleimide Compounds
[0019] The maleimide compounds suitable for use in the adhesive
compositions of this invention have a structure represented by the
formula: [M-X.sub.m].sub.n-Q, or by the formula:
[M-Z.sub.m].sub.n--K. For these specific formulae, when lower case
"n" is the integer 1, the compound will be a mono-functional
compound; and when lower case "n" is an integer 2 to 6, the
compound will be a poly-functional compound.
[0020] [M-X.sub.m]n.sub.-Q, or by the formula:
[M-Z.sub.m].sub.n-K.
[0021] Formula [M-X.sub.m].sub.n-Q represents those compounds in
which:
[0022] M is a maleimide moiety having the structure 1
[0023] in which R.sup.1 is H or C.sub.1 to C.sub.5 alkyl;
[0024] each X independently is an aromatic group selected from the
aromatic groups having the structures (I) through (IV): 2
[0025] Q is a linear or branched chain alkyl, alkyloxy, alkylene,
alkyleneoxy, aryl, or aryloxy alkyl amine, alkyl sulfide, alkylene
amine, alkylene sulfide, aryl sulfide species, which may contain
saturated or unsaturated cyclic or heterocyclic substituents
pendant from the chain or as part of the backbone in the chain, and
in which any heteroatom present may or may not be directly attached
to X;
[0026] or Q is a urethane having the structure: 3
[0027] in which each R.sup.2 independently is an alkyl, aryl, or
arylalkyl group having 1 to 18 carbon atoms; R.sup.3 is an alkyl or
alkyloxy chain having up to 100 atoms in the chain, which chain may
contain aryl substituents; X is O, S, N, or P; and v is 0 to
50;
[0028] or Q is an ester having the structure: 4
[0029] in which R.sup.3 is an alkyl or alkyloxy chain having up to
100 atoms in the chain, which chain may contain aryl
substituents;
[0030] or Q is a siloxane having the structure:
--(CR.sup.1.sub.2).sub.e---
[SiR.sup.4--O].sub.f--SiR.sup.4.sub.2--(CR.sup.1.sub.2).sub.0-- in
which the R.sup.1 substituent independently for each position is H
or an alkyl group having 1 to 5 carbon atoms and the R.sup.4
substituent independently for each position is H, an alkyl group
having 1 to 5 carbon atoms or an aryl group, and e and g are
independently 1 to 10 and f is 1 to 50; and
[0031] m is 0 or 1, and n is 1 to 6.
[0032] Preferred compositions are aliphatic bismaleimides in which
the maleimide functionality is linked to the backbone through
urethane or urea linkages, such as in the following preferred
compounds: 5
[0033] Formula [M-Z.sub.m].sub.n"K represents those compounds in
which
[0034] M is a maleimide moiety having the structure 6
[0035] in which R.sup.1 is H or C.sub.1 to C.sub.5 alkyl;
[0036] Z is a linear or branched chain alkyl, alkyloxy, alkyl
amine, alkyl sulfide, alkylene, alkyleneoxy, alkylene amine,
alkylene sulfide, aryl, aryloxy, or aryl sulfide species, which may
contain saturated or unsaturated cyclic or heterocyclic
substituents pendant from the chain or as part of the backbone in
the chain, and in which any heteroatom present may or may not be
directly attached to K;
[0037] or Z is a urethane having the structure: 7
[0038] in which each R.sup.2 independently is an alkyl, aryl, or
arylalkyl group having 1 to 18 carbon atoms, and R.sup.3 is an
alkyl or alkyloxy chain having up to 100 atoms in the chain, which
chain may contain aryl substituents, and v is 0 to 50;
[0039] or Z is a siloxane having the structure:
--(CR.sup.1.sub.2).sub.e---
[SiR.sup.4.sub.2--O].sub.f--SiR.sup.4.sub.2--(CR.sup.1.sub.2).sub.g--
in which the R.sup.1 substituent independently for each position is
H or an alkyl group having 1 to 5 carbon atoms and the R.sup.4
substituent independently for each position is H, an alkyl group
having 1 to 5 carbon atoms or an aryl group, and e and g are
independently 1 to 10 and f is 1 to 50;
[0040] K is an aromatic group selected from the aromatic groups
having the structures (VI) through (XIII) (although only one bond
may be shown to represent connection to the aromatic group K, this
will be deemed to represent any number of additional bonds as
described and defined by n): 8 9
[0041] in which R.sup.5, R.sup.6, and R.sup.7 are a linear or
branched chain alkyl, alkyloxy, alkyl amine, alkyl sulfide,
alkylene, alkyleneoxy, alkylene amine, alkylene sulfide, aryl,
aryloxy, or aryl sulfide species, which may contain saturated or
unsaturated cyclic or heterocyclic substituents pendant from the
chain or as part of the backbone in the chain, and in which any
heteroatom present may or may not be directly attached to the
aromatic ring; or R.sup.5, R.sup.6, and R.sup.7 are a siloxane
having the structure --(CR.sup.1.sub.2).sub.e--[SiR.sup.4.sub.2--
-O].sub.f--SiR.sup.4 .sub.2--(CH.sub.3).sub.g-- in which the
R.sup.1substituent is H or an alkyl group having 1 to 5 carbon
atoms and the R.sup.4 substituent independently for each position
is an alkyl group having 1 to 5 carbon atoms or an aryl group, and
e is 1 to 10 and f is 1 to 50; 10
[0042] and m is 0 or 1, and n is 1 to 6.
[0043] Preferred maleimide compounds, particularly for reworkable
compositions, are N-butyphenyl malemide and N-ethylpenyl
maleimide.
Vinyl Compounds
[0044] The vinyl compounds (other than the maleimdes herein)
suitable for use in the adhesive compositions of this invention
will have the structure: 11
[0045] For these specific structures, when lower case "n" is the
integer 1, the compound will be a mono-functional compound; and
when lower case "n" is an integer 2 to 6, the compound will be a
poly-functional compound.
[0046] In these structures, R.sup.1 and R.sup.2 are H or an alkyl
having 1 to 5 carbon atoms, or together form a 5 to 9 membered ring
with the carbons forming the vinyl group; B is C, S, N, O, C(O),
O--C(O), C(O)--O, C(O)NH or C(O)N(R.sup.8), in which R.sup.8 is
C.sub.1 to C.sub.5 alkyl; m is 0 or 1; n is 1-6; and X, Q, Z, and K
are as described above.
[0047] Preferably, B is O, C(O), C(O)--O, C(O)NH or C(O)N(R.sup.8);
more preferably B is O, C(O), O--C(O), C(O)--O, or
C(O)N(R.sup.8).
[0048] Preferred vinyl compounds for use as adhesives are vinyl
ethers or alkenyl sufides. Examples of suitable vinyl compounds are
the following: 12
Other Composition Components
[0049] Depending on the nature of the substrate to which the
adhesive is to be bonded, the adhesive may also contain a coupling
agent. A coupling agent as used herein is a chemical species
containing a polymerizable functional group for reaction with the
maleimide and other vinyl compound, and a functional group capable
of condensing with metal hydroxides present on the surface of the
substrate. Such coupling agents and the preferred amounts for use
in compositions for particular substrates are known in the art.
Suitable coupling agents are silanes, silicate esters, metal
acrylates or methacrylates, titanates, and compounds containing a
chelating ligand, such as phosphine, mercaptan, and acetoacetate.
When present, coupling agents typically will be in amounts up to 10
percent by weight, and preferably in amounts of 0.1-3.0 percent by
weight, of the maleimide and other monofunctional vinyl
compound.
[0050] In addition, the adhesive compositions may contain compounds
that lend additional flexibility and toughness to the resultant
cured adhesive. Such compounds may be any thermoset or
thermoplastic material having a Tg of 50.degree. C. or less, and
typically will be a polymeric material characterized by free
rotation about the chemical bonds, the presence of ether groups,
and the absence of ring structures. Suitable such modifiers include
polyacrylates, poly(butadiene), polyTHF ( polymerized
tetrahydrofuran), CTBN (carboxy-terminated butadiene-acrylonitrile)
rubber, and polypropylene glycol. When present, toughening
compounds may be in an amount up to about 15 percent by weight of
the maleimide and other monofunctional vinyl compound.
[0051] If siloxane moieties are not part of the maleimide or vinyl
compound structure, siloxanes can be added to the package
formulations to impart elastomeric properties. Suitable siloxanes
are the methacryloxypropyl-terminated polydimethyl siloxanes, and
the aminopropyl-terminated polydimethylsiloxanes, available from
United Chemical Technologies and others.
[0052] Other additives, such as adhesion promoters, in types and
amounts known in the art, may also be added.
Performance Properties
[0053] These compositions will perform within the commercially
acceptable range for die attach adhesives. Commercially acceptable
values for die shear for the adhesives on a 80.times.80 mil.sup.2
silicon die are in the range of greater than or equal to 1 kg at
room temperature, and greater than or equal to 0.5 kg at
240.degree. C., and for warpage for a 500.times.500 mil.sup.2 die
are in the range of less than or equal to 70 .mu.m at room
temperature.
[0054] The coefficient of thermal expansion (CTE) is the change in
dimension per unit change in temperature for a given material.
Different materials will have different rates of expansion. If the
CTE is very different for elements attached together, thermal
cycling can cause the attached elements to bend, crack, or
delaminate. In a typical semiconductor assembly, the CTE of the
chip is in the range of 2 or 3 ppm/.degree. C.; for organic circuit
board substrate, the CTE is greater than 30 ppm/.degree. C.;
therefore, the CTE of the adhesive is best between that of the
substrate and die.
[0055] When a polymer is subjected to the application of heat, it
will move through a transition region between a hard, glassy state
to a soft, rubbery state. This region is known as the glass
transition region or Tg. If a graph of expansion of the polymer
versus temperature is plotted, the glass transition region is the
intersection between the lower temperature/glassy region
coefficient of thermal expansion and the higher temperature/rubbery
region coefficient of thermal expansion. Above this region, the
rate of expansion increases significantly. Consequently, it is
preferred that the glass transition of the polymer be higher than
normal operating temperatures experienced during the application,
and if reworkability is needed, that the glass transition be lower
than any rework temperature.
[0056] Another embodiment of this invention includes the maleimides
having the formulae [M-X.sub.m].sub.n-Q and [M-Z.sub.m].sub.n-K as
described herein in which Q and Z can be an ester having the
structure 13
[0057] in which p is 1 to 100,
[0058] each R.sup.3 can independently be an alkyl or alkyloxy chain
having up to 100 atoms in the chain, which chain may contain aryl
substituents, or
[0059] a siloxane having the structure
--(CR.sup.1.sub.2).sub.e--[SiR.sup.-
4.sub.2--O].sub.f--SiR.sup.4.sub.2--(CR.sup.1.sub.2--).sub.g in
which the R.sup.1 substituent independently for each position is H
or an alkyl group having 1 to 5 carbon atoms, the R.sup.4
substituent independently for each position is an alkyl group
having 1 to 5 carbon atoms or an aryl group, e and g are
independently 1 to 10 and f is 1 to 50.
[0060] Another embodiment of this invention includes the vinyl
compounds having the structures 14
[0061] as described herein in which B is C, S, N, O, C(O), C(O)NH
or C(O)N(R.sup.8), in which R.sup.8 is C.sub.1 to C.sub.5
alkyl.
[0062] Another embodiment of this invention includes the vinyl
compounds having the structures 15
[0063] as described herein in which Q and Z can be an ester having
the structure 16
[0064] in which p is 1 to 100,
[0065] each R.sup.3 can independently be an alkyl or alkyloxy chain
having up to 100 atoms in the chain, which chain may contain aryl
substituents,
[0066] or a siloxane having the structure
[0067]
--(CR.sup.1.sub.2).sub.e--[SiR.sup.4.sub.2--O].sub.f--SiR.sup.4.sub-
.2--(CR.sup.1.sub.2).sub.g-- in which the R.sup.1 substituent
independently for each position is H or an alkyl group having 1 to
5 carbon atoms, the R.sup.4 substituent independently for each
position is an alkyl group having 1 to 5 carbon atoms or an aryl
group, e and g are independently 1 to 10, and f is 1 to 50.
[0068] Another embodiment of this invention includes the curable
adhesive composition as described herein containing an anionic or
cationic curing initiator. The types and useful amounts of such
initiators are well known in the art.
EXAMPLES
[0069] Various maleimide and vinyl compounds were prepared and
formulated into adhesive compositions. The compositions were
investigated for viscosity and thixotropic index for the uncured
composition, and for curing profile, glass transition temperature,
coefficient of thermal expansion, thermal mechanical analysis, and
in some cases reworkability for the cured composition.
Example 1
Preparation of Butadiene-Acrylonitrile Bismaleimide
[0070] 17
[0071] Amino-terminated butadiene-acrylonitrile (sold as Hycar
resin 1300 X42 ATBN by BF Goodrich, in which the m and n depicted
in the structure are integers to provide a number average molecular
weight of 3600) (450 g, 500 mmol based on amine equivalent weight
AEW=450 g) was dissolved in CHCl.sub.3 (1000 mL) in a 3 L
four-necked flask equipped with addition funnel, mechanical
stirrer, internal temperature probe and nitrogen inlet/outlet. The
stirred solution was placed under nitrogen and cooled on an ice
bath. The addition funnel was charged with maleic anhydride (98.1
g, 1 mol) in CHCl.sub.3 (50 mL) and this solution was added to the
reaction over 30 minutes, maintaining the internal reaction
temperature below 10.degree. C. This mixture was stirred for 30
minutes on ice, then allowed to warm to room temperature and
stirred for an additional 4 hours. To the resulting slurry was
added acetic anhydride (Ac.sub.2O) (653.4 g, 6 mol), triethylamine
(Et.sub.3N) (64.8 g, 0.64 mol) and sodium acetate (NaOAc) (62.3 g,
0.76 mol). The reaction was heated to mild reflux for 5 hours,
allowed to cool to room temperature, and subsequently extracted
with H.sub.2O (1 L), satd. NaHCO.sub.3 (1 L) and H.sub.2O
(2.times.1 L). Solvent was removed in vacuo to yield the maleimide
terminated butadiene acrylonitrile.
Example 2
Preparation of Tris(maleimide) Derived From
Tris(epoxypropyl)isocyanurate
[0072] 18
[0073] Tris(epoxypropyl)isocyanurate (99.0 g, 0.33 mol) is
dissolved in THF (500 mL) in a 2 L three-necked flask equipped with
mechanical stirrer, internal temperature probe and nitrogen
inlet/outlet. To this solution is added hyroxyphenylmaleimide
(189.2 g, 1 mol) and benzyldimethylamine (1.4 g, 0.05 wt. %). The
solution is heated to 80.degree. C. for 7 hours. The reaction then
is allowed to cool to room temperature, is filtered, and the
filtrant washed with 5% HCl.sub.aq (500 mL) and distilled H.sub.2O
(1 L). The resulting solid, triazinetris(maleimide), is vacuum
dried at room temperature.
Example 3
Preparation of Maleimidoethylpalmitate
[0074] 19
[0075] Palmitoyl chloride (274.9 g, 1 mol) is dissolved in
Et.sub.2O (500 mL) in a 2 L three-necked flask equipped with
mechanical stirrer, internal temperature probe, addition funnel and
nitrogen inlet/outlet. NaHCO.sub.3 (84.0 g, 1 mol) in distilled
H.sub.2O (500 mL) is added with vigorous stirring and the solution
cooled on an ice bath under nitrogen. The addition funnel is
charged with hydroxyethylmaleimide (141 g, 1 mol) in Et.sub.2O (100
mL) and this solution added to the reaction over a period of 30
minutes, maintaining an internal T<10.degree. C. during the
addition. The reaction is stirred for another 30 minutes on ice,
then allowed to warm to room temperature and stirred for 4 hours.
The reaction is transferred to a separatory funnel and the isolated
organic layer washed with distilled H.sub.2O (500 mL), 5%
HCl.sub.aq (500 mL) and distilled H.sub.2O (2.times.500 mL). The
organics are isolated, dried over MgSO.sub.4 anhyd., filtered and
solvent removed in vacuo to yield the aliphatic maleimide.
Example 4
Preparation of Bismaleimide Derived from
5-Isocyanato-1-(isocyanatomethyl)- -1, 3,
3-trimethylcyclohexane
[0076] 20
[0077] 5-Isocyanato-1-(isocyanatomethyl )-1, 3,
3-trimethylcyclohexane 111.15 g, 0.5 mol) is solvated in THF (500
mL) in a 1 L three-necked flask equipped with mechanical stirrer,
addition funnel and nitrogen inlet/outlet. The reaction is placed
under nitrogen, and dibutyltin dilaurate (cat. Sn.sup.II) (6.31 g,
10 mmol) and hydroxyethylmaleimide (141 g, 1 mol) are added with
stirring, and the resulting mixture heated for four hours at
70.degree. C. The addition funnel is charged with
hydroxyethylmaleimide (141 g, 1 mol) dissolved in THF (100 mL).
This solution is added to the isocyanate solution over 30 minutes,
and the resulting mixture heated for an additional 4 hours at
70.degree. C. The reaction is allowed to cool to room temperature
and solvent removed in vacuo. The remaining oil is dissolved in
CH.sub.2Cl.sub.2 (1 L) and washed with 10% HCl.sub.aq (1 L) and
distilled H.sub.2O (2.times.1 L). The isolated organics are dried
over MgSO.sub.4, filtered and the solvent removed in vacuo to yield
the maleimide.
Example 5
Preparation of Dimer Divinyl Ether Derived From Pripol 2033
[0078] 21
[0079] Bis(1, 10-phenanthroline)Pd(OAc).sub.2 (0.21 g, 0.54 mmol)
was dissolved in a mixture of butyl vinyl ether (8.18 g, 81.7
mmols), heptane (100 mL) and "dimer diol" (sold as Pripol 2033 by
Unichema, 15.4 g, 27.2 mmol) in 2 L three-necked flask equipped
with a mechanical stirrer under nitrogen. This solution was heated
to light reflux for 6 h. The solution was allowed to cool to room
temperature and subsequently poured onto activated carbon (20 g)
and stirred for 1 hour. The resulting slurry was filtered, and
excess butyl vinyl ether and heptane were removed in vacuo to yield
the divinyl ether as a yellow oil. The product exhibited acceptable
.sup.1H NMR, FT-IR and .sup.13C NMR spectral characteristics.
Typical viscosity .about.100 cPs.
Example 6
Preparation of Dimer Diacrylate Derived From Dimer Diol (Pripol
2033)
[0080] 22
[0081] A dimer diol (sold as Pripol 2033 by Unichema, 284.4 g, 500
mmol) is dissolved in dry acetone (500 mL) in a 1 L three-necked
flask equipped with mechanical stirrer, addition funnel and
internal temperature probe under nitrogen. Triethylamine (101.2 g,
1 mol) is added to this solution and the solution cooled to
4.degree. C. on an ice bath. Acryloyl chloride (90.5 g, 1 mol)
solvated in dry acetone (100 mL) is charged into the addition
funnel and added to the stirred reaction solution over the course
of 60 minutes, maintaining an internal temperature <10.degree.
C. This solution is stirred on ice for an additional 2 hours, then
allowed to warm to room temperature and stirred for 4 hours. Bulk
solvent is removed via a rotary evaporator, and the remaining
residue solvated in CH.sub.2Cl.sub.2 (1 L). This solution is washed
with 5% HCl.sub.aq (800 mL), and H.sub.2O (2.times.800mL). The
isolated organics are dried over MgSO.sub.4 anhyd. and filtered,
and the solvent removed in vacuo to yield the diacrylate as an
oil.
Example 7
Preparation of N-ethylphenyl Maleimide
[0082] 4-Ethyl aniline (12.12 g) was dissolved in 50 ml of
anhydrous ethyl ether and slowly added to a stirred solution of
9.81 g of maleic anhydride in 100 ml of anhydrous ethyl ether
chilled in an ice bath. After completion of the addition, the
reaction mixture was stirred for 30 minutes. The light yellow
crystals were filtered and dried. Acetic anhydride (200 ml) was
used to dissolve the maleamic acid and 20 g of sodium acetate. The
reaction mixture was heated in an oil bath at 1 60.degree. C. After
3 hours of reflux, the solution was cooled to room temperature,
placed in a 1 L beaker in ice water and stirred vigorously for 1
hour. The product was suction-filtered and recrystallized in
hexane. The collected crystalline material was dried at 50.degree.
C. in a vacuum oven overnight. FTIR and NMR analysis showed the
characteristics of ethyl maleimide.
Example 8
Preparation of Bis(alkenylsulfide)
[0083] 23
[0084] Dimer acid (sold under the trademark Empol 1024 by Unichema)
(574.6 g, 1 mol) and propargyl alcohol (112.1 g, 2 mol) are
solvated in toluene (1 L) in a 3 L three-necked flask equipped with
mechanical stirring and a Dean-Stark distillation apparatus.
Concentrated H.sub.2SO.sub.4 (6 mL) is added and the solution
refluxed for 6 hours until 36 mL of H.sub.2O is azeotropically
distilled. The solution is allowed to cool to room temperature, is
washed with H.sub.2O (2.times.1L), dried over MgSO.sub.4 anhyd, and
the solvent removed in vacuo to yield the propargyl ester
intermediate as an oil.
[0085] This ester intermediate (650.7 g, 1 mol) is solvated in THF
(200 mL) in a 1 L three-necked flask equipped with reflux
condensor, mechanical stirrer and internal temperature probe under
nitrogen. Lauryl mercaptan (404.8 g, 2 mol) and
2,2'-azobis(2,4-dimethylpentanenitrile) (sold under the trademark
Vazo 52 by DuPont) (11 g) are added and the resulting mixture
heated to 70.degree. C. on an oil bath with stirring for 7 hours.
The reaction is allowed to cool to room temperature and solvent
removed in vacuo to yield the alkenyl sulfide as an oil.
Example A
Preparation of 6-maleimidocaproic Acid
[0086] 24
[0087] The acid functional maleimide, 6-maleimidocaproic acid, was
synthesized using known methodology..sup.1 Aminocaproic acid (100
g, 7.6.times.10.sup.-1 mols) was dissolved in glacial acetic acid
(50 mL) in a 500 mL four-necked flask equipped with mechanical
stirring, an internal temperature probe and an addition funnel. The
addition funnel was charged with a solution of maleic anhydride
(74.8 g, 7.6.times.10.sup.-1 mols) dissolved in acetonitrile (75
mL). This solution was added to the aminocaproic acid at room
temperature dropwise over 1 hour, maintaining an internal reaction
temperature less than 35.degree. C. The reaction was stirred for
three hours after the addition was complete. The reaction slurry
was filtered, and the isolated filtrate was dried in a vacuum oven
(P.about.25 T) overnight at 70.degree. C. to yield 166 g of off
white solid (95%). The product amic acid exhibited FT-IR and
.sup.1H NMR spectral characteristics consistent with literature
data.
[0088] The amic acid described above (166 g, 7.2.times.10.sup.-1
mols) was solvated in a solution of toluene (200 mL), benzene (200
mL) and triethylamine (211 mL, 1.51 mol) in a 1 L three-necked
flask equipped with mechanical stirring and a Dean-Stark trap under
nitrogen. This solution was heated to reflux for 4 h and the water
produced collected in the Dean-Stark trap. Distilled water (400 mL)
was added to the reaction flask to dissolve the triethylammonium
salt of the product which largely separated from the bulk solution
during the reaction. This aqueous layer was isolated, acidified to
pH.about.1 with 50% HCl, and extracted with ethyl acetate (600 mL).
This organic layer was washed with distilled water (400 mL). The
isolated organic layer was dried over MgSO.sub.4, followed by
solvent removal in vacuo to yield an off white solid (76.2 g, 50%).
The product 6-maleimidocaproic acid was spectrographically
identical to literature material by FT-IR and .sup.1H NMR.
Example B
Preparation of "Dimer Diester Bismaleimide"
[0089] 25
[0090] Pripol 2033 ("dimer diol", Uniqema, 92.4 g,
1.69.times.10.sup.-1 mols), 6-maleimidocaproic acid (75.0 g,
3.55.times.10.sup.-1 mols) and H.sub.2SO.sub.4 (0.50 mL,
.about.8.5.times.10.sup.-3 mols) were slurried in toluene (300 mL)
in a 1 L four-necked flask equipped with mechanical stirrer, a
Dean-Stark trap and an internal temperature probe under nitrogen.
The reaction was heated to light reflux for two hours and the water
evolved collected in the Dean-Stark trap. The trap was drained and
.about.50 mL of toluene solvent was distilled off of the reaction
to remove trace moisture and drive the esterification equilibrium
to completion. The reaction was allowed to cool to room
temperature, additional toluene (100 mL) was added (on the
laboratory scale it is preferable to add diethyl ether in place of
toluene at this point), and the solution was washed with saturated
NaHCO.sub.3 aq. (300 mL) and distilled water (300 mL). The organic
layer was isolated and dried over anhydrous MgSO.sub.4, and the
solvent removed in vacuo to yield an orange oil (107.2 g, 68%). The
material can be further purified by eluting a toluene solution of
the resin through a short plug of silica or alumina. This liquid
bismaleimide resin exhibited acceptable FT-IR, .sup.1H NMR, and
.sup.13C NMR data. Typical .eta..about.2500 cPs.
Example C
Preparation of "Decane Diol Diester Bismaleimde"
[0091] 26
[0092] The general procedure described in Example B. was applied
substituting decane diol (29.5 g, 1.69.times.10.sup.-1 mols) for
Pripol 2033. This process yielded a solid, moderately soluble
bismaleimide (54.9 g, 58%). The product exhibited satisfactory
FT-IR and .sup.1H NMR data.
Example D
Preparation of "Glycerol Triester Tris(maleimide)"
[0093] 27
[0094] The protocol outlined in example B. was utilized
substituting glycerol (10.4 g, 1.13.times.10.sup.-1 mol) for Pripol
2033. The product was a viscous liquid which exhibited acceptable
FT-IR and .sup.1H NMR data.
Example E
Preparation of "Bis(m-nitrobenzyl carbamate) of IPDI"
[0095] 28
[0096] Isophorone diisocyanate ("IPDI", 100.0 g,
4.5.times.10.sup.-1 mols), m-nitrobenzyl alcohol (137.8 g,
9.0.times.10.sup.-1 mols) and dibutyl tin dilaurate (2.8 g,
4.5.times.10.sup.-3 mols) were solvated in dry toluene (1500 mL) in
a 2 L three-necked flask equipped with mechanical stirrer, reflux
condensor and internal temperature probe under nitrogen. The
resulting solution was heated to 90.degree. C. for 4 h. No
isocyanate band was observed in the IR of the solids portion of the
sample. The solution was allowed to cool to room temperature and
washed with distilled H.sub.2O (100 mL). The organic layer was
isolated and solvent removed in vacuo to yield a yellow liquid
which exhibited acceptable FT-IR and .sup.1H NMR
characteristics.
Example F
Preparation of "Bis(m-aminobenzyl carbamate) of IPDI"
[0097] 29
[0098] The dinitro compound from Example E. (8.28 g,
1.57.times.10.sup.-2 mols) was dissolved in ethanol (100 mL) in a
500 mL three-necked round bottom flask equipped with magnetic
stirring under nitrogen. Cyclohexene (28.6 mL, 2.82.times.10.sup.-1
mols) was added, followed by 5% Pd/C (4.14 g). The resulting slurry
was refluxed lightly for 6.5 h. The FT-IR of a filtered aliquot of
this solution exhibited no nitro stretching bands at 1529 cm.sup.-1
and 1352 cm.sup.-1. The bulk solution was allowed to cool to room
temperature and filtered. Solvent was removed in vacuo to yield a
yellow semisolid (6.6 g, 90%) which exhibited acceptable FT-IR and
.sup.1H NMR spectral characteristics.
Example G
Preparation of "Bis(m-maleimidobenzyl carbamate) of IPDI"
[0099] 30
[0100] The diamine from Example F (6.6 g, 1.41.times.1.sup.-2 mols)
was solvated in acetone (60 mL) in a 250 mL four-necked flask
equipped with magnetic stirrer and addition funnel under nitrogen
and cooled to 4.degree. C. Maleic anhydride (2.76 g,
2.82.times.10.sup.-2 mols) dissloved in acetone (20 mL) was added
over the course of 30 minutes. The resulting solution was stirred
at 4.degree. C. for for 1 h, and subsequently was allowed to warm
to room temperature and stirred overnight. FT-IR analysis indicated
no maleic anhydride remained as judged by the absence of the
anhydride stretching band at .about.1810 cm.sup.-1.
[0101] To the above amic acid solution was added acetic anhydride
(8.5 mL, 9.0.times.10.sup.-2 mols), triethylamine (1.26 mL,
9.0.times.10.sup.-3 mols) and sodium acetate (0.88 g,
1.1.times.10.sup.-2 mols). The resulting solution was refluxed
lightly for 4 h under nitrogen. The reaction was allowed to cool to
room temperature and bulk solvent was removed in vacuo. The
resulting viscous liquid was resolvated in methylene chloride (200
mL) and extracted with distilled water (3.times.200 mL). The
organics were then dried over MgSO.sub.4 anhyd., filtered and
solvent removed in vacuo to yield a light brown solid (6.75 g,
76%). This material exhibited acceptable FT-IR and .sup.1H NMR
spectral features.
Example H
Preparation of "Bis(m-nitrobenzyl carbamate) of DDI 1410"
[0102] 31
[0103] DDI 1410 (Henkel, "Dimer Diisocyanate", 99.77 g,
1.65.times.10.sup.-1 mols based on 13.96% NCO), m-nitrobenzyl
alcohol (50.8 g, 3.32.times.10.sup.-1 mols) and dibutyltin
dilaurate (0.5 mL, 8.3.times.10.sup.-4 mols) were solvated in
toluene (150 mL) in a 1 L four-necked flask equipped with
mechanical stirrer, reflux condenser and internal temperature probe
under nitrogen. The reaction was heated to 85.degree. C. for 2.5 h.
FT-IR analysis of an aliquot of the reaction indicated complete
comsumption of isocyanate functionality as judged by the lack of a
band at 2272 cm.sup.-1. Solvent was removed from the reaction in
vacuo to yield a yellow oil which solidified upon standing at room
temperature (152.4 g, 102% (trace toluene)). This solid exhibited
satisfactory FT-IR and .sup.1H NMR spectral features.
Example I
Preparation of "Bis(m-aminobenzyl carbamate) of DDI 1410"
[0104] 32
[0105] The diamine product of Example H (39.6 g,
4.32.times.10.sup.-2 mols) and stannous chloride dihydrate (97.55
g, 4.32.times.10.sup.-1 mols) were slurried in ethyl acetate (300
mL) in a 1 L three-necked flask equipped with mechanical stirrer
and a reflux condensor under nitrogen. The reaction was heated to
light reflux and stirred vigorously for 3 h. The solution was
allowed to cool to room temperature and brought to pH 7-8 with a
solution of saturated sodium bicarbonate. The mixture was pushed
through a 25 micron filter to yield a mixture which separated into
a cloudy aqueous layer and a moderately clear organic layer. The
aqueous layer was isolated and washed with ethyl acetate (100 mL).
The organic layers were combined, washed with distilled water (300
mL) and dried over anhydrous MgSO.sub.4. The slurry was filtered
and solvent removed from the filtrate in vacuo to yield yellow,
sticky solid (33.8 g, 92%).
Example J
Preparation of "Bis(m-maleimidobenzyl carbamate) of DDI 1410"
[0106] 33
[0107] Maleic anhydride (15.4 g, 1.57.times.10.sup.-2 mols) was
dissolved in acetone (300 mL) in a 2 L four-necked flask equipped
with mechanical stirrer, internal temperature probe and addition
funnel under nitrogen. This solution was cooled to .about.4.degree.
C. on an ice bath. A solution of the diamine prepared in Example I
(63.4 g, 7.48.times.10.sup.-2 mols) in acetone (70 mL) was charged
to the addition funnel and added to the maleic anhydride solution
over a period of 30 minutes maintaining an internal temperature of
<10.degree. C. The resulting solution was stirred for 1 h and
subsequently allowed to warm to room temperature and stir for 2
h.
[0108] To this solution of amic acid was added acetic anhydride
(24.7 mL, 2.62.times.10.sup.-1 mols), triethylamine (6.25 mL,
4.48.times.10.sup.-2 mols) and manganese acetate tetrahydrate (0.37
g, 1.50.times.10.sup.-3 mols). This solution was heated to light
reflux for 6.5 h, then allowed to cool to room temperature. Bulk
solvent was removed in vacuo, and the resulting dark liquid was
dissolved in diethyl ether (500 mL). This solution was washed with
dist. H.sub.2O (500 mL). The isolated organic layer was then washed
with saturated NaHCO.sub.3 aq. (500 mL) and again with dist.
H.sub.2O (500 mL). The organics were isolated, dried over anhyd.
MgSO.sub.4, and solvent removed in vacuo to yield a viscous orange
oil. This material exhibited FT-IR, .sup.1H NMR and .sup.13C NMR
spectral features consistent with the expected bismaleimide
product.
Example AA
Low Stress Die Attach Adhesive Formulation and Die Shear Strengths
on Various Leadframes
[0109] A silver filled die attach adhesive formulation having a
viscosity of 9011 cPs (5 rpm, cone and plate) and thixotropic index
of 5.36 was produced by combining the following at room temperature
using a mechanical mixer:
1 Liquid bismaleimide of Example B: 2.644 g Dimer divinyl ether of
Example 5: 2.644 g Ricon 131MA20 (Ricon Resins, Inc.): 0.661 g
Silquest A-174 (Witco Corp.): 0.040 g USP-90MD (Witco Corp.): 0.099
XD0026 (NSCC trade secret): 0.119 SF-96 silver flake 23.794
[0110] The resulting paste was dispensed onto various metal
leadframes as detailed below, and 120.times.120 mil silicon die
were placed onto the adhesive bead to produce an approximately 1
mil bondline. Samples were "snap cured" at 200.degree. C. for 60
seconds, and die shear strengths at room temperature and
240.degree. C. were measured. These samples were then subjected to
elevated temperature and humidity (85.degree. C./85% RH) for 48
hours. Die shear strengths were then again measured at room
temperature and 240.degree. C. Results are tabulated in Table
1.
2TABLE 1 Die Shear Strengths (DSS) of Maleimide/Vinyl Ether Die
Attach Adhesive After Moisture Exposure No Moisture Exposure (48
h/85.degree. C./85 RH) Cure Profile 60 s/200.degree. C. 60
s/200.degree. C. Test 25.degree. C. 240.degree. C. 25.degree. C.
240.degree. C. Temperature Cu leadframe 4.88+/- 1.46+/- 6.54+/-0.82
1.84+/-0.76 DSS (kg) 0.25 0.35 Ag-Cu 5.29+/- 2.17+/- 9.50+/-1.88
1.56+/-0.72 leadframe 0.34 0.43 DSS (kg) Pd-Cu 5.52+/- 1.99+/-
11.9+/-1.3 3.53+/-0.66 DSS (kg) 0.39 0.44 Typical moisture uptake
for these devices after saturation at 85.degree. C./85% RH was 0.18
weight percent. Weight loss during cure was 0.16 +/- 0.05 weight
percent.
Example BB
HAST Testing of Maleimide/Vinyl Ether Die Attach Adhesive
[0111] Similarly to Example AA, 120.times.120 mil die were attached
to leadframes of various compositions utilizing the adhesive
composition given in Example AA. The bonded die were then cured
using "snap cure" (60 s/200.degree. C.) and "fast oven cure"
conditions (15 min./175.degree. C.). The resulting cured devices
were subjected to simulated HAST testing conditions (130.degree.
C., 85% RH) for 130 hours. The devices exhibited good adhesion as
measured by die shear strength (DSS) at both room temperature and
elevated temperature as shown in Table 2.
3TABLE 2 Die Shear Strengths after simulated HAST Testing Cure
Profile 60 s/200.degree. C. 15 minutes/175.degree. C. Test
25.degree. C. 240.degree. C. 25.degree. C. 240.degree. C.
Temperature Cu leadframe 15.3+/- 1.12+/-0.35 17.2+/- 1.25+/-0.39
DSS (kg) 1.8 Ag--Cu 16.3+/- 2.81+/-0.55 14.8+/- 2.6+/-1.6 leadframe
1.9 1.8 DSS (kg) Pd--Cu 15.7+/ 3.04+/-0.46 14.4+/- 2.96+/-0.90 DSS
(kg) 1.7 0.7
Example CC
Warpage of Large Die Bonded with Maleimide/Vinyl Ether Die Attach
Adhesive
[0112] The die attach composition described in Example AA. was used
to bond 500.times.500 mil die to Pd-Cu leadframes. The assembled
pieces were "snap cured" and measured for die warpage at several
temperatures and times. Typical results are given in Table 3. The
performance exhibited by this adhesive qualifies it as a "low
stress" material.
4TABLE 3 Warpage of Maleimide/Vinyl Ether Die Attach Adhesive on
500 .times. 500 mil Die Thermal History 1 min/200.degree. C. +1
min/240.degree. C. +4 h/175.degree. C. Warpage (.mu.m) 10.4+/-1.3
11.9+/-1.4 14.1+/-1.6
Example DD
Thermal Analysis of Maleimide/Vinyl Ether Die Attach Adhesive
[0113] The composition of Example AA. was used to produce .about.1
mil films using a drawdown bar. The films were "snap cured" (60 s,
200.degree. C.) on a hot plate or oven cured (4 h/75.degree. C.)
and characterized by dynamic mechanical analysis (DMA). Results are
summarized in Table 4.
5TABLE 4 Thermal Analysis of Maleimide/Vinyl Ether Die Attach Films
Cure Profile 60 s/200.degree. C. 4 h/175.degree. C. T.sub.g
(.degree. C.) -1 35 Modulus (E') at -65.degree. C. (psi) 421,300
513,900 Modulus (E') at 100.degree. C. (psi) 5,864 23,980
[0114] The materials exhibited moduli below T.sub.g typical of a
low stress adhesive. The materials' moduli at temperatures above
T.sub.g are sufficient to withstand typical wirebonding conditions
without failure.
* * * * *