Cleaning and liquid contact with solids – Processes – For metallic – siliceous – or calcareous basework – including...
Reexamination Certificate
1998-10-23
2001-03-06
Markoff, Alexander (Department: 1743)
Cleaning and liquid contact with solids
Processes
For metallic, siliceous, or calcareous basework, including...
C134S016000, C134S017000, C134S029000, C134S030000
Reexamination Certificate
active
06197122
ABSTRACT:
TECHNICAL FIELD
This invention is directed to cyclic hydrocarbon compounds which are cured to provide encapsulation and underfill (material under semiconductor chip to spread stress involved in thermal cycling, often on top of a polymer substrate) for electronic components, to curable compositions containing these which may be referred to as uncured thermosets and to the cured compositions which may be referred to as cured thermosets.
BACKGROUND OF THE INVENTION
The compounds of choice, before the invention herein, for providing curable thermosets, have been cycloaliphatic diepoxides containing a primary oxycarbonyl linkage and these have been generally formulated with anhydride curing agent, initiator and catalyst for thermal curing to provide an insoluble, infusible cured thermoset. The compounds have low viscosity and are therefore easily manipulated in the uncured state. The cured compositions adhere well to electronic components, have good durability, provide good insulation of adjacent metal lines from each other, provide good vibration and shock resistance, and have low moisture absorption characteristic. The disadvantage of the cured compositions is their intractability. They are very difficult or impossible to remove from microelectronic assemblies. Their decomposition temperatures are very high.
With the increase in chip size and the common employment of multiple chip modules and the increased cost of the electronic packaging, it has become desirable to recover operative components from assemblies which are inoperative. This is not practical where the compounds now in commercial usage are the basis for the cured compositions which provide encapsulation and underfill for the components. The very high decomposition temperatures of the cured compositions exclude thermal decomposition as a practical method for removing encapsulation and underfill composed of the cured compositions.
Thus, there has been an ongoing search for resins for providing cured thermosets for encapsulation and underfill for electronic components that will allow repair, replacement, recovery or recycling of operative electronic components from assemblies which have become inoperative. The cured thermoset which is being sought is referred to in the art as being “reworkable.”
SUMMARY OF THE INVENTION
It has been discovered herein that a substantial decrease in decomposition temperature for a cured thermoset is obtained by basing the curable composition on compound containing substituted cyclic hydrocarbon moieties linked by moiety comprising a weakened ester linkage compared to the primary oxycarbonyl linkage in present commercially used compounds and in particular by novel compounds utilizing as a linking moiety one containing a secondary or tertiary oxycarbonyl group, and that the curable compositions based on the novel compounds are curable at temperatures where the novel compounds are stable and that the cured thermosets made with these novel compounds retain the advantageous insulation and mechanical properties of the present commercial cured thermosets but have the advantage of being thermally decomposable at relatively low temperatures to residue which is removable from electronic components by common basic solvents, without damaging the electronic components and are reworkable thermosets with all of the characteristics being sought.
These novel compounds contain two cyclic hydrocarbon moieties which are substituted to provide crosslinking functionality, for example, with epoxy group or cyanate group, and which are linked to each other by a secondary or tertiary oxycarbonyl containing moiety, and preferably have the structural formula
wherein each Q is the same or different and is selected from the group consisting of
wherein each R is independently selected from the group consisting of hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert butyl, C
1-4
alkoxy, halogens, cyano, nitro, and phenyl, and R
3
and R
4
together form an epoxy group
and Q″ is
and n is 0 and p is 0 and r is 1, or n is 1 and p is 1 and r is 1 or Q″ is a bond between O and Q and n is 0 and p is 0 and r is 1 or n is 1 and p is 0 and r is 1, or Q″ is
and n is 0 and p is 0 and r is 1, or Q″ is
and p is 1 and n is 1 and r is 0 and t is 1 or p is 0 and n is 1 and r is O and t is O, and R
1
and R
2
are each independently selected from the group consisting of hydrogen, methyl, ethyl, propyl, and phenyl, except that at least one of R
1
and R
2
is not hydrogen, and and p and r are 1, or when Q″ is
compounds are symmetrical; or wherein each Q is the same or different and comprises an aromatic group independently selected from the group consisting of phenyl, biphenyl, and naphthyl, substituted at one position with a functional group selected from the group consisting of cyanate, methacrylate, acrylate, epoxymethoxy, acetylene and maleimide groups and having at each other position substituent independently selected from the group consisting of hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert butyl, C
1-4
alkoxy, halogens, cyano, nitro and phenyl with the functional group of both Q's being the same and Q″ is —C(R
7
) (R
8
)— or
wherein each R
7
and R
8
is independently selected from the group consisting of hydrogen, methyl, ethyl, propyl and phenyl, except that at least one of R
7
and R
8
in at least one —C(R
7
) (R
8
)— is not hydrogen, and Q
2
is phenyl having at each open position substituent independently selected from the group consisting of hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert butyl, C
1-4
alkoxy, halogens, cyano, nitro and phenyl, and p is 0 and n is 0 and r is 1.
One important class of the novel compounds herein, hereinafter Class I, has the structural formula
where each R is independently selected from the group consisting of hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert butyl, C
1-4
alkoxy, halogens, cyano, nitro, and phenyl, and R
3
and R
4
together form an epoxy group, and R
1
and R
2
are each independently selected from the group consisting of hydrogen, methyl, ethyl, propyl, and phenyl, except that at least one of R
1
and R
2
is not hydrogen, and n is 0 and p is 0 and m is 0 or 1.
Another important class of the novel compounds herein, hereinafter Class II, has the structural formula
where R, R
1
, R
2
, R
3
, and R
4
are as defined above and m is 1 and p is 1 and n is 1 or p is 0 and m is 0 and n is 1, and the compounds are symmetrical.
Still another important class of the novel compounds herein, hereinafter Class III, have the structural formula
where R is defined as above and the compounds are symmetrical (i.e., the same substituents R are present in each ring in the same positions).
Still another important class of the novel compounds herein, hereinafter Class IV, have the structural formula
wherein R, R
1
and R
2
are defined as above and c and d are both 1 or c and d are both 0 and the compounds are symmetrical (i.e., the same substituents R are present in each ring in the same positions and both of the R
1
substituents are the same and both of the R
2
substituents are the same).
Still another important class of the novel compounds herein, hereinafter Class V, have the structural formula
where each Q
1
is the same or different and comprises an aromatic group independently selected from the group consisting of phenyl, biphenyl, and naphthyl, substituted at one position with functional group selected from the group consisting of cyanate, methacrylate, acrylate, epoxymethoxy, acetylene and maleimide groups, with the functional groups of both Q
1
's being the same, and having at each other position substituent independently selected from the group consisting of hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert butyl, C
1-4
alkoxy, halogens, cyano, nitro and phenyl and each R
7
and R
8
is independently selected from the group consisting of hydrogen, methyl, ethyl, propyl, and phenyl, except that at least one R
7
or R
8
is not hydrogen, and Q
Koerner Hilmar
Ober Christopher K.
Cornell Research Foundation Inc.
Markoff Alexander
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