Stock material or miscellaneous articles – Composite – Of silicon containing
Reexamination Certificate
2001-02-23
2002-10-08
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Composite
Of silicon containing
C428S473500, C427S387000, C525S431000, C525S440030, C528S028000, C528S038000, C528S068000
Reexamination Certificate
active
06461738
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a polyimide-based insulating film composition, an insulating film and an insulating film-forming method, and more specifically, it relates to a polyimide-based insulating film composition comprising a soluble polyimidosiloxane and a polyvalent isocyanate (polyvalent isocyanate compound), an insulating film and an insulating film-forming method.
The polyimide-based insulating film composition of the invention has satisfactory storage stability (relatively low viscosity is consistently maintained over long periods) and printing properties, and its cured films exhibit satisfactory adhesive properties and solvent resistance.
The insulating film (cured film) of the invention has suitable adhesive properties onto substrates, flex resistance and electrical properties while also exhibiting heat and moisture resistance (PCT), and can be used as an electrically insulating protective film.
When the polyimide-based insulating film composition of the invention is coated onto a silicon wafer, flexible wiring board or the like as a solution composition and then dried and cured to form a protective film, substantially no curling occurs and the protective film exhibits excellent flex resistance and heat resistance as well as adhesion to the substrate, while no pretreatment of the substrate with an adhesion promoter such as a silane coupling agent is required; it can therefore form an excellent protective film.
2. Description of the Related Art
The use of aromatic polyimides, epoxy resins and the like as electrically insulating protective films, for the purpose of providing insulating films for solid elements, semiconductor integrated circuits, flexible wiring boards and the like, has been known to the prior art.
Epoxy resins have plating resistance and satisfactory adhesive properties for substrates, and are therefore used in epoxy dams and the like, but when they are used as insulating films, there have been drawbacks such as rigidity, poor flexibility and impaired bending properties of the insulating films formed by thermosetting.
Aromatic polyimides are generally poorly soluble in organic solvents and therefore must be used as solutions of the aromatic polyimide precursors (aromatic polyamic acids) to form coating films, which are then subjected to prolonged heat treatment at high temperature for drying and imidation to form the aromatic polyimide protective films; this, however, results in the drawback of thermal deterioration of the electrical or electronic members being protected.
On the other hand, aromatic polyimides that are soluble in organic solvents are known, such as aromatic polyimides obtained by polymerization and imidation of biphenyltetracarboxylic acid components and diamine compounds in organic polar solvents such as described, for example, in Japanese Examined Patent Publication No. 57-41491, but these polyimides have exhibited insufficient adhesion (adhesive properties) with silicon wafers, glass plates, flexible boards and the like, and have therefore required pretreatment of the substrates with adhesion promoters.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to provide a polyimide-based insulating film composition with satisfactory storage stability (relatively low viscosity consistently maintained over long periods) and printing properties, whose insulating films (cured films) exhibit satisfactory solvent resistance and adequate balance between heat resistance and flexibility, as well as an insulating film and insulating film-forming method.
In other words, the present invention provides a polyimide-based insulating film composition that comprises (a) 100 parts by weight of an organic solvent-soluble polyimidosiloxane obtained from a tetracarboxylic acid component and a diamine component comprising 45 to 90 mole percent of a diaminopolysiloxane represented by the following general formula (1):
H
2
N—R
1
—[Si(R
2
)
2
—O—]
n1
—Si(R
2
)
2
—R
1
—NH
2
(1)
wherein R
1
represents a divalent hydrocarbon group or a phenyl group, R
2
each independently represents an alkyl group of 1 to 3 carbon atoms or a phenyl group, and nl represents an integer of 3 to 30, 0.5 to 40 mole percent of a polar group-containing aromatic diamine and 0 to 50 mole percent of an aromatic diamine with plural benzene rings, (b) 2 to 40 parts by weight of a polyvalent isocyanate and (c) an organic solvent.
The invention further provides a polyimide-based insulating film obtained by coating a substrate with the aforementioned polyimide-based insulating film composition and then heat-treating it.
The invention still further provides a polyimide-based insulating film-forming method whereby the aforementioned polyimide-based insulating film composition is coated onto a substrate and then heat treated at 50 to 200° C., and preferably 120 to 160° C.
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will now be explained.
1) The aforementioned polyimide-based insulating film composition wherein the polar group-containing aromatic diamine is represented by the following general formula (2):
H
2
N—Bz(r
1
)
n2
Y[XBz(r
1
)
n2
]
n3
—NH
2
(2)
wherein Bz represents a benzene ring, X and Y each independently represent a direct bond, CH
2
, C(CH
3
)
2
, C(CF
3
)
2
, O, Bz or SO
2
, r
1
represents COOH or OH, n2 represents 1 or 2, and n3 represents 0, 1 or 2 but preferably 1.
2) The aforementioned polyimide-based insulating film composition wherein the polycyclic aromatic diamine with plural benzene rings is represented by the following general formula (3):
H
2
N—[BzX]
n4
Y[XBz]
n4
—NH
2
(3)
wherein Bz represents a benzene ring, X and Y each independently represent a direct bond, Bz, CH
2
, C(CH
3
)
2
, O or SO
2
, and n4 is 1 or 2).
3) The aforementioned polyimide-based insulating film composition wherein the inherent viscosity of the polyimidosiloxane (0.5 g/100 ml) is 0.05 to 3.
4) The aforementioned polyimide-based insulating film composition which further comprises (d) a microfiller.
5) The aforementioned polyimide-based insulating film composition wherein the proportion of each component to (a) 100 parts by weight of the polyimidosiloxane is (b) 2 to 40 parts by weight of the polyvalent isocyanate, (c) 50 to 200 parts by weight of the solvent and (d) 20 to 150 parts by weight of the microfiller.
The polyimidosiloxane of the invention may be obtained, for example, by reacting a tetracarboxylic acid component with a diamine component comprising 45 to 90 mole percent of a diaminopolysiloxane, 0.5 to 40 mole percent of a polar group-containing aromatic diamine and 0 to 50 mole percent of at least one aromatic diamine with plural benzene rings to prepare a polyamic acid, and then imidating it. Alternatively, the step of preparing the amic acid may be omitted, and imidation carried out in one step at a relatively high temperature.
The reaction between the tetracarboxylic acid component and the aromatic diamine component may be carried out by random or block reaction or a combination of two or more different homogeneous reactions (with rebonding reaction depending on the case). The polyimidosiloxane reaction product may also be used directly without separation from the solution.
According to the invention, the proportion of the diaminopolysiloxane contained in the diamine component is 45 to 90 mole percent, the proportion of the polar group-containing aromatic diamine component is 0.5 to 40 mole percent and the proportion of the aromatic diamine component with plural benzene rings is 0 to 50 mole percent, in the polyimidosiloxane component. The component proportions are preferably not higher or lower than these ranges, because this may cause a reduction of the curvature radius of the protective film, thus lowering the flex resistance, lowering of the adhesion and heat resistance, and reduction in the moisture resistance.
As tetracarboxylic dianhydrides there may be mentioned aromatic tetracarboxyl
Ichikawa Musubu
Ishikawa Seiji
Dawson Robert
Feely Michael J
Schnader Harrison Segal & Lewis LLP
Ube Industries, Inc.
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