Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2003-03-11
2004-10-26
Tucker, Philip (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C523S457000, C523S458000, C525S423000, C525S488000, C525S523000, C525S533000, C528S113000, C528S117000, C528S123000, C528S124000, C528S407000, C549S543000, C549S551000, C549S555000
Reexamination Certificate
active
06809130
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to halogen-free, phosphorus-free flame-retardant epoxy resins suitable for use in making printed circuit boards and in semiconductor encapsulation applications.
BACKGROUND OF THE INVENTION
Epoxy resins have the excellent characteristics of moisture, solvent and chemical resistance, toughness, low shrinkage on cure, superior electrical and mechanical resistance properties, and good adhesion to many substrates. The versatility in formulation also make epoxy resins widely applicable industrially for surface coatings, adhesive, painting materials, potting, composites, laminates, encapsulants for semiconductors, and insulating materials for electric devices, etc. o-Cresol formaldehyde novolac epoxy (CNE) is the resin typically employed in the encapsulation of microelectronic devices. Several approaches for modification of epoxy backbone for enhancing the thermal properties of epoxy resins have been reported. Aromatic bromine compounds in conjunction with antimony oxide are widely used as a flame retardant for epoxy resins. Tetrabromobisphenol A is a typical example of the aromatic bromine compounds used as a flame retardant for epoxy resins. An excess amount of epoxy resin is reacted with tetrabromobisphenol A to prepare an advanced epoxy resin having two terminal epoxide groups, as shown in the following formula:
wherein EP is a bi-radical group of the backbone of the epoxy resin, and m is an integer of 1-10. The advanced epoxy resin can be used in preparing a flame-retardant printed circuit board (FR-4) by impregnating glass fibers with the advanced epoxy resin and heating the resulting composite to cure the advanced epoxy resin. Furthermore, the advanced epoxy resin can be employed to encapsulate microelectronic devices, in which the advanced epoxy resin is cured at a high temperature with a curing agent, so that an encapsulant having a flame-retardant property is formed.
Although the tetrabromobisphenol A-containing advanced epoxy resin shows flame retardant property, major problems encountered with this system are concerned with the generation of toxic and corrosive fumes during combustion such as dioxin and benzofuran.
The flame retardant having a small molecular weight tends to degrade the mechanical properties of the epoxy resins, and migrate/vaporize from the epoxy resins such that the flame retardancy thereof diminishes.
Owing to organic phosphorus compounds generate less toxic gas and smoke than halogen-containing compounds, some authors have reported advanced epoxy resins containing phosphorus compound, for examples U.S. Pat. Nos. 6,291,626; 6,291,627; and JP 2001-220427.
Although phosphorus-containing flame retardants can replace the conventional halogen-containing flame retardants in the aspect of flame retardancy, the phosphorus-containing flame retardants inevitably cause the eutrophication in rivers and lakes after hydrolysis, and create environmental problems. Further, their high absorbency of moisture leads to decomposition, and thus will jeopardizes the long time reliability of a semiconductor product. Therefore, there is a need in the semiconductor product encapsulation industry for developing a halogen-free, phosphorus-free flame-retardant epoxy resin.
SUMMARY OF THE INVENTION
The invention of the present application provide a halogen-free, phosphorus-free flame-retardant advanced epoxy resin, and epoxy composition. They are suitable for use in the fabrication of printed circuit boards and as an encapsulation material for semiconductor products.
The halogen-free, phosphorus-free flame-retardant advanced epoxy resin synthesized according to the present invention has the following formula (I):
wherein Q is
0<n<60; and
Ep is
wherein 0<m<12; 0<p<12; R
1
is hydrogen or methyl; and X=A or B, and at least one of X is B, wherein
The halogen-free, phosphorus-free flame-retardant epoxy composition disclosed in the present invention comprises 10~50 wt % of an epoxy resin having two or more epoxide functionalities; 10~40 wt % of an inorganic filler; and 20~80 wt % of the advanced epoxy resin (I).
Preferably, Q in the formula (I) is methylene.
REFERENCES:
patent: 5179220 (1991-12-01), None
Abstract of Japanese Pat. JP5179220, Derwent, 1993.
Chiou Kuo-Chan
Huang Jia-Chi
Lee Tzong-Ming
Liao Lu-Shih
Lin Tzu-Ting
Aylward D.
Bacon & Thomas PLLC
Industrial Technology Research Institute
Tucker Philip
LandOfFree
Halogen-free, phosphorus-free flame-retardant advanced epoxy... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Halogen-free, phosphorus-free flame-retardant advanced epoxy..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Halogen-free, phosphorus-free flame-retardant advanced epoxy... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3320722