Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-07-20
2003-01-14
Moore, Margaret G. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S779000, C523S440000, C523S457000, C106S018260, C106S461000, C423S635000, C423S274000, C428S403000, C428S447000, C428S413000, C428S330000
Reexamination Certificate
active
06506828
ABSTRACT:
DETAILED DESCRIPTION OF THE INVENTION
1. Field of the Invention
The present invention relates to a resin composition, molded products formed therefrom and use thereof. Particularly, it relates to a resin composition having excellent flame retardancy, heat conductivity and water resistance, molded products formed therefrom and use thereof. More particularly, it relates to a resin composition which is suitable for use as a material for sealing a semiconductor and contains substantially no halogen.
2. Prior Art
Semiconductor elements and integrated circuit elements are sealed by sealing materials to protect them from external vibration, impact, dust, water, atmospheric gas and the like. Although metal materials, ceramics, glass and the like have been used as the sealing materials, plastic resins have recently been used in most cases from the viewpoints of cost and mass-productivity.
Epoxy resins, silicone resins, phenolic resins, diallyl phthalate resins and polyimide resins have been used as the sealing materials and obtained satisfactory results.
However, due to a tendency toward higher integration, smaller elements, finer wiring patterns with technical innovation in the filed of semiconductor, packages tend to be smaller and thinner, with result that higher reliability is required of sealing materials.
Further, electronic parts such as semiconductor devices need to be high flame retardant and brominated epoxy resin and antimony trioxide are contained in the sealing materials. However, when antimony trioxide is used, it causes environmental safety problems such as harmfulness to the human body and the corrosion of equipment by hydrogen bromide, bromine-based gas and antimony bromide generated at the time of combustion, industrial waste produced in the step of sealing semiconductor elements and the disposal of semiconductor devices after use.
Further, when a semiconductor device which contains the above flame retardant is left at high temperatures for a long time, an aluminum wiring on a semiconductor element is corroded by the influence of liberated bromine, causing a failure of the semiconductor device and reducing high-temperature reliability. To solve the above problems, there is proposed a method of adding metal hydroxide particles as a flame retardant.
However, as a large amount (40 wt % or more) of a metal hydroxide must be blended in this method, such a problem arises that semiconductor device swells or cracks by the quick vaporization of water absorbed by the metal hydroxide particles which have high water absorption when the semiconductor device is exposed to high temperatures (generally 215 to 260° C.), thereby reducing solder resistance.
The above method involves another problem that the function of a semiconductor element deteriorates under high temperature and high humidity such as at a temperature of 80 to 200° C. and a relative humidity of 70 to 100%.
JP-A 7-806085 (the term “JP-A” as used herein means an “unexamined Japanese patent application”) proposes a thermosetting resin composition for sealing a semiconductor which comprises a thermosetting resin, curing agent, metal hydroxide particles and metal oxide particles. Higher flame retardancy, higher moisture resistance and higher safety are needed due to recent technical innovation made in the semiconductor field. Further, when the metal hydroxide particles and the metal oxide particles contain impurities in large quantities, they cause the corrosion of a mold and semiconductor element.
Problem to Be Solved by the Invention
It is therefore a first object of the present invention to provide a resin composition which has excellent flame retardancy, heat conductivity and water resistance and molded products formed therefrom.
It is a second object of the present invention to provide a flame retardant resin composition which is suitable for use as a material for sealing a semiconductor and contains substantially no halogen and molded products formed therefrom.
It is a third object of the present invention to provide a resin composition which has excellent heat conductivity that it can radiate heat from a heat generating electronic member and molded products formed therefrom.
Means for Solving the Problems
It has been found by studies conducted by the inventors of the present invention that the above objects of the present invention are attained by selecting magnesium oxide particles which have a specified secondary particle diameter and a specified BET method specific surface area, contain a Fe compound and an Mn compound in predetermined amounts or less and have extremely small contents of Na and Cl, as magnesium oxide particles to be composed into a synthetic resin.
That is, according to the present invention, there is provided a resin composition which comprises 100 parts by weight of a synthetic resin and 50 to 1,500 parts by weight of magnesium oxide particles, wherein
the magnesium oxide particles satisfy the following requirements (i) to (v):
(i) an average secondary particle diameter of 0.1 to 130 &mgr;m,
(ii) a BET method specific surface area of 0.1 to 5 m
2
/g,
(iii) a total content of an Fe compound and an Mn compound of 0.01 wt % or less in terms of metals,
(iv) an Na content of 0.001 wt % or less, and
(v) a Cl content of 0.005 wt % or less.
The present invention will be described in detail hereinafter.
The magnesium oxide particles used in the present invention satisfy the following requirements (i) to (v):
(i) an average secondary particle diameter of 0.1 to 130 &mgr;m, preferably 0.5 to 50 &mgr;m,
(ii) a BET method specific surface area of 0.1 to 5 m
2
/g, preferably 0.1 to 3 m
2
/g,
(iii) a total content of an Fe compound and an Mn compound of 0.01 wt % or less, preferably 0.005 wt % or less in terms of metals,
(iv) an Na content of 0.001 wt % or less, preferably 0.0005 wt % or less, and
(v) a Cl content of 0.005 wt % or less, preferably 0.002 wt % or less.
When the magnesium oxide particles have a large total content of an iron compound and a manganese compound, they reduce the thermal stability of the resin considerably. However, when only the total content of the iron compound and the manganese compound falls within the above range, deterioration in the physical properties of the resin cannot be prevented, and the above average secondary particle diameter and specific surface area must fall within the above ranges as well at the same time. As the average second particle diameter of the particles increases, the particles have a smaller contact area with the resin and higher thermal stability but reduced mechanical strength and occurred problems such as a poor appearance.
As described above, when the magnesium oxide particles satisfy the above requirements for average secondary particle diameter, specific surface area, the total content of an iron compound and a manganese compound, Na content and Cl content, there is obtained a resin composition which is satisfactory in terms of characteristic properties such as compatibility with a resin, dispersibility, moldability and workability, the appearance of a molded product, mechanical strength and flame retardancy.
The magnesium oxide particles may be produced by any conventional method. For example, magnesium oxide particles having high fluidity, high loading properties and high hydration resistance are obtained by the method disclosed by JP-A 6-171928, that is, by baking highly dispersible magnesium hydroxide at a predetermined temperature and grinding the baked product to a predetermined particle diameter without destroying the crystals of the baked product substantially and classifying the ground product. The magnesium oxide particles may be and preferably are spherical magnesium oxide particles obtained by granulating and drying a highly dispersible magnesium hydroxide slurry by spray drying and baking the obtained granules at a predetermined temperature.
To ensure that the Fe compound, Mn compound, Na and Cl contents of the magnesium oxide particles should fall within the above ranges, a high-purity Mg raw material and alkali raw material must be
Anabuki Hitoshi
Yokozeki Machiko
Kyowa Chemical Industry Co. Ltd.
Moore Margaret G.
Sherman & Shalloway
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