Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2000-09-28
2002-09-17
Hampton-Hightower, P. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C528S026000, C528S028000, C528S038000, C528S125000, C528S126000, C528S128000, C528S172000, C528S173000, C528S176000, C528S179000, C528S183000, C528S185000, C528S220000, C528S229000, C528S350000, C528S351000, C528S353000, C525S420000, C525S422000, C525S431000, C525S474000
Reexamination Certificate
active
06451955
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a method of reacting a dianhydride and a diamine in a low-boiling solvent to make a polyimide. In particular, it relates to preparing a polyimide by slowly adding one of the monomers to a solution of the other monomer in a low-boiling, solvent that is heated to a temperature sufficient to fully imidize polyamic acid as soon as it is formed.
In chip scale packaging, semiconductor dies are attached to FR4 or BT substrates using a solution of a polyimidesiloxane adhesive. A temperature below 150° C. must be used to protect delicate electronic components. To achieve adhesion below 150° C., the solvent in the solution of the polyimidesiloxane adhesive must be removable at a temperature below 150° C., which means that solvents such as N-methyl pyrrolidinone (NMP), which boils at 202° C., cannot be used.
A polyimidesiloxane is made by reacting a dianhydride with a diamine in a solvent, forming an intermediate polyamic acid. That reaction will occur at room temperature. The solution of the polyamic acid is then heated to about 140 to about 150° C. to imidize the polyamic acid. While the intermediate polyamic acid is soluble in polar solvents such as NMP, unfortunately it is not soluble in the low-boiling solvents needed for low temperature adhesive applications, and a gummy precipitate forms. The polyimidesiloxane could be prepared in a high-boiling solvent, such as NMP, precipitated in water, washed, dried, and the solid polyimidesiloxane redissolved in a low-boiling solvent. It would be more convenient, less expensive, and less wasteful, however, to prepare the polyimidesiloxane in the low-boiling solvent and thereby avoid the-extra evaporation and redissolving steps.
SUMMARY OF THE INVENTION
We have discovered a way to prepare a solution of a polyimide in a low-boiling solvent. In our invention, a solution or slurry is first prepared of one of the monomers in the solvent. That solution is heated to about 80 to about 160° C. and the other monomer is slowly added. By preparing the polyimide in this manner, the insoluble polyamic acid intermediate that is formed converts to the soluble polyimide before it can precipitate. Thus, the polyimide can be prepared in the same solvent in which it is to be used and it is not necessary to use one solvent for its preparation and a different solvent for its use.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
This invention is applicable to any polyimide that is soluble in a low-boiling solvent as described herein.
The polyimide can be prepared by reacting an aromatic dianhydride with a diamine. Generally, stoichiometric quantities of diamine and dianhydride are used to obtain the highest molecular weight, but the equivalent ratio of dianhydride to diamine can range from 1:2 to 2:1.
Examples of suitable aromatic dianhydrides include:
1,2,5,6-naphthalene tetracarboxylic dianhydride;
1,4,5,8-naphthalene tetracarboxylic dianhydride;
2,3,6,7-naphthalene tetracarboxylic dianhydride;
2-(3′,4′-dicarboxyphenyl)5,6-dicarboxybenzimidazole dianhydride;
2-(3′,4′-dicarboxyphenyl)5,6-dicarboxybenzoxazole dianhydride;
2-(3′,4′-dicarboxyphenyl)5,6-dicarboxybenzothiazole dianhydride;
2,2′,3,3′-benzophenone tetracarboxylic dianhydride;
2,3,3′,4′-benzophenone tetracarboxylic dianhydride;
3,3′,4,4′-benzophenone tetracarboxyl dianhydride (BTDA);
2,2′,3,3′-biphenyl tetracarboxylic dianhydride;
2,3,3′,4′-biphenyl tetracarboxylic dianhydride;
3,3′,4,4′-biphenyl tetracarboxylic dianhydride (BPDA);
bicyclo-[2,2,2]-octen-(7)-2,3,5,6-tetracarboxylic-2,3,5,6-dianhydride;
thio-diphthalic anhydride;
bis(3,4-dicarboxyphenyl)sulfone dianhydride;
bis(3,4-dicarboxyphenyl)sulfoxide dianhydride;
bis(3,4-dicarboxyphenyl oxadiazole-1,3,4)paraphenylene dianhydride;
bis(3,4-dicarboxyphenyl)2,5-oxadiazole1,3,4-dianhydride;
bis2,5-(3′,4′-dicarboxydiphenylether)1,3,4-oxadiazole dianhydride;
bis(3,4-dicarboxyphenyl)ether dianhydride or 4,4′-oxydiphth alicanhydride (ODPA);
bis(3,4-dicarboxyphenyl)thioether dianhydride;
bisphenol A dianhydride (BPADA);
bisphenol S dianhydride;
2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride or 5,5-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bis-1,3-isobenzofurandione) (6FDA);
hydroquinone bisether dianhydride;
bis(3,4-dicarboxyphenyl)methane dianhydride;
cyclopentadienyl tetracarboxylic acid dianhydride;
cyclopentane tetracarboxylic dianhydride;
ethylene tetracarboxylic acid dianhydride;
perylene 3,4,9,10-tetracarboxylic dianhydride;
pyromellitic dianhydride (PMDA);
tetrahydrofuran tetracarboxylic dianhydride; and
resorcinol dianhydride.
The dianhydrides can be used in their tetraacid form or as mono, di, tri, or tetra esters of the tetra acid, but the dianhydride form is preferred because it is more reactive. The preferred dianhydride is ODPA because it has been found to give excellent properties. Mixtures of dianhydrides are also contemplated. Additional amounts of monoanhydrides or tri- or higher functional anhydrides can be used to control molecular weight or crosslinking.
The diamine used in preparing the polyimide is preferably aromatic as aromatic diamines give the best properties. Examples of aromatic diamines include:
m- and p-phenylenediamine;
2,4-diaminotoluene (TDA);
2,5- and 2,6-diaminotoluene;
p- and m-xylenediamine;
4,4′-diaminobiphenyl;
4,4′-diaminodiphenyl ether or 4,4′-oxydianiline; (ODA)
3,4′-oxydianiline;
4,4′-diaminobenzophenone;
3,3′,3,4′, or 4,4-diaminophenyl sulfone or m,m-, m,p- or p,p-sulfone dianiline;
4,4′-diaminodiphenyl sulfide;
3,3′-diaminodiphenyl sulfone (APS);
3,3′ or 4,4′-diaminodiphenylmethane or m,m- or p,p-methylene dianiline;
3,3′-dimethylbenzidine;
2,2′-bis[(4-aminophenyl)-1,4-diisopropyl]benzene or 4,4′-isopropylidenedianiline or bisaniline P(BAP);
2,2′-bis[(4-aminophenyl)-1,3-diisopropyl]benzene or 3,3′-isopropylidenedianiline or bisaniline M;
methylene dianiline;
1,4-bis(4-aminophenoxy)benzene;
1,3-bis(4-aminophenoxy)benzene;
1,3-bis(3-aminophenoxy)benzene (APB);
4,4′-bis(4-aminophenoxy)biphenyl;
2,4-diamino-5-chlorotoluene;
2,4-diamino-6-chlorotoluene;
2,2-bis-[4(4-aminophenoxy)phenyl]propane (BAPP);
trifluoromethyl-2,4-diaminobenzene;
trifluoromethyl-3,5-diaminobenzene;
2,2-bis(4-aminophenyl)-hexafluoropropane (6F diamine);
2,2-bis(4-phenoxy aniline)isopropylidene;
2,4,6-trimethyl-1,3-diaminobenzene;
4,4′-diamino-5,5′-trifluoromethyl diphenyloxide;
3,3′-diamino-5,5′-trifluoromethyl diphenyloxide;
4,4′-trifluoromethyl-2,2′-diamino biphenyl;
2,5-dimethyl-1,4-phenylenediamine (DPD);
2,4,6-trimethyl-1,3-diaminobenzene;
diaminoanthraquinone;
4,4′-oxybis[(2-trifluoromethyl)benzeneamine] (1,2,4-OBABTF);
4,4′-oxybis[(3-trifluoromethyl)benzeneamine];
4,4′-thiobis[(2-trifluoromethyl)benzeneamine];
4,4′-thiobis[(3-trifluoromethyl)benzeneamine];
4,4′-sulfoxylbis[(2-trifluoromethyl)benzeneamine];
4,4′-sulfoxylbis[(3-trifluoromethyl)benzeneamine];
4,4′-ketobis[(2-trifluoromethyl)benzeneamine];
4,4′-[(2,2,2-trifluoromethyl-1-(trifluoromethyl)-ethylidine)bis(3-trifluoromethyl)benzeneamine]; and
4,4′-dimethylsilylbis[(3-trifluoromethyl)benzeneamine].
The preferred aromatic diamine is APB as it gives excellent properties. Mixtures of aromatic diamines are also contemplated. Additional amounts of monoamines or tri- or higher functional amines can be used to control molecular weight or crosslinking.
The polyimide is preferably a polyimidesiloxane because a polyimidesiloxane has better solubility in the low-boiling solvents used in this invention. To prepare a polyimidesiloxane, a diamine or dianhydride that contains siloxane groups is included as part of the diamine or the dianhydride. A polyimidesiloxane can be made from abo
Choi Jin-O
Hausladen Michael C.
Baker & McKenzie
Flaim John G.
Hampton-Hightower P.
Sumitomo Bakelite Company Limited
Trice Ronald D.
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