RU2617494C1 - Polymer composition for sealing integrated circuits - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: polymer composition comprises 27.3-28.1% by weight binder - ortho krezolnovolachnoy epoxy resin having a softening point 50-65°C - the polycondensation product of ortho-cresol with paraformaldehyde in an equimolar ratio at first in the presence of oxalic acid to achieve 35-. 45% conversion, then in the presence of p-toluenesulfonic acid to complete the reaction and then reacting the resultant product with epichlorohydrin in an alkaline environment - 13.5-13.8% by weight of curing agent -. novolac phenolic resin grade SF-015, fillers including silica ground powdered 34.8-46.4 wt %, technical carbon 0.60-0.64 wt % of boron nitride and hexagonal 10.1-22.3 wt %, 0.35-0.47 wt % lubricant - oxidized polyethylene wax, 0.1-0.2 wt % coupling agent -. glycidyloxypropyltrimethoxysilane and 0.4-0.61% by weight latent accelerator - complexes of triphenylphosphine with copper chloride or cobaltous dichloride.

EFFECT: invention provides a polymer composition with a controlled viscosity increase in the high temperature homogenization on the rollers, and curing with uniform increased shelf life.

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Description

The invention relates to the production of composite materials based on epoxy and epoxyphenol resins used in the electrical and electronic industry for sealing integrated circuits.

Currently, in foreign and domestic publications related to the development of materials for a similar purpose based on an epoxy binder and phenol-formaldehyde resin as a hardener, triphenylphosphine (TPP) is often used as a curing accelerator.

For example, the company Sumitomo Bakelite Co. developed epoxy compositions for semiconductor seals containing:

- at least 8% of a mixture of two epoxy resins of different structures of 20-80% each (one of which is ortho-cresolobolacia);

- at least 20% phenolic hardener (calculated on the binder);

- 85-92% wt. (to the total weight of the composition) of inorganic fillers and target additives (in particular, a mixture of fused silica, carbon black, carnauba wax);

- curing accelerator, which is used triphenylphosphine (0.2 g).

A piece of sample material has a spiral flow of 80 mm (Korean application KR 9700092, C08L 63/00, publ. 1997; Chemical Abstracts, Volume 123, Ref. 259312b).

Mitsubishi Denki K.K. and Shin-Etsu Chem. Co. Ltd. The proposed composition of the material for sealing electronic devices, including an epoxy resin, preferably epoxycryosolate), a crosslinking agent (preferably phenolic wave resin) and an inorganic filler in an amount of not less than 70%. At the same time, at least one epoxy resin and / or one crosslinking agent have a molecular weight distribution Mw / Mn of less than 1.6. The composition according to example E7 described in the description of the invention, based on ortho-cresol-epoxy with a softening temperature of 72 ° C and Mw / Mn of 1.41 in combination with a phenolic wave resin with a softening temperature of 98 ° C and Mw / Mn of 1.24, also contains brominated epoxyphenolic novolak, filler (fused silica with three different particle sizes: 10 μm - 20% wt., 30 μm - 75% and 0.5 μm - 5%) mixed with soot and target additives - flame retardant, wax, sizing and accelerator curing - triphenylphosphine in the amount of 0.8 wt.h. per 100 parts by weight mixture of resins (European application EP 955675, H01L 23/29, publ. 1999).

Russian patent RU 2447093, C08G 59/08, publ. 04/10/2012, protects the method of producing a binder and a polymer composition based on it for sealing semiconductor devices, including the resulting binder - ortho-cresol-tin resin with a softening temperature of 50-65 ° C - the product of polycondensation of ortho-cresol with paraformaldehyde in an equimolar ratio, first in the equimolar ratio the presence of oxalic acid to achieve 35-45% conversion, then in the presence of paratoluenesulfonic acid until the reaction is completed and the resulting product interacts with epichlorohydrin in an alkaline medium (25 , 0-27.0% wt.), Hardeners - phenolic novolac resin brand SF-015 (12.5-13.5% wt.) And N, N'-dimethyl-3-chlorophenylurea (0.06-0, 08% wt.), Ground quartz (32.0-35.0% wt.), Sizing with glycidyloxypropyltrimethoxysilane (0.29-0.70% wt.), Oxidized polyethylene wax (0.36-0.40% wt. ), carbon black (0.62-0.68% wt.), hexagonal boron nitride (22.1-27.6% wt.) and triphenylphosphine accelerator (0.2-0.4% wt.)

The advantages of using triphenylphosphine as an accelerator are its high activity at a low content in the composition, however, its presence in the compositions reduces the storage time of the material at room temperature (2-3 months), which necessitates the storage of the material in the refrigerator. In the manufacture of the press material, all components of the composition are homogenized in the melt on the rollers at a temperature of 95-110 ° C, the residence time of the material on the rollers is 1-2 minutes. During this time, the epoxy resin has time to partially interact with the phenolic resin under the action of triphenylphosphine, which leads to an undesirable increase in the viscosity of the melt of the final product. With the introduction of triphenylphosphine after homogenization in the melt, its powder distribution is uneven and, as a result, uneven curing, the presence of areas with a low degree of cure, leading to a decrease in the chemical resistance of the material.

Known epoxy compositions for encapsulating semiconductor devices (US patent US 6194491, C08K 3/36, publ. 02.27.2001, including:

- biphenyl type epoxy resin 100 parts by weight,

- a crosslinking agent introduced in an amount of 0-100 parts by weight, preferably 5-95 parts by weight,

- a crosslinking accelerator, which is a product of the additive interaction (adduct) of triphenylphosphine and p-benzoquinone, obtained, for example, by dissolving the starting components in a ketone medium (methyl isobutyl ketone, methyl ethyl ketone, acetone, etc.) and stirring at a temperature from room temperature to 80 ° C within 1 to 12 hours .; its content in the composition is 0.1-10 parts by weight, preferably 0.5-7 parts by weight;

- inorganic filler - 85-95 wt. % (based on the weight of the composition), and the amount of crosslinking agent is preferably from 1 to 1.4 equivalents per 1 equivalent of epoxy resin;

- targeted supplements.

In accordance with example 1, a mixture of two epoxy resins was used, one of which was brominated (85 parts by weight of biphenyl epoxy and 15 parts by weight of brominated), 93 parts by weight a crosslinking agent, 3 parts by weight crosslinking accelerator, carnauba wax (1.0 parts by weight), polyethylene wax (0.5 parts by weight), carbon black (3.5 parts by weight), antimony trioxide (6.0 parts by weight), glycidoxypropyltrimethoxysilane (7.5 parts by weight) and spherical molten silica with a particle size of 30 μm (2000 parts by weight).

The material according to the US patent has a narrow purpose: to encapsulate the outer lattices of rockets, and the skin of the rockets should have a bimetallic structure, for which it is necessary to reduce the warpage between the substrate and the skin. Compositions in accordance with the patent have a warpage of 19-80 μm versus 95-170 for known compositions. In this case, the spiral yield value is 30-35 inch.

For most of the main (binder, hardener, main filler and total content of fillers) matching characteristics and the purpose of the composite material, the Russian patent RU 2447093 considered above containing triphenylphosphine as a curing accelerator was adopted as a prototype.

The technical task of the invention is to develop a polymer composition, characterized by a controlled increase in viscosity during high-temperature homogenization on the rollers, uniform curing and increased shelf life.

The problem is solved in that the polymer composition for sealing integrated circuits, including a binder - ortho-cresol-wave epoxy resin with a softening temperature of 50-65 ° C - is the product of polycondensation of ortho-cresol with paraformaldehyde in an equimolar ratio, first in the presence of oxalic acid until 35-45% is reached conversion, then in the presence of paratoluenesulfonic acid until the reaction is completed and subsequent reaction of the obtained product with epichlorohydrin in an alkaline medium - hardener - phenolic novol SF-015 grade resin, fillers - powdered quartz, industrial carbon and hexagonal boron nitride, grease - oxidized polyethylene wax, coupling agent - glycidyloxypropyltrimethoxysilane and triphenylphosphine latent accelerator, contains an accelerator in the form of complex compounds of triphenylphosphine with dichloride and chloride to chloride components of the composition, wt. %:

epoxy resin 27.3-28.1 phenolic novolac resin brand SF-015 13.5-13.8 powdered quartz 34.8-46.4 carbon technical 0.60-0.64 hexagonal boron nitride 10.1-22.3 oxidized polyethylene wax 0.35-0.47 glycidyloxypropyltrimethoxysilane 0.10-0.20 complex of triphenylphosphine with copper chloride or with cobalt dichloride 0.4-0.61

We synthesized complexes of triphenylphosphine with copper chloride or cobalt dichloride by direct interaction of equimolecular amounts of triphenylphosphine with copper (I) chloride or cobalt (II) chloride hexahydrate in a solvent, in particular, acetonitrile, at a temperature of 70-75 ° C with a yield of 80-85%.

We have not identified any publications on the use of these complexes as accelerators of the curing process of epoxy resins. In particular, in the description of the patent US 6500564, publ. 12/31/2002, triphenylphosphines, tributylphosphines, tri (p-methylphenyl) phosphines, tri (nonylphenyl) phosphines, diphenyltolylphosphines and a salt of triorganoforane-triphenylphosphine triorganophosphines are mentioned as examples of organophosphine catalysts for crosslinking epoxy resins.

The use of the well-known complex of triphenylphosphine with benzoquinone to accelerate the crosslinking of an epoxy resin with a compound containing one or more phenolic hydroxyl groups, mentioned in general terms in the description of patent US 6194491, filed October 5, 1998 (priority October 3, 1997) does not solve our problem - does not ensure stability of the viscosity of the composition during homogenization of the composition in the melt: an increase in viscosity takes place, although to a lesser extent compared to pure triphenylphosphite. To evaluate this effect, we specially synthesized a complex of triphenylphosphite with benzoquinone by their interaction in ethanol at a temperature of 5 ° C in accordance with a later publication - September 2004 “Kinetic study of triphenylphosphine addition to para-benzoquinone”. International Journal of Kinetics, Vol 36, Issue 9, pages 472-479. The yield in this case is about 40%, and the cost of benzoquinone significantly exceeds the cost of the copper chlorides and cobalt hexahydrate obtained by us.

The invention is illustrated by examples 1-5 and control example 6.

Example 1

Obtaining a binder: in accordance with Example 2 of RU 2447093, an ortho-cresol-wave epoxy is obtained by reacting 1 mol (108 parts by weight) of ortho-cresol and 1 mol of paraformaldehyde (28.5 parts by weight) in n-butanol (250 wt. hours) in the presence of 7.0 wt. including oxalic acid at a temperature of 115 ± 2 ° C until a conversion of 35% is reached, followed by a charge of 4 wt. including paratoluenesulfonic acid and holding at the indicated temperature until completion of the reaction. After distillation of butanol and neutralization of the reaction mass with aqueous sodium hydroxide, 370 wt. including epichlorohydrin, cool the reaction mass to 60 ° C and add portionwise 15 wt. including crushed caustic soda with an interval of 30 minutes, maintaining a temperature of 65-70 ° C. After cooling the mixture, 450 ml of chloroform are added, filtered from the resulting crystals of sodium chloride, the solution is washed with warm water and the chloroform is distilled from the separated chloroform layer at 50-120 ° C and a vacuum of 10-20 mm Hg. Get the target product with a softening temperature of 60 ° C.

Obtaining a polymer composition: in a ball mill with ceramic balls placed 27.3% wt. ortho-cresolnovolac epoxy resin, 13.7% wt. phenol-formaldehyde novolac resin SF-015 (GOST 18694-80), previously subjected to purification from free phenol in vacuum at 150 ° C, 35.2% wt. industrially produced powdered quartz powder (KMP grade B), saponified 0.15% wt. glycidyloxypropyltrimethoxysilane, 0.4% wt. complex of triphenylphosphine with copper chloride, 22.3% wt. boron nitride, 0.35% wt. wax oxidized polyethylene and 0.60% wt. technical carbon (soot). Mixing is carried out until a powder passes completely through a 0.5 mm sieve. Next, the powder is homogenized on rollers with electric heating with a shaft diameter of 100 mm, a length of the working part of 200 mm and a gap of 0.5-1.0 mm with a roll temperature of 95-110 ° C for 2 minutes. The material obtained after rolling is re-mixed and sieved through a 0.5 mm vibrating screen. Curing cycle: 100 s at 175 ° C and curing for 1 hour at the same temperature.

The compositions of examples 1-5, control example 6 and example 3 of the composition of the prototype and the characteristics of the materials obtained are presented in the table.

From the information presented in the table, it can be seen that the compositions in accordance with the invention superior to the composition of the prototype in spiral flow by 16-30% with a sufficiently high stability of this indicator during storage: a decrease of 10-12% after 4 months of storage compared with 34% for the prototype, and therefore the regulated shelf life of the composition of the prototype is 3 months.

The proposed composition is technologically advanced, ensuring stability of the viscosity during homogenization in the melt and uniform curing; however, the use of a specific complex in the required amount allows one to obtain compositions with a controlled gelation time in the range of 20-35 s at 175 ° C.

Claims (2)

A polymer composition for sealing integrated circuits, including a binder - ortho-cresol-wolf epoxy resin with a softening temperature of 50-65 ° C - the product of polycondensation of ortho-cresol with paraformaldehyde in an equimolar ratio, first in the presence of oxalic acid to achieve 35-45% conversion, then in the presence of paratoluenesulfonic acid until the reaction is completed and subsequent reaction of the obtained product with epichlorohydrin in an alkaline medium - hardener - phenolic novolac resin brand SF-015, fillers - powdered ground varts, industrial carbon and hexagonal boron nitride, grease - oxidized polyethylene wax, size - glycidyloxypropyltrimethoxysilane and triphenylphosphine latent accelerator, characterized in that it contains an accelerator in the form of complex compounds of triphenylphosphine with copper chloride or cobalt dichloride composition. %: epoxy resin 27.3-28.1 phenolic novolac resin brand SF-015 13.5-13.8 powdered quartz 34.8-46.4 carbon technical 0.60-0.64 hexagonal boron nitride 10.1-22.3 oxidized polyethylene wax 0.35-0.47 glycidyloxypropyltrimethoxysilane 0.10-0.20 complex of triphenylphosphine with copper chloride or with cobalt dichloride 0.4-0.61