CS238695B1 - Electric conduction resin for microelectronics - Google Patents

Abstract

Accelerate low molecular weight curing reaction .epoxide resins and aro.- polyemines at reaction temperatures 130 to 200 C. Simultaneously and accelerate curing also shows improvement electrical conductivity of the cured sealant. The accelerators can be used technically Compound compounds which contain hydroxy groups hydrocaromatic or aromatic groups ring, i.e. especially carbocyclic terpene alcohols, their aromatic analogues, polyhydroxybenzenes or cycloaliphatic alcohols. The invention can also be applied to electrically non-conductive devices of sealants and composites in microelectronics also in other fields.

Description

The invention relates to the acceleration of the high-temperature curing of epoxy electrically conductive sealants for microelectronics.

Electrically conductive sealants are used in the assembly of hybrid integrated circuits, but also in other microelectronics industries. These sealants, deposited on a suitable substrate by screen printing, stamping, syringe or simply stick, are charged with various chips or piezocrystals, which after curing of the sealant is contacted with gold wire or otherwise finished. The bonding agent in microelectronic sealants is most often epoxy resin cured by aromatic polyamine hardeners at elevated curing temperatures (T _c ). Such a high temperature system has better chemical and thermal resistance than a low temperature system, i.e. a system generally containing aliphatic polyamines. The reaction of the epoxy group with the aromatic amine is slower than the reaction with the aliphatic polyamine, due to the lower bezity and steric hindrance of the aromatic ring. It is therefore recommended to use a curing reaction for these high temperature epoxy acid accelerator systems. Phenols, BFj complexes, some alcohols, carboxylic acids, sulfonic acids, carboxylic anhydrides, amides and some monoalkyl derivatives may serve as accelerators. The filler of electrically conductive sealants is most often metallic silver in the form of flaky particles (so-called flake silver). For practical reasons of increasing the service life, the sealants for microelectronics are mainly formulated as two-component, with component A mainly containing a binder, component B a hardener and other additives.

The present invention addresses the issue of accelerating the curing of epoxy sealants for microelectronics.

As an accelerator of the reaction of a low molecular weight epoxy resin having an epoxy equivalent of from 35 to 315 g / mol ^-1 and an aromatic polyamine, such as e.g. 1,2- or 1,3-benzenediamine, or bia (4-eminophenyl) methane, a mono- or bifunctional alcohol is used in the group of carbocyclic terpenes, their aromatic analogs, or from substantially simpler cycloaliphatic alcohols and polyhydroxybenzenes such as menthol, cervomenthol , terpineol, terpine, thymol, carvacrol, cyclohexanol, methylcyclohexanol, resorcin, etc. If the accelerator is a crystalline substance, it is necessary to use a neutral solvent, e.g. dibutyl phthalate (IEF).

This known plasticizer dissolves the crystalline accelerator, including the crystalline hardener, and together with the metallic silver forms a pasty mixture, commonly referred to as component B. When the accelerator is liquid (terpineol, methylcyclohexanol, etc.), it acts as a plasticizer and solid component in component B.

The composition of the individual components of the two-lined sealant ae is within the following limits: Component A contains 50-80 ha of flake silver and 50-20% by weight of the above-mentioned low molecular weight epoxy resin. Component B consists of <5-80 wt.% Flake silver, 3 24 wt.% Aromatic polyamine, 17-24 wt.% Accelerator, and 0-9.25 wt.% Dibutyl phthalate.

The components A and B, when mixed in the required ratio, give a paste having a suitable viscosity for the application method. The curing, which takes place at temperatures from 130 to 200 ° C, can be continuously monitored by means of the ohmaetrea registration process. If the deposited mixture is still liquid, then it does not conduct current, it has an electrical resistance B «and the recorder pen is in the rightmost position. At the time t _a , measured from the moment of the test sample being placed on the hotplate, there is an embryo of the epoxy matrix spatial structure, in which the silver foil ae particles come into contact with each other and simultaneously conduct an electric current (after time t *) The resulting three-dimensional gel (gel) ae is improved during the first tens of seconds such that after 5 - 10 minutes from the start of curing the further decrease in electrical resistance is slight.

The invention is further illustrated by the following non-limiting examples.

Example 1

Component A is prepared by dispersing 75 parts of flake silver in 25 parts of casting epoxy resin, obtained by alkaline condensation of diane with epiehlorohydrin (epoxide groups content 192 g.mol ^-1 ). Component B consists of 75 parts flake silver, 6.75 parts techn. bis (4-aminophenyl) methene (methylenedianiline - MDA) and from 18.25 parts butyl * phthalate (IBF). After mixing the two components in a 1: 1 weight ratio, a 2 x 20 mm (ie 10 squares) rectangular pattern is sieved onto a ceramic substrate; heating plate temperature: T = 150-2 ° C.

Measurement results (average of five samples):

t _# =, 60 e Rj = 25 Ω / 10Π (tg is the start time of the motion of the pistol, resistance after 5 minutes)

Example 2

Component A - see ex., Component B: half of the amount of EBF (in ex. <) Is unhindered by menthol; conditions same as ad 1:

tg = 64 s 1 (5 = 13.7Ω / 100

Example 3

For conditions and component A, see example 1, component B: the IBF (in example 1) is technical terpineol:

_T - 6s 85 = 3.5Ω / 10Π

Example 4

Conditions and component A of visa ex. 1, component B: half of DBF (ex. 1) is replaced by terplneol:

t _g = 42 s Rj = 7.9Ω / 10Π

Example 5

Conditions and Component A of VIS ', component B: two-thirds of the IBF content of Ex 1 is not techn. terplneolem:

tg = 26 s 1 (5 = 6, βΩ / ιθΠ

Example 6

Conditions and composition of both components as in example 1, only IBF is not threatened by citronellol:

t _e e R5 not measurable, the mixture did not show a change in resistance (from B = 00 within 60 minutes)

Example 7

Component A - see example 1, component B as ad 1, only the same quantity of techn. of pure thymol. After melting the mixture of thymol (m.p. 49.7 ° C) and MDA and dispersing flaked silver in this melt, a paste of suitable viscosity for screen printing was formed. However, by day two, component B had increased its viscosity to such an extent that it was necessary to dilute it with 10 wt% IBF and not to weigh for 1 part of component A 1.1 parts of component for screen printing.

T _c = 150 ± 2 ° C:

t _e = 15 and H = 4.0, 5S / 1OD

Example 8

Conditions and composition as in Ex. 1, but a technical mixture of aethylcyclohe4 xanol is used instead of IBF:

These examples show that if the binder is hardened by the presence of a hydroxyl group containing accelerators, the starting time t _# is twenty to forty times and the resistance is five to seven times greater than when the accelerator is present in the binder (except elipetic terpene alcohol-citronellol) ).

The primarily wet structure of the three-dimensional network, e.g., and the low electrical conductivity value of Example 1, cannot be significantly improved, i.e., significantly increased the electrical conductivity of the sample, by longer curing or higher temperature. It is therefore necessary to always use a suitable type of accelerator to achieve the required electrical properties of the cured sealant.

Claims (1)

Electrically conductive sealant for microelectronics, cured at temperatures from 130 to 200 ° C, containing 10 to 25% by weight of low molecular weight epoxy resin with an epoxy equivalent of from 35 to 315 e.mol, 57.5 to 80% by weight of flake silver; 5 to 12% by weight of an aromatic polyamine selected from the group consisting of 1,2-bensenediamine, 1,3-bensenedianine or bis (4-eminophenyl) methene and 0 to 4.6% by weight of dibutyl phthalate, characterized in that it contains 8 curing accelerators 5 to 2% by weight of a compound from the group of kerbocyclic terpenic alcohols or their eromatic analogs or cycloaliphatic alcohols or polyhydroxybenzenes, including menthol, cervomenthol, terplneol, terpline, thymol, carecrole, cyclohexanol, methylcyclohexenol, retorcin.