JPS59147068A - Production of heat-resistant electrically conductive adhesive - Google Patents

Abstract

PURPOSE:To provide the titled adhesive durable at a high temperature, by mixing a specific epoxy resin with vinyl cyclohexene dioxide at a specific ratio, adding a curing agent and a cure accelerator to the mixture to obtain a base res in, and dispersing a specific flaky silver powder to the resin. CONSTITUTION:A diaminodiphenylmethane tetraglycidylamine-type epoxy resin having an apoxy equivalent of 110-130 is mixed with a vinylcyclohexene dioxide having an epoxy equivalent of 70-74 at a ratio of 6:4-5:5. The mixture is mixed with 10-15phr of dicyandiamide as a curing agent, based on the epoxy resin, and 2-3phr, based on the epoxy resin, of 2-phenyl-4-methyl-5-hydroxy- methylimidazole as a cure accelerator, and the additives are dispersed with a roll to obtain a base resin. The objective adhesive can be obtained by adding 68-72wt% of flaky silver powder having a particle diameter of 2.4-3.0mum to the base resin and mixing and dispersing the powder in the resin. EFFECT:The adhesive maintains an adhesivity of >=30kg/cm<2> even after the heat- treatment at 450 deg.C for 1min.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention describes the structure and problems of conventional heat-resistant conductive adhesives that can withstand high temperatures of 450°C. Because the adhesive has low heat resistance, when applied as a guibonding adhesive in the semiconductor industry, if the humidity in the so-called wire bonding process in the post-process exceeds 350°C, the adhesive strength between the chip and the lead frame will decrease. It could not be used for models requiring wire bonding temperatures higher than the above-mentioned temperature. Furthermore, conventionally, cresol novolak type and cresol novolac type epoxy resins have been widely used in order to provide heat resistance. However, when this epoxy resin is used, the viscosity of the resin becomes high, and the low viscosity makes it unnecessary to use solvents, which is inconvenient because foaming occurs due to the solvent scattering when the conductive adhesive hardens. Met.

OBJECTS OF THE INVENTION The object of the present invention is to eliminate such drawbacks and to obtain a conductive adhesive having an adhesive strength of 30 kl/cm2 or more even after heat treatment at 450° C. for 1 minute.

Structure of the Invention The present invention provides diaminodiphenylmethane butraglycidylamine type (structural formula 1) having an epoxy equivalent of 110 to 130.
, hereinafter abbreviated as D D Itll T G A) and epoxy 70 to 74 vinyl, lohexene dioxide (structural formula 2, hereinafter abbreviated as V C! HD O) at 6°
7I~5; Step of mixing in step 5, adding 10 to 15 percent dicyancyamide as a curing agent to the mixture (representing the number of parts added to 100 parts of resin, hereinafter p)
Abbreviated as hr. ) and curing accelerator 2-phenyl-4
- A step of adding 2 to 3 parts of methyl-5-hydroxymedylimidazole to the epoxy resin and dispersing it with a roll to form Haas tree BW, adding the base resin to the base resin with a particle size of 24 to 3.
Add 0 prn of scaly silver powder and 68-72 wt%,
It is characterized by consisting of a mixing and dispersing process.

An example will be explained.

The above structural formula 1.2 is shown below.

Structural Formula 2 The heat-resistant conductive adhesive of the present invention has the above structure. 1
In the configuration of Section 11J, DDMTGA, and V'
CHD O was used because it has four and two functional groups per molecule, respectively, and a cured product with a high crosslink density can be obtained. Further, VCHDO has a viscosity of about io'cps at room temperature, and is useful as a diluent for low viscosity F.

In the present invention, DDMTGA and VOHDO are mixed in a ratio of 6:4 to 5.
5, but if DDMTG'A is used in an amount exceeding this composition range, the viscosity increases and a solvent is required. If less than the above composition range is used, the heat resistance will deteriorate and therefore the adhesive strength will decrease. Dicyandiamide was used as a curing agent for the epoxy resin having the above composition range.
~15 phr, curing accelerator and 2-phenyl-4-methyl-5-hydroxymethylimidazole (hereinafter referred to as 2P4
Abbreviated as MH2 and 1. ) is added in an amount of 2 to 3 phr and thoroughly dispersed using a triple roll to form the base resin of the conductive adhesive. Dicyandiamide was used as a curing agent because dicyandiamide is a latent curing agent and has less time to be used than other acid anhydride curing agents or amine curing agents.
This is because the viscosity of the adhesive can be reduced, and because the epoxy resin is three-dimensionally crosslinked, a heat-resistant cured product can be obtained. Furthermore, although the reason is not clear, dicyandiamide has a higher adhesive strength after high-temperature treatment than other latent curing agents, such as imidazole, and also has a very long pot life of 6 months at 5°C. If the amount of dicyandiamide is less than the above amount, curing will not occur sufficiently and the adhesive strength will decrease.
If the amount exceeds the above-mentioned additive amount, the viscosity will increase and a solvent for lowering the viscosity will be required.

68 to 72 wt% of scaly silver powder with a particle size of 24 to 3.071 m is added to the mixture of -1- below, and mixed and dispersed using a pickling machine to obtain a conductive adhesive. At this time, if the silver powder is less than 68wt%, the conductivity of the adhesive will become unstable, and if the silver powder is less than 68wt%,
% or more, the viscosity becomes high.

The conductive adhesive obtained as above was heated at 150℃ for 3
When cured for 0 to 60 minutes, the volume resistivity is 5×■0
Ω・＞, the adhesive strength between the Si chip and the lead frame is 100 kp/crn2 or more at room temperature and 30 k at 30°C.
i/cm2. Further, when heat-treated at 450° C. for 1 minute after adhering the Si chip to the lead strand, the adhesion strength at room temperature was 30 ky/1 yn 2 . The adhesive strength at 300°C and the adhesive strength after heat treatment at /15°C are both 1 for ordinary Evogin resin-based conductive adhesive.
0 kl/cm2 or less, it can be seen that the heat-resistant conductive adhesive according to the present invention has several times more heat resistance than conventional adhesives. Further, the heat-resistant conductive adhesive according to the present invention has a very long pot life of 6 months at 5° C., even though it is liquid-based.

Example Ediaminodiphenylmethane tetraglycidylamine quive epoxy resin (manufactured by Tobu Kasei Co., Ltd., YHt+34) 5
o parts, 50 parts of vinyl chlorhexene dioxide (manufactured by Unison Carbide Pestle, KRL-4206), 15 parts of dicyandiamide (1 part manufactured by Hon Carbide Co., Ltd.), 2-phenyl-4-methyl-5-hydroxymethylimidazole (Shikoku) Kasei Kogyo Co., Ltd., Curesol 2 P 4 MH
Z) 2 parts are mixed and dispersed using a triple roll.

The obtained composition and scaly silver powder (manufactured by Tsutsuba Kagaku Kenkyusho, TO
G-]) are mixed and dispersed in a crusher at a ratio of 28 parts and 72 parts, respectively, to obtain a conductive adhesive.

Using the obtained conductive adhesive, an IC chip of 2 m and m' was bonded onto a silver-plated lead frame and cured in a hot air circulation dryer at 150°C for 60 minutes. Using a push-pull gauge, the adhesive strength between the chip and the lead frame was measured at room temperature] 30 kjj/1yn2.
It was 30 kfj and 7 cm2 at 300°C.

In addition, the bonded chip and lead frame were heated at 450℃ for 1
After heat treatment for minutes, the adhesion strength was measured at room temperature to 30ky.
/m2, and 350℃, which is not practiced in semiconductor manufacturing.
It has adhesive strength sufficient to withstand wire honting at temperatures up to 450°C. Further, the volume resistivity of the cured product of this conductive adhesive was 5×·-4 10Ω·mm.

Example 2 A conductive adhesive was prepared by mixing and dispersing the epoxy resin and curing agent composition obtained in Example [2] and silver powder (TCG-t) in proportions of 32 parts and 68 parts, respectively, using a pickling machine. get. When the adhesive strength was measured after curing at 150°C for 60 minutes in the same manner as in Example 1, at room temperature it was 150 LCf/saw 2.300°C.
So it was 45 kg, /2.

After heat treatment at 450° C. for 1 minute in the same manner as in Example 1, the adhesive strength at room temperature was 35 ky/(7)2.

Further, the volume resistivity of this cured product was 8×]0 Ω·saw.

Example 3 60 parts of YH434, 40 parts of KRL-4206, 110 parts of dicyanadiazine, and 23 parts of 2P4MH are mixed and dispersed using a triple roll. A conductive adhesive is obtained by mixing and dispersing the obtained composition and scaly silver powder (T, co-t) in a ratio of 32 parts and 68 parts, respectively, in a dispersion machine. Similar to Example 1, when the adhesive strength was measured after curing at 150°C for 60 minutes, at room temperature t 40 ki10n2
．． At 300°C, it was 55kf/cm2. The adhesive strength at room temperature after heat treatment at 450° C. for 1 minute in the same manner as in Example 1 was 45 kl/1yn2. Further, the volume resistivity of this cured product was 6XlO'Ω·m.

More than the effects of the invention, as shown in the examples, by using the conductive adhesive obtained by the present invention, in the semiconductor assembly process,
Wire bonding at high temperatures of 350°C to 450°C, which was previously difficult, is now possible, and more types of chips, lead frames, bonding wires, and sealing methods can be selected.

Patent applicant: Patent attorney representing Matsushita Electric Industrial Co., Ltd.
Isao Abe

Claims (1)

[Claims] Mix 30 diaminodiphenylmethanetetragrindylamine type epoxy resin with epoxy equivalent of 70 to 74 noclohexene dioxide in a ratio of 6:4 to 5:5 1: culm, The mixture was added with dicyandiamide as a curing agent, an IQ of ~15 phr for the epoxy resin, and a curing accelerator of 2-
A step of adding 2 to 3 parts of phenyl-4-methyl-5-hydrogishime, tylimidazole to the epoxy resin and dispersing it with a roll to form a base resin, adding 24 to 3011 nm once to the base resin, 68-7 scaly silver powder
A method for producing a heat-resistant conductive adhesive comprising the step of adding 2 wt% and mixing and dispersing.