JPS604521A - Electrical insulating resin paste - Google Patents

Abstract

PURPOSE:The titled paste useful for nonelectrically-conductive one-pack type mount, having high purity, high-temperature curing properties, and especially improved tack-free properties, consisting of a specific thermally conductive filler, an epoxy resin, a curing agent, a curing promotor, and a reactive diluent. CONSTITUTION:The desired paste consisting of (A) a thermally-conductive filler having >=10K/Wm<-1>K<-1>(0 deg.C) thermal conductivity, (B) a liquid epoxy resin having <=600ppm(weight) hydrolyzable halogen group content, and >=2.5 epoxy group per molecule, (C) a curing agent consisting of dicyandiamide, (D) a curing promotor consisting of a tertiary amine, and (E) a reactive diluent having >=1 epoxy group per molecule, having >=250 deg.C boiling point, <=10 poise/25 deg.C viscosity, and <=1,000ppm hydrolyzable halogen group content.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-dissipating thermosetting resin paste consisting of a thermally conductive filler and a liquid epoxy resin. Things; = related to things.

Due to recent remarkable developments in the electronics industry, transistors, ICs, LSIs, and ultra-LSIs have evolved, and the degree of integration of circuits in these semiconductor devices (=increases rapidly(''')--mass production has become possible, and the use of these devices has increased rapidly. Together with the decline in prices of semiconductor products, labor-saving and efficiency during production (= reduction in raw material costs) have become important issues.

The conventional method involves mounting a semiconductor element or chip on a substrate conductor or lead frame using two-gold foil, and then hermetically sealing it.
It was considered more of a semiconductor component. As an improvement method, a sealing process using thermosetting resin was developed, and a mounting process using electrocardiographic resin containing silver powder was also implemented (-, which improved productivity and cost. In this case, in most MO8 ICs, the sub-electrode is pulled out from the bodding butt on the pellet (secondarily, the metallization on the back side of the pellet can be omitted. As the resin, it is not necessary to use an expensive conductive resin, but a relatively inexpensive non-conductive resin is sufficient, and the total cost can be significantly reduced.This invention The heat-dissipating thermosetting resin paste is suitable for this purpose.

Recently, the automation and speeding up of TEP mounting equipment has progressed, and the requirements for the characteristics necessary for a one-component resin for mounting are becoming more stringent.

The properties necessary for a mounting resin are as follows.

■Mount strength: -65 to 150℃ when heated at 350℃
Good adhesion after heat shock cycles, hot water treatment, etc.

■ Heat dissipation properties ■ Workability; Dispenser (good quantitative injection properties, screen printing properties, stamping properties, etc.).

■Curing properties: Oven method, hot plate method, etc.
= good curing properties.

■Board: Low.

■Reliability: Moisture resistance current test; No secondary defects.

In other words, silver migration Gas generated from cured adhesive (Due to variations in device characteristics, halogen ionic non-containers such as carbon, alkali metals, Blunt objects (corrosion of aluminum wiring, etc.) That there is no.

■Wire bonding property; gas generated from cured product (
There should be no deterioration of bonding properties due to secondary defects, bleed, or contamination due to secondary defects.

■Pellet crack: A good buffer against stress caused by the difference in thermal expansion with the lead frame (especially in the case of copper alloy).

The biggest problem with conventional mounting resins of this type is as follows.

(2) The epoxy resin used contains a large amount of hydrolyzable halogen groups as impurities of i, ooo ppm or more. Therefore, the amount of hot water extracted chlorine ions in the pressure courier test (20 hours) is as large as several hundred ppm or more, which is extremely unsatisfactory in terms of reliability.

■ In terms of workability and curing properties, efforts to save labor and increase speed are inadequate.

The inventors have made these points (as a result of various studies)
A heat-dissipating thermosetting resin paste consisting of a thermally conductive filler, an epoxy resin, a curing agent, a curing accelerator, and a solvent (2) The thermally conductive filler used has a thermal conductivity of 10 kl.
--1x-1<oC), preferably at 20/Wm =
K-' or higher, it is liquid as an epoxy resin, and the content of hydrolyzable halogen groups is 600 ppm (
weight, the same applies hereinafter) or less, and the epoxy group is 2 per molecule.
．． The curing agent is ginandiamide, the curing accelerator is a tertiary amine salt, the reactive diluent is at least one epoxy group per molecule, By having a boiling point of 250°C or higher, a viscosity of 10 poise/25°C or lower, and a content of dihydrolyzable halogen groups of 1,000 ppm,
The halogen ion concentration in hot water extraction has been significantly reduced to less than 9 (Pressure 4 - Kutsker test 20 hours), which further improves reliability. Curing can be done in 5 minutes at 300°C, 1 minute at 350°C, and 10 seconds at 450°C, or shorter cycles, making it possible to perform the bonding process and mounting process on a hot plate at the same time. ■Tank-free. However, the present invention was achieved by discovering that it has many advantages such as being able to be applied continuously for a long time not only to the dispenser method but also to the screen printing method and the stamping method.

The thermally conductive filler used in the present invention (2) has a thermal conductivity of 1' to IQk/W'm-' (0°C) or more, preferably 1' to 20/Wm-' or more. In addition, it is necessary that the filler has good compatibility with the epoxy resin, does not absorb a large amount of resin, and does not contain ionic impurities such as alkali metal ions and norogen ions.For this reason, the filler surface must be treated with an appropriate surface treatment agent, such as silicone-based , fluororesin,
It may be treated with an organic titanate or the like. Also water 1
．． Washing with a solvent or the like may be carried out as appropriate.

Any filler that satisfies the above conditions can be used in the present invention, but fillers that are as low cost as possible are preferred. - Examples are as follows.

■ Crystalline carbons such as graphite; ■ Fine metal powders such as copper, aluminum, magnesium, iron, and tin; ■ Beryllium, magnesium, and aluminum.

Crystalline oxides such as titanium and silicon, non-oxide type ceramic fine powders such as carborundum, boron carbide, nitride cavities, aluminum nitride, and titanium nitride; Oxide and non-oxide type ceramics are preferred as they are non-conductive.

The advantage of the present invention is that the mixing ratio (volume) of the filler and the resin containing the curing agent to be used is preferably as high as possible within a range that does not deteriorate the performance, since heat dissipation is excellent. Usually 2
It is within the range of 0/80 to 40/60 (capacity ratio).

The epoxy resin used in the present invention must be liquid, have a hydrolyzable halogen group content of 600 ppm or less, preferably aoo ppm or less, and contain 2.5 or more epoxy groups per molecule. be.

It goes without saying that the amount of ionic impurities such as halogen ions and alkali metal ions is 1Q ppm or less.

There are various methods for reducing the amount of hydrolyzable halogen groups in the epoxy resin to 600 ppm or less, preferably 300 ppm or less, and one example is as follows.

■ Epoxy resin in which a polyactive hydrogen compound (polyhydric phenols, polybasic acids, etc.) and epihalohydrin are reacted using quaternary ammonium hydroxide as a catalyst, and the resulting halohydrin group is ring-closed with an alcoholic alkali. manufacturing method.

■ A method for purifying epoxy resins in which residual halohydrin groups, mainly hydrolyzable halogen groups, are ring-closed by heating with an equivalent amount of alcoholic alkali in an anhydrous state.

■ Purification method 1 in which remaining halohydrin groups are reacted with an equivalent amount of fatty acid silver salt in an anhydrous state to form Ag A method for producing epoxy resin by epoxidizing it with peracid such as chlorbenzoic acid.

For the purpose of the present invention (2), no matter which method is used to obtain a resin with a small amount of hydrolyzable halogen groups, it is possible to have two phases, so the method for reducing the amount (2) is not restricted.

The epoxy resin used in the present invention may be adjusted by appropriately blending two or more resins to form this epoxy resin.

Ordinary epoxy resins usually contain 1,000 ppm or more. Therefore, for the purpose of the present invention, it is not desirable to use ordinary commercially available epoxy resins as they are.

Furthermore, it is necessary that the epoxy resin used in the present invention contains 2.5 or more epoxy groups per molecule.

Like the normal Ebibis type (2.0 epoxy groups per molecule is not desirable because sufficient heat resistance and rapid hardening properties cannot be obtained.However, trifunctional or higher epoxy groups are not desirable. It may also be used by blending with a difunctional one to have an average functionality of 2.5 or more.

In the present invention, any epoxy resin can be used as long as it satisfies the above conditions, but primary type epoxy resins are particularly preferred.

Phlorogrunshield triglycidyl ether, triclycidyl ether of trihydroxybiphenyl, tetraglycidyl ether of tetrahydroxybiphenyl, tetraglycidyl ether of tetrahydroquine bisphenol F, tetraglycidyl ether of tetrahydroxybenzophenone Ether, epoxidized novolak, epoxidized polyvinylphenol, triglycyl rayson anurate, triglycyl cyanurate, triglycyl S-) lyazine, triglycyl aminophenol, tetraglycyl diaminodiphenylmethane, tetraglycyl metaphenylene diamine, tetra Tri- or more polyfunctional epoxy resins such as grindyl pyromellitic acid and bifunctional epoxides blended therewith, such as diglycidyl resorcin, diglycidyl bisphenol A, diglycidyl bisphenol F1 diglycidyl Diglycidyl ether of bisphenol S1 dihydroxybenzophenone, diglycidyloxybenzoic acid, diglycidyl phthalic acid (0',, m, p)% diglycidylhydantoin, diglycidylaniline, diglycidyl toluidine, etc., or These are condensation type resins.

Also, as a special type, allylated polyphenol (1
The same applies to peracids containing glycysyl ether groups and nuclear-substituted glycysyl groups, such as di-based epoxides, if the above conditions are met. It can be used.

In the present invention (=The curing agent used must be latent, and dianediamide is most suitable.

However, since diandiamide is difficult to dissolve in the resin (2), if it is coarse, it may precipitate, resulting in non-uniform dispersion and non-uniform curing. It is necessary that the diamide is pulverized.Using dianediamide as a solution is not preferable because volatile solvents will be included in the composition.

The particle size of the diandiamide used is preferably 350 mesh pass. If the powder is not such a fine powder, a uniform cured product cannot be obtained and there is a risk of variations in performance, which is not preferable. In order to improve the reliability of the mounting resin (=, the above-mentioned pulverization is essential.

The present invention (=the curing accelerator used is a salt of a tertiary amine, such as dimethylbenzylamine, tris(dimethylaminomethyl)phenol, or alicyclic superbase).

Desirably, the salt is a salt of at least one tertiary amine selected from the group of imidazoles, and polyhydric phenols and polybasic acids.

Alicyclic superbases include trimethylene diamine, 1,8-diaza-bicyclo-(5,4,0) undecene-7, dodecahydro-1,4,7,9b tetraazaphenalene, and the like.

Imidazoles are those in which a substituent such as a long-chain methyl alkyl group or a phenyl group is introduced at the 2- and/or 4-position.

Those that form salts with these tertiary amines include:
Polybasic acids or resorcinols such as phthalic acid (o, m.p.), tetrahydrophthalic acid, endomethylenetetrahydrophthalic acid, dimer acid, hexahydrophthalic acid, trimellitic acid, adipic acid, succinic acid, maleic acid, itaconic acid , pyrogallol, hydroquinone, bisphenol A, bisphenol F1, pinuphenol S, and low-molecular-weight novolak.

The salts of these tertiary amines are desirably in the range of 0.1 to 10 parts per 100 parts (by weight, the same below) of the epoxy resin.If the amount is less than this, the promoting effect will be insufficient; Even if you increase the amount, curing will not be promoted much (=
Both are undesirable because they may deteriorate storage stability.

In addition, these tertiary amines tend to absorb moisture and carbon dioxide before use, and their performance deteriorates more easily than in the present invention. It is preferable that the amount of CO2 gas absorbed is 10% or less (by weight) and the amount of CO2 gas absorbed is 5% or less.Once water and CO2 gas have been absorbed, it is difficult to sufficiently purify it, so it is generally recommended to use it after purification. do not have.

In order to stabilize the curability of the mount resin (- is preferably within the above range).

In the present invention, a defoaming agent, a surface treatment agent, etc. may be used as appropriate.

As the defoaming agent and surface treatment agent, any of silicone-based, fluororesin-based, and other organic titanate-based agents may be used. It is preferable not to contain aromatic low-boiling point solvents as much as possible.

Also, it is preferable that it is not silicone-based so as not to cause contact failure.

The present invention (the two-phase reactive diluent has at least one terminal epoxy group per molecule, has a boiling point of 250°C or higher, preferably 300°C or higher, and has a low viscosity of 10 poise/25°C or lower). and the content of hydrolyzable halogen groups is 1,000 pI)m or less, preferably 60
0 ppm or less. If the boiling point is lower than this, when screen printing or stamping is performed continuously for a long time,
It is undesirable because it gradually volatilizes and the viscosity increases, which causes workability to deteriorate over time. Also, if the viscosity is higher than this, it is undesirable because a sufficient dilution effect cannot be achieved.

Generally speaking, high-boiling point epoxy compounds used as diluents (for example, those containing a large number of hydrolyzable halogen groups, such as Grindyl ether of polyether polyol) are unsuitable for the purposes of the present invention. Monoglycyl ethers of Cl0-40 long-chain fatty acids are suitable because they satisfy all of the above conditions. Similarly, polyglycyl ethers of dimer acids are also effective.

Note that monofunctional diluents reduce the crosslink density of the cured product,
Since there is a risk of deteriorating performance under heat, it is necessary to use as little amount as possible.

The method for reducing the hydrolyzable halogen group in the reactive diluent is almost the same for epoxy resins (two methods can be used).

The curing agent, curing accelerator, reactive diluent, etc. used in the present invention must all contain as little C2 as possible, for example, 10 ppm or less, of ionic impurities such as Cl ions and Na ions. However, these raw materials essentially do not contain hydrolyzable halogen groups like epoxy resins, nor do they contain these ionic impurities, and cannot be processed through ordinary refining methods such as distillation and recrystallization. The objective C of the present invention is more fully achieved.

The test method for ionic impurities is as follows.

To obtain chlorine ions, shake 15 g of a liquid sample with 20 fnl of pure water for 2 hours, then centrifuge the aqueous layer to obtain a test solution. Next, test solution 15c
Collect c with a whole pipette, add 4 ml of 6% iron alum aqueous solution, and 2 ml of 0.3% hexaosyanic acid/mercury ethanol solution.
Add 1 ml and dilute with pure water until the volume becomes 25 ml. The absorbance of the obtained test solution was measured with a spectrophotometer at a wavelength of 460 nm (:) and compared with a blank test. Ru.

In the case of epoxy resins, mounting resin compositions, curing agents, etc., which are in the form of medium-powder liquids or solids,
Add 0ml, shake for 2 hours, centrifuge the condensate layer to prepare a test solution, and perform C2 in the same manner.

Sodium ions were detected using a frameless atomic absorption spectrometer, and compared with a blank test based on the absorbance at a wavelength of 330.2 nm. I put it on.

The method for quantifying hydrolyzable chlorine in epoxy resin is
) Le x y 30 ml + 2 combs, further (20.I
NKOH-ethanol solution was heated to reflux for 30 minutes, and then the amount of alkali consumed was reduced to 0. I N HC
Titrate from 6+2. Calculate the amount of chlorine equivalent to the amount of alkaline consumed and use it as the amount of hydrolyzable chlorine. Note that 0
．． The conventional measurement method was to heat and reflux an I N KOH-methanol solution for 15 minutes, but this gives an underestimate of the amount of hydrolyzable chlorine, so for the purposes of the present invention (= is not preferred).

The method for measuring hydrothermally decomposable chlorine ions from the cured product using the pressure Kutzker test is as follows.

The mounting resin is cured at 200° C. for 30 minutes, and then the cured product is crushed. 2 g of the obtained powder sample is thoroughly immersed in a decomposition crucible by adding 3 tnl of ethanol. Next (= After adding 40ml of pure water, completely seal it and keep it at 125℃.
, treated for 20 hours. After treatment, if necessary, centrifuge and use the supernatant as the test solution.

Determine the chloride ion concentration and sodium ion concentration in the test solution according to the above method.

The manufacturing process of the insulating resin paste of the present invention is as follows.

First, predetermined amounts of epoxy resin, curing agent, curing accelerator, reactive diluent, etc. are weighed out and kneaded to form a uniform solution. In this case, a suitable combination of a mixing tank, a crusher, a triple roll, an ink mill, etc., may be used.

Next, a predetermined amount of filler is weighed out and kneaded with the resin solution to form a complete (=uniform paste). In this case as well, an appropriate combination of a stirring tank, crusher, triple roll, etc. is used. Next, the paste-like resin composition is distributed into predetermined containers (two scales) and defoamed in a vacuum chamber to produce a product. (
Two M layers (preferably two).

The resin composition thus obtained needs to be stored and transported at temperatures of -15°C or lower. If the temperature is higher than this, the shelf life will be significantly reduced, which is not preferable.

The insulating resin paste of the present invention has the following features compared to conventional products.

(1) High purity: The amount of ionic impurities in the resin paste (including those that are hydrolytically decomposable) is extremely small.

(2) Good high-temperature curing properties: Can be cured in a short cycle on a hot blast, and the chip mounting process can be significantly shortened.

(3) Particularly good tack-free properties: Long-term operation for stamping, screen printing, etc. is possible, and workability is excellent.

(4) Other properties, such as mounting strength and heat dissipation, are no better than conventional products.

Therefore, the insulating resin base of the present invention has extremely high industrial value and meets the needs of the electronics industry, which has recently been rapidly becoming more sophisticated.

Examples will be explained below.

Example 1 Epoxidized phenol novolak (number average molecular weight: 550, epoxy equivalent: 170, number of epoxy groups: 7 molecules: 3.2, hydrolyzable chloro group t 5) was used as the epoxy resin.
00 ppm) 70 parts, Ct as reactive diluent
a) 30 parts of long-chain fatty acid grindyl ester (hydrolyzable chlorine group; 900 ppm), 40 parts of ginandiamide, which had been previously pulverized to 350 mesh as a curing agent, and 1.8 diaza-bicyclo (as a curing accelerator) 5,4,,)) Resorcinol salt of undecene-70.
3 parts and 0.01 part of a fluororesin antifoaming agent were stirred to form a uniform dispersion. Add 100 parts of di-crystalline powder and knead with a crusher, and finally pass through a few rolls to obtain a uniform paste-like mounting resin composition.

The resulting paste-like mounting resin composition had a liquid thickness of 2
Spread the mixture in a vat to a temperature below 0.5 mmHg and degas it in a vacuum chamber at room temperature under a high vacuum below 5 imHg.

The defoamed resin composition is then screen printed or stamped onto the lead frame (automatically dispensed) to mount the chip.

To harden the resin, leave it in a heating oven at 200°C for 120 minutes (obtained from Section 2).

Table 1 shows the performance of various mounting resins.

In addition, when the above-mentioned epoxy resin is used as it is commercially available without purification, the amount of hydrolyzable chlorine groups is 1,200
It is ppm. If this is used as is, the amount of chlorine ions after hot water extraction will be 350 ppm.

This value is undesirable for precision electronics devices from the viewpoint of reliability.

Example 2 The epoxy resin was an Epibis liquid epoxy resin (number average molecular weight: 400, epoxy equivalent: 190, number of epoxy groups/molecule: 2.O1 hydrolyzable chlorine group; 2
00 ppm) and triglynesyl ether of phloroglucin (number average molecular weight: 360, epoxy equivalent: 1
25, Number of epoxy groups: 7 molecules; 2.9, Hydrolyzability: 1
71L/group; 700 pI) m> and 1.0/
A ratio of 3.0 (= a mixture is used. Alumina is used as the filler. The reactive diluent, curing agent, curing accelerator, and antifoaming agent are the same as in Example 1. Composition, paste properties, The curing conditions and performance of the cured product are shown in Table 1.

Example 3 The epoxy resin was made by epoxidizing allylated bisphenol F with peracid (number average molecular weight: 400.tt' per epoxy, 125, number of epoxy groups/molecule; 3.
A mixture of O1 hydrolyzable chloro group (absent) and the epoxidized phenol novolac of Example 1 at a ratio of 1.0/1.0 is used.

The filler, curing agent, curing accelerator, and antifoaming agent are the same as in Example 1.

The formulation, paste properties, and performance of the cured product are shown in Table 1.

Comparative Example All other raw materials are the same as in Example 1 except that phenylglycyl ether is used as the reactive diluent.

The formulation, paste properties, curing conditions, and properties of the cured product are shown in Table 1.

Due to the volatility of phenylglycyl ether, the tack-free properties deteriorate, making it impossible and undesirable to operate screen printing and stamping continuously for a long time.

Table 1: Vessel xlOmr/5ec-cl Fire pressure puller (2o hours) Procedure amendment (
(Spontaneous) August 3, 1980 Commissioner of the Japan Patent Office 1 Indication of the case Patent Application No. 111811 of 1988 2 Name of the invention Insulating resin paste 3 Relationship with the case by the person making the amendment Address of the patent applicant Tokyo 1-2-2-4 Uchisaiwai-cho, Chiyoda-ku, Miyako. Detailed description of the invention in the specification to be amended.

5. Contents of the amendment (1) Page 18, line 1 [10g of toluene 3011 mt. IN
KOIIJ Procedural Amendment (Voluntary) January 5, 1980 Mr. Commissioner of the Japan Patent Office 1, Indication of the case 1982 Patent Application No. 1 ] 1811 2, Name of the invention Insulating resin paste 3, Person making the amendment Case Relationship of Patent Applicant Address: 2-2-4 Ko-chome, Uchisaiwai-cho, Chiyoda-ku, Tokyo, Detailed description of the invention in the specification to be amended.

5. Correction details (1) Page 18, line 3, “The amount of alkali consumed is determined by 0.1 NI-ICI” is changed to “The amount of chlorine produced is determined by 0.01 A,NO
, amend it to "by".

(2) Page 18, lines 4-5 “Calculate the amount of alkali consumed and the equivalent amount of chlorine,
" is corrected by 1 and this value is ".

Claims (1)

[Claims] An insulating resin paste consisting of a thermally conductive filler, an epoxy resin, a curing agent, a curing accelerator, and a reactive diluent, the thermally conductive filler having a thermal conductivity of 10 to 7'Wm-'K-
(0°C) or above, the epoxy resin is liquid, the content of hydrolyzable halogen groups is 600 ppm (weight) or less, and the epoxy resin has an average of 2.5 or more epoxy groups per molecule, The curing agent is ginandiamide, the curing accelerator is a tertiary amine salt, and the reactive diluent has at least one epoxy group per molecule and has a boiling point of 250.
℃ or higher and a viscosity of 10 poise/25℃ or lower,
Further (= content of hydrolyzable herogen group is 1ooo pp
A solvent-free corrugated insulating resin paste characterized by having a weight of less than m (weight).