JPS604523A - Electrical insulating resin paste - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat dissipating thermosetting insulating resin paste comprising a thermally conductive filler and a liquid epoxy resin.

More specifically, the present invention relates to a solvent-free, non-conductive liquid mounting resin composition.

Due to recent significant developments in the electronics industry, transistors, With the advancement of LSI and VLSI, the integration of circuits in these semiconductor devices rapidly increased, and mass production became possible.This, combined with the decline in the price of semiconductor products, led to a production β of 7. Labor saving, efficiency, and raw material cost savings have become an important issue.

In the conventional method, a semiconductor component is produced by mounting a semiconductor element or chip on a substrate conductor or a lead frame using gold foil, and then sealing it with a metal seal. As an improvement method, a sealing process using thermosetting resin was developed, and along with this, a mounting process containing silver powder (1) was implemented, which improved productivity and reduced costs. In this case, many of MO8 and Engineering C are relatively cheap @ 5 without using a special material to pull out the sub electrode from the pumping gear above the red target. A non-conductive material is sufficient, and as a result, the total cost can be significantly reduced.

The heat dissipating thermosetting insulating resin paste of the present invention is suitable for such purposes.

Recently, the automation and speeding up of tyrannomount equipment has progressed, and the requirements for the properties necessary for the one-component mounting resin used therein are becoming more stringent.

The following characteristics of the mounting resin are the following:

■ Mount strength: -65 to 150 when heated at 350℃
Adhesion strength after temperature shock cycle, hot water treatment, etc.

■ Heat dissipation; ■ Workability; fixed-quantity injection with dispenser, screen printing, and stamping.

■ Curing properties: open method, hot plate method, etc.

■ Void: Low.

■ Reliability: No defects in moisture resistance current test. That is, there should be no migration of silver, no variation in device characteristics due to gases generated by cured adhesive, no corrosion of aluminum wiring due to ionic impurities such as 710 Dan, and alkali metals.

■ Wire bonding properties: There should be no deterioration in bonding properties due to gases generated by the cured product, and no contamination due to bleeding.

■ 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 1.0001) PI or more. For this reason, the amount of hot water-extracted chlorine ions in the Brera Schachtska 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.

As a result of various studies on these points, the present inventors found that the thermally conductive filler to be used in a heat dissipating thermosetting insulating resin consisting of a thermally conductive filler, an epoxy resin, a curing agent, and a curing accelerator. , the thermal conductivity is 10 k/Wm K (
0°C), preferably 20/Wm K or higher.The epoxy resin is a mixture of a liquid alicyclic epoxy resin and a glycysil type polyfunctional epoxy resin, and contains no hydrolyzable halogen. The curing agent is finely powdered dicyandiamide, and the curing accelerator is a tertiary amine salt. 20 hours) to less than zoo ppm, further improving reliability. 1
It is possible to cure in 0 seconds or a shorter cycle, and the bonding process and mounting process can be performed simultaneously on a hot plate.■ It has particularly excellent tack-free properties, and can be used not only with the icer method but also with the icer method. The present inventors have discovered that the present invention has many advantages, such as being able to be continuously applied over a long period of time to methods such as , screen printing, and stamping.

The thermally conductive filler used in the present invention has a thermal conductivity of 1
0/Wm K (Q°C) or more, preferably 20 k/
It is more than WmK. Furthermore, it is necessary that it 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 halogens. Therefore, the surface of the filler may be appropriately treated with a surface treatment agent such as a silicone-based, fluororesin-based, or organic titanate-based agent.

Further, washing may be performed as appropriate with water, a solvent, or the like.

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, ■ Fully fine powders of copper, aluminum, magnesium, iron, tin, etc., ■ Berylum, magnesium, aluminum, titanium,
Crystalline oxides such as silicon, carborundum, boron carbide, boron nitride monoaluminum nitride,
Non-oxide type ceramic fine powder such as titanium nitride.

Among these, metal oxides and non-oxide type ceramics are particularly preferred because they are non-conductive.

The mixing ratio (volume) of the filler and resin (including the curing agent) used in the present invention is preferably as high as possible within a range that does not deteriorate performance. Usually 20/(fund) to 40/6
It is within the range of 0 (capacity ratio).

The alicyclic epoxy resin used in the present invention includes epoxycyclohexylmethyl-epoxycyclohexanecarboxylic acid ester, bis(epoxycyclohexylmethyl)
These include diesters of aliphatic dibasic acids such as succinic acid, adipic acid, and sepatic acid, vinylcyclohexene dioxide, dicyclopetandadiene dioxide, and lower alkyl derivatives thereof.

Since the epoxy group of the alicyclic epoxy resin is not a terminal epoxy group but an internal epoxy group, acid anhydrides are particularly effective as curing agents, but amines are not very effective. However, when it is used in combination with a glycitoul type polyfunctional epoxy resin as in the present invention, it is thought that this serves as the starting point for ring-opening polymerization9, and that the curing reaction proceeds smoothly in the form of copolymerization of the two. That is, although internal epoxy groups alone do not cure sufficiently with dicyandiamide, when they coexist with terminal epoxy groups, copolymerization between the two occurs, resulting in good curing.

For the purposes of the present invention, epoxycyclohexylmethyl-epoxycyclohexane carboxylic acid ester types are particularly preferred as they have a high boiling point and low viscosity.

One of the major features of alicyclic epoxy resin is that it essentially contains a hydrolyzable halodane group as an impurity.

The content of hydrolyzable halodane groups in the epoxy resin of Glycitool tights used in the present invention is 1. o
It is desirable that the amount is less than oo ppm (preferably 600 ppm), and it may be adjusted to this level by appropriately blending two or more resins.

Since ordinary epoxy resins often have an excessive amount of hydrolyzable no-logon groups and are not suitable for the purpose of the present invention, it is desirable to perform appropriate purification before use.

Furthermore, the epoxy resin used in the present invention must contain 2.5 or more epoxy groups per molecule. The number of epoxy groups per molecule is 2 like the normal Ebibis type.
．． A value of 0 is not desirable because sufficient heat resistance and rapid curing properties cannot be obtained. However, it is also possible to use a combination of trifunctional or higher functionality and bifunctional functionality to give an average functionality of 2.5 or more.

Any epoxy resin that satisfies the above conditions can be used as the epoxy resin used in the present invention, but the following types are particularly preferred.

Phloroglucyshield triglycidyl ether, lycidyl ether, tetraglycyl ether of tetrahydroxybisphenol F, tetraglycyl ether of tetrahydroxype/zopheno/, epoxidized nogorac, epoxidized polyvinylphenol, triglycyl isocyanurate, Tri- or more polyfunctional epoxies such as triglycyl cyanurate, triglycyl S-) lyazine, triglycyl aminophenol, tetraglycyl diaminodiphenylmethane, tetraglycyl metaphenylene diamine, tetraglycyl pyromellitic acid, etc. Resin and bifunctional epoxy resin blended therein, such as diglycidyl resorcin, diglycidyl bisphenol A1 diglycidyl bisphenol F1 diglycidyl bisphenol S1 diglycidyl ether of zohydroxypenzophenone, diglycidyl oxy Benzoic acid, diglycidyl phthalic acid (Ol, ml+), diglycidylhydantoin, diglycidylaniline, diglycidyltoluidine, etc., or a condensation type resin thereof.

In addition, special types of allylated polyphenols, such as mono- to trinuclear-based epoxidized products with peracid, which have a glycysyl ether group and a nuclear-substituted dalicidyl group also meet the above conditions. If so, you can use it in the same way.

In the present invention, the ratio of the alicyclic epoxy group that essentially does not contain a hydrolyzable halogen group as an impurity and the polyfunctional epoxy group of Glycysil Tights containing the alicyclic epoxy group is 90/1.
By blending the resin at a ratio of 0 to 40/60, the amount of hydrolyzable halogen groups in the entire resin can be reduced to 600'9'9m%.
Preferably it is completely below 400 ppm.

The curing agent used in the present invention must be latent, and dicyandiamide is most suitable.

However, since dicyandiamide is difficult to dissolve in the resin, if it is coarse, it may settle, resulting in uneven dispersion and uneven hardening. Preferably.

It is not preferable to use dicyanamide as a solution since a volatile solvent will be included in the composition.

The particle size of the dicyandiamide to be used is preferably 350 mesh pass; otherwise, a uniform cured product may not be obtained and performance may vary, which is not preferable. The above-mentioned pulverization is essential for improving the reliability of mounting resin.

The curing accelerator used in the present invention is a tertiary amine salt,
Salts of at least 1 ai tertiary amines selected from the group of dimethylbenzylamine, tris(dimethylaminomethyl)phenol, alicyclic superbases, imidazoles, and polyhydric phenols and polybasic acids. It is desirable that there be.

Alicyclic superbases include trimethylenediamine, 1,8-diaza-bicyclo-(5,4,0)undecene-7, dodecahydro-1,4,7,91)tetraazaphenalene, and the like.

Imidazoles are those in which a substituent such as methyl, ethyl, propyl, a long-chain alkyl group up to 017, or a phenyl group is introduced at the 2- and/or 4-position.

Those that form salts with these tertiary amines include:
Polybasic acids such as phthalic acid #(o+m+p), tetrahydrophthalic acid, endomethine/tetrahydrophthalic acid, dimer acid, hexahydrophthalic acid, trimellitic acid, adipic acid, succinic acid, maleic acid, itaconic acid or resorcinol, pyrogallol, hydroquinone , bisphenol A1 bisphenol F1 bisphenol S% low e
Polyhydric phenols such as novolak.

The amount of these tertiary amine salts is preferably in the range of 0.1 to 10 parts per 100 parts (by weight, the same applies hereinafter) of the epoxy resin. If it is less than this, the promoting effect is insufficient and the
If the amount is more than this, the curing will not be promoted much, but the storage stability may be deteriorated, so it is not desirable.

Note that these tertiary amine salts tend to absorb moisture and carbon dioxide gas before use, which tends to deteriorate their performance.
(weight) or less, it is preferable that the amount of CO2 gas absorbed is 5% or less. Once it has absorbed water and CO2 gas, it is difficult to make it into a sufficient amount, so it is generally preferable to purify it before use.

In order to stabilize the curability of the mount resin, it is preferable to use a resin 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. In any case, it is preferable that aromatic low-boiling point solvents are not included as much as possible.

In addition, it is preferable that the material is not silicone-based so as not to cause contact failure.

In the alicyclic epoxy resin, curing agent, curing accelerator, etc. used in the present invention, it is desirable that the content of ionic impurities such as CZ ions and Ha ions is 10 pI)m or less. However, these raw materials essentially do not contain hydrolyzable halogen groups like glycysil type epoxy resins, nor do they contain these ionic impurities, and cannot be processed by distillation, recrystallization, etc. The conventional fAfiA is sufficiently suitable for the purpose of the present invention.

The test method for ionic impurities is as follows.

For chlorine ions, liquid sample 15F was mixed with 201Fll of pure water and 2
After shaking for an hour, centrifuge the aqueous layer and use it as a test solution. Next, test solution 1
5 CCf Collected in a whole pipette, 4 ml of 6% iron alum aqueous solution, 0.3% thiocyanic acid/water M ethanol solution 2- were added, and diluted with pure water to a concentration of 25-. The absorbance of the obtained test solution at a wavelength of 460 wn was measured using a spectroscopic needle, and the concentration of chlorine ions contained as impurities was determined using a calibration curve prepared in advance in comparison with a blank test.

For epoxy resins, mounting resin compositions, curing agents, etc., in the case of viscous liquids or solids, sample 15 F was uniformly dissolved in 30 m of toluene, and 100 m of pure water was added.
Centrifuge the water-extracted layer after time shaking to prepare a test solution, and proceed in the same manner.

Sodium ions were measured using a flameless atomic absorption spectrometer with the above sample solution at a wavelength of 330.2 nm, and in comparison with a blank test, sodium ions contained as impurities were determined using a calibration curve prepared in advance. Ru.

The fixed lid method for hydrolyzable chlorine in epoxy resin is
Dissolve r in 30ml of toluene, and then add g, I N No
Heat and reflux the n-ethanol solution for 50 minutes, then titrate the amount of alkali consumed with Q, l N H (3). Calculate the chlorine cap and use it as the amount of hydrolyzable chlorine.
The conventional measurement method was to heat and reflux a solution of N KOH-methanol for 15 minutes, but this method is not preferable for the purpose of the present invention because it gives a too small value for the amount of hydrolyzable chlorine.

The method for measuring hydrothermally decomposable chlorine ions in the cured product using the Brella Schachtska test is as follows.

The mounting resin is cured for one blade of 200'C, and then the cured product is crushed. The obtained powder sample 21 is thoroughly immersed in ethanol 3- in a decomposition crucible. Next, after adding 40° of pure water, the container is completely sealed and treated at 125° C. for an extended period of time. After processing, it is loaded, centrifuged, and the supernatant is used 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, etc. are weighed out and kneaded to form a uniform solution.

In this case, the crosstalk includes a normal stirring tank, catcher, three rolls,
An appropriate combination of ink mills and the like may be used.

Next, the filler for a given lid is weighed out and kneaded with the resin solution to form a completely uniform paste. In this case as well, a stirring tank,
Use a combination of Shinzukeki, Sanppon Roll, etc. as appropriate. Next, the paste-like resin composition is weighed and distributed into predetermined containers, and subjected to IGI in a Makabe chamber to obtain a product.

In this case, if the mounting resin layer is thick, it will not be possible to remove bubbles sufficiently, so it is preferable to make the layer as thin as possible.

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, including hydrothermally decomposable impurities, in the mounting resin composition must be extremely small.

(2) Good deep-temperature curing properties: Curing can be performed in a sufficiently short cycle on a hot plate, and the chip mounting process can be significantly shortened.

(3) Tack 7 should have particularly good consistency. It should be possible to operate for long periods of time in stamping, screen printing, etc., and it should have excellent workability.

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

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

Examples will be described below.

Example 1 As an alicyclic epoxy resin, 3,4-epoxycyclohexylmethyl-3,4 epoxycyclohexanecarboxylic acid ester C viscosity e: 4 voids/25°C, epoxy equivalent +
140, number average molecular weight; 285, number of epoxy groups 7 molecules + 2.0, hydrolyzable chloro; none) 80 parts, as a glycysil type polyfunctional epoxy resin, epoxidized phenol? Lac (number average molecular weight; 650, epoxy equivalent +175, number of epoxy groups: 7 molecules i3.7, hydrolyzable chlorine group; soo ppm) 20 parts, 5.0 parts of dicyandiamide pre-pulverized with 350 mesh pass as a hardening agent , a resol-resibase of triethylenediamine as a curing accelerator. , 5 parts, fluororesin antifoaming agent 0
901 parts were stirred to form a uniform dispersion. Furthermore, 100 parts of crystalline silica powder is added and kneaded using a crusher, and finally passed through three rolls to obtain a uniform paste-like mount resin composition.

The resulting paste-like mounting resin composition had a liquid thickness of 2
Spread it in a vat to below 0m and empty it at room temperature.
Defoaming is performed under high vacuum of 5wnHf or less. The defoamed resin composition is automatically supplied quantitatively onto the lead frame by one-shot printing or stamping to mount the chip.

Curing of the resin is achieved by cycles of heating and heating at 350° C. on a hot plate.

The performance of various mounting resins is shown in Table 1.

In addition, in the above epoxy resin, if only an alicyclic epoxy resin is used without a Glycyseal type multifunctional epoxy resin, it may be difficult to cure depending on the above curing agent and curing accelerator. Therefore, it is undesirable.

Example 2 The same alicyclic epoxy resin as in Example 1 was used, and the glycysyl type polyfunctional epoxy was triglycisol ether of phloroglucin (number average molecular weight: 370, epoxy equivalent: 130, number of 7 molecules of epoxy group). i2.8, hydrolyzable chloro group; 900 ppm) is used.

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

Alumina powder is used as the filler.

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

Comparative Example Both the alicyclic epoxy resin and the glycysil type polyfunctional epoxy resin are the same as in Example 1.

Methylhexahydrophthalic anhydride is used as a curing agent, and pentamethylene diethylene triamine is used as a curing accelerator. The filler is alumina.

The formulation, paste properties, curing conditions, and performance of the cured product were determined by the energization shown in Table 1.

In this case, it is difficult to perform curing at high temperature in a short time, which is not desirable. That is, an extremely long curing cycle of 10-odd hours at 81 J to 120° C. is required.

Procedural amendment (spontaneous) August 3, 1980 Commissioner of the Japan Patent Office 1, Indication of the case 1988 Patent Application No. 111813 2, Name of the invention Insulating resin paste 3, Person making the amendment Relationship to the case Patent application Address: 1-2-2-4 Uchisaiwai-cho, Chiyoda-ku, Tokyo, Detailed description of the invention in the specification to be amended.

5. Contents of correction (1) Page 16, line 13 “10g” 30ml of luene, additional 1:o,
IN KO February is corrected to ``0.5g to 30ml of dioxane, and further corrected to INKO old.

Procedural amendment (spontaneous) January 5, 1980 To the Commissioner of the Japan Patent Office i, i; Indication of the matter Patent Application No. 111813 of 1982 2 Name of the invention Insulating resin paste 3 Relationship with the case of the person making the amendment Patent applicant address: 1-2-2-4 Uchisaiwai-cho, Chiyoda-ku, Tokyo. Detailed description of the invention in the specification subject to amendment.

5. Contents of correction (1) Page 16, line 15, "The amount of alkali consumed was changed to 0.1 NHC1" to [The amount of chlorine produced was changed to 0.1 NHC1. OIAgNO,” is corrected.

(2) Page 16, lines 16-17

Claims (1)

[Claims] A heat-dissipating thermosetting insulating resin paste comprising a thermally conductive filler, an epoxy resin, a curing agent, and a curing accelerator, the paste comprising:
The thermally conductive filler has a thermal conductivity of IQ k/wm K (
The liquid epoxy resin is a mixture of a liquid alicyclic epoxy resin and a polyfunctional epoxy resin of Glycyseal Tights, and has a hydrolyzable halogen group of 30 ppm (weight) or less. An insulating resin paste characterized in that the curing agent is dicyancyamide and the curing accelerator is a tertiary amine salt.