JP2983613B2 - Epoxy resin composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an epoxy resin composition for semiconductor encapsulation having excellent solder heat resistance, thermal shock resistance and moldability.

(Prior art) Epoxy resin is a resin with excellent heat resistance, electrical properties, mechanical strength and adhesiveness, and is widely used in paints, adhesives, resin for sealing electronic parts, resin for laminated boards and other various fields. Resin.

For example, epoxy resin compositions are generally used for resin sealing of semiconductor elements such as ICs, LSIs, transistors, diodes, and the like, and for resin sealing of electronic circuits and the like, in view of both characteristics and cost.

However, in recent years, due to the increase in IC size, miniaturization and thinning of package size, package cracking due to temperature cycling and package cracking due to solder thermal shock during surface mounting are more likely to occur. Is strongly required.

In order to improve these, studies are being made on lowering the elastic modulus, lowering the coefficient of thermal expansion, increasing the impact strength, and reducing the water absorption.

It is said that a method using a silicone-modified epoxy resin compound (JP-A-61-73725 and JP-A-62-174222) is effective for lowering the elastic modulus.
Simply lowering the elasticity lowers the strength, so that the solder heat resistance is lowered, and a good resin composition for semiconductor encapsulation cannot be obtained.

For lowering the coefficient of thermal expansion, increasing the amount of silica filler in the resin composition is said to be effective.However, an increase in the viscosity of the resin composition due to the increase in the amount of filler causes a problem, and a significant decrease in moldability is caused. I needed to clear it.

It is said that the use of a biphenyl type epoxy resin or a trifunctional epoxy resin (Japanese Patent Application Laid-Open No. 61-168620) is effective in increasing the impact strength. Is seen to decrease.

It is said that the use of a silicone-modified resin and an increase in the amount of a filler are effective in reducing the water absorption, but all have the above-mentioned drawbacks and have not been put to practical use.

(Problems to be Solved by the Invention) The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a semiconductor encapsulation having good solder heat resistance, heat shock resistance, and moldability. An object of the present invention is to provide an epoxy resin composition.

(Means for Solving the Problems) The present inventors have made intensive studies to obtain a well-balanced and excellent epoxy resin composition for semiconductor encapsulation that could not be overcome by the conventional technique, and as a result, molded the epoxy resin. An organopolysiloxane having a specific structure of at least one of the following formulas (I) and (II) having an effect of imparting remarkable toughness and low elasticity without impairing workability, and a phenol resin. React A resin composition comprising a curing agent and an inorganic filler obtained by blending a random copolymerized silicone-modified phenolic resin in an amount of 50 to 100% by weight with respect to the total phenolic resin has a moldability even in a thin and large chip package.
The inventors have found that both the solder heat resistance and the thermal shock resistance are significantly improved, and have completed the present invention.

(Operation) The epoxy resin used in the present invention has two or more epoxy groups in one molecule (however, a naphthalene-type epoxy resin represented by the following formula (a), Are excluded. ) May be used, and examples thereof include bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, alicyclic epoxy resin and modified resins thereof. Epoxy resin is one or two
A mixture of more than one species can be used.

Among these epoxy resins, the epoxy equivalent is 150 to 2
50, those having a softening point of 60 to 130 ° C. and containing as little ionic impurities as possible such as Na ⁺ and Cl ⁻ are preferable.

The random copolymer silicone-modified phenolic resin curing agent used in the present invention is a very important component having an effect of improving both the solder heat resistance and the thermal shock resistance.

Examples of the phenolic resin used as a raw material of these random copolymerized silicone-modified phenolic resin curing agents include phenol novolak, cresol novolak and modified resins thereof, and these can be used alone or in combination of two or more. .

The phenolic resin used has a hydroxyl equivalent of 80 to 150,
Those having a softening point of 60 to 120 ° C. and containing as little ionic impurities as possible such as Na ⁺ and Cl ⁻ are preferable.

The organopolysiloxane used as the other raw material has a structure represented by the formulas (I) and (II). It has the effect of improving solder heat resistance and thermal shock resistance without impairing moldability, and has a siloxane polymerization degree (k ++ m + 2) having a specific ratio of epoxy group-containing organic groups capable of reacting with phenolic hydroxyl groups at a specific ratio of 10%. In the range of from 200 to 200, the structure of the organopolysiloxane may be linear or branched.

Further, it is necessary to use a phenyl group or a phenylethyl group modified portion having a molar fraction (/ (k ++ m + 2)) of 0.1 or less and a siloxane polymerization degree / functional group number ((k ++ m + 2) / m) of 5 or more and 50 or less. .

If the siloxane polymerization degree (k ++ m + 2) is less than 10, the molecular weight of the silicone reaction portion becomes too small, and the usbali property of the composition decreases. If it exceeds 200, the compatibility with other components of the composition decreases. In addition, the viscosity of the composition increases, gold wire deformation and the like are likely to occur, and the printability decreases, and mold stains easily occur.
As described above, it is necessary to use those having a size of 200 or less.

The molar fraction (/ (k ++ m + 2)) of the phenyl group or phenylethyl group modified portion is 0.1 or less, preferably 0.0
In the vicinity of 5, when the silicone-modified phenolic resin curing agent is synthesized, the organopolysiloxane has an appropriate compatibility with the phenolic resin or the organic solvent. The silicone-modified phenolic resin curing agent is suitably used because it has an appropriate compatibility with other components.

The molar fraction of the phenyl group or phenylethyl group modified part is
If it exceeds 0.1, in the composition using the silicone-modified phenolic resin curing agent, the compatibility between the silicone-modified phenolic resin curing agent and other components becomes too good, and the glass transition point and solder heat resistance decrease.

Degree of siloxane polymerization / number of functional groups ((k ++ m + 2) /
m) is a very important parameter, and those having a siloxane polymerization degree / functional group number of 5 or more and 50 or less can improve strength, thermal shock resistance and solder heat resistance without impairing moldability. .

When this parameter is less than 5, in the composition using the silicone-modified phenolic resin curing agent, the compatibility with other components becomes too good, the glass transition point and the solder heat resistance are reduced, and the molecular weight of the silicone reaction part is reduced. Becomes too large, and the viscosity of the composition increases, so that the gold wire deformation easily occurs.

On the other hand, if it exceeds 50, the resin becomes opaque, and the phase separation of the silicone reaction part is apt to occur, whereby the strength, fluidity and printing properties are reduced, and mold stain is liable to occur.

These organopolysiloxanes having an epoxy group-containing organic group can be prepared by subjecting an organohydrogenpolysiloxane and an unsaturated double bond-containing epoxy such as allyl glycidyl ether to an addition reaction in an organic solvent using chloroplatinic acid as a catalyst. can get.

The random copolymerized silicone-modified phenol resin is obtained by using an epoxy group-containing organopolysiloxane and a phenol resin in an organic solvent using one or more catalysts selected from imidazoles, organic phosphines, and tertiary amines. A method of performing a ring-opening addition reaction and the like can be mentioned.

A conventional phenolic resin may be mixed with the obtained random copolymerized silicone-modified phenolic resin and used as a curing agent for the epoxy resin.However, in these mixed systems, the silicone-modified phenolic resin is added to the total amount of the phenolic resin. More than 50% by weight.

If the compounding amount is less than 50% by weight, both the solder heat resistance and the thermal shock resistance decrease and are insufficient. The conventional phenol resin referred to here includes phenol novolak, cresol novolak, and modified resins thereof, and these can be used alone or in combination of two or more.

The phenolic resin used has a hydroxyl equivalent of 80 to 150,
Those having a softening point of 60 to 120 ° C. and containing as little ionic impurities as possible such as Na ⁺ and Cl ⁻ are preferable.

The total epoxy resin component and the total curing agent (phenol resin) component are equivalent ratio of epoxy group / phenolic hydroxyl group = 70/100
A range of ~ 100/70 is preferred.

If the equivalent ratio is less than 70/100 or more than 100/70, the Tg decreases, the hardness at heat decreases, the moisture resistance decreases, and the like, which is unsuitable as a resin composition for semiconductor encapsulation.

Crystalline silica as the inorganic filler used in the present invention,
Examples thereof include fused silica, alumina, calcium carbonate, talc, mica, and glass fiber.

These are used alone or in combination of two or more. Of these, crystalline silica or fused silica is particularly preferably used. In addition, a curing accelerator or the like is used as necessary as a component other than these, and any curing accelerator may be used as long as it promotes a reaction between an epoxy group and a phenolic hydroxyl group, and is generally used for a sealing material. And tertiary amines such as BDMA, imidazoles, 1,8-diazabicyclo [5,4,0] undecene-7 (DBU), triphenylphosphine (TPP), etc. May be used alone or in combination of two or more.

Further, if necessary, a silane coupling agent, a brominated epoxy resin, a flame retardant such as antimony trioxide, hexabromobenzene, a coloring agent such as carbon black and red iron, a release agent such as a natural wax and a synthetic wax, etc. Various additives such as low-stress additives such as silicone oil and rubber may be appropriately blended.

To produce the encapsulating epoxy resin composition of the present invention as a molding material, an epoxy resin, a curing agent, an inorganic filler, a curing accelerator, and other additives are sufficiently uniformly mixed by a mixer or the like, and then further mixed. It can be obtained by melt-kneading with a hot roll or a kneader, cooling, and pulverizing after cooling. These molding materials can be used for sealing, covering, insulating and the like of electronic parts or electric parts.

(Example) Next, an example is described together with a comparative example.

First, 20 parts by weight of an organopolysiloxane and 100 parts by weight of a phenol novolak resin were reacted in the presence of a catalyst in 200 parts by weight of a butanol solvent to obtain silicone-modified phenolic resins (I to H) shown in Table 1.

Example 1 The following composition: Cresol novolak type epoxy resin (Epoxy equivalent: 200, softening point: 65 ° C) 90 parts by weight Brominated phenol novolak type epoxy resin (Epoxy equivalent: 272, softening point: 75 ° C, bromine content: 32%) 10 parts by weight Silicone-modified phenol novolak resin Curing agent (a) 60 parts by weight Fused silica 450 parts by weight Antimony trioxide 25 parts by weight Silane coupling agent 2 parts by weight Triphenylphosphine 2 parts by weight Carbon black 3 parts by weight Carnauba wax 3 parts by weight at room temperature The mixture was thoroughly mixed, then kneaded with a biaxial roll at 95 to 100 ° C., cooled, pulverized, and tableted to obtain an epoxy resin composition for semiconductor encapsulation of the present invention.

This material is molded using a transfer molding machine (molding conditions: mold temperature: 175 ° C., curing time: 2 minutes).
After curing at 175 ° C. for 8 hours, the printability, thermal shock resistance, solder moisture resistance and solder heat resistance were evaluated. Table 2 shows the results.

Examples 2-3 Compounded according to Table 2 and obtained an epoxy resin composition for semiconductor encapsulation in the same manner as in Example 1. Table 2 also shows the evaluation results of the epoxy resin composition for semiconductor encapsulation.

Comparative Examples 1 to 7 Compounded according to Table 2 and obtained an epoxy resin composition for semiconductor encapsulation in the same manner as in Example 1. Table 2 also shows the evaluation results of the epoxy resin composition for semiconductor encapsulation.

* 9 Epoxy resin ESX221 epoxy equivalent 210g / eq, softening point 84 ° C, manufactured by Sumitomo Chemical Co., Ltd. * 10 Epoxy resin ESX222 epoxy equivalent 210g / eq, softening point 85 ° C, manufactured by Sumitomo Chemical Co., Ltd.) Evaluation method * 11 Spiral flow Using a mold for spiral flow measurement according to EMM1-1-66, the length of the molded product when molded at 20 g, molding temperature 175 ° C, molding pressure 7.0 MPa, and molding time 2 minutes. Oh.

* 12 Resin burr length Measure the length of the resin burr at the vent of the obtained molded product.

* 13 Mold stainability Judged by the number of molding shots before mold fogging occurs.

* 14 Marking Use the molded product of the 10th shot, peel off the cellophane tape after marking, and determine the number of stamps when the cellophane tape is removed.

 In the table, the number of peeled seals out of 50 is shown.

* 15 Thermal shock resistance Temperature cycle test of 20 molded products (chip size 36mm ² , package thickness 2.0mm, post-curing 175 ℃, 8Hrs) (150 ℃ ~
-196 ° C), and a 500 cycle test was performed to determine the number of cracked molded products. The table shows the number of molded products in which cracks occurred.

* 16 Life expectancy of solder moisture resistance Sealed test elements are tested at 85 ° C and 85% RH for 72 hours.
After the time treatment, it was immersed in a solder bath at 240 ° C. for 10 seconds, and a pressure cooker test (125 ° C., 100% RH) was performed to measure the open defect of the circuit.

* 17 Solder heat-resistant molded product (chip size 36mm ² , package thickness 2.0mm) 20
After treating each piece under steam of 85 ° C and 85% RH for 72 hours, 24
It was immersed in a solder bath at 0 ° C for 10 seconds, and judged by the number of cracked molded products.

 The table shows the number of molded products in which cracks occurred.

(Effect of the Invention) According to the present invention, it is possible to obtain an epoxy resin composition having high heat resistance, thermal shock resistance and molding processability, which could not be obtained by the prior art, so that the rapid temperature caused by the soldering step Excellent in crack resistance and thermal shock resistance when subjected to thermal stress due to change, so when used for sealing, coating, insulating, etc. of electronic parts and electric parts, especially mounted on surface mount package It is suitable for applications requiring a high degree of reliability, such as thin and highly integrated large chip ICs.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification code FI H01L 23/31 (56) References JP-A-3-220227 (JP, A) JP-A-3-220228 (JP, A) JP-A-3-220229 (JP, A) JP-A-64-73652 (JP, A) JP-A-63-280724 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C08G 59 / 62 C08L 63/00-63/10 C08L 83/10-83/12 H01L 23/29

Claims (1)

(57) [Claims] (A) an epoxy resin (provided that a naphthalene type epoxy resin represented by the following formula (a); Are excluded. (B) A random copolymerized silicone-modified phenolic resin obtained by reacting at least one or more organopolysiloxanes of the following formulas (I) and (II) with a phenolic resin, based on the total amount of the phenolic resin 50-100% by weight phenolic resin curing agent (C) An epoxy resin composition for semiconductor encapsulation, comprising an inorganic filler as an essential component.