JPH0356526A - Epoxy resin composition for sealing semiconductor - Google Patents

Abstract

PURPOSE:To obtain the subject composition having good moldability, high thermal shock resistance in soldering and high moisture-resistant reliability and suitable for the sealing of semiconductor, IC, LSI, etc., by using a specific epoxy resin, a phenolic curing agent and a large amount of an inorganic filler as main components. CONSTITUTION:The objective composition is composed mainly of (A) an epoxy resin containing (i) a bishydroxybiphenyl-type epoxy resin of formula (R is H or methyl; R<1> to R<8> are H, methyl, ethyl, isopropyl or phenyl; n is 0-5) and (ii) a novolak phenolic resin containing <=5 wt.% of binuclear component at a weight ratio (i/ii) of 30/70 - 95/5 and containing <=0.05 wt.% of hydrolyzable chlorine, (B) a phenolic curing agent (preferably a novolak resin containing <=0.5 wt.% of noncondensed phenolic compound) and (C) 73-90 wt.% (based on the whole composition) of an inorganic filler (preferably fused silica).

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is applicable to the encapsulation of electronic components, especially semiconductors, ICs, LS
This invention relates to an epoxy resin composition suitable for binding materials such as I.

(Prior art) In recent years, transfer molding using epoxy resin compositions has been used to disassemble electronic parts, especially semiconductors, ICs, LSIs, etc., because they are inexpensive, have high productivity, and have relatively well-balanced reliability. The body is the most widely used. However, compared to hermetically stitched molded bodies made of non-water permeable materials such as metal cases and ceramics, the disadvantage is that they are especially inferior in moisture resistance and reliability. This is because after a semiconductor element is pierced with an epoxy resin parabolite, if the molded body is placed in an environment where it is normally used or in an environment with accelerated temperature and humidity, it will gradually absorb moisture, causing fine wiring such as semiconductor elements, especially aluminum. This is because the wiring corrodes, increases leakage current, and eventually breaks.

Sealing with epoxy resin composition O The above-mentioned drawbacks are:
(a) the resin is inherently water permeable, fb)
This is due to the fact that the adhesiveness between lead frames, semiconductor elements, etc. and the resin is not sufficient, (C) the resin contains various impurities, and (d) the epoxy resin is brittle. (a) Since this is an essential drawback of the tlm resin, various improvements have been made mainly to tb+, (C) and (d). +b) a coupling agent, and I
Improvements have been made by adding 73 parts mold release agent, etc., (C) by adding epoxy resins, curing agents, fillers, etc., and (d) by adding various flexibility imparting agents.

However, in recent years, as electronic components have become smaller and thinner, the mounting method for electronic components has shifted from the conventional bottle insertion method to a surface mount method, and even more serious problems have arisen. In the case of the surface mount method, the shape of the molded body has an SOP. QFP
, PLCC, etc. are damaged. When mounting (soldering) on these wiring boards, process at high temperatures of 200 to 300℃ using inert solvent vapor, solder bath immersion, trench or infrared heating furnace. However, the thermal shock at this time will significantly reduce the moisture resistance reliability, and if it does, a crack will occur that reaches the outside.

If the molded body is left in a normal environment until it is mounted, it will absorb moisture, but the rapid temperature rise during mounting will cause the moisture to vaporize and expand explosively, causing damage between the resin and the lead frame, and between the resin and the semiconductor element. This is because interfacial peeling between the two layers may cause cracks in the resin, causing it to explode.

Since such a phenomenon occurs during soldering, it is called solder heat resistance.

Various attempts have been made to improve this solder heat resistance.

On the semiconductor manufacturer side, the shape of the lead frame is devised, the molded body is packaged with a desiccant agent, and on the semiconductor user side, it is dried immediately before use (NIKKKI MICRODEVICE 8198
May 8th issue, page 36, NIKKEI gLEcTRONI
cs June 1988 issue, p. 105). However, these are not preferable because they cause an increase in cost. For this reason, improvements in molding materials have been strongly desired.

On the molding material manufacturer side, high filler filling is used to improve thermal shock resistance (% patent publication No. 61-97322), and thermoplastic resin is added (Japanese patent publication publication No. 62-26081).
5), water-repellent additives and waxes have been used to reduce water absorption, and the stress caused by moisture during mounting has been reduced (Japanese Patent Application Laid-Open No. 60-65023).
I haven't reached a satisfactory level yet. Recently, Talesol Nopolac Eboxy 4i, which has been mainly used
4,4'-bis(2,3-epoxybroboxy), which is new to Ij fats - 3. 3'. 5. 5
'-tetramethylbi7enyl (JP-A-63-2
51419@) method is attracting attention.

The present inventors also focused on this new epoxy gobun and conducted various studies. When ICi is inhibited with an epoxy resin composition using only this epoxy resin, the soldering heat resistance certainly improves, but it suffers from fatal drawbacks such as a low glass transition point, a lot of flakes, and low hardness when heated. I also understood that.

In addition, as semiconductor devices become larger and wiring becomes finer, it is essential to reduce stress. However, due to the increase in the size of semiconductor devices and the miniaturization of interconnections, it is essential to reduce stress.
Certain formability defects such as poor imprintability also require further improvement.

(Problems to be Solved by the Invention) As a result of the inventors' earnest efforts to solve all of these problems, the inventors used two types of epoxy resin gold in combination, and the amount of inorganic filler was t.
It was also observed that when a specific flexibility-imparting agent was used in combination with the adhesive, the solder heat resistance and moisture resistance reliability were greatly improved, and the moldability was also good, thereby completing the present invention. In other words, the present invention maintains good formability when electronic parts, especially semiconductors, ICs, LSIs, etc. are embossed with resin, and significantly improves soldering heat resistance, humidity resistance reliability, and moldability, which were previously unsatisfactory. It is something that improves.

(Means for solving the problem t) The present invention uses a bishydroxybiphenyl-based epoxy resin and a novolak type epoxy resin with a particularly small amount of low-molecular-weight substances, is filled with an inorganic filler of at least f, and more preferably, By adding a specific flexibility-imparting agent, we provide an epoxy resin composition that significantly improves soldering heat resistance and moisture resistance reliability when encapsulating electronic components, etc., and also has good moldability. It is something to do.

That is, the present invention provides a bishydroxypiphenyl epoxy resin represented by the following formula (11 (,'J) (wherein R is a hydrogen atom or a methyl group, Rl to Ra (
, x water atom, methyl group, ethyl group, isoprobyl group,
Seven same or different groups selected from phenyl groups are shown.

The cut n is an integer from 0 to 5. ) (B) Binary component is 5
An epoxy resin (2) containing a novolac-type epoxy resin having a weight f1 or less and gold in a weight ratio of A/B = 30/70 to 95/5, and having a hydrolyzable chlorine content of 0.05 weight f1 or less. Phenol type curing agent (3) Eboxy 44 for semiconductor restraint, whose main component is an inorganic filler or more, which is included in the entire composition at a depth of 73 or more times.
The present invention is an epoxy resin composition for semiconductor manufacturing, which contains a fat composition, the above-mentioned components, a flexibility-imparting agent, and a t main component.

Next, the present invention will be explained in detail.

The epoxy resin II (A) fl used in the present invention is a bishydroxybi7enyl epoxy resin shown below.

(In the formula, R is a hydrogen atom or a methyl group, and R1 to R8 are the same or different groups selected from a hydrogen atom, a methyl group, an ethyl group, an inglovir group, and a phenyl group. n is O 5).) Since the glass transition point decreases as nli increases, it is preferably 0 to 1.0. Specifically, R and R1 to R8 are hydrogen atoms, R is a hydrogen atom, RI H3, R' and UR8 are methic groups, R2
These include those in which R4Rs and B7 are hydrogen atoms.

The other epoxy resin (Blu) is a nopolak type epoxy resin in which the dinuclear component is quintuple fk4 or less.Noporak type epoxy resins include phenol novolak epoxy resin, cresol nopolak epoxy resin, and bisphenol A nopolak epoxy resin. , monohydric or polyvalent phenols, alkylphenols such as butylphenol, flobylphenol, or alkylbenzenes such as ethylbenzene, probylbenzene, etc., in any combination, and novolaks obtained by condensation with formaldehyde under acidic conditions. It also includes epoxy resins obtained by glycidyl etherification.Among these, cresol novolak epoxy resins and phenol novolak epoxy resins are preferred.The binuclear component in ordinary novolac type epoxy resins is usually about 7-fold T4 or more. However, the binuclear component in the novolak-type epoxy 4!! fat used in the present invention is
Five layers:! It needs to be less than or equal to it%. If the weight range is too large, there will be a lot of flaking during molding, and disadvantages such as a low glass transition point of the cured product and low hardness when heated will occur. The epoxy equivalent weight is 160 to 250, especially 160 to 21
0 is good and 1 is bad. And the resin softening point is 50~110℃,
A temperature of 50 to 9 degrees Celsius is particularly preferable. By using such a novolak type epoxy resin in combination, it is possible to improve the moldability, heat resistance, etc., which are the seven drawbacks, without deteriorating the soldering heat resistance improvement effect of bishydroxybiphenyl epoxy resin. It is something that can be used.

The ratio of (4) bishydroxybiphenyl-based epoxy resin and (B) novolac-type epoxy resin combined with purple is 1 [amount ratio A/B is 3 0/7 0 to 95/5]
It must be. (If the amount of N epoxy resin is more than 95% by weight, the glass transition point will be too low and the viscosity will be too low, resulting in a lot of flaking and making it difficult to form the mold. If the amount of hydrolyzable chlorine is too low, the effect of improving soldering heat resistance will be reduced, and the fluidity will be poor.In addition, the less hydrolyzable chlorine in both epoxy resins, the better, but especially the less
．． 05 weight range or less is preferred. This is because if there is more than this, the moisture resistance reliability will be poor. Also, it is better to have fewer water-soluble ions such as sodium ions and chloride ions, especially 5
It is preferably less than ppm. This is because, as in the case of hydrolyzable chlorine, if the amount is more than this, the moisture resistance reliability will deteriorate.

Preferably, the composition of the present invention is flame retardant. For this purpose, halogenated epoxy resins such as brominated bisphenol A-type epoxy resins, brominated phenol novolac epoxy resins, and halogenated products of the above-mentioned bishydroxybiphenyl-based epoxy resins are usually used as halodane compounds. It will be done. These must be 25% or less in weight relative to the entire ebony/pattern fat. The reason why there is more than this is not because it is unnecessary for imparting flame retardancy, but because the soldering heat resistance and moisture resistance reliability are reduced.

As the (2) phenolic curing agent used in the present invention, one having at least two or more hydroxyl groups in one molecule is used. For example, phenol, resorcinol, cresol, xylenol, proylphenol, amylphenol, butylphenol, octylphenol,
Novolac tree Q, which is synthesized from 7-enylphenol, allylphenol, bisphenol A, etc., alone or in combination, as well as polyisopropenylphenol, polyvinylphenols, and phenol-type curing agents in which halogen groups are introduced into these. etc., and one or more types of these may be used. Among these, the uncondensed phenolic compound is less than 1 fold,
Preferably, novolak resin is used in an amount of 0.5% by weight or less. And the softening point is 50-110℃, preferably 6
A temperature of ~90°C is used.

The amount of the curing agent to be blended is such that the ratio of the phenolic hydroxyl group of the curing agent to the epoxy group of the epoxy resin is in the range of 0.3 to 1.2, particularly preferably in the range of 0.4 to 1.1. If it is outside the above range, the moisture resistance reliability and other properties will deteriorate, so it is preferable.

Next, the inorganic filler (3) used in the epoxy resin composition of the present invention includes powders such as crystalline silica, fused silica, talc, alumina, calcium sulfate, calcium carbonate, barium carbonate, and silicon nitride, or glass, and silicon nitride. and silicon carbide fibers and whiskers, and one or more of these may be used. Among these, silica, especially fused silica, is preferred because it has high purity and a low coefficient of thermal expansion. As for the shape, in addition to the usual crushed products, spherical ones are also suitably used.

The blending amount of the filler is required to be at least 76% by weight, preferably at least 75% by weight, with respect to the entire composition, and it is preferably as large as possible as long as moldability etc. are not impaired. Especially when spherical filler is used for all or part of the filler, 8 mouth weight ik
It is also possible to mix more than one. If the weight ratio is less than 73, the soldering heat resistance is insufficient.

Next, examples of the flexibility imparting agent used in the present invention include the following. Rubbery substances such as silicone rubber, polysulfide rubber, butadiene-modified rubber, hydrogenated butadiene styrene rubber 1 or block polymer, thermoplastic elastomer, oily substances such as silicone oil,
Resin-like substances such as various thermoplastic resins and silicone resins,
Alternatively, examples include epoxy resins and phenol resins partially or completely modified with hepta-amino silicone, epoxy silicone, alkoxy silicone, etc.

Among these, particularly preferred are (ω hydrogenated styrene-butadiene block copolymer, hydrogenated styrene-isoprene block copolymer, hydrogenated acrylonitriloptadiene copolymer, and carboxyl, carboxylic acid, and acid anhydride groups). (b) Those with functional groups that can react with epoxy resins or phenolic curing agents, such as trialkoxylyl groups and amino groups; (b) Two or more types that have functional groups that can react with each other, such as amino silicone and epoxy silicone. Reactive silicone gold 1 modified in advance with an epoxy resin or phenol type curing agent, or silicone resin powder can be used.If the above (a) or (b) is used, it not only has good moisture resistance but also good reliability. The molded product can be molded with good moldability without bleeding etc. Also, since the molded product has flexibility imparting agents with good heat resistance, it maintains stable performance even if the molded product is left at high temperatures for a long time. be able to.

The amount of the flexibility imparting agent added is 0.1 of the total composition.
~1 0 i1i: [%, preferredtt, <fl0.3~5f
There is iii-t'. There is no effect if the weight is less than 0.1 kg.
This is because if the weight exceeds 10%, fluidity will decrease and poor moldability such as a large number of bottle holes will occur.

Next, a curing accelerator is added to the epoxy resin composition of the present invention so that the molding can be completed in a short time.

A preferred curing accelerator is 1,8-diazbicyclo(5.4.0)-7-undecene (hereinafter referred to as DBU).
, 6-dibutylamino-1,8-diazbicyclo (5.
4. [)) Undecene-7,7-methyl-1.5.7-
}Ria debicyclo(4,4.0)decene-5, etc., its carboxylates, phenol novolac salts, tri7enyl7
Alkylphosphine such as ossuphine, triethylammonium-tetra7enylboron liquid salt, tetra7enylboronic acid salts such as tetraphenylphosphonium-tetraphenylboronic acid salt, boron compounds such as triphenylphosphine and triphenylboron, triphenylphosphine, etc. Enylphosphine ● Complex compounds such as triethoxyaluminum, penzotriazolate salts such as tetrabutylphosphonium pendetriazolate, tetra-n-butylphosphonium, O,O-dietherphosphorodithioate, imida r
One type or two or more types can be used in one type. The amount of these added is usually 0.1 to 5% based on the total amount of epoxy resin.
It is excellent in weight.

The epoxy resin composition of the present invention may optionally contain carnapa wax, montan wax, higher fatty acids and their calcium salts, fluorine compounds, polyethylene wax,
Mold release agents such as solid casing or oily silicone, flame retardant aids such as antimony trioxide and antimony pentoxide, coloring agents such as carpon black, r-glycidoxyprobil
Coupling agents such as trimethoxysilane, r-aminopropyl triethoxysilane, r-mercaptoglobin triethoxysilane, and ureidoglobil triethoxysilane can all be added and blended as appropriate.

In order to improve the heat resistance of this composition, it is also preferable to blend an imide compound such as bismaleimide or the like.

The composition of the present invention can be produced by mixing the above-mentioned materials in a blender or mixer, melt-kneading them in a heated roll case or seconder, and then cooling and pulverizing them.

(Example) Next, Examples of the present invention will be shown, and all parts below indicate parts by weight.

/3 Example 1-JE! ．． and Comparative Examples 1 to 4 Each material shown in Table 1 was weighed in the proportions shown in Tables 2 and 3,
The mixture was mixed with a mixer, further kneaded with a heating roll, and then cooled and ground to obtain an epoxy resin composition.

The silicone-modified phenol resin used in the examples was obtained as follows. After heating and melting 200 parts of the same phenolic novolac resin used in the above example at 140°C, dimethyl silicone oil 31 having an epoxy base side branch having an epoxy equivalent of 2,500 and a molecular weight of about 12,000 was prepared.
and 19 parts of dimethyl silicone oil containing amino groups at both ends with a molecular weight of about 4,000 and a molecular weight of about 4,000 were added and dispersed by stirring at high speed. I let it happen. After reacting for another 6 hours, the mixture was taken out, cooled, and ground for use. The amount added in Examples is shown as the net amount of silicone.

These compositions were evaluated by the following method. The results are shown in Tables 4 and 5.

1) Moldability Flowability was compared using spiral flow at 170°C. Transfer molding was performed using a mold having a gap of 2.5, 1 and 0.30 μm, and comparison was made based on the average value of the length of the gap appearing in the gap.

2) A lead frame with solder heat resistant 6-pin silicon chips glued to the stage was transfer molded with each composition, and an 8-pin Q
FP molded gold was obtained. Next, After Cure, 85°
After absorbing moisture for 96 and 120 hours under conditions of C, 85% RF, it was exposed to fluorine solvent vapor at about 215°C for 60 seconds. The exterior of these packages was examined using a microscope, and the interior was observed using an ultrasonic imaging inspection system IT (manufactured by Hitachi Construction Machinery Co., Ltd.) to check for external and internal cracks. The number of packages was 10 each.

3) Moisture resistance reliability Each composition was transfer-molded onto a 16-pin DIP silicon element for evaluation having aluminum wiring facing each other. After the after-cure, the molded body was immersed in a solder bath at 260°0 for 10 seconds, and the molded body was placed under saturated pressurized steam at 125°C with a bias of 20V applied to accelerate the moisture resistance. I took the Schaaktukar Test (hereinafter referred to as BPCT). Twenty devices were used in each test, and changes over time in the number of devices that developed open defects due to corrosion of the aluminum wiring were investigated.

Table 3. Compounding ratio (numbers represent parts by weight) In addition to the above ingredients, all compositions contained 3 parts of mold release agent, 10 parts of pheasant combustion aid, and 2 parts of carbon plaque.Table 5. Physical properties Note 1: The number indicates the number of packages with no cracks inside or outside, and the time indicates the moisture absorption time.

Note 2 The number is the number of elements with open defects.

(Effects of the Invention) As is clear from the above examples, the epoxy resin composition used for inhibiting semiconductors of the present invention has good moldability,
Since it is resistant to thermal shock during soldering and has significantly good moisture resistance reliability, it has characteristics that make it suitable for electronic components, particularly semiconductors, ICs, LSIs, etc.

Claims (1)

[Claims] 1. (1) (A) A bishydroxybiphenyl epoxy resin represented by the following formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula, R is a hydrogen atom or a methyl group, (B) Contains a novolac type epoxy resin in which the binuclear component is 5% by weight or less in a weight ratio of A/B = 30/70 to 95/5, and has hydrolyzable chlorine of 0.05% by weight or less. Epoxy resin (2) Phenol type curing agent (3) An epoxy resin composition for semiconductor encapsulation, the main components of which are an inorganic filler and an inorganic filler contained in an amount of 76% by weight or more based on the entire composition. 2. An epoxy resin composition for semiconductor encapsulation, the main components of which are the composition according to claim 1 and a flexibility imparting agent. 3. Claim 2, wherein the flexibility imparting agent is at least one selected from hydrogenated styrene-butadiene block copolymer, hydrogenated styrene-inprene block copolymer, hydrogenated acrylonitrile-ptadiene copolymer, and silicone resin powder. The epoxy resin composition for semiconductor encapsulation described above.