KR20040056174A - Non-conductive adhesive composition including silicon intermediate for flip-chip interconnection - Google Patents

Abstract

PURPOSE: A nonconductive adhesive composition containing a silicone intermediate for flip-chip bonding is provided, to improve adhesion reliance, weather resistance, moisture resistance, smear fastness, thermal stability and adhesive strength. CONSTITUTION: The nonconductive adhesive composition comprises 100 parts by weight of an insulating adhesive resin pretreated for removing moisture and volatile impurities; 1-80 parts by weight of a nonconductive filter for improving a thermal stability by lowering a thermal expansion coefficient; and 1-20 parts by weight of a silicone intermediate. Preferably the silicone intermediate is a low molecular weight intermediate having a hydroxyl group, is represented by the formula 1, and has an average molecular weight of 1,000-2,000 and a OH content of 3-5 %, wherein R is a hydrocarbon group of C1-C30.

Description

Non-conductive adhesive composition including silicon intermediate for flip-chip interconnection

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-conductive adhesive for flip chip bonding, and more particularly to a semiconductor device such as an IC or LSI having a non-solder bump on an substrate on which a metal electrode is formed. The present invention relates to a nonconductive adhesive composition suitable for connecting, in particular for flip chip mounting.

As a method of electrically and mechanically connecting semiconductor devices such as IC and LSI to a circuit board on which a metal electrode such as a lead frame, glass or epoxy substrate is formed on the surface, research on flip-chip bonding technology has been actively conducted. ought. In flip chip bonding, a conductive adhesive or a non-conductive adhesive is used as an adhesive for bonding a substrate and a semiconductor element. The conductive adhesive is classified into an anisotropic conductive adhesive and an isotropic conductive adhesive in which conductive particles and an insulating adhesive resin are mixed. On the other hand, the non-conductive adhesive has only a function of physically bonding the semiconductor element and the substrate, and their electrical connection is made by directly connecting the stud bump and the substrate electrode formed on the semiconductor element. Since such a non-conductive adhesive does not contain expensive conductive particles, there is an advantage that the manufacturing cost is low.

1 is a view for explaining a process of flip chip bonding using such a non-conductive adhesive. In order to perform flip chip bonding by using a non-conductive adhesive, as shown in FIG. 1, first, a paste-like non-figure is formed by using a syringe 14 on an upper portion of a substrate 12 on which connection terminals 10 are formed at predetermined intervals. The malleable adhesive 16 is applied. Next, the distance between the gold (Au) stud bump 24 formed on the electrode 22 of the semiconductor chip 20 and the connection terminal 10 formed on the substrate 12 is adjusted, and then the semiconductor chip 20 and When the substrate 12 is heated and pressed, the non-conductive resin adhesive 16 is cured, and the semiconductor chip 20 and the substrate 12 are electrically and physically connected.

As such, the resin adhesive that bonds the semiconductor chip and the substrate should not rapidly evaporate, especially at high temperatures, moisture, volatile impurities, etc. contained in the adhesive or in the connection portion. If the resin adhesive vaporizes at a high temperature, cracks occur in the bonding portion, which causes a decrease in the reliability of the semiconductor device. In addition, conventional resin adhesives for bonding semiconductor chips and substrates are generally sensitive to moisture, and as a result, moisture absorption results in poor connection reliability, weather resistance, adhesive strength, and poor thermal stability. There are disadvantages.

Accordingly, an object of the present invention is to provide a non-conductive adhesive composition for flip chip bonding having good physical properties such as connection reliability, weather resistance, moisture resistance, water resistance, thermal stability, and adhesive strength.

Another object of the present invention is to provide a non-conductive adhesive composition for flip chip bonding, which can not only bond a semiconductor chip and a substrate with high reliability, but also can be economically manufactured.

1 is a view for explaining a process of flip chip bonding using a non-conductive adhesive.

2 is a graph illustrating pressure and temperature conditions applied to a semiconductor chip and a substrate via an adhesive composition during flip chip bonding.

3 is a graph showing a change in connection resistance between a semiconductor chip and a substrate in a high temperature and high humidity conditions in the case of using a non-conductive adhesive according to an embodiment of the present invention and the prior art.

4 is a graph showing a change in connection resistance between a semiconductor chip and a substrate under thermal shock conditions in the case of using a non-conductive adhesive according to one embodiment of the present invention and the prior art.

In order to achieve the above object, the present invention is an insulating adhesive resin having a pretreatment process for removing moisture and volatile impurities; A non-conductive filler for lowering the coefficient of thermal expansion to improve thermal stability; And a non-conductive adhesive composition comprising a silicone intermediate. Here, with respect to 100 parts by weight of the insulating adhesive resin, the content of the non-conductive filler is 1 to 80 parts by weight, the content of the silicon intermediate is preferably 1 to 20 parts by weight, the silicon intermediate has a low molecular weight having a hydroxyl group. As an intermediate of, the average molecular weight is 1000 to 2000, the amount of hydroxyl group (OH content) is preferably 3 to 5%. In addition, the pretreatment process may be performed by heating the insulating adhesive resin for 30 minutes to 2 hours at vacuum conditions and 100 to 150 ℃.

Hereinafter, the present invention will be described in more detail.

The nonconductive adhesive composition according to the present invention includes an insulating adhesive resin, a nonconductive filler and a silicone intermediate, and may further include a coupling agent, a curing agent and / or a curing accelerator, as necessary.

As the insulating adhesive resin used in the nonconductive adhesive composition according to the present invention, thermosetting, thermoplastic, and photocurable resins can be widely used. Preferably, epoxy resins such as bisphenol-A epoxy resins, modified epoxy resins, styrene resins, Styrene-butadiene resin, urethane resin, phenol resin, amide resin, acrylate resin, polyimide resin, polyetherimide resin, ethylene-vinyl resin, acrylonitrile butadiene rubber, silicone resin, acrylic resin and the like alone or mixed Can be used. Such insulating adhesive resin is preferably subjected to a pretreatment process of removing moisture and volatile impurities by a method such as heating under vacuum conditions. The pretreatment process does not particularly limit the conditions as long as it can remove moisture and volatile impurities, but at low pressure, preferably substantially vacuum conditions, at a temperature of about 100 ° C. or higher, preferably 100 to 150 ° C., 30 The pretreatment can be carried out by heating for minutes to 2 hours. In this case, when the pretreatment temperature is less than 100 ° C. or when the pretreatment time is less than 30 minutes, water and volatile impurities cannot be sufficiently removed from the adhesive resin, and when the pretreatment temperature exceeds 150 ° C. or the pretreatment time exceeds 2 hours, The above impurity removal effect cannot be obtained, resulting in deterioration of the resin or economic disadvantage. Moreover, the said adhesive adhesive resin can also use and add usual additives, such as an adhesive represented by rosin, a turbine resin, a gumarodine resin, an antioxidant, a coupling agent, a hardening | curing agent, and a hardening accelerator.

The non-conductive adhesive composition according to the present invention may include a coupling agent for enhancing the adhesive force between the organic adhesive resin and inorganic materials such as glass, metal, and the like. As the coupling agent, 3-glycidoxypropyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane (2- (3,4-epoxy cyclohexyl) ethyltrimethoxysilane) Silane compounds such as 3-glycidyloxypropyl methyldiethoxysilane and titanium compounds may be used, and the amount thereof is preferably 3 to 5 parts by weight based on 100 parts by weight of the insulating adhesive resin. When the amount of the coupling agent is less than 3 parts by weight based on 100 parts by weight of the insulating adhesive resin, there is a fear that the adhesive resin and the inorganic material may not be sufficiently adhered. When the amount of the coupling agent exceeds 5 parts by weight, the effect of improving the adhesive strength of the coupling agent is no longer doubled. Do not.

The curing agent and / or curing accelerator is for promoting the curing of the insulating adhesive resin, and may be used a conventional curing agent such as imidazole-based, acid anhydride-based, amine-based curing agent, the amount is 100 parts by weight of insulating adhesive resin It is preferably from 10 to 50 parts by weight. When the amount of the curing agent and / or curing accelerator is less than 10 parts by weight based on 100 parts by weight of the insulating adhesive resin, curing of the adhesive resin is not sufficiently performed, resulting in a problem of deterioration of physical properties such as adhesive strength and reliability. If it exceeds, there exists a problem that storage stability falls.

The non-conductive filler included in the non-conductive adhesive composition according to the present invention is to improve the thermal stability by lowering the coefficient of thermal expansion of the adhesive composition, as long as the above object is achieved, various known fillers may be used without particular limitation. Examples of non-conductive fillers that can be used in the present invention include boron nitride, silicon oxide, aluminum oxide, titanium oxide, magnesium oxide, aluminum nitride, silicon carbide, talc, calcium carbonate, and the like, and among them, adhesiveness is preferable. Silicon oxide, aluminum oxide, etc. which are excellent and are low in ionic impurities are used. The shape of the non-conductive filler may be flaky, spherical, irregular, or the like. In view of uniform dispersibility, in the case of a paste adhesive, the average particle diameter of the filler is preferably 50 μm or less, and in the case of a film adhesive, the filler It is preferable that the average particle diameter of is 10 micrometers or less. In terms of adhesiveness, workability, etc., the compounding amount of the non-conductive filler is preferably from about 80 parts by weight to 100 parts by weight of the insulating adhesive resin, and the thermal expansion coefficient of the adhesive composition is variously controlled by adjusting the content of the filler within the above weight range. Can be adjusted. When the amount of the non-conductive filler is less than 1 part by weight with respect to 100 parts by weight of the insulating adhesive resin, there is a concern that the thermal stability of the adhesive composition may be lowered, and in the case of the blending exceeding 80 parts by weight, it is difficult to manufacture and handle. .

The silicon intermediate used in the present invention is a low molecular weight intermediate having a hydroxyl group, and has an average molecular weight of 1000 to 2000, an amount of hydroxyl group (OH content) of 3 to 5%, and preferably has the structure of Chemical Formula 1 below.

In Formula 1, the substituent R of the silicon intermediate is a hydrocarbon radical having 30 or less carbon atoms, for example, methyl, ethyl, propyl, isopropyl Alkyls such as butyl, alkenyl such as vinyl, aryl, hexenyl, butenyl, butenyl, and 3-octenyl Alkynyls, such as propynyl, heptynyl, butynyl, 1-penten-3-ynyl, and decinyl Alkynyls such as alkynyl, cyclobutyl, cyclopentyl, cyclohexyl, and cycloaliphatic compounds such as phenyl, tolyl and xylyl Aryl such as aryl, aralkyl such as heptyl, benzyl, and the like. Silicone intermediates that can be used in the present invention can be obtained commercially, for example, the trade name of DOW CORNING Corporation: Z-6018 (OH content 3.9%, average molecular weight = 1600, substituent R = phenyl or propyl). It can be used as the silicon intermediate.

Since the silicon intermediate has a hydroxyl group, it reacts with a wide range of organic resins and monomers through a reaction as in Scheme 1 below. Therefore, incorporating the silicone intermediate into the adhesive composition increases the thermal stability and weather resistance of the adhesive composition.

≡Si-OH + HO-C≡ → ≡Si-OC≡ + H ₂ O

The amount of the silicone intermediate is preferably 1 to 20 parts by weight based on 100 parts by weight of the insulating adhesive resin, and if the amount of the intermediate is less than 1 part by weight, the synergistic effect of moisture resistance and heat resistance may be extremely small. When the amount of use exceeds 20 parts by weight, the physical properties of the resin adhesive may be lowered.

The non-conductive adhesive composition according to the present invention contains the above components, and may be prepared in a film or paste and used for bonding a semiconductor chip and a substrate. In order to prepare the non-conductive adhesive composition paste according to the present invention, first, the insulating adhesive resin is heated in a vacuum state, for example, by vacuum at about 120 ° C. for 1 hour to remove moisture and volatile impurities contained in the resin. do. The non-conductive filler particles and the silicon intermediate are added to the insulating adhesive resin from which moisture and volatile impurities have been removed, and mixed uniformly. At this time, a coupling agent, a curing agent, a curing accelerator, or the like may be added as necessary. Since the mixing process uniformly disperses the solid components and uniformly mixes the high viscosity composition, it is preferable to use a 3-roll mill or a planetary mixer. The non-conductive adhesive composition thus mixed is, for example, contained in a syringe 14, as shown in FIG. 1, to allow metal stud bumps such as Au and Cu, Ni, Cu, and Au bumps 24 to be used. It is used for bonding the semiconductor chip 20 and the substrate 22 on which the back is formed. At this time, the non-conductive adhesive composition according to the present invention is interposed between the substrate and the semiconductor chip, and then, for example, by curing the adhesive composition under pressure and temperature conditions as shown in FIG. Can be.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Example 1

First, a liquid bisphenol-A epoxy resin (YD-128, Kukdo Chemical) is vacuumed at 110 ° C. for about 1 hour to perform a pretreatment step of removing water, volatile impurities, and the like contained in the resin. To 100 parts by weight of the pretreated resin, 10 parts by weight of silicon oxide (silica) was added as a non-conductive filler, uniformly dispersed and mixed using a 3-roll mill, and then a silicon intermediate having a hydroxyl group as an additive (Hydroxy-functional silicon, DOW CORNING, Z-6018) 5 parts by weight, 3-glycidoxypropyltrimethoxy silane ((CH ₃ O) ₃ SiCH ₂ CH ₂ CH ₂ OCH ₂ CHOCH ₃ : DOW CORNING, Z-6040) coupling agent 0.5 weight part and 20 weight part of amine-type hardening | curing agents (AJINOMOTO, PN-23) were put, it fully mixed again using the 3-roll mill, and the thermosetting non-conductive adhesive resin was prepared. The prepared non-conductive resin adhesive paste was placed in a syringe and used for flip chip bonding.

Example 2

A nonconductive resin adhesive paste was prepared in the same manner as in Example 1, except that 20 parts by weight of the silicon intermediate having the hydroxyl group was used.

Comparative Example 1

A nonconductive resin adhesive paste was prepared in substantially the same manner as in Example 1, except that the pretreatment process for removing moisture and volatile impurities from the bisphenol-A liquid epoxy resin was not performed.

Comparative Example 2

A nonconductive resin adhesive paste was prepared in substantially the same manner as in Example 1, except that the silicone intermediate having the hydroxyl group was not used.

After applying the non-conductive adhesive prepared according to the above Examples and Comparative Examples on the FR-4 substrate (125㎛ pitch) and aligned with the gold (Au) stud bump (number of bumps: 296) of the chip, Figure 2 and The bumps were interconnected by heating and pressing under the same conditions to cure the nonconductive adhesive. The connection resistance values of the specimens thus prepared were measured, and the results are shown in Table 1, and the high temperature and high humidity conditions (1000 hours at 85 ° C, 85% RH) and the thermal shock conditions (-55 ° C and 125 ° C for 30 minutes each) The change in the connection resistance value was measured at 500 repeats) to test the reliability, and the results are shown in Tables 1, 3 and 4, respectively. In FIG. 4, the dark solid line represents the temperature and the dim solid line represents the pressure.

Pretreatment of resin Silicon intermediate content (parts by weight) Connection resistance (Ω) Early After high temperature and humidity test Difference (△) After thermal shock test Difference (△) Example 1 O 5 2.8 3.0 0.2 3.3 0.5 Example 2 O 20 2.8 3.1 0.3 3.3 0.5 Comparative Example 1 X 5 2.9 3.5 0.6 4.7 1.8 Comparative Example 2 O X 2.8 4.1 1.3 3.6 0.8

As can be seen from Table 1, Fig. 3 and Fig. 4, the initial connection resistance value is similar to the Example and Comparative Example, but after the specimen is left in a high temperature and high humidity environment, the resistance value of Comparative Example 2 is significantly increased. Can be. In addition, in the case of Comparative Example 1 using a resin that did not remove the moisture and volatile impurities, it can be seen that the connection resistance value is significantly increased as a result of the thermal shock test, and also the resistance value of Comparative Example 2 is also increased compared to the Example. Therefore, the non-conductive adhesive of the present invention performs a pretreatment to remove moisture and volatile impurities from the insulating adhesive resin, and by adding a silicon intermediate having a hydroxyl group, not only excellent moisture resistance, weather resistance and heat resistance, but also excellent thermal stability It can be seen that the connection between the bumps can be formed.

As described above, if the non-conductive resin adhesive is prepared by using an insulating adhesive resin from which moisture and volatile impurities have been removed according to the present invention, and a silicon intermediate having a hydroxyl group is mixed, cracks due to the outflow of moisture and volatile impurities at high temperatures are obtained. The thermal stability can be improved by preventing the phenomenon. In addition, since the silicone intermediate reacts with the resin to increase the thermal stability, moisture resistance, and weather resistance of the resin, it prevents the adhesive strength from being absorbed by water absorption, thereby improving connection reliability between bumps, and providing heat resistance, thereby providing contact resistance. The deviation of is extremely small. In addition, since the non-conductive adhesive composition according to the present invention does not include expensive conductive particles, the chip can be mounted at low cost.

Claims (5)

An insulating adhesive resin which has undergone a pretreatment step of removing water and volatile impurities; A non-conductive filler for lowering the coefficient of thermal expansion to improve thermal stability; And a silicone intermediate. The non-conductive adhesive composition of claim 1, wherein the content of the non-conductive filler is 1 to 80 parts by weight, and the content of the silicon intermediate is 1 to 20 parts by weight based on 100 parts by weight of the insulating adhesive resin. The non-conductive adhesive according to claim 1, wherein the silicon intermediate is represented by the following formula as a low molecular weight intermediate having a hydroxyl group, and has an average molecular weight of 1000 to 2000, and an amount of hydroxyl group (OH content) of 3 to 5%. Composition. In the above formula, the substituent R is a hydrocarbon group having up to 30 carbon atoms. The non-conductive adhesive composition of claim 1, wherein the pretreatment process is performed by heating the insulating adhesive resin for 30 minutes to 2 hours at vacuum conditions and 100 to 150 ° C. The method of claim 1, wherein the insulating adhesive resin is epoxy resin, modified epoxy resin, styrene resin, styrene-butadiene resin, urethane resin, phenol resin, amide resin, acrylate resin, polyimide resin, polyetherimide resin, A non-conductive adhesive composition selected from the group consisting of ethylene-vinyl resins, acrylonitrile butadiene rubbers, silicone resins, acrylic resins and mixtures thereof.