JP2000063452A - Insulating die attach paste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an insulating die attach paste excellent in quick curability, heat resistance, and moisture resistance of adhesion by compounding a specific urethane di(meth)acrylate, a di(meth)acrylate, a phosphoric acid group-contg. (meth)acrylate, an alicyclic epoxidized alkoxysilane, an org, peroxide and/or an azo compd., and an insulating filler. SOLUTION: This paste comprises (A) a urethane di(meth)acrylate obtd. by reacting a hydroxyalkyl(meth)acrylic acid, a polyalkylene glycol, and a diisocyanate, (B) a di(meth)acrylate of formula I, (C) a phosphoric-acid-group- contg. (meth)acrylate of formula II or III, (D) an alicyclic epoxidized alkoxysilane, (E) an org. peroxide and/or an azo compd., and (F) an insulating filler in such wt. ratios that: 0.1<=A/B<=5, 0.001<=(C+D)/(A+B)<=0.05, 0.1<=C/D<=10, 0.01<=E/(A+B)<=0.05 and 0.10<=F/(A+B+C+D)<=0.80.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulating die attach paste for adhering to a semiconductor, which is excellent in quick-curing property and moisture-resistant adhering property.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor package assembling process, a die attach paste has been used for fixing a semiconductor (IC chip) to a lead frame by adhesion so as to prevent chip displacement during wire bonding. The die attach paste includes a conductive paste, particularly a silver paste, for releasing heat and static electricity accumulated in the semiconductor to the lead frame, and an insulating paste that does not require it. The present invention relates to the latter.

Conventionally, it has been a common practice to heat-cure an insulating paste in an oven at a temperature of 150 to 200 ° C. for a time of 1 to 2 hours or more, and many products use an epoxy resin as a base resin. It is on the market. However, with the recent trend toward mass production of computers and cost reduction, it has been required to improve the productivity, and the insulating paste is also required to have a rapid curing property. In this case, the development target is within 15 minutes for oven curing and 1-2 minutes for hot plate curing (in-line cure).

Further, conventionally, as the material of the lead frame, for example, 42 alloy, copper or the like (gold as the surface plating,
Metals such as silver and nickel / palladium have become the mainstream, but recently due to the high performance of computers, BG
A (ball grid array) packages are being widely used. For this reason, the adhesiveness between the chip (semiconductor) and the solder resist (organic substrate) is becoming more important. In this case, it is necessary to cure the material at a temperature of 150 ° C. to 175 ° C. for 15 minutes or less, which requires the development of a new material.

[0005]

SUMMARY OF THE INVENTION The present invention provides an insulating die attach paste which uses an acrylate resin and is excellent in quick-curing properties, heat resistance, and moisture-resistant adhesiveness to organic substrates.

[0006]

Means for Solving the Problems That is, the present invention is a die attach paste in which the following (A) to (F) are essential components and the weight ratio of each is represented by [a] to [f]. (A) Hydroxyalkyl acrylic acid or methacrylic acid, polyalkylene glycol, and urethane diacrylate or methacrylate obtained by reacting diisocyanate, (B) Diacrylate and / or dimethacrylate (C) represented by the general formula (1) Phosphoric acid group-containing acrylate represented by general formula (2) and / or phosphoric acid group-containing methacrylate represented by general formula (3), (D) alicyclic epoxy group-containing alkoxysilane, (E) organic peroxide And / or an azo compound,
And (F) an insulating filler.

[0007]

[Chemical 1]

[0008]

[Chemical 2]

[0009]

[Chemical 3]

[0010] [A] 0.1 ≦ A / B ≦ 5 [B] 0.001 ≦ (C + D) / (A + B) ≦ 0.05 [C] 0.1 ≦ C / D ≦ 10 [D] 0.001 ≦ E / (A + B) ≦ 0.05 [E] 0.10 ≦ F / (A + B + C + D + E + F) ≦ 0.80

[0011]

DETAILED DESCRIPTION OF THE INVENTION Urethane diacrylate or urethane dimethacrylate (component A) used in the present invention is synthesized by a reaction of hydroxyalkyl acrylic acid or methacrylic acid, alkylene glycol and diisocyanate by a conventional method.

Examples of hydroxyalkyl acrylic acid or methacrylic acid are 2-hydroxyethyl acrylate or methacrylate, 2-hydroxypropyl acrylate or methacrylate. Examples of alkylene glycols include propylene glycol and tetramethylene glycol. Examples of diisocyanates include hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate and hydrogenated products thereof.

Examples of the diacrylate and / or dimethacrylate represented by the general formula (1) of the component B include dimethylol tricyclodecane di (meth) acrylate.

The mixing ratio of the components A and B is 0.1 ≦ A / B
It is necessary that ≦ 5. When it is less than 0.1, the curing shrinkage of the paste becomes severe and the chip warps or peels off. On the contrary, when it exceeds 5, the adhesive strength is lowered and the viscosity is remarkably increased.

Next, the phosphoric acid group-containing acrylate represented by the general formula (2) and / or the phosphoric acid group-containing methacrylate represented by the general formula (3) of the component C functions as a coupling agent. Next, the alkoxysilane having an alicyclic epoxy group is, for example, Shin-Etsu Chemical Co., Ltd.
Manufactured by KBM-303 and the like are known. Ingredient C and ingredient D
The total addition amount of 0.0 is 0.0 with respect to the total weight of component A and component B.
It is preferable that 01 ≦ (C + D) / (A + B) ≦ 0.05. If it is less than 0.001, it has no effect on the adhesiveness, and if it is more than 0.05, the viscosity is remarkably increased with the reaction between the components C and D and the adhesiveness is rather lowered.

In the present invention, the components C and D are essential components, and the present invention cannot be embodied even if one of them is missing.
The composition ratio is preferably 0.1 ≦ C / D ≦ 10. 0.1
When it is below the range, the concentration of the alkoxysilane becomes low, and the effect on the adhesive interface decreases. On the other hand, when it exceeds 10, the phosphate group concentration becomes high and acts on the adhesive interface more than necessary, resulting in a decrease in adhesiveness.

It is presumed that the action of the components C and D is such that when they are mixed, the alicyclic epoxy is polymerized to form an oligomer having alkoxysilane in the side chain, and the adhesion to the interface is strengthened. It

Next, as examples of organic peroxides, cumyl peroxyneodecanate, t-butylperoxyneodecanate, 1-cyclohexyl-1-methylethylperoxyneodecanate, 1,1,3 , 3-Tetramethylbutyl peroxyneodecanate, 1,1,3,3-
Tetramethylbutylperoxy-2-ethylhexanate, bis (4-butylcyclohexyl) peroxydicarbonate, t-butylperoxyisopropyl monocarbonate, 1,1-bis (t-butylperoxy)-
3,3,5-trimethylcyclohexane, t-butylperoxybenzoate, t-butylperoxy 3,5
5-trimethylhexanate, t-butylperoxy-
There are 2-ethylhexyl monocarbonate, t-hexyl peroxy-2-ethylhexanate, and the like, and examples of azo compounds include 2,2′-azobisisobutyronitrile and 1,1′-azobis (1-acetoxy). -1-phenylethane) and the like.

These organic peroxides and / or azo compounds may be used alone or in admixture of two or more in order to control the curability. Further, various polymerization inhibitors may be added in advance in order to improve the storage stability of the resin.

The addition amount of these organic peroxides and / or azo compounds is 0.001 ≦ E / (A + B) ≦ 0.0.
It is preferably 5. If it is less than 0.001, the curing rate will be slow, and if it is more than 0.05, the adhesive strength will be reduced due to the reaction between organic peroxides and / or azo compounds, and the pot life of the paste will be unfavorable.

Next, examples of the insulating filler include silica, alumina, aluminum nitride, polyimide and the like, and silica is generally used. The average particle size is 30 μm
The following are preferred. If the average particle size is larger than 30 μm, it is difficult to control the thickness of the adhesive layer, which is not preferable. The amount of addition is 10 to 80% by weight based on the total paste.
It is preferably in the range of. If it is less than 10% or exceeds 80%, it is not preferable in coating workability.

If desired, the resin paste in the present invention may contain additives such as a reactive diluent, a solvent, an antifoaming agent, a surfactant, a thixotropic agent and an elastomer.

The inventor has succeeded in significantly increasing the curing reaction rate by using an acrylate resin as compared with the conventional epoxy resin system. Further, a flexible urethane acrylate resin was mixed in order to reduce the adhesiveness to the organic substrate and the difference in linear expansion coefficient from the organic substrate. In addition, in this acrylate resin system, it was observed that the insulating paste had a significantly lower elastic modulus than that of the silver paste, and thus the adhesive strength could not be obtained, but as a reactive diluent, a difunctional compound having a bulky substituent group ( The phenomenon was prevented by increasing the crosslink density by using (meth) acrylate (in this case, the role of the bulky substituent group is to improve heat resistance, reduce curing shrinkage, etc.). As the coupling agent, it is important to mix the phosphoric acid type coupling agent (component C) and the alicyclic epoxy group-containing coupling agent (component D). This is presumably because the alicyclic epoxy group of component D is ring-opened by the phosphoric acid group of component C, and the product at that time may be involved in improving the adhesiveness.

The present invention will be specifically described below with reference to examples.

[0025]

【Example】 Example 1 Hydroxyethyl acrylate, tetramethylene glycol, isophorone diii Urethane diacrylate obtained by reacting a cyanate (manufactured by Toagosei Co., Ltd. , Aronix M-1600) 50 parts by weight Dimethylol tricyclodecane diacrylate (Kyoeisha Chemical Co., Ltd., DCP -A) 100 parts by weight Phosphate group-containing methacrylate (Nippon Kayaku Co., Ltd., KAYAMER, PM-21)                             1 part by weight Alicyclic epoxyalkoxysilane (Shin-Etsu Chemical Co., Ltd., KBM-303)                         0.5 parts by weight Organic peroxide initiator (NOF CORPORATION, Perhexa 3M)                         1.1 parts by weight

Immediately after adding all of the above raw materials, the mixture was kneaded again by a three-roll mill, and 40 parts by weight of the resulting solution (called varnish) was added to silica filler (Denki Kagaku Kogyo KK).
FB-30, average particle size 6 μm) 40 parts by weight and silica filler (manufactured by Admatics Co., Ltd., SO-25)
R, average particle size 0.5 μm) 20 parts by weight and mixed again 3
Disperse and knead with this roll. Subsequently, defoaming treatment was performed under vacuum to obtain an insulating die attach paste.

The viscosity of the obtained paste was measured at 2.5 rpm using an E type rotational viscometer. Further, after applying the obtained silver paste on an organic substrate, a 6 mm square chip was mounted and cured on a heating plate (170 ° C., 120 seconds) and in an oven (150 ° C. 15 minutes). However, in this case, the organic substrate is bismaleimide-triazine (BT).
Solder resist (Taiyo Ink
Manufactured by PSR-4000 / CA-40) was used. Adhesive strength is room temperature (25 ° C) and heat (200
Automatic shear strength measuring device (made by DAGE, BT)
-100).

Further, the adhesion (at the time of heating) after the sample cured in an oven was subjected to a moisture absorption treatment (temperature 85 ° C./humidity 85% / 72 hours) was also measured. This is an index of long-term reliability of the semiconductor package, and the smaller the decrease in adhesive strength, the better.

The state of chip separation after the actual wire bonding simulation was observed using an ultrasonic flaw detector. The presence or absence of peeling is shown in the table. As a result, the paste prepared by the formulation (mixing ratio) shown in the examples showed sufficient adhesive strength in both oven / hot plate curing, and no chip separation due to wire bonding was observed. Therefore, the semiconductor package has high reliability.

Examples 2-5, Comparative Examples 1-6 An insulating paste was prepared and evaluated in exactly the same manner as in Example 1 except that the compositions shown in the table were used.

[0031]

[Table 1]

[0032]

[Table 2]

Description of compounds in the table Urethane acrylate 1: Urethane diacrylate composed of hydroxyethyl acrylate, tetramethylene glycol and isophorone diisocyanate (Toagosei Co., Ltd.)
Aronix M-1600, manufactured by Co., Ltd. Urethane acrylate 2: Urethane diacrylate containing polyester structure (Aronix M-1100, manufactured by Toagosei Co., Ltd.) Diacrylate 1: Dimethyloltricyclodecane diacrylate (Kyoeisha) Chemical Co., Ltd., light acrylate DCP-A) Diacrylate 2: 1,6-hexanediol diacrylate (Kyoeisha Chemical Co., Ltd., light acrylate 1.6HX-A) Component C: General formula (3) A = 1, b = 1, c = 2 Component D: Alicyclic epoxy group-containing alkoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-303) Polymerization initiator 1: 1,1-bis (t- Butyl peroxy)
3,3,5-Trimethylcyclohexane (NOF Corporation)
-Made by Perhexa 3M) Polymerization initiator 2: Wako Pure Chemical Industries, Ltd.-Made by 2,2'-azobisisobutyronitrile silica 1: FB-30 (Denki Kagaku Kogyo, Ltd., average particle size) Diameter 6 μm) Silica 2: SO-25R (manufactured by Admatics Co., Ltd.,
(Average particle size 0.5 μm)

[0034]

EFFECTS OF THE INVENTION According to the present invention, it is possible to obtain an insulating die attach paste excellent in quick-curing property, heat resistance, and moisture-proof adhesiveness to an organic substrate.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4J027 AG04 AG09 AG12 AG14 AG23                       AG24 AG27 BA02 BA16 BA19                       CA10 CA14 CA15 CA18 CA29                       CA36 CB03 CB09 CC02 CD09                 4J040 FA151 FA152 FA161 FA162                       FA212 FA291 FA292 GA02                       HA306 HB14 HB41 HD35                       JA05 KA03 KA42 LA05 LA07                       NA20                 4J100 AL08R AL09P AL66P AL66Q                       BA03Q BA15R BA39P BA64R                       BC02Q CA05 DA57 FA03                       JA03 JA44                 5F047 AA11 BA33 BB11

Claims (2)

[Claims] 1. An insulating die attach paste having the following components (A) to (F) as essential components and represented by weight ratios [a] to [f]. (A) Hydroxyalkyl acrylic acid or methacrylic acid, polyalkylene glycol, and urethane diacrylate or methacrylate obtained by reacting diisocyanate, (B) Diacrylate and / or dimethacrylate (C) represented by the general formula (1) General formula (2)
And a phosphoric acid group-containing acrylate represented by the general formula (3), (D)
An alkoxysilane having an alicyclic epoxy group, (E) an organic peroxide and / or an azo compound, and (F) an insulating filler. [Chemical 1] [Chemical 2] [Chemical 3] [A] 0.1 ≦ A / B ≦ 5 [b] 0.001 ≦ (C + D) / (A + B) ≦ 0.05 [c] 0.1 ≦ C / D ≦ 10 [d] 0.001 ≦ E /(A+B)≦0.05 [e] 0.10 ≦ F / (A + B + C + D + E + F) ≦ 0.80 2. The die attach paste according to claim 1, wherein the component F is a silica filler having an average particle size of 30 μm or less.