JP3378492B2 - Capsule type flame retardant and resin composition for encapsulating semiconductor containing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an encapsulating flame retardant having excellent flame retardancy and excellent curability that does not cause curing inhibition when a resin component undergoes a curing reaction, and a semiconductor encapsulating agent containing the same. It relates to a resin composition.

[0002]

2. Description of the Related Art In recent years, electronic parts such as semiconductor devices are required to have high safety and flame retardancy. Thermosetting resins such as epoxy resins and polyester resins are mainly used as such molding materials, and a combination of bromine and antimony has been frequently used as a flame retardant.

However, bromine is a problem because it is feared that harmful substances will be generated during combustion and antimony is toxic. Therefore, there is a demand for the development of a flame retardant that is environmentally and safety-free.

For example, Japanese Unexamined Patent Publication (Kokai) No. 8-151505 exemplifies a combination system of a red phosphorus flame retardant and a boron flame retardant as debromination and antimony removal. In addition, Japanese Patent Laid-Open No. 7-1
According to Japanese Patent No. 65773, a phosphorus-containing compound is added to the base resin of a molding material to make it flame-retardant. However, although it has become possible to impart flame retardancy to materials other than bromine and antimony, none of them has been put to practical use because of the poor balance of various characteristics.

There is a microencapsulation of a flame retardant for the purpose of improving such characteristics. JP-A-55-11898
Japanese Unexamined Patent Publication No. 8 discloses a method of encapsulating a flame retardant with acrylonitrile, vinylidene chloride, acrylic acid or the like and using the suspension polymerization method to form particles. In addition, JP-A-4
JP-A-249550 discloses a method of encapsulating an organic halide flame retardant with a thermoplastic resin.

Further, in Japanese Unexamined Patent Publication No. 8-91813, a red phosphorus flame retardant is used as a core substance, and a composition composed of a resin and bismuth oxide or bismuth hydroxide is used as a film material, and the impact method in a high-speed air stream is used. A method of encapsulation is disclosed.

However, JP-A-55-118988
Since the granular material obtained in the publication has a structure in which a flame retardant is dispersed in a resin which is a film material, there is a problem that the flame retardant carried on the film material is easily separated. In addition, JP-A-4-2495
According to the publication No. 50, since the capsule membrane material is a thermoplastic resin such as rubber, gelatin, cellulose, acryl, or polyolefin resin, the membrane material is softened or melted when heated and the flame retardant is easily released. .

In Japanese Patent Laid-Open No. 8-91813, the interfacial adhesion between the resin in the encapsulating film material and the bismuth-based particles is insufficient, so that water penetrates through the surface of the particles and phosphoric acid, phosphorous acid, etc. Ionic substances are generated, and there is a problem in moisture resistance reliability.

In any of the above conventional techniques, the flame retardant is desorbed from the capsule when heated. Therefore, in a resin composition based on an epoxy resin such as a semiconductor encapsulant, there is a problem in that the catalytic activity is lowered due to the contact between the flame retardant and the curing accelerator, and curing inhibition occurs.

[0010]

The above-mentioned prior art is considerably effective in improving flame retardancy. However, in these compositions, the core substance is easily desorbed from the film material during heat-molding and curing, so that curing inhibition occurs due to contact with the resin component.

An object of the present invention is to provide a capsule-type flame retardant which has excellent flame retardancy without using antimony and does not impair the mold-curability of a molded article using the same, and a semiconductor containing the same. It is to provide a resin composition for sealing.

[0012]

Means for Solving the Problems As a result of intensive studies on encapsulation of a flame retardant, the present inventors have used a flame-retardant substance as a core substance and a thermoplastic resin or a thermosetting resin as a film material. The desired capsule-type flame retardant could be obtained by encapsulating it.

The constitution is a capsule type flame retardant composed of a core substance and a film material, wherein the core material has a flame retarding action, and the film material has a flexural modulus at 30 ° C. of 2000 kg / m.
A capsule-type flame retardant characterized by comprising an organic material of m ² or less, preferably 50 to 2000 kg / mm ² .

The core substance is not particularly limited as long as it is solid at 30 ° C. or lower and has flame retardancy.

Even if the capsule-type flame retardant is added to the epoxy resin composition, the flame retardant is less likely to come into direct contact with the curing accelerator due to encapsulation, so that inhibition of the curing reaction can be suppressed. When the resin composition using the same is ignited, the flame retardant is released from the film material of the capsule to exert a flame retarding effect, and the fire is extinguished.

Further, since the flame retardant is coated with a film material, it does not adversely affect the physical properties of the cured product, so that the reliability of the cured product can be greatly improved.

The flame retardancy of the present invention is exhibited at a temperature higher than the molding temperature (for example, about 200 ° C.) of the molding material using the same, so that it is excellent in mold curability and has a balance of various properties. A good cured product can be obtained. Therefore, various molded products of the resin composition using the capsule flame retardant of the present invention can greatly improve various reliability.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The capsule-type flame retardant of the present invention is produced by a high-speed air current impact method. That is, after mixing both the core substance and the membrane material, when appropriate mechanical energy is applied, the core substance and the membrane material adhere to each other, and further the membrane material softens or melts to cause surface fusion with the core substance, resulting in a capsule type difficulty. A burnout is obtained.

The structure of the capsule-type flame retardant particles has a sea-island structure composed of one or more core substances and film substances as shown in the schematic sectional view of FIG. Further, the coating rate of the film material with respect to the core substance of the capsule-type flame retardant, which surrounds or carries a plurality of core substances, must be 30% or more.

As the capsule-type flame retardant, a known flame-retardant substance which is solid at room temperature can be used. For example, there are bromine flame retardants, chlorine flame retardants, phosphorus flame retardants, inorganic flame retardants, and the like.

Typical of brominated flame retardants are epoxy resins having two or more epoxy groups in one molecule.
Examples of chlorine-based flame retardants include chlorinated paraffin and perchlorocyclodecane. Examples of phosphorus flame retardants include phosphoric acid ester compounds such as tris (chloroethyl) phosphate and tris (dichloropropyl) phosphate, and red phosphorus.

Further, there are iron oxide-based, tin oxide-based, zinc oxide-based, titanium oxide-based, and molybdenum oxide-based metal oxides. Also, aluminum hydroxide, magnesium hydroxide,
Dawsonite, calcium aluminate, calcium hydroxide, zinc borate, kaolin clay, calcium carbonate,
Examples thereof include ammonium molybdate.

The film material used for the capsule-type flame retardant includes epoxy resin, phenol resin, polyester resin, urethane resin, methacrylate resin, olefin resin, styrene resin, acrylic resin, vinyl chloride resin, and the like. Can be used after being crosslinked as necessary. When using these resins, known compounds that can react with the resins can be used. Epoxy resin or acrylic resin is particularly preferable.

Further, as an accelerator, an imidazole-based compound,
Known amine-based or phosphorus-based compounds can be used.

A rubber-like substance such as silicone is added to the semiconductor encapsulating material for the purpose of lowering the elastic modulus. The capsule-type flame retardant of the present invention is provided with flame retardancy and low elastic modulus. Flexural modulus at 30 ℃ is 2000kg
The reason why the film material having a thickness of / mm ² or less is used is to relax the curing shrinkage strain of the molding material and the thermal strain in the heat cycle test of the molded product. Flexural modulus is 2000 kg / mm
^When the film material exceeds ² , the effect of reducing various strains becomes small, and further, the film material becomes hard and brittle, and the film material is easily broken.

In the particle structure of the capsule-type flame retardant, the core material is surrounded by the membrane material, and the core material and the membrane material have a sea-island structure. The morphology is as follows: (1) The core material is surrounded or supported by a film material, respectively. (2) In the particles of the capsule-type flame retardant, the coverage of the film material on the entire surface of the particle is 30% or more. 3) In the particles of the capsule type flame retardant,
It may be composed of a plurality of core substances having different components.

The flame retardant contained in the capsule type flame retardant of the present invention is 10 to 95% by volume, preferably 20 to 8%.
It is in the range of 0% by volume. If it is less than 10% by volume, the effect of imparting flame retardancy is small, and it is necessary to add a large amount of microcapsule-type flame retardant. Therefore, the physical properties of the cured product change significantly, and desired properties cannot be obtained.

If it exceeds 95% by volume, the flame retardancy can be sufficiently exhibited, but the film of the film material becomes too thin and the film strength is lowered, so that the film is broken and the flame retardant is released in the manufacturing process of the molding material. As a result, the curing reaction is hindered during curing, resulting in deterioration of the physical properties of the cured product.

The film material composition of the microcapsule type flame retardant comprises a thermosetting resin having a melting point or softening point of 40 ° C. or higher,
It is a photocurable resin and a thermoplastic resin. When the final capsule-type flame retardant product is used, the film material can be crosslinked to further increase the heat resistance. However,
If the melting point or softening point is lower than 40 ° C., the film material is deformed and damaged during the production or molding of the molding material, the flame retardant is released, and curing is inhibited, and the physical properties of the cured product are deteriorated.

An inorganic filler is blended with the molding material for electronic devices and the like. As such an inorganic filler, fine powder of fused silica, crystalline silica, alumina, calcium carbonate, zirconium silicate, calcium silicate, talc, clay, mica and the like can be used. The content of the inorganic filler is preferably 10 to 90% by volume with respect to the entire resin composition.
These inorganic fillers are added for the purpose of improving the thermal expansion coefficient, thermal conductivity, elastic modulus, etc. of the cured product, and if the blending amount is less than 10% by volume, sufficient properties cannot be obtained.
On the other hand, if it exceeds 90% by volume, the melt viscosity of the molding material will rapidly increase and the fluidity will decrease, so that a stable molded article cannot be obtained.

The reason why the capsule type flame retardant of the present invention has excellent flame retardancy and mold curability is considered as follows.

In the core substance surrounded or supported by the particles of the capsule-type flame retardant, the coverage of the film material is 30%.
That is all. When this is added to the molding material, the contact point with the curing accelerator contained in the molding material becomes extremely dilute, so the activity of the curing accelerator is hardly reduced, and the effect on the curing reaction is Few. Moreover, as soon as the composition molded article is ignited, the flame retardant is released from the film material,
Develop digestive action. Therefore, the molding material containing the capsule-type flame retardant of the present invention has both excellent mold curability and flame retardancy.

The film coverage was obtained by observing the capsule-type flame retardant particles from an observation photograph of a scanning electron microscope, and shown as an average value of 10 capsule-type flame retardant particles.

[0034]

EXAMPLES The present invention will be specifically described based on examples.

[Examples 1 to 6] Capsule-type flame retardants were prepared as follows. Flame retardant 10-15 listed in Table 1
0 g and 10 to 100 g of the film material were blended, and a capsule type flame retardant was produced by a mechanofusion system (manufactured by Hosokawa Micron). The conditions are a rotation speed of 1000 to 2500 rpm and a temperature of 25 to 100 ° C.

The acrylate resin has a glass transition temperature of 60.
Polymethylmethacrylate (Soken Kagaku) at ℃ was used.

Next, 100 g of o-cresol novolac type epoxy resin (Sumitomo Chemical, epoxy equivalent 195) / phenol novolac resin (Meiwa Kasei, hydroxyl equivalent 10)
6) 55 g / triphenylphosphine (Hokuko Kagaku) 1.
A composition of 6 g was mixed and melted at about 80 ° C. to obtain an epoxy resin composition. This epoxy resin composition is 10-50
What was finely pulverized to μm was used as a film material.

The properties of the thus obtained capsule type flame retardant are shown in Table 1. Next, the composition containing the capsule-type flame retardant shown in Table 2 was kneaded with a biaxial mixing roll at about 60 to 100 ° C., cooled and pulverized to obtain an epoxy resin composition for semiconductor encapsulation. A flame-retardant test piece having a thickness of 1.6 mm was molded from this epoxy resin composition by a transfer press (mold temperature: 180 ° C., pressure: 7 MPa, molding time: 90 seconds).

Table 3 shows the evaluation results of the curability and flame retardancy of the obtained epoxy resin composition. Further, FIG. 2 shows the relationship between the coverage of the film material and the curability (gelling time). Furthermore, flexural modulus and heat cycle test (-50 ℃ ~
Table 4 shows the incidence of defective adhesion with the aluminum foil at + 100 ° C.

The coating rate of the film material of the capsule type flame retardant was determined as follows. As shown in the schematic cross-sectional view of FIG. 1, the flame retardant 1 has a particle form of 100% coverage.
Particles completely covered with a membrane material [Fig. 1
(A)], a plurality of flame retardants are contained in a coating material to form one particle [Fig. 1 (b)]. The case like this schematic sectional view was set to 100% coverage. In addition, the measurement of the coverage was obtained from a scanning electron microscope photograph.

The curing characteristics were measured using a curast meter. The temperature was 180 ° C., and the curability was evaluated by the time from when the reaction started to when the curast stress reached 80% of the maximum value.

The flame retardancy test was carried out according to the UL94 vertical test (sample thickness: 1.6 mm). The results are shown in Table 3. Further, a resin-sealed semiconductor device was molded and the following mounting test was conducted.

The solder reflow resistance test was conducted by using a silicon chip (6 with aluminum zigzag wiring formed on the surface).
(mm x 6 mm) mounted on a 42 alloy lead frame, and a semiconductor device (20 x 14 mm x thickness 2 mm) in which the aluminum electrode on the chip surface and the lead frame are wire-bonded with a gold wire (φ30 μm) is resin-sealed. Then, it was post-cured at 180 ° C. for 10 hours.

For the reliability test of solder reflow resistance, this resin-encapsulated semiconductor device was left at 85 ° C./85% RH for 168 hours, and then heated in an infrared reflow oven at 240 ° C. for 90 seconds to generate a package crack. Was checked for.

For the humidity resistance reliability test, a surface mounting type QFP element (tab 6.7 × 6.7 mm) was used, and 65 ° C., 95% R
After being left under high temperature and high humidity of H for 72 hours, vapor reflow at 215 ° C./90 seconds and immersion in salt water were performed. Furthermore, after leaving these elements under the condition of 95% RH for 500 hours,
The number of elements in which aluminum corrosion occurred was examined.

In the high-temperature storage test, a resin-sealed semiconductor device of the same type as that used in the humidity resistance test was left in a thermostatic chamber at 200 ° C. for 200 hours to examine the bonding failure between the gold wire and the aluminum wiring. The results are shown in Table 5.

[0047]

[Table 1]

[0048]

[Table 2]

[0049]

[Table 3]

[0050]

[Table 4]

[0051]

[Table 5]

[Comparative Examples 1 to 4] Capsule-type flame retardants were prepared in the same manner as in Examples, but the same except that the coverage of the film material was small. The molding conditions and various evaluation methods are the same as those in the above-mentioned examples. The results are also shown in Tables 2, 3 and 5.

[0053]

The capsule-type flame retardant of the present invention imparts excellent flame retardancy when incorporated into a resin composition. Moreover, when applied to a resin-sealed semiconductor device, excellent reliability can be obtained.

Further, a highly reliable material can be provided by blending it with a molding material for various electronic devices.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of one particle of a capsule type flame retardant.

FIG. 2 is a graph showing the relationship between the coverage of the capsule flame retardant film material and the gelation time.

[Explanation of symbols]

1 ... Core substance, 2 ... Membrane material.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasue Sugawara 1-1-1 Omika-cho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi Research Laboratory (72) Inventor Takumi Ueno 7-1 Omika-cho, Hitachi-shi, Ibaraki No. 1 Hitachi Ltd. in Hitachi Research Laboratory (72) Inventor Toshiya Sato 7-1-1 Omika-cho, Hitachi City, Ibaraki Prefecture Hitachi Ltd. Hitachi Research Laboratory (72) Inventor Toshiaki Ishii 7-chome Omika-cho, Hitachi City, Ibaraki Prefecture No. 1-1 Hitachi Ltd. in Hitachi Research Laboratory (72) Inventor Ryo Mogi 7-1-1 Omika-cho, Hitachi City, Hitachi, Ibaraki Hitachi Ltd. Hitachi Research Laboratory (72) Inventor Masahiko Ogino Omika-cho, Hitachi City, Ibaraki Prefecture 7-1-1 No. 1 Hitachi Research Laboratory, Hitachi, Ltd. (56) Reference JP-A-4-370159 (JP, A) Kaihei 1-96255 (JP, A) JP 6-80882 (JP, A) JP 9-151378 (JP, A) JP 61-115942 (JP, A) JP 51-150553 ( JP, A) JP-A-7-252380 (JP, A) JP-A-4-249550 (JP, A) JP-A-6-271745 (JP, A) JP-B 47-6496 (JP, B1) (58) ) Fields surveyed (Int.Cl. ⁷ , DB name) C08L 1/00-101/16 C08K 3/00-13/08 C09K 21/14 H01L 23/29-23/31

Claims (5)

(57) [Claims] 1. Aluminum hydroxide, magnesium hydroxide
And a core material having flame retardant action selected from zinc borate ,
Made of a film material composed of an organic material with a flexural modulus at 30 ° C of 2000 kg / mm ² or less ,
A capsule-type flame retardant characterized by being manufactured using an impact method . 2. The capsule-type flame retardant according to claim 1, wherein the particle structure of the capsule-type flame retardant has a sea-island structure in which one or more core substances are surrounded or supported in a film material substance. 3. The capsule-type flame retardant according to claim 1, wherein the particles of the capsule-type flame retardant have a film material coverage of 30% or more with respect to the core substance. 4. The capsule-type flame retardant according to claim 1, wherein the organic material forming the film material of the capsule-type flame retardant is an epoxy resin or an acrylic resin. 5. Aluminum hydroxide, magnesium hydroxide
And a core material having flame retardant action selected from zinc borate ,
Made of a film material composed of an organic material with a flexural modulus at 30 ° C of 2000 kg / mm ² or less ,
A resin composition for semiconductor encapsulation, comprising a capsule-type flame retardant produced by an impact method .