JP3408744B2 - Epoxy resin composition for optical semiconductor encapsulation and optical semiconductor device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical semiconductor device and an optical semiconductor encapsulating epoxy resin composition used for manufacturing the same.

[0002]

2. Description of the Related Art As an encapsulating method for electronic parts such as semiconductor devices, encapsulation with an epoxy resin composition is widely used. As a method of sealing with this epoxy resin composition,
Transfer molding is generally performed because it is excellent in workability and mass productivity.

Incidentally, an epoxy resin composition for optical semiconductor encapsulation (hereinafter referred to as encapsulating resin) used for manufacturing an optical semiconductor device such as a phototransistor, a photodiode, an LED, a CCD, an EPROM which emits light and receives light. ) Is required to have excellent transparency, adhesion, heat resistance, humidity resistance reliability, electrical insulation, and the like.

Further, when repeatedly sealed by transfer molding, a cured product of a sealing resin (hereinafter referred to as a cured resin product)
Since the mold and the mold may adhere to each other and become difficult to separate, the sealing resin is also required to have excellent mold releasability.
It has been studied to improve the mold releasability of a mold and a resin cured product by adding a mold releasing agent such as carnauba wax or montanic acid wax to the sealing resin.

In the case of a sealing resin used for manufacturing an optical semiconductor device, it is particularly important that it has excellent transparency. Therefore, it is necessary to improve the releasability while satisfying the transparency, and therefore it is necessary to use a release agent compatible with the sealing resin. The agent has a problem that the releasability and the moisture resistance reliability are insufficient.

Therefore, before transfer molding,
It has been considered to improve the mold releasability from the mold by supplying a fluorine-based or silicon-based mold release agent to the surface of the mold by spraying or coating and then performing transfer molding. However, in the case of the transfer molding method in which such a mold release agent is supplied to the surface of the mold, it takes time to supply the mold release agent to the surface of the mold, resulting in a longer molding cycle and increased productivity. Is low, and in order to uniformly supply the mold release agent to the surface of the mold, it is generally necessary to include a solvent in the mold release agent, and the problem that this evaporation of the solvent may cause environmental deterioration was there.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and its purpose is to contain an epoxy resin, a curing agent, a curing accelerator and a release agent. It is an encapsulating resin (epoxy resin composition for encapsulating optical semiconductors), and even when repeatedly encapsulating, the mold and the resin cured product are excellent in releasability, and transparency and moisture resistance reliability are high. It is an object of the present invention to provide an encapsulating resin that gives an excellent cured resin.

It is another object of the present invention to provide an optical semiconductor device which is excellent in mold releasability from a mold and is excellent in transparency and moisture resistance reliability.

[0009]

The encapsulating resin (epoxy resin composition for optical semiconductor encapsulation) according to claim 1 of the present invention is an encapsulating resin containing an epoxy resin, a curing agent, a curing accelerator and a release agent. In the stop resin, a compound having a weight fraction of a structural portion represented by the following formula (a ) and represented by the following formula (c) of 40 to 90% by weight is contained as a release agent. And

[0010]

[Chemical 2]

The encapsulating resin according to claim 2 of the present invention is the encapsulating resin according to claim 1, wherein the compound represented by the formula (a ) has an average molecular weight of 500 to 3000. To do.

An optical semiconductor device according to claim 3 of the present invention is
A semiconductor chip is sealed with the sealing resin according to claim 1 or 2.

The compound represented by the above formula (a ) and having a weight fraction of the structural portion represented by the above formula (c) of 40 to 90% by weight becomes cloudy when mixed with an epoxy resin or the like. Since it is a compound that is difficult and does not easily reduce the moisture resistance reliability, the use of the sealing resin according to the present invention provides a cured resin product having excellent transparency and moisture resistance reliability. Furthermore, since this compound also has a releasing property, it is possible to perform sealing with excellent releasing property between the mold and the resin cured product.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The encapsulating resin according to the present invention is represented by the above formula (a ) as at least an epoxy resin, a curing agent, a curing accelerator, and a release agent, and is represented by the above formula (c). It comprises a compound having a weight fraction of the structural portion represented by 40 to 90% by weight (hereinafter, referred to as A compound).
It is important to contain this A compound, and when it is not contained, the mold releasability between the mold and the resin cured product is lowered when repeatedly sealed, and the obtained resin cured product is It tends to become cloudy and the transparency is lowered, or the moisture resistance reliability of the obtained resin cured product is likely to be lowered.

When the weight fraction of the structural part represented by the above formula (c) is less than 40% by weight, the transparency of the cured resin tends to be lowered, and when it exceeds 90% by weight, it is separated. The moldability is likely to be lowered, and the moisture absorption of the resin cured product is increased, so that the moisture resistance reliability and the like may be lowered. In addition,
The weight fraction of the structural portion represented by the formula (c) represents the ratio of the molecular weight of the structural portion represented by the formula (c) to the molecular weight of the A compound, and for example, the molecular weight of the A compound is 14
00, the molecular weight of the structural part represented by the formula (c) is 700
In the case of, it becomes 50% by weight.

The compound A has an average molecular weight of 500 to
When it is 3,000, stable releasability and transparency are obtained, which is preferable. If it is less than 500, the releasability tends to decrease, and if it exceeds 3000, the transparency of the resin cured product tends to decrease.

Further, the compounding amount of the compound A is preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the sealing resin. If the amount is less than 0.1 parts by weight, the effect of improving the releasability between the mold and the resin cured product is small.
If it exceeds the weight part, the transparency of the resin cured product may be easily reduced, or the adhesive strength of the semiconductor chip and the resin cured product may be reduced to lower the moisture resistance reliability and the like.

The release agent is not limited to the one containing only the compound A, and may be natural carnauba or the above formula () as long as the object of the present invention is not impaired. Although represented by a), a compound in which the weight fraction of the structural portion represented by the above formula (c) is less than 40% by weight may be added.

The epoxy resin used in the present invention includes:
It is not particularly limited as long as it contains an epoxy resin having two or more epoxy groups in the molecule. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, orthocresol novolac type epoxy resin. , Phenol novolac type epoxy resin, biphenyl type epoxy resin, alicyclic epoxy resin, linear aliphatic epoxy resin, heterocyclic epoxy resin, triglycidyl isocyanurate, and the like. You may use together the above. It is preferable to use an epoxy resin that is relatively less colored as the epoxy resin to be used because the cured product of the resin is excellent in transparency.

The curing agent used in the present invention is not particularly limited as long as it cures by reacting with an epoxy resin, and examples thereof include hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, and tetrahydrophthalic anhydride. Examples thereof include acid anhydrides and the like, and novolac resins obtained by condensation reaction of phenol, cresol, xylenol, resorcin and the like with formaldehyde. The above curing agents may be used alone or in combination of two or more. It should be noted that it is preferable to use a curing agent having relatively little coloring as the curing agent to be used because the cured resin product has excellent transparency. An amine-based curing agent may be added, but when an amine-based curing agent is used, coloring of the resin cured product generally becomes large. Therefore, it is necessary to pay attention to the amount of the composition when used. . The amount of the curing agent is generally 0.5 to 5 in terms of an equivalent ratio to the epoxy resin.
About 0.7 to 1.3 is preferable.

The curing accelerator used in the present invention is not particularly limited as long as it accelerates the reaction between the epoxy resin and the curing agent, and examples thereof include organic phosphine compounds such as triphenylphosphine and diphenylphosphine. Imidazole compounds such as 2-methylimidazole, 2-ethyl-4-methylimidazole and 2-phenylimidazole, 1,8-diaza-bicyclo (5,4,4)
0) tertiary amine compounds such as undecene-7, triethanolamine and benzyldimethylamine, and tetraphenylborate compounds such as tetraphenylphosphonium tetraphenylborate and triphenylphosphine tetraphenylborate. The above curing accelerators may be used alone or in combination of two or more. It should be noted that it is preferable to use, as the curing accelerator to be used, one having relatively little coloring, because the cured resin product has excellent transparency.

In the encapsulating resin of the present invention, if necessary, an inorganic filler, a discoloration preventing agent, an antioxidant, a flame retardant, a coloring agent,
It may also contain modifiers, plasticizers, diluents and the like.
Examples of the inorganic filler include crystalline silica, fused silica, alumina and the like.

It is preferable that the encapsulating resin of the present invention has the above-mentioned contents uniformly mixed. In the case of producing a solid sealing resin at room temperature, for example, a high-speed stirring device such as a homomixer or a three-roll mill is used to heat and knead the mixture, followed by cooling and crushing, and optionally a tablet. It is manufactured by a method such as tableting into a shape. Further, when the liquid sealing resin is produced at room temperature, it is produced by, for example, using a stirrer, mixing while heating if necessary, and then cooling if necessary.

Then, using the sealing resin obtained above, transfer molding or the like is carried out in the case of a solid sealing resin at room temperature, and a casting method or the like is carried out in the case of a liquid sealing resin at room temperature. When a semiconductor chip is sealed by a potting method or the like, an optical semiconductor device having excellent releasability from a mold and excellent transparency and moisture resistance reliability (claim 3 of the present invention is provided.
Optical semiconductor device according to the present invention. The molding method is not particularly limited except that the above sealing resin is used, and a general method can be used.

[0025]

[Examples] (Examples 1 to 6 ) The following three kinds of epoxy resins, a curing agent, a curing accelerator, and three types of release agents were used as raw materials for the sealing resin. -Epoxy resin 1: bisphenol A type epoxy resin [Okaka Shell Epoxy Co., Ltd., trade name 827, epoxy equivalent 185], and-Epoxy resin 2: trifunctional epoxy resin [Mitsui Petrochemical Co., Ltd., trade name VG3101H, epoxy equivalent]. 210]
Epoxy resin 3: trifunctional epoxy resin [manufactured by Nissan Chemical Industries, trade name TEPIC, epoxy equivalent 105], curing agent: hexahydrophthalic anhydride, curing accelerator: methyltriphenylphosphonium bromide Releasing agent 1: a compound (average molecular weight 1400) represented by the above formula (a) and having a weight fraction of the structural portion represented by the above formula (c) of 50% by weight; Agent 2: a compound represented by the above formula (a) and having a weight fraction of the structural portion represented by the above formula (c) of 60% by weight (average molecular weight 1800), and a releasing agent 3: the above A compound represented by the formula (a) and having a weight fraction of the structural portion represented by the formula (c) of 80% by weight (average molecular weight 2400 ).

After blending each of the above-mentioned raw materials in parts by weight shown in Table 1, the mixture was mixed at a temperature of 120 ° C. with a homomixer stirrer.
It was kneaded for a minute, then cooled and then crushed. Then, the crushed product was compressed into tablets to obtain a sealing resin.

Comparative Example 1 A sealing resin was prepared in the same manner as in Example 2 except that montanic acid wax [Wax S, trade name, manufactured by Hoechst Co., Ltd.] (mold release agent 6) was used as the mold release agent. Obtained.

(Comparative Example 2) The same procedure as in Example 2 was repeated except that a compound (release agent 7) having an average molecular weight of 750 and represented by the following formula (d) was used as the release agent. A sealing resin was obtained. The release agent 7 is a compound in which the weight fraction of the structural portion represented by the above formula (c) is 0% by weight.

[0029]

[Chemical 3]

(Comparative Example 3) The release agent has an average molecular weight of 1500 and is represented by the above formula (a), but the weight fraction of the structural portion represented by the above formula (c) is 20% by weight. A sealing resin was obtained in the same manner as in Example 2 except that the compound (release agent 8) in Example 1 was used.

(Comparative Example 4) The release agent has an average molecular weight of 1500 and is represented by the above formula (a), and the weight fraction of the structural portion represented by the above formula (c) is 20% by weight. A sealing resin was obtained in the same manner as in Example 6 except that the compound (release agent 8) was used.

[0032]

[Table 1]

(Evaluation) Using the sealing resins obtained in each of the examples and each of the comparative examples, a sample for evaluation was prepared by the following method, and the light transmittance, white turbidity, releasability, adhesion and moisture resistance were obtained. The reliability was measured by the following method.

The light transmittance was measured by using a transfer molding machine under the conditions of an injection time of 20 seconds, an injection pressure of 7.85 MPa, a mold temperature of 165 ° C., and a cure time of 90 seconds, and an evaluation sample having a thickness of 1 mm was obtained. It was made. Then, the obtained evaluation sample was spectrophotometer (U-3 manufactured by Hitachi, Ltd.).
400) was used to measure the light transmittance at 940 nm.

As for the cloudiness, a sample for evaluation having a thickness of 1 to 8 mm, which was molded in the same manner as the light transmittance, was placed on the line marked with a pencil of B on white paper, and the line was seen through the sample for evaluation of 8 mm. In case of 8 mm, not visible at 8 mm but 5 mm
If a line is visible through the sample for evaluation of △, 5mm
The case where no line was visible through the evaluation sample was marked with x.

The releasability is obtained by mounting a semiconductor chip (4 × 5 mm, aluminum pattern chip, silicon nitride film, 5 μm wiring width) on a lead frame (42 alloy alloy with a part of silver plated). A 16 DPI-type evaluation sample was prepared by molding a structure in which both were connected with a 25 μm gold wire under the same conditions as the light transmittance and sealing. Then, this molding was repeated, and the number of times of continuous molding for smoothly releasing the mold was determined and used as the value of the releasability. In addition, in the case of smoothly releasing the mold even after repeating 100 times, it was marked with ◯.

Regarding moisture resistance reliability, 20 evaluation samples molded for evaluation of mold releasability were taken out, after-cured at 125 ° C. for 12 hours, and then put into a constant temperature and constant humidity chamber of 60 ° C. and 95%. Then, it was taken out every 250 hours, the open short was evaluated, and the processing time at which the cumulative defects exceeded 10% was determined and taken as the value of the moisture resistance reliability. In addition, when it did not reach 10% after 1000 hours of treatment, it was rated as ◯.

(Results) As shown in Table 1, the results of each example are superior in light transmittance and white turbidity as compared with each of the comparative examples, and when the encapsulating resin according to the present invention is used, the transparency is improved. It was confirmed that an excellent resin cured product was obtained. Further, each of the examples has the same or excellent releasability and moisture resistance reliability as compared with each of the comparative examples, and even when repeatedly sealing, the releasability of the mold and the resin cured product is excellent. At the same time, it was confirmed that a cured resin product having excellent moisture resistance reliability was obtained.

[0039]

The encapsulating resin (epoxy resin composition for encapsulating an optical semiconductor) according to the first and second aspects of the present invention contains the compound A as a release agent, and therefore encapsulation is repeated. Even in such a case, a resin cured product having excellent releasability between the mold and the resin cured product and having excellent transparency and moisture resistance reliability can be obtained.

An optical semiconductor device according to claim 3 of the present invention is
Since the encapsulating resin according to claim 1 or 2 of the present invention is used, the optical semiconductor device is excellent in mold releasability from the mold, and excellent in transparency and moisture resistance reliability.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-9-208805 (JP, A) JP-A-3-287641 (JP, A) JP-A-11-302499 (JP, A) JP-A-11- 43493 (JP, A) JP 9-176373 (JP, A) JP 1-215905 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08L 63/00-63 / 10 C08K 5/521 C08L 71/02-71/03 H01L 23/29

Claims (3)

(57) [Claims] 1. An epoxy resin composition for optical-semiconductor encapsulation containing an epoxy resin, a curing agent, a curing accelerator and a release agent, which is represented by the following formula (a ) as a release agent, and:
The weight fraction of the structural portion represented by the following formula (c) is 40 to 9
An epoxy resin composition for encapsulating an optical semiconductor, comprising 0% by weight of a compound. [Chemical 1] 2. The epoxy resin composition for optical-semiconductor encapsulation according to claim 1, wherein the compound represented by the formula (a ) has an average molecular weight of 500 to 3,000. 3. An optical semiconductor device obtained by encapsulating a semiconductor chip using the epoxy resin composition for encapsulating an optical semiconductor according to claim 1.