JP7465703B2 - Resin molding for sealing optical semiconductors and method for producing same - Google Patents

Description

The present invention relates to a resin molded product for sealing optical semiconductors and a method for producing the same.

Optical semiconductor elements are sealed in ceramic or plastic packages and assembled into devices. However, ceramic packages are mainly used because the constituent materials are relatively expensive and are not suitable for mass production. Among these, the technology of transfer molding an epoxy resin composition that has been compressed into tablets in advance has become mainstream in terms of workability, mass production, and reliability.

However, in epoxy resin compositions for sealing optical semiconductors used in plastic packages, the individual components of the epoxy resin, curing agent, and curing accelerator are relatively difficult to disperse, and it is not easy to mix and disperse them uniformly as a whole, which causes the problem that the curing reaction is non-uniform and molding irregularities and molding voids are likely to occur. These irregularities and voids cause optical irregularities, which impair the reliability of the optical semiconductor device.

To solve these problems, Patent Document 1 discloses a technique in which an epoxy resin composition is very finely ground and then tableted, thereby ensuring uniform dispersion of the composition, reducing molding irregularities and molding voids, and eliminating optical irregularities. Furthermore, Patent Document 2 discloses a technique in which an epoxy resin composition is granulated into granules and tableted.

Japanese Patent Application Laid-Open No. 3-3258 JP 2011-9394 A

The present invention aims to provide a resin molded product for sealing optical semiconductors that has a wide production margin and can be stably transferred molded in optical semiconductor production, as well as a manufacturing method thereof.

The present invention relates to a resin molded product for sealing optical semiconductors, which contains a resin having a molecular weight distribution Mw/Mn, which is the ratio of weight average molecular weight Mw to number average molecular weight Mn, of 2.7 or less.

It is preferable that the weight average molecular weight Mw of the resin is 3000 to 7000, and the number average molecular weight Mn is 1500 to 2600.

The present invention also relates to a resin molded product for encapsulating optical semiconductors, which has a minimum melt viscosity of 300 dPa·s or less, measured in accordance with EMMI (Epoxy Molding Materials Institute) standard 1-66 under conditions of a mold temperature of 150°C, a molding pressure of 970 kgf/ ^cm2 , a curing time of 120 s, and an injection speed of 2.0 cm/s, and has a ratio b/a of 20 or more, where b is the value obtained by subtracting the minimum melt viscosity from the index viscosity of 800 dPa·s, and a is the time a required for the melt viscosity to reach 800 dPa·s again during the curing process after passing through the minimum melt viscosity.

The resin tablet for sealing optical semiconductors preferably contains a reaction product of a thermosetting resin and a curing agent, and a curing accelerator.

The present invention also relates to an optical semiconductor encapsulant obtained by molding the optical semiconductor encapsulating resin molded product, and
The present invention relates to an optical semiconductor device including an optical semiconductor element and the optical semiconductor encapsulant that encapsulates the optical semiconductor element.

Furthermore, the present invention relates to a method for producing the resin molded product for sealing optical semiconductors, which comprises the steps of kneading a thermosetting resin, a curing agent, and a curing accelerator to obtain a curable resin composition, heat-treating the curable resin composition, granulating the curable resin composition to obtain a granular curable resin composition, and molding the granular curable resin composition.

The resin molded product for sealing optical semiconductors of the present invention contains a resin with a narrow molecular weight distribution, and the time it takes to harden after reaching the minimum melt viscosity during optical semiconductor production is short, so the production margin in optical semiconductor production is wide and stable transfer molding can be performed.

The resin molded product for sealing optical semiconductors of the present invention is characterized by containing a resin having a molecular weight distribution Mw/Mn, which is the ratio of weight average molecular weight Mw to number average molecular weight Mn, of 2.7 or less. Examples of the resin molded product for sealing optical semiconductors include tablets and sheets, and are members that are formed to cover the optical semiconductor element that constitutes the optical semiconductor device and seal the element.

The molecular weight distribution can be calculated from the weight average molecular weight Mw and number average molecular weight Mn measured by dissolving the resin components contained in the molded product in an organic solvent and using gel permeation chromatography (GPC). The molecular weight distribution Mw/Mn is 2.7 or less, preferably 2.3 or less, and more preferably 2.0 or less. If it exceeds 2.7, stable transfer molding may not be possible.

The weight average molecular weight Mw is preferably 3000 to 7000. The number average molecular weight Mn is preferably 1500 to 2600. If Mw is less than 3000 or Mn is less than 1500, the resin will have too high fluidity during molding, and will tend to leak out of the product, causing burrs and impairing the appearance. If Mw exceeds 7000 or Mn exceeds 2600, the resin will have low fluidity during molding, and will tend to result in poor filling of the product.

When the optical semiconductor encapsulating resin molded article is a tablet, its volume is not particularly limited, but is preferably 1 to ¹⁰⁰ cm3, and more preferably 10 to 100 ^cm3 . If the volume is too small, it tends to be difficult to see the difference in the variation in the reaction state.

The resin molded product for encapsulating optical semiconductors of the present invention is characterized in that it has a minimum melt viscosity of 300 dPa·s or less, measured in accordance with EMMI (Epoxy Molding Materials Institute) standard 1-66 under conditions of a mold temperature of 150°C, a molding pressure of 970 kgf/ ^cm2 , a curing time of 120 s, and an injection speed of 2.0 cm/s, and that the ratio b/a of the value b obtained by subtracting the minimum melt viscosity from the index viscosity of 800 dPa·s to the time a required for the melt viscosity to reach 800 dPa·s again during the curing process after the minimum melt viscosity is 20 or more.

The minimum melt viscosity is 300 dPa·s or less, preferably 200 dPa·s or less. If it exceeds 300 dPa·s, there is a tendency for poor filling into the product during molding. There is no particular lower limit, but 30 dPa·s or more is preferred, 50 dPa·s or more is more preferred, and 80 dPa·s or more is even more preferred.

The value b obtained by subtracting the minimum melt viscosity from the index viscosity of 800 dPa·s is not particularly limited, but is preferably 500 to 770, more preferably 500 to 750, and even more preferably 500 to 720. In addition, the value b obtained by subtracting the minimum melt viscosity from the index viscosity of 800 dPa·s and the time a required for the viscosity to reach 800 dPa·s again during the curing process after passing the minimum melt viscosity are not particularly limited, but are preferably 5 to 32, and more preferably 10 to 30.

The ratio b/a of the time it takes for the melt viscosity to reach 800 dPa·s again during the curing process after passing the minimum melt viscosity is 20 or more, preferably 22 or more, and more preferably 25 or more. If it is less than 20, it will take too long to cure, the molding cycle will be long, and a high cycle will not be achieved.

The measuring device used to measure melt viscosity here consists of a barrel in which the sample is filled, a mold with a spiral-shaped cavity, and a mold into which the sample is pressed. The entire device is heated to the measurement temperature, and the resin composition is poured into the barrel. After a certain period of time has passed, the plunger is pressed in to press. This device can be used to measure melt viscosity, etc. The measuring device conforms to EMMI (Epoxy Molding Materials Institute) standard 1-66.

The ratio b/a of the molecular weight distribution Mw/Mn, the minimum melt viscosity, the value b obtained by subtracting the minimum melt viscosity from the index viscosity of 800 dPa·s, and the time a required for the viscosity to reach 800 dPa·s again during the curing process after passing through the minimum melt viscosity can be adjusted by controlling the reaction during kneading of the curing components and the curing agent. The reaction can be controlled, for example, by appropriately adjusting the type and amount of the thermosetting resin, the type and amount of the curing agent, the type and amount of the curing accelerator, the reaction temperature, the reaction time, the resin shape, etc.

The resin molded product for sealing optical semiconductors of the present invention preferably contains a reaction product of a thermosetting resin and a curing agent in addition to a thermosetting resin, a curing agent, and a curing accelerator. Fillers such as silica powder can be added to the extent that they do not impair light transmission.

Thermosetting resins include epoxy resins, silicone resins, and hybrid resins of epoxy resins/silicone resins. Of these, epoxy resins are preferred.

As the epoxy resin, one with little coloring is preferred, and examples thereof include bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, alicyclic epoxy resin, heterocyclic epoxy resin such as triglycidyl isocyanate and hydantoin epoxy, water-added bisphenol A type epoxy resin, aliphatic epoxy resin, glycidyl ether type epoxy resin, etc. These can be used alone or in combination of two or more kinds.

As a curing agent, an acid anhydride that causes little coloring in the cured product of the resin composition during or after curing is suitable. Examples include phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methylnadic anhydride, nadic anhydride, and glutaric anhydride. Other curing agents include amine-based curing agents such as metaphenylenediamine, dimethyldiphenylmethane, diaminodiphenylsulfone, m-xylylenediamine, tetraethylenepentamine, diethylamine, and propylamine, as well as phenolic resin-based curing agents. These may be used alone or in combination of two or more.

The amount of hardener to be used is not particularly limited, but is preferably 20 to 80 parts by weight, more preferably 40 to 60 parts by weight, per 100 parts by weight of epoxy resin. If the amount is less than 20 parts by weight, the hardening speed will be slow, and if the amount is more than 80 parts by weight, there is an excess amount for the hardening reaction, which may cause a deterioration in various physical properties.

Examples of the curing accelerator include tertiary amines such as triethanolamine, imidazoles such as 2-methylimidazole, organic phosphorus compounds such as tetraphenylphosphonium tetraphenylborate and triphenylphosphine, and diazabicycloalkene compounds such as 1,8-diazabicyclo[5,4,0]undecene-7 and 1,5-diazabicyclo[4,3,0]nonene-5. These may be used alone or in combination of two or more.

The amount of the curing accelerator is not particularly limited, but can be appropriately selected from the range of, for example, 0.1 to 5 parts by mass per 100 parts by mass of epoxy resin, with 0.5 to 3 parts by mass being preferred, and 1 to 2 parts by mass being more preferred. If the amount of the curing accelerator is too small, the curing speed will be slow and productivity will decrease, while if the amount of the curing accelerator is too large, the curing reaction will be too fast, making it difficult to control the reaction state and causing reaction variation.

In addition to the above-mentioned components, additives such as color inhibitors, lubricants, modifiers, deterioration inhibitors, and mold release agents may be used as necessary in the optical semiconductor encapsulation resin composition of the present invention.

Examples of color inhibitors include phenolic compounds, amine compounds, organic sulfur compounds, and phosphine compounds.

Lubricants include waxes such as stearic acid, magnesium stearate, and calcium stearate, as well as talc. When the above lubricants are added, the amount of the lubricants added is appropriately set according to the tableting conditions, but it is preferable to set the amount to 0.1 to 0.4% by mass of the entire resin composition.

The method for producing a resin molded article for encapsulating an optical semiconductor of the present invention includes the steps of kneading a thermosetting resin, a curing agent, and a curing accelerator to obtain a curable resin composition;
heat-treating the curable resin composition;
granulating the curable resin composition to obtain a granular curable resin composition;
and a step of molding the granular curable resin composition.

The kneading method is not particularly limited, but examples include a method using an extruder. The kneading temperature is also not particularly limited and can be changed appropriately depending on the characteristics of the thermosetting resin. It is also possible to set the temperature high so as to promote the reaction during kneading. Specifically, 80 to 150°C is preferable, and 110 to 130°C is more preferable.

The shape of the curable resin composition obtained by kneading is not particularly limited, and examples include film, sheet, granules, and lumps.

The thickness of the curable resin composition obtained by kneading is not particularly limited, but is preferably 1 to 30 mm, and more preferably 2 to 20 mm. If the thickness is less than 1 mm, the composition is thin and susceptible to moisture absorption, and if the thickness exceeds 30 mm, it takes time to cool and the reaction tends to vary due to internal heat accumulation.

The curable resin composition obtained by kneading is heat-treated to obtain a B-stage (semi-cured) resin composition for sealing optical semiconductors. The heat treatment temperature is not particularly limited, but is preferably 25 to 100°C, and more preferably 60 to 80°C. If the temperature is less than 25°C, the curing reaction tends to be slow and productivity tends to decrease, and if the temperature exceeds 100°C, the curing reaction tends to be fast and it tends to be difficult to terminate the reaction at the specified reaction state. The heat treatment time is not particularly limited, and can be changed as appropriate depending on the characteristics of the thermosetting resin.

The heat-treated resin composition is granulated to obtain a granular resin composition. Before granulation, the resin composition can be pulverized using a ball mill, turbo mill, or the like. The granulation method is not particularly limited, but examples include a method using a dry compression granulator. The average particle size of the granules obtained by granulation is not particularly limited, but is preferably 1 to 5000 μm, and more preferably 100 to 2000 μm. If it exceeds 5000 μm, the compression ratio tends to decrease.

The obtained granular resin composition is molded to obtain a molded product. Examples of molded products include tablets and sheets, and molding methods include tableting to obtain tablets and extrusion to obtain sheets. The obtained molded products are not only free of chipping, cracking, and weight variations, but also, as mentioned above, have a small molecular weight distribution Mw/Mn and minimum melt viscosity, and the ratio b/a of the value b obtained by subtracting the minimum melt viscosity from the index viscosity of 800 dPa·s to the time a until the melt viscosity reaches 800 dPa·s again during the curing process after the minimum melt viscosity is large at 20 or more, resulting in a high-quality molded product that can be stably transferred molded.

When the molded product is a tablet, the conditions for tablet compression are adjusted as appropriate depending on the composition, average particle size, particle size distribution, etc. of the granular curable resin composition, but in general, it is preferable to set the compression ratio during tablet compression to 90-96%. That is, if the compression ratio value is less than 90%, the density of the tablet may be low and it may be prone to cracking, and conversely, if the compression ratio value is more than 96%, cracks may occur during tablet compression, causing chipping or breakage when released from the mold.

The molded product is used to encapsulate the optical semiconductor element by transfer molding to produce an optical semiconductor device. The molecular weight distribution of the resin contained in the molded product is narrow, and the time it takes to harden after reaching the minimum melt viscosity during optical semiconductor production is short, resulting in a highly reliable, high-quality optical semiconductor element without optical unevenness. Therefore, when this optical semiconductor device is operated to obtain an image, there is no striped pattern caused by optical unevenness, and it has the advantage of providing a clear image.

In addition, since the resin molded product for sealing optical semiconductors of the present invention is used for resin sealing of optical semiconductor elements such as light receiving elements, it is preferable that it is transparent from an optical viewpoint. In this case, "transparent" means that the cured product of the curable resin composition constituting the tablet has a transmittance of 98% or more at 400 nm.

Next, examples will be described together with comparative examples. However, the present invention is not limited to the following examples.

The materials used are shown below.
Epoxy resin 1: Bisphenol type epoxy resin A (epoxy equivalent 650)
Epoxy resin 2: Triglycidyl isocyanurate (epoxy equivalent: 100)
Hardener: Tetrahydrophthalic anhydride (acid anhydride equivalent: 152)
Curing accelerator: 2-ethyl-4-methylimidazole

Examples 1 to 3 and Comparative Example 1
The raw materials were mixed in the amounts shown in Table 1 by heating and dissolving them in an extruder set at the temperature shown in Table 1, and the resin coming out of the extruder outlet was molded into a thickness of 2 to 10 mm and heat-treated at 60°C for 60 minutes. The residence time in the extruder was about 2 minutes. The obtained epoxy resin composition was granulated and sized using a roll granulator (manufactured by Nippon Granulator Co., Ltd., test machine: Model 1531) to obtain an epoxy resin composition for sealing optical semiconductors. The obtained resin composition for sealing optical semiconductors was tableted using a No. 20 rotary tablet press to produce resin tablets for sealing optical semiconductors shown in Table 1. The compression ratio was 90 to 93%.

The tablets prepared in each example were used to evaluate the molecular weight and viscosity characteristics using the methods described below. The evaluation results are shown in Table 1.

<Molecular weight>
A part of the obtained tablet was dissolved in tetrahydrofuran and measured under the following conditions using a GPC apparatus (HLC-8320GPC, manufactured by Tosoh Corporation) to determine the number average molecular weight Mn and weight average molecular weight Mw in terms of polystyrene.
Column: TSKgel Super HZMH/HZ4000/HZ3000/HZ2000
Column size: 6.0 mm I.D. x 150 mm
Eluent: THF
Flow rate: 0.6 mL/min
Detector: RI
Column temperature: 40°C
Injection volume: 20 μL

<Viscosity characteristics>
The measurement was performed according to EMMI (Epoxy Molding Materials Institute) standard 1-66, under the conditions of a mold temperature of 150°C, molding pressure of 970 kgf/cm ² , curing time of 120 s, and injection speed of 2.0 cm/s. Specifically, using a flowability measuring device, the obtained tablet was coarsely crushed and the powder passed through a sieve with an opening diameter of 5 mm was placed in a pod maintained at 150°C, and pressed by pushing the plunger at a constant speed. The melt viscosity calculated from the measured torque was plotted against time, and the value b obtained by subtracting the minimum melt viscosity from the index viscosity of 800 dPa·s and the time a until the minimum melt viscosity was reached again in the curing process were obtained.

From the experimental results shown in Table 1, the molded bodies of Examples 1 to 3 had small resin molecular weight distributions Mw/Mn, minimum melt viscosities of 300 dPa·s or less, and tablets were obtained in which the ratio b/a (value b obtained by subtracting the minimum melt viscosity from the index viscosity of 800 dPa·s, to the time a required for the viscosity to reach 800 dPa·s again during the curing process after the minimum melt viscosity) was 20 or more. Therefore, the production margin in optical semiconductor production is wide, and stable transfer molding is possible.
On the other hand, in Comparative Example 1, the molecular weight distribution Mw/Mn of the resin was as high as 2.9, and only tablets with a small b/a of 18.8 were obtained. Therefore, the production margin in the production of optical semiconductors is narrow, and it is difficult to perform stable transfer molding.

The present invention relates to an optical semiconductor encapsulation resin molded product used for encapsulating an optical semiconductor element, and a manufacturing method thereof, and can be used in the manufacture of an optical semiconductor device.

Claims (5)

The minimum melt viscosity, measured according to EMMI (Epoxy Molding Materials Institute) standard 1-66 under conditions of a mold temperature of 150°C, a molding pressure of 970 kgf/cm ² , a curing time of 120 seconds, and an injection speed of 2.0 cm/s, is 300 dPa·s or less;
A resin molded product for sealing optical semiconductors, in which the ratio b/a of the value b obtained by subtracting the minimum melt viscosity from the index viscosity of 800 dPa·s to the time a required for the melt viscosity to reach 800 dPa·s again during the curing process after passing through the minimum melt viscosity is 20 or more. 2. The resin molding for sealing an optical semiconductor according to claim 1, further comprising a reaction product of a thermosetting resin and a curing agent, and a curing accelerator. 3. An optical semiconductor encapsulant obtained by molding the optical semiconductor encapsulating resin molded product according to claim 1 or 2 . An optical semiconductor device comprising: an optical semiconductor element; and the optical semiconductor encapsulant according to claim 3 for encapsulating the optical semiconductor element. A step of kneading a thermosetting resin, a curing agent, and a curing accelerator to obtain a curable resin composition;
heat-treating the curable resin composition;
granulating the curable resin composition to obtain a granular curable resin composition;
3. The method for producing a molded resin product for encapsulating an optical semiconductor according to claim 1, further comprising the step of molding the granular curable resin composition.