Yazaki Corporation

Douglas Meyers

Satyabrata Raychaudhuri

Yongan Yan

Fikret Nuri Kirkbir

D Laurence Meixner

Mark Morris

Rahul Ganguli

Hideaki Murata

An encapsulant is described for an optoelectronic device or optical component, which provides a coefficient of thermal expansion of less than 50 ppm/&#xb0; C., with a variation of less than &#xb1;30%, and further provides an optical transmittance of at least 20% at a wavelength in the range of 400 to 900 nm, at an encapsulant thickness of about 1 mm. The encapsulant includes a filler consisting essentially of glass particles having diameters smaller than 500 &#x3bc;m, being essentially free of titania and lead oxide, and having a refractive index in the range of 1.48 to 1.60, with a variance of less than about 0.001. A method for making the encapsulant also is described, the method including steps of (1) processing the glass to form particles having diameters between 1 and 500 &#x3bc;m, (2) preparing an epoxy resin composition having at a cured stage a refractive index close to that of the glass filler particles, (3) mixing the epoxy resin composition with the filler particles to form a filled epoxy resin composition, (4) encapsulating an optoelectronic device with the filled epoxy resin composition, and (5) curing the filled epoxy resin composition.

Method for making filled epoxy resin compositions

Filled epoxy resin compositions

An encapsulant for use with opto-electronic devices and optical components incorporates a filler made from a glass that has been processed into particle form and heated to a predetermined temperature for a predetermined time, along with an epoxy having an index of refraction matched to that of the glass and heated to a predetermined temperature for a predetermined time, to prevent settling of the filler particles after mixing the filler particles with the epoxy, and thereby obtaining uniform dispersion of the particles within the epoxy. The encapsulant provides for high light transmittance, and its coefficient of thermal expansion can be varied by varying the amount of filler without substantially altering the optical properties of the encapsulant. The coefficient of thermal expansion variation within the encapsulant preferably is less than 30%, due to uniform dispersion of the filler particles within the epoxy.

Process for making encapsulant for opto-electronic devices

Encapsulant for opto-electronic devices and method for making it

A sol-gel process for producing dry porous gel monoliths, e.g., silica glass monoliths, in which the successive process steps of gelling, aging and drying all occur within a mold formed of a selected porous material, e.g., graphite. The mold is inert to the gel solution and it has sufficient strength to withstand the temperatures and pressures encountered during the process. The mold and gel thereby can remain within a sealed autoclave during these process steps, and mechanical handling of the mold and the gel are minimized. This substantially enhances the process' efficiency. Alternatively, the mold can have a non-porous inner skin to enhance ease of cleaning of the mold, and of removal of the gel.

Sol-gel process using porous mold

A sol-gel process for producing dry porous gel monoliths, e.g., silica glass monoliths, in which the successive process steps of gelling, aging and drying all occur within a mold formed of a porous material, e.g., graphite. The mold is inert to the gel solution and it has sufficient strength to withstand the temperatures and pressures encountered during the process, yet it has sufficient porosity to facilitate the escape of liquid from the gel pores directly through the mold, itself. The mold and gel thereby can remain within a sealed autoclave during these process steps, and mechanical handling of the mold and the gel are minimized. This substantially enhances the process' efficiency. Alternatively, the mold can have a non-porous inner skin.

An improved apparatus, and related method of operation, is described for rapidly drying large monoliths of glass, ceramic and/or composite material, under subcritical conditions, while minimizing the risk of cracking the monolith during the drying process. The apparatus incorporates a pressure chamber for carrying the monolith to be dried, with no significant limitation on the size of the monolith relative to the size of the chamber. The monolith is initially immersed in a suitable drying solvent, and the temperature of the pressure chamber is raised to a predetermined value below the solvent's critical temperature, which raises the pressure to a predetermined value, likewise below the solvent's critical pressure. At a selected time during the drying process the pressure chamber is connected to a diffusion chamber, to draw away and condense solvent vapor. This drawing away of solvent vapor continues until the monolith is dry, at which time the pressure chamber is purged with an inert gas and then depressurized in a controlled manner. The apparatus thereby is configured to dry the monolith at an even lower subcritical pressure than previous apparatus of this kind, leading to increased safety and reduced operating expenses.

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Calabasas, CA, United States of America

Douglas Meyers