HK1183160B

HK1183160B - Light emitting diode assembly and thermal control blanket and methods relating thereto

Info

Publication number: HK1183160B
Application number: HK13110303.6A
Authority: HK
Inventors: C．D．西蒙尼; T．E．卡内
Original assignee: Dupont Electronics, Inc.
Priority date: 2010-08-18
Filing date: 2011-06-01
Publication date: 2018-02-09

Description

Light emitting diode assemblies and thermal control blankets and methods relating thereto

Technical Field

The field of the disclosure is reflective materials for light emitting diode assemblies and thermal control blankets.

Background

Broadly speaking, reflective materials for use in lighting systems are known; see, for example, published U.S. patent application 2009-. Such reflective materials are typically used to enhance and redirect light in a desired direction. Conventional reflective surfaces include metallic coatings, white pigmented polyethylene terephthalate and white pigmented polyamide. Conventional reflective surfaces can present problems for any of a number of reasons, such as:

i. insufficient whiteness, ii. insufficient reflectance, iii. poor reflectance and poor color stability after a period of heat exposure (i.e. poor heat aging), iv. poor mechanical properties, color stability with time difference of v.uv exposure (i.e. poor UV aging), and vi. distortion and discoloration during welding. There is therefore a need for improved reflective materials for lighting system components.

Drawings

The drawings illustrate the invention by way of example and are not intended to limit the invention.

FIG. 1 is an unfilled polyimide film of the present disclosure andgraph of percent transmission of film.

FIG. 2 is a graph of color L change versus hours of exposure to 130 deg.C for various reflective films.

FIG. 3 is a graph of percent change in reflectance at 550nm versus hours of exposure to 130 ℃ for various reflective films.

Disclosure of Invention

One embodiment of the present disclosure is a light emitting diode assembly. The light emitting diode assembly includes:

A. a filled polyimide layer having a filled polyimide layer first surface and a filled polyimide layer second surface. The filled polyimide layer consists essentially of:

i) a polyimide in an amount of 50 to 75 weight percent of the filled polyimide layer, the polyimide derived from:

a. at least 45 mole%, based on the total dianhydride content of the polyimide, of 3,3',4,4' -biphenyltetracarboxylic dianhydride, and

b. at least 50 mole percent 2,2' -bis (trifluoromethyl) benzidine, based on the total diamine content of the polyimide;

a white pigment particulate filler having an average particle size of less than 1.9 microns and a content of 20 to 50 weight percent of the filled polyimide layer;

B. conductive traces formed on at least the filled polyimide layer first surface;

C. at least one light emitting diode connected to the filled polyimide layer first surface or to the conductive trace; and

D. an encapsulant covering the exposed surface of the light emitting diode and the at least partially filled polyimide layer first surface.

Another embodiment of the present disclosure is a thermal control blanket comprising a filled polyimide layer. The filled polyimide layer consists essentially of:

A. a polyimide in an amount of 50 to 75 weight percent of the filled polyimide layer, the polyimide derived from:

a) at least 45 mole%, based on the total dianhydride content of the polyimide, of 3,3',4,4' -biphenyltetracarboxylic dianhydride,

b) at least 50 mole percent 2,2' -bis (trifluoromethyl) benzidine, based on the total diamine content of the polyimide; and

B. a white pigment particulate filler in an amount of 20 to 50 weight percent of the filled polyimide layer and having an average particle size of less than 1.5 microns;

C. a conductive filler in an amount up to 5 weight percent of the filled polyimide layer. The thermal control blanket has a color L value (as determined by ASTM E308[10 ° observer and illuminant D65 ]) of at least 85 and a reflectance (as determined by ASTM E1164) of at least 80%.

Detailed Description

Definition of

As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having" or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a method, process, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such method, process, article, or apparatus. Further, unless specifically stated otherwise, "or" means an inclusive or, and not an exclusive or. For example, any one of the following satisfies condition a or B: a is true (or present) and B is false (or not present), a is false (or not present) and B is true (or present), and both a and B are true (or present).

In addition, "a" or "an" is used to describe elements and components of the invention. This is done merely for convenience and to give a general sense of the invention. This description should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise.

As used herein, the term "dianhydride" is intended to include precursors, derivatives or their analogs, which may not strictly be dianhydrides but may still react with diamines to form polyamic acids, which may in turn be converted to polyimides.

As used herein, the term "diamine" is intended to include precursors, derivatives or their analogs, which may not be, strictly speaking, a diamine but which can still react with a dianhydride to form a polyamic acid which can then be converted to a polyimide.

As used herein, the term "polyamic acid" is intended to include any polyimide precursor material derived from a combination of a dianhydride and a diamine or capable of being converted to a polyimide.

As used herein, the term "chemical conversion" or "chemically converted" means the conversion of a polyamic acid to a polyimide using a catalyst, a dehydrating agent, or both, and is intended to include a partially chemically converted polyimide that is subsequently dried at elevated temperatures to a solids content of greater than 98%.

As used herein, the term "conversion chemical" refers to a catalyst, a dehydrating agent, or both, that converts polyamic acid to polyimide.

As used herein, the term "finishing solution" refers to a dianhydride in a polar aprotic solvent that is added to a low molecular weight polyamic acid solution having an amine chain end to increase the molecular weight and viscosity of the polyamic acid solution. The dianhydride used is typically, but not necessarily, the same dianhydride (or one of them when more than one dianhydride is used) used to prepare the polyamic acid.

As used herein, the term "panel" means a filled polyimide layer that has been cut to a desired size.

As used herein, the term "prepolymer" is intended to mean a relatively low molecular weight polyamic acid solution having a concentration ranging between 15-25 weight percent, prepared by using a stoichiometric excess of diamine to give a solution viscosity of about 50-100 poise.

When an amount, concentration, or other value or parameter is given as either a range, preferred range, or a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions within the range.

In describing certain polymers, it should be understood that sometimes applicants refer to polymers by the monomers used to make them or the amounts of the monomers used to make them. Although such descriptions may not include the specific nomenclature used to describe the final polymer or may not contain terms that define the article by way, any such reference to monomers and amounts should be construed to mean that the polymer is made from those monomers, unless the context indicates or implies otherwise.

The materials, methods, and examples herein are illustrative only and are not intended to be limiting unless specifically indicated. Although methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, suitable methods and materials are described herein.

In some embodiments, the present disclosure relates to a light emitting diode assembly and a thermal control blanket, both having a filled polyimide layer. The filled polyimide layer comprises a light colored polyimide. Typically the polyimide has a certain color ranging from yellow to orange/brown. An advantage of the polyimides of the present disclosure is that when the white pigment particulate fillers of the present disclosure are added to the polyimides, the resulting films are more true to the color of the pigment. Thus, the filled polyimide film of the present disclosure can be used as a reflective surface with high temperature exposure. The filled polyimide layer i.shows sufficient whiteness, ii.shows sufficient reflectivity, iii. retains reflectivity and retains color after a period of heat exposure (i.e. good heat aging), iv. has sufficient mechanical properties, and v. does not deform or discolor during soldering.

Polyimide, polyimide resin composition and polyimide resin composition

The polyimides of the present disclosure have advantages over other polymers. The polyimide is an aromatic polyimide with high temperature stability and can withstand processing temperatures that are typically too high for many other polymers. The polyimides of the present disclosure have advantages over other aromatic polyimides. The polyimide of the present disclosure exhibits a light color and is transparent. Thus, after the pigment is added, the color is more true of the color of the pigment. For the purposes of this disclosure, light is intended to mean greater than 80% of the light transmitted at wavelengths of 400 to 700nm as measured using an Agilent8453UV/Vis spectrophotometer.

The polyimide is present in an amount between and including any two of the following values: 50,55,60,65,70 and 75 wt% of a filled polyimide layer. In some embodiments, the polyimide is present in an amount of 50 to 75 weight percent of the filled polyimide layer.

The polyimides of the present disclosure have at least 45 mole% of 3,3',4,4' -biphenyltetracarboxylic dianhydride (BPDA) based on the total dianhydride content of the polyimide and at least 50 mole% of 2,2' -bis (trifluoromethyl) benzidine (TFMB) based on the total diamine content of the polyimide. In some embodiments, the polyimide is derived from at least 50 mole% of 3,3',4,4' -biphenyltetracarboxylic dianhydride, based on the total dianhydride content of the polyimide.

In some embodiments, the polyimides of the present disclosure have at least 50 mole% of 3,3',4,4' -biphenyltetracarboxylic dianhydride (BPDA) based on the total dianhydride content of the polyimide and at least 50 mole% of 2,2' -bis (trifluoromethyl) benzidine (TFMB) based on the total diamine content of the polyimide.

In some embodiments, the BPDA monomer may be used alone (i.e., 100 mole% of the total dianhydride component) or may be used in combination with one or more other dianhydrides from a selected group disclosed herein. In some embodiments, the additional dianhydrides, alone or in combination with each other, may constitute no more than 55 mole percent of the total dianhydride content. In some embodiments, the additional dianhydride may constitute no more than 50 mole percent of the total dianhydride content.

In some embodiments, the polyimide is additionally derived from not more than 55 weight percent pyromellitic dianhydride, based on the total dianhydride content of the polyimide. In another other embodiment, the polyimide is additionally derived from not more than 55 weight percent 4,4' -oxydiphthalic anhydride (ODPA) based on the total dianhydride content of the polyimide; 4,4'- (4,4' -isopropylidenediphenoxy) bis (phthalic anhydride) (BPADA); 2,3,3',4' -biphenyltetracarboxylic dianhydride; 2,2',3,3' -biphenyltetracarboxylic dianhydride or a mixture thereof. In another embodiment, the polyimide is additionally derived from not more than 55 weight percent of 4,4' - (hexafluoroisopropylidene) phthalic anhydride (6 FDA). In another embodiment, the polyimide is additionally derived from not more than 55 weight percent of diphenyl sulfone tetracarboxylic dianhydride (DSDA), based on the total dianhydride content of the polyimide; 4,4' -bisphenol a dianhydride; 1,2,3, 4-cyclobutanetetracarboxylic dianhydride; (-) - [1S, 5R, 6S ] -3-oxabicyclo [3.2.1] octane-2, 4-dione-6-spiro-3- (tetrahydrofuran-2, 5-dione); bicyclo [2.2.2] oct-7-ene-2, 3,5, 6-tetracarboxylic acid dianhydride; 9, 9-disubstituted xanthenes or mixtures thereof.

In some embodiments, the TFMB diamine monomer may be used alone (i.e., 100 mole percent of the total diamine content) or in combination with one or more other diamines from a selected group disclosed herein. These additional diamines, used alone or in combination with one another, may constitute no more than 50 mole% of the total diamine content. In some embodiments, the polyimide is additionally derived from no more than 50 mole percent of trans-1, 4-diaminocyclohexane 3, 5-diaminobenzotrifluoride, based on the total diamine content of the polyimide; 2- (trifluoromethyl) -1, 4-phenylenediamine; 1, 3-diamino-2, 4,5, 6-tetrafluorobenzene; 2, 2-bis (3-aminophenyl) 1,1,1,3,3, 3-hexafluoropropane; 2,2' -bis- (4-aminophenyl) -hexafluoropropane (6F diamine); 3,4' -diaminodiphenyl ether (3,4' -ODA), m-phenylenediamine (MPD), 4, 4-bis (trifluoromethoxy) benzidine, 3,3' -diamino-5, 5' -trifluoromethylbiphenyl, 3,3' -diamino-6, 6' -trifluoromethylbiphenyl, 3,3' -bis (trifluoromethyl) benzidine; 2, 2-bis [4- (4-aminophenoxy) phenyl ] hexafluoropropane (4-BDAF),4,4 '-diaminodiphenyl sulfide (4,4' -DDS); 3,3 '-diaminodiphenyl sulfone (3,3' -DDS); 4,4' -diaminodiphenyl sulfone; 2,2' -bis (dimethyl) benzidine; 3,3' -bis (dimethyl) benzidine; 4,4 '-trifluoromethyl-2, 2' -diaminobiphenyl or mixtures thereof.

In some embodiments, the polyimide is additionally derived from no more than 50 mole percent; diamino cyclooctane; tetramethylenediamine hexamethylenediamine; octamethylenediamine; dodecamethylenediamine; aminomethyl-cyclooctylmethylamine; aminomethyl cyclododecylmethylamine; aminomethyl cyclohexylmethylamine, or mixtures thereof.

In some embodiments, the polyimide is derived from 90 mole% 3,3',4,4' -biphenyltetracarboxylic dianhydride (BPDA) and 100 mole% 2,2' -bis (trifluoromethyl) benzidine (TFMB). In some embodiments, the BPDA// TFMB polyimide is finished using a PMDA solution (finishing solution). In some embodiments, the polyimide is derived from 100 mole% 3,3',4,4' -biphenyltetracarboxylic dianhydride (BPDA) and 100 mole% 2,2' -bis (trifluoromethyl) benzidine (TFMB). In some embodiments, the BPDA// TFMB polyimide is finished using a BPDA solution (finishing solution).

The polyimides, which are aromatic, have mechanical properties that are generally superior to those of films made with semi-aromatic polymers. Semi-aromatic polymers for the purposes of this disclosure are intended to mean polycondensates in which 100 mol% of only one of the monomer units is aliphatic. For example, 100 mole% of the glycol or 100 mole% of the dicarboxylic acid (ester) forming the polyester is aliphatic (e.g., polyethylene terephthalate (PET)); alternatively, 100 mole% of the dicarboxylic acids or 100 mole of the diamines forming the polyamide are aliphatic. An aromatic polymer is a polymer in which at least 50% of each monomer unit is aromatic. For example, at least 50 mole% of the diols and 50 mole of the dicarboxylic acids (esters) forming the polyester are aromatic. In some embodiments, the advantage of aromatic polymers over semi-aromatic polymers is that aromatic polymers tend to have a high Tg, high thermal stability and in many cases improved mechanical properties such as modulus, tensile strength and elongation. The improved mechanical properties can lead to advantages in handling and use. The higher modulus and higher elongation enable the film to be used in dynamic bending applications. Aromatic polymers can generally withstand higher temperatures without degradation. Thus, for the purposes of this disclosure, aromatic polymers will have advantages over semi-aromatic polymers, where the filled polyimide layer is exposed to high temperatures for long periods of time. The exposure to elevated temperatures may be continuous or cumulative (several hours each and several times used). High temperature is intended to mean a temperature above ambient temperature. The polyimides of the present disclosure typically have a Tg of 320 ℃ to 350 ℃. The polyimides of the present disclosure typically have a Coefficient of Thermal Expansion (CTE) of-5 to 10ppm/° c, as measured by TMA from 50-250 ℃.

In some embodiments, the dianhydrides (or diamines) used to form the polyimides disclosed herein may optionally comprise reactive end groups. Some of these reactive end groups may be nadic acid, acetylene, n-propargyl, cyclohexenyl, maleic acid, n-styryl, phenylethynyl. These reactive end groups can be used to end cap the polymer to form a lower molecular weight polymer or to aid in crosslinking of the polymer. Crosslinking of the polymer can increase the Tg as well as the mechanical modulus of the polymer.

White pigment particle filler

The filled polyimide layer contains a white pigment particulate filler. The amount of white pigment particulate filler required to achieve high reflectivity is less than that required without the polyimide of the present disclosure. The white pigment particulate filler is present in an amount between and optionally including any two of the following values: 20,25,30,35,40,45 and 50 wt% filled polyimide film. In some embodiments, the white pigment particulate fillerIs present in an amount of 20 to 50 wt% of the filled polyimide film. In some embodiments, the white pigment particulate filler is selected from the group consisting of zirconia, calcium oxide, silica, zinc oxide, alumina, zinc sulfide, calcium sulfate, barium sulfate, lead carbonate, lead hydroxide, basic zinc molybdate, basic calcium zinc molybdate, lead white, molybdenum white, and lithopone. In another embodiment, the white pigment particulate filler is titanium dioxide (TiO)₂). In some embodiments, the white pigment particle filler may have a coating that completely or partially covers the surface of the pigment particles, so long as the coating does not adversely affect the reflectance upon heat aging, whiteness, or any other desired characteristic of the present disclosure including reflectance and color stability.

In some embodiments, the white pigment may be surface treated with a coupling agent or dispersant, so long as the surface treatment does not negatively impact the advantages of the light emitting diode assembly.

The use of fine (small) particles with a narrow particle size distribution tends to result in a smooth (glossy) surface and higher reflectivity. It is generally known that rough surfaces tend to have irregular surfaces that scatter light widely in various directions. Smooth surfaces (with fewer protrusions on the surface) tend to be glossy reflective. In some embodiments, the white pigment particulate filler has an average particle size of less than 1.9 microns. In some embodiments, the white pigment particulate filler has an average particle size of less than 1.5 microns. In another embodiment, the white pigment particulate filler has an average particle size of less than 1 micron. Particle size was measured using a Horiba LA-930 laser scattering particle size distribution analyzer. In some embodiments, the white pigment particulate filler or slurry thereof may be milled to obtain the desired particle size and to break up any large particle agglomerates that may be present.

Filled polyimide layer

The filled polyimide layers of the present disclosure can be prepared by any method well known in the art of filled polyimide film preparation. In some embodiments, the polyimide is prepared by a chemical conversion process. In one embodiment, one such method includes preparing a white pigment particulate filler slurry. The slurry may be milled or not milled using ball milling or continuous media milling to achieve the desired particle size. The slurry may or may not be filtered to remove any residual large particles. The polyamic acid prepolymer solution is prepared by reacting a dianhydride with a slight excess of diamine. The polyamic acid solution was mixed with the white pigment particle filler slurry in a high shear mixer. The amounts of polyamic acid solution, white pigment particle filler slurry, and finishing solution can be adjusted to achieve a desired loading level of white pigment particle filler and a desired viscosity for film formation. The mixture can be metered through a slot die and cast or manually cast onto a smooth stainless steel belt or substrate to produce a gel film. The conversion chemicals may be metered using a slot die prior to casting. To convert to solids contents greater than 98%, the gel film must typically be dried at high temperatures (convection heating from 200-300 ℃ and radiant heating from 400-800 ℃), which will tend to drive the imidization reaction to completion.

Less white pigment particulate filler is required to achieve the desired whiteness and reflectance. Thus, the filled polyimide layer maintains good mechanical properties. In some embodiments, the filled polyimide layer has at least 500kpsi (35162 kg/cm)²) The modulus of (a). In some embodiments, the filled polyimide layer has at least 900kpsi (63291 kg/cm)²) The modulus of (a). Tensile modulus was determined by ASTM D-882.

In some embodiments, the filled polyimide layer has an elongation of at least 50% as determined by ASTM D-882. An elongation of at least 50% is sufficient for flex circuit applications.

The thickness of the filled polyimide layer depends on the application. Some applications may require thicker layers due to the transparency of the polyimides of the present disclosure. In some embodiments, the filled polyimide layer has a thickness of 25 to 130 micrometers.

Another advantage is that the filled polyimide layer can withstand harsh soldering steps (solder reflow or solder coating) in which electrically conductive traces are formed. White polyethylene terephthalate (PET) generally has a reflectance comparable to the filled polyimide layer of the present disclosure. Generally, during the imaging process, white PET is deformed under soldering conditions, and thus conductive circuit traces cannot be formed on the PET film. The filled polyimide layers of the present disclosure typically have a Tg of 320 ℃ to 340 ℃. The filled polyimide layers of the present disclosure have a CTE, as measured by TMA from 50-250 ℃, of 15 to 25ppm/° c. The filled polyimide has a filled polyimide layer first surface and a filled polyimide layer second surface. Conductive line traces are formed on the filled polyimide layer first surface without significant reflectivity reduction or color change. In some embodiments, conductive line traces are formed on the filled polyimide layer first surface and the filled polyimide layer second surface without significant reflectivity reduction or color change. The conductive line traces provide electrical connections for one or more light emitting diodes.

In some embodiments, the filled polyimide layer further comprises an adhesive layer. The adhesive layer will be adjacent to the filled polyimide layer second surface. In some embodiments, the adhesive layer is an epoxy. In one embodiment, the adhesive is comprised of an epoxy resin and a hardener and optionally further comprises additional components, such as elastomer reinforcing agents, cure accelerators, fillers and flame retardants, depending on the desired characteristics. In some embodiments, the epoxy resin is selected from the group consisting of bisphenol a type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, biphenyl aralkyl type epoxy resins, dicyclopentadiene type epoxy resins, multifunctional type epoxy resins, naphthalene type epoxy resins, phosphorous type epoxy resins, rubber modified epoxy resins, and mixtures thereof.

In another embodiment, the adhesive layer is an acrylic adhesive or a methacrylic adhesive (herein "acrylic" and/or "methacrylic" will be denoted as "(meth) acrylic"). In some embodiments, the adhesive layer is a pressure sensitive (meth) acrylic adhesive. The (meth) acrylic pressure-sensitive adhesive is generally prepared by copolymerizing suitable (meth) acrylic acid with an alkyl ester and may include suitable tackifiers, plasticizers, and other additives as needed to adjust characteristics. Pressure sensitive (meth) acrylic adhesives are well known and need not be described in great detail herein.

In some embodiments, the filled polyimide layer is a multilayer film having a first layer and a second layer. The first layer consists essentially of:

A. a polyimide in an amount from 60 to 75 weight percent of the first layer, the polyimide derived from:

B. a white pigment particulate filler in an amount of from 20 to 30% by weight of the first layer. As the amount of filler increases, the film tends to become more brittle, which makes the film more difficult to handle during the production process. Thus, the second layer comprises an unfilled polyimide, which may be the same or different from the polyimide in the first layer. The second layer allows the filled polyimide layer to retain acceptable mechanical and electrical properties. In some embodiments, the second layer contains a filler. The amount of filler in the second layer should be no greater than 20 wt% based on the total weight of the second layer. The first layer may be directly bonded to the second layer by lamination, coating, or coextrusion. The first layer may be indirectly bonded to the second layer by means of an adhesive. Conductive line traces are formed on the first layer without significant reflectivity reduction or color change. When the filled polyimide layer is used in a light emitting diode assembly, a single Light Emitting Diode (LED) or a plurality of LEDs may be connected to the conductive traces of the first layer by soldering. In another embodiment, the LEDs are connected to portions of the first layer that are free of conductive traces.

Light emitting diode assembly

One embodiment of the present disclosure is a light emitting diode assembly comprising:

A. a filled polyimide layer of the present disclosure having a filled polyimide layer first surface and a filled polyimide layer second surface;

The light emitting diode assemblies of the present disclosure can be prepared by methods well known in the art. In some embodiments, the light emitting diode assembly is obtained by:

a) a photoresist is applied to the filled polyimide film in the region to be patterned,

b) the pattern is exposed and developed in the photoresist,

c) etching to remove the unprotected metal,

d) the anti-corrosion protective material is stripped off,

e) a solder mask is applied to protect the area in a subsequent step,

f) solder (solder reflow or solder coating) is applied,

g) at least part of the solder (excess solder) is removed,

the excess solder is solder that does not form a chemical bond with a conductive metal, typically copper. In some embodiments, excess solder is removed by hot oil or hot air, commonly referred to as solder leveling.

h) One or more LEDs are connected. In some embodiments, the LEDs are directly connected to the conductive trace by soldering. In another embodiment, the LED is connected to the portion of the filled polyimide first surface free of conductive traces by electrical connection using, but not limited to, adhesive or mechanical means and using two-wire leads. In some embodiments, the LED may be attached using an adhesive in addition to the solder.

i) An encapsulant is applied to cover the exposed surfaces of the light emitting diodes. The encapsulant material may also cover a portion of the filled polyimide layer first surface or the entire filled polyimide layer first surface. In some embodiments, the encapsulating material is a silicone or epoxy. The encapsulating material provides environmental and mechanical protection. The encapsulating material may further include a phosphor or a combination of phosphors for wavelength conversion. In some embodiments, the encapsulating material may also act as a lens. In another embodiment, a light emitting diode assembly includes a light scattering lens disposed over an encapsulant material.

In some implementations, an epoxy housing is also added during patterning to include the LED. After the wire bonds are formed, an encapsulant material is then added to fill the epoxy casing.

An advantage of the disclosed light emitting diode assembly is that the filled polyimide layer has:

i) a color L value of at least 85. In some embodiments, the light emitting diode circuit board substrate has a color L value of at least 90. The color L value is defined as CIE1976 (L, a, b) color space, which is determined by ASTM E308[10 ° observer and illuminant D65 ]. A color L value of 100 is considered to be pure white.

ii) a reflectivity of at least 80%. For LEDs, the more light reflected, the brighter, the more efficient the LED is. In some embodiments, the filled polyimide layer has a reflectivity of at least 85%. The reflectance is measured according to ASTM E1164. Thus, the light emitting diode assembly does not require additional reflective surfaces, such as PET reflective tape or metal coatings to enhance and direct light out of the LED. The light emitting diode assembly of the present disclosure has a simplified structure, is produced, and can provide a reduced weight since an additional reflective surface is not required.

Yet another advantage of the light emitting diode assembly is that the reflectivity and color of the filled polyimide layer can be maintained during thermal aging from the typical operating environment in use or thermal cycling of the LED module ranging from ambient temperature to 70 ℃.

In some embodiments, for the light emitting diode assembly, the polyimide is derived from 90 mole% 3,3',4,4' -biphenyltetracarboxylic dianhydride and 100 mole% 2,2' -bis (trifluoromethyl) benzidine, and the white pigment particulate filler is titanium dioxide. In another embodiment, for the light emitting diode assembly, the polyimide is derived from 100 mole% 3,3',4,4' -biphenyltetracarboxylic dianhydride and 100 mole% 2,2' -bis (trifluoromethyl) benzidine, and the white pigment particulate filler is titanium dioxide.

The filled polyimide layer of the light emitting diode assembly may optionally include reinforcing fillers, additives, and the like, so long as they do not adversely affect the advantages of the light emitting diode assembly. In some embodiments, examples of additives that do not adversely affect the advantages of the light emitting diode assemblies of the present disclosure are, but are not limited to, black pigments or matting agents. In some embodiments, a small amount of blue pigment may be added. In small amounts, blue pigments visually enhance and/or balance the white color. A small amount of blue pigment is intended to mean 1 wt% or less. In some embodiments, blue pigments such as cobalt pigments, copper pigments, iron pigments, aluminum pigments, or mixtures thereof may be used. In one embodiment, an aluminum pigment is used. In some embodiments, the filled polyimide layer additionally consists essentially of a sodium aluminum sulfosilicate pigment (ultramarine pigment) in an amount between and optionally including any two of the following values: 0.01,0.05,0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8,0.9 and 1 wt% of a filled polyimide layer. In some embodiments, the filled polyimide layer additionally consists essentially of a sodium aluminum sulfosilicate pigment (ultramarine pigment) in an amount of 0.01 to 1 weight percent of the filled polyimide layer.

In some embodiments, the light emitting diode assembly further comprises a solder resist layer. The solder mask consists essentially of:

i) a polyimide in an amount of 50 to 75 wt% of the solder resist layer, the polyimide derived from:

a white pigment particulate filler having an average particle size of less than 1.9 microns and a content of 20 to 50 wt% of the solder mask layer; in some embodiments, the thickness of the solder mask layer is between and optionally includes any two of the following values: 12,15,20,30,40,50,60,70,80,90,100,110,120 and 130 microns. In some embodiments, the solder mask layer has a thickness of 12 to 130 micrometers. In another embodiment, the solder mask layer has a thickness of 12 to 60 micrometers.

Broadly speaking, reflective solder masks are known; see, for example, U.S. patent 7,431,479 to Weaver et al, which discloses electrically insulating solder resists such as photosensitive epoxies, photosensitive polyimides, and multilayer reflector sheets. Weaver et al disclose that the reflectivity of the solder mask can be increased for sufficiently high concentrations of filler material. As the amount of filler increases, the film tends to become more brittle, which makes the film more difficult to handle during the production process. Conventional reflective solder masks may suffer from problems for any of a number of reasons, such as: i. insufficient whiteness, ii. insufficient reflectance, iii. poor reflectance and poor color stability after a period of heat exposure (i.e. poor heat aging), iv. poor mechanical properties, color stability with time difference of v.uv exposure (i.e. poor UV aging), and vi. distortion and discoloration during welding. There is therefore a need for an improved reflective solder mask.

In one embodiment, the solder mask of the present disclosure has a reflectivity of at least 80%. In another embodiment, the solder mask has a reflectivity of at least 85%. The reflectance is measured according to ASTM E1164. The reflectivity can be obtained without additionally having a reflective surface on the solder resist layer. Therefore, additional reflective surfaces are generally not required to enhance and direct the light. The solder mask of the present disclosure simplifies construction and production by eliminating the need for additional reflective surfaces. Solder masks with more than one layer are furthermore prone to delamination and or curling.

The solder mask layer has a color L value of at least 85. In some embodiments, the solder mask layer has a color L value of at least 90. The color L value is defined according to CIE1976 (L, a, b) color space. A color L value of 100 is considered to be pure white.

Yet another advantage of the solder mask of the present disclosure is the ability to maintain reflectivity and color during thermal aging. Another advantage of the solder mask of the present disclosure is that it does not discolor during soldering. White PET typically has a reflectivity comparable to the filled polyimide layer of the present disclosure. In general, white PET is deformed under soldering conditions during image processing, and thus cannot be used as a solder resist. The solder resist of the present disclosure shows: i. sufficient whiteness, ii. sufficient reflectance, iii. sufficient heat aging, iv. sufficient mechanical properties, and v. no deformation or discoloration during welding.

The solder mask may optionally include reinforcing fillers, additives, etc., as long as they do not adversely affect the advantages of the solder mask of the present disclosure. In some embodiments, examples of additives that do not adversely affect the benefits of the solder mask of the present disclosure are, but are not limited to, black pigments or matting agents. In some embodiments, a small amount of blue pigment may be added. In small amounts, blue pigments visually enhance and/or balance the white color. In some embodiments, blue pigments such as cobalt pigments, copper pigments, iron pigments, aluminum pigments, or mixtures thereof may be used. In one embodiment, an aluminum pigment is used. In some embodiments, the solder mask layer additionally comprises a sodium aluminum sulfosilicate pigment (ultramarine pigment) in an amount of 0.01 to 1 wt% of the solder mask layer.

The solder resist of the present disclosure shows: i. sufficient whiteness, ii. sufficient reflectance, iii. sufficient heat aging, iv. sufficient mechanical properties, and v. no deformation or discoloration during welding. The combination of the solder mask layer and the light emitting diode assembly filled polyimide layer of the present disclosure results in a light emitting diode assembly with increased reflectivity compared to if only one of them is used. When used in combination, all exposed surfaces are reflective, which further enhances and redirects light from the connected LEDs.

In some embodiments, the light emitting diode assembly comprises:

A. a filled polyimide layer having a filled polyimide layer first surface and a filled polyimide layer second surface; the filled polyimide layer comprises:

In some embodiments, the light emitting diode assembly comprises:

A. a filled polyimide layer having a filled polyimide layer first surface and a filled polyimide layer second surface; the filled polyimide layer consists essentially of:

sodium aluminum sulfosilicate pigment in an amount of 0.01 to 1 weight percent of the filled polyimide layer;

In another embodiment, for any of the above light emitting diode assembly embodiments, the white pigment particulate filler is titanium dioxide. In another embodiment, for any of the light emitting diode assembly embodiments described above, the polyimide is derived from at least 50 mole% of 3,3',4,4' -biphenyltetracarboxylic dianhydride, based on the total dianhydride content of the polyimide. In another embodiment, for any of the light emitting diode assembly embodiments described above, the polyimide is derived from at least 90 mole% 3,3',4,4' -biphenyltetracarboxylic dianhydride and 100 mole% 2,2' -bis (trifluoromethyl) benzidine. In another embodiment, for any of the light emitting diode assembly embodiments described above, the polyimide is derived from 100 mole% 3,3',4,4' -biphenyltetracarboxylic dianhydride and 100 mole% 2,2' -bis (trifluoromethyl) benzidine.

In another embodiment, when the polyimide is derived from at least 45 mole% of 3,3',4,4' -biphenyltetracarboxylic dianhydride, based on the total dianhydride content of the polyimide, the polyimide is additionally derived from not more than 55 weight% of 4,4' - (hexafluoroisopropylidene) phthalic anhydride (6FDA), based on the total dianhydride content of the polyimide.

In another embodiment, when the polyimide is derived from at least 45 mole percent of 3,3',4,4' -biphenyltetracarboxylic dianhydride, based on the total dianhydride content of the polyimide, the polyimide is additionally derived from no more than 55 weight percent of pyromellitic dianhydride, based on the total dianhydride content of the polyimide.

In another embodiment, when the polyimide is derived from at least 45 mole percent of 3,3',4,4' -biphenyltetracarboxylic dianhydride, based on the total dianhydride content of the polyimide, the polyimide is additionally derived from no more than 55 weight percent of 4,4' -oxydiphthalic anhydride (ODPA), based on the total dianhydride content of the polyimide; 4,4'- (4,4' -isopropylidenediphenoxy) bis (phthalic anhydride) (BPADA); 2,3,3',4' -biphenyltetracarboxylic dianhydride; 2,2',3,3' -biphenyltetracarboxylic dianhydride or a mixture thereof.

In another embodiment, when the polyimide is derived from at least 45 mole percent of 3,3',4,4' -biphenyltetracarboxylic dianhydride, based on the total dianhydride content of the polyimide, the polyimide is additionally derived from not more than 55 weight percent of diphenylsulfonetetracarboxylic dianhydride (DSDA), based on the total dianhydride content of the polyimide; 4,4' -bisphenol a dianhydride; 1,2,3, 4-cyclobutanetetracarboxylic dianhydride; (-) - [1S, 5R, 6S ] -3-oxabicyclo [3.2.1] octane-2, 4-dione-6-spiro-3- (tetrahydrofuran-2, 5-dione); bicyclo [2.2.2] oct-7-ene-2, 3,5, 6-tetracarboxylic acid dianhydride, 9, 9-disubstituted xanthene or a mixture thereof.

In some embodiments, the light emitting diode assembly comprises:

D. an encapsulant covering the exposed surface of the light emitting diode and the at least partially filled polyimide layer first surface; and

E. a solder mask, the solder mask comprising:

a white pigment particulate filler having an average particle size of less than 1.9 microns and a content of 20 to 50 wt% of the soldermask layer.

In some embodiments, the light emitting diode assembly comprises:

E. a solder mask consisting essentially of:

In another embodiment, the light emitting diode assembly comprises:

E. a solder mask, the solder mask comprising:

a white pigment particulate filler having an average particle size of less than 1.9 microns and a content of 20 to 50 wt% of the solder mask layer; and

sodium aluminium sulfosilicate pigment, in an amount of 0.01 to 1 wt% of the solder mask.

In another embodiment, the light emitting diode assembly comprises:

E. a solder mask consisting essentially of:

In some embodiments, for any of the light emitting diode assembly embodiments described above, the white pigment particle filler of the filled polyimide layer and the white pigment particle filler of the solder mask layer are independently titanium dioxide or both titanium dioxide.

In another embodiment, for any of the light emitting diode assembly embodiments described above, the polyimide of the filled polyimide layer and the polyimide of the solder mask layer are independently derived from (or are both derived from) at least 50 mole percent of 3,3',4,4' -biphenyltetracarboxylic dianhydride based on the total dianhydride content of the polyimide. In another embodiment, for any of the light emitting diode assembly embodiments described above, the polyimide of the filled polyimide layer and the polyimide of the solder mask layer are independently derived from (or are both derived from) 90 mole% 3,3',4,4' -biphenyltetracarboxylic dianhydride and 100 mole% 2,2' -bis (trifluoromethyl) benzidine. In another embodiment, for any of the light emitting diode assembly embodiments described above, the polyimide of the filled polyimide layer and the polyimide of the solder mask layer are independently derived from (or are both derived from) 100 mole% 3,3',4,4' -biphenyltetracarboxylic dianhydride and 100 mole% 2,2' -bis (trifluoromethyl) benzidine.

Thermal control blanket

Visible light is a major source of thermal energy in a spatial environment. Thermal control coatings (thermal control blankets) are used on photosensitive spacecraft or satellite components to prevent overheating. Broadly speaking, reflective materials for thermal control blankets are known; see, e.g., Roth et al U.S. Pat. No. 7,270,891 and Long et al WO 02/097829.

Conventional thermal control blankets may suffer from problems for any of a number of reasons, such as insufficient reflectivity, poor adhesion, composite structures, expensive materials or polymers, polymers with low Tg and/or high CTE that are not suitable for use in the extreme thermal environment of space that may occur when exposed to direct sunlight. While white polyethylene terephthalate has good reflectivity, polyethylene terephthalate cannot withstand long term exposure to low earth orbit space environments; see Waters et al, "Changes in optics and thermal Properties of the MISSE2PEACE Polymers and Spacecraft Silicones"; international discussion of Materials in Space Environment in 11 th world (International Symposium on Materials in Space Environment), 9.9.18.2009 (Aix en Provence, France). Multilayer coatings or laminates are problematic due to poor adhesion between layers, resulting in increased costs due to more complex production and additional material costs. It is also desirable to reduce the basis weight of the thermal control blanket. There is therefore a need for a low cost, improved thermal control blanket.

One embodiment of the present disclosure is a thermal control blanket comprising a filled polyimide layer. The filled polyimide layer consists essentially of polyimide, a white pigment particulate filler, and an electrically conductive filler. The polyimide is present in an amount between and including any two of the following values: 50,55,60,65,70 and 75 wt% of a filled polyimide layer. In some embodiments, the polyimide is present in an amount of 50 to 75 weight percent of the filled polyimide layer. The white pigment particulate filler is present in an amount between and including any two of the following values: 20,25,30,35,40,45 and 50 wt% of a filled polyimide layer. In some embodiments, the white pigment particulate filler is present in an amount of 20 to 50 weight percent of the filled polyimide layer. In some embodiments, the white pigment particulate filler is titanium dioxide.

In some embodiments, the conductive filler is present in an amount between and including any two of the following values: 2,3,4 and 5 wt% of a filled polyimide layer. In some embodiments, the conductive filler is present in an amount of 2 to 5 weight percent of the filled polyimide layer. In some embodiments, the conductive filler is selected from the group consisting of carbon, carbon black, graphite, metal particles, and mixtures thereof. The conductive filler imparts sufficient conductivity to the filled polyimide layer to enable discharge of static charge, thereby preventing destructive flash discharge.

C. a conductive filler in an amount up to 5 weight percent of the filled polyimide layer; the thermal control blanket has a color L value (as determined by ASTM E308[10 ° observer and illuminant D65 ]) of at least 85 and a reflectance (as determined by ASTM E1164) of at least 80%.

In some embodiments, the polyimide is derived from:

a) at least 50 mole%, based on the total dianhydride content of the polyimide, of 3,3',4,4' -biphenyltetracarboxylic dianhydride,

b) at least 50 mole percent 2,2' -bis (trifluoromethyl) benzidine, based on the total diamine content of the polyimide. In some embodiments, the white pigment particulate filler is titanium dioxide.

In one embodiment, the thermal control blanket polyimide is derived from 90 mole% 3,3',4,4' -biphenyltetracarboxylic dianhydride and 100 mole% 2,2' -bis (trifluoromethyl) benzidine, and the white pigment particulate filler is titanium dioxide. In another embodiment, the thermal control blanket polyimide is derived from 100 mole% 3,3',4,4' -biphenyltetracarboxylic dianhydride and 100 mole% 2,2' -bis (trifluoromethyl) benzidine, and the white pigment particulate filler is titanium dioxide. In another embodiment, the thermal control blanket polyimide is additionally derived from not more than 55 weight percent 4,4' -oxydiphthalic anhydride (ODPA), based on the total dianhydride content of the polyimide; 4,4'- (4,4' -isopropylidenediphenoxy) bis (phthalic anhydride) (BPADA); 2,3,3',4' -biphenyltetracarboxylic dianhydride; 2,2',3,3' -biphenyltetracarboxylic dianhydride or a mixture thereof. In another embodiment, the thermal control blanket polyimide is additionally derived from not more than 55 weight percent of diphenyl sulfone tetracarboxylic dianhydride (DSDA) based on the total dianhydride content of the polyimide; 4,4' -bisphenol a dianhydride; 1,2,3, 4-cyclobutanetetracarboxylic dianhydride; (-) - [1S, 5R, 6S ] -3-oxabicyclo [3.2.1] octane-2, 4-dione-6-spiro-3- (tetrahydrofuran-2, 5-dione) [ and bicyclo [2.2.2] oct-7-ene-2, 3,5, 6-tetracarboxylic dianhydride, 9, 9-disubstituted xanthene and mixtures thereof. In another embodiment, the thermal control blanket polyimide is additionally derived from not more than 55 weight percent 4,4' - (hexafluoroisopropylidene) phthalic anhydride (6FDA) based on the total dianhydride content of the polyimide. In another embodiment, the thermal control blanket polyimide is additionally derived from not more than 55 weight percent pyromellitic dianhydride, based on the total dianhydride content of the polyimide. In another embodiment, the thermal control blanket polyimide is additionally derived from no more than 50 mole percent of trans-1, 4-diaminocyclohexane, based on the total diamine content of the polyimide; 3, 5-diaminobenzotrifluoride; 2- (trifluoromethyl) -1, 4-phenylenediamine; 1, 3-diamino-2, 4,5, 6-tetrafluorobenzene; 2, 2-bis (3-aminophenyl) 1,1,1,3,3, 3-hexafluoropropane; 2,2' -bis- (4-aminophenyl) -hexafluoropropane (6F diamine); 3,4' -diaminodiphenyl ether (3,4' -ODA), m-phenylenediamine (MPD), 4, 4-bis (trifluoromethoxy) benzidine, 3,3' -diamino-5, 5' -trifluoromethylbiphenyl, 3,3' -diamino-6, 6' -trifluoromethylbiphenyl, 3,3' -bis (trifluoromethyl) benzidine; 2, 2-bis [4- (4-aminophenoxy) phenyl ] hexafluoropropane (4-BDAF),4,4 '-diaminodiphenyl sulfide (4,4' -DDS); 3,3 '-diaminodiphenyl sulfone (3,3' -DDS); 4,4' -diaminodiphenyl sulfone; 2,2' -bis (dimethyl) benzidine; 3,3' -bis (dimethyl) benzidine; 4,4 '-trifluoromethyl-2, 2' -diaminobiphenyl and derivatives thereof.

According to the present disclosure, the thermal control blanket has a high reflectivity. Therefore, an additional reflective layer such as silicon or germanium is not required to obtain high reflectivity. The thermal control blanket of the present disclosure simplifies the structure, production process and provides reduced weight.

The thermal control blanket typically has mechanical properties that are superior to films made with semi-aromatic polymers. Aromatic polymers generally exhibit better UV stability, and better mechanical properties such as modulus or elongation. The higher the modulus (strength), the thinner the film can be made. Thinner membranes enable smaller assemblies to be produced and at lower cost. The higher modulus and higher elongation enable the film to be used in dynamic bending applications. Aromatic polymers can generally withstand higher temperatures without degradation. The exposure to elevated temperatures may be continuous or cumulative (several hours each and several times used).

In some embodiments, the thermal control blanket has at least 500kpsi (35162 kg/cm)²) The modulus of (a). In some embodiments, the thermal control blanket has at least 900kpsi (63291 kg/cm)²) The modulus of (a). Modulus was determined by ASTM D-882.

Another advantage is that the polyimide has a light color before the pigment is added. Thus, the addition of the white pigment particulate filler creates a thermal control blanket having:

i) a color L value of at least 85. In some embodiments, the thermal control blanket has a color L value of at least 90. The color L value is defined as CIE1976 (L, a, b) color space, which is determined by ASTM E308[10 ° observer and illuminant D65 ]. A color L value of 100 is considered to be pure white.

ii) a reflectivity of at least 80%. In some embodiments, the thermal control blanket has a reflectivity of at least 85%. The reflectance is measured according to ASTM E1164. In addition, less white pigment particle filler is required to obtain the color L value and reflectance, thereby maintaining good mechanical properties.

Other advantages of the thermal control blanket of the present disclosure are the ability to maintain reflectivity and color during thermal aging and the ability to resist long term low earth track exposure.

It is desirable for the thermal control blanket to have greater than 60% solar reflection, less than 20% solar absorption, and less than 30% solar transmission, all measured according to ASTM E1105 (air mass-0, close to normal incidence angle (= <15 °)), average of the two directions in the plane. Further, it is desirable for the thermal control blanket to have an infrared reflectance of less than 20%, an infrared emissivity of greater than 80%, and an infrared transmittance of less than 5%, all measured according to astm e408 (300K black body weight, near normal incidence angle (= <15 °)), average of the two directions in the plane. The thermal control blanket of the present disclosure has a solar reflection of 65%, a solar absorption of 15%, and a solar transmission of 20%, all measured according to ASTM E1105 (air mass-0, near normal incidence angle (= <15 °)), average of the two directions on the plane. Further, the thermal control blanket of the present disclosure has an infrared reflectance of 17%, an infrared emissivity of 83%, and an infrared transmittance of 0%, all measured according to ASTM E408 (300K black body weight, near normal incidence angle (= <15 °)), average of the two directions on the plane. Thus, the thermal control blanket of the present disclosure achieves at least as good as or better than conventional thermal control blankets.

The filled polyimide layer of the thermal control blanket may optionally contain reinforcing fillers or other additives so long as they do not adversely affect the advantages of the thermal control blanket of the present disclosure. In some embodiments, examples of additives that do not adversely affect the advantages of the thermal control blanket of the present disclosure are, but are not limited to, black pigments or matting agents in an amount greater than 5 weight percent. In some embodiments, the amount of conductive filler can be tailored to provide a potential for electrostatic discharge while exhibiting small changes in reflectivity. In some embodiments, a small amount of blue pigment may be added. In small amounts, blue pigments visually enhance and/or balance the white color. In some embodiments, blue pigments such as cobalt pigments, copper pigments, iron pigments, aluminum pigments, or mixtures thereof may be used. In one embodiment, aluminum pigments are used. In some embodiments, the filled polyimide layer additionally consists essentially of sodium aluminum sulfosilicate pigment (ultramarine pigment) in an amount between and optionally including any two of the following amounts: 0.01,0.05,0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8,0.9 and 1 wt% of a filled polyimide layer. In some embodiments, the filled polyimide layer additionally consists essentially of a sodium aluminum sulfosilicate pigment (ultramarine pigment) in an amount of 0.01 to 1 weight percent of the filled polyimide layer.

In some embodiments, the thermal control blanket is attached to a substrate. In some embodiments, the substrate is a metal. In another embodiment, the substrate is a polymer. In some embodiments, the thermal control blanket may be directly attached to the substrate by lamination or coextrusion. In some embodiments, the thermal blanket is adhered to the substrate using an adhesive. In some embodiments, the adhesive layer is an epoxy. In one embodiment, the adhesive layer is comprised of an epoxy resin and a hardener and optionally further comprises additional components, such as elastomer reinforcing agents, cure accelerators, fillers and flame retardants, depending on the desired characteristics. In some embodiments, the epoxy resin is selected from the group consisting of bisphenol a type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, biphenyl aralkyl type epoxy resins, dicyclopentadiene type epoxy resins, multifunctional type epoxy resins, naphthalene type epoxy resins, phosphorous type epoxy resins, rubber modified epoxy resins, and mixtures thereof.

In another embodiment, a (metal oxide) adhesion promoter may be applied to the thermal control blanket to enhance the adhesion of the thermal control blanket to the substrate. The adhesive or adhesion promoter may be applied to one or both sides of the thermal control blanket by vacuum deposition, atomic layer deposition, or plasma deposition. In some embodiments, the thermal control blanket further comprises an adhesive layer on at least one side of the thermal control blanket. In another embodiment, the thermal control blanket further comprises an adhesion promoter layer on at least one side of the thermal control blanket. In some embodiments, the thermal control blanket further comprises an adhesive on at least one side of the thermal control blanket, wherein the adhesive is an epoxy adhesive, an acrylic adhesive, or a methacrylic adhesive. In some embodiments, the thermal control blanket further comprises a metal oxide adhesion promoter layer on at least one side of the thermal control blanket.

In some embodiments, the thermal control blanket comprises a filled polyimide layer; the filled polyimide layer comprises:

C. the content of the conductive filler is 2 to 5 wt% of the filled polyimide layer; wherein the thermal control blanket has a color L value (as determined by ASTM E308[10 ° observer and illuminant D65 ]) of at least 85 and a reflectance (as determined by ASTM E1164) of at least 80%.

In some embodiments, the thermal control blanket comprises a filled polyimide layer; the filled polyimide layer consists essentially of:

C. the content of the conductive filler is 2 to 5 wt% of the filled polyimide layer;

D. a sodium aluminum sulfosilicate pigment in an amount of 0.01 to 1 weight percent of the filled polyimide layer; wherein the thermal control blanket has a color L value (as determined by ASTM E308[10 ° observer and illuminant D65 ]) of at least 85 and a reflectance (as determined according to ASTM E1164) of at least 80%.

C. the conductive filler is present in an amount of 2 to 5 weight percent of the filled polyimide layer and is selected from the group consisting of carbon, carbon black, graphite, metal particles, and mixtures thereof; wherein the thermal control blanket has a color L value (as determined by ASTM E308[10 ° observer and illuminant D65 ]) of at least 85 and a reflectance (as determined by ASTM E1164) of at least 80%.

C. the conductive filler is present in an amount of 2 to 5 weight percent of the filled polyimide layer and is selected from the group consisting of carbon, carbon black, graphite, metal particles, and mixtures thereof; wherein the thermal control blanket has a color L value (as determined by ASTM E308[10 ° observer and illuminant D65 ]) of at least 85 and a reflectance of at least 80% (determined according to ASTM E1164), and the thermal control blanket further comprises i) an adhesive on at least one side of the thermal control blanket, wherein the adhesive is an epoxy adhesive, an acrylic adhesive, or a methacrylic adhesive, or ii) a metal oxide adhesion promoter layer on at least one side of the thermal control blanket.

In some embodiments, for any of the thermal control blanket embodiments described above, the white pigment particulate filler is titanium dioxide.

In another embodiment, for any of the above thermal control blanket embodiments, the polyimide is derived from at least 50 mole% of 3,3',4,4' -biphenyltetracarboxylic dianhydride, based on the total dianhydride content of the polyimide. In another embodiment, for any of the above thermal control blanket embodiments, the polyimide is derived from 90 mole% 3,3',4,4' -biphenyltetracarboxylic dianhydride and 100 mole% 2,2' -bis (trifluoromethyl) benzidine. In another embodiment, for any of the above thermal control blanket embodiments, the polyimide is derived from 100 mole% 3,3',4,4' -biphenyltetracarboxylic dianhydride and 100 mole% 2,2' -bis (trifluoromethyl) benzidine.

All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification, including definitions, will control.

Although methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, suitable methods and materials are described herein.

Examples

The materials, methods, and examples herein are illustrative only and, unless specifically indicated, are not intended to be limiting. Although methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, suitable methods and materials are described herein.

The following glossary contains the names and abbreviations for each of the ingredients used:

metallized PET:2.0 mil (50.8 micron) double sided aluminum metallized polyester film available from DuPont-Teijin Films

0.17 mil (4.3 microns) aramid Film, available from Teijin Advanced Film Co.

White solder resist layer: SSR-6300S liquid photoimageable solder resist ink available from San-Ei Kagaku Co.Ltd. (Japan).

50EN polyimide film with 0.50 mil thick white epoxy coating:

purchased from Toray-DuPont Company, Ltd. (Japan)

White PET:300XMWH11, available from DuPont Teijin Films (U.S.)

Color L value, as defined by CIE1976 (L, a, b) color space (L =0 produces black, L =100 shows diffuse white), determined by ASTM E308[10 ° observer and illuminant D65]

The reflectance (percent reflectance) was determined by ASTM E1164 (400-700 nm in 10nm increments). Hunterlabs colorquest xe.d65/10 illuminator/viewer. The average of three measurements was taken for each sample.

Tensile modulus was determined by ASTM D-882.

Elongation is determined by ASTM D-882.

Resistance to float welding was determined by IPC TM650, method 2.4.13 a.

Particle size was measured using a Horiba LA-930 laser scattering particle size distribution analyzer.

Example 1

Example 1 illustrates that the filled polyimide layer of the present disclosure has higher reflectance and color L value compared to other polyimides having the same content of titanium dioxide.

The basic polyamic acid prepolymer was prepared as follows: the 3,3',4,4' -biphenyltetracarboxylic dianhydride [ BPDA ] was polymerized with 2,2 'bis (trifluoromethyl) benzidine [ TFMB ] to about 100 poise and the polyamic acid solids in N, N' -dimethylacetamide [ DMAc ] was 23 wt%. A portion of the prepolymer was retained to make a titanium dioxide slurry. The remaining prepolymer solution was chain-amplified by adding a stoichiometric amount of 6 wt% PMDA in DMAc or, alternatively, an equal stoichiometric amount of BPDA solids such that the resulting solution had a viscosity of about 3000 poise.

A titania slurry was prepared from 58 wt% DMAc, 6.4 wt% BPDA/TFMB polyamic acid prepolymer solution prepared as above (23 wt% solution in DMAc), 35 wt% titania powder (DuPont)R-706) and 0.05% by weight of ultramarine blue inorganic pigment (Nubicoat HWR from Nubiola). The ingredients were thoroughly mixed in a rotor stator high speed dispersion mill. The median particle size of the slurry was 1.2 microns.

32kg of the titanium dioxide slurry was mixed into 191kg of BPDA/TFMB polyamic acid solution (23 wt% polyamic acid solids in DMAc) in a 50 gallon tank.

The slurry can be mixed into the final polyamic acid solution with a viscosity of 3000 poise or, alternatively, into the prepolymer solution, followed by chain amplification using a stoichiometric amount of 6 wt% PMDA in DMAc solution or an equivalent stoichiometric amount of BPDA solids, such that the resulting solution has a viscosity of-3000 poise. The tank was equipped with three independently controlled stirrer shafts: low speed anchor mixers, high speed disk dispersers and high shear rotor-stator emulsifiers. The speed of the anchor mixer, disperser, and emulsifier is adjusted as needed to ensure effective mixing and dispersion without overheating the mixture. The temperature of the mixture was further adjusted by flowing cooled ethylene glycol through the mixing tank jacket. The final solution was filtered through a 20 micron bag filter and the entrapped air was removed by vacuum degassing. The final polymer/titania mixture was cooled to about-6 ℃, the conversion chemicals acetic anhydride and 3-methylpyridine were metered into the mixture, and the film was cast onto a 90 ℃ drum using a slot die. The resulting gel film was peeled from the drum and fed to a tenter oven where it was dried to 60-75% by weight solids using convective air and then cured to greater than 98% solids content using radiant heat. The results are shown in Table 1.

Example 2

Example 2 illustrates that the filled polyimide layer of the present disclosure has higher reflectance and color L values compared to other non-light colored polyimides with the same amount of titanium dioxide.

The basic polyamic acid prepolymer was prepared as in example 1. A titanium dioxide slurry was prepared from 58 wt% DMAc, 6.4 wt%% BPDA/TFMB polyamic acid prepolymer solution (23 wt% solution in DMAc), 35 wt% titanium dioxide powder (DuPont)R-101) and 0.05% by weight of an ultramarine blue inorganic pigment (Nubicoat HWR from Nubiola). The ingredients were thoroughly mixed in a rotor stator high speed dispersion mill. The median particle size of the slurry was 1.8 microns. 14g of the titanium dioxide slurry was thoroughly mixed into 85g of the remaining polyamic acid solution, and then the strands were amplified to 3000 poise in a 200mL beaker using a stoichiometric amount of 6 wt% PMDA in DMAc. The polymer mixture was degassed under vacuum. The membranes were hand cast to the glass plates using stainless steel casting barsOn a sheet. To comprise wet-cast filmsThe sheet was immersed in a bath consisting of an 50/50 mixture of 3-methylpyridine and acetic anhydride. The bath was slowly stirred for a period of 3 to 4 minutes to produce imidization and gelation of the film. Coating the gel film withThe carrier sheet is peeled off and placed on a needle board frame. After allowing the residual solvent to drain off the film, the pin frame containing the film was placed in an oven at 150 ℃. The oven temperature was gradually increased to 340 ℃ over a period of 45-60 minutes and held at 340 ℃ for 10 minutes. The film was removed from the oven and allowed to cool. The results are shown in Table 1.

Comparative example 1

Comparative example 1 illustrates that other aromatic polyimides with the same amount of titanium dioxide have low reflectance and color L values.

The basic polyamic acid prepolymer was prepared as follows: polymeric pyromellitic dianhydride [ PMDA ]]With 4,4 '-diaminodiphenyl ether [4,4' -ODA ]]To largeAbout 100 poise and N, N' -dimethylacetamide [ DMAc]The polyamic acid solid in (1) was 21 wt%. A portion of the prepolymer was retained to make a titanium dioxide slurry. A titania slurry was prepared from 58 wt% DMAc, 6.4 wt% retained PMDA/ODA polyamic acid prepolymer solution (21 wt% solution in DMAc), 35 wt% titania powder (DuPont)R-706) and 0.05% by weight of ultramarine blue inorganic pigment (Nubicoat HWR from Nubiola). The ingredients were thoroughly mixed in a rotor stator high speed dispersion mill. The median particle size of the slurry was 2.4 microns. In a 200mL flask, 15g of the titanium dioxide slurry was mixed into 80g of the polyamic acid solution. The resulting prepolymer dispersion mixture was chain-amplified by adding a stoichiometric amount of 6 wt% PMDA in DMAc to give a resulting solution with a viscosity of-2000 poise. The resulting polymer mixture was degassed under vacuum. A film was prepared in the same manner as described in example 2. The film was cured in an oven where the temperature was gradually raised to 375 ℃ over a period of 45-60 minutes and held at 375 ℃ for 10 minutes. The film was then removed from the oven and allowed to cool. The results are shown in Table 1.

Comparative example 2

Comparative example 2 illustrates that other aromatic polyimides with the same amount of titanium dioxide have low reflectance and color L values.

The basic copolyamide acid prepolymer was prepared as follows: polymeric pyromellitic dianhydride [ PMDA ]]And 3,3',4,4' -biphenyltetracarboxylic dianhydride (BPDA) with 4,4 '-diaminodiphenyl ether [4,4' -ODA]And 1, 4-diaminobenzene (PPD) to about 100 poise and N, N' -dimethylacetamide [ DMAc]The polyamic acid solid in (1) was 20 wt%. A portion of the prepolymer was retained to make a titanium dioxide slurry. A titanium dioxide slurry was prepared from 58 wt% DMAc, 6.4 wt% retained polyamic acid prepolymer, 35 wt% titanium dioxide powder (DuPont)R-706) and 0.05% by weight of ultramarine blue inorganic pigment (Nubicoat HWR from Nubiola). The ingredients were thoroughly mixed in a rotor stator high speed dispersion mill. The median particle size of the slurry was 2.7 microns. In a 200mL flask, 15g of the titanium dioxide slurry was mixed into 80g of the polyamic acid solution. The resulting prepolymer dispersion mixture was chain-amplified by adding a stoichiometric amount of 6 wt% PMDA in DMAc to give a resulting solution with a viscosity of-2000 poise. The polymer mixture was degassed under vacuum. A film was prepared in the same manner as described in example 2. The film was cured in an oven where the temperature was gradually raised to 375 ℃ over a period of 45-60 minutes and held at 375 ℃ for 10 minutes. The film was then removed from the oven and allowed to cool. The results are shown in Table 1.

TABLE 1

Comparative example 3

An aramid film.

Fig. 1 shows that the unfilled polyimide film of example 1 has a higher transmittance compared to the aramid film, even though the polyamide film is about 6x thicker than the aramid film.

Example 3

Example 3 demonstrates that the filled polyimide layer of the present disclosure has little color and reflectivity change upon heat aging and passes the float test without deformation or color change.

The polyimide was prepared as described in example 1. The change in color L value upon thermal aging is plotted in FIG. 2. The change in reflectivity upon thermal aging is plotted in fig. 3. The float resistance results are described in tables 2 and 3.

Comparative example 4

The white PET is prepared by the method of mixing the PET,300XMWH11。

comparative example 4 shows that while the change in color and reflectance is good upon heat aging, the white PET deforms during the float resistance test.

The change in color L value upon thermal aging is plotted in FIG. 2. The change in reflectivity upon thermal aging is plotted in fig. 3. The float resistance results are described in table 2.

Comparative example 5

50EN had a 0.50 mil thick white epoxy coating.

Comparative example 5 shows that the polyimide with white epoxy coating changes color upon heat aging, has low reflectivity and deforms in the float resistance test.

Comparative example 6

Metallized PET.

Comparative example 6 shows that metallized PET changes color upon heat aging, has low reflectivity, and deforms in the float resistance test.

Comparative example 7

And a white solder mask layer.

Comparative example 7 shows that the white solder mask changes color and reflectance upon heat aging and changes color after the float test.

The change in color L value upon thermal aging is plotted in FIG. 2. The change in reflectivity upon thermal aging is plotted in fig. 3. The float resistance results are described in tables 2 and 3.

TABLE 2

Float resistance test results-visual inspection

TABLE 3

Float resistance test result-color L value

Sample damaged by float test and therefore colour could not be measured

It is noted that not all of the acts described above in the general description or the examples are required, that a portion of a particular act may not be required, and that additional acts other than those described may also be performed. Further, the order in which each of the activities are listed are not necessarily the order in which they are performed. After reading this specification, skilled artisans will be able to determine which behaviors can be used for their specific needs or desires.

In the foregoing specification, the invention has been described with reference to specific embodiments. However, one of ordinary skill in the art appreciates that various changes and modifications can be made without departing from the scope of the present invention as set forth in the claims below. All the elements disclosed in this specification may be replaced by alternative elements serving the same, equivalent or similar purpose. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of present invention.

Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or element of any or all the claims.

When an amount, concentration, or other value or parameter is given as either a range, preferred range, or a list of upper and lower values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions within the range. It is not intended that the scope of the invention be limited to the specific values recited when defining a range.

Claims

1. A light emitting diode assembly comprising:

A. a filled polyimide layer having a filled polyimide layer first surface and a filled polyimide layer second surface; the filled polyimide layer is composed of:

2. The light emitting diode assembly of claim 1, wherein the filled polyimide layer is additionally comprised of sodium aluminum sulfosilicate pigment in an amount of 0.01 to 1 weight percent of the filled polyimide layer.

3. The light emitting diode assembly of claim 1 wherein the white pigment particulate filler is titanium dioxide.

4. The light emitting diode assembly of claim 1 wherein the polyimide is derived from 90 mole% 3,3',4,4' -biphenyltetracarboxylic dianhydride and 100 mole% 2,2' -bis (trifluoromethyl) benzidine and the white pigment particulate filler is titanium dioxide.

5. The light emitting diode assembly of claim 1 wherein the polyimide is derived from 100 mole% 3,3',4,4' -biphenyltetracarboxylic dianhydride and 100 mole% 2,2' -bis (trifluoromethyl) benzidine and the white pigment particulate filler is titanium dioxide.

6. The light emitting diode assembly of claim 1, wherein the polyimide is derived from at least 50 mole% of 3,3',4,4' -biphenyltetracarboxylic dianhydride, based on the total dianhydride content of the polyimide.

7. The light emitting diode assembly of claim 1 wherein the polyimide is additionally derived from no more than 55 weight percent 4,4' -oxydiphthalic anhydride (ODPA) based on the total dianhydride content of the polyimide; 4,4'- (4,4' -isopropylidenediphenoxy) bis (phthalic anhydride) (BPADA); 2,3,3',4' -biphenyltetracarboxylic dianhydride; 2,2',3,3' -biphenyltetracarboxylic dianhydride or a mixture thereof.

8. The light emitting diode assembly of claim 1, wherein the polyimide is additionally derived from not more than 55 weight percent diphenylsulfone tetracarboxylic dianhydride (DSDA) based on total dianhydride content of the polyimide; 4,4' -bisphenol a dianhydride; 1,2,3, 4-cyclobutanetetracarboxylic dianhydride; (-) - [1S, 5R, 6S ] -3-oxabicyclo [3.2.1] octane-2, 4-dione-6-spiro-3- (tetrahydrofuran-2, 5-dione); bicyclo [2.2.2] oct-7-ene-2, 3,5, 6-tetracarboxylic acid dianhydride, 9, 9-disubstituted xanthene or a mixture thereof.

9. The light emitting diode assembly of claim 1 wherein the polyimide is additionally derived from not more than 55 weight percent 4,4' - (hexafluoroisopropylidene) phthalic anhydride (6FDA) based on the total dianhydride content of the polyimide.

10. The light emitting diode assembly of claim 1 wherein the polyimide is additionally derived from not more than 55 weight percent pyromellitic dianhydride, based on the total dianhydride content of the polyimide.

11. The light emitting diode assembly of claim 1, wherein the polyimide is additionally derived from no more than 50 mole percent of trans-1, 4-diaminocyclohexane, based on the total diamine content of the polyimide; 3, 5-diaminobenzotrifluoride; 2- (trifluoromethyl) -1, 4-phenylenediamine; 1, 3-diamino-2, 4,5, 6-tetrafluorobenzene; 2, 2-bis (3-aminophenyl) 1,1,1,3,3, 3-hexafluoropropane; 2,2' -bis- (4-aminophenyl) -hexafluoropropane (6F diamine); 3,4' -diaminodiphenyl ether (3,4' -ODA), m-phenylenediamine (MPD), 4, 4-bis (trifluoromethoxy) benzidine, 3,3' -diamino-5, 5' -trifluoromethylbiphenyl, 3,3' -diamino-6, 6' -trifluoromethylbiphenyl, 3,3' -bis (trifluoromethyl) benzidine; 2, 2-bis [4- (4-aminophenoxy) phenyl ] hexafluoropropane (4-BDAF),4,4 '-diaminodiphenyl sulfide (4,4' -DDS); 3,3 '-diaminodiphenyl sulfone (3,3' -DDS); 4,4' -diaminodiphenyl sulfone; 2,2' -bis (dimethyl) benzidine; 3,3' -bis (dimethyl) benzidine; 4,4 '-trifluoromethyl-2, 2' -diaminobiphenyl or mixtures thereof.

12. The light emitting diode assembly of claim 1, wherein the encapsulant is a silicone or an epoxy.

13. The light emitting diode assembly of claim 1, further comprising a solder mask consisting of:

14. A thermal control blanket comprising a filled polyimide layer; the filled polyimide layer is composed of:

wherein the thermal control blanket has a color L value of at least 85 as determined by ASTM E308[10 ° observer and illuminant D65] and a reflectance of at least 80% as determined according to ASTM E1164.

15. The thermal control blanket of claim 14 wherein the filled polyimide layer further comprises a sodium aluminum sulfosilicate pigment in an amount of 0.01 to 1 weight percent of the filled polyimide layer.

16. The thermal control blanket of claim 15 wherein the white pigment particulate filler is titanium dioxide.

17. The thermal control blanket of claim 14 wherein the polyimide is derived from 90 mole percent 3,3',4,4' -biphenyltetracarboxylic dianhydride and 100 mole percent 2,2' -bis (trifluoromethyl) benzidine and the white pigment particulate filler is titanium dioxide.

18. The thermal control blanket of claim 14 wherein the polyimide is derived from 100 mole percent 3,3',4,4' -biphenyltetracarboxylic dianhydride and 100 mole percent 2,2' -bis (trifluoromethyl) benzidine and the white pigment particulate filler is titanium dioxide.

19. The thermal control blanket of claim 14 wherein the polyimide is derived from at least 50 mole percent of 3,3',4,4' -biphenyltetracarboxylic dianhydride, based on the total dianhydride content of the polyimide.

20. The thermal control blanket of claim 14 wherein the polyimide is additionally derived from not more than 55 weight percent 4,4' -oxydiphthalic anhydride (ODPA); 4,4'- (4,4' -isopropylidenediphenoxy) bis (phthalic anhydride) (BPADA); 2,3,3',4' -biphenyltetracarboxylic dianhydride; 2,2',3,3' -biphenyltetracarboxylic dianhydride or a mixture thereof.

21. The thermal control blanket of claim 14 wherein the polyimide is additionally derived from not more than 55 weight percent of diphenylsulfone tetracarboxylic dianhydride (DSDA) based on the total dianhydride content of the polyimide; 4,4' -bisphenol a dianhydride; 1,2,3, 4-cyclobutanetetracarboxylic dianhydride; (-) - [1S, 5R, 6S ] -3-oxabicyclo [3.2.1] octane-2, 4-dione-6-spiro-3- (tetrahydrofuran-2, 5-dione) [ and bicyclo [2.2.2] oct-7-ene-2, 3,5, 6-tetracarboxylic dianhydride, 9, 9-disubstituted xanthene and mixtures thereof.

22. The thermal control blanket of claim 14 wherein the polyimide is additionally derived from not more than 55 weight percent 4,4' - (hexafluoroisopropylidene) phthalic anhydride (6FDA), based on the total dianhydride content of the polyimide.

23. The thermal control blanket of claim 14 wherein the polyimide is additionally derived from not more than 55 weight percent pyromellitic dianhydride, based on the total dianhydride content of the polyimide.

24. The thermal control blanket of claim 14 wherein the polyimide is additionally derived from no more than 50 mole percent of trans-1, 4-diaminocyclohexane; 3, 5-diaminobenzotrifluoride; 2- (trifluoromethyl) -1, 4-phenylenediamine; 1, 3-diamino-2, 4,5, 6-tetrafluorobenzene; 2, 2-bis (3-aminophenyl) 1,1,1,3,3, 3-hexafluoropropane; 2,2' -bis- (4-aminophenyl) -hexafluoropropane (6F diamine); 3,4' -diaminodiphenyl ether (3,4' -ODA), m-phenylenediamine (MPD), 4, 4-bis (trifluoromethoxy) benzidine, 3,3' -diamino-5, 5' -trifluoromethylbiphenyl, 3,3' -diamino-6, 6' -trifluoromethylbiphenyl, 3,3' -bis (trifluoromethyl) benzidine; 2, 2-bis [4- (4-aminophenoxy) phenyl ] hexafluoropropane (4-BDAF),4,4 '-diaminodiphenyl sulfide (4,4' -DDS); 3,3 '-diaminodiphenyl sulfone (3,3' -DDS); 4,4' -diaminodiphenyl sulfone; 2,2' -bis (dimethyl) benzidine; 3,3' -bis (dimethyl) benzidine; 4,4 '-trifluoromethyl-2, 2' -diaminobiphenyl and derivatives thereof.

25. The thermal control blanket of claim 14 wherein the electrically conductive filler is selected from the group consisting of carbon, metal particles, and mixtures thereof.

26. The thermal control blanket of claim 14 wherein the electrically conductive filler is selected from the group consisting of carbon black, graphite, and mixtures thereof.

27. The thermal control blanket of claim 14 further comprising an adhesive on at least one side of the thermal control blanket, wherein the adhesive is an epoxy adhesive, an acrylic adhesive, or a methacrylic adhesive.

28. The thermal control blanket of claim 14 further comprising a metal oxide adhesion promoter layer on at least one side of the thermal control blanket.