Material and method for preparing LED bracket by imprint lithography technology
Technical Field
The invention relates to an imprint lithography technology for manufacturing an LED bracket on a PCB or a pin in a large area and related materials. By the imprint lithography technology, the LED support from millimeter to micrometer scale can be prepared in situ in large area. By adopting the liquid imprinting adhesive, the LED bracket which has excellent curing property, good bonding property and excellent reliability can be realized quickly without waste materials.
Background
The traditional LED device mainly uses Thermoplastic Plastics (PPA), PA6T, PA9T, PCT and the like as resin materials, and due to the adoption of injection molding processing, repeated processing of flow channel materials causes long working procedures and performance deterioration, so that the LED device packaged by the Thermoplastic Plastics packaging bracket has the problems of poor heat dissipation, air tightness, heat resistance, light attenuation resistance and the like.
Although the LED bracket prepared by molding the Epoxy Molding Compound (EMC) is excellent in reliability test and use process, the LED bracket has the problems of material waste, high cost, complex process and the like.
The LED bracket prepared by the method needs to be further welded on a PCB after die bonding, wire bonding and packaging, and has the problems of long working procedure, serious waste of materials and energy and the like.
In recent years, with the development of small-pitch LED display and Chip Scale Package (CSP), LED holders are being miniaturized, and the demand for direct processing on a PCB board is increasing. The small-spacing LED prepared by the mould pressing method has the working procedures of mould pressing, cutting, welding and the like, and has the problems of material waste, complex working procedures, difficult welding, low reliability and the like.
Therefore, the preparation of the LED bracket has a series of problems of complex manufacturing process, material energy waste, low integration level, low reliability and the like.
On the other hand, the materials used for LED holders have mainly been concentrated on injection moldable thermoplastic resins, and thermosetting epoxy-based and silicone-based molding compounds. The problems of serious material and energy waste, difficult reliability guarantee and the like generally exist in the processing process.
Disclosure of Invention
In order to overcome the defects of the prior art and materials, the invention aims to provide an imprint lithography technology and a corresponding material technology, which can be used for manufacturing LED supports with different sizes in a large scale and simultaneously solve the problems of material energy consumption waste and reliability of support materials.
In order to achieve the purpose, the invention adopts the following technical scheme:
a method for preparing an LED bracket by an imprint lithography technology adopts imprint lithography equipment to coat and cure imprint glue on a Printed Circuit Board (PCB) or a pin. The imprint lithography apparatus includes a flexible composite mold a (1-4), a stage 8, and pneumatic, electric, vacuum, electrostatic systems. The stamping glue is a liquid or solid material and comprises resin, filler, functional auxiliary agent, photosensitive auxiliary agent and curing component.
The imprint lithography method comprises the following steps: the processes of die mounting, sample mounting, coating and imprinting of imprinting glue, photocuring (exposure), demolding, developing, post-curing and the like may be omitted.
And the die and the sample are installed, the flexible composite die A is adsorbed on the electric control mechanical arm through vacuum, and a pin to be processed or a PCB is installed on the sample bearing table 8.
The electric control mechanical hand can control vacuum adsorption and desorption by a program, and realizes the adsorption and desorption of the flexible composite mould from the middle or the side.
The coating of the stamping glue can coat the stamping glue on the pins or the PCB board by one or more methods of screen printing, ink jet, glue spraying, glue dispensing, hot calendaring technology, vacuum glue injection and the like.
The imprint lithography process, the coating of the imprint resist and the imprint process may be performed in steps or simultaneously. The imprinting process can adopt an electrostatic adsorption technology or a vacuum adsorption technology, a vacuum glue pouring technology at the same time, and a combination technology of the two technologies.
The electrostatic adsorption technical process comprises the following steps: adjusting the interval between the flexible composite mold and the sample coated with the imprinting glue to be 10-500 microns, applying a 220V-1000V electrostatic field between the sample and the flexible composite mold, releasing vacuum adsorption from the middle to four sides by an electric control manipulator according to a program, completely filling the mold with the liquid imprinting glue from the middle under the action of electrostatic attraction, and simultaneously tightly attaching the flexible composite mold to the surface of the sample to avoid generating bubbles and form imprinting glue patterning without gap and glue leakage.
The vacuum adsorption process comprises the following steps: the flexible composite mold and the sample coated with the imprinting glue are gradually jointed from one side edge and loaded with a vacuum system under the action of an electric control manipulator, liquid imprinting glue completely fills the mold from one side edge under the action of negative pressure, and the flexible composite mold is gradually attached to the surface of the sample to form the imprinting glue patterning without gap leakage.
The vacuum adsorption glue injection process comprises the following steps: the flexible composite mold is attached to a sample under the action of an electric control mechanical arm, a vacuum system is loaded, liquid imprinting glue is injected from one side edge to the mold which is completely filled in a vacuum glue injection mode, and the imprinting glue imaging without gap leakage is formed.
The photo-curing technology of the imprinting adhesive selects ultraviolet and visible light sensitive photo-curing imprinting adhesive and cures under illumination. The light exposure time may vary from 10 seconds to 5 minutes depending on the imprint gel used.
In the demolding process of the imprinting glue, the electric control mechanical hand starts vacuum adsorption on the flexible composite mold from one side, so that the flexible composite mold is gradually separated from the solidified imprinting glue, and the demolding difficulty is avoided.
In the developing process of the stamping glue, residual uncured stamping glue is cleaned by using a solvent, such as one or more of acetone, dimethyl carbonate, ethanol, an alkaline aqueous solution and the like.
In the post-curing process of the stamping glue, the complete curing of the stamping glue is realized by utilizing the technologies such as heating, infrared rays or microwaves and the like.
The flexible composite die comprises four layers, namely a transparent backing layer 1, a transparent conducting layer 2, a transparent functional layer 3, an ultraviolet reflecting (absorbing) layer 4 and the like.
The transparent back lining layer of the flexible composite mould is made of organic glass (PMMA), polycarbonate, polyester, optical glass, quartz glass, sapphire and the like.
The transparent conducting layer of the flexible composite mould is made of polymer conducting materials compounded by Indium Tin Oxide (ITO), doped tin dioxide (FTO), nano metal or conducting fillers.
The transparent functional layer of the flexible composite mold adopts hard Polydimethylsiloxane (PDMS), hydrophobic modified transparent epoxy resin, hydrophobic modified cross-linking type transparent acrylate material and transparent fluorine-containing material.
The ultraviolet reflecting (absorbing) layer of the flexible composite die adopts a metal coating layer subjected to hydrophobic treatment, hard polydimethylsiloxane mixed with silver, nickel, carbon powder, graphite powder and the like, fluorine-containing high polymer materials and the like.
The stamping glue is formed by matching one or more of epoxy resin, acrylic ester, polyurethane, vinyl ester resin, vinyl ether resin and the like with a functional material.
The epoxy resin is one or more of aliphatic, aromatic and heteroatom-containing epoxy resin. Including, but not limited to, one or more of bis (3, 4-epoxycyclohexylmethyl) adipic acid, hydrogenated bisphenol a glycidyl ether, hexahydrophthalic anhydride glycidyl ester, phthalic anhydride glycidyl ester, trimellitic triglycidyl ester, triglycidyl isocyanate, bisphenol a glycidyl ether, bisphenol F glycidyl ether, bisphenol S glycidyl ether, o-cresol epoxy resin, and the like.
The acrylate is one or more of monofunctional group, bifunctional group and polyfunctional group. Including, but not limited to, tricyclo [5.2.1.02,6] decane dimethanol acrylate, glycidyl methacrylate, isobornyl methacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol dimethacrylate, polypropylene glycol diacrylate, polypropylene glycol dimethacrylate, butanediol diacrylate, butanediol dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, 1, 4-butanediol diacrylate, 1, 6-hexanediol dimethacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, trimethylolpropane trimethacrylate acrylate polyester, and mixtures thereof, One or more of acrylic polyurethane, acrylic epoxy resin, acrylic polyether resin and the like
The polyurethane is aliphatic or aromatic polymer containing polyester and polyether structures and contains hydroxyl, acrylate groups or isocyanate groups.
The functional material comprises reflectors, coloring matters, reinforcements, interface treatment agents, ion adsorbents, photoinitiators, light stabilizers, anti-aging agents and release agents.
The reflector includes, but is not limited to, one or more of titanium oxide, zirconium oxide, zinc oxide, aluminum oxide, and the like.
The reinforcement includes, but is not limited to, one or more of quartz powder, silica micropowder, amorphous silica micropowder, spherical silica micropowder, calcium carbonate, glass fiber, mineral fiber, talcum powder, mica powder, clay and the like.
The interface treating agent includes, but is not limited to, one or more of organic siloxane, organic titanium, organic chromium and the like.
The photoinitiator includes, but is not limited to, benzoin and derivatives thereof, acetophenone derivatives, aromatic ketones, polyene-thiols, thioxanthone, alkyl metals, metal carbonyls, cationic photoinitiators.
Drawings
Fig. 1 is a flowchart of the present embodiment.
Detailed Description
The present invention will be described in detail with reference to the following examples, but the present invention is not limited to the following examples.
Referring to fig. 1, a method for manufacturing an LED support by an imprint lithography technique, which applies an imprint lithography apparatus to coat and cure an imprint resist on a Printed Circuit Board (PCB) or a lead. The imprint lithography apparatus includes a flexible composite mold a (1-4), a stage 8, and a pneumatic, motorized, vacuum, electrostatic system. The stamping glue is a liquid or solid material and comprises resin, filler, functional auxiliary agent, photosensitive auxiliary agent and curing component.
The flexible composite mould A is adsorbed on the electric control mechanical arm through vacuum; the pins or PCB boards to be processed are mounted on the sample holder 8.
The stamping glue is coated on the pins or the PCB board by one or more methods of screen printing, ink jetting, glue spraying, glue dispensing, hot calendaring technology, vacuum glue injection and the like.
The interval between the flexible composite mold and the sample coated with the imprinting glue is adjusted to be 10-500 micrometers, a 500V electrostatic field is applied between the sample and the flexible composite mold, an electric control mechanical arm capable of controlling vacuum adsorption and desorption in a program mode is adopted, vacuum adsorption of the flexible composite mold from the middle to four sides is released, liquid imprinting glue completely fills the mold from the middle under the action of electrostatic attraction force, the flexible composite mold is tightly attached to the surface of the sample at the same time, bubbles are avoided being generated, and imprinting glue imaging without gap and glue leakage is formed.
Selecting photosensitive photocuring imprinting glue, and curing under the irradiation of a 365nm ultraviolet lamp and the irradiation illumination of 7000mW/cm 2. The illumination time depends on the embossing paste used, and is shown below in the following example of the embossing paste.
After photocuring is finished, the demolding process of the imprinting glue is started, the electric control mechanical hand starts vacuum adsorption on the flexible composite mold from one side, so that the flexible composite mold is gradually separated from the solidified imprinting glue, and the demolding difficulty is avoided.
And (3) demolding the LED support, and cleaning the residual uncured stamping glue by using one or more solvents such as acetone, dimethyl carbonate, ethanol, alkaline aqueous solution and the like under the action of ultrasonic waves.
And (3) curing at 150 ℃ by using the technologies of heating, infrared rays or microwaves and the like to realize the complete curing of the imprinting adhesive.
In the present embodiment, the flexible composite mold comprises four layers, i.e., a transparent backing layer 1, a transparent conductive layer 2, a transparent functional layer 3, and an ultraviolet reflective (absorbing) layer 4.
The transparent back lining layer of the flexible composite mould is made of organic glass (PMMA), polycarbonate, polyester, optical glass, quartz glass, sapphire and the like.
The transparent conducting layer of the flexible composite mould is made of polymer conducting materials compounded by Indium Tin Oxide (ITO), doped tin dioxide (FTO), nano metal or conducting fillers.
The transparent functional layer of the flexible composite mold adopts hard Polydimethylsiloxane (PDMS), hydrophobic modified transparent epoxy resin, hydrophobic modified cross-linking type transparent acrylate material and transparent fluorine-containing material.
The ultraviolet reflecting (absorbing) layer of the flexible composite die adopts a metal coating layer subjected to hydrophobic treatment, hard polydimethylsiloxane mixed with silver, nickel, carbon powder, graphite powder and the like, fluorine-containing high polymer materials and the like.
The imprinting adhesive used was selected from a variety of materials, and the materials used in the following examples were as follows.
Alicyclic epoxy resin (ERL-4221: Dow chemical trade name, epoxy equivalent 128 to 140)
Phenol type epoxy resin (DEN 438: Dow chemical trade name, epoxy equivalent 183 to 193)
Alicyclic epoxy resin (EHPE 3150: Nippon Daolute trade name, epoxy equivalent 177)
Bisphenol A type epoxy resin (DER 332: Dow chemical trade name, epoxy equivalent 172 to 176)
Tertiary carboxylic acid glycidyl ester (Cardura E10P: American Mei Tu trade name)
Triallyl isocyanurate (TAIC: trade name of Nippon Kabushiki Kaisha)
Mercaptan (TEMPIC: Sakai chemical trade name)
Glycidyl Methacrylate (GMA)
Isobornyl methacrylate (SR 423: Sartomer trade name)
1, 6-hexanediol diacrylate (SR 238: Sartomer trade name)
Dicyclodecane dimethanol diacrylate (SR 833S: Sartomer trade name)
Tris (2-hydroxyethyl) isocyanuric acid triacrylate (SR 368D: Sartomer trade name)
Urethane acrylate (CN 981: Sartomer trade name)
Epoxy acrylate (CN 104: Sartomer trade name)
Polyester acrylate oligomer (CN 750: Sartomer trade name)
2-Isopropylthioxanthone (Omnirad ITX: IGM trade name)
4-Isobutylphenyl-4' -methylphenyliodohexafluorophosphate (Omnirad 250: IGM trade name)
3-glycidoxypropyltrimethoxysilane (GLYMO: Desmoset trade name)
3-Methacryloxypropyltrimethoxysilane (MEMO: Desmosai trade name)
Antioxidant Revonox 501, Taiwan Chiitanium science and technology trade name
Antioxidant 1010, under the tradename of Basff
Light stabilizer 622, tradename of Basff
Trade name of SI-100L, Japan trinitrotoluene chemical
Various measurements in examples were carried out by the following methods
(1) Heat resistance
The prepared LED mount was aged at 150 ℃ for 200 hours, and the appearance of the aged cured product was visually observed to evaluate the heat resistance by the following criteria.
(color change)
A is not changed
B: slightly changed
C: yellowing occurs
(2) Light resistance
The prepared LED holder was irradiated with a point light source of 350nm or less, and irradiated with ultraviolet light at an illuminance of 5000mW/cm2 for 200 hours, and the appearance of the cured product after ultraviolet irradiation was visually observed, and the light resistance was evaluated by the following criteria.
(color change)
A is not changed
B: slightly changed
C: yellowing occurs
(3) Moisture absorption and peeling resistance after reflow soldering
The prepared LED support is placed in a constant temperature and humidity box with the humidity of 85 ℃/85% for 12 hours and 36 hours, and a reflow soldering procedure with the highest temperature of 260 ℃ for 10 seconds is carried out for 3 times by using a reflow soldering device. And observing the interface peeling of the LED bracket after reflow soldering by using an optical microscope. The same observation was made for each 20 samples, and the peeling resistance was evaluated by the following criteria.
AA, no peeling after standing for 36 hours
A, no peeling after 12 hours of standing, peeling after 36 hours of standing
B: after 12 hours of placement, 1-5 packages are peeled from the resin in 20 packages
C: after 12 hours of placement, more than 6 packages in 20 packages are peeled off from the resin
(4) Resistance to thermal shock
And (3) heating the prepared LED bracket from-65 ℃ to 150 ℃ at the speed of 1 ℃/min, and cooling the prepared LED bracket from 150 ℃ to-65 ℃, wherein the temperature is 1 cycle, and performing 1000 cycles of cold and hot shock. And after the experiment is finished, observing the interface stripping of the LED support after reflow soldering by using an optical microscope. The same observation was made for each 20 samples, and the thermal shock resistance was evaluated by the following criteria.
A: without peeling
B: 20 packages with 1-5 packages are peeled off from the resin
C: more than 6 packages in 20 packages are peeled off from the resin
The sequence of the above embodiments is only for convenience of description and does not represent the advantages and disadvantages of the embodiments.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.