1. A thixotropic light-cured circuit board protective resin capable of being self-peeled after being expanded is characterized by comprising the following components in parts by weight: 30-50% of acrylate oligomer

6.5 to 48.9 percent of diluent

10 to 20 percent of expanded microspheres

1 to 3 percent of free radical initiator

0.1 to 0.5 percent of flatting agent

10-20% of thixotropic thickening agent; the expanded microspheres have a heated expansion temperature of 85-105 ℃ and at this temperature the expanded microspheres expand only without breaking.

2. The self-releasing thixotropic light-curable circuit board protective resin after expansion of claim 1, wherein the acrylic oligomer is at least one of urethane acrylate, pure acrylate, polyester acrylate, and epoxy acrylate.

3. The self-releasing thixotropic light-curable circuit board protective resin after expansion of claim 1, wherein the diluent is one or more of acryloyl morpholine, polyethylene glycol (400) diacrylate, trimethylolpropane triacrylate, ethoxylated pentaerythritol tetraacrylate, tripropylene glycol diacrylate, dipentaerythritol hexaacrylate, and hydroxyethyl methacrylate.

4. The thixotropic light-curable circuit board protective resin capable of being peeled off after expansion of claim 1, wherein the expanded microspheres are at least one of HF-48D, F-35D from Songyou pharmaceutical Co., Ltd or UM110a from Santa Clara chemical industry.

5. The self-stripping thixotropic photocurable circuit board protective resin after expansion of claim 1, wherein the radical initiator is one or more of ultraviolet initiators 907, 1173, 184, TPO, ITX.

6. The thixotropic light-curable circuit board protective resin that self-peels off after expansion of claim 1, wherein the leveling agent is at least one of 333, 300, 331 of BYK, germany.

7. The self-stripping after expansion thixotropic light-cured circuit board protective resin of claim 1, wherein the thixotropic thickener is at least one of organobentonite, fumed silica, and hydroxypropyl cellulose.

8. Use of the thixotropic light-curable circuit board protective resin that self-peels off after expansion according to any one of claims 1 to 7, wherein: the method comprises the following steps: firstly, the thixotropic light-cured circuit board protective resin capable of being automatically peeled off after expansion is dispensed on a position needing to be protected on a circuit board through a dispenser, after ultraviolet or visible light irradiation curing, the circuit board integrally enters a post-treatment process to form a packaging protective film layer, after the post-treatment process of the circuit board is finished, the circuit board integrally is baked at the temperature of 85-105 ℃ for 0.5-5 minutes to ensure that the thixotropic light-cured circuit board protective resin capable of being automatically peeled off after expansion is expanded, the rough surface deformation formed by expansion can be automatically and primarily peeled off from the surface of the circuit board, and then the primarily peeled protective resin is thoroughly removed from the circuit board through air gun blowing.

Background

The consumer electronics market and advanced application scenes have higher and higher requirements on various performances of electronic circuit boards, wherein the three-prevention requirements of mold prevention, moisture prevention and salt mist prevention almost become the basic requirements of modern circuit boards. The three-proofing of the circuit board is realized mainly by depending on a circuit board coating technology and other circuit board post-processing technologies, and particularly the post-processing of a semi-finished circuit board is very important. The semi-finished circuit board is generally packaged and protected by methods such as spraying, ion sputtering, chemical deposition and the like, and the post-treatment processes can cover a protective layer on the surface of the circuit board to play roles of insulation, sealing, dewatering, self-cleaning and the like. The circuit board generally cannot work independently, other circuits or external equipment, sensors, loads and the like need to be connected, the positions of the connections need to be conductive and stable, and the connection obviously conflicts with the three-proofing requirement of the circuit board body, that is, the conductivity of the conductive part of the circuit board cannot be damaged in the post-processing process, and the protection of the part needing to be protected is sufficient. In order to meet the requirement of selective conductivity retention, the position to be protected is protected in advance by the traditional circuit board processing technology before processing, generally, curable protective resin is coated on the position to be protected by adopting a glue dispensing or gluing technology, then the protective resin is cured by means of heat or illumination, and the protective layer cured on the position to be protected is removed by technical means after the protected circuit board is subjected to post-processing. In the prior art, the glue dispensing, coating and post-treatment means can be conveniently controlled automatically by technical means, but the cured protective layer has the characteristics of high strength, strong adhesive force, thin thickness and the like, some protective layers even penetrate into the rear part of a metal sheet at a conductive position to be difficult to peel off, the automatic peeling is controlled by machine vision, and a plurality of treatment manufacturers can only treat the protective layers by a manual peeling method. In order to solve the pain which troubles the protection of the circuit board, the invention provides the expandable light-cured circuit board protective resin, which adopts a method of first curing and then expanding to realize that the circuit board protective resin can be easily peeled or blown off from the circuit board only by simple low-temperature baking after the completion of the service of the processing process of protecting the circuit board.

In the existing patent, the research of preparing the circuit board protective resin by photocuring is many, because the photocuring technology has the characteristics of high curing speed, high production efficiency, suitability for flow line production, no solvent discharge, no need of forced heating for curing, low curing energy consumption and energy conservation. However, the cured material has the characteristics of high strength, strong adhesion, thin thickness and the like, but the resin has high viscosity and is easy to permeate into the rear part of the metal sheet at the conductive position, so that the metal sheet is difficult to peel off, and the subsequent treatment operation is complicated. Publication No.: CN1699492A discloses a photo-curing conductive adhesive and a preparation method thereof, and the resin has good adhesiveness and solvent resistance after being cured; the adhesive has high bonding strength and low resistivity, can meet the requirements of microelectronic packaging technologies such as polyester, thin film circuits, PCB (printed circuit board) and the like, but has complex research and preparation processes and has strict requirements on the content of raw materials. Publication No.: the invention patent of CN106977658A discloses a 3D printing light-cured resin and a preparation method thereof, the resin prepared by the method has high light sensitivity and high forming speed, and can improve the processing efficiency of 3D printing, but the viscosity of the material can be increased after the material is stored for a long time, the material is easy to deteriorate, and the storage performance of equipment can be influenced. Publication No.: the invention patent of CN110499130A discloses a visible light curing adhesive and a preparation method thereof, the prepared adhesive has the advantages of low surface tension, fast curing speed, small shrinkage, strong bonding force and simple preparation method, but moisture can enter the circuit board to cause hydration of polar epoxy adhesive, thereby weakening and reducing chemical bonding of the interface, and finally making the packaging interface fail. The performance of circuit board protective materials is a key to determining whether a material is suitable for a particular packaging technology, packaging design, manufacturing process, and electronic application, and is the basis for circuit board reliability determinations. The traditional circuit board post-processing method comprises the steps of manually placing a PCB optical plate on a belt conveyor to be sent to a two-stage crusher to be crushed into particles, and then separating and recycling copper and nonmetal in the PCB through three-stage grinding, wind classification, gravity classification, screening classification, high-voltage electrostatic separator separation and other links. The method is complex to operate and high in separation process difficulty, so that the method changes the self performance of the material, simplifies the treatment process and improves the recovery and utilization rate of resources.

Disclosure of Invention

In order to overcome the problems in the prior art, the invention provides thixotropic light-cured circuit board protective resin capable of being expanded and then automatically stripped, which is suitable for pipeline conveying and coating of a dispenser, cannot permeate into the bottom of a metal elastic sheet, cannot pollute the peripheral area, and can enable the expanded surface of the protective resin to be rough after baking by adopting a method of firstly curing and then expanding, so that the protective resin can easily fall off, the processing steps are simplified, and corresponding resources are saved.

In order to realize the purpose of the invention, the adopted technical scheme is as follows: the thixotropic light-cured circuit board protective resin capable of being self-stripped after being expanded comprises the following components in parts by weight:

30-50% of acrylate oligomer

6.5 to 48.9 percent of diluent

10 to 20 percent of expanded microspheres

1 to 3 percent of free radical initiator

0.1 to 0.5 percent of flatting agent

10-20% of thixotropic thickening agent; the expanded microspheres have a heated expansion temperature of 85-105 ℃ and at this temperature the expanded microspheres expand only without breaking. In the post-treatment process, a packaging protection film is formed on the surface of the circuit board and used for ensuring the performances of insulation, moisture resistance, salt mist resistance and the like, however, if the expansion temperature is too high, the performances of insulation, moisture resistance and the like of the packaging protection film are reduced, even the edge of the packaging protection film is curled, therefore, the expansion temperature cannot be too high, 105 ℃ is the limit temperature which can be borne by the packaging film, and the optimal expansion temperature is controlled to be 85-100 ℃.

Preferably, the acrylic oligomer is at least one of urethane acrylate, pure acrylate, polyester acrylate and epoxy acrylate.

Preferably, the diluent is one or more of acryloyl morpholine, polyethylene glycol (400) diacrylate, trimethylolpropane triacrylate, ethoxylated pentaerythritol tetraacrylate, tripropylene glycol diacrylate, dipentaerythritol hexaacrylate, and hydroxyethyl methacrylate.

Preferably, the expanded microspheres are at least one of HF-48D, F-35D from Songyou lipid pharmaceuticals, or UM110a from Santa Clara and Chemicals.

Preferably, the free radical initiator is one or more of ultraviolet initiators 907, 1173, 184, TPO, ITX.

Preferably, the leveling agent is at least one of 333, 300 and 331 of Germany BYK.

Preferably, the thixotropic thickener is at least one of organic bentonite, fumed silica and hydroxypropyl cellulose.

The application of the thixotropic light-cured circuit board protective resin capable of being automatically peeled off after being expanded comprises the following steps: firstly, the thixotropic light-cured circuit board protective resin capable of being expanded and automatically stripped is dispensed on a position needing to be protected on a circuit board through a dispenser, after ultraviolet or visible light irradiation curing, the circuit board integrally enters a post-treatment process to form a packaging protective film layer, and in the post-treatment process, the position coated with the expandable stripped light-cured circuit board protective resin on the circuit board is protected, so that the performances of conductivity or light transmission and the like cannot be influenced by the post-treatment process. After the post-treatment process of the circuit board is finished, the whole is baked for 0.5-5 minutes at the temperature of 85-105 ℃, so that the thixotropic photocuring circuit board protective resin which can be automatically stripped after expansion expands, rough surface deformation formed by expansion can be automatically and primarily stripped from the surface of the circuit board, and then the protective resin which is primarily stripped is thoroughly removed from the circuit board by blowing through an air gun.

The application method comprises the steps that firstly, the expandable light-cured circuit board protective resin is coated on the position, needing to be protected, of the circuit board in a dispensing machine in a dispensing mode, after ultraviolet or visible light irradiation curing, the circuit board integrally enters a post-processing procedure, the position, coated with the expandable light-cured circuit board protective resin, of the circuit board in the post-processing procedure is protected, and the performances of conductivity or light transmission and the like cannot be influenced by the post-processing procedure. After the post-treatment process of the circuit board is finished, the whole circuit board is baked for a specific time at a specific temperature, so that the coated expandable light-cured circuit board protective resin expands like popcorn, the rough surface formed by expansion can be automatically stripped from the protected surface, and the stripping can be conveniently carried out by adopting simple methods such as air gun blowing and the like.

Compared with the prior art, the invention has the following beneficial effects: the thixotropic photocuring circuit board protective resin capable of being automatically peeled off after expansion has the characteristics of thixotropy, photocuring property and expandability, can protect a specific position on a circuit board in the circuit board post-treatment process, cannot flow randomly, prevents the insulation post-treatment from influencing the electric conduction of the wiring part of the circuit board, expands like popcorn through a baking method after the post-treatment process, and automatically peels off the protected surface due to the rough surface deformation formed by expansion, so that the peeling can be conveniently carried out only by adopting simple methods such as air gun blowing and the like, meanwhile, the overall process cannot influence the insulation, moisture resistance, salt fog resistance and other properties of a packaging protective film, and the yield cannot be reduced due to the peeling of a photocuring layer. In order to realize the use of the expanded microspheres, the fluidity of the resin needs to be enhanced, the resin flows on a circuit board after dispensing, so that the dispensing process is difficult to control, and the use of the thixotropic thickening agent can overcome the negative influence caused by high fluidity, thereby not only ensuring the operability of resin dispensing, but also ensuring the controllability of the resin in the presence of a large amount of microspheres.

Drawings

FIG. 1 is a flow chart illustrating the method of using a thixotropic light-curable circuit board protective resin that self-peels off after swelling in an embodiment of the present invention.

Detailed Description

The present invention is further illustrated by the following examples, but the scope of the present invention is not limited to the following examples.

Example 1

The formula of the thixotropic light-cured circuit board protective resin capable of being self-stripped after being expanded is as follows,

acrylic acid oligomer: 30 percent of polyurethane acrylate

Diluent 1: polyethylene glycol (400) diacrylate 25%

Diluent 2: ethoxylated pentaerythritol tetraacrylate 23.9%

Expanded microspheres: HF-48D 10% of Songban oil pharmaceutical Co., Ltd

Free radical initiator: 11731 percent

Leveling agent: BYK 3330.1%

Thixotropic thickeners: 10 percent of organic bentonite.

The preparation and use method of the expandable light-cured circuit board protective resin for preventing the insulation post-treatment from influencing the conduction of the wiring part of the circuit board comprises the following steps: the components in the formula are fully and uniformly mixed and then put into a glue bottle for standby. And setting the dispensing amount of each protected position on an automatic dispenser according to 0.2g per square millimeter for dispensing and coating, and curing the circuit board coated with the glue for 10 seconds under the ultraviolet light with the wavelength of 365nm and 35 w. And (3) putting the cured and protected circuit board into a vapor chemical deposition furnace, and depositing a three-proofing protective layer on the surface of the circuit board by a vapor chemical deposition method. And (3) baking the circuit board deposited with the three-proofing protection layer at 105 ℃ for 60 seconds through a baking channel to ensure that the adhesive-dispensed expandable light-cured circuit board protective resin is fully expanded, and after the baked circuit board passes through three high-pressure gas air curtains arranged in different directions, finishing the stripping process of the expanded light-cured circuit board protective resin at the protective position to obtain the finished circuit board with three-proofing surface treatment.

Example 2

The formula of the thixotropic light-cured circuit board protective resin capable of being automatically peeled off after being expanded is as follows:

acrylic acid oligomer: 15% of polyester acrylate; 15 percent of pure acrylic ester

Diluent 1: acryloyl morpholine 10%

Diluent 2: ethoxylated pentaerythritol tetraacrylate 6.5%

Diluent 3: 10 percent of trimethylolpropane triacrylate

Expanded microspheres: F-35D 20% of Songban oil pharmaceutical Co., Ltd

Free radical initiator: 11731.5 percent; 9071.5 percent

Leveling agent: BYK 3000.5%

Thixotropic thickener 1: fumed silica 10%

Thixotropic thickener 2: 10 percent of hydroxypropyl cellulose.

The preparation and use method of the expandable light-cured circuit board protective resin for preventing the insulation post-treatment from influencing the conduction of the wiring part of the circuit board comprises the following steps: the components in the formula are fully and uniformly mixed and then put into a glue bottle for standby. And setting the dispensing amount of each protected position on an automatic dispenser according to 0.2g per square millimeter for dispensing and coating, and curing the circuit board coated with the glue for 10 seconds under the ultraviolet light with the wavelength of 365nm and 35 w. And (3) putting the cured and protected circuit board into a vapor chemical deposition furnace, and depositing a three-proofing protective layer on the surface of the circuit board by a vapor chemical deposition method. And (3) baking the circuit board deposited with the three-proofing protection layer at 105 ℃ for 60 seconds through a baking channel to ensure that the adhesive-dispensed expandable light-cured circuit board protective resin is fully expanded, and after the baked circuit board passes through three high-pressure gas air curtains arranged in different directions, finishing the stripping process of the expanded light-cured circuit board protective resin at the protective position to obtain the finished circuit board with three-proofing surface treatment.

Example 3

The formula of the thixotropic light-cured circuit board protective resin capable of being automatically peeled off after being expanded is as follows:

acrylic acid oligomer: 30% of polyester acrylate; 10% of epoxy acrylate; 10 percent of urethane acrylate

Diluent agent: tripropylene glycol diacrylate 6.5%

Expanded microspheres: HF-48D 10% of Songban oil pharmaceutical Co., Ltd; sansheng and chemical UM110a 10%

Free radical initiator: 11731 percent; 1841%; TPO 1%

Leveling agent: BYK 3310.3%; BYK 3000.2%

Thixotropic thickeners: 20% of fumed silica.

The preparation and use method of the expandable light-cured circuit board protective resin for preventing the insulation post-treatment from influencing the conduction of the wiring part of the circuit board comprises the following steps: the components in the formula are fully and uniformly mixed and then put into a glue bottle for standby. And setting the dispensing amount of each protected position on an automatic dispenser according to 0.2g per square millimeter for dispensing and coating, and curing the circuit board coated with the glue for 10 seconds under the ultraviolet light with the wavelength of 365nm and 35 w. And (3) putting the cured and protected circuit board into a vapor chemical deposition furnace, and depositing a three-proofing protective layer on the surface of the circuit board by a vapor chemical deposition method. And (3) baking the circuit board deposited with the three-proofing protection layer at 85 ℃ for 60 seconds through a baking channel to ensure that the protective resin of the adhesive-dispensed expandable photocuring circuit board is fully expanded, and peeling off the protective resin of the expanded photocuring circuit board at the protection position after the baked circuit board passes through three high-pressure gas air curtains arranged in different directions to obtain the finished circuit board with the three-proofing surface treatment.

Example 4

The formula of the thixotropic light-cured circuit board protective resin capable of being automatically peeled off after being expanded is as follows:

acrylic acid oligomer: 10% of urethane acrylate; 10 percent of epoxy acrylate

Diluent 1: polyethylene glycol (400) diacrylate 5%

Diluent 2: ethoxylated pentaerythritol tetraacrylate 8.9%

Diluent 3: acryloyl morpholine 5%

Diluent 4: trimethylolpropane triacrylate 5%

Diluent 5: tripropylene glycol diacrylate 6%

Diluent 6: 15 percent of dipentaerythritol hexaacrylate

Diluent 7: 4 percent of hydroxyethyl methacrylate

Expanded microspheres: HF-48D 10% of Songban oil pharmaceutical Co., Ltd; F-35D 10%

Free radical initiator: 11730.25 percent; 9070.25 percent; 1840.25 percent; ITX 0.25%

Leveling agent: BYK 3330.03%; BYK 3310.07%

Thixotropic thickeners: 10 percent of hydroxypropyl cellulose.

The preparation and use method of the expandable light-cured circuit board protective resin for preventing the insulation post-treatment from influencing the conduction of the wiring part of the circuit board comprises the following steps: the components in the formula are fully and uniformly mixed and then put into a glue bottle for standby. And setting the dispensing amount of each protected position on an automatic dispenser according to 0.2g per square millimeter for dispensing and coating, and curing the circuit board coated with the glue for 10 seconds under the ultraviolet light with the wavelength of 365nm and 35 w. And (3) putting the cured and protected circuit board into a vapor chemical deposition furnace, and depositing a three-proofing protective layer on the surface of the circuit board by a vapor chemical deposition method. And (3) baking the circuit board deposited with the three-proofing protection layer at 95 ℃ for 60 seconds through a baking channel to ensure that the protective resin of the adhesive-dispensed expandable photocuring circuit board is fully expanded, and peeling off the protective resin of the expanded photocuring circuit board at the protection position after the baked circuit board passes through three high-pressure gas air curtains arranged in different directions to obtain the finished circuit board with the three-proofing surface treatment.

Example 5

The formula of the thixotropic light-cured circuit board protective resin capable of being automatically peeled off after being expanded is as follows:

acrylic acid oligomer: 10% of urethane acrylate; 10% of pure acrylate; 10% of polyester acrylate; 10 percent of epoxy acrylate

Diluent 1: polyethylene glycol (400) diacrylate 5%

Diluent 2: tripropylene glycol diacrylate 5%

Diluent 3: 5 percent of dipentaerythritol hexaacrylate

Diluent 4: hydroxyethyl methacrylate 5%

Diluent 5: trimethylolpropane triacrylate 6.5%

Expanded microspheres: HF-48D 10% of Songban oil pharmaceutical Co., Ltd; F-35D 5%; sansheng and chemical UM110a 5%

Free radical initiator: 11731 percent; 9070.5 percent; 1840.5 percent; TPO 0.5%; ITX 0.5%

Leveling agent: BYK 3330.1%; BYK 3000.2%; BYK 3310.2%

Thixotropic thickener 1: fumed silica 5%

Thixotropic thickener 2: 5 percent of hydroxypropyl cellulose.

The preparation and use method of the expandable light-cured circuit board protective resin for preventing the insulation post-treatment from influencing the conduction of the wiring part of the circuit board comprises the following steps: the components in the formula are fully and uniformly mixed and then put into a glue bottle for standby. And setting the dispensing amount of each protected position on an automatic dispenser according to 0.2g per square millimeter for dispensing and coating, and curing the circuit board coated with the glue for 10 seconds under the ultraviolet light with the wavelength of 365nm and 35 w. And (3) putting the cured and protected circuit board into a vapor chemical deposition furnace, and depositing a three-proofing protective layer on the surface of the circuit board by a vapor chemical deposition method. And (3) baking the circuit board deposited with the three-proofing protection layer at 105 ℃ for 60 seconds through a baking channel to ensure that the adhesive-dispensed expandable light-cured circuit board protective resin is fully expanded, and after the baked circuit board passes through three high-pressure gas air curtains arranged in different directions, finishing the stripping process of the expanded light-cured circuit board protective resin at the protective position to obtain the finished circuit board with three-proofing surface treatment.

TABLE 1 protective Properties of the different examples

The above table shows the embodiment and the circuit board which is not subjected to coating protection and traditional resin protection after post-treatment, and it can be seen that the embodiment of the invention not only can protect the conductivity of the circuit board from being damaged in the post-treatment process, but also the expandable light-cured circuit board protection resin expands like popcorn after the circuit board is integrally baked at a specific temperature for a specific time after the post-treatment process is finished, and the rough surface deformation formed by the expansion can automatically peel off the protected surface, so that the peeling can be conveniently performed only by adopting simple methods such as air gun blowing and the like. The post-treatment time such as stripping is greatly shortened, the defective rate is greatly improved compared with the conventional agreement, and the method is a technology with popularization prospect in the protection of electronic circuit boards in the future.