Coating and curing method and coating and curing system for circuit board

Abstract

The invention provides a coating and curing method and system of a circuit board, the circuit board is provided with a first surface and a second surface which are arranged oppositely, and the coating and curing method comprises the following steps: carrying out paint film coating treatment on the first surface; carrying out pre-curing treatment on the first surface; carrying out board turning treatment on the circuit board; the second surface is subjected to paint film coating treatment; and performing final curing treatment on the first surface and the second surface. According to the application, the risk of paint liquid sagging of a paint film coated on the first surface due to plate turning can be reduced, and the coating effect is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of circuit board, in particular to a coating and curing method and system for circuit board. BACKGROUND

[0002] As the core functional carrier of mobile phones, home appliances and other electronic devices, the reliability of the circuit board directly affects the stability and service life of the electronic device. However, the circuit board often faces complex environmental challenges in practical application, such as high temperature and humidity, dust pollution, chemical corrosion (such as acid and alkali gas), mechanical vibration, etc. These factors may cause oxidation of solder joints, metal migration, reduction of insulation performance, and even circuit short circuit, thereby causing device failure.

[0003] In order to improve the protection ability of the circuit board, a functional protective coating can be coated on the surface of the circuit board, such as coating a three-proofing paint to form a paint film. The three-proofing paint needs to be cured after coating to realize the transformation of the coating from liquid to solid, thereby forming a stable protective structure. Usually, the double sides of the circuit board need to be coated with paint film, but the problem of paint liquid flowing may occur, which affects the coating effect. SUMMARY

[0004] The present application provides a coating and curing method and system for circuit board, which can reduce the risk of paint liquid flowing during double-sided coating and improve the coating effect.

[0005] To solve the above technical problems, the present application provides a coating and curing method for circuit board, the circuit board has a first surface and a second surface arranged opposite to each other, the coating and curing method comprising: coating a paint film on the first surface; pre-curing the first surface; turning the circuit board; coating a paint film on the second surface; and finally curing the first surface and the second surface.

[0006] To solve the above technical problems, the present application further provides a coating and curing system. The coating and curing system is used for circuit board, the circuit board has a first surface and a second surface arranged opposite to each other, the coating and curing system comprises a coating and pre-curing device and a final curing device, the coating and pre-curing device is used for sequentially coating a paint film on the first surface, pre-curing the first surface, turning the circuit board, and coating a paint film on the second surface; and the final curing device is used for finally curing the first surface and the second surface.

[0007] The beneficial effects of the present application are: the coating and curing method of the present application comprises: performing a paint film coating treatment on the first surface; performing a pre-curing treatment on the first surface; performing a plate turning treatment on the circuit board; performing a paint film coating treatment on the second surface; and performing a final curing treatment on the first surface and the second surface. By the above-mentioned manner, the paint film coating treatment on the second surface is performed after the plate turning treatment on the circuit board, which can reduce the risk of paint flow caused by gravity when directly performing the paint film coating treatment on the second surface; further, the pre-curing treatment on the first surface before the plate turning can also reduce the risk of paint flow on the paint film coated on the first surface caused by the plate turning, thereby improving the coating effect when coating the double surfaces arranged opposite to each other on the circuit board. BRIEF DESCRIPTION OF DRAWINGS

[0008] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor. Among them: Figure 1 is a flowchart of an embodiment of the coating and curing method of the circuit board of the present application; Figure 2 is a structural schematic diagram of an embodiment of the coating and curing system of the present application; Figure 3 is Figure 2 is a top view schematic diagram of the coating and pre-curing device in the embodiment; Figure 4 is a structural schematic diagram of an embodiment of the coating and curing system of the present application; Figure 5 is an infrared absorption spectrum of the paint film sample tested by the Fourier transform infrared spectrometer. DETAILED DESCRIPTION

[0009] In the following description, specific details are presented in order to provide a thorough understanding of the embodiments of the present application, but the present application can be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary details.

[0010] The terms "first", "second", etc. in this application are used to distinguish different objects, rather than to describe a particular order. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. It should be understood that when used in the specification and the appended claims, the term "include" indicates the presence of described features, integers, steps, operations, elements, and / or components, but does not exclude one or more other features, integers, steps, operations, elements, components, and / or sets thereof. It should also be understood that the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit the application. As used in the specification and the appended claims of this application, the singular forms "a", "an" and "the" are intended to include the plural forms, unless the context clearly indicates otherwise. It should be further understood that the term "and / or" used in the specification and the appended claims of this application means any combination of one or more of the associated listed items and all possible combinations thereof, and includes these combinations.

[0011] As used in the specification and the appended claims of this application, the term "if" can be interpreted as "when" or "upon" or "in response to a determination" or "in response to detecting" depending on the context. Similarly, the phrase "if determined" or "if detected [the described condition or event]" can be interpreted to mean "upon determining" or "in response to determining" or "upon detecting [the described condition or event]" or "in response to detecting [the described condition or event]" depending on the context.

[0012] It should be noted that when an element is fixed to another element, it includes fixing the element directly to the other element, or fixing the element to the other element through at least one other element in the middle. When one element is connected to another element, it includes connecting the element directly to the other element, or connecting the element to the other element through at least one other element in the middle.

[0013] The technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0014] As the core functional carrier of mobile phones, household appliances and other electronic devices, the reliability of the circuit board directly affects the stability and service life of the electronic device. However, the circuit board often faces complex environmental challenges in practical application, such as high temperature and humidity, dust pollution, chemical corrosion (such as acid and alkali gas), mechanical vibration, etc. These factors may cause oxidation of solder joints, metal migration, reduction of insulation performance, and even circuit short circuit, thereby causing device failure.

[0015] In order to improve the protection ability of the circuit board, a functional protective coating can be coated on the surface of the circuit board, for example, a three-proofing paint is coated to form a paint film. After the three-proofing paint is coated, the coating needs to be converted from liquid to solid through a curing process, thereby forming a stable protective structure. Usually, the double sides of the circuit board need to be coated with paint film, but the paint liquid flowing problem may occur, affecting the coating effect.

[0016] The present application first proposes a coating and curing method of a circuit board, as shown in Figure 1 Figure 1 is a flowchart of an embodiment of the coating and curing method of the circuit board of the present application. The circuit board has a first surface and a second surface arranged opposite to each other, and the coating and curing method comprises steps S11 to S15.

[0017] Step S11: coating paint film on the first surface.

[0018] Usually, when coating paint film on the circuit board, in the vertical direction, the first surface faces up as the top surface, and the second surface faces down as the bottom surface.

[0019] In an application scenario, the circuit board of the present embodiment includes a printed circuit board assembly (PCBA), which is a circuit board obtained after installing components on a bare board without any components.

[0020] In order to improve the protection ability of the PCBA, a functional protective coating can be coated on the surface of the PCBA, for example, a three-proofing paint is selected as the coating paint to form a paint film on the surface of the PCBA. The three-proofing paint is a high molecular polymer material, which can form a dense and continuous insulating protective layer on the surface of the PCBA through physical covering and chemical passivation, effectively block the invasion of water vapor, salt mist, dust and corrosive medium, reduce the risk of electric leakage between components, and enhance the ability of the PCBA to resist mechanical vibration.

[0021] In other application scenarios, the circuit board in the present embodiment can also include other types of circuit boards other than printed circuit boards, such as bare boards without components, etc.

[0022] Step S12: pre-curing treatment is performed on the first surface. ​

[0023] In order to improve the stability of the paint film on the first surface during subsequent movement, a pre-curing process is performed; and in order to reduce the risk of paint sagging on the second surface when coating the paint film, the embodiment requires a plate turning process to be performed first to set the second surface upward before coating the paint film on the second surface. Therefore, the pre-curing process is performed on the first surface before the plate turning, which can make the paint film on the first surface dry without flowing, wrinkling and other defects, and inhibit the occurrence of sagging phenomenon of the paint during the plate turning process.

[0024] In some embodiments, step S12 can be implemented in the following manner. Specifically, the first ultraviolet light group is turned on and the paint film region on the first surface is irradiated with the first ultraviolet light group.

[0025] The three-proofing paint used in the paint film coating process includes a photoinitiator. The irradiation of the paint film region with the ultraviolet light group can excite the photoinitiator in the paint film with ultraviolet light, causing rapid curing of the paint film, which can greatly shorten the production cycle, improve the production efficiency of large-scale continuous production, improve the equipment utilization rate, and reduce the cost.

[0026] Although traditional thermal curing (such as oven heating) can achieve coating crosslinking, it has problems such as high energy consumption, long curing time, and damage to temperature-sensitive elements such as lithium batteries. The use of ultraviolet (UV) curing technology and matching UV curing three-proofing paint can significantly shorten the production cycle, reduce equipment energy consumption, and reduce the risk of damage to sensitive elements caused by high temperature.

[0027] The first surface of the circuit board is located at a coating position of the first surface when the paint film coating process is performed, and is located at a pre-curing position when pre-curing. In one application scenario, the coating position and the pre-curing position of the first surface belong to the same position, i.e., without displacement of the circuit board, pre-curing of the circuit board can be achieved. For example, the first ultraviolet light group can be directly arranged near the coating position of the first surface, so that the coating position of the first surface falls within the illumination area of the first ultraviolet light group, and pre-curing of the circuit board is achieved by turning on the first ultraviolet light group. In another application scenario, in response to completion of the paint film coating process on the first surface, the circuit board can be moved to the illumination area of the first ultraviolet light group by controlling the displacement of the first ultraviolet light group. In other application scenarios, the coating position and the pre-curing position of the first surface belong to different positions. For example, in one application scenario, the circuit board can be placed on a conveying track, and the first ultraviolet light group is turned on when the circuit board reaches the illumination area of the first ultraviolet light group.

[0028] During the pre-curing process, the first ultraviolet light group or the circuit board can be further moved based on the curing effect to improve the uniformity of the curing effect of the paint film region on the first surface.

[0029] The control method does not limit the opening and closing of the first ultraviolet light group. For example, the position of the circuit board can be detected by a component such as a photoelectric sensor, and in response to detecting that the circuit board moves to a pre-curing position, the first ultraviolet light is turned on, and in response to the pre-curing time of the circuit board in the pre-curing position reaching a preset time length, the first ultraviolet light is turned off. The relative positions of the circuit board and the first ultraviolet light group can also be determined by other specific identification structures on the circuit board and optical scanning components, and then the timing of turning on and off the first ultraviolet light group is determined. In other application scenarios, the first ultraviolet light group can also be set to remain on all the time, and the pre-curing time is controlled by controlling the residence time of the circuit board in the light irradiation area of the first ultraviolet light group.

[0030] In some embodiments, the power of the first ultraviolet light group is adjustable. For example, the power when it is working can be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% of the rated power or maximum power, etc. Such a setting can adjust the power of the first ultraviolet light group based on the characteristics of the circuit board or the paint film, the target pre-curing effect, and improve the multi-scene applicability of the first ultraviolet light group. In some embodiments, the power of the first ultraviolet light group can be set to stepless adjustment.

[0031] In some embodiments, the peak value of the power density of the first ultraviolet light group is 1300 mW / cm 2 .

[0032] In some embodiments, the first ultraviolet light includes a Light Emitting Diode (LED) lamp.

[0033] The LED lamp has high electro-optical conversion efficiency, and the conversion rate can reach 45%-50%. Using an LED lamp as an ultraviolet light can improve energy efficiency, reduce energy consumption, and be safer. Further, the LED lamp can be used immediately without waiting for preheating or cooling, and is suitable for short-period, multi-batch curing needs.

[0034] In some embodiments, the first ultraviolet light group includes at least one LED lamp.

[0035] In some embodiments, the light source emitted by the LED lamp is a surface light source, and the wavelength band of the ultraviolet light emitted is 360 nm-370 nm, such as 360 nm, 362 nm, 365 nm, 368 nm, or 370 nm, etc. In other embodiments, other wavelength bands can also be selected, such as 385 nm, 395 nm, or 405 nm, etc. In some embodiments, an LED lamp with a matching degree greater than or equal to 90% with the absorption wavelength of the coating paint used can be selected, which can improve the curing effect and curing speed during the pre-curing process.

[0036] In some embodiments, the first ultraviolet light group composed of the LED lamps has a rated power of 950 W.

[0037] In some embodiments, the pre-curing treatment has a processing time of less than or equal to 5 s.

[0038] This arrangement can not only make the paint film on the first surface after pre-curing dry and not flow, but also reduce the pre-curing time, improve the pre-curing efficiency, and reduce the risk of paint film yellowing and aging.

[0039] In some embodiments, the ultraviolet light emitted by the light-emitting diode lamp has a wavelength range of 360 nm to 370 nm, the power density of the light-emitting diode lamp is 480 mW / cm 2 - 940 mW / cm 2 , and the pre-curing treatment has a processing time of greater than 0.35 s and less than or equal to 0.8 s.

[0040] The greater the power density, the stronger the light intensity, and the faster the curing speed. In order to reduce the risk of paint film yellowing and aging, it is necessary to set appropriate pre-curing treatment processing time and light intensity. In order to achieve better pre-curing effect and reduce the risk of paint sagging when the board is flipped, the pre-curing treatment processing time cannot be too short and the light intensity cannot be too low. In an application scenario, the circuit board is conveyed by a chain, and the time for the circuit board to be irradiated by the LED lamp can be controlled by controlling the chain conveying speed, so that the pre-curing treatment processing time of the circuit board can be controlled. The greater the chain speed, the shorter the irradiation time, i.e. the shorter the pre-curing treatment processing time. When the irradiation time is short, the light intensity can be increased to improve the curing efficiency; wherein the power of the LED lamp is adjustable, and the light intensity can be increased by increasing the power density of the LED lamp. Preferably, the working power of the LED lamp during operation can be set to 50%, 60%, 70%, 80%, 90%, or 100% of the maximum power or rated power, etc., which is convenient for operation. For example, the power density of the LED lamp can be set to 480 mW / cm 2 , 481 mW / cm 2 , 500 mW / cm 2 , 510 mW / cm 2 , 530 mW / cm 2 , 560 mW / cm 2 , 600 mW / cm 2 , 630 mW / cm 2 , 650 mW / cm 2 , 660 mW / cm 2 , 670 mW / cm 2 , 690 mW / cm 2 , 710 mW / cm 2 , 720 mW / cm 2 , 730 mW / cm2 , 732 mW / cm 2 , 735 mW / cm 2 , 786 mW / cm 2 , 790 mW / cm 2 , 800 mW / cm 2 , 834 mW / cm 2 , 840 mW / cm 2 , 845 mW / cm 2 , 885 mW / cm 2 , 890 mW / cm 2 , 900 mW / cm 2 , 923 mW / cm 2 , 930 mW / cm 2 , 937 mW / cm 2 , or 940 mW / cm 2 , etc.

[0041] In some embodiments, the pre-curing treatment time is greater than 0.35 s and less than or equal to 0.8 s, such as 0.35 s, 0.38 s, 0.40 s, 0.41 s, 0.42 s, 0.45 s, 0.46 s, 0.47 s, 0.48 s, 0.50 s, 0.51 s, 0.55 s, 0.56 s, or 0.60 s, etc. Such a setting not only reduces the risk of yellowing and aging of the paint film, but also achieves better pre-curing effect, reducing the risk of paint film sagging when turning over. Further, such a setting is easy to operate, which can reduce the difficulty of operation, reduce the failure rate caused by operation errors, and reduce the difficulty and cost of production.

[0042] In some embodiments, referring to Table 1, Table 1 gives a combination scheme of multiple groups of illumination time and LED lamp power density. Among them, the A scheme is the recommended preferred scheme, under which better pre-curing effect can be obtained, and the paint film will not yellow and age, for example, when the power density is 481 mW / cm 2 and the illumination time is 0.6 s, 0.47 s or 0.38 s, better pre-curing effect can be obtained, and it is simple and low-cost to operate, which is convenient for industrial production. Although the B scheme can also obtain certain pre-curing effect, it is usually difficult to operate, high in cost, and prone to operation errors that cause damage to the paint film, such as incomplete pre-curing or yellowing and aging of the paint film, which increases the failure rate, for example, when the power density is 105 mW / cm 2 and the illumination time is 1.9 s, better pre-curing effect can be obtained, but it is not easy to operate. When the C scheme is used, the illumination time is too long or the light intensity is too high, which will cause the paint film to be over-irradiated and yellow and age, for example, when the power density is 560 mW / cm 2and the light exposure time is 1.9s. When the D scheme is used, the light exposure time is too short or the light intensity is too weak, only the surface of the paint film is cured, the curing depth is too shallow, and paint film sagging phenomenon is prone to occur when the plate is turned over. For example, when the power density is 105mW / cm 2 and the light exposure time is 0.9s. When the E scheme is used, the light exposure time is the shortest and the light intensity is the strongest, similar to the B scheme, the operation is difficult and prone to errors, and the curing depth of the paint film is too shallow, which is difficult to achieve good pre-curing effect.

[0043] Table 1 Comparison table of light exposure time and LED lamp power density combination scheme experimental effect

[0044] In some embodiments, when the chain conveying circuit board is used, the control of the chain conveying speed can control the moving speed of the circuit board, and then the light exposure time can be controlled. In an application scenario, the chain speed is controlled to be 200r / min, the moving speed of the circuit board can be 2.6cm / s, and the light exposure time is 1.9s. The corresponding relationship of the chain speed, the moving speed of the circuit board and the light exposure time can be referred to Table 2.

[0045] Table 2 Comparison table of light exposure time and chain speed, moving speed of circuit board

[0046] For example, the chain speed is controlled to be 600r / min, the moving speed of the circuit board can be 8.5cm / s, and the light exposure time is 0.6s. In some application scenarios, due to the influence of the size of the circuit board, the light exposure time of each circuit board will be slightly different, and the light exposure time of the circuit board can be optimized by controlling the chain speed, so that the light exposure time is within the range defined in the A scheme of Table 1.

[0047] In other application scenarios, the light exposure time of the circuit board can also be controlled by other ways, for example, a dynamic light shielding plate is arranged on the lamp, and the specific limitation is not limited.

[0048] In other embodiments, based on the actual production requirements for the processing time of the pre-curing treatment, the processing time can also be set to 0.8s, 0.9s or 0.3s, etc., and the power density of the LED lamp can be adjusted accordingly.

[0049] The light source size of the first ultraviolet light group can be set based on the size of the circuit board. In an application scenario, the light source size is set to 304 mm in length and 116 mm in width. The length can also be 300 mm, 301 mm, 303 mm, 305 mm, or 310 mm, and the width can also be 110 mm, 114 mm, 115 mm, 118 mm, or 120 mm. Such a setting can adapt to most sizes of circuit boards and improve the multi-scene applicability of the first ultraviolet light group.

[0050] Step S13: Turn the circuit board over.

[0051] The circuit board is turned over before the second surface is coated with a paint film. This can reduce the risk of paint dripping due to gravity when the second surface is directly coated with a paint film. In an application scenario, the circuit board can be turned over using a board turning assembly. In an application scenario, the coating and curing method is used in a coating and curing system. After the circuit board is pre-cured, the circuit board can be conveyed again to a coating position by a conveying assembly of the coating and curing system. The board can be turned over during the conveying process or after the circuit board reaches the coating position.

[0052] In some embodiments, step S13 can be implemented by turning the circuit board over in response to the transmittance of the Fourier infrared absorption spectrum of the paint film region on the first surface at the M wave number being greater than or equal to a first predetermined value and the transmittance at the N wave number being less than or equal to a second predetermined value. The M wave number corresponds to the absorption peak of the C-H bond stretching vibration characteristic of the alkyl chain of the paint film, and the N wave number corresponds to the absorption peak of the C=C double bond stretching vibration characteristic of the paint film.

[0053] It should be noted that in the spectrum of the Fourier infrared absorption spectrum, the wave number represents the energy of the infrared light, and the wave number is the inverse of the wavelength. The transmittance represents the ratio of the energy of the infrared light after passing through the sample to the energy of the incident light. In the Figure 5 In the embodiments shown, the blue curve represents the infrared absorption spectrum of the paint film under the traditional curing process, the red curve represents the infrared absorption spectrum of the paint film stock solution, and the magenta curve represents the infrared absorption spectrum of the paint film using the pre-curing and final curing process of the present embodiment.

[0054] In an application scenario, the paint film is prepared from the following components by weight percentage: polyurethane acrylate 30%-70%, acrylate monomer 10%-30%, and photoinitiator 0.2%-1%. The M wave number of the paint film is 2900 cm -1 , and the N wave number is 1630 cm -1 . For example, the first predetermined value can be 87%, and the second predetermined value can be 81%. In response to the Fourier infrared absorption spectrum of the paint film region on the first surface at 2900 cm-1 transmittance at wave number 2900 cm-1 is greater than or equal to 87%, and the transmittance at wave number 1630 cm-1 is less than or equal to 81%. -1 transmittance at wave number 2900 cm-1 is less than 87%, and the transmittance at wave number 1630 cm-1 is less than or equal to 81%.

[0055] transmittance at wave number 2900 cm-1 is greater than or equal to 87%, and the transmittance at wave number 1630 cm-1 is less than or equal to 81%. -1 corresponding to the absorption peak of C-H bond stretching vibration characteristics on the alkyl chain of the paint film, when the Fourier infrared absorption spectrum of the paint film region on the first surface is 2900 cm-1 -1 transmittance at wave number 2900 cm-1 is greater than or equal to 87%, indicating that the chemical environment of the C-H bond is stable and has not been significantly broken or oxidized, meaning that the molecular structure of the paint film is complete, so the Fourier infrared absorption spectrum of the paint film region on the first surface is 2900 cm-1 -1 transmittance at wave number 2900 cm-1 is controlled to be greater than or equal to 87%, which can effectively reduce the risk of paint film thermal degradation and aging at the microscopic level in advance. Transmittance at wave number 2900 cm-1 is greater than or equal to 87%, and the transmittance at wave number 1630 cm-1 is less than or equal to 81%. -1 transmittance at wave number 2900 cm-1 is less than 87%, which is an early warning indicator of paint film thermal degradation and aging, and needs to be intervened in priority to prevent yellowing. In some embodiments, the wave number 2950 cm-1 -1 corresponding to the absorption peak of C-H bond stretching vibration characteristics on the alkyl chain of the paint film, for example, the first preset value can be taken as 80%.

[0056] transmittance at wave number 1630 cm-1 is less than or equal to 81%. -1 corresponding to the absorption peak of C=C double bond stretching vibration characteristics in (meth)acrylate and other photosensitive resins, when the Fourier infrared absorption spectrum of the paint film region on the first surface is 1630 cm-1 -1 transmittance at wave number 1630 cm-1 is less than or equal to 81%, indicating that the double bond in the resin is largely consumed and participates in the photopolymerization crosslinking reaction and is converted into a single bond, so the Fourier infrared absorption spectrum of the paint film region on the first surface is 1630 cm-1 -1 transmittance at wave number 1630 cm-1 is controlled to be less than or equal to 80%, which can monitor the progress of the polymerization crosslinking reaction and ensure that the pre-curing is sufficient, which can effectively reduce the risk of paint film wrinkling or surface drying failure caused by incomplete pre-curing. Transmittance at wave number 1630 cm-1 is less than or equal to 80%. -1 transmittance at wave number 1630 cm-1 is greater than 81%, which has the risk of incomplete curing and is prone to cause paint film wrinkling or surface drying failure.

[0057] Further, the transmittance at L wave number corresponding to the absorption peak of isocyanate group (-NCO) stretching vibration characteristic in the paint film can also be detected simultaneously. The peak value of the absorption peak gradually weakens to some extent as the curing process proceeds. The transmittance at L wave number can be taken as one of the first predetermined intervals for the turning plate condition, and the first predetermined interval can be determined based on the raw materials for preparing the paint film. For example, the raw materials for preparing the paint film include the following components by weight percentage: polyurethane acrylate 30%-70%, acrylate monomer 10%-30%, and photoinitiator 0.2%-1%. The M wave number corresponding to the paint film is 2900 cm -1 , the N wave number is 1630 cm -1 , and the L wave number is 2260 cm -1 . For example, the first predetermined interval can be set to be greater than or equal to 85% and less than 86%, or equal to 85%, or equal to 89%, etc.

[0058] Referring to Table 3, Table 3 shows the transmittance corresponding to the wave number of different typical absorption peaks in different appearances after pre-curing. The raw liquid appearance refers to the transmittance corresponding to the wave number of different typical absorption peaks of the raw liquid without pre-curing, the film soft appearance refers to the transmittance corresponding to the wave number of different typical absorption peaks when the paint film is formed after curing treatment and the paint film is soft, the certain strength appearance refers to the transmittance corresponding to the wave number of different typical absorption peaks when the paint film has a certain strength after curing treatment, the original process appearance refers to the transmittance corresponding to the wave number of different typical absorption peaks of the finished paint film in the traditional process, and the yellowing appearance refers to the transmittance corresponding to the wave number of different typical absorption peaks when the paint film is formed after curing treatment and the paint film is yellowed.

[0059] Table 3 Transmittance corresponding to the wave number of different typical absorption peaks in different appearances

[0060] For example, when the transmittance of the Fourier infrared absorption spectrum of the paint film region on the first surface at the wave number 2950 cm -1 is 81.6%, the transmittance at the wave number 2900 cm -1 is 89.4%, the transmittance at the wave number 2260 cm -1 is 89%, and the transmittance at the wave number 1630 cm -1 is 79.3%, at this time, the paint film is pre-cured to a certain strength state and is not aged, and the circuit board can be turned over for processing; for another example, when the transmittance of the Fourier infrared absorption spectrum of the paint film region on the first surface at the wave number 2950 cm -1 is 80%, the transmittance at the wave number 2900 cm -1 is 87.1%, the transmittance at the wave number 2260 cm -185%, wave number 1630 cm -1 When the transmittance at wave number 2950 cm -1 When the transmittance at wave number 2900 cm -1 When the transmittance at wave number 2260 cm -1 When the transmittance at wave number 1630 cm -1 When the transmittance at wave number 1630 cm

[0061] In other application scenarios, the specific values of at least one of the first predetermined value, the second predetermined value, the M wave number, the N wave number, and the L wave number can be adjusted based on the raw material of the paint film. In the production process, the length of time for pre-curing and the timing of plate turning are controlled by referring to the Fourier infrared absorption spectrum, which can significantly reduce the defect rate of finished products, effectively monitor the pre-curing effect, improve the control accuracy of the pre-curing effect, and improve the pre-curing effect.

[0062] Step S14: coating a paint film on the second surface.

[0063] The coating position of the circuit board when the second surface is coated with a paint film can be different from or the same as the coating position of the circuit board when the first surface is coated with a paint film, and is not limited. In an application scenario, the circuit board is arranged on the conveying assembly of the coating and curing system and is conveyed in one direction. The coating position of the circuit board when the second surface is coated with a paint film is different from the coating position of the circuit board when the first surface is coated with a paint film and is arranged along the conveying direction. The pre-curing position is arranged between the two coating positions. This arrangement is suitable for production scenarios with a large output and can effectively improve production efficiency. In another application scenario, only one coating position is provided for coating the second surface or the first surface with a paint film. When the orientation of the pre-curing position and the coating position is different, the circuit board can be conveyed back to the coating position after the pre-curing treatment of the circuit board is completed. This arrangement is suitable for production scenarios with a small output and can effectively save the length of the production line.

[0064] Step S15: performing final curing treatment on the first surface and the second surface.

[0065] Step S15 realizes complete curing of the paint film on the surface of the circuit board through final curing.

[0066] By the above manner, the second surface is coated with paint film after the circuit board is flipped in steps S11-S15, which can reduce the risk of paint dripping due to gravity when the second surface is directly coated with paint film. Further, the first surface is pre-cured before flipping, which can also reduce the risk of paint dripping on the first surface due to flipping, thereby improving the coating effect when the double sides of the circuit board are coated with paint film.

[0067] In some embodiments, step S15 can be implemented by irradiating the paint film area on the first surface and the second surface with the second ultraviolet light lamp set to complete the final curing treatment.

[0068] After the second surface is coated with paint film, the first surface and the second surface are directly subjected to final curing treatment without flipping. For example, in an application scenario, after the second surface is coated with paint film, the circuit board is moved to the final curing position without flipping, and the first surface and the second surface are subjected to final curing treatment at this time, and the second surface is on top, which can reduce the risk of paint dripping. In some application scenarios, in order to reduce the interference of the change of the moving speed on the paint film coating and curing effect on the circuit board and improve the production efficiency of the production line, the circuit board can be moved through the coating position of the second surface at a preset speed to complete the coating of the second surface, and then moved to the final curing position at a preset speed to complete the final curing of the double sides of the circuit board, i.e., the first surface and the second surface are subjected to final curing treatment at the same time. In this process, a double-sided curing device such as a mercury lamp double-sided curing furnace can be used. For example, in other application scenarios, after the second surface is coated with paint film, the second surface can be subjected to final curing, and then flipped again to coat the first surface with paint film. The specific implementation is not limited.

[0069] The positional relationship between the coating position of the first surface and the coating position of the second surface is not limited, for example, the coating position of the first surface and the coating position of the second surface can be arranged in the same direction, which can reduce the length of the production line and save space.

[0070] In some embodiments, the second ultraviolet light lamp set includes at least two groups of high-pressure mercury lamps, one group of high-pressure mercury lamps is used to irradiate the paint film area on the first surface, and the other group of high-pressure mercury lamps is used to irradiate the paint film area on the second surface, and the light energy density of the other group of high-pressure mercury lamps is greater than that of one group of high-pressure mercury lamps.

[0071] The above arrangement can realize simultaneous final curing of the first surface and the second surface by two groups of high-pressure mercury lamp groups, thereby improving the curing efficiency. In an application scenario, the two groups of high-pressure mercury lamp groups are arranged on the upper and lower sides of the circuit board respectively. One group of high-pressure mercury lamp groups is arranged close to the first surface to irradiate the paint film area on the first surface, and the other group of high-pressure mercury lamp groups is arranged close to the second surface to irradiate the paint film area on the second surface, thereby reducing the length of the production line. In an application scenario, this arrangement can realize the final curing process by using one mercury lamp double-sided curing device, without the need to arrange two groups of mercury lamp curing devices, thereby reducing the cost.

[0072] Since the first surface has undergone a pre-curing process, it requires less time for final curing. In this embodiment, the light energy density of the group of high-pressure mercury lamps arranged to irradiate the paint film area on the second surface is greater than that of the group of high-pressure mercury lamps arranged to irradiate the paint film area on the first surface, thereby improving the curing speed of the second surface, shortening the time required for curing the second surface, improving the synchronization of the final curing effect of the first surface and the second surface, and improving the final curing efficiency.

[0073] In some application scenarios, one group of high-pressure mercury lamp groups includes at least one lamp tube and a power supply for controlling the operation of the lamp tube.

[0074] The group of high-pressure mercury lamps can emit high-intensity broadband ultraviolet light by exciting mercury vapor through high-voltage discharge. For example, the wavelength range of the broadband ultraviolet light emitted by the group of high-pressure mercury lamps can reach 200 nm-450 nm, which can cover multiple key wavebands (such as 254 nm, 303 nm, 313 nm, 365 nm, 405 nm, 436 nm, etc.), and the light intensity of the ultraviolet light emitted by the group of high-pressure mercury lamps is particularly significant in the short-wave ultraviolet light region and the long-wave ultraviolet light region.

[0075] If the first ultraviolet light group includes LED lamps and is used to emit single or a small number of narrow-band ultraviolet light, such as 385 nm or 395 nm, etc., the group of high-pressure mercury lamps can supplement short-wave ultraviolet energy, such as 254 nm, 303 nm, etc. These short-wave energies can more efficiently break chemical bonds in photoinitiator molecules, generate more free radicals, accelerate crosslinking reactions, and improve curing efficiency. For some photoinitiators that require multi-waveband synergistic effect, the broadband output of the group of high-pressure mercury lamps can provide more comprehensive excitation conditions, thereby improving the overall curing efficiency. Further, the short-wave ultraviolet light emitted by the group of high-pressure mercury lamps has the characteristics of high energy and strong penetration, which can penetrate deeply into the interior of the thick paint film and directly excite the photoinitiator in the deep layer, thereby realizing synergistic complementation with the narrow-spectrum shallow curing of the LED lamps and reducing the probability of the occurrence of the problem of "surface dryness and internal dryness".

[0076] In some application scenarios, the coating and curing method of the present embodiment can be used for PCBA with high components whose height is greater than 3mm, high-density PCBA with component spacing less than or equal to 2mm, etc. Such PCBA will have component shadow effect during light curing, and the illumination of the area blocked by the component shadow will decay by 70%-90% during light curing. When only using conventional single-wavelength LED lamps for curing, due to the limited light penetration depth and component shadow effect, there will be a problem of local poor curing. When only using conventional mercury lamps for curing, there will be problems of high energy consumption, low efficiency, and safety hazards. Using the curing method of the present embodiment to coat and cure such PCBA, setting the curing mechanism of combining LED lamp pre-curing and high-pressure mercury lamp group final curing, can reduce energy consumption, improve overall curing efficiency and curing effect, and reduce safety hazards.

[0077] In some embodiments, the rated power of one group of high-pressure mercury lamp groups is 3kW, and the total rated power of two groups of high-pressure mercury lamp groups is 6kW. In other embodiments, the power of the high-pressure mercury lamp groups can also be adjusted based on the size and moving speed of the circuit board and the composition of the paint film.

[0078] In some embodiments, the power of the high-pressure mercury lamp groups can be steplessly adjusted.

[0079] In some embodiments, the circuit board is conveyed by the conveying assembly of the coating and curing system along the conveying track, and two groups of high-pressure mercury lamp groups are distributed on the upper and lower sides of the track, i.e. arranged perpendicular to the direction of the track, so as to directly cure the circuit board located on the conveying track.

[0080] In one application scenario, the ultraviolet light waveband emitted by one group of high-pressure mercury lamp groups is 320nm-420nm, and the main peak is 365nm.

[0081] In other embodiments, the second surface can also be pre-cured. For example, the second surface can be pre-cured by using an ultraviolet light lamp such as an LED lamp during conveying the circuit board to the final curing position.

[0082] In some embodiments, the coating paint used in the coating film processing is a three-proofing paint, which at least includes polyurethane acrylate, acrylate monomer, photoinitiator 2,4,6-trimethylbenzoyl diphenyl phosphine oxide (TPO), antioxidant, fluorescent agent, and leveling agent; wherein the content of the polyurethane acrylate value can be 30%-70%, for example, 30%, 40%, 50%, 60%, or 70%, etc.; wherein the content of the acrylate monomer can be 10%-30%, for example, 10%, 20%, or 30%, etc.; wherein the content of the photoinitiator TPO can be 0.2%-1%, for example, 0.2%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, or 1%, etc.

[0083] In other embodiments, similar improvements can be made to the first ultraviolet light lamp group and the second ultraviolet light lamp group, which will not be described here.

[0084] The present application further proposes a coating and curing system, as shown in Figures 2 to 4 The coating and curing system 11 is used for a circuit board having a first surface and a second surface arranged opposite to each other, and includes a coating and pre-curing device 12 and a final curing device 13. The coating and pre-curing device 12 is used for sequentially performing coating film processing on the first surface, pre-curing processing on the first surface, flipping processing on the circuit board, and coating film processing on the second surface. The final curing device 13 is used for performing final curing processing on the first surface and the second surface.

[0085] The coating and curing system 11 of the present embodiment can perform pre-curing processing on the first surface before performing coating film processing on the second surface of the circuit board, thereby reducing the risk of paint flow caused by the paint film coated on the first surface due to flipping, and further improving the convenience and coating effect when coating film processing is performed on the two opposite surfaces of the circuit board.

[0086] In some embodiments, referring to Figure 2 , Figure 3 The coating and pre-curing device 12 includes a coating assembly (not labeled in the figure), a pre-curing assembly 121, and a flipping assembly (not labeled in the figure). The coating assembly is used for performing coating film processing on the first surface and the second surface. The pre-curing assembly 121 is used for performing pre-curing processing on the first surface. The flipping assembly is used for performing flipping processing on the circuit board.

[0087] In an application scenario, the coating assembly includes a glue spraying assembly, which can be used for spraying coating paint on the first surface and the second surface.

[0088] In some embodiments, referring to Figure 3During the circuit board flipping process, the flipping position 20 is located at the coating position 10 on the first surface; in other embodiments, the flipping position 20 may also be located close to the coating position 10 on the first surface. This arrangement can reduce the overall size of the coating pre-curing device 12.

[0089] In some embodiments, see Figure 3 The pre-curing component 121 includes a first ultraviolet lamp group 1211. The working principle and specific implementation method of the first ultraviolet lamp group 1211 can be found in the above embodiments, and will not be repeated here.

[0090] The coating position 10 on the first surface is located during the coating process and the pre-curing position during pre-curing. In one application scenario, the coating position 10 and the pre-curing position on the first surface are in the same orientation, meaning that pre-curing of the circuit board can be achieved without displacement of the circuit board, as described in the above embodiment. In other application scenarios, the coating position 10 and the pre-curing position on the first surface are in different orientations. For example, the coating curing system 11 or the coating pre-curing device 12 further includes a first conveying component 123, which includes a conveying track. The circuit board is placed on the conveying track. When the circuit board follows the conveying track to the coating position 10 on the first surface, the first surface is coated. When the circuit board follows the conveying track to the illumination area of ​​the first ultraviolet lamp group 1211, the first ultraviolet lamp group 1211 is turned on.

[0091] In some embodiments, the first conveying component 123 includes a conveying track and a moving component, the conveying track and the moving component being capable of adjusting the position of the circuit board to change in multiple orientations. Similar improvements may be made to the first conveying component 123 in other embodiments.

[0092] In some embodiments, see Figure 3 The coating pre-curing device 12 includes a coating position 10 for coating the first surface and the second surface with a paint film. That is, the coating position 10 is the coating position of the first surface and the coating position of the second surface.

[0093] In one application scenario, refer to Figure 2 , Figure 3The circuit board is conveyed into the coating and pre-curing device 12 by the first conveying assembly 123, the code scanning assembly of the coating and pre-curing device 12 scans and identifies the identification code on the circuit board, and the control assembly of the coating and pre-curing device 12 calls the corresponding control program based on the scanning result. The coating and pre-curing device 12 further comprises a positioning part for positioning the circuit board, which can comprise a visual positioning member or an ultrasonic positioning member, etc. The circuit board has a specific position point or a preset electronic element which can be identified by the positioning part, and the coating and pre-curing device 12 can position the specific position point or the preset electronic element by the positioning part, and adjust the position of the circuit board on the first conveying assembly 123 according to the positioning condition, so as to accurately adjust the circuit board to the specified glue spraying position, i.e. the coating position 10. For example, the first conveying assembly 123 comprises a conveying track and a moving assembly, which can adjust the position of the circuit board to change in multiple directions. After the coating film treatment on the first surface is completed, the first conveying assembly 123 conveys the circuit board to the pre-curing position, and the first ultraviolet lamp set 1211 of the pre-curing assembly 121 is turned on to perform the pre-curing treatment on the first surface. After the pre-curing treatment on the first surface is completed, the first ultraviolet lamp set 1211 is turned off, the circuit board is returned to the coating position 10 along with the first conveying assembly 123, the flipping treatment and the positioning treatment are performed, so that the second surface is located in the coating area of the coating assembly, and then the coating film treatment is performed on the second surface. After the coating film treatment on the second surface is completed, the circuit board is conveyed out of the coating and pre-curing device 12 along with the first conveying assembly 123, for example, directly conveyed to the final curing device 13.

[0094] The control assembly is connected with the code scanning assembly, the first conveying assembly 123, the coating assembly, the flipping assembly and the pre-curing assembly 121, and is used for controlling the working of the above-mentioned assemblies.

[0095] In some embodiments, the coating and curing system 11 further comprises a first inspection member 14. After the coating film treatment on the second surface is completed, the first conveying assembly 123 conveys the circuit board to the first inspection member 14, the first inspection member 14 performs the inspection treatment on the coating effect of the second surface, and after the inspection is completed, the circuit board is conveyed out of the coating and pre-curing device 12. In some embodiments, the first inspection member 14 can also perform the inspection on the coating and pre-curing effect of the first surface.

[0096] In some embodiments, the coating and curing system 11 further comprises a third inspection member 16. After the final curing treatment on the first surface and the second surface is completed, the circuit board is conveyed to the third inspection member 16, and the third inspection member 16 performs the inspection treatment on the curing effect of the circuit board.

[0097] In some embodiments, referring to Figure 4The coating and pre-curing device 12 comprises a first coating machine 124, a pre-curing assembly 121, a board flipping assembly 122, a second coating machine 125, and a first conveying assembly 123. The first coating machine 124 is configured to perform coating film processing on the first surface. The pre-curing assembly 121 is configured to perform pre-curing processing on the first surface. The board flipping assembly 122 is configured to perform board flipping processing on the circuit board. The second coating machine 125 is configured to perform coating film processing on the second surface. The first conveying assembly 123 is configured to convey the circuit board.

[0098] In this way, the first coating machine 124 and the second coating machine 125 can be used to perform coating processing on the first surface and the second surface respectively. That is, the coating position on the first surface and the coating position on the second surface are arranged separately. This can improve the production efficiency of the production line and is suitable for production scenarios with large production capacity.

[0099] In some embodiments, the first conveying assembly 123 comprises a conveying track and a moving assembly, which can adjust the position of the circuit board to change in multiple directions. Similar improvements can also be made to the first conveying assembly 123 in other embodiments.

[0100] In an application scenario, referring to Figure 4 The circuit board is conveyed into the first coating machine 124 by the first conveying assembly 123. The code scanning assembly of the coating and pre-curing device 12 scans and identifies the identification code on the circuit board. The control assembly of the coating and pre-curing device 12 retrieves the corresponding control program based on the scanning result. The coating and pre-curing device 12 further comprises a positioning part for positioning the circuit board. The positioning part can comprise a visual positioning member or an ultrasonic positioning member, etc. The circuit board has a specific position point or a preset electronic component that can be identified by the positioning part. The coating and pre-curing device 12 can position the specific position point or the preset electronic component by the positioning part and adjust the position of the circuit board on the first conveying assembly 123 according to the positioning condition, so as to accurately adjust the circuit board to a specified glue spraying position. After the coating film processing on the first surface is completed, the first conveying assembly 123 conveys the circuit board to the pre-curing position. The first ultraviolet light group 1211 of the pre-curing assembly 121 is turned on to perform pre-curing processing on the first surface. After the pre-curing processing on the first surface is completed, the first ultraviolet light group 1211 is turned off. The board flipping assembly 122 performs board flipping processing on the circuit board. The circuit board is conveyed to the second coating machine 125 by the first conveying assembly 123, positioned, and then subjected to coating film processing on the second surface. After the coating film processing on the second surface is completed, the circuit board is conveyed out of the coating and pre-curing device 12 by the first conveying assembly 123, for example, directly to the final curing device 13.

[0101] In some embodiments, referring to Figure 4The coating and curing system 11 further comprises a first inspection device 14. After the second surface is coated with the paint film, the first conveying assembly 123 conveys the circuit board to the first inspection device 14, which inspects the coating effect of the second surface. After the inspection, the circuit board is conveyed out of the coating and pre-curing device 12.

[0102] In some embodiments, referring to Figure 4 , the pre-curing assembly comprises a first ultraviolet light lamp set 1211 and a second inspection device (not shown). After the first surface is coated with the paint film, the first conveying assembly 123 conveys the circuit board to the pre-curing assembly. The first inspection device 14 inspects the coating effect of the first surface. After the inspection, the first ultraviolet light lamp set 1211 pre-cures the circuit board. In some embodiments, the second inspection device can also inspect the pre-curing effect of the first surface.

[0103] In some embodiments, referring to Figure 2 , Figure 4 , the coating and curing system 11 further comprises a feeding assembly 15, which conveys the circuit board to the first conveying assembly 123.

[0104] In some embodiments, referring to Figure 2 , Figure 4 , the coating and curing system 11 further comprises a third inspection device 16. After the first surface and the second surface are finally cured, the circuit board is conveyed to the third inspection device 16, which inspects the curing effect of the circuit board.

[0105] In some embodiments, referring to Figure 4 , the first coating machine 124, the pre-curing assembly 121, the board flipping assembly 122, the second coating machine 125, the first inspection device 14, the final curing device 13, and the third inspection device 16 are arranged in sequence along the conveying direction of the first conveying assembly 123.

[0106] When the first inspection device 14 fails to pass the inspection, the first conveying assembly 123 can be controlled to convey the circuit board back to the corresponding second coating machine 125 for secondary coating of the second surface to improve the coating effect. In an application scenario, if the circuit board still fails to pass the inspection after multiple times of back conveying, the circuit board can be controlled to exit the conveying track and be treated as a defective product. When the second inspection device or the third inspection device 16 fails to pass the inspection, similar treatment can be performed according to the implementation of the first inspection device 14 failing to pass the inspection.

[0107] In some embodiments, the final curing device 13 comprises a mercury lamp double-sided curing device.

[0108] In some embodiments, the mercury lamp double-sided curing device comprises a second conveying assembly (not shown), which is used to drive the circuit board to enter and exit the mercury lamp double-sided curing device.

[0109] In some embodiments, the mercury lamp double-sided curing device comprises a second ultraviolet light lamp group. The specific implementation and working principle of the second ultraviolet light lamp group can refer to the above embodiments, which will not be repeated here.

[0110] In some embodiments, the second conveying assembly at least comprises a conveying track on which the circuit board is arranged; the second ultraviolet light lamp group comprises at least two groups of high-pressure mercury lamp groups, one group of high-pressure mercury lamp groups is used to irradiate the paint film area on the first surface, and the other group of high-pressure mercury lamp groups is used to irradiate the paint film area on the second surface, and the light energy density of the other group of high-pressure mercury lamp groups is greater than that of one group of high-pressure mercury lamp groups. The specific implementation and working principle of the two groups of high-pressure mercury lamp groups can refer to the above embodiments.

[0111] In some embodiments, compared with the curing mechanism of using two separate mercury lamp single-sided curing devices to perform one-time curing on the first surface and the second surface respectively in the traditional curing mechanism, the curing mechanism of combining LED lamp pre-curing and high-pressure mercury lamp group final curing in the present embodiment can reduce energy consumption by about 50%, and at least increase unit production capacity by about 30%. Since the mercury lamp single-sided curing device is relatively large, the combination of the coating pre-curing integrated coating pre-curing device 12 and the mercury lamp double-sided curing device can save about 15%-25% of the production line space, and such a setting can also achieve good curing effect. For example, when testing the infrared absorption spectrum of the cured paint film by using a Fourier Transform Infrared Spectroscopy (FTIR), the characteristic spectrum peak consistent with the traditional curing mechanism can be obtained.

[0112] In the prior art, the first surface and the second surface usually need to be coated with paint film in sequence. In order to prevent paint film sagging when the plate is turned over, the coating, final curing and inspection of the first surface need to be completed before the plate is turned over, and then the coating, final curing and inspection of the second surface are performed. In the case of large production demand, in order to ensure production efficiency, two sets of coating devices, mercury lamp single-sided curing furnaces and corresponding inspection devices need to be used, the production line structure is too long, and the cost of the mercury lamp curing furnace is high. Even in the case of small production demand, in order to shorten the production line, only one set of coating device, mercury lamp single-sided curing furnace and corresponding inspection device is used, and the coating and curing of the first surface need to be changed to the coating and curing of the second surface after completion, which will greatly increase the production cycle of a single circuit board. In the case of large demand for circuit boards, the use of the present embodiment Figure 4The coating and curing system 11 shown can save a final curing unit, shorten the production line length, reduce costs, and increase the unit capacity of the production line. This embodiment is suitable for production scenarios involving multiple different types or models of circuit boards with small batch requirements. Figure 2 , Figure 3 The coating and curing system 11 shown can coat, pre-cur, and flip circuit boards through a coating pre-curing device 12, which can effectively save line replacement time and significantly reduce the production cycle of coating and curing a single circuit board.

[0113] For example, in one application scenario, the circuit board includes a composite epoxy material-3 (CEM-3) copper clad laminate, using... Figure 4 The coating pre-curing device 12 shown coats and cures the surface. The coating thickness is greater than or equal to 40 μm. The first ultraviolet lamp group 1211 is an LED lamp, and the power density of the LED lamp, used as a surface light source, is 480 mW / cm² during operation. 2 The conveyor chain of the conveyor assembly rotates at 1000 r / min, resulting in a pre-curing time of 0.38 s. During the final curing process, the conveyor speed of the second conveyor assembly and the power density of the high-pressure mercury lamp assembly are adjusted to set the light energy density of the high-pressure mercury lamp assembly used for photo-irradiation of the first surface to 1000 mJ / cm². 2 The light energy density of the high-pressure mercury lamp assembly used for photo-treatment of the second surface is 1300 mJ / cm². 2 This setup can reduce the length of the production line by 15%, reduce energy consumption by 50%, and increase unit capacity by 36%.

[0114] In another application scenario, the circuit board includes a composite copper-clad laminate made of Composite EpoxyMaterial-3 (CEM-3), employing... Figure 2 , Figure 3 The coating pre-curing device 12 shown coats and cures the surface. The coating thickness is greater than or equal to 75 μm. The first ultraviolet lamp group 1211 is an LED lamp, and the power density of the LED lamp, used as a surface light source, is 650 mW / cm² during operation. 2 The conveyor chain of the conveyor assembly rotates at 800 r / min, resulting in a pre-curing time of 0.47 s. During the final curing process, the conveyor speed of the second conveyor assembly and the power density of the high-pressure mercury lamp assembly are adjusted to set the light energy density of the high-pressure mercury lamp assembly used for photo-irradiation of the first surface to 1100 mJ / cm². 2 The light energy density of the high-pressure mercury lamp assembly used for photo-treatment of the second surface is 1500 mJ / cm².2 , can make energy consumption reduce 50%, single block independent circuit board production cycle can reduce 60%.

[0115] Different from the prior art, the coating and curing method comprises: performing coating film treatment on the first surface; performing pre-curing treatment on the first surface; performing plate turning treatment on the circuit board; performing coating film treatment on the second surface; and performing final curing treatment on the first surface and the second surface. Through the above manner, the first surface can be pre-cured before the second surface of the circuit board is coated with a coating film, thereby reducing the risk of coating film sagging of the coating film coated on the first surface due to plate turning, and further improving the convenience and coating effect when coating the coating film on the double surfaces of the circuit board arranged opposite to each other.

[0116] It is worth noting that the drawings herein are only used to show the structural relationship and connection relationship of the product of the application, and do not limit the specific structural size of the product of the application.

[0117] The above is only an embodiment of the application, and does not limit the patent scope of the application, and any equivalent structure or equivalent process transformation using the content of the specification and drawings, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the application.

Claims

1. A method of coating and curing a circuit board, characterized by, The circuit board has a first surface and a second surface arranged oppositely, and the coating and curing method comprises: coating the first surface with a paint film; pre-curing the first surface; turning over the circuit board; coating the second surface with a paint film; final curing the first surface and the second surface.

2. The coating curing method according to claim 1, characterized by The step of pre-curing the first surface comprises: turning on a first ultraviolet light group and irradiating the paint film area on the first surface with the first ultraviolet light group.

3. The coating curing method according to claim 2, characterized by The first ultraviolet light group comprises light-emitting diode lamps.

4. The coating curing method according to claim 3, characterized by The pre-curing treatment time is less than or equal to 5s.

5. The method of claim 4, wherein the coating is cured by exposure to ultraviolet light. The ultraviolet light emitted by the light emitting diode lamp is in a wavelength band of 360nm to 370nm, and the power density of the light emitting diode lamp is 480mW / cm 2 -940mW / cm 2 The pre-curing treatment has a treatment time greater than 0.35s and less than or equal to 0.8s.

6. The method of claim 1, wherein, The step of turning over the circuit board comprises: turning over the circuit board in response to the transmittance of the Fourier infrared absorption spectrum of the paint film area on the first surface being greater than or equal to a first predetermined value at an M wave number and being less than or equal to a second predetermined value at an N wave number; the M wave number corresponds to the absorption peak of the C-H bond stretching vibration characteristic of the alkyl chain of the paint film; the N wave number corresponds to the absorption peak of the C=C double bond stretching vibration characteristic of the paint film.

7. The method of claim 1, wherein, The step of final curing the first surface and the second surface comprises: irradiating the paint film area on the first surface and the second surface with a second ultraviolet light group to complete the final curing treatment.

8. The method of claim 7, wherein the curing is performed by, The second ultraviolet light group comprises at least two groups of high-pressure mercury lamps, one group of high-pressure mercury lamps is used to irradiate the paint film area on the first surface, and the other group of high-pressure mercury lamps is used to irradiate the paint film area on the second surface, and the light energy density of the other group of high-pressure mercury lamps is greater than that of the one group of high-pressure mercury lamps.

9. A coating curing system characterized by, The coating and curing system for a circuit board having a first surface and a second surface arranged oppositely comprises: a coating and pre-curing device for sequentially coating the first surface with a paint film, pre-curing the first surface, turning over the circuit board, and coating the second surface with a paint film; a final curing device for final curing the first surface and the second surface.

10. The coating curing system of claim 9, wherein, The coating and pre-curing device comprises: a coating assembly for coating the first surface and the second surface with a paint film; a pre-curing assembly for pre-curing the first surface; a turning over assembly for turning over the circuit board.

11. The coating curing system of claim 9, wherein, The coating and pre-curing device comprises: a first coating machine for coating the first surface with a paint film; a pre-curing assembly for pre-curing the first surface; a turning over assembly for turning over the circuit board; a second coating machine for coating the second surface with a paint film; a first conveying assembly for conveying the circuit board.

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