WO2019214051A1

WO2019214051A1 - Fabrication method for protective layer of printed circuit board

Info

Publication number: WO2019214051A1
Application number: PCT/CN2018/095290
Authority: WO
Inventors: 胡军辉; 王亮亮; 郭冉
Original assignee: 深圳市百柔新材料技术有限公司
Priority date: 2018-05-09
Filing date: 2018-07-11
Publication date: 2019-11-14
Also published as: CN108419378A; CN108419378B; DE112018007569T5

Abstract

A fabrication method for a protective layer of a printed circuit board, comprising the following steps: coating a protective ink on a surface of a circuit board (1) and curing same to form an ink layer (2), wherein the ink layer (2) has a preset open window (201), and the thickness of the ink layer (2) is greater than or equal to 10µm; and then, using a laser engraving machine to remove excess protective ink from the inner edges of the preset open window (201) so as to form a protective layer that has a finely engraved open window (301). The fabrication method for a protective layer of a printed circuit board provided in the present application does not require the use of processes such as exposure and development to fabricate a protective layer, and the technique therefor is thus simple and pollution-free; the utilization ratio of protective ink material is high, the resolution of the open window is high, and the present invention is suitable for the production of various dimensions, such as proofing, small-batch and large-batch production.

Description

Printed circuit board protective layer manufacturing method

Technical field

The present application belongs to the technical field of circuit board manufacturing, and more particularly to a method for manufacturing a printed circuit board protective layer.

Background technique

The printed circuit board is a support for electronic components, referred to as PCB. The PCB usually includes a single layer or a multi-layer circuit. When the circuit layer and the insulating layer on the PCB are fabricated, a protective layer needs to be applied on the surface of the PCB, commonly known as "green oil." The current method for making the protective layer is as follows: silkscreen green oil on the surface of the PCB or a semi-cured green oil is applied to completely cover the PCB, and then the green oil is firmly connected to the surface of the PCB by curing; The excess green oil is then removed by exposure to the wet chemical method used first to form a window. The method is complicated in process and pollutes the water body. The method also requires custom auxiliary materials and equipment, which is costly for small batch production.

technical problem

The purpose of the present application is to provide a method for fabricating a protective layer of a printed wiring board, which aims to solve the technical problem of manufacturing a protective layer by using a wet chemical method of exposure and development in the prior art, which has a complicated process, environmental pollution, and high cost.

Technical solution

The application provides a method for manufacturing a protective layer of a printed circuit board, comprising the following steps:

S10: coating a protective ink on the surface of the circuit board, and curing to form an ink layer, the ink layer has a predetermined opening window, and the thickness of the ink layer is greater than or equal to 10 μm;

S20: removing excess protective ink at the inner edge of the preset window by using a laser engraving machine to form a protective layer with a carved window.

Further, step S10 includes:

Printing and curing the protective ink on the circuit board using an inkjet printer to form a first print layer;

Printing and curing the protective ink on the first printing layer using an inkjet printer to form a second printing layer;

Repeating the above steps until the ink layer is formed;

The thickness of the first print layer, the second print layer to the Nth print layer ranges from 3 μm to 5 μm.

Further, the inkjet printer includes an inkjet head and a radiation source provided on one side of the inkjet head for curing the protective ink.

Further, step S10 includes:

Printing the protective ink onto the circuit board using a screen printing screen;

The ink layer is formed by curing the protective ink using a curing radiator.

Further, the curing radiator includes one or both of a light radiator and a heat radiator.

Further, the light radiator is an ultraviolet curing furnace, and the heat radiator is a mesh belt furnace or an oven.

Further, the resolution of the preset window is greater than 100 μm, and the resolution of the window opening is less than 100 μm.

Further, step S20 includes:

Sending the size information of the circuit board and the carved window to the control module of the laser engraving machine;

An identification module of the laser engraving machine identifies an image of the protective layer applied on the circuit board and transmits it to the control module to compare with the size information to calculate a path of the laser engraving;

The laser head of the laser engraving machine is moved to the edge of the preset window, and the excess protective ink is removed according to the laser engraving path to form the protective layer.

Further, the laser engraving machine includes a control module, an identification module, and a laser head, the identification module is electrically connected to the control module, and the identification module is configured to transmit the acquired information to the control module, A control module is used to control the movement of the laser head.

Further, the laser engraving machine has a lateral resolution of less than or equal to 5 μm, and the laser engraving machine has a longitudinal resolution of less than or equal to 5 μm.

Further, after the step S20, the cleaning ink remaining on the circuit board is further cleaned.

Further, the protective ink is composed of a thixotropic agent and an epoxy resin.

Further, the thixotropic agent is one or more of a hydrogenated castor oil derivative, a polyamide wax, a polyurea, a fumed silica, a bentonite, and an oxidized polyethylene.

Beneficial effect

The manufacturing method of the printed circuit board protective layer provided by the present application has the beneficial effects that the manufacturing method of the printed circuit board protective layer of the present application is first coated and solidified on the surface of the circuit board to form a preset opening window. The ink layer is then taken out by the laser engraving machine to remove the excess protective ink at the inner edge of the preset window to ensure the precision of the window opening. The method does not need to adopt a process such as exposure and development to make a protective layer, and the process is simple and pollution-free, and the ink is protected. The material utilization rate is high, and the resolution of window opening is high, which is suitable for various volume production such as proofing, small batch, and large batch.

DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings used in the embodiments or the prior art description will be briefly described below. Obviously, the drawings in the following description are only the present application. For some embodiments, other drawings may be obtained from those skilled in the art without departing from the drawings.

1 is a flow chart of a method for fabricating a protective layer of a printed circuit board according to an embodiment of the present application;

2 is a schematic structural diagram of a circuit board according to an embodiment of the present application;

3 is a structural view of an ink coating layer provided by an embodiment of the present application;

4 is a structural view of an ink coating layer according to another embodiment of the present application;

FIG. 5 is a structural diagram of a circuit board coated with a protective layer according to an embodiment of the present application.

Among them, the various reference numerals in the figure:

1-circuit board; 11-circuit layer; 2-ink layer; 201-preset window; 21-first print layer; 22-second print layer; 3-protective layer; 301-finished window.

Embodiments of the invention

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clear, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the application and are not intended to be limiting.

It is to be noted that when an element is referred to as being "fixed" or "in" another element, it can be directly on the other element or indirectly. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or indirectly connected to the other element.

It should be understood that the terms "length", "width", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top" The orientation or positional relationship of the "bottom", "inside", "outside" and the like is based on the orientation or positional relationship shown in the drawings, and is merely for convenience of description of the present application and simplified description, and does not indicate or imply the indicated device. Or the components must have a particular orientation, constructed and operated in a particular orientation, and thus are not to be construed as limiting.

Moreover, the terms "first", "second", and the like are used for the purpose of description only, and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, features defining "first" and "second" may include one or more of the features either explicitly or implicitly. In the description of the present application, the meaning of "a plurality" is two or more unless specifically and specifically defined otherwise.

Referring to FIG. 1 to FIG. 5 together, a method for manufacturing a printed circuit board protective layer provided by the present application will now be described. The manufacturing method of the printed circuit board protective layer comprises the following steps:

S10: coating the surface of the circuit board 1 with protective ink, and curing to form an ink layer 2, the ink layer 2 has a predetermined opening window 201, and the thickness of the ink layer 2 is greater than or equal to 10 μm;

S20: removing excess protective ink at the inner edge of the preset window 201 by using a laser engraving machine to form a protective layer 3 having a carved window 301.

The circuit layer 11 and the insulating layer of the circuit board 1 have been completed, and the protective layer 3 protects the surface of the circuit board 1. The carved window 301 on the protective layer 3 exposes the lines on the surface of the circuit board 1 for subsequent soldering, tin plating, and the like.

The manufacturing method of the protective layer of the printed circuit board provided by the present application is compared with the prior art, and the manufacturing method of the protective layer of the printed wiring board of the present application is first coated and solidified on the surface of the circuit board 1 to form the ink having the preset opening window 201. Layer 2, then remove the excess protective ink at the inner edge of the preset window 201 by the laser engraving machine to ensure the precision of window opening. The method does not need to adopt the process of exposure and development to make the protective layer 3, the process is simple, no pollution, and the ink is protected. The material utilization rate is high, and the resolution of window opening is high, which is suitable for various volume production such as proofing, small batch, and large batch.

Further, the resolution of the preset window 201 is greater than 100 μm, and the resolution of the window 301 is less than 100 μm. The ink layer 2 is directly coated on the circuit board 1. Under the limitation of the printing and silk screen technology, the resolution of the preset window 201 is low. In the embodiment, the preset window 201 is carved by a laser engraving machine. The excess protective ink is removed to form a carved window 301 having a resolution of less than 100 μm, which satisfies the precision requirement of the circuit board 1 for the protective layer 3.

Further, the protective ink is composed of a thixotropic agent, an epoxy resin or the like, and a thixotropic network can be formed between the thixotropic molecules, so that the ink has a pseudoplastic or thixotropic substance, and the thixotropic agent can be a hydrogenated castor oil derivative. One or more of a polyamide wax, a polyurea, a fumed silica, a modified material thereof, a bentonite, an oxidized polyethylene, and the like. After the epoxy resin is cured, its long-term heat resistance temperature is above 180oC, so that the ink layer 2 has better heat resistance.

The protective ink has photocuring or heat curing properties, and is rapidly cured under a certain light energy or thermal energy radiation, and the thickness of the protective layer is greater than or equal to 10 μm. The protective ink has the following properties after being completely cured: the breakdown voltage is greater than 1000 V, and the surface hardness is Above 2H, the adhesion to the substrate is greater than 10N. The organic monomer of the small molecule in the protective ink can be connected during the low-temperature photocuring process, and no waste discharge is generated in the subsequent process.

Referring to FIG. 3, in an implementation manner of the printed circuit board protection layer provided by the present application, step S10 includes:

Printing ink is printed and cured on the circuit board 1 using an inkjet printer to form a first printed layer 21;

Printing and curing the protective ink on the first printing layer 21 using an inkjet printer to form a second printing layer 22;

Repeat the above steps until the ink layer 2 is formed;

The thickness of the first printing layer 21, the second printing layer 22 to the Nth printing layer ranges from 3 μm to 5 μm.

Further, an inkjet printer includes an inkjet head and a radiation source. The ink jet head is smaller in size than the wiring board 1, and it is impossible to print the desired ink layer 2 by one-way motion. The printing path of the inkjet head may specifically be: after the inkjet head is printed in the horizontal positive direction, the inkjet head moves a certain distance toward the vertical direction, and then moves the inkjet in the horizontal reverse direction until the single layer printing layer is printed. In the process of inkjet printing, the radiation source illuminates the printed protective ink to cure or semi-cure the ink. After the protective ink of each layer is printed, the protective ink of the layer is correspondingly in the radiation source. Cured or semi-cured under effect. The relative positions of the ink jet head and the radiation source are not limited herein. More specifically, the protective ink is semi-cured under conditions of light irradiation, and the protective ink after the semi-curing is kept in a non-flowing state at 250 ° C or less. It should be noted that the radiation source emits light as an initiation source to cure the ink of each layer, and the radiation source can be UV light or light emitted by a fluorescent lamp such as an LED. Of course, after the ink layer 2 is completely formed, the ink layer 2 can be completely cured by photocuring or heat curing to have high structural strength and insulating electrical properties.

It should be noted that, in this embodiment, the ink layer 2 is composed of the first print layer 21, the second print layer 22, and the Nth print layer 2, where N is an integer greater than or equal to 3. Of course, the ink layer 2 may also be formed by superposing only the first printing layer 21 and the second printing layer 22, in which case, the thickness of the first printing layer 21 and the second printing layer 22 are both 5 μm, and the thickness of the ink layer 2 is It is 10 μm.

Referring to FIG. 4, in another implementation manner of the printed circuit board protection layer provided by the present application, step S10 includes:

Printing the protective ink onto the circuit board 1 using a screen printing stencil;

The ink layer 2 is formed by curing the protective ink using a curing radiator.

In this embodiment, the protective ink is printed on the surface of the wiring board 1 at a time by a screen printing screen, and then the protective ink is cured by a curing radiator to form the ink layer 2. Specifically, when the screen printing screen is printed, the printing head is unidirectionally printed in the horizontal direction, or unidirectionally printed in the vertical direction, and the ink layer 2 is formed in one printing. When the protective ink is cured by the curing radiator, the specific steps are as follows: the circuit board 1 is placed in an optical radiator such as an ultraviolet curing oven, the ink is protected by light, semi-cured, and formed into a non-flowing state, and then the circuit board 1 is placed in the net. In the heat radiator with a furnace or an oven, the protective ink is completely cured.

Referring to FIG. 5, in step S20:

The excess protective ink at the inner edge of the preset opening window 201 is removed using a laser engraving machine to form a sculpted opening window 301.

Wherein the lateral resolution of the laser engraving machine is less than or equal to 5 μm, the longitudinal resolution of the laser engraving machine is less than or equal to 5 μm, thereby ensuring the precision of laser engraving, so that the precision of the engraving window 301 satisfies the design requirements.

Step S20 includes:

Sending the size information of the circuit board 1 and the carved window 301 to the control module of the laser engraving machine;

The identification module of the laser engraving machine identifies the image of the ink layer 2 coated on the circuit board 1, and transmits it to the control module to compare with the size information to calculate the path of the laser engraving;

The laser head of the laser engraving machine is moved to the edge of the preset window 201, and the excess protective ink is removed according to the laser engraving path to form the protective layer 3.

The laser engraving machine comprises a control module, an identification module and a laser head. The identification module is electrically connected with the control module. After the information acquired by the identification module is transmitted to the control module, the control module can calculate the movement path of the laser head according to the information, and control the laser. The movement of the head. Specifically, when the circuit board 1 is placed under the laser engraving machine, the identification module of the laser engraving machine takes a picture of the image of the circuit board 1 and the ink layer 2, and sends the taken photo to the control module, and after the control module analyzes, Comparing the size information of the circuit board 1 in the photo information with the pre-stored size information of the circuit board 1, and positioning the position of the engraving window 301 by the size information of the pre-stored engraving window 301, and calculating the laser head carving The path is then moved to the top of the preset window 201, and the excess protective ink is removed in accordance with its calculated path motion to form the protective layer 3.

After step S20:

The manufacturing method of the printed circuit board protective layer further comprises cleaning the residual protective ink on the circuit board to remove the waste ink remaining after the laser burning, thereby further improving the surface quality of the circuit board. Of course, after the step S20, the steps of tin plating, soldering, etc. may be included, which are not limited herein.

The above is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection of the present application. Within the scope.

Claims

The manufacturing method of the printed circuit board protective layer is characterized in that the method comprises the following steps:

S10: coating a protective ink on the surface of the circuit board, and curing to form an ink layer, the ink layer has a predetermined opening window, and the thickness of the ink layer is greater than or equal to 10 μm;

S20: removing excess protective ink at the inner edge of the preset window by using a laser engraving machine to form a protective layer with a carved window.
The method of manufacturing a protective layer of a printed wiring board according to claim 1, wherein the step S10 comprises:

Printing and curing the protective ink on the circuit board using an inkjet printer to form a first print layer;

Printing and curing the protective ink on the first printing layer using an inkjet printer to form a second printing layer;

Repeating the above steps until the ink layer is formed;

The thickness of the first print layer, the second print layer to the Nth print layer ranges from 3 μm to 5 μm.
A method of manufacturing a printed wiring board protective layer according to claim 2, wherein said ink jet printer comprises an ink jet head and a radiation source provided on one side of said ink jet head for curing the protective ink.
The method of manufacturing a protective layer of a printed wiring board according to claim 1, wherein the step S10 comprises:

Printing the protective ink onto the circuit board using a screen printing screen;

The ink layer is formed by curing the protective ink using a curing radiator.
The method of fabricating a protective layer of a printed wiring board according to claim 4, wherein the curing radiator comprises one or both of a light radiator and a heat radiator.
The method of manufacturing a printed wiring board protective layer according to claim 5, wherein the light radiator is an ultraviolet curing furnace, and the heat radiator is a mesh belt furnace or an oven.
The method for manufacturing a protective layer of a printed wiring board according to claim 1, wherein the resolution of the predetermined window is greater than 100 μm, and the resolution of the window is less than 100 μm.
The method of manufacturing a protective layer of a printed wiring board according to claim 1, wherein the step S20 comprises:

Sending the size information of the circuit board and the carved window to the control module of the laser engraving machine;

An identification module of the laser engraving machine identifies an image of the protective layer applied on the circuit board and transmits it to the control module to compare with the size information to calculate a path of the laser engraving;

The laser head of the laser engraving machine is moved to the edge of the preset window, and the excess protective ink is removed according to the laser engraving path to form the protective layer.
The method of manufacturing a printed circuit board protective layer according to claim 1, wherein the laser engraving machine comprises a control module, an identification module, and a laser head, wherein the identification module is electrically connected to the control module, and the identification A module is operative to communicate the acquired information to the control module, the control module for controlling movement of the laser head.
The method of manufacturing a printed wiring board protective layer according to claim 1, wherein the laser engraving machine has a lateral resolution of less than or equal to 5 μm, and the laser engraving machine has a longitudinal resolution of less than or equal to 5 μm.
The method of manufacturing a printed wiring board protective layer according to claim 1, further comprising, after step S20, cleaning the protective ink remaining on the wiring board.
A method of fabricating a protective layer for a printed wiring board according to claim 1, wherein said protective ink is composed of a thixotropic agent and an epoxy resin.
The method of manufacturing a printed wiring board protective layer according to claim 11, wherein the thixotropic agent is hydrogenated castor oil derivative, polyamide wax, polyurea, fumed silica, bentonite, and oxidation. One or more of the polyethylenes.