CN115835518A - Method for manufacturing solder mask of thick copper circuit board - Google Patents

Abstract

The invention discloses a method for manufacturing a solder mask of a thick copper circuit board, which comprises the following steps: s10: providing a thick copper-clad plate, firstly manufacturing a first etching circuit, then manufacturing a second etching circuit, and integrally forming the etching circuit; s20: using a screen to screen print the first solder mask layer, transferring and curing the pattern, and polishing; s30: spraying a second solder mask layer and a third solder mask layer; s40: processing the whole solder mask pattern to form a solder mask layer of the thick copper circuit board; through redesigning the thick copper circuit, secondary circuit etching is formed, the direct fall of the circuit is reduced, printing ink is printed on the fall in a silk screen mode and solidified and polished, a solder mask ink layer is formed through side ink pattern manufacturing, pre-spraying and main spraying, the idea and the method that the manufacturing problem of the solder mask layer of the thick copper circuit board is improved through simply increasing the thickness of the printing ink are changed, the using amount of the printing ink is reduced, the solder mask reliability is improved, and the problem of oil accumulation at the edge of the circuit board is avoided by utilizing a nail plate structure in the spraying process.

Description

Method for manufacturing solder mask of thick copper circuit board

Technical Field

The invention relates to the field of circuit boards, in particular to a method for manufacturing a rigid-flex printed circuit board and the rigid-flex printed circuit board.

Background

For some electronic modules needing to bear larger current, such as new energy automobiles, charging piles, power modules and the like, a circuit board with thicker copper is needed, the circuit board with the copper thickness larger than 70 μm is generally called a thick copper circuit board, and the thick copper circuit board has the characteristics of good large current carrying, high heat dissipation, strong support and the like.

Because the thick copper circuit board has thick copper, the difference formed by the side edge of the etched circuit and the board surface is large, and ink is not easy to cover the circuit when a solder mask is manufactured, so that the problems of over-thin ink, red circuit and the like are easily generated, and the appearance and the performance of the circuit board are influenced.

At present, there are many techniques for a solder resist processing process of a thick copper circuit board, for example, patent document 1 is cited: the Chinese invention patent application, a solder resist process for a PCB (publication No. CN114364151A; published No. 4/15/2022), discloses a method for manufacturing a solder resist layer of a thick copper plate by adopting a method of ' solder resist → solder resist imaging → post-baking solder resist → secondary solder resist imaging → secondary solder resist post-baking → character printing ', and further discloses ' the solder resist comprises the following steps: primary spraying: spraying on two sides of the plate; standing for the first time: standing the plate until bubbles dissipate; secondary spraying: spraying on two sides of the plate again; and (3) secondary standing: standing the plate until bubbles dissipate; pre-baking: putting the plate into an oven for pre-baking, and carrying out secondary solder mask printing, wherein the method comprises the following steps: and (3) third spraying: spraying on two sides of the plate again; standing for the third time: standing the plate until bubbles dissipate; secondary pre-drying: putting the plate into a baking oven for pre-baking; however, this technique only adopts the basic mode of increasing the ink thickness by multiple spraying and multiple standing, and in the actual manufacturing process, multiple spraying and multiple standing can solve the problems of too thin solder mask layer, red circuit and the like of the thick copper plate, but because the structure of the thick copper circuit is not changed and the ink covers the thick copper circuit layer as much as possible, the problem of too thick ink thickness is easily caused, and the problems of oil accumulation, uneven ink, impression of exposure and the like are generated.

For another example, patent document 2 is cited: the Chinese invention patent application, a thick copper surface solder resist ink processing technology (publication No. CN114364150A; published: 2022, 4/15), discloses that the first low-pressure spraying → partial exposure → the second low-pressure spraying → normal exposure → screen printing ink → normal processing is adopted, and further discloses that the thickness of the ink formed by the low-pressure pre-spraying is 70-90 μm; the method is also common repeated solder resist ink processing, only a screen printing mode is replaced by secondary spraying, and the formed ink is thick and can also generate the problems of oil accumulation, uneven ink, exposure indentation and the like.

For another example, patent document 3 is cited: the Chinese invention patent application discloses a manufacturing method of a thick copper plate with a sprayed and silk-screen double-layer solder mask layer (publication number: CN112118685A; published date: 12 and 22 2020), and discloses a processing process of adopting solder mask spraying → first prebaking → first exposure, developing → low-temperature baking → surface roughening → solder mask silk-screen → vacuumizing → second prebaking → second exposure, developing → high-temperature baking and curing; the method adopts a manufacturing mode of combining spraying and silk-screen printing, controls the processing times of the solder resist ink to be twice, but the essence of the method is the same as that of the cited patent document 2, and increases the thickness of the ink through a technical method, thereby realizing the increase of the thickness of the solder resist ink layer of the thick copper plate.

For another example, patent document 4 is cited: the Chinese invention patent application, a printing method of a thick copper plate (publication number: CN110831345A; published: 21.2.2020), discloses the steps of manufacturing a circuit → screen printing solder resist ink → exposing the side of the circuit → manufacturing a solder resist layer → manufacturing a post-process; the method uses the method of firstly manufacturing the side ink of the thick copper circuit and then manufacturing the whole solder resist ink, the processing technology is relatively simple, but because the pattern of the thick copper circuit is changed, the essence of the silk-screen printing ink layer is not changed, no matter how to silk-screen the solder resist layer, the ink meets the side edge of the thick copper circuit and forms extrusion with the screen printing plate, the problems of over-thin ink and red line can be generated, and if the silk-screen printing quantity of the ink is increased, the problems of ink accumulation, uneven solder resist and the like can be generated by reverse falling.

For the above 4 cited patent documents and other examples, the solder resist ink layer is manufactured by spraying, and it is also necessary to prevent the problem of oil accumulation at the edge of the board due to the umbrella shape of the ink when spraying, and the problem of subsequent ink contamination of the board surface, film contamination, poor exposure, etc. caused by the oil accumulation at the edge of the board due to the umbrella shape of the ink when spraying to the edge of the circuit board.

Based on the above background and problems, it is desirable to provide a manufacturing method capable of effectively improving the quality of the solder mask layer of the thick copper circuit board.

Disclosure of Invention

The invention mainly aims to provide a method for manufacturing a solder mask layer of a thick copper circuit board, and aims to solve the problems that in the prior art, solder mask ink of the thick copper circuit board is printed or sprayed excessively thick, ink is accumulated, or ink is formed at the edge of the top end of a copper layer circuit to cover excessively thin, the circuit becomes red, and oil is accumulated at the edge of the board in the spraying processing process.

In order to achieve the purpose, the invention provides a method for manufacturing a solder mask layer of a thick copper circuit board, which is characterized by comprising the following steps:

s10: providing a thick copper-clad plate, wherein the thick copper-clad plate comprises a circuit copper layer and a substrate layer, a first etching circuit is firstly manufactured on the thick copper-clad plate, then a second etching circuit is manufactured, and the first etching circuit and the second etching circuit form an etching circuit integrally;

s20: silk-screening the first solder mask layer on the etching circuit by using a screen printing plate, and performing pre-curing → exposure → development → baking and curing → polishing processing to form a circuit board to be sprayed;

s30: spraying a second solder mask layer on the circuit board to be sprayed, and then spraying a third solder mask layer to form a circuit board to be subjected to solder mask processing;

s40: and carrying out integral resistance welding pattern processing on the circuit board to be subjected to resistance welding processing to form the thick copper circuit board resistance welding layer.

Furthermore, the thickness of the circuit copper layer is larger than or equal to 105 mu m.

Further, the method for fabricating the first etching line first comprises: performing single-side pre-reduction adjustment on the circuit pattern in the set design data, and performing first pattern transfer processing to form the first etching circuit; the first pattern transfer processing process is to paste a dry film on the circuit copper layer, and then carry out exposure → development → etching → film removal; the etching thickness of the first etching line is 1/2 to 1/3 of the copper layer of the line.

Further, the method for fabricating the second etching line includes: performing a second pattern transfer process according to the circuit pattern in the predetermined design data to form the second etching circuit; integrally forming the etched circuit after processing; the second pattern transfer processing process is to coat a wet film layer on the circuit board of the first etching circuit, and then carry out exposure → development → etching → film removal; the etching thickness of the second etching line is the thickness of the line copper layer after the first etching line is etched.

Optionally, the method for fabricating the first etching line first includes: selecting the thick copper-clad plate which is larger than the circuit copper layer specified by the established design data by a certain thickness in advance, and manufacturing a circuit guide groove on the circuit copper layer; the circuit guiding groove is formed by arranging a fine circuit pattern with the width smaller than the set line width to be etched at the middle position of the line width of the surface of each circuit pattern in the set design data, and then performing whole plate dry film attaching → exposure → development → etching → film removing.

Optionally, the method for fabricating the second etching line again includes: performing a second pattern transfer process according to the width of the circuit pattern in the predetermined design data to form a second etched circuit; and integrally forming the etched line after processing.

Furthermore, the screen printing plate is a point blocking screen plate, and a side edge area of the etching circuit corresponding to the point blocking screen plate is a blank screen gauze area.

Further, the pre-curing → exposure → development → bake curing → sanding process is: the curing parameters of the pre-curing are multiplied by 75 ℃ for 30min to 45min; the exposure is carried out by pre-enlarging the second etching line by 10-50 mu m according to the pattern of the second etching line; the baking and curing step is to completely cure the ink by using the parameters of 150 ℃ multiplied by 60min to 90 min; and the polishing is performed by using a nylon polishing brush or a non-woven fabric polishing brush.

Further, the second solder mask is sprayed in advance by adopting a low-pressure spraying method, and the thickness of the second solder mask formed by spraying in advance is 5.0-10.0 μm; and the second solder mask is sprayed by adopting a low-pressure spraying method, wherein the thickness of the third solder mask formed by the main spraying is 15-40 mu m.

Further, the low pressure spraying adopts the fixed spraying of nail board support, the fixed spraying of nail board support is: s310: manufacturing a nail plate supporting hole in the invalid area of the circuit board to be sprayed; s320: manufacturing a nail plate, wherein the nail plate is manufactured by arranging nail heads on a light plate, the nail heads are distributed corresponding to the support holes, the maximum diameter of a cylinder of the nail heads is larger than that of the support holes, and two sides of the nail plate along the advancing direction of the low-pressure spraying are provided with clamp avoiding grooves; s330: and placing the circuit board to be sprayed on the nail plate, setting the transportation width of low-pressure spraying equipment to be the width of the nail plate, and performing low-pressure spraying.

According to the technical scheme, the copper layer circuit is redesigned compared with the original set design data and is reprocessed to form secondary circuit etching, so that the direct fall of the circuit is reduced, the circuit forms a buffered side structure under the condition of not reducing the thickness of the circuit, then a solder resist ink layer is formed by manufacturing a side ink pattern, pre-spraying and main spraying, and a mode of combining circuit pattern adjustment and solder resist layer structure adjustment is formed in the manufacturing process, so that the idea and the method for improving the manufacturing problem of the solder resist layer of the thick copper circuit board by simply increasing the thickness of the ink are changed, the covering thickness and the processing precision of the solder resist layer can be effectively ensured while the consumption of the ink and the thickness of the ink are controlled, and the processing reliability of the solder resist layer of the thick copper circuit board is improved; in the spraying process, utilize nail board structure, under the circumstances of guaranteeing the smooth transportation of circuit board, the false increase circuit board area has effectively avoided the problem of circuit board flange oil gathering, promotes the processing quality.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

FIG. 1 is a schematic process flow diagram of a method for manufacturing a solder mask layer of a thick copper circuit board according to the present invention;

FIG. 2 is a schematic diagram of a first etching process for manufacturing a solder mask layer of a thick copper circuit board according to the method of the present invention;

FIG. 3 is a schematic diagram of a second etching process for manufacturing a solder mask layer of a thick copper circuit board according to the method of the present invention;

FIG. 4 is a schematic diagram of a third etching process for fabricating a solder mask layer of a thick copper circuit board according to the method of the present invention;

FIG. 5 is a schematic diagram of a first solder mask manufacturing process of the method for manufacturing a solder mask of a thick copper circuit board of the present invention;

FIG. 6 is a schematic diagram of a second solder mask layer and a third solder mask layer manufactured by the method for manufacturing a solder mask layer of a thick copper circuit board according to the present invention;

FIG. 7 is a schematic view of a low-pressure spraying process for manufacturing a solder mask of a thick copper circuit board according to the method of the present invention;

FIG. 8 is a schematic diagram of a low-pressure spraying process for manufacturing a solder mask of a thick copper circuit board according to the method of the present invention;

fig. 9 is a schematic structural diagram of a thick copper circuit board solder mask layer of the thick copper circuit board solder mask layer manufacturing method of the invention.

The reference numbers illustrate:

the implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that all directional indicators (such as up, down, left, right, front, and back \8230;) in the embodiments of the present invention are only used to explain the relative positional relationship between the components, the motion situation, etc. in a specific posture (as shown in the attached drawings), and if the specific posture is changed, the directional indicators are changed accordingly.

In addition, the descriptions related to "first", "second", etc. in the present invention are only for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

Referring to fig. 1, fig. 1 is a schematic process flow diagram of a method for manufacturing a solder mask layer of a thick copper circuit board according to the present invention; FIG. 1 shows a basic process flow of a method for manufacturing a solder mask layer of a thick copper circuit board according to the present invention; the process for manufacturing the etching line comprises the following steps:

referring to fig. 2, fig. 2 is a schematic diagram illustrating a first etching process for fabricating a solder mask layer of a thick copper circuit board according to the method of the present invention;

the thick copper plate is a circuit board with the copper thickness being more than or equal to 70 mu m, but the manufacturing of a solder mask layer of the circuit board with the copper thickness being 70 mu m to 105 mu m (namely 2OZ to 3 OZ) does not have too large technical problem basically at present; the present embodiment is described by taking the example that the thickness of the copper layer of the circuit is larger than or equal to 105 μm.

Fig. 2 is a schematic view of a process for etching a line a (30A), which comprises:

s10: the method comprises the steps of providing a thick copper clad laminate A (20A), wherein the thick copper clad laminate A (20A) comprises a circuit copper layer A (210A) and a substrate layer A (220A), firstly manufacturing a first etching circuit A (310A) on the thick copper clad laminate A (20A), then manufacturing a second etching circuit A (320A), and integrally forming an etching circuit (30A) by the first etching circuit A (310A) and the second etching circuit A (320A).

Fig. 2 includes fig. 2a, fig. 2b, fig. 2c, fig. 2d, fig. 2e, fig. 2f, which form a process diagram of the whole process for manufacturing the first etching line.

Wherein, fig. 2a is a thick copper clad laminate a (20A), a circuit pattern is made on the thick copper clad laminate a (20A), the circuit pattern in the established design data in the thick copper clad laminate a (20A) is subjected to unilateral pre-reduction adjustment, and then the first pattern transfer processing is carried out to form a first etching circuit a (310A); as shown in fig. 2b, the schematic diagram of the dry film pasting layer a (230A) → exposure → development process after the pre-fine adjustment of the pattern; as shown in fig. 2c, a schematic view of a process of forming a first etching line a (310A) by a first etching is shown; that is, fig. 2a to 2c show a first pattern transfer process, i.e., a process of applying a dry film layer a (230A) to the wiring copper layer a (210A) → followed by exposure → development → etching → de-lamination; the first etching line A (310A) has an etching thickness of 1/2 to 1/3 of the line copper layer A (210A).

The method for fabricating the second etching line a (320A) in S10 includes: performing a second pattern transfer process according to the circuit pattern in the predetermined design data to form a second etched circuit A (320A); integrally forming an etched circuit A (30A) after processing; as shown in fig. 2d, the second pattern transfer process is to entirely coat the wet film layer a (330A) on the circuit board of the first etched circuit a (310A), as shown in fig. 2e, and then perform exposure → development, as shown in fig. 2f, and then perform etching → de-lamination, so as to form the etched circuit a (30A) as a whole; the second etched line a (320A) has an etched thickness of the line copper layer a (210A) after the first etched line a (310A) is etched away.

In the first etching line manufacturing method, the line pattern of the thick copper plate is divided into two layers in the longitudinal structure, and is etched and processed respectively to form the integral etching line a (30A) consisting of the first etching line a (310A) and the second etching line a (320A), because the line width of the thick copper plate is generally wide, the line width is not less than 100 μm under general conditions if the copper thickness is not less than 105 μm (because the designed width is narrow, the problem of high aspect ratio of line etching is easy to generate during pattern transfer, the line etching is difficult to realize, the circuit board application is not beneficial, the problems of line breaking, line burning and the like are easy to occur during application), when the first etching line a (310A) is used for pattern manufacturing, a pre-small adjustment mode is selected (generally, the single-side pre-small distance is 30 μm to 75 μm), the line pattern is narrowed to a certain degree, then pattern etching is performed, only 1/2 to 1/3 of the integral copper thickness is etched, and a first layer of the first etching line is provided; when the second etching line A (320A) is processed, a wet film is needed to protect the first etching line A (310A) to prevent the problem that the copper thickness of the first etching line A (310A) does not reach the standard due to secondary etching, the wet film can form all-around protection on three sides of the line, then normal figures are used for secondary etching processing to form the second etching line A (320A), a second step is given to the lower layer of the line, and the lateral etching phenomenon of the line can occur during etching, so that the line formed by the secondary etching is equivalent to two step lines, or (when the first etching line A (310A) and the second etching line A (320A) are staggered slightly) to form a step line, but the slope of the side edge of the line is increased, when the first solder mask is manufactured subsequently, effective coverage or 'climbing' coverage effect can be formed at the corner position and the side face of the line, a better adhesion basic effect can be given to the second solder mask layer and the third solder mask layer, and therefore the ink thickness and coverage effect of the thick line can be ensured, and the copper plate can be covered effectively, and the copper plate can be covered by the copper plate, and the copper plate can be effectively controlled by the solder mask.

Referring to fig. 3, fig. 3 is a schematic diagram illustrating a second etching process for fabricating a solder mask layer of a thick copper circuit board according to the method of the present invention.

In one embodiment, the second method for fabricating etched lines in fig. 3 is still performed according to the step S10, but the specific fabrication method is different from the first method for fabricating etched lines, and the specific fabrication method is as follows:

the method for manufacturing the first etching circuit comprises the following steps: selecting a thick copper clad laminate B (20B) which is larger than a circuit copper layer specified by established design data by a certain thickness (the thick copper clad laminate B (20B) comprises a circuit copper layer B (210B) and a substrate layer B (220B)), manufacturing a circuit guide groove B (240B) on the circuit copper layer B (210B), wherein the circuit guide groove B (240B) is a first etching circuit;

the circuit guiding groove B (240B) is formed by providing a fine circuit pattern with a width smaller than a predetermined line width to be etched at a middle position of the line width on the surface of each circuit pattern in predetermined design data, attaching a dry film layer B (230B) on the whole board as shown in fig. 3a, exposing → developing → etching as shown in fig. 3B, and removing the film (not shown).

The method for fabricating the second etching line B (30B) further comprises: performing a second pattern transfer process according to the width of the circuit pattern in the predetermined design data to form a second etched circuit B (30B); after processing, the whole etching circuit is formed, and the etching circuit is provided with a circuit guide groove B (240B) (namely a first etching circuit).

According to the second manufacturing method of the etched circuit, the circuit guide groove B (240B) is manufactured in the center of the top end of the circuit of the thick copper plate, in the second etching process, a central recess is formed in the circuit top layer of the circuit guide groove B (240B), when the first solder mask is manufactured subsequently, a basic ink layer can be formed on the side face of the circuit, a layer of ink can be covered on the recess position to form an ink base in the central area of the top layer of the circuit, the manufacturing bases of the second solder mask and the third solder mask are formed, the combination effect of the ink of the second solder mask and the third solder mask can be improved by utilizing the similar intermiscibility principle of the ink, and the problem that the ink at the corner position of the circuit is formed by measuring flow after the ink is manufactured is solved; however, the circuit guiding groove B (240A) is only present on the circuit, and for the copper sheet region which needs to be soldered with components and has a supporting property, it is necessary to determine whether to design the circuit guiding groove B (240B) according to actual conditions so as not to affect the soldering performance or reliability.

When the circuit guiding groove B (240B) is manufactured, the circuit copper layer B (210B) of the thick copper clad laminate B (20B) with a certain thickness larger than the original circuit copper layer is used for manufacturing, and if the circuit copper layer with the original thickness is adopted for manufacturing, after the second circuit etching, the liquid medicine is exchanged frequently in the circuit guiding groove B (240B), so that the problem that the circuit copper thickness is etched excessively and does not reach the standard is caused; the thickness is generally 10 to 20 μm larger, which provides a thickness basis for etching the circuit guiding groove B (240B) and can prevent the second circuit etching from influencing the copper layer circuit through the circuit guiding groove B (240B); after the pre-enlarging, during the second circuit etching, the etching parameters (etching time, etching spraying pressure, etching thickness, etc.) need to be adjusted according to the pre-enlarging to ensure the copper thickness of the circuit to reach the standard, and the depth of the circuit guiding groove B (240B) formed after the etching is generally 5 μm to 25 μm, and the width is generally 10 μm to 40 μm.

Referring to fig. 4, fig. 4 is a schematic diagram illustrating a third etching process for fabricating a solder mask layer of a thick copper circuit board according to the method of the present invention.

In one embodiment, in combination with the above-mentioned first method for fabricating an etched circuit and the second method for fabricating an etched circuit, there is also a third method for fabricating an etched circuit; the third method for fabricating etched lines in fig. 4 is still performed according to the step S10, but the specific fabrication method is different from the first method for fabricating etched lines and the second method for fabricating etched lines, and the specific fabrication method includes:

the method for manufacturing the first etching circuit comprises the following steps: first, in the same manner as in the case of manufacturing the wire guide groove B (240B) by the method for manufacturing the second etching wire, a wire guide groove C (240C) is manufactured (as shown in fig. 4a and 4B), then, in the same manner as in the case of manufacturing the first etching wire a (310A) and the second etching wire a (320A), a first etching wire C (310C) and a second etching wire C (320C) are manufactured, and finally, an etching wire C (30C) is formed, and after etching is performed 3 times in total, the wire guide groove C (240C), the first etching wire C (310C), and the second etching wire C (320C) are sequentially manufactured; at this time, the first etched line C (310C) includes both the line guide groove C (240C) and the first-layer etched line.

The third method for manufacturing etched circuit substantially combines the circuit guiding groove B (240B) of the second method for manufacturing etched circuit with the first etched circuit a (310A) and the second etched circuit a (320A) of the first method for manufacturing etched circuit to form a circuit pattern of the first etched circuit and the second etched circuit which not only comprise the circuit guiding groove, but also comprise two layers of ladder circuits.

In order to describe the subsequent manufacturing technique more simply and clearly, the following will select the etched circuit C (30C) (including the circuit guiding groove C (240C), the first etched circuit C (310C), and the second etched circuit C (320C)) as the further explanation basis of the technique; the process and effects of the etched line C (30C) described below are the same as those of the etched line a (30A) or the etched line B (30B).

Referring to fig. 5, fig. 5 is a schematic diagram of a process of fabricating a first solder mask layer according to a method for fabricating a solder mask layer of a thick copper circuit board of the present invention; fig. 5 includes the following fabrication steps:

s20: silk-screening the first solder mask layer (510) of the etched circuit C (30C) by using a screen (40) (as shown in FIG. 5 a), and performing pre-curing → exposure → development → baking curing → grinding processing to form a circuit board to be sprayed (as shown in FIG. 5 b); the screen is a blocking point screen (40), the side area of the etching circuit corresponding to the blocking point screen is a blank screen area (410), and the rest areas are blocking point areas (420).

The screen plate with the blocking points, namely, photosensitive paste is printed on the screen, a film exposure pattern is used for transferring, then a non-exposure area is washed away, a screen plate with a blank screen area and the blocking point area is formed, the area needing printing ink (oil) is a blank screen area (410) with a window, and the area without printing ink (oil) is the blocking point area; in this embodiment, the first solder mask layer (510) needs to cover the side of the etched circuit C (30C) and the top circuit guiding groove C (240C) (the top circuit guiding groove C (240C) needs less ink to cover, and the margin of the screen printing ink can be used to meet the filling requirement), so that the ink needs to meet the requirement of the side of the thick copper circuit as much as possible, and the effect of using the ink to firstly reduce the fall of the side of the circuit copper layer and firstly meet the ink covering of the side of the thick copper circuit is achieved, therefore, the design range of the blank screen printing area (40) is that the ink is only put under the side of the circuit, the design range of the blank screen printing area (410) is that the blank screen printing ink covers the edge from the top to the bottom of the etched circuit C (30C) and is respectively enlarged by 10 μm to 35 μm towards both sides, after the screen printing, the ink is that the ink is attached to the side of the circuit and partially attached to the top of the circuit, the basic solder mask layer of the first solder mask layer (510) is formed, and the basic solder mask layer is used as the ink base for the subsequent manufacturing of the second solder mask layer and the third solder mask layer; the etched circuit C (30C) is a circuit with a side step circuit or a slope surface with larger buffer, and the first solder mask layer (510) is easier to cover the side surface of the circuit; the mesh number of the screen (40) can be selected from 40T, 43T or 77T according to requirements.

And, among them, the pre-curing → exposure → development → bake curing → grinding process is: the curing parameter of the pre-curing is 75 ℃ multiplied by 30min to 45min, the exposure is carried out by pre-enlarging 10 mu m to 50 mu m according to the graph of the second etching line C (320C), the baking curing is carried out by completely curing the ink by using the parameter of 150 ℃ multiplied by 60min to 90min, and the polishing is carried out by using a nylon brush or a non-woven fabric brush.

Carrying out pattern transfer processing on the first solder mask layer (510), wherein during exposure, a pre-large film is adopted, a film light-transmitting area can cover the surface of a circuit and the expectation of the side edge of the circuit to form ink exposure of the surface and the side edge of the circuit, curing and baking are carried out, and then polishing is carried out, on one hand, the polishing is carried out in order to remove an ink layer which is still attached insecurely after curing, so that the adhesion force and the adhesion effect of a subsequent second solder mask layer and a third solder mask layer are prevented from being influenced by the insecurely ink layer, on the other hand, a relatively rough surface is given to the first solder mask layer (510), so that the bonding force of the subsequent solder mask layer is stronger; during grinding, a soft nylon grinding brush or a soft non-woven cloth grinding brush with the Shore hardness A of 25, 35 or 45 can be used, the mesh number of the nylon grinding brush can be 800 meshes, 1000 meshes or 1200 meshes, the non-woven cloth grinding brush can also be 800# or 1000# or 1200# in granularity, and the first solder mask layer (510) is prevented from being excessively ground.

First solder mask (510) can select for use the printing ink the same with second solder mask and third solder mask colour, also can select for use colorless transparent printing ink, but can not select for use the printing ink different with second solder mask and third solder mask colour, also can not select for use the mute printing ink, avoids producing the printing ink performance and does not match or the printing ink colour difference, influences processing and outward appearance.

Referring to fig. 6, fig. 6 is a schematic diagram illustrating a second solder mask layer manufactured by the method for manufacturing a solder mask layer of a thick copper circuit board according to the present invention; fig. 6 includes the following fabrication steps:

s30: spraying a second solder mask layer (520) on the circuit board to be sprayed (shown in figure 6 a), and then spraying a third solder mask layer (530) (shown in figure 6 b) to form a circuit board to be subjected to solder mask processing; in the embodiment, the second solder mask layer (520) is sprayed and pre-sprayed by a low-pressure spraying method to form a thickness of 5.0-10.0 μm; and spraying a third solder mask layer (530) by adopting a low-pressure spraying method to carry out main spraying, wherein the formed thickness is 15-40 mu m.

Because the first solder mask layer (510) is manufactured as the base layer, and the second solder mask layer (520) and the third solder mask layer (530) are manufactured in a spraying mode, the adhesion effect of the ink can be ensured, the silk-screen thickness of a silk-screen area of the ink does not need to be controlled in a silk-screen mode, and the processing efficiency can be effectively improved by spraying processing; in the embodiment, low-pressure spraying is adopted instead of electrostatic spraying, the low-pressure spraying is realized by directly spraying ink on the surface of the circuit board by adopting air pressure, and the intersecting electrostatic spraying has the characteristics of less oil consumption, lower equipment cost (no need of a complex electrostatic generation and electrostatic guiding device, no need of a complex high-precision spray cup, a high-precision mechanical combination device and the like), safer processing and more efficient spraying.

In the embodiment, the low-pressure spraying adopts a processing mode of pre-spraying and main spraying, the spraying air pressure of the pre-spraying is small, the amount of the spraying ink is small, a thin ink layer is sprayed on the board surface firstly by using a pre-spraying head (610), the effects similar to 'soaking' and 'guiding' ink layer are achieved, a 'mild' environmental condition which is more beneficial to solder resistance of the adhesion of the ink layer is provided for the board surface, and the main spraying is used for using a main spraying head (620) to solder the ink layer to be sprayed to the required thickness, so that the covering process of the ink of the solder resistance layer is completely finished.

Since different low-pressure spraying equipment has different parameter configurations, and no unified low-pressure spraying parameter standard exists at present, in the embodiment, only the thickness formed by spraying is used as the setting basis of the spraying parameters, namely, the thickness of the second solder mask layer (520) formed by pre-spraying is 5.0-10.0 μm, and the thickness of the third solder mask layer (530) formed by main spraying is 15-40 μm; as a reference, the spraying parameters of the pre-spraying can be set as follows: ink viscosity ISO viscosity cup (3 mm): 30 seconds to 40 seconds; spraying air pressure: 0.10MPa to 0.20MPa; pre-large spraying unilateral size: the single side is 7cm to 15cm larger than the width of the circuit board; the spraying parameters of the main spraying can be set as follows: ink viscosity ISO viscosity cup (3 mm): 50 seconds to 90 seconds; spraying air pressure: 0.16MPa to 0.42MPa; pre-large spraying unilateral size: the single side is larger than 7cm to 15cm of the width of the circuit board.

Referring to fig. 7 and 8, fig. 7 is a schematic flow chart of a low-pressure spraying manufacturing process of a method for manufacturing a solder mask layer of a thick copper circuit board according to the present invention; FIG. 8 is a schematic diagram of a low-pressure spraying process for manufacturing a solder mask of a thick copper circuit board according to the method of the present invention.

The low-pressure spraying is supported and fixed by the nail plate (70), referring to fig. 8base:Sub>A and 8b (fig. 8b isbase:Sub>A schematic view ofbase:Sub>A cross-sectional structurebase:Sub>A-base:Sub>A of fig. 8base:Sub>A), the nail plate (70) is supported and fixed by:

s310: manufacturing a nail plate supporting hole (810) in an invalid area of the circuit board (80) to be sprayed;

s320: manufacturing a nail plate (70), wherein the nail plate (70) is manufactured by arranging a nail head (710) on a light plate, and the arrangement can be adhesion fixing, insertion fixing and the like, so that the nail head is ensured to be stable and firm and not to shift or deform in the processing process; the nail heads (710) are distributed corresponding to the support holes (810), the maximum diameter of the columns of the nail heads (710) is larger than that of the support holes (810), and clamp avoiding grooves (720) are formed in the two sides of the nail plate (70) along the advancing direction of low-pressure spraying;

s330: and placing the circuit board (80) to be sprayed on the nail plate (70), setting the transportation width of the low-pressure spraying equipment to be the width of the nail plate (70), and performing low-pressure spraying.

Because a thick copper circuit board needs to be sprayed and processed, relative to a circuit with a common copper thickness, relatively more ink needs to be sprayed, although a first solder mask layer (510) is taken as a base, the characteristic problem of spraying still needs to be noticed, because the ink generally takes the shape of an umbrella after coming out of an oil spraying port during spraying, the ink spraying needs to cover the whole board surface, therefore, the umbrella-shaped ink needs to spray a part of the ink to the outside of the board surface so that (at least) the center of the umbrella-shaped ink can advance to the edge of the board, thereby realizing the full coverage of the umbrella-shaped ink on the sprayed circuit board, therefore, the umbrella-shaped ink advances to the part outside of the board edge to form the repeated spraying of the edge of the board, when the ink advances to the inside of the board from the outside of the board edge, the umbrella-shaped ink can be partially rolled into the other side of the circuit board, and when the second side spraying is carried out, the second side spraying is equivalent to the secondary spraying of the edge, the excessive spraying of the ink on the board edge is easy to generate, thereby forming the problem of oil accumulation, and influencing the subsequent processing of the circuit board.

In the embodiment, the nail plate (70) is designed to serve as an auxiliary supporting structure of the circuit board (80) to be sprayed, the supporting hole (810) is utilized to correspond to the nail head (710), the circuit board (80) to be sprayed is placed on the nail plate (70), the width direction of the nail plate (70) is preset to a certain extent, when spraying is carried out, when the umbrella-shaped ink spraying device sprays the edge of the circuit board, the nail plate (70) is used for further ink bearing, the phenomenon that the umbrella-shaped ink is rolled into the edge of the other side of the circuit board in the back spraying process is avoided, and the problem that oil is collected at the edge of the board can be effectively avoided.

And the design of pin fin (710) and support hole (810) that corresponds need avoid the circuit board active area (design in the inactive area) to need do comparatively even distribution (generally design at least circuit board four angles and respectively set up a support hole, the center sets up a support hole at least) according to the circuit board size, ensure to effectively support the circuit board, the circuit board scheduling problem of buckling can not appear.

The width direction of the nail plate (70) is also required to be provided with a clamp avoiding groove (720), and an effective clamping position is provided for a clamp of the turning plate (turnover) in the machining process.

Referring to fig. 8c, fig. 8c is a schematic diagram of a turning plate for processing a thick copper circuit board sprayed with a solder mask layer according to the present embodiment; as shown in the figure, a circuit board (80) to be sprayed is placed on a nail plate (70) in an aligned mode to form an integral structure of the nail plate (70) + the circuit board (80) to be sprayed, the integral structure is placed on a conveying chain (910) in a processing mode, generally, the conveying chain only supports (or clamps) the board edge, after a first surface is sprayed, the integral structure advances to the position of a turning plate chuck (940), after the equipment senses that the turning plate chuck (940) penetrates through a clamp position avoiding groove (720) to clamp the board edge of the circuit board, a turning plate connecting rod (930) is driven to rotate by a turning plate shaft (920), at the moment, the nail plate (70) still transmits forwards on the conveying chain (910), when the circuit board is turned to the other surface, the nail plate (70) basically advances to the position corresponding to the circuit board, and under the alignment of an alignment lens (950), the circuit board is placed on the nail plate (70) again, and solder resist ink spraying of a second surface is further completed; this structure has realized nailing board (70) and the split type course of working of treating spraying circuit board (80), and the dismantlement and the reinstallation of nailing board (70) accessible pin fin (710), realizes using repeatedly, can play effectual "expand limit" and supporting role for treating spraying circuit board (80), prevents that the board edge from gathering oily problem and producing.

Referring to fig. 9, fig. 9 is a schematic structural diagram of a thick copper circuit board solder mask layer according to a method for manufacturing a thick copper circuit board solder mask layer of the present invention; in the embodiment, after the following final manufacturing steps, a thick copper circuit board solder mask layer (10) structure is formed:

s40: and carrying out integral solder mask pattern processing on the circuit board to be subjected to solder mask processing to form the thick copper circuit board solder mask layer structure (10).

It should be noted that the method for manufacturing a solder mask layer of a thick copper circuit board provided in this embodiment is generally used for manufacturing a thick copper circuit board of a simple conductivity type, and can also be used for manufacturing a circuit board having performance requirements such as inductance value, impedance value, etc., but the performance requirements such as inductance value, impedance value, etc. of the circuit board need to be subjected to advanced pattern design in advance with respect to the matching of the circuit processing, and the circuit processing mode needs to be controlled during the processing process to obtain a circuit board with good characteristics.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims (10)

1. A method for manufacturing a solder mask layer of a thick copper circuit board is characterized by comprising the following steps:

s10: providing a thick copper clad laminate, wherein the thick copper clad laminate comprises a circuit copper layer and a substrate layer, a first etching circuit is firstly manufactured on the thick copper clad laminate, then a second etching circuit is manufactured, and the first etching circuit and the second etching circuit form an etching circuit integrally;

s20: silk-screening the first solder mask layer on the etching circuit by using a screen printing plate, and performing precuring → exposure → development → baking and curing → polishing processing to form a circuit board to be sprayed;

s30: spraying a second solder mask layer on the circuit board to be sprayed, and then spraying a third solder mask layer to form a circuit board to be subjected to solder mask processing;

s40: and carrying out integral resistance welding pattern processing on the circuit board to be subjected to resistance welding processing to form the thick copper circuit board resistance welding layer.

2. The method for making the solder mask of the thick copper circuit board as claimed in claim 1, wherein the thickness of the circuit copper layer is more than or equal to 105 μm.

3. A method for making a solder mask layer of a thick copper circuit board according to claim 1, wherein the method for making the first etching circuit in advance comprises:

performing single-side pre-reduction adjustment on the circuit pattern in the set design data, and performing first pattern transfer processing to form the first etching circuit;

the first pattern transfer processing process is to paste a dry film on the circuit copper layer, and then carry out exposure → development → etching → film removal;

the etching thickness of the first etching line is 1/2 to 1/3 of the copper layer of the line.

4. A method for making a solder mask layer for a thick copper circuit board according to claim 3, wherein said method for making a second etching line further comprises:

performing a second pattern transfer process according to the circuit pattern in the predetermined design data to form the second etching circuit; integrally forming the etched circuit after processing;

the second pattern transfer processing process is to coat a wet film layer on the circuit board of the first etching circuit, and then carry out exposure → development → etching → film removal;

the etching thickness of the second etching line is the thickness of the line copper layer after the first etching line is etched.

5. A method for making a solder mask layer of a thick copper circuit board according to claim 1, wherein the method for making the first etching circuit in advance comprises:

selecting the thick copper-clad plate which is larger than the circuit copper layer specified by the established design data by a certain thickness in advance, and manufacturing a circuit guide groove on the circuit copper layer;

the circuit guiding groove is formed by arranging a fine circuit pattern with the width smaller than the set line width to be etched at the middle position of the line width of the surface of each circuit pattern in the set design data, and then performing whole plate dry film attaching → exposure → development → etching → film removing.

6. The method for fabricating a solder mask layer for a thick copper circuit board according to claim 5, wherein the method for fabricating the second etched circuit further comprises:

performing a second pattern transfer process according to the width of the circuit pattern in the predetermined design data to form a second etched circuit; and integrally forming the etched line after processing.

7. The method for manufacturing a thick copper circuit board solder mask according to claim 1, wherein said screen is a dot-blocking screen, and a side area of said etched circuit corresponding to said dot-blocking screen is a blank screen area.

8. The method for manufacturing a thick copper circuit board solder mask according to claim 1, wherein the pre-curing → exposing → developing → baking curing → grinding process is as follows:

the curing parameters of the pre-curing are multiplied by 75 ℃ for 30min to 45min;

the exposure is carried out by pre-enlarging the second etching line by 10-50 mu m according to the pattern of the second etching line;

the baking and curing step is to completely cure the ink by using the parameters of 150 ℃ multiplied by 60min to 90 min;

and the polishing is performed by using a nylon polishing brush or a non-woven fabric polishing brush.

9. A method for making a thick copper circuit board solder mask according to claim 1, characterized in that said second solder mask is pre-sprayed by a low pressure spraying method, and the thickness of said second solder mask formed by said pre-spraying is 5.0 μm to 10.0 μm; and the second solder mask is sprayed by adopting a low-pressure spraying method, wherein the thickness of the third solder mask formed by the main spraying is 15-40 mu m.

10. The method for manufacturing the solder mask of the thick copper circuit board according to claim 9, wherein the low-pressure spraying adopts a nail plate support fixed spraying, and the nail plate support fixed spraying is as follows:

s310: manufacturing a nail plate supporting hole in the invalid area of the circuit board to be sprayed;

s320: manufacturing a nail plate, wherein the nail plate is manufactured by arranging nail heads on a light plate, the nail heads are distributed corresponding to the support holes, the maximum diameter of a cylinder of the nail heads is larger than that of the support holes, and two sides of the nail plate along the advancing direction of the low-pressure spraying are provided with clamp avoiding grooves;

s330: and placing the circuit board to be sprayed on the nail plate, setting the transportation width of low-pressure spraying equipment to be the width of the nail plate, and performing low-pressure spraying.

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