CN114585154A

CN114585154A - Circuit board manufacturing structure and circuit board manufacturing method

Info

Publication number: CN114585154A
Application number: CN202011401033.9A
Authority: CN
Inventors: 王昌水; 段龙辉; 于民生
Original assignee: Shanghai Meadville Science and Technology Co Ltd
Current assignee: Shanghai Meadville Science and Technology Co Ltd
Priority date: 2020-12-02
Filing date: 2020-12-02
Publication date: 2022-06-03

Abstract

The invention provides a circuit board manufacturing structure and a circuit board manufacturing method, wherein the manufacturing method comprises the following steps: providing a substrate with a defined blind groove area, manufacturing a PI film bottom protective layer in the blind groove area based on laser cutting, laminating the substrate with a prepreg and a copper foil, defining a cover uncovering area based on the laser cutting, attaching a blue film to the cover uncovering area, and removing the cover uncovering blue film to obtain the blind groove. The invention provides a novel method for manufacturing a blind slot in a PCB (printed circuit board). based on the technical scheme of the invention, a PI (polyimide) film is used as a bottom protective layer of a circuit pattern part, then a semi-cured sheet and a metal foil are laminated, and the residual adhesive in the manufacture of the blind slot can be effectively reduced by a blue film uncovering mode, so that the method is suitable for manufacturing the PCB with smaller size and higher requirement on the manufacture precision of the blind slot.

Description

Circuit board manufacturing structure and circuit board manufacturing method

Technical Field

The invention belongs to the technical field of PCB (printed circuit board) manufacturing, and particularly relates to a circuit board manufacturing structure and a manufacturing method thereof.

Background

In order to meet the demand of thinner electronic products/parts, the PCB blind slot technology is developed. The traditional electronic product/part is to assemble electronic components on the surface of the PCB, the thickness of the finished product is determined by the superposition of the thickness of the PCB and the thickness of the electronic components, and the blind slot PCB is to embed the electronic components in the PCB, so that the total thickness of the finished product is effectively reduced.

However, there are a number of problems with the existing blind slot fabrication. For example, most of the existing blind slot PCB processing methods use special low-flow prepreg, and laminate the prepreg after windowing to form a cavity, and then remove the redundant part on the blind slot (referred to as uncovering in the industry) by a mechanical depth control milling or laser processing method after the PCB is finished, so as to expose the blind slot. The processing method is feasible for products with larger size and low precision requirement, but when the size of the PCB is small and the precision requirement of the blind slot is high, the processing method has inherent defects: the low-flow prepreg has poor flow stability, and the problem of local excessive flow or insufficient flow is easy to occur; when the cover is uncovered, manual operation is needed, and due to the small size of the PCB, thousands of blind grooves are formed in one processing plate, so that the efficiency is extremely low.

Therefore, how to provide a new circuit board manufacturing structure and a manufacturing method thereof are necessary to solve the above problems.

Disclosure of Invention

In view of the above disadvantages of the prior art, an object of the present invention is to provide a circuit board manufacturing structure and a manufacturing method thereof, which are used to solve the problems of low blind via manufacturing efficiency and poor blind via accuracy in the prior art.

In order to achieve the above and other related objects, the present invention provides a method for manufacturing a circuit board, including the steps of:

providing a substrate, wherein a blind groove area is defined on a first surface of the substrate, and a circuit pattern part is prepared in the blind groove area;

forming a protective film on the first face to cover at least the blind groove region, the protective film including a PI film;

cutting the protective film by adopting a laser cutting process to obtain a bottom protective layer positioned in the blind groove area;

laminating the substrate, a prepreg module and a metal foil module, wherein the prepreg module at least comprises a first prepreg and a second prepreg, the metal foil module at least comprises a first metal foil and a second metal foil, the second prepreg, the substrate, the first prepreg and the first metal foil are sequentially stacked from bottom to top, and the first prepreg covers the bottom protective layer;

cutting from one side of the first metal foil along the edge of the blind slot area by adopting a laser cutting process so as to define a cover uncovering area in the first metal foil and the first curing sheet;

forming a cover uncovering film on the surface of the cover uncovering area; and

and removing the cover removing film and taking away the material layer in the cover removing area and the bottom protective layer to obtain a blind groove exposing the circuit pattern part.

Optionally, one side of the PI film is coated with a glue layer, and the side of the PI film having the glue layer is in contact with the first side of the substrate, wherein the PI film and the substrate have a first bonding force therebetween, and the first bonding force is between 5g/25mm and 40g/25 mm.

Optionally, the cover removing film is a blue film, a second bonding force is formed between the cover removing film and the surface of the cover removing area, and the cover removing film is removed in a hand tearing manner, wherein the second bonding force is greater than the first bonding force in the process of removing the cover removing film.

Optionally, the method further comprises a step of pretreating the blue film before removing the blue film, wherein the pretreatment process comprises: and heating the uncovering film, wherein the heating temperature of the heating treatment is between 60 and 120 ℃, and the heat preservation time at the heating temperature is between 10 and 60 min.

Optionally, a manner of forming the bottom protective layer includes: covering the whole protective film on the surface of the substrate, cutting the protective film on the substrate, and removing the redundant protective film after cutting in a manner of tearing by hand to obtain the bottom protective layer, wherein UV laser cutting is adopted in the process of cutting the protective film, the cutting speed of the UV laser cutting is between 200 and 400mm/s, and the energy is between 3 and 6 watts; or a CO2 laser cutting process is adopted in the process of cutting the protective film, the energy of CO2 laser cutting is between 0.5 and 2mj, the size of a mask is between 0.8 and 2.0mm, the pulse width is between 3 and 10us, and the number of hairs is between 2 and 7.

Optionally, the thickness of the first semi-cured sheet is set based on the thickness of the PI film and the thickness of the circuit pattern part, the thickness of the first semi-cured sheet is greater than or equal to the thickness of the circuit pattern part (% 1-pattern area outside the blind grooves) + the thickness of the PI film (% 1-pattern area (%) + the thickness of the glass fiber cloth + a compensation thickness in the first semi-cured sheet, wherein the compensation thickness is between 4 and 8 μm.

Optionally, the uncovering area is defined using a CO2 laser cutting process, wherein a cut path is formed covering an interface between the bottom protective layer and the first semi-cured sheet.

Optionally, during the CO2 laser cutting process defined by the uncovering area, the adjacent cutting spots have a cutting distance with the diameter between 1/4-1/2 of the cutting spot diameter; the energy of CO2 laser cutting is between 2-10mj, the aperture size is between 0.8-2.0mm, the pulse width is between 3-8us, and the number of hairs is between 1-3.

Optionally, a bottom blocking portion is further formed on the first surface of the substrate, and an edge of the bottom protection layer is correspondingly located on the bottom blocking portion.

Optionally, a distance between an edge of the bottom protective layer and an edge of the bottom barrier portion on a side away from the pattern line portion is between 50 and 500 μm.

Optionally, a process of performing a surface treatment on the bottom barrier portion is further included before forming the protective film, the surface treatment process includes at least one of a browning treatment and a super-roughening treatment, wherein when the thickness of the bottom barrier portion is less than 15 μm, the surface treatment process is selected to be the super-roughening treatment.

Optionally, the method for manufacturing a circuit board further includes a step of preparing an auxiliary cover-uncovering portion in the blind groove region, where the auxiliary cover-uncovering portion includes a main body portion formed on the first surface of the substrate and a groove formed in the main body portion.

Optionally, the cross-sectional shape of the grooves comprises at least one of circular, rectangular, triangular and polygonal shapes, the width of the grooves is between 0.15 and 1mm, and when a plurality of the grooves are formed, the distance between the grooves is between 0.2 and 5 mm; the distance between the edge of the groove and the edge of the cutting path of the CO2 laser cut performed when defining the uncovering area is larger than 50 μm.

The invention also provides a circuit board structure, which is preferably prepared by the circuit board manufacturing method of the invention, and of course, can also be prepared by other methods, and the circuit board structure comprises:

the circuit board comprises a substrate, wherein a blind groove area is defined on a first surface of the substrate and is provided with a circuit pattern part;

a bottom protective layer covering the blind trench region, the bottom protective layer including a PI film;

the prepreg assembly at least comprises a first prepreg and a second prepreg, the metal foil assembly at least comprises a first metal foil and a second metal foil, and the second metal foil, the second prepreg, the substrate, the first prepreg and the first metal foil are sequentially stacked from bottom to top;

the first metal foil and the first curing sheet define a cover-uncovering area, and the cover-uncovering area corresponds to the bottom protective layer so as to take away the bottom protective layer based on the cover-uncovering area material layer to form a blind groove for exposing the circuit pattern part.

Optionally, the thickness of the first semi-cured sheet is set based on the thickness of the PI film and the thickness of the circuit pattern part, wherein the thickness of the first semi-cured sheet is greater than or equal to the thickness of the circuit pattern part (% of pattern area outside the blind grooves) + the thickness of the PI film (% of pattern area outside the blind grooves) + the thickness of the glass fiber cloth in the first semi-cured sheet + a compensation thickness, and the compensation thickness is between 4 and 8 μm.

Optionally, the first surface of the substrate is further formed with a bottom blocking portion, and an edge of the bottom protection layer is correspondingly located on the bottom blocking portion, wherein a distance between the edge of the bottom protection layer and an edge of the bottom blocking portion on a side away from the pattern circuit portion is between 50 and 500 μm; the thickness of the bottom obstruction is proportional to the depth of the blind groove.

Optionally, the circuit board structure further includes an auxiliary cover-uncovering portion located in the blind groove region, and the auxiliary cover-uncovering portion includes a main body portion formed on the first surface of the substrate and a groove formed in the main body portion.

Based on the technical scheme of the invention, the PI film is used as a bottom protective layer of the circuit pattern part, the semi-cured sheet and the metal foil are laminated, and the blue film is used for uncovering, so that the residual glue in the manufacture of the blind groove can be effectively reduced, and the manufacturing structure and the manufacturing method of the circuit board are suitable for the manufacture of the circuit board with smaller PCB size and higher requirement on the manufacture precision of the blind groove.

Drawings

Fig. 1 shows a process flow diagram of the circuit board manufacturing method of the present invention.

Fig. 2 is a schematic structural diagram of a substrate provided in the manufacturing of a circuit board according to an example of the present invention.

Fig. 3 is a schematic diagram illustrating the formation of a protective film in the fabrication of a circuit board according to an embodiment of the present invention.

Fig. 4 is a schematic diagram illustrating laser cutting of the protective film in the manufacturing of the circuit board according to an example of the present invention.

Fig. 5 is a schematic diagram illustrating the formation of a bottom passivation layer in the fabrication of a circuit board according to an embodiment of the invention.

Fig. 6 is a schematic diagram illustrating the formation of a prepreg module and a metal foil module in the fabrication of a circuit board according to an example of the present invention.

Fig. 7 is a schematic diagram illustrating laser cutting to define a uncovering area in the circuit board manufacturing process according to an exemplary embodiment of the present invention.

Fig. 8 is a schematic diagram showing the cutting process without the bottom blocking portion in the circuit board manufacturing process according to an example of the present invention.

Fig. 9 is a schematic diagram illustrating the formation of a cover-removed film in the fabrication of a circuit board according to an embodiment of the present invention.

Fig. 10 is a schematic diagram illustrating formation of blind via after uncovering in the circuit board manufacturing process according to an exemplary embodiment of the present invention.

Fig. 11 is a diagram showing a circuit connection structure formed around the blind slot region in the circuit board manufacturing process of the present invention.

Fig. 12(a) and 12(b) show auxiliary lid release parts according to different embodiments of the present invention.

Description of the element reference numerals

100 substrate

100a blind groove area

101 line pattern part

102 protective film

103 bottom protective layer

104 first semi-cured sheet

105 second prepreg

106 first metal foil

107 second metal foil

108 uncovering area

109 uncovering film

110 bottom barrier

111 blind groove

112 uncovering auxiliary part

113 main body part

114 groove

S1-S7

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

As in the detailed description of the embodiments of the present invention, the cross-sectional views illustrating the device structures are not partially enlarged in general scale for convenience of illustration, and the schematic views are only examples, which should not limit the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in the actual fabrication.

For convenience in description, spatial relational terms such as "below," "beneath," "below," "under," "over," "upper," and the like may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that these terms of spatial relationship are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the figures. Further, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. In addition, "between … …" as used herein includes both endpoints.

In the context of this application, a structure described as having a first feature "on" a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed in between the first and second features, such that the first and second features may not be in direct contact.

It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the drawings only show the components related to the present invention rather than being drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of each component in actual implementation may be changed freely, and the layout of the components may be more complicated.

As shown in fig. 1, the present invention provides a method for manufacturing a circuit board, including the steps of:

s1, providing a substrate, wherein a blind groove area is defined on the first surface of the substrate, and the blind groove area is provided with a circuit pattern part;

s2, forming a protection film on the first surface to cover at least the blind groove region, the protection film including a PI film;

s3, cutting the protective film by adopting a laser cutting process to obtain a bottom protective layer positioned in the blind groove area;

s4, laminating the substrate, a prepreg module and a metal foil module, wherein the prepreg module at least comprises a first prepreg and a second prepreg, the metal foil module at least comprises a first metal foil and a second metal foil, the second prepreg, the substrate, the first prepreg and the first metal foil are sequentially stacked from bottom to top, and the first prepreg covers the bottom protective layer;

s5, cutting the first metal foil along the edge of the blind groove area from one side of the first metal foil by adopting a laser cutting process so as to define a cover-uncovering area in the first metal foil and the first solidified sheet;

s6, forming a cover-removing film on the surface of the cover-removing area; and

and S7, removing the cover removing film and taking away the material layer in the cover removing area and the bottom protective layer to obtain a blind groove exposing the circuit pattern part.

The method for manufacturing a circuit board according to the present invention will be described in detail with reference to the accompanying drawings, wherein it should be noted that the above sequence does not strictly represent the preparation sequence of the method for manufacturing a circuit board protected by the present invention, and those skilled in the art can change the steps according to the routine choice in the art, and fig. 1 only shows the preparation steps of the method for manufacturing a circuit board in one example.

First, as shown in S1 of fig. 1 and fig. 2, a substrate 100 is provided, a blind groove region 100a is defined on a first surface of the substrate 100, and the blind groove region 100a is prepared with a circuit pattern portion 101.

Specifically, the substrate 100 may be a core board commonly used in the field of PCB circuit board manufacturing, or may be a multilayer board. The first side may be defined according to practical situations, and as shown in fig. 2, may be an upper surface of the substrate 100. In addition, the structure, distribution, thickness, etc. of the circuit pattern part (e.g. copper) 101 can be set according to actual requirements. In addition, the circuit pattern part 101 is formed on the surface of the substrate 100 corresponding to the blind via region 100a, and may be formed by a conventional process. Of course, the surface area of the substrate 100 outside the blind trench area 100a may also be prepared with other structures, such as connecting lines, etc., as shown in fig. 11, an existing interlayer connection conducting structure is formed around the blind trench, which may be prepared by, after lamination, first drilling with CO2 laser, then electroplating, and finally performing pattern etching, and may be prepared by an existing process flow.

Next, as shown in S2 in fig. 1 and fig. 3, a protection film 102 is formed on the first surface to cover at least the blind trench area 100a, and the protection film 102 includes a PI film.

Specifically, the protective film 102 is attached to the surface of the substrate 100, and covers the circuit pattern portion 101 provided in the blind groove area 100a, but may cover an area other than the blind groove area 100 a. In one example, the protection film 102 is only a PI film, and in other examples, other material layers may be disposed on the PI film to form the protection film 102. The PI film is selected as the protective film 102, so that the problems that bubbles are easy to exist and viscosity is difficult to control effectively in the existing other protective films, the removing process is difficult to tear off, and residual glue is left can be solved.

As an example, one side of the PI film is coated with a glue layer (not shown), and the side having the glue layer is in contact with the first side of the substrate 100. The bonding force between the PI film and the substrate 100 can be regulated and controlled through the adhesive layer, wherein the bonding force of the adhesive layer is related to the adhesive components and the curing degree of the adhesive, and the bonding force can be controlled through the curing degree. In one example, the PI film has a first binding force with the substrate 100, e.g., the first binding force is between 5g/25mm and 40g/25mm based on the bondline modulation, e.g., 10g/25mm, 12g/25mm, 15g/25mm, 20g/25mm, 30g/25 mm. Selecting a PI film with the binding force between 5g/25mm and 40g/25mm, wherein the glue-containing surface of the PI film is in contact with the bottom of the blind groove, so that the bottom of the blind groove can be protected, the resin of the prepreg is prevented from flowing into the blind groove in the laminating process, and meanwhile, no glue residual plate surface on the PI film exists after uncovering; and the cover is easy to remove due to the small binding force.

Next, as shown in S3 in fig. 1 and fig. 4-5, the protective film 102 is divided by a laser cutting process to obtain the bottom protective layer 103 located in the blind trench region 100 a.

As an example, the manner of forming the bottom protective layer 103 includes: the entire protective film 102 is covered on the surface of the substrate 100, the protective film 102 is divided on the substrate 100, and the redundant protective film 102 after division is removed in a manner of tearing by hand, that is, based on the scheme of the present invention, the entire PI film can be directly attached on the surface of the substrate 100, and PI cutting is performed on the substrate 100 to remain the PI film covering the blind groove area 100a, so as to obtain the bottom protective layer 103. Can not use equipment such as sticking film machine, improve cutting accuracy, improve cutting efficiency. In one example, the cutting adopts the optical alignment point alignment etched out from the blind groove surface, the position precision of the PI film can be controlled to +/-25um very accurately, and the precision is +/-75um at most when the traditional cutting is adopted and then the PI film is attached to the bottom of the blind groove; in addition, the invention has high efficiency, and for the design with small size of the blind slot, one PCB board can have thousands of blind slots, and if the mode of molding firstly and then pasting is adopted, the efficiency is too low.

As an example, the CO2 laser cutting process is used in the process of cutting the protective film 102, so that the residue of particles causing the PI film to be cut in the cutting process can be reduced. The traditional blind groove forming process usually adopts gong forming, the position precision of the gong forming cutting is better compared with CO2 laser, the precision of the cutting path and the blind groove position can be controlled to +/-25um, and the precision of the gong forming is poorer, generally +/-50-100 um; in addition, the depth of the blind groove can be thin, which is about 40um minimum, by using the CO2 laser cutting, and the routing is generally at least 100um above due to the problem of depth tolerance. In one example, the energy of the CO2 laser cutting is between 0.5-2mj, for example, 1mj, 1.2mj, 1.5mj, 1.8 mj; the aperture size is between 0.8-2.0mm, and may be, for example, 1mm, 1.2mm, 1.5 mm; the pulse width is between 3-10us, for example, 5us, 6us, 8 us; the number of hairs is between 2 and 7, and may be, for example, 3, 5, 6. In addition, in another preferred example, UV laser cutting is adopted, the cutting speed of the UV laser cutting is between 200 and 400mm/s, can be 250mm/s and 300mm/s, and the energy is between 3 and 6watts, and can be 4watts and 5 watts.

Next, as shown in S4 in fig. 1 and fig. 6, the substrate 100 with the bottom passivation layer 103 formed thereon is laminated with a prepreg assembly and a metal foil (e.g., copper foil) assembly, wherein the prepreg assembly at least includes a first prepreg 104 and a second prepreg 105, the metal foil assembly at least includes a first metal foil 106 and a second metal foil 107, the second prepreg 105, the substrate 100, the first prepreg 104, and the first metal foil 106 are stacked in sequence from bottom to top, and the first prepreg 104 covers the bottom passivation layer 103. Besides, the method can also comprise the conventional steps of drilling, electroplating, patterning, welding resistance and the like, and can also comprise a plurality of lamination processes.

In an example, the second prepreg 105 and the second metal foil 107 are disposed on two opposite surfaces of the substrate 100 corresponding to the first prepreg 104 and the first metal foil 106, respectively, to form a symmetrical structure. Of course, the prepreg assembly may further include other prepregs, and the metal foil assembly may further include other metal foils to form a stacked structure. Preferably, each prepreg is symmetrically distributed about the substrate, and each metal foil is symmetrically distributed about the substrate. In addition, in one example, after lamination, the laser cutting is performed after the laser blind via-copper-pattern etching-solder resist is performed according to the conventional PCB process. The lamination process may be one-time lamination, or may be cutting after a PCB with a higher number of layers is formed by multiple times of lamination, and may specifically be set according to actual requirements.

As an example, the first prepreg thickness is set based on the thickness of the PI film and the thickness of the circuit pattern part 101, wherein the first prepreg thickness is equal to or greater than the circuit pattern part thickness (% pattern area outside the blind via area) + the PI film thickness (% 1-blind via area) + the glass cloth thickness + compensation thickness in the first prepreg, wherein the compensation thickness is between 4 μm and 8 μm, and may be, for example, 5um, 6um, or 7 um. The proportion of the area of the pattern of the area outside the blind groove is the area of the first surface of the substrate outside the blind groove area, and is defined as a non-blind groove area, and other circuit patterns required in the field are also arranged in the non-blind groove area, and the percentage is the percentage of the area of the circuit pattern of the part of the area of the non-blind groove area; in addition, the ratio of the area of the blind groove region is the percentage of the area of the blind groove region to the area of the first surface of the whole substrate. Furthermore, the thickness of the glass fiber cloth in the prepreg is known from the existing prepreg itself. The thickness of the prepreg is beneficial to ensuring that enough resin is filled in the pattern area and a gap caused by the thickness of a PI film, and is beneficial to preventing a lamination cavity from being formed; in addition, the compensation thickness is favorable for ensuring that some resin residues can be left after the gap is filled, on one hand, the filling is favorable for ensuring that the filling is enough, and on the other hand, the product reliability is favorable for being better.

Next, as shown in S5 of fig. 1 and fig. 7-8, a laser cutting process is used to cut along the edge of the blind spot region 100a from one side of the first metal foil 106 so as to define a cover-off region 108 in the first metal foil 106 and the first cured sheet 104.

As an example, in defining the uncovering area, the laser process is selected as a CO2 laser cutting process, wherein a cutting path is formed covering the interface between the bottom protective layer 103 and the first semi-cured sheet 104. The method is beneficial to the removal of the bottom protective layer 103 in the cover removing process and the cover removing process.

As an example, during the CO2 laser cutting process defined by the uncovering area, the adjacent cutting spots have a cutting distance between 1/4-1/2 of the diameter of the cutting spot; for example, 1/3 may be used. Wherein the cutting pitch referred to herein may be the distance between two centers of the circular spots. In one example, the energy of the CO2 laser cut is between 2-10mj, for example, 5mj, 6mj, 8 mj; the mask size is between 0.8mm and 2.0mm, for example, 1mm, 1.2mm, 1.5 mm; the pulse width is between 3-8us, for example, 5us, 6us, 7 us; the number of hairs is between 1-3, which may be 2, for example. So that the cutting path of the CO2 has proper width, and is favorable for ensuring the cutting completion and avoiding the damage of laser energy to the barrier layer in the cutting process.

As an example, the first surface of the substrate 100 is further formed with a bottom blocking portion 110, and an edge of the bottom protection layer 103 is correspondingly located on the bottom blocking portion 110. The bottom blocking portion 110 may be made of the same material as the pattern circuit portion 101 through the same process, and may have a distance from the pattern circuit portion.

As an example, the distance between the edge of the bottom protection layer 103 and the edge of the bottom blocking portion 110 on the side away from the pattern circuit portion 101, for example, the distance w in fig. 7, is set to be between 50 μm and 500 μm, for example, 100 μm, 200 μm, and 300 μm, so as to facilitate CO2 laser cutting and improve the deviation in the laser processing. Additionally, in one example, the thickness of the bottom barrier 110 is positively correlated to the depth of the blind slot. To accommodate CO2 laser cutting. In one example, when the bottom barrier 110 is not present, as shown in FIG. 8, UV laser cutting is preferred to facilitate etch depth control.

As an example, before forming the protective film 102, a surface treatment process of performing a surface treatment on the bottom barrier portion 110 is further included, the surface treatment process includes at least one of a browning process and a super-roughening process, wherein when the thickness of the bottom barrier portion 110 is less than 15 μm, for example, 8 μm, 10 μm, and 12 μm, the surface treatment process is preferably the super-roughening process. Is beneficial to preventing the laser etching process from breakdown.

Next, as shown in S6 in fig. 1 and fig. 9, a cover-removing film 109 is formed on the surface of the cover-removing region 108;

finally, as shown in S3 of fig. 1 and fig. 10-12, the cover-removing film 109 is removed and the material layer of the cover-removing region 108 and the bottom passivation layer 103 are removed, so as to obtain the blind via 111 exposing the circuit pattern portion 101. In an example, the surfaces corresponding to the blind groove surface and the blind groove surface may be processed and manufactured at the same time, and in addition, the blind groove may be manufactured on one surface or on two opposite surfaces, and the design is performed according to the actual situation, see fig. 11, which is shown as a schematic diagram of a single-sided blind groove.

As an example, the cover-removing film 109 is selected to be a blue film, a second bonding force is provided between the cover-removing film 109 and the surface of the cover-removing region 108, and the cover-removing film 109 is removed by hand tearing, wherein the second bonding force is greater than the first bonding force during the process of removing the cover-removing film.

As an example, before removing the blue film, a process of pretreating the blue film is further included, and the pretreatment process includes: the release film 109 is heat treated, for example, by heating the entire structure together, in one example, at a temperature between 60 ℃ and 120 ℃, for example, 80 ℃, 90 ℃, 100 ℃; the holding time at the heating temperature is 10-60min, for example, 20min, 30min, 40 min. The cover opening process in the mode of the invention is completed by being matched with the first binding force in order to be beneficial to controlling the size of the second binding force, so that no residual glue is left. The method is beneficial to the preparation of small-size PCB and blind slot with high precision requirement.

In addition, in an example, the first surface of the substrate 100 may define a plurality of blind trench regions 100a, so that the process of the present invention can simultaneously uncover a plurality of blind trench regions, thereby improving efficiency.

As an example, the manufacturing method of the circuit board further includes a step of preparing an auxiliary cover-uncovering part 112 in the blind slot region 100a, as shown in the auxiliary cover-uncovering part in the circuit of fig. 12 (a). The uncovering aid 112 comprises a main body 113 formed on the first side of the substrate 100 and a recess 114 in the main body 113. The material of the auxiliary cover part 112 may be metal, for example, the auxiliary cover part 112 may be formed by the same process and the same material as the circuit pattern part 101 and the bottom barrier part 110 (when present), so as to obtain an initial structure, the groove 114 is formed therein, and the rest is formed as a protrusion.

In addition, in an example, the bottom barrier 110 may serve as the auxiliary uncovering part at the same time, that is, the groove 114 is prepared in the bottom barrier, so that the structure serves as the uncovering auxiliary part 112 including the groove and the main body part at the same time, as shown in fig. 12(b), in an example, the bottom barrier 110 is a ring-shaped structure, and the grooves 114 are uniformly spaced in the ring-shaped bottom barrier. The existence of the groove 114 can leave a gap when the protective film is formed, thereby facilitating the easy separation of the protective film and the bottom of the blind groove.

As an example, the cross-sectional shape of the groove 114 includes at least one of a circle, a rectangle, a triangle, and a polygon, that is, one of the shapes may be used, and a combination of two or more of the shapes may be used. In addition, the width of the groove 114 is between 0.15-1mm, for example, 0.2mm, 0.5mm, 0.8mm, wherein the width refers to the maximum dimension of the edge line, diameter for a circle, diagonal length for a square, and so on. In addition, when a plurality of the grooves 114 are formed, the distance between the grooves 114 is between 0.2mm and 5mm, for example, 0.3mm and 0.4mm, wherein the distance refers to the nearest adjacent edge of the adjacent grooves, such as the distance d1 between the adjacent circular grooves in fig. 11.

In other examples, the distance between the edge of the groove 114 and the edge of the CO2 laser cut performed to define the lift-off region is greater than 50 μm, and may be, for example, 60 μm, 80 μm, 120 μm. Where distance refers to the closest distance of the groove edge to the laser cutting path, such as distance d2 resulting from the circular groove in fig. 11.

In addition, as shown in fig. 10 to 11 and referring to fig. 1 to 9, the present invention also provides a circuit board manufacturing structure, which is preferably manufactured by the circuit board manufacturing method of the present invention, but may be manufactured by other methods. In this embodiment, each structural feature and description of the circuit board manufacturing structure may refer to the description in the circuit board manufacturing method, and are not described herein again. Wherein, circuit board preparation structure includes:

a substrate 100, a blind groove area 100a is defined on a first surface of the substrate, and a circuit pattern part 101 is prepared in the blind groove area;

a bottom protective layer 103 covering the blind trench region 100a, the bottom protective layer 103 including a PI film;

the prepreg assembly at least comprises a first prepreg 104 and a second prepreg 105, the metal foil assembly at least comprises a first metal foil 106 and a second metal foil 107, and the second metal foil 107, the second prepreg 105, the substrate 100, the first prepreg 104 and the first metal foil 106 are sequentially stacked from bottom to top;

the first metal foil 106 and the first curing sheet 104 define a cover-off region 108, and the cover-off region 108 corresponds to the bottom passivation layer 103, so that the bottom passivation layer 103 is taken away by the material layer based on the cover-off region 108 to form a blind trench 111 exposing the circuit pattern 101.

As an example, the thickness of the first semi-cured sheet 104 is set based on the thickness of the PI film and the thickness of the circuit pattern portion 101, wherein the thickness of the first semi-cured sheet 104 is equal to the thickness of the circuit pattern portion 101 (% by area of the pattern in the region other than the blind via) + the thickness of the PI film (% by area of the blind via) + the thickness of the glass fiber cloth + the compensation thickness in the first semi-cured sheet 104, and wherein the compensation thickness is between 4 μm and 8 μm.

As an example, the first surface of the substrate 100 is further formed with a bottom blocking portion 110, an edge of the bottom protection layer 103 is correspondingly located on the bottom blocking portion 110, wherein a distance w between the edge of the bottom protection layer 103 and an edge of the bottom blocking portion 110 on a side away from the pattern circuit portion 101 is greater than 100 μm; the thickness of the bottom barrier 101 is proportional to the depth of the blind groove 111.

As an example, the circuit board manufacturing structure further includes an auxiliary cover-uncovering portion 112 located in the blind slot region 100a, and the auxiliary cover-uncovering portion includes a main body portion 113 formed on the first surface of the substrate and a groove 114 formed in the main body portion.

In summary, the present invention provides a novel method for manufacturing a blind via in a PCB, and based on the technical scheme of the present invention, a PI film is used as a bottom protection layer of a circuit pattern portion, and then a semi-cured sheet and a metal foil are laminated, and a blue film is used to uncover the blind via, so that the residual glue in the blind via manufacturing can be effectively reduced, and the present invention is suitable for manufacturing a PCB with a small size and a high requirement for the blind via manufacturing accuracy. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which may be made by those skilled in the art without departing from the spirit and scope of the present invention as defined in the appended claims.

Claims

1. A manufacturing method of a circuit board is characterized by comprising the following steps:

cutting from one side of the first metal foil along the edge of the blind groove area by adopting a laser cutting process so as to define a cover uncovering area in the first metal foil and the first solidified sheet;

2. The method of claim 1, wherein a side of the PI film is coated with a glue layer, and a side of the PI film having the glue layer contacts the first side of the substrate, wherein a first bonding force is between 5g/25mm and 40g/25mm between the PI film and the substrate.

3. The method for manufacturing a circuit board according to claim 2, wherein the cover-removing film is a blue film, a second bonding force is provided between the cover-removing film and the surface of the cover-removing region, and the cover-removing film is removed by hand-tearing, wherein the second bonding force is greater than the first bonding force during the removal of the cover-removing film.

4. The method for manufacturing the circuit board according to claim 3, further comprising a step of pretreating the blue film before removing the blue film, wherein the pretreatment process comprises: and heating the uncovering film at 60-120 ℃ for 10-60 min.

5. The method for manufacturing a circuit board according to claim 1, wherein the forming of the bottom protective layer comprises: covering the whole protective film on the surface of the substrate, dividing the protective film on the substrate, and removing redundant divided protective film in a hand tearing manner to obtain the bottom protective layer, wherein UV laser cutting is adopted in the process of dividing the protective film, the cutting speed of the UV laser cutting is between 200 and 400mm/s, and the energy is between 3 and 6 watts; or a CO2 laser cutting process is adopted in the process of cutting the protective film, the energy of CO2 laser cutting is between 0.5 and 2mj, the size of a mask is between 0.8 and 2.0mm, the pulse width is between 3 and 10us, and the number of hairs is between 2 and 7.

6. The method for manufacturing a circuit board according to claim 1, wherein the thickness of the first prepreg is set based on the thickness of the PI film and the thickness of the circuit pattern portion, and the thickness of the first prepreg is greater than or equal to the thickness of the circuit pattern portion (1-the ratio of the pattern area of the region other than the blind groove region) + the thickness of the PI film (1-the ratio of the area of the blind groove region) + the thickness of the glass fiber cloth in the first prepreg + a compensation thickness, wherein the compensation thickness is between 4 and 8 μm.

7. The method of claim 1, wherein the uncovering region is defined by a CO2 laser cutting process, wherein a cutting path is formed to cover an interface between the bottom protection layer and the first semi-cured sheet.

8. The method for manufacturing the circuit board according to claim 7, wherein in the CO2 laser cutting process defined by the uncovering area, a cutting distance exists between adjacent cutting spots, and the cutting distance is between 1/4-1/2 of the diameter of the cutting spot; the energy of CO2 laser cutting is between 2-10mj, the aperture size is between 0.8-2.0mm, the pulse width is between 3-8us, and the number of hairs is between 1-3.

9. The method for manufacturing a circuit board according to claim 1, wherein a bottom blocking portion is further formed on the first surface of the substrate, an edge of the bottom protective layer is correspondingly located on the bottom blocking portion, and a distance between the edge of the bottom protective layer and an edge of the bottom blocking portion on a side away from the pattern circuit portion is between 50 μm and 500 μm.

10. The method of manufacturing a wiring board according to claim 9, further comprising a surface treatment process of performing a surface treatment on the bottom barrier portion before forming the protective film, wherein the surface treatment process comprises at least one of a browning treatment and an ultra-roughening treatment, and wherein the surface treatment process is selected to be the ultra-roughening treatment when the thickness of the bottom barrier portion is less than 15 μm.

11. A method for manufacturing a wiring board according to any one of claims 1 to 10, further comprising a step of preparing an auxiliary lid-lifting portion in the blind groove region, the auxiliary lid-lifting portion including a main body portion formed on the first surface of the substrate and a groove formed in the main body portion.

12. The method for manufacturing a circuit board according to claim 11, wherein the cross-sectional shape of the groove includes at least one of a circle, a rectangle, a triangle, and a polygon, the width of the groove is between 0.15 mm and 1mm, and when a plurality of grooves are formed, the distance between the grooves is between 0.2mm and 5 mm; the distance between the edge of the groove and the edge of the cutting path of the CO2 laser cutting performed when defining the uncovering area is larger than 50 μm.

13. The utility model provides a circuit board preparation structure which characterized in that, circuit board preparation structure includes:

a bottom protection layer covering the blind trench region, the bottom protection layer including a PI film;

14. The wiring board production structure according to claim 13, wherein the first prepreg thickness is set based on the thickness of the PI film and the thickness of the wiring pattern portion, and the first prepreg thickness is greater than or equal to the wiring pattern portion thickness (% of pattern area in the region other than the blind via) (1%) + the PI film thickness (% of pattern area in the blind via (1%) + the glass fiber cloth thickness in the first prepreg + a compensation thickness, wherein the compensation thickness is between 4 and 8 μm.

15. The circuit board manufacturing structure according to claim 13, wherein a bottom blocking portion is further formed on the first surface of the substrate, an edge of the bottom protective layer is correspondingly located on the bottom blocking portion, and a distance between the edge of the bottom protective layer and an edge of the bottom blocking portion on a side away from the pattern circuit portion is 50-500 μm.

16. The circuit board manufacturing structure according to any one of claims 13 to 15, further comprising an auxiliary cover-uncovering portion located in the blind groove region, wherein the auxiliary cover-uncovering portion comprises a main body portion formed on the first surface of the substrate and a groove formed in the main body portion.