CN117395895A

CN117395895A - PCB manufacturing method and PCB with high thickness-to-diameter ratio

Info

Publication number: CN117395895A
Application number: CN202311323653.9A
Authority: CN
Inventors: 邹佳祁; 唐海波; 杨云
Original assignee: Shengyi Electronics Co Ltd
Current assignee: Shengyi Electronics Co Ltd
Priority date: 2023-10-12
Filing date: 2023-10-12
Publication date: 2024-01-12

Abstract

The application discloses a high thickness-to-diameter ratio PCB manufacturing method and a PCB, wherein the high thickness-to-diameter ratio PCB manufacturing method comprises the following steps: providing a copper-clad plate, and attaching a PTFE film to the copper-clad surface of the copper-clad plate, wherein the copper-clad plate is provided with a first hole to be electroplated and a first through hole, and the first through hole is a high-thickness-diameter ratio through hole; removing glue, depositing copper and electroplating the first through hole; and removing the PTFE film, removing glue, depositing copper and electroplating the first hole to be electroplated, and electroplating the first through hole. In the embodiment of the application, the first hole to be electroplated is protected by the PTFE film, so that the first hole to be electroplated is not attacked when the first through hole is subjected to photoresist removal; and a PTFE film is attached to the copper-clad surface of the copper-clad plate, so that the condition that the thickness of the surface copper is increased during electroplating or flash plating of the first through hole is avoided. Therefore, the processes of copper reduction dry film, lamination copper reduction, etching film stripping, ceramic grinding and the like can be reduced, the uniformity of copper thickness and line width of the surface copper can be conveniently controlled, and the scrapping such as etching open circuit and the like is reduced.

Description

PCB manufacturing method and PCB with high thickness-to-diameter ratio

Technical Field

The application relates to the technical field of PCBs (Printed Circuit Board, printed circuit boards), in particular to a PCB manufacturing method with high thickness-to-diameter ratio and a PCB.

Background

In the related art, when the through blind hole electroplating is carried out on the PCB with the high thickness-diameter ratio (the thickness-diameter ratio is more than 12:1), the electroplating is carried out on the split flow of the through blind hole because the thickness-diameter ratio of the through hole is larger, and the electroplating is carried out on the split flow of the through blind hole; meanwhile, the deep plating capability of the high thickness-to-diameter ratio through hole is poorer (generally less than 80%), the copper thickness after electroplating is quite large (generally more than 80 mu m), and in order to enable the surface copper thickness to meet the requirement, the processes of adding and removing copper dry films, laminating and reducing copper, etching and stripping, ceramic grinding and the like are required. In addition, the conventional process is easy to cause the problems of extremely poor copper thickness (usually extremely poor is more than 20 mu m) on the surface, exposed substrate after grinding, poor uniformity of etched circuits, even scrapping of open and short circuits and the like.

When the PCB with high thickness-to-diameter ratio (thickness-to-diameter ratio is more than 12:1) is selectively plugged, the plugging distance is smaller because the distance between the plug holes and the non-plug holes is smaller, and the non-plug holes are plugged into oil and the dry films fall off when the dry film method is adopted for selectively plugging, so that the plug holes are required to be separated. After plugging, ceramic grinding is needed, and the process after splitting is needed to be plated twice. The deep plating capability of the high thickness-diameter ratio through hole is poorer (generally less than 80%), the copper thickness after electroplating is quite large (generally more than 80 mu m), and in order to ensure that the surface copper thickness meets the use requirement, the processes of adding and removing copper dry films, laminating and reducing copper, etching and stripping and ceramic grinding are required after electroplating. In addition, the conventional process also causes the problems of extremely poor copper thickness (usually extremely poor is more than 20 mu m), exposed substrate, etched circuit uniformity, poor even open and short circuit rejection and the like after polishing.

When the PCB with the high thickness-diameter ratio (the thickness-diameter ratio is more than 12:1) is plated with small holes and large holes or slotted holes, the problem of excessive glue removal easily occurs during glue removal due to the fact that the thickness-diameter of the large holes or slotted holes is smaller. Therefore, when plating small holes, large holes or slots on a PCB with a high thickness-to-diameter ratio, it is generally necessary to perform the split plating process for plating twice. Because the deep plating capability of the small holes with high thickness-diameter ratio is poor (generally less than 80%), the copper thickness after electroplating is very large (generally more than 80 mu m), and in order to ensure that the surface copper thickness meets the use requirement, the small holes are electroplated and then are subjected to the processes of adding and removing copper dry films, laminating and removing copper, etching and removing films, grinding ceramic plates and the like. In addition, the conventional process also causes the problems of extremely poor copper thickness (usually extremely poor more than 20 mu m) on the surface, exposed substrate after grinding, poor uniformity of etched circuits, even scrapping of open and short circuits and the like.

Disclosure of Invention

The present application aims to solve at least one of the technical problems existing in the prior art. Therefore, the PCB manufacturing method and the PCB can reduce the electroplating flow, and effectively reduce the increase of the surface copper thickness in the electroplating process.

According to an embodiment of the application, the method for manufacturing the PCB with the high thickness-to-diameter ratio comprises the following steps:

providing a copper-clad plate, and attaching a PTFE film to the copper-clad surface of the copper-clad plate, wherein the copper-clad plate is provided with a first hole to be electroplated and a first through hole, and the first through hole is a high-thickness-diameter ratio through hole;

removing glue, depositing copper and electroplating the first through hole;

and removing the PTFE film, removing glue, depositing copper and electroplating the first hole to be electroplated, and electroplating the first through hole.

The method for manufacturing the PCB with the high thickness-to-diameter ratio has the following beneficial effects: the PTFE film has the functions of acid and alkali resistance, plasma resistance, chemical photoresist removal, copper precipitation resistance and electroplating, and has the buffer protection function; protecting the first hole to be electroplated by using a PTFE film, so that the hole wall of the first hole to be electroplated is not attacked when the first through hole is gummed; meanwhile, the PTFE film is attached to the copper-clad surface of the copper-clad plate, and when the first through hole is electroplated, the plating layer cannot be attached to the copper-clad surface, so that the condition that the thickness of the copper is increased when the first through hole is electroplated is avoided. Therefore, the processes of copper reduction dry film, lamination copper reduction, etching film stripping, ceramic grinding and the like can be reduced, the uniformity of copper thickness and line width of the surface copper can be conveniently controlled, and the scrapping such as etching open circuit and the like can be reduced; in addition, the hole copper is formed after the first through hole is electroplated, so that the hole wall of the first through hole is not attacked by liquid medicine when the glue of the first hole to be electroplated is removed.

Further, the first hole to be electroplated comprises a common blind hole, a deep micro blind hole or a combined structure of the common blind hole and the deep micro blind hole, and the first hole to be electroplated is processed in a laser drilling mode; or the first hole to be electroplated is a slotted hole or a large hole.

Further, after the PTFE film is attached to the copper-clad surface of the copper-clad plate, mechanical drilling is directly conducted on the PTFE film, so that the first through hole is machined.

In another aspect, the method for manufacturing the PCB with the high thickness-to-diameter ratio according to the embodiment of the application comprises the following steps:

providing a copper-clad plate, wherein the copper-clad plate is provided with a non-hole-plugging through hole and a hole-plugging through hole; a PTFE film is attached to the copper-clad surface of the copper-clad plate; windowing is carried out at the position of the PTFE film corresponding to the hole plugging through hole, and the hole plugging through hole is subjected to photoresist removal, electroplating and resin hole plugging; removing the PTFE film, and removing glue, depositing copper and electroplating the non-plugged through holes to obtain a target PCB; or,

providing a copper-clad plate, wherein the copper-clad plate is provided with a second hole to be electroplated and a third hole to be electroplated, and the aperture of the second hole to be electroplated is smaller than that of the third hole to be electroplated; a PTFE film is attached to the copper-clad surface of the copper-clad plate; windowing is carried out at the position of the PTFE film corresponding to the second hole to be electroplated, and photoresist removal and electroplating are carried out on the second hole to be electroplated; and removing the PTFE film, removing glue, depositing copper and electroplating the third hole to be electroplated, and electroplating the second hole to be electroplated to obtain the target PCB.

Further, the non-hole plugging through hole and the hole plugging through hole are processed at one time; or the second hole to be electroplated and the third hole to be electroplated are processed at one time.

Further, the third hole to be electroplated is a slotted hole or a large hole.

Further, in the case of windowing, the PTFE film is windowed by laser ablation.

Further, when the PTFE membrane is windowed, the size of the windowed region is smaller than the pore diameter of the pore at the corresponding position.

Further, when the PTFE film is removed, manual film tearing or film stripping is performed by a film stripping machine.

Further, in the process of removing the glue, plasma glue removal or chemical glue removal is adopted.

The PCB of the embodiment of the further aspect of the application is manufactured by adopting the manufacturing method of the PCB with the high thickness-to-diameter ratio.

Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the application.

Drawings

The application is further described with reference to the accompanying drawings and examples, in which:

FIG. 1 is a schematic flow chart of electroplating a through blind hole of a PCB with a high thickness-to-diameter ratio manufactured by adopting a prior art method;

FIG. 2 is a schematic flow chart of a prior art method for fabricating a PCB with high aspect ratio for selective plugging;

FIG. 3 is a schematic flow chart of electroplating for manufacturing small holes, large holes or slots of a PCB with high thickness-to-diameter ratio by adopting the prior art method;

fig. 4 is a flowchart of a method for manufacturing a high aspect ratio PCB according to an embodiment of the present application;

FIG. 5 is a flow chart of the method for fabricating the PCB with high aspect ratio in FIG. 4;

fig. 6 is a flow chart of a method for fabricating a high aspect ratio PCB according to an embodiment of the present application;

FIG. 7 is a flow chart of the method for fabricating the PCB with high aspect ratio in FIG. 6;

FIG. 8 is a flow chart of a method of fabricating a high aspect ratio PCB in accordance with an embodiment of the present application;

fig. 9 is a flow chart of the method for manufacturing the high aspect ratio PCB in fig. 8.

Reference numerals:

100. copper-clad plate; 110. a first hole to be plated; 120. a first through hole; 130. a through hole is not plugged; 140. plugging the through hole; 150. a second hole to be electroplated; 160. a third hole to be electroplated;

200.PTFE membranes.

Detailed Description

Embodiments of the present application are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only for the purpose of explaining the present application and are not to be construed as limiting the present application.

In the description of the present application, it should be understood that references to orientation descriptions, such as directions of up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the drawings, are merely for convenience of describing the present application and simplifying the description, and do not indicate or imply that the apparatus or element referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present application.

In the description of the present application, the meaning of a number is one or more, the meaning of a number is two or more, and greater than, less than, exceeding, etc. are understood to exclude the present number, and the meaning of a number above, below, within, etc. are understood to include the present number. The description of the first and second is for the purpose of distinguishing between technical features only and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.

In the description of the present application, unless explicitly defined otherwise, terms such as arrangement, installation, connection, etc. should be construed broadly and the specific meaning of the terms in the present application can be reasonably determined by a person skilled in the art in combination with the specific contents of the technical solution.

In the description of the present application, a description with reference to the terms "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Referring to FIG. 1, when the through blind hole electroplating is performed on a PCB with high thickness-to-diameter ratio (thickness-to-diameter ratio > 12:1), the conventional process method generally comprises the following steps: laser drilling, removing glue, depositing copper, filling holes, electroplating, mechanically drilling, removing glue, depositing copper, electroplating, reducing copper dry film, exposing, developing, reducing copper, removing film, grinding ceramic plate, and pre-treating outer layer.

As can be seen from the above-mentioned processes, when the thickness and diameter of the through hole are relatively large (thickness-diameter ratio is more than 12:1), electroplating is required to be performed through the blind hole splitting process, and two electroplating processes are required to be performed after splitting. Meanwhile, in order to ensure the thickness of the surface copper, the processes of adding a copper-removing dry film, laminating and reducing copper, etching and removing the film, grinding the ceramic plate and the like are needed. In addition, the process can cause the problems of extremely poor copper thickness (usually extremely poor more than 20 mu m) on the surface, exposed substrate after grinding, poor uniformity of etched circuits, even rejection of open and short circuits and the like.

In this regard, an embodiment of one aspect of the present application discloses a method for manufacturing a PCB with a high aspect ratio, see fig. 4 and fig. 5, including the following steps:

s110: providing a copper-clad plate 100, and attaching a PTFE film 200 on the copper-clad surface of the copper-clad plate 100; the copper-clad plate 100 has a first hole to be electroplated 110 and a first through hole 120, wherein the first through hole 120 is a high thickness-to-diameter ratio through hole, i.e. the thickness-to-diameter ratio is greater than 12:1.

Specifically, the copper-clad plate 100 may be a double-layer plate or a multi-layer plate, and one or two surfaces of the outermost side of the copper-clad plate 100 are copper-clad surfaces (i.e., surface copper). When both surfaces of the copper-clad laminate 100 are copper-clad surfaces, each copper-clad surface is bonded with the PTFE film 200. The PTFE film 200 has the characteristics of easy adhesion, no residue after tearing, and the like, and the PTFE film 200 can be pasted by a machine by adopting a manual film pasting or a film pasting machine. The plating position of the plate edge is exposed during film lamination, and the rest positions are covered with the PTFE film 200.

Note that the thickness of the PTFE film 200 may be selected according to the plate thickness of the copper-clad plate 100. Illustratively, the thickness of the PTFE membrane 200 may be selected to be in the range of 0.1 to 0.5mm.

In one embodiment, the first hole to be plated 110 may be a common blind hole, a deep blind hole, or a combination of a common blind hole and a deep blind hole. The first hole to be plated 110 may be processed by laser drilling, where laser drilling parameters are selected according to the aperture, the thickness-to-diameter ratio, and the dielectric Tg point of the first hole to be plated 110.

S120: the first via 120 is stripped, copper deposited, and plated.

It should be appreciated that the number of first through holes 120 may be one or more, and is not limited herein. Similarly, the number of the first holes 110 to be plated can be designed according to the requirement.

Plasma desmear and/or chemical desmear may be used to desmear the first via 120. Because the PTFE membrane 200 material is chemically inert and does not participate in the reaction during the plasma photoresist removal and the chemical photoresist removal, the PTFE membrane 200 can protect the walls of the first hole 110 to be plated from being attacked by the plasma and the chemical photoresist remover during the photoresist removal. Meanwhile, the PTFE film 200 has an anti-copper deposition effect, and is not deposited with a layer of copper like other common dry films and inks, so that the surface copper is not plated with a layer of copper when the first through hole 120 is plated, which is beneficial to controlling the thickness of the surface copper.

Wherein, the electroplating parameters can be selected according to the thickness of the hole copper. In this embodiment, the first through hole 120 is electroplated, mainly by plating a layer of thin copper, the thickness of the thin copper is usually 5-10 μm, so that the hole wall of the first through hole 120 is not attacked by plasma or photoresist remover when the blind hole is photoresist removed.

In one embodiment, the first via 120 may also be flash plated such that the first via 120 is plated with a thin layer of copper.

S130: the PTFE film 200 is removed, the first hole 110 to be plated is subjected to photoresist removal, copper deposition, and hole filling plating, and the first through hole is plated.

Specifically, after removing the PTFE film 200, the first hole to be plated 110 is subjected to photoresist removal, and the photoresist removal parameter is selected according to the thickness-to-diameter ratio and the dielectric Tg point of the first hole to be plated 110. Since the first through hole 120 is already plated with a layer of thin copper, the thin copper can prevent the first through hole 120 from being eroded by plasma and photoresist remover when the first hole 110 to be plated is photoresist-removed. After the photoresist is removed, copper deposition and hole filling electroplating are performed on the first hole 110 to be electroplated, and the hole filling electroplating parameters are selected according to the aperture of the blind hole, the thickness of the medium and the thickness-to-diameter ratio. The first through-hole 120 is subjected to the second plating while the first hole 110 to be plated is subjected to the plating. Since the first through-hole 120 is already plated with thin copper, the deep plating capability of the first through-hole 120 can be improved, so that the plating thickness of the inner wall of the first through-hole 120 is uniformly increased.

In the foregoing embodiment, the average hole wall copper thickness of the first through hole 120 is greater than 25 μm, and the minimum copper thickness of a single point is greater than 20 μm. And after the first hole 110 to be electroplated is filled and electroplated, the outer layer pattern is normally manufactured. In the whole process, the surface copper is electroplated once, so that the thickness and uniformity of the surface copper can be well controlled, and the processes of copper reduction dry film, lamination copper reduction, etching film stripping, ceramic grinding and the like are not needed, thereby being beneficial to saving the process. Meanwhile, when the outer layer pattern is manufactured, the problem of open and short circuit rejection caused by excessive etching or incomplete etching is not easy to occur because the copper thickness of the surface copper is extremely small.

In one embodiment, after the PTFE film 200 is attached to the copper-clad surface of the copper-clad plate 100, the copper-clad plate 100 is directly mechanically drilled on the PTFE film 200 to form the first through hole 120.

Specifically, drilling parameters of the mechanical drilling may be selected according to the Tg point of the material, the thickness-to-diameter ratio of the first through hole 120, the material filler ratio, and the like. Because the PTFE film 200 has a very high Tg point (> 300 ℃) and the PTFE film 200 has flame retardant properties, the PTFE film 200 does not burn as well as ordinary dry films and inks after drilling, and the PTFE film 200 can buffer and protect the plate surface after covering the orifice position of the first through hole 120. Thus, after the PTFE film 200 is attached to the surface of the copper-clad plate 100, mechanical drilling can be directly performed at the position where the PTFE film 200 is attached to the copper-clad plate 100, and the problem of burrs and the like are not easy to occur at the position of the orifice of the first through hole 120.

In other embodiments, the first through-hole 120 may also be processed prior to the PTFE film 200 being applied. After the PTFE film 200 is adhered to the copper-clad surface, the position of the PTFE film 200 corresponding to the first through hole 120 is windowed, and then the first through hole 120 is subjected to photoresist removal, copper deposition and electroplating.

In other embodiments, the first hole 110 to be plated may be a slot or a large hole (i.e. the hole diameter is larger than 3 mm), and other manufacturing steps are described above, which will not be repeated here.

As shown in fig. 2, when the PCB with high thickness-to-diameter ratio (thickness-to-diameter ratio > 12:1) is selectively plugged, the conventional process method generally includes the following steps: the method comprises the steps of first drilling, removing glue, depositing copper, filling holes, electroplating, resin plugging, ceramic grinding, second drilling, removing glue, depositing copper, filling holes, reducing copper dry film, exposing, developing, reducing copper, removing film, ceramic grinding, outer layer pretreatment and the like. In the process method, the hole plugging and non-hole plugging are needed to be split when the distance between the hole plugging and the non-hole plugging is short, and the split process needs to be performed with two electroplating steps, wherein the thickness of copper after the two electroplating steps is very large (generally more than 80 mu m). In order to enable the thickness of the surface copper to meet the requirement, the processes of adding a copper-removing dry film, laminating and reducing copper, etching and removing the film and grinding the ceramic plate are required after electroplating. In addition, the process flow also easily causes the problems of extremely poor copper thickness (usually extremely poor more than 20 mu m) on the surface, exposed base material after grinding, poor uniformity of the etched circuit, even rejection of open and short circuit and the like.

In this regard, another embodiment of the present application discloses a method for manufacturing a PCB with a high aspect ratio, referring to fig. 6 and fig. 7, including the following steps:

s210: a copper-clad laminate 100 is provided, the copper-clad laminate 100 having non-through hole-plugging through holes 130 and through hole-plugging through holes 140.

Specifically, the copper-clad plate 100 may be a double-layer plate or a multi-layer plate, and one or two surfaces of the outermost side of the copper-clad plate 100 are copper-clad surfaces.

In some embodiments of the present application, the non-through-hole via 130 and the through-hole via 140 are machined at one time. Therefore, one-time drilling can be saved, and the manufacturing efficiency is improved. Further, the borehole may be a mechanical borehole. The drilling parameters may be selected according to the Tg point of the material, the thickness-to-diameter ratio of the non-plugged through-holes 130 and the plugged through-holes 140, the filling ratio of the plugged material, and the like.

S220: PTFE films 200 were bonded to both surfaces of the copper-clad laminate 100.

Specifically, the PTFE film 200 is attached to the copper-clad plate 100 after drilling. The PTFE film 200 has the characteristics of easy adhesion, no residue after tearing, and the like, and can be easily removed. In attaching the PTFE film 200, the machine lamination may be performed by using a manual lamination or a laminator. In the film pasting, the plating position of the plate edge is exposed, and the rest positions are covered with the PTFE film 200.

It should be appreciated that the thickness of the PTFE film 200 may be selected according to the thickness of the copper-clad laminate 100. Illustratively, the thickness of the PTFE membrane 200 may be selected to be in the range of 0.1mm to 0.5mm.

S230: the PTFE film 200 is windowed at a position corresponding to the via hole 140, and the via hole 140 is subjected to photoresist removal, electroplating, and resin via hole.

In the case of windowing, the PTFE film 200 may be windowed by laser ablation. Further, when the PTFE membrane 200 is windowed, the size of the windowed region is smaller than the aperture of the hole at the corresponding position, so that an offset margin is left between the windowed region and the edge of the hole, and the windowed region is prevented from being windowed onto the surface copper. Thus, the surface copper can be effectively protected.

It is understood that the laser parameters may be selected based on PTFE, film thickness, and window size.

In one embodiment, the PTFE film 200 is laser windowed after lamination, wherein the pore diameter of the via hole 140 is D, and the window size is D-25 μm to D-50 μm. Thus, the window is slightly smaller than the aperture of the via hole 140, so that enough offset allowance can be ensured to ensure that the window cannot open to the surface copper.

After the laser windows, the via holes 140 are glued, and specifically, plasma glue removal, chemical glue removal and other modes can be adopted for glue removal. The PTFE membrane 200 material is chemically inert and does not participate in the reaction during the plasma photoresist removal and the chemical photoresist removal, thus protecting the walls of the via holes 140 from being attacked by the plasma and the chemical photoresist remover. The PTFE film 200 has an anti-copper deposition effect and is not deposited with a layer of copper like other common dry films and inks, so that the surface copper can be protected during the electroplating of the via hole through hole 140, and the surface copper is not plated with a layer of copper; meanwhile, the PTFE film 200 may also protect the non-plugged through-holes 130 under the PTFE film 200 from being electroplated with a copper layer. Wherein, the electroplating parameters can be selected according to the thickness of the hole copper. In this step, the plating mainly coats the via hole 140 with a thin copper layer, and the thickness of the thin copper layer is 5-10 μm by way of example, so that the thin copper layer can protect the hole wall of the via hole 140 from being attacked by plasma or photoresist remover when the photoresist is removed from the via hole 130.

After the completion of the plating of the via hole 140, the region of the via hole 140 is subjected to resin via hole. The hole plugging can be performed by adopting a vacuum hole plugging process. Because the PTFE film 200 has a good bonding force with the surface copper, when the PTFE film 200 is used for selectively plugging and the distance between the plugged through-holes 140 and the unplugged through-holes 130 is less than or equal to 250 μm, the problems similar to the dry film falling and the oil entering of the unplugged area will not occur like the dry film method. In addition, the PTFE film is attached to the surface of the copper-clad plate 100, the PTFE film 200 can be directly removed after plugging, and the operations such as ceramic grinding and the like are not needed like a dry film method, so that the process flow is saved, and the flatness of the surface copper is also guaranteed.

S240: the PTFE film 200 is removed, and the non-plugged vias 130 are gummed, copper deposited, and electroplated to obtain the target PCB.

Wherein, the step of removing the PTFE film 200 can adopt manual film tearing or film stripping by a film stripping machine; when the glue is removed, plasma glue removal, chemical glue removal and other modes can be adopted for removing the glue.

In this embodiment, after removing the PTFE film 200, the non-plugged through-hole 130 is removed, and the parameter of removing the glue may be selected according to the thickness-to-diameter ratio of the non-plugged through-hole 130 and the dielectric Tg point. Since the via hole 140 has been plated with a thin copper layer, the thin copper protects the via hole 140 from being attacked by plasma and photoresist remover when the via hole 130 is not photoresist removed. After the photoresist is removed, copper deposition and hole electroplating are carried out on the non-hole-plugging through holes 130, and electroplating parameters are selected according to the aperture, the hole area and the thickness-diameter ratio of the non-hole-plugging through holes 130.

In some embodiments, the average pore wall copper thickness of the non-plugged vias 130 is greater than 25 μm, and the minimum copper thickness at a single point is greater than 20 μm. After the non-plug hole through hole 130 is electroplated, the outer layer pattern is normally manufactured. Because the surface copper is electroplated once, the thickness and uniformity of the surface copper can be well controlled, and the processes of copper reduction dry film, lamination copper reduction, etching film stripping, ceramic grinding and the like are not needed. Because copper thickness is extremely small, the problem of open and short circuit rejection caused by excessive etching or incomplete etching is not easy to occur when the outer layer pattern is manufactured.

As shown in FIG. 3, when the PCB with high thickness-to-diameter ratio (thickness-to-diameter ratio > 12:1) is plated with small holes and large holes or slots, the conventional process method comprises the following steps: the method comprises the steps of first drilling, removing glue, depositing copper, flash plating, electroplating thickening, reducing copper dry film, exposing, developing, reducing copper, removing film, grinding a ceramic plate, second drilling, removing glue, depositing copper, electroplating, grinding the ceramic plate, outer layer pretreatment and the like. In the process method, as the thickness diameter of the large holes or the slotted holes is smaller, the problem of excessive photoresist removal easily occurs during photoresist removal, and the split electroplating process is usually carried out for two times of electroplating. The thickness of copper after electroplating is very large (generally more than 80 mu m), and in order to ensure that the thickness of the surface copper meets the requirement, the processes of adding and subtracting a copper dry film, laminating and subtracting copper, etching and removing the film, grinding a ceramic plate and the like are required after the first small hole electroplating. In addition, the conventional process also causes the problems of extremely poor copper thickness (usually extremely poor more than 20 mu m) on the surface, poor uniformity of exposed base materials and etched circuits, and even scrapping of open and short circuits after grinding the plates.

In this regard, another embodiment of the present application discloses a method for manufacturing a PCB with a high aspect ratio, referring to fig. 8 and 9, including the following steps:

s310: the copper-clad plate 100 is provided, the copper-clad plate 100 is provided with a second hole 150 to be electroplated and a third hole 160 to be electroplated, and the aperture of the second hole 150 to be electroplated is smaller than that of the third hole 160 to be electroplated.

Wherein, the copper-clad plate 100 can be a double-layer plate or a multi-layer plate, and one or two surfaces of the outermost side of the copper-clad plate 100 are copper-clad surfaces; the third holes to be plated 160 are slots or macropores. It should be noted that macropores refer to pores having a pore diameter of greater than 3.0 mm.

In some embodiments of the present application, the second hole to be plated 150 and the third hole to be plated 160 are processed at one time. Therefore, one-time drilling flow can be saved, the manufacturing efficiency is improved, and the drilling cost is reduced.

S320: the PTFE film 200 is bonded to the copper-clad surface of the copper-clad plate 100.

S330: and (3) windowing is carried out at the position of the PTFE film 200 corresponding to the second hole 150 to be electroplated, and the second hole 150 to be electroplated is subjected to photoresist removal and electroplating.

In some embodiments of the present application, the PTFE film 200 may be windowed using laser ablation. Further, when the PTFE membrane 200 is windowed, the size of the windowed region is smaller than the aperture of the second hole 150 to be plated at the corresponding position. Thus, the situation of opening copper to the surface during window opening can be reduced, and the surface of the copper-clad plate 100 can be protected.

S340: the PTFE film 200 is removed, the third hole to be plated 160 is subjected to photoresist removal, copper deposition and plating, and the second hole to be plated 150 is subjected to plating to obtain a target PCB.

In some embodiments of the present application, the step of removing the PTFE membrane 200 may be performed using a manual membrane stripping process or using a membrane stripping machine.

In this embodiment, the PTFE film 200 has the functions of acid and alkali resistance, plasma resistance, chemical photoresist removal, copper deposition resistance, and electroplating, and the PTFE film 200 also has the buffer protection function. The PTFE film 200 is used to protect the third hole 160 to be plated, so that the third hole 160 to be plated is not attacked by plasma or photoresist remover when the second hole 150 to be plated is photoresist removed. Because the surface copper is electroplated once, the thickness and uniformity of the surface copper can be well controlled, and the processes of copper reduction dry film lamination, copper reduction, etching film stripping, ceramic grinding and the like are not needed. When the outer layer pattern is manufactured, the problem of open and short circuit rejection caused by excessive etching or incomplete etching is not easy to occur because the copper thickness is extremely small.

In the foregoing embodiment, the photoresist may be removed by plasma photoresist removal, chemical photoresist removal, or the like.

In another aspect, the present application discloses a PCB manufactured using the method for manufacturing a PCB with a high aspect ratio as described above. In the PCB of the embodiment of the application, the copper thickness of the surface copper can be effectively controlled, and the extremely poor copper thickness is small. When the outer layer pattern is manufactured, the problem of open and short circuit scrapping caused by excessive etching or incomplete etching is not easy to occur, and the quality of the PCB is improved.

The embodiments of the present application have been described in detail above with reference to the accompanying drawings, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge of one of ordinary skill in the art without departing from the spirit of the present application. Furthermore, embodiments of the present application and features of the embodiments may be combined with each other without conflict.

Claims

1. The manufacturing method of the PCB with the high thickness-to-diameter ratio is characterized by comprising the following steps of:

removing glue, depositing copper and electroplating the first through hole;

2. The method for manufacturing a high aspect ratio PCB according to claim 1, wherein,

the first hole to be electroplated comprises a common blind hole, a deep blind hole or a combined structure of the common blind hole and the deep blind hole, and the first hole to be electroplated is processed in a laser drilling mode; or the first hole to be electroplated is a slotted hole or a large hole.

3. The method for manufacturing a high-thickness-to-diameter-ratio PCB according to claim 2, wherein after the PTFE film is attached to the copper-clad surface of the copper-clad plate, mechanical drilling is directly performed on the PTFE film to process the first through hole.

4. The manufacturing method of the PCB with the high thickness-to-diameter ratio is characterized by comprising the following steps of:

5. The method for manufacturing a high aspect ratio PCB according to claim 4, wherein the non-plugged through-holes and the plugged through-holes are processed at one time; or the second hole to be electroplated and the third hole to be electroplated are processed at one time.

6. The method of claim 4, wherein the PTFE film is windowed by laser ablation.

7. The method of claim 4 or 6, wherein the size of the window area is smaller than the pore diameter of the corresponding hole when the PTFE film is windowed.

8. The method of claim 4, wherein the PTFE film is removed by manually peeling the film or peeling the film using a peeling machine.

9. The method of claim 4, wherein plasma or chemical photoresist is used in photoresist stripping.

10. A PCB manufactured by the method of manufacturing a high aspect ratio PCB according to any one of claims 1 to 3; or, the method for manufacturing the high-thickness-diameter-ratio PCB according to any one of claims 4 to 9 is adopted.