CN118450609A - Laser drilling substrate preparation method and printed circuit board - Google Patents

Abstract

The invention relates to a preparation technology of a printed circuit board, and particularly discloses a preparation method of a laser drilling substrate and a corresponding printed circuit board, which can effectively remove suspended copper. The method comprises the following steps: before laser drilling, pasting a dry film on the whole substrate, and carrying out whole-plate exposure to cure the dry film on the whole substrate; performing laser drilling on the whole substrate after the dry film is solidified; etching the suspended copper generated in the substrate integral holes; and (3) performing film removing treatment on the whole etched substrate to obtain the laser drilling substrate without suspended copper.

Description

Laser drilling substrate preparation method and printed circuit board

Technical Field

The invention relates to the technical field of circuit board manufacturing, in particular to a laser drilling substrate preparation method and a printed circuit board.

Background

In the fabrication of printed circuit boards (Printed Circuit Board, PCBs), etc., laser driller processing is typically required to obtain the desired holes.

At present, when the blind holes and the through holes are drilled by the traditional laser drilling, suspended copper is generated, when the laser drilling is performed, the copper foil is lower than the resin/glass fiber on the substrate in laser drilling, so that the size of the copper holes on the surface is different from that of the resin holes in the substrate, wherein the protruding copper foil is called suspended copper, and after plasma (plasma cleaning) and copper deposition processes, the length of the suspended copper is further enlarged. The generation of the suspended copper can cause the defect of hole filling such as hole filling concave and hole filling cavity and the like due to poor replacement rate of the liquid medicine in the hole when the substrate is filled, and the defect risk of annular short circuit is more caused if the suspended copper is too large.

Disclosure of Invention

Based on this, it is necessary to provide a laser drilling substrate preparation method and a printed circuit board to solve the problem of hole filling risk caused by copper suspension in the substrate in the prior art.

In a first aspect, a method for preparing a laser drilling substrate is provided, including:

before laser drilling, pasting a dry film on the whole substrate, and carrying out whole-plate exposure to cure the dry film on the whole substrate;

Performing laser drilling on the whole substrate after the dry film is solidified;

etching the suspended copper generated in the substrate integral holes;

and (3) performing film removing treatment on the whole etched substrate to obtain the laser drilling substrate without suspended copper.

Optionally, the pasting the dry film on the whole board of the substrate and carrying out the whole board exposure to cure the dry film on the whole board of the substrate includes:

And pasting dry films on the whole substrate and exposing the whole substrate to solidify the dry films at all positions on the whole substrate.

Optionally, before etching the suspended copper generated in the substrate integral hole, the method further includes:

and (3) hole cleaning is carried out on the drilled holes of the whole substrate after laser drilling, so that residual compounds on the whole substrate are cleaned.

Optionally, the hole cleaning is performed on the drilled holes of the whole substrate after the laser drilling, so that the residual compound on the whole substrate is cleaned, and the method comprises the following steps:

And (3) drilling the whole substrate after laser drilling to clean PLASMA holes so as to remove residual compounds on the whole substrate.

Optionally, the bore comprises a through hole and/or a blind hole.

Optionally, the dry film comprises a UV dry film or an LDI dry film.

Optionally, the attaching the dry film to the whole substrate includes:

and pasting a dry film on the surface copper layer of the upper plate surface and/or the lower plate surface of the whole substrate.

Optionally, the dry film has a thickness of 10 to 20 microns.

Optionally, the etching the suspended copper generated in the substrate integral hole includes:

and etching the suspended copper generated in the whole hole of the substrate by adopting acid liquor.

In a second aspect, a printed circuit board is provided, comprising a laser drilled substrate prepared by the laser drilled substrate preparation method according to any one of the preceding claims.

In any one of the above provided schemes, compared with the traditional laser drilling scheme, the dry film on the whole substrate is solidified due to the fact that the dry film is pasted on the whole substrate and the whole substrate is exposed before laser drilling; directly carrying out laser drilling on the whole substrate after the dry film is solidified, and suspending copper at the moment; etching the suspended copper generated in the whole hole of the substrate so as to eliminate the suspended copper; and performing film removing treatment on the whole etched substrate to obtain the laser drilling substrate without suspended copper, which can be used in the subsequent manufacturing process. The method and the device can effectively eliminate suspended copper existing in the laser drilling process, so that hole filling defects such as hole filling pits and hole filling hollows of the substrate are effectively reduced or avoided, or defect risk situations of annular short circuit are caused.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the description of the embodiments of the present invention will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic illustration of a process flow of a method for fabricating a laser drilled substrate according to an embodiment of the present invention;

fig. 2 is a schematic diagram of another preparation process of a laser drilling substrate preparation method according to an embodiment of the invention.

Detailed Description

In order to make the technical problems, technical schemes and beneficial effects solved by the invention more clear, the invention is further described in detail below with reference to the accompanying drawings and embodiments.

It is to be understood that the embodiments set forth below represent the necessary information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims.

It will be further understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present disclosure. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

It will also be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present.

It will be further understood that the terms "upper," "lower," "left," "right," "front," "rear," "bottom," "middle," "top," and the like may be used herein to describe various elements and that the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the drawings merely to facilitate describing the invention and simplifying the description, and do not indicate or imply that the devices or elements being referred to must have a particular orientation, be constructed and operate in a particular orientation, and that these elements should not be limited by these terms.

These terms are only used to distinguish one element from another element. For example, a first element could be termed a "upper" element, and, similarly, a second element could be termed a "upper" element, depending on the relative orientation of the elements, without departing from the scope of the present disclosure.

It will be further understood that the terms "comprises," "comprising," "includes" and/or "including," when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Unless defined otherwise, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

The first aspect of the present application provides a method for preparing a gold plated auxiliary lead, as shown in fig. 1, comprising the steps of:

s101: before laser drilling, pasting a dry film on the whole substrate, and carrying out whole-plate exposure to cure the dry film on the whole substrate;

s102: performing laser drilling on the whole substrate after the dry film is solidified;

s103: etching the suspended copper generated in the substrate integral holes;

S104: and (3) performing film removing treatment on the whole etched substrate to obtain the laser drilling substrate without suspended copper.

The substrate is a basic material for manufacturing a PCB board, typically, the substrate is a Copper clad laminate, and in manufacturing, single-sided and double-sided printed boards are generally manufactured by selectively performing hole processing, electroless Copper plating, electrolytic Copper plating, etching and other processes on a substrate material, namely, a Copper clad laminate (coppers CLAD LAMINATE, CCL), to obtain a required circuit pattern. The performance, quality, workability in manufacturing, manufacturing cost, manufacturing level, etc. of the printed board depend to a large extent on the substrate material. The hole processing of the substrate typically employs laser drilling, which illustratively includes blind holes and/or through holes. In this embodiment, the laser drilling process of the substrate is mainly improved.

Firstly, before laser drilling, pasting a dry film on a whole substrate, and carrying out whole exposure to enable the dry film on the whole substrate to be cured. When the film is stuck on the whole substrate, a dry film is stuck on the whole substrate, namely, the surface of the substrate is covered with the film. It should be further understood that the Dry film is a polymer material that can generate a polymerization reaction after irradiation of ultraviolet rays to form a stable substance attached to the surface of the substrate, thereby achieving the function of blocking electroplating and etching, with respect to the Wet film. As an example, in the present application, the dry film may include a UV dry film or an LDI dry film, or other equivalent alternative dry films, without being limited thereto.

It should be noted that, in some embodiments, depending on the drilling requirements, the dry film may be applied to the upper surface and/or the lower surface of the entire substrate, where the dry film may be applied to the upper surface and/or the lower surface of the entire substrate, depending on the type of drilling, for example, if only the upper surface of the substrate is drilled with a blind hole, the corresponding upper surface of the substrate may be attached to the entire substrate, which is not limited in particular. For example, as shown in fig. 2, a layer of dry film is respectively attached to the copper layers on the upper/lower surfaces of the substrate, and then the dry film is exposed to light to cure the dry film on the entire substrate. In addition, as an example, the thickness of the dry film may be 10 to 20 micrometers, and is not particularly limited.

In addition, as an example, the drilling process flow of the present application may be performed simultaneously on the upper and lower surfaces of the substrate, and may be performed simultaneously on both surfaces of the substrate, thereby improving the processing efficiency.

The dry film is pasted, namely, the dry film in a molten flow state is filled on the copper surface of the conductive layer of the substrate, so that the dry film is flatly pasted on the surface of the substrate; the exposure can be performed by irradiating the film with ultraviolet light (UV light) to polymerize the dry film in the irradiated portion and change it into a resist layer.

With continued reference to fig. 2, after the dry film of the whole substrate is cured, the method is different from the conventional method in that the developing process is skipped, that is, the dry film is not subjected to the next developing process; and directly carrying out laser drilling on the whole substrate after the dry film is solidified. After the dry film on the whole substrate is directly subjected to laser drilling treatment, the attached dry film is a high molecular compound and is close to the absorption rate of the substrate (generally comprising resin/glass fiber) to light waves, so that after the laser drilling treatment, the surface dry film on the whole substrate is closer to the hole burned by the inner substrate, and the hole size is more consistent; furthermore, copper absorbs less energy due to the absorption of light waves, which is also different from the size of the holes burned out by the substrate/dry film, thus producing suspended copper. In the embodiment of the application, as shown in fig. 2, the suspended copper generated in the whole hole of the substrate is further etched, so that the substrate overetching line body can be protected, and the surface part of the substrate is not bitten off due to the solidified dry film of the copper on the other surface, and only the excessive suspended copper in the hole is bitten off, so that the suspended copper is etched off; and (3) performing film removing treatment on the whole etched substrate to obtain the laser drilling substrate without suspended copper.

Therefore, compared with the traditional laser drilling scheme, the embodiment of the application provides the gold-plated auxiliary lead preparation method which is used for preparing the base plate of various printed circuit boards, and the dry film on the whole base plate is solidified due to the fact that the dry film is pasted on the whole base plate and the whole plate is exposed before laser drilling; directly carrying out laser drilling on the whole substrate after the dry film is solidified, and suspending copper at the moment; etching the suspended copper generated in the whole hole of the substrate so as to eliminate the suspended copper; and performing film removing treatment on the whole etched substrate to obtain the laser drilling substrate without suspended copper, which can be used in the subsequent manufacturing process. The method and the device can effectively eliminate suspended copper existing in the laser drilling process, so that hole filling defects such as hole filling pits and hole filling hollows of the substrate are effectively reduced or avoided, or defect risk situations of annular short circuit are caused.

In an embodiment, in step S10, that is, the step of attaching the dry film to the whole substrate and performing the whole-substrate exposure to cure the dry film on the whole substrate includes: and pasting dry films on the whole substrate and exposing the whole substrate to solidify the dry films at all positions on the whole substrate.

In this embodiment, in order to ensure the drilling effect, the dry film is applied to the whole substrate and the whole substrate is exposed during the process of applying the dry film and exposing, so as to ensure that the dry films at all positions on the whole substrate are cured. Because the dry films at all positions of the whole substrate are cured, the influence of subsequent etching on the surface copper layer can be effectively reduced, and the effect of directly carrying out laser drilling on the cured dry films can be effectively ensured.

Of course, it should be noted that in some embodiments, the hole position where the laser drilling is required on the whole substrate may be determined, and then the peripheral dry film at the hole position is cured, where curing is not required at all positions, so that the process steps are reduced, which is beneficial to improving the processing efficiency, and meanwhile, the completion of the laser drilling is ensured.

In an embodiment, before step S103, that is, before the etching of the suspended copper generated in the substrate plate hole, the method further includes: the whole substrate is drilled by laser to clear holes, so that residual compounds on the whole substrate are cleared, and the aperture reaches the expected size

In the embodiment of the present application, the hole cleaning process may have various manners, and the embodiment of the present application is not limited thereto. As an example, the drilling of the whole substrate after laser drilling is performed to clean the PLASMA hole, so that the residual compound on the whole substrate can be cleaned, and other hole cleaning processes can be also used, which are not limited in particular and are not described one by one. It will be appreciated that in the manufacture of PCB circuit boards, for example, particularly High Density Interconnect (HDI) boards, PLASMA is used for hole cleaning, which requires a metallization process to provide electrical continuity between layers through the metallized holes. Because the residual jelly often adheres to the holes in the case of too high local temperature in the laser drilling process, in order to better avoid the product quality problem in the subsequent metallization process, hole cleaning is required, so that the residual compound on the whole substrate is removed, and the drilling quality can be effectively ensured by matching with the subsequent etching treatment step.

It is also worth to say that, because the current wet process hole cleaning process, such as potassium permanganate solution process, is mostly selected, the liquor is difficult to enter the holes, and the drill dirt removal has a certain limitation. The PLASMA hole cleaning process is used as an ion body for cleaning, is a key application on a printed circuit board, and generally adopts oxygen-carbon tetrafluoride mixed gas as a gas source so as to obtain a good hole treatment effect and improve hole cleaning quality.

In one embodiment, in step S104, the etching the suspended copper generated in the holes of the substrate integral plate includes: and etching the suspended copper generated in the whole hole of the substrate by adopting acid liquor.

In this example, the Sodium Persulfate (SPS) copper etch principle can be used to etch away suspended copper in the hole after laser drilling, and the complete drill control strand is finally revealed. For example, a potassium permanganate solution or other acid solution that etches away suspended copper may be used, but is not particularly limited.

In fig. 2, only the two-sided drilling process is taken as an example, and the process is similar when the drilling process is performed on one side, and the description is not repeated here.

The embodiment of the application also provides a printed circuit board, which comprises the laser drilling substrate prepared by the laser drilling substrate preparation method according to any one of the embodiments.

It should be understood that after the laser drilling substrate is prepared by adopting the preparation method provided by the embodiment of the application, a substrate without suspended copper can be obtained, and then a subsequent PCB preparation process can be performed on the substrate based on the suspended copper according to the PCB preparation requirement, so that the required PCB is obtained. Due to the adoption of the scheme, the copper suspension existing in the substrate in the laser drilling process can be effectively eliminated, so that the hole filling defects such as hole filling pits and hole filling hollows of the obtained PCB are effectively reduced or avoided, or the defect risk condition of annular short circuit is caused, and the quality of finished electronic products is greatly improved.

The above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention, and are intended to be included in the scope of the present invention.

Claims (10)

1. A method of preparing a laser drilled substrate, comprising:

before laser drilling, pasting a dry film on the whole substrate, and carrying out whole-plate exposure to cure the dry film on the whole substrate;

Performing laser drilling on the whole substrate after the dry film is solidified;

etching the suspended copper generated in the substrate integral holes;

and (3) performing film removing treatment on the whole etched substrate to obtain the laser drilling substrate without suspended copper.

2. The method for preparing a laser drilling substrate according to claim 1, wherein the steps of applying a dry film to a whole substrate and exposing the whole substrate to light, and curing the dry film on the whole substrate comprise:

And pasting dry films on the whole substrate and exposing the whole substrate to solidify the dry films at all positions on the whole substrate.

3. The method of claim 1, further comprising, prior to etching the suspended copper generated in the substrate via holes:

and (3) hole cleaning is carried out on the drilled holes of the whole substrate after laser drilling, so that residual compounds on the whole substrate are cleaned.

4. The method for preparing a substrate for laser drilling according to claim 3, wherein the step of cleaning the drilled holes of the whole substrate after the laser drilling to remove the residual compound on the whole substrate comprises the steps of:

And (3) drilling the whole substrate after laser drilling to clean PLASMA holes so as to remove residual compounds on the whole substrate.

5. The method of any of claims 1-4, wherein the drilling comprises through holes and/or blind holes.

6. The method of any one of claims 1-4, wherein the dry film comprises a UV dry film or an LDI dry film.

7. The method of any one of claims 1-4, wherein the dry film has a thickness of 10 to 20 microns.

8. The method of any one of claims 1-4, wherein etching the suspended copper generated in the substrate via holes comprises:

and etching the suspended copper generated in the whole hole of the substrate by adopting acid liquor.

9. The method for preparing a laser-drilled substrate according to any one of claims 1 to 4, wherein the applying a dry film to the whole substrate comprises:

and pasting a dry film on the surface copper layer of the upper plate surface and/or the lower plate surface of the whole substrate.

10. A printed circuit board comprising a laser drilled substrate prepared by the method of preparing a laser drilled substrate according to any one of claims 1-9.