KR100997803B1 - Manufacturing method of PCB - Google Patents

Abstract

Disclosed is a method of manufacturing a printed circuit board. Providing a build-up substrate having circuit patterns and via holes formed in an outer layer; Filling the via holes with solder resist; And a method of manufacturing a printed circuit board including applying a solder resist to a surface of a build-up substrate, by using solder resist as a plugging material, to reduce production cost, and to apply the front surface immediately after filling to thereby plugging ink. The productivity can be improved by eliminating the drying process and the frontal treatment process, which are the main processes applied to the filling method, and the problem of deterioration of the reliability due to the polishing of the plated part of the hole due to the overpolishing can be solved without the need of the frontal treatment of the overfilled plugging ink. Can be.

Plugging, Solder Paste, Squeeze

Description

Manufacturing method of printed circuit board {Manufacturing method of PCB}

The present invention relates to a printed circuit board manufacturing method.

The printed circuit board is formed by laminating and etching copper foil on a substrate made of a material such as paper phenol resin or glass epoxy resin, or forming a circuit pattern through a plating method. Recently, electronic devices are becoming smaller, thinner, lighter, and more compact, and accordingly, the number of plating through holes and via holes has to increase in order to make the multilayer printed circuit board smaller and denser. to be. In addition, chips mounted on multilayer printed circuit boards are also responding to the same trend.

In order to manufacture such a printed circuit board, conventionally, a copper foil-laminated substrate is etched according to a design circuit, and is faced to obtain high smoothness, and then a photo solder resist is applied to one surface by a silk screen or spray method and dried firstly. A photo solder resist was applied to the other surface, and then dried secondly, followed by exposure and drying to complete a printed circuit board. Compared to the spray method, the screen coating method has high adhesion and good surface uniformity. However, the screen coating method does not cover the edge part of the hole, thereby exposing the metal at the edge part of the hole.

In order to solve this problem, the method of applying the photosolder resist twice is used. However, since the edge portion of the hole is still not completely prevented even with this method, plugging ink, which is an insulating material, has recently been used. After filling the hole using a method of applying a photo solder resist is applied. However, the method of filling the hole using the plugging ink requires the use of expensive plugging ink, thereby increasing the manufacturing cost of the substrate and removing the over-plating of the hole in the frontal treatment process of removing the overfilled plugging ink.

The present invention provides a printed circuit board manufacturing method for plugging a via hole using a solder resist.

According to an aspect of the invention, providing a build-up substrate having a circuit pattern and a via hole in the outer layer; Filling the via holes with solder resist; And applying a solder resist to the surface of the build-up substrate.

The via hole includes a through via hole penetrating the builder up substrate, and the filling of the via hole includes filling the through via hole with solder resist in one direction; And filling the through via hole with solder resist in the other surface direction. In addition, the solder resist includes a photosensitive material, after the step of applying the solder resist to the build-up substrate, the step of depositing a mask on the solder resist; The method may further include selectively exposing the surface of the buildup substrate by exposing and developing the solder resist.

The filling of the via hole may include arranging a screen plate having an opening corresponding to the via hole on the build-up substrate; And filling the solder resist into the via hole by pushing the solder resist through the opening of the screen plate.

According to a preferred embodiment of the present invention, by using the solder resist as the plugging material, to reduce the production cost, and to apply the entire surface immediately after filling the drying process and the front surface treatment which is the main process applied to the filling method of plugging ink (plugging ink) The process can be deleted to increase productivity. In addition, since the overfilled plugging ink does not need to be treated in front, the problem of deterioration of reliability due to the polishing of the plated portion of the hole due to overpolishing can be solved.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all transformations, equivalents, and substitutes included in the spirit and scope of the present invention. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Hereinafter, a preferred embodiment of a method of manufacturing a printed circuit board according to the present invention will be described in detail with reference to the accompanying drawings. In the following description with reference to the accompanying drawings, the same or corresponding components are given the same reference numerals. Duplicate description thereof will be omitted.

1 is a flowchart illustrating a method of manufacturing a printed circuit board according to an embodiment of the present invention, and FIGS. 2 to 6 are process diagrams illustrating a method of manufacturing a printed circuit board according to an embodiment of the present invention. 2 to 6, the build-up substrate 10, the circuit pattern 11, the pad 12, the via holes 13 and 14, and the solder resist 20 are illustrated.

First, a build-up substrate 10 having a circuit pattern 11 and via holes 13 and 14 formed in an outer layer is provided (S100). The build-up substrate 10 may be a single layer or a multilayer. The via holes 13 and 14 include not only a blind via hole 13 having one side blocked, but also a through via hole 14 having both sides open through the entire build-up substrate 10. The via holes 13 and 14 are plated with inner walls for electrical conduction between layers. However, the via holes 13 and 14 are hollow in the center, and when the solder resist 20 is applied to the surface by the empty holes, the edge portion that is the hole inlet of the via holes is used. There is a problem with this exposure.

Therefore, before applying the solder resist 20 to the surface it is necessary to plug the holes to prevent the plugging the via holes (13, 14) formed in the build-up substrate 10 with the solder resist 20 (S200) . The solder resist 20 refers to a resin material having excellent heat resistance formed on the surface of the build-up substrate 10 except the soldering portion so as not to be soldered except where necessary when soldering the build-up substrate 10.

 In particular, in the case of using the photosolder resist 20 including the photosensitive material, after applying to the build-up substrate 10 may be selectively cured through exposure and development process to remove the necessary portion.

By filling the via holes 13 and 14 with a material such as solder resist applied to the surface, it is possible to prevent the edge portion from being exposed when the solder resist 20 is applied to the surface without using expensive plugging ink.

In addition, when the plugging ink is overcharged, a front step of removing the overfilled plugging ink is required. In this embodiment, the via holes 13 and 14 are filled with the same material as the solder resist 20 applied to the surface. By omitting the front step, the number of steps can be reduced, and the problem that the plated portions of the via holes 13 and 14 are also polished and removed during the front step can also be solved. In addition, unlike a method of filling with plugging ink, a separate drying process is not required.

3 and 4, the filling of the solder resist may be filled in the via holes 13 and 14 formed on one surface thereof, and then filled in the via holes 13 and 14 formed on the other surface thereof. In the case of the through via hole 14, if the layer of the build-up substrate 10 is not filled when the layer of the build-up substrate 10 is high, the filling is alternately filled on both sides, so that the through via hole 14 having a long length of the hole can be sufficiently filled. The via holes 13 formed on both surfaces may be filled.

The solder resist 20 may be filled by the squeeze method using the screen plate making 30. 7 and 8 are cross-sectional views illustrating a method of filling a via hole using a screen plate in the method of manufacturing a printed circuit board according to an embodiment of the present invention, wherein the build-up substrate 10, the circuit pattern 11, The pads 12, via holes 13 and 14, solder resist 20 and screen engraving 30 are shown.

First, as shown in FIG. 7, the screen plate 30 is spaced apart from the build-up substrate 10. The screen plate 30 has an opening 31 formed at a portion corresponding to the positions of the via holes 13 and 14, and the size of the opening 31 is larger than that of the via holes 13 and 14, and preferably, the via hole size. It can be formed larger than about 350 ~ 400㎛.

8 is a view illustrating a step of filling solder paste into a via hole with a squeegee 35. The solder paste is pushed into the via holes 13 and 14 through an opening 31 of the screen plate 30. It can be charged. At this time, the amount of the solder resist 20 is important. This is determined by the squeeze speed, angle and pressure, etc., which can be obtained experimentally since it depends on the thickness of the substrate. For example, when the substrate thickness is 10 mm, an appropriate amount of solder resist 20 is filled by squeezing at an angle of 75 ° C., a speed of 150 ± 10 m / sec, and a squeeze pressure of 80 ± 5 kgf / cm 2.

Next, as shown in FIG. 5, the solder resist 20 is coated on the surface of the build-up substrate 10 (S300). Unlike the case where the hole is formed in the hole, the drying process may be added to prevent the solder resist 20 from flowing down. However, if it is completely dried, it is difficult to form the opening for soldering, so preliminary drying at a temperature of about 75 ° C to 80 ° C. This is to prevent the solder resist 20 from flowing down without being completely cured. Therefore, in order to apply the solder resist 20 to both sides, the solder resist 20 may be applied to one surface and pre-dried, and then the solder resist 20 may be applied to the other surface and preliminarily dried.

Next, as shown in FIG. 6, the solder resist 20 is selectively removed to expose the pad 12 for soldering (S400). In the case of using the photosolder resist 20 including the photosensitive material, a mask is stacked on the dried solder resist 20, and the mask is formed on a portion that is not to be cured, that is, a pad 12 for soldering. As shown in FIG. 6 through the exposure developing process, the pad 12 is exposed to the surface and then completely dried at a high temperature. The temperature and time of complete drying can be carried out by drying for about 30 minutes at a high temperature of about 150 ° C.

According to an embodiment of the present invention, by using the soldering resist 20 as a plugging material, the production cost is reduced, and the front surface is applied immediately after filling, and thus the drying process and the front surface which are the main processes applied to the filling method of plugging ink. The treatment process can be deleted, which increases productivity. Since the overfilled plugging ink does not need to be treated in front, the problem of deterioration of reliability due to the polishing of the plated portion of the hole due to overpolishing can be solved.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the appended claims. It will be understood that the invention may be varied and varied without departing from the scope of the invention.

Many embodiments other than the above-described embodiments are within the scope of the claims of the present invention.

1 is a flow chart showing a printed circuit board manufacturing method according to an embodiment of the present invention.

2 to 6 is a process chart showing a printed circuit board manufacturing method according to an embodiment of the present invention.

7 and 8 are cross-sectional views showing a method of filling a via hole using a screen plate in the method of manufacturing a printed circuit board according to an embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

10: printed circuit board

11: circuit pattern

12: pad

13, 14: via hole

20: solder resist

30: Screen engraving

35: squeegee

Claims (4)

Providing a build-up substrate having circuit patterns and via holes formed in an outer layer; Filling the via holes with solder resist; And Applying a solder resist of a material such as solder resist filled in the via hole to a surface of the build-up substrate; And Hardening the solder resist on the surface of the via hole and the build-up substrate together. The method of claim 1, The via hole includes a through via hole penetrating the build-up substrate. Filling the via hole is Filling the through via hole with solder resist in one surface direction; and And filling the through via hole with solder resist in the other surface direction. The method of claim 1, The solder resist comprises a photosensitive material, After applying the solder resist to the build-up substrate Depositing a mask on the solder resist; Exposing and developing the solder resist to selectively expose a surface of the build-up substrate. The method of claim 1, Filling the via hole is Aligning the screen plate with an opening corresponding to the via hole to the build-up substrate; And And inserting solder resist through the opening of the screen plate to fill the via hole with solder resist.

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