KR101933991B1 - Method for manufactuing a circuit board - Google Patents

Abstract

A method of manufacturing a circuit board according to an aspect of the present invention includes the steps of preparing a substrate having an insulating layer having a glass fiber therein and a conductive film attached to a surface of the insulating material; Forming a through-hole through the conductive film and the insulating layer; a desmearing step of removing foreign substances in the through-hole; and removing the glass fiber bur protruded from the through-hole with a fluorine-based solution .

Description

TECHNICAL FIELD [0001] The present invention relates to a method of manufacturing a circuit board,

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

Copper Clad Laminate (CCL) is widely used to manufacture circuit boards. In recent years, flexible copper clad laminate (FCCL) has also been widely used as demand for flexible circuit boards increases.

When a printed circuit board is manufactured using such an operation laminate, a through hole (TH) is formed in the copper clad laminate to form a multilayered circuit, and then the inner wall is plated to form a plate through hole PTH).

As a method of perforating the copper-clad laminate, a method of mechanically drilling using a drill bit or a method using a carbon dioxide gas laser is known. A method of forming a through hole in a substrate by using a laser is disclosed in Korean Patent Registration No. 1170753 by the present applicant.

One aspect of the present invention is to effectively remove a glass fabric burr generated in a through hole when a copper clad laminate having an insulating layer containing glass fiber is drilled with laser, And to provide a method of manufacturing a circuit board capable of having such a uniform shape.

According to an aspect of the present invention, there is provided a method of manufacturing a circuit board, comprising: (a) preparing a substrate having an insulating layer including glass fibers therein and a conductive film attached to a surface of the insulating layer; (B) forming a through hole through the conductive film and the insulating layer by irradiating the substrate with a laser; (c) a dispensing step of removing foreign substances in the through hole; And removing the glass fiber bur protruded from the through hole with a fluorine-based solution.

In the method of manufacturing a circuit board, the step (d) is performed after the step (c), and the fluorine component remaining on the substrate is removed by picking up the substrate after the step (d) can do.

Also, in the method of manufacturing the circuit board, the step (d) may be performed before the step (c).

In addition, the method of manufacturing the circuit board may further include removing an overhang of the conductive film formed in the step (b) by etching, and forming a plating layer on the inner wall of the through hole and a surface of the conductive film.

The method for manufacturing a circuit board according to claim 1, further comprising the step of patterning the circuit wiring on the plating layer.

According to the method of manufacturing a substrate according to an embodiment of the present invention, glass fiber burrs that may occur when the substrate is punched with a laser can be effectively removed. Therefore, it is possible to effectively remove the uneven shape inside the through hole by the glass fiber bur.

In addition, according to the method for manufacturing a substrate according to an embodiment of the present invention, the fluorine component remaining on the substrate can be effectively removed after etching the glass fiber bur using the solution containing the fluorine (F) component.

1A is a cross-sectional view schematically showing a through-hole formed in a copper-clad laminate having an insulating layer containing glass fibers.
FIG. 1B is a cross-sectional view schematically showing a plated-through laminated plate of FIG. 1 on which a through-hole is formed to form a plated through-hole.
2 is a flow chart schematically illustrating a method of manufacturing a circuit board according to an embodiment of the present invention.
FIGS. 3A to 3J are views schematically showing cross-sections of the copper-clad laminate in each step in order to explain each step of the manufacturing method of the circuit board of FIG. 2. FIG.
4 is a flowchart schematically illustrating a method of manufacturing a circuit board according to another embodiment of the present invention.
5A and 5B are views schematically showing a cross section of a copper-clad laminate in order to explain some steps of the method of manufacturing the circuit board of FIG.

In order to enhance the dimensional stability and mechanical strength of the copper-plated laminated board constituting the substrate, a method of impregnating an insulating resin into the glass fabric may be used in manufacturing the insulating layer of the copper-plated laminated board. Fig. 1 schematically shows a through-hole formed by irradiating laser to a copper-clad laminate having an insulating layer impregnated with glass fiber.

The substrate 1 shown in Fig. 1A is a copper clad laminate having an insulating layer 10 including glass fibers 12 and a copper foil attached to both surfaces of the insulating layer 10, that is, a conductive film 20 . When the through hole 30 is formed in the copper-clad laminate by laser, the overhang of the conductive film 20 on the periphery of the through hole 30 due to the difference in laser processability between the conductive film 20 and the insulating layer 10 -hang) 21 may be formed. The copper bur 23 is also formed by the copper powder scattered when the through hole 30 is pierced.

Since the resin of the insulating layer 10 of the substrate 1 and the glass fiber 12 also have different laser processability, the glass fiber may remain in the protruded state inside the through hole 30. [ That is, a glass fiber burr may be formed on the inner wall of the through hole 30.

Since the overhang 21 of the copper foil and the glass fiber bur are formed with irregular protrusions in the through hole 30, it is difficult to form a plating layer having a constant thickness, and the formation of the inner side surface of the through hole is uniform It goes crazy.

1B is a view schematically showing a plating through hole formed by using the substrate 1 of FIG. 1A. The plating through hole 31 can be formed by electroless copper plating the substrate 1 shown in FIG. 1A, and then performing electroplating on the electroless copper plating layer to grow the plating layer 40 to a predetermined thickness. At this time, a process of removing the overhang 21 and the burr 23 of the conductive film 20 may be performed prior to forming the plating layer 40. As a method of removing the overhang 21 and the bur 23 of the conductive film 20, a method disclosed in Korean Patent No. 1170753 by the present applicant can be used.

1B, the overhang of the conductive film 20 of the through-hole 31 and the denting phenomenon of the insulating layer 10 below the conductive film 20 cause the peripheral portion of the through- (41, 45) have a protruding shape. The inside of the through-hole 31 has a shape in which the center portion 43 protrudes due to the influence of the glass fiber bur. If the shape of the through-hole 31 is not uniform and uneven, the thickness of the plating layer 40 may be uneven, or the minimum diameter of the through-hole 31 may not be ensured .

In order to solve such a problem, a method of manufacturing a circuit board according to an embodiment of the present invention is intended to introduce a step of removing a glass fiber bur. In addition, a circuit board manufacturing method according to one embodiment of the present invention intends to introduce a process capable of effectively removing impurities such as fluorine that may remain on a circuit board as a process of removing a glass fiber bur is introduced.

2 is a schematic flow chart of a method of manufacturing a circuit board according to an embodiment of the present invention. Referring to FIG. 2, a method of manufacturing a circuit board according to an embodiment of the present invention includes preparing a substrate (S10), forming a blackening layer (S12), forming a through hole in the substrate with a laser A step S16 of removing a foreign substance in the through hole, a step S18 of removing a glass fiber with a fluorine-based solution to remove the foreign substance, a step S20 of removing residual fluorine by a pickling process, Removing the overhang (S22), forming a plating layer (S24), and performing circuit patterning (S26).

Step S10 of preparing a substrate is a step of preparing a substrate which is a raw material of the circuit board, that is, a copper-clad laminate or a soft copper-clad laminate. 3A, the substrate 1 of the present embodiment includes an insulating layer 10 made of an insulating resin material including glass fibers 12 therein, And a conductive film (20) attached to both sides of the layer (10). The insulating layer 10 may include a flexible material such as a polyimide resin, and the conductive film 20 may be formed of a material including copper, which generally has excellent electrical conductivity and mechanical characteristics. However, the material of the insulating layer 10 and the conductive film 20 is not limited thereto, and may be made of other materials having similar electrical and mechanical characteristics.

The step of forming the blackening layer S12 is a step of forming a blackening layer on the surface of the conductive film 20 in order to increase the light absorptivity of the conductive film 20. [ The blackening layer may be formed by a method of oxidizing the surface of the copper thin film constituting the conductive film 20. [ As the method of oxidizing the surface of the conductive film 20 to form the blackening layer, various methods such as an electrical method, a chemical method, and an electrochemical method can be used. FIG. 3B is a view schematically showing that the blackening layer 25 is formed on the substrate 1 of FIG. 3A. When the blackening layer 25 is formed on the surface of the conductive film 20 as shown in FIG. 3B, the absorbance of the blackened layer 25 is higher than that of the conductive film 20 in the non-oxidized state, 1) is greatly improved.

Step S14 of forming a through hole in the substrate with the laser is a step of forming a through hole by irradiating the surface of the substrate 1, that is, the blackening layer 25, with a carbon dioxide laser or the like. 3C is a view schematically showing a state in which a through hole is formed in the substrate 1 by a laser. Referring to FIG. 3C, resin residues formed by laser drilling can be attached to the inner wall surface of the through hole 30 and the perimeter of the through hole 30. Foreign matters 11 such as resin residues may need to be removed because they may cause plating defects in the process of forming the plating layer on the inner wall surface of the through hole 30. [ On the other hand, since the glass fiber 12 disposed inside the insulating layer 10 has a lower laser processability than the insulating layer 10, the glass fiber 12 can not be completely removed together with the insulating layer 10, And may remain in the protruded state inside the through hole 30. [ The overhang 21 of the conductive film 20 and the burr (not shown) of the conductive film can be formed due to the difference in workability between the conductive film 21 and the insulating layer 10 when forming the through- Same as.

The desmear step S16 is a step of removing the foreign matter 11, that is, the resin residue, which is attached to the periphery of the through hole 30. A potassium permanganate solution may be used as a washing solution for removing the foreign matter 11. In addition, the efficiency of the desmearing process can be further increased by carrying out ultrasonic cleaning together.

Also, in the desmear step S16, a step of removing the blackening layer 25 formed on the conductive film 20 may be performed together. When the blackening layer 25 is removed, an electrical method of supplying electricity to the conductive film 20 so that a reduction reaction occurs, a chemical method of reducing the chemical solution, or an electrochemical method may be used. FIG. 3D schematically shows a substrate subjected to a blackening layer removal and desmearing process. The foreign matter 11 and the blackening layer 25 around the through hole 30 of the substrate 1 are removed while the desmearing step S16 is performed as shown in Fig. However, the glass fiber bur 13 is not removed in the desmearing process, and therefore remains.

Step (S18) of removing the glass fiber etched with a fluorine-based solution, ammonium fluoride (NH ₄ HF ₂₎ by etching a glass fiber with a solution containing fluorine, such as a solution, burrs remaining glass fibers in the through-hole 30 ( 13). Although the glass fiber burr 13 is etched using the ammonium fluoride solution in this embodiment, other fluoric compound solutions capable of glass etching may be used. 3E is a view schematically showing a state in which glass fibers are removed by etching. As shown in FIG. 3E, the glass fiber bur protruded into the through hole 30 is removed through this step, so that the protrusion can be effectively reduced on the inner side of the through hole 30. FIG. However, the overhang 21 of the conductive film 20 and the burr (not shown) of the conductive film may still remain.

On the other hand, even if the step S18 of removing the glass fiber 12 by etching is completed, the fluorine component still remains on the surface of the substrate. 3F shows exaggerated fluorine remaining on the surface of the substrate. As shown in FIG. 3F, the fluorine ions F can remain on the surface of the conductive film 20 or the inner wall surface of the through hole 30 have. Since fluorine is an element having high reactivity, when fluorine is left on the substrate, there is a high possibility that the fluorine reacts with a substance such as a plating layer to be formed later, thereby causing defects in the circuit board. Therefore, after the glass fiber etching, the fluorine remaining on the substrate must be removed.

In the step S20 of removing residual fluorine through the pickling process, the substrate is cleaned using an acidic solution, that is, soft etching is performed to remove fluorine components remaining on the substrate. This step may further include a plurality of washing steps. In general, as a method for removing fluorine, there is known a method of neutralizing by using a basic solution, for example, a sodium hydroxide solution. According to the experiment of the present application, it has been confirmed that a method using a pickling method is more effective in removing fluorine Respectively. On the contrary, Applicant observes that the fluorine mainly remains on the surface of the conductive film 20 because the surface of the conductive film 20 is partially etched by the pickling treatment and the fluorine is removed together.

3G schematically shows a cross section of the substrate after the pickling process. Referring to FIG. 3G, the thickness d2 of the conductive film 20 due to the acid pickling is smaller than the thickness d2 of the conductive film 20 before the pickling process (D1) of the film 20, as shown in FIG. Since the surface of the conductive film 20 is removed by etching and the fluorine (F) component remaining on the surface of the conductive film 20 is also removed, the fluorine remaining on the substrate can be effectively removed.

The step of removing the overhang of the conductive film (S22) is a step of removing the overhang and the burr remaining in the conductive film, and a soft etching method may be used. 3H schematically shows spraying of the etching solution to the periphery of the through hole 30 by using a slit nozzle (N). As shown in FIG. 3H, when the nicking liquid is injected into the through-hole 30, the overhang 21 of the conductive film on the through-hole surface can be effectively removed by the flow of the nicking liquid. In order to remove the overhang 21, a flood bar disposed above and below the substrate may be used. A specific method of using the slit nozzle or the flood bar to remove the overhang of the conductive film is disclosed in the registered patent No. 1170753 of the present applicant, and a description thereof will be omitted.

The step of removing residual fluorine (S20) through the pickling process and the step (S22) of removing the overhang (21) of the conductive film may be performed simultaneously as a single process.

The step of forming the plating layer (S24) is a step of plating the substrate on which the residual fluorine and the overhangs 21 of the conductive film have been removed by the pickling process to form a metal plating layer on the surface of the substrate including the inner wall surface of the through hole (30). As the metal to be plated on the substrate, the same material as the conductive film, that is, copper may be used. 3I schematically shows a state in which a plating layer 40 is formed on a substrate. As shown in FIG. 3I, the plating through holes 31 are formed by plating, so that the upper and lower surfaces of the substrate are electrically connected to each other. In the step of forming the plating layer (S24), a plating layer is formed on the inner wall surface of the through hole 30 and the surface of the substrate by electroless plating, and the plating layer is further grown by electroplating with a seed layer Can be adopted.

The step S26 of patterning the circuit is a step of fabricating the circuit board by forming a circuit on the upper and lower surfaces of the conductive film 20 of the substrate. The process of patterning the circuit may be performed using dry film resist (dry film resist) and lithography. Since the circuit patterning process is well known to those of ordinary skill in the art, a detailed description thereof will be omitted. 3J schematically shows a state in which circuits are patterned on both sides of the substrate. As shown in FIG. 3J, the circuit patterns 51 formed on the upper and lower surfaces of the substrate are electrically connected to each other by the plating through holes 31.

As described above, according to the method of manufacturing a circuit board of this embodiment, the inner wall surface of the through-hole can be formed in a uniform shape by effectively removing burrs by the glass fiber. Therefore, the thickness of the plating layer can be uniformly formed over the entire inner wall surface of the through hole, and the diameter of the through hole can be effectively secured.

Further, according to the method for producing a circuit board of this embodiment, even if the glass fiber bur is removed by using the fluorine-based compound solution, the fluorine ions that can remain on the substrate can be effectively removed. Therefore, it is possible to effectively prevent defects of the substrate due to fluorine remaining on the substrate.

Next, a method of manufacturing a circuit board according to another embodiment of the present invention will be described with reference to the drawings.

4 is a flowchart schematically illustrating a method of manufacturing a circuit board according to another embodiment of the present invention. Referring to FIG. 4, a method of manufacturing a circuit board according to an embodiment of the present invention includes preparing a substrate S30, forming a blackening layer S32, forming a through hole in the substrate with a laser S34, (S38) of removing the overflow of the conductive film, a step of forming a plating layer (S42), a step of patterning the circuit Step S44.

A step S30 of forming a substrate of the present embodiment, a step S32 of forming a photometry layer, a step of forming a through hole in the substrate with a laser, a step S40 of removing an overhang of the conductive film, A step S44 of patterning the circuit, a step S10 of preparing a substrate of the circuit board manufacturing method of Fig. 2, a step of forming a blackening layer S12, a step of forming a through- A step S24 of removing the overhang of the conductive film, a step S24 of forming the plating layer, and a step S26 of patterning the circuit are omitted. Therefore, a duplicate description thereof will be omitted.

However, the method of manufacturing the circuit board of this embodiment differs from the method of manufacturing the circuit board of FIG. 2 in that the step S36 of etching the glass fiber bur with the fluorine-based solution prior to the step S38 of removing and blackening the blackening layer, .

5A is a view schematically showing the state of the substrate in the step (S36) of etching the glass fiber bur with the fluorine-based compound solution. Referring to FIG. 5A, when the fluorine-based compound solution is applied to the through-hole 30 of the substrate, the glass fiber burr 13 protruding into the through-hole is removed. On the other hand, since the fluorine-based compound is used in the step of etching the glass fiber burls 13, the fluorine ions F remain on the surface of the substrate as in the above-described embodiment.

On the other hand, in the method of manufacturing the circuit board of the embodiment of Fig. 2, the pickling process is performed to remove the fluorine ions (F). In the method of manufacturing the circuit board of this embodiment, after the glass fiber burr 13 is removed by the fluorine- The desmear step S38 can be performed without a separate pickling process. The desmear step S38 of this embodiment may be performed in substantially the same manner as the desmear step S16 of the embodiment of FIG. 2, and may be performed together with the blackening layer removing step.

The present applicant has confirmed through experiments that fluorine ions are effectively removed even if a glass fiber is etched with a fluorine-based compound solution and then subjected to a desmearing process without a pickling process. This fluorine ion removal effect is attributed to the fact that the neutralization reaction is caused between the dismear solution and the remaining fluorine-based compound leaving a basicity, and the fluorine ions remaining on the surface of the blackening layer are removed together with the removal of the blackening layer . Also, in the desmear stage, ultrasonic cleaning can also be performed. It is understood that such an ultrasonic cleaning process is also effective in removing fluorine components remaining on the surface of the substrate.

5B is a schematic view of a substrate subjected to a blackening layer removal and desmearing process after the glass fiber bur 13 has been removed by etching. As shown in FIG. 5B, it can be seen that the fluorine ions F are effectively removed even after the glass fiber burr 13 is removed by etching and thereafter no additional pickling process is performed.

As described above, in the method of manufacturing a circuit board of this embodiment, since a separate pickling process is not performed to remove the fluorine ions F, etching of the conductive film can be effectively reduced. That is, according to the circuit board manufacturing method of the present embodiment, the decrease in the thickness d1 of the conductive film due to the etching can be greatly reduced.

In the case of the circuit board, since the thickness of the conductive layer in which the circuit is formed must be ensured to be a predetermined amount or more, if the thickness of the conductive film 20 is reduced, the plating layer 40 should be formed thicker. On the other hand, according to the circuit board manufacturing method of the present embodiment, the thickness of the conductive film 20 can be effectively maintained, and the thickness of the plating layer 40 formed thereon does not need to be greatly increased. Therefore, the plating material and time required for forming the plating layer 40 can be effectively reduced by the manufacturing method of the circuit board of this embodiment.

In addition, when the pickling process for removing fluorine ions (F) is omitted as in the present embodiment, the entire process is simplified, and the time and cost required for manufacturing the circuit board may be effectively reduced.

In the present embodiment, it is described that the step S36 for etching the glass fiber burls 13 and the step S38 for removing the blackening layer are not performed separately, but the step of etching the glass fiber burr A pickling process may be added between the blackening layer removing step and the desizing step S38. However, even in such a case, the strength of the pickling process can be lowered compared to the method of etching the glass fiber bur (S18) after the desizing step S16 as in the embodiment of Fig. This is because it is not necessary to increase the strength of the pickling process because the fluorine ions will be removed anyway in the subsequent desmear step S38. That is, even if a separate pickling step is added between the step S36 of etching the glass fiber bur and the step S38, the etching amount of the conductive film 20 can be maintained at a relatively small level.

As described above, the circuit board manufacturing method of the present embodiment can omit or simplify the pickling process for residual fluorine removal, thereby reducing the thickness of the conductive film 20 and simplifying the overall process. Time and cost can be effectively reduced.

Also, the circuit board manufacturing method of the present embodiment is similar to the circuit board manufacturing method of Fig. 2, in that the uniformity of the plating layer and the uniformity of the shape of the through hole 31 due to the effective removal of the glass fiber burr 13 in the through hole 30 Of course, can be obtained.

Although some embodiments of the present invention have been described above, the present invention is not limited thereto, and may be embodied in various forms within the scope of the technical idea of the present invention.

1 ... substrate
10 ... insulating layer
12 ... glass fiber
20 ... conductive film
25 ... blackening layer
30 ... through hole
31 ... plating through hole
40 ... plated layer

Claims (5)

(a) preparing a substrate having an insulating layer having a glass fiber therein and a conductive film attached to a surface of the insulating layer;
(b) irradiating the substrate with a laser to form a through hole through the conductive film and the insulating layer;
(c) a desmear step of removing foreign matter in the through-hole;
(d) removing the glass fiber bur protruded through the through-hole with a fluorine-based solution; And
(e) etching the substrate from which the glass fiber bur is removed by using an acidic solution to remove fluorine components remaining on the substrate. delete The method according to claim 1,
Wherein the step (d) is performed before the step (c). 4. The method according to any one of claims 1 to 3,
Removing an overhang of the conductive film formed in the step (b) by etching; And
Forming a plating layer on the inner wall of the through hole and on the surface of the conductive film,
And removing the overhang by etching is performed simultaneously with the step (e). 5. The method of claim 4,
And patterning the circuit wiring on the plating layer.

Images