KR20080027056A - Manufacturing method for micro circuit of pcb - Google Patents

Abstract

A manufacturing method for a micro circuit of a PCB(Printed Circuit Board) is provided to mount a landless circuit and a chip required in a fine pattern, reduce a plating area, and improve a plating thickness deviation by filling a via hole with the plating, thereby forming the micro circuit. A manufacturing method for a micro circuit of a PCB includes the steps of: coupling by stacking a surface insulating layer(3) and a copper foil(4); processing a through hole; processing a laser hole; performing electroless copper plating(7); forming a pattern on a substrate surface with a dry film as a photosensitive material in a photo image method to form a circuit after the electroless copper plating; performing electrolytic copper plating(2) on the substrate imaged by the dry film; plating only an open region without the dry film not to plate a region where the dry film is closely adhered; performing electrolytic nickel plating(11) and electroless nickel plating when the electrolytic copper plating is completed; coating solder resist ink(12) on the substrate with a circuit; and completing the PCB by performing electroless gold plating(13).

Description

Manufacturing method for printed circuit boards {Manufacturing Method for Micro Circuit of PCB}

1a to 1j show a manufacturing process of a conventional printed circuit board,

Figure 1a is a schematic enlarged cross-sectional view showing a state in which the copper foil laminated on the insulating layer in the process of forming a conventional new layer

Figure 1b is a schematic enlarged cross-sectional view showing a state in which through holes and laser holes are processed for the conventional electrical interlayer coupling

Figure 1c is a schematic enlarged cross-sectional view showing a state of electroless copper plating so that electricity flows through a conventional insulating layer.

1D is a schematic enlarged cross-sectional view showing a state in which a copper plating is performed on a surface of a substrate and a hole in a conventional substrate

1E is a schematic enlarged cross-sectional view showing that the circuit forming portion is protected by a conventional dry film.

1F is a schematic enlarged cross-sectional view showing a state in which a copper foil is removed by etching a copper foil portion unnecessary for conventional circuit formation with a chemical agent;

Figure 1g is a schematic enlarged cross-sectional view showing a state in which the conventional dry film peeled off with a chemical

Figure 1h is a schematic enlarged cross-sectional view showing the application of the circuit portion in the solder resist ink to protect the conventional printed circuit board

1I is a schematic enlarged cross-sectional view showing electroless nickel plating on a conventional exposed copper foil surface.

Figure 1j is a schematic enlarged cross-sectional view showing a printed circuit board manufactured by electroless gold plating on a conventional electroless nickel plating.

2a to 2n of Figure 2 shows a manufacturing process for forming a microcircuit of the present invention

  2a is a schematic enlarged cross-sectional view showing a state in which the insulating layer and the copper foil of the present invention are laminated and bonded.

Figure 2b is a schematic enlarged cross-sectional view showing a state of processing the through-hole and laser hole of the present invention

Figure 2c is a schematic enlarged cross-sectional view showing the step of performing an electroless chemical copper on the surface of the substrate of the present invention

Figure 2d is a schematic enlarged cross-sectional view showing that the plating is not performed by masking the unnecessary portion in the circuit formation with a dry film for the circuit formation of the present invention.

Figure 2e is a schematic enlarged cross-sectional view showing that only the portions required for circuit formation by electroplating the plating on the portion where the dry film of the present invention is not masked.

Figure 2f is a schematic enlarged cross-sectional view showing that the electroplated nickel plated surface of the present invention

2I is a schematic enlarged cross-sectional view showing a state in which a dry film masking the copper foil of the present invention is removed.

Figure 2j is a schematic enlarged cross-sectional view showing a state in which a circuit is formed by etching a copper foil that is not electrically nickel plated with the chemical of the present invention.

2K is a schematic enlarged cross-sectional view showing a state where the solder resist ink of the present invention is applied.

Figure 2L is a schematic enlarged cross-sectional view showing electroless gold plating on the surface of the electronickel plating of the present invention.

         ** Explanation of symbols for the main parts of the drawings **

1. Surface Circuit 2. Copper Plating 3. Insulation Layer

4. Copper foil 5. Through hole 6. Laser hole

7. Electroless Copper Plating 8. Dry Film 9. Open Area

10. Via hole 11. Electro nickel plating 12. Solder resist ink

13. Electroless Gold Plating

The present invention relates to a method for manufacturing a printed circuit board, and fills a laser hole for interlayer bonding when forming a microcircuit with a plating, thereby making a fill via hole. The purpose is to be able to manufacture by using the equipment to make the microcircuit more compact.

In the conventional substrate manufacturing method, the substrate was manufactured by electroplating the entire substrate and removing copper foil in the remaining portion except the circuit for circuit formation.

However, since the above method is a method of plating copper foil on the entire surface of the substrate and removing other parts than the circuit pattern, the manufacturing cost is high, and the working time is long, and thus there is a technical limitation on the formation of the microcircuit.

 In more detail, it is as follows.

1 illustrates a process of manufacturing a printed circuit board by a conventional method, and a detailed manufacturing method is as follows.

The new insulating layer 21 is laminated on the existing insulating layer 21 ′, bonded thereto, and the through-hole 22 and the laser drill 23 are laser drilled through a CNC drill for interlayer electrical conduction. Process.

The side of the hole is made of an electrically insulative layer, and electroless chemical copper plating (24) is carried out so that electricity flows. The plating thickness is generally thinly made within 0.5 μm, and the electroplating (25) is made in the state of electricity. Proceeding to form a plating layer in 10 ~ 30㎛.

The surface of the insulating layer 25 'inside the hole has a plating thickness of 10 to 30 µm, but the thickness of the substrate surface is increased to a thickness of 25 to 45 µm since the plating layer rises on the copper foil 26 having a thickness of 15 µm. It is a serious obstacle to the formation of microcircuits.

In the panel plating method for plating the entire surface, the smaller the thickness variation is, the more advantageous for the formation of the microcircuit. However, in the conventional electroplating panel electroplating (25), there is a technical limitation in reducing the thickness variation. There was a limit to making.

In addition, the inside of the laser hole 23 connecting the different insulating layers 27 has a disadvantage in that the plating thickness is not good due to the poor flow of the plating chemical or the plating is broken, which causes serious voids in reliability due to void defects. There is a problem that, as a problem, after the electroplating (25) in the image process in close contact with the photosensitive dry film 28, the circuit is formed, and the development process to remove the unnecessary parts, there is a disadvantage that goes through The dry film 28 masks the portion of the laser hole upper portion 28 'and the circuit forming portion 28 " like 1e, thereby spraying the etching liquid on the remaining portion to peel off the remaining copper foil to form a circuit of the substrate. will be.

That is, when the etching liquid is sprayed to remove the unnecessary copper foil 25 ", the exposed copper foil except for the portion masked with the dry films 28, 28 ', 28 " is corroded and removed. Copper plating (25) has a lot of problems in setting the etching conditions due to the uneven surface thickness due to the plating variation for each part, and inadvertent short circuit due to excessive etching or broken short circuit due to unetching There could be a lot of problems in setting the condition.

In addition, the conventional method has a thickness of 25 ~ 40㎛ thick to etch the copper foil (25 ") to increase the resistance of the circuit becomes narrow during the etching, resulting in an unstable electrical signal, interlayer There is a problem with the reliability of disconnecting electrical connections.

After the circuit is formed by etching, the solder resist ink 29 is applied by screen printing to the remaining portions except for the parts to be mounted after removing the dry film 28.

Where the solder resist ink 29 is not applied, the copper foil surface 31 is plated with the electroless nickel plating 30, and the electroless gold plating 32 is continuously performed in-line immediately to manufacture a printed circuit board. will be.

As described above, the conventional substrate manufacturing method has a high manufacturing cost by electroplating the entire substrate 25 and removing copper foil to form a circuit again, and there is a technical limitation on forming a fine circuit.

Therefore, an object of the present invention is to make a microcircuit to compensate for the conventional problems as described above and to properly cope with products that are becoming more advanced, and to form a landless circuit by filling a laser hole with plating. It was invented to be suitable for precision miniaturized products by, and is a method of manufacturing high-end printed circuit boards while reducing the manufacturing cost due to unnecessary plating.

The present invention is particularly difficult to fill the laser hole plating during the electroplating process in the plated plating is technically difficult, but in the present invention, only the necessary part is plated with a dry film to be plated to overcome the technical limitations enough to print Mass production of circuit boards is possible.

In addition, since the present invention proceeds with the electro-nickel plating before removing the dry film, as shown in Figure 2f, only the necessary portion can be nickel plated, in Figure 2j the electrical nickel plating layer is complete when etching the copper foil for circuit formation It can be easily etched because the thickness of the copper foil to be closely adhered to protect and etch the circuit is less than 15㎛, and it is difficult to form the fine circuit by uniform etching since the copper foil and the electroplating layer should be etched together in FIG. However, the present invention is to solve the conventional problems and to be suitable as a manufacturing method of a miniaturized and advanced printed circuit board as follows, the present invention will be described in detail by the accompanying drawings.

In the step of bonding the surface insulating layer by laminating copper foil and performing electroless copper plating after through hole and laser hole processing,

Bonding the surface insulating layer to the copper foil by lamination:

Step through the through holes:

Steps to process laser holes:

Steps to proceed with electroless copper plating:

After the electroless copper plating to form a circuit by using a photosensitive dry film of the photosensitive material to form a pattern on the surface of the substrate by a photo image method:

Steps to electroplate the substrate imaged with dry film:

Where the dry film is in close contact with the plating, only the open areas without dry film are plated.

When the electroplating is completed, proceed with electro nickel plating:

Applying the solder resist ink to the circuit formed substrate:

The process consists of electroless gold plating to complete the printed circuit board.

Referring to the method of the present invention as described above in detail as follows.

In the present invention, the method for manufacturing a printed circuit board for forming a microcircuit is electroplated (2) only in a portion required to form the surface circuit 1 in FIG. 2, and thus, the invention has been invented to enable a fine pattern microcircuit. As follows.

The process of bonding the surface insulating layer 3 to the copper foil 4 in a stack and processing the through hole 5 and the laser hole 6 and then performing the electroless copper plating 7 is the same as in the conventional manufacturing method. In the method of manufacturing a substrate, the panel plating is performed, but in the present invention, a pattern is formed on the surface of the substrate using a dry film 8 of photosensitive material to form a circuit after the electroless copper plating 7.

When electro-plating (2) the substrate imaged with the dry film (8), the portion where the dry film (8) is in close contact is not plated, and only the open portion (9) without the dry film (8) is raised. do.

At this time, since unnecessary parts are not plated, the area for removing copper foil in post process etching is reduced, and in particular, the via hole 10 can be filled with plating, thereby enabling landless circuits and chip mounting necessary for fine patterns, and plating. It is a printed circuit board manufacturing method that enables the formation of fine circuits by reducing the area and improving the variation in plating thickness.

When the electroplating (2) is completed, the electro-nickel plating (11) is carried out, in the conventional electroless nickel plating process, the plating temperature is at a high temperature of 80 ℃ or more, the electro-nickel plating (11) even at 50 ℃ or less It is possible to electroplated nickel (11) of high quality while easy plating operation.

The nickel layer protects the microcircuits and thus prevents damage to the circuits that may occur in the handling of the substrate, and improves the defect that the surface is oxidized by gas than when the surface is exposed to copper. .

The dry film 8 masked for selective plating in FIG. 2F is removed with sodium hydroxide or potassium hydroxide chemicals, and the exposed portions of the surface copper foil 7 are corroded in the etching process to form only necessary circuits.

At this time, the necessary circuit part is protected by the nickel layer, and only the unnecessary part is etched, but only the surface 15 μm of the copper foil 7 needs to be removed.

After applying the solder resist ink 12 to the substrate on which the circuit is formed in the above state, the electroless gold plating 13 is further performed to complete the printed circuit board.

As described above, in the present invention, the process of combining the surface insulating layer by laminating the copper foil and performing electroless copper plating after the through hole and the laser hole processing is the same as in the conventional manufacturing method. In the present invention, to form a circuit after electroless copper plating to form a pattern on the surface of the substrate by a photo-image method with a dry film of a photosensitive material, the area where the dry film is in close contact when the copper film is subjected to the electro-plated substrate Plating will be raised only in the open area without plating and without dry film. At this time, the unnecessary part is not plated, so the area for removing copper foil in post-process etching is reduced. Landless circuit and chip can be mounted and plating area can be reduced The thickness variation is useful to improve the inventions capable of forming fine circuits.

Although the present invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that various modifications and changes are possible within the technical spirit of the present invention, and that such modifications and modifications do not change the appended claims. will be.

Claims (6)

Bonding the surface insulating layer to the copper foil by lamination: Step through the through holes: Steps to process laser holes: Steps to proceed with electroless copper plating: After the electroless copper plating to form a circuit by using a photosensitive dry film of the photosensitive material to form a pattern on the surface of the substrate by a photo image method: Steps to electroplate the substrate imaged with dry film: Where the dry film is in close contact with the plating, only the open areas without dry film are plated. When the electroplating is completed, electro-nickel plating and electroless nickel plating are performed. Applying the solder resist ink to the circuit formed substrate: Method of manufacturing a fine circuit of a printed circuit board comprising the step of completing the printed circuit board by electroless gold plating The method of manufacturing a microcircuit for a printed circuit board according to claim 1, wherein a pattern is formed on the electroless copper plating with a dry film in order to plate only necessary portions. The method of manufacturing a microcircuit of a printed circuit board according to claim 1, wherein a pattern is formed of a dry film, and electroplating is performed to form a via hole by filling the laser hole with plating in the step and the electroplating. The method of manufacturing a microcircuit of a printed circuit board according to claim 1, wherein the circuit is protected by electroplating nickel or electroless nickel after the electroplating. The method of manufacturing a fine circuit of a printed circuit board according to claim 1, wherein the nickel plating layer protects the circuit in an etching process for forming a circuit. The method of claim 1, wherein the solder resist ink is printed on the nickel plating layer.

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