KR100327705B1 - Method of producing a multi-layer printed-circuit board - Google Patents

Abstract

Disclosed is a method of manufacturing a build-up multilayer printed circuit board that can be used in an information device such as a notebook PC, an HDD, or a small communication device such as a mobile phone, a digital video camera, or the like. According to the present invention, a chemical copper or conductive material is attached to the entire surface of the insulating substrate on which the circuit is formed, and a photosensitive resin is applied thereon, and only the conductive hole is electroplated to form a conductive vertical circuit, and printed or coated on both sides with insulating resin. After treatment, complete ultraviolet irradiation or heat curing treatment is followed by sanding polishing to form and expose lands of the conductive circuits, followed by electroplating of roughness forming, chemical copper, and electrophoresis. Therefore, the reliability of the through-holes is improved, and the area of the existing through-holes can be utilized, so that the density and size can be reduced. In addition, the entire manufacturing process of the multilayer printed circuit board is shortened, and the component can be mounted on the blind via hole portion on the surface layer circuit, thereby increasing the mounting density of the component.

Description

Method for producing a build-up multilayer printed circuit board

The present invention relates to the manufacture of a multilayer printed circuit board, and more particularly, it is possible to miniaturize by utilizing the area of an existing via hole, which can be applied to a high density circuit, and a build-up multilayer printed circuit board having improved reliability for the via hole. It relates to a manufacturing method of.

In general, a printed circuit board is wired to one side or both sides of a board made of various thermosetting synthetic resins, and then the ICs or electronic components are disposed and fixed on the boards, and electrical wiring therebetween is coated with an insulator.

Since the development of electronic components, multilayer printed circuit boards made of overlapping circuit conductors have been developed, and recently, researches on the high density of multilayer printed circuit boards have been actively conducted, and among them, build-up multilayer printed circuit boards have been actively studied. Has been developed and widely used.

In the method of manufacturing a build-up multilayer printed circuit board according to the prior art, a multilayer circuit is formed by sequentially stacking an insulating layer and a circuit conductor by using photosensitive insulating resin instead of epoxy glass or prepreg. How to form. The multi-layer printed circuit board by the build-up can not only form via holes connecting the interlayer circuits and via holes of very small diameters, but also have a thin circuit thickness, so that fine circuits can be easily formed to form high-density circuits. In the case of epoxy glass, which is a conventional insulating layer, a minimum thickness of 0.1 mm is used. However, in the build-up multilayer printed circuit board, a thickness of 0.05 mm may be formed, thereby making it thin.

2 is a diagram schematically illustrating a manufacturing process of a build-up multilayer printed circuit board according to the prior art.

Referring to FIG. 2, first, the photosensitive insulating resin or the epoxy thermosetting resin is cut to a certain size, and then the inner layer circuit is formed by performing an etching process with the photosensitive film attached on both surfaces thereof (step SS1).

Next, after the substrate on which the inner layer circuit is formed is subjected to a pretreatment or surface polishing process, the insulating resin layer on which the wiring pattern of the circuit part is printed is applied on both sides of the substrate over the first and second stages (step SS2). At this time, the insulating resin layer is first applied to one surface of the substrate, and then the insulating resin layer is applied to the other surface of the substrate.

Thereafter, the insulating plate on which the insulating resin layer is applied is preliminarily dried, and then the photosensitive film is attached to form a conductive line and a conductive via hole to which the circuit is connected through ultraviolet exposure and development (step SS3). On the other hand, when the epoxy thermosetting resin is used, the preliminary drying, the exposure and the development process may be omitted, and the conductor line and the conductive via hole may be formed by using a laser using a computer numerical control (CNC) method. The insulating plate on which the conductive via hole is formed is completely dried for later processing and then subjected to surface polishing.

However, scum may remain in the conductive via hole in the insulating plate after the conductive via hole is completely dried and subjected to surface polishing, thereby reducing the reliability of the via hole. Therefore, the soft etchant is used to remove smear remaining in the through via hole. Thereafter, electroless chemical copper is deposited on the entire surface to impart conductivity to the substrate (SS4).

After the completion of the chemical copper plating, in order to reinforce the plated via hole and to reinforce the circuit pattern, electrolytic plating is performed on the surface of the copper plated on the surface of the insulator at a predetermined thickness (SS5).

After the electroplating is completed, an insulating coating film is formed in addition to the plating layer necessary for preventing oxidation of the copper wiring and short circuit of the copper wiring, that is, the part on which the component is mounted, and etching is performed to copper plating the outside of the insulating coating film. Is removed to form a circuit (SS6).

Next, as in the step (SS2), after performing the pre-treatment or surface polishing process of the substrate on which the circuit is formed, the insulating resin layer is applied to prevent the via hole (SS7). Thereafter, a conductive via hole and a conductor line to which a circuit is connected are formed in the same manner as described in the step SS3 (step SS8).

Then, through the same process as in steps SS4 to SS8, the printed circuit boards on which the respective wiring patterns are formed are laminated to each other, and the multi-layer printing is performed through the plating step of plating the inner walls of the via holes of the stacked multilayer printed circuit boards. A circuit board is manufactured (step SS9). At this time, in the outermost layer, a plugging process is performed using a separate resin in a blind conductive via hole in which the component is mounted.

However, in the conventional build-up multilayer printed circuit board manufacturing process as described above, the use of the photosensitive resin based on the insulating layer material, the electrical properties and physical properties are lower than that of the thermosetting resin, and when using the epoxy thermosetting resin, enormous facility investment and two times Hole processing using a laser is required, and there is a problem of reliability of conduction between conductors due to resin scum at the processing site. In addition, due to the nonuniformity of the current density distribution due to the micro via hole during electroplating, the throwing power is low and the reliability is lowered, and there is a problem that the hole blocking operation and the leveling operation are required in the integration of the circuit. The term used is used in the following meanings: Sanding Polishing: The use of sandpaper to cut the surface evenly to the desired thickness. Roughness formation increases the surface area by chemically or mechanically processing irregularities on the surface. To improve adhesion, and blind via-holes refer to holes that do not penetrate the substrate but only a portion of the conductor layer, and via holes represent electrical through holes. In addition, prepreg means that the glass and the fiber are coated with a thermosetting resin and semi-cured. The pretreatment is about 0.5 to 1.5 μm on the surface of the conductor circuit (inner layer circuit) formed on the substrate before the insulating resin is applied to the substrate. It means the process of strengthening the adhesive strength with insulating resin by processing irregularities and cleaning other foreign substances. In addition, plugging refers to a process of filling a processed hole with an insulating resin, a conductive paste, and a conductor, and a throwing power is applied to the substrate surface and the substrate when copper plating is applied to the processed substrate. It means that the plating thickness with the hole wall surface is expressed as a ratio. Desmear refers to a process of cutting the surface of the insulating resin by about 1 μm (using KMnO ₄ ) and removing debris to improve adhesion to the insulating resin during chemical copper plating. By removing the moisture and volatile components generated during processing and eliminating the stress applied to the substrate, it indicates that the substrate is stored at a constant temperature for a certain time in order to minimize the influence of the stress generated in the subsequent process.

The present invention has been made to solve the conventional problems as described above, the object of the present invention is to manufacture a build-up multi-layer printed circuit board capable of increasing the density and miniaturization, improve the reliability of the circuit and increase the mounting density of the components To provide a method.

1 is a diagram schematically illustrating a manufacturing process of a build-up multilayer printed circuit board according to the present invention;

2 is a diagram schematically illustrating a manufacturing process of a build-up multilayer printed circuit board according to the prior art.

In order to achieve the above object, the present invention,

After cutting the copper clad laminate to a certain size, by applying a photosensitive emulsion and performing an etching process to form an inner layer circuit (S1);

Stacking a conductive material on both surfaces of the substrate on which the inner layer circuit is formed (S2);

Attaching a photosensitive resin on the substrate on which the conductive material is laminated to form a via hole pad part and a dummy pattern, and then performing electroplating on the exposed via hole pad part and the dummy pattern part (S3);

Peeling the photosensitive resin to remove the conductive material, and then performing pretreatment or roughness treatment to improve adhesion to the insulating resin (S4);

Forming an insulating layer on the pretreated or roughened substrate (S5);

Polishing the insulating layer (S6);

Forming a conductive land for the via hole on the polished substrate (S7); And

It provides a method of manufacturing a multilayer printed circuit board comprising the step (S8) to form a build-up multilayer printed circuit board by repeatedly performing the step (S1) to the step (S7).

As described above, in the method for manufacturing a build-up multilayer printed circuit board according to the present invention, a chemical copper or conductive material is attached to the entire surface of an insulating substrate on which a circuit is formed, and a photosensitive resin is applied thereon, and only a conductive hole and a dummy pattern are provided. Electroplating is used to form a vertical conducting circuit. After printing or coating on both sides with insulating resin, the surface of the conducting circuit is exposed by sanding and polishing after complete UV irradiation or heat curing. Electrode plated.

Hereinafter, a method of manufacturing a build-up multilayer printed circuit board according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating a manufacturing process of a build-up multilayer printed circuit board according to the present invention.

Referring to FIG. 1, first, a copper coating laminate is cut to a predetermined size using a specially manufactured cutting machine, and then a photosensitive emulsion is applied on a thin core to a thickness of about 5 to 10 μm and then etched. To form an inner layer circuit (step S1).

Next, a conductive material is laminated on both surfaces of the substrate on which the inner layer circuit is formed. In other words, electroless chemical copper is deposited to a thickness of about 0.5 to 3 탆. Thereafter, by attaching the photosensitive film to a thickness of about 40 μm and dissolving and developing only the unexposed portion by using a solution of Na ₂ CO ₃ of about 0.75 to 1.2% in a state in which only the conductive via hole portion and the dummy pattern were blocked with ultraviolet rays. A via hole having a diameter of ˜150 μm is formed, and the inner copper circuit layer is exposed, so that conductivity is imparted to the entire surface of the substrate on which the pattern is exposed (step S2).

Next, electrolytic plating is applied to the exposed via hole and the pad portion at a thickness of about 30 to 120 탆 (step S3).

Thereafter, about 3 to 5% of NaOH or KOH is used to remove the photosensitive resin, and a soft corrosion solution is used to remove the chemical copper layer, while pretreating the copper circuit layer to enhance adhesion with the insulating layer. Or roughness processing. As a result, the copper circuit layer has a roughness of about 0.5 to 1.5 mu m (step S4).

Next, in order to protect the via-hole plating layer, a thermosetting epoxy resin is laminated on one or both sides of the insulating substrate with a thickness of about 30 to 110 μm using an applicator and a printing machine over the first to third steps to form an insulating layer (step S5).

After drying the insulating substrate on which the insulating layer is laminated in a hot air dryer, sanding of the insulating layer is performed in order to secure the thickness necessary for insulation, maintain the flatness against the thickness of the insulating layer, and to expose the circuit of the conductive portion. The polishing process is performed (step S6).

The surface of the polished insulating resin is desmeared to give roughness on the surface to improve the bonding strength of the chemical copper, and then the chemical copper plating is performed on the entire surface at a thickness of about 2 to 3 μm or about 0.3 to 0.5 μm. After the aging treatment is performed at about 80 to 110 ° C. for 30 to 50 minutes, the stress between the insulating resin layer and the chemical copper layer is solved, thereby improving reliability. Pattern or panel electrocopper plating is performed here to form a conductive circuit for the via hole (step S7).

Again, as in the step S1, a photosensitive emulsion is applied and an etching process is performed to form a circuit, and subsequent steps are repeatedly performed to form a buildup multilayer printed circuit board (step S8).

As a result, the formation of an intermediate conduction circuit by plating, and the plugging process for the hole, improve the reliability (maintain flatness) and the automatic hole plugging effect for the laser hole processing machine and the plugging process. You can get it.

In addition, although the plating resist process of the conductive material and the conductive via hole part is required, the resist coating (4 to 6 times), two laser processing, unstable desmearing process, hole plugging process, and the like are repeated compared to the conventional multilayer printed circuit board manufacturing process. Comparing the sand polishing process, it can be competitive in terms of manufacturing cost.

As mentioned above, in the method of manufacturing a multilayer printed circuit board according to the present invention, by using a build-up method of sequentially stacking a resin insulating layer and a circuit conductor layer, interlayer conduction is performed when forming a conventional multilayer printed circuit board. After the epoxy resin was applied to form the hole, a through hole processing step using a laser was excluded. In addition, by plugging copper into copper via the conductive via hole plating method for the inner layer and the surface layer, the circuit density of the circuit can be improved, and the component can be mounted on the blind via hole portion on the surface layer circuit, thereby making the thin and thin end of the build-up multilayer substrate component. Reliability can be secured for fire extinguishing and through holes. Therefore, the preliminary process of the multilayer printed circuit board is shortened, reliability is improved, and small capital participation can be obtained, thereby securing the competitiveness of SMEs.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the present invention without departing from the spirit and scope of the invention described in the claims below. I can understand that you can.

Claims (4)

After cutting the copper clad laminate to a certain size, by applying a photosensitive emulsion and performing an etching process to form an inner layer circuit (S1); Stacking a conductive material on both surfaces of the substrate on which the inner layer circuit is formed (S2); Attaching a photosensitive resin on the substrate on which the conductive material is laminated to form a via hole pad part and a dummy pattern, and then performing electroplating on the exposed via hole and the pad part (S3); Peeling the photosensitive resin to remove the conductive material, and then performing pretreatment or roughness treatment to improve adhesion to the insulating resin (S4); Forming an insulating layer on the pretreated or roughened substrate (S5); Polishing the insulating layer (S6); Forming a conductive land for the via hole on the polished substrate (S7); And And repeating steps (S1) to (S7) to form a build-up multilayer printed circuit board (S8). The method of claim 1, wherein in step (S2), after depositing the electroless chemical copper to a predetermined thickness on both sides of the substrate on which the inner layer circuit is formed, the photosensitive film is attached and only the conductive via hole and the dummy pattern are ultraviolet light. A method of manufacturing a multilayer printed circuit board, wherein the copper layer on the inner layer circuit is exposed by dissolving and developing only the unexposed portion by using Na ₂ CO ₃ solution in a blocked state. The method of claim 1, wherein in the step (S5), in order to protect the via-hole plating layer, 30 to 110 μm on one or both surfaces of the pretreated or roughened substrate by applying a thermosetting epoxy resin using an applicator and a printing machine over a first to third order. A method for manufacturing a multilayer printed circuit board, characterized in that laminated on a thickness. The method of claim 1, wherein in step S7, the surface of the polished substrate is desmeared to give roughness to improve the bonding strength of chemical copper, and then chemical copper plating to a predetermined thickness on the entire surface. And then performing an aging treatment at 80 to 110 ° C. for 30 to 50 minutes, followed by pattern or panel electroplating.