KR20210006251A - Method for forming multilayer pcb using three dimensional printing - Google Patents

Abstract

According to the present invention, a method for forming a multilayer printed circuit board by three-dimensional printing comprises: a step of forming an inner layer circuit with copper foil on the surface of an inner layer core; a step of laminating a plurality of inner layer cores having the inner layer circuit; a step of forming an outer layer circuit with copper foil on the surface of a multilayer board formed by the lamination; a step of using nonconductive liquid ink to form a marking for identification on the surface of the outer layer circuit in the multilayer board; and a step of forming a conductive film on the surface of a copper foil circuit formed on the surface of the outer layer board. The step of forming the marking and the step of forming the conductive film form the marking and the conductive film by spraying nonconductive liquid ink and conductive ink by three-dimensional printing. The present invention can drastically reduce manufacturing costs by increasing the manufacturing efficiency of a multilayer printed circuit board, and efficiently design a circuit and various terminal units since a lead wire for plating for forming a conductive film does not need to be separately formed on an outer layer board. Also, since a plating process for forming a conductive film is not needed, the multilayer printed circuit board can be manufactured in an eco-friendly manner by eliminating processes that use various chemical solutions for plating.

Description

Method of forming multi-layer printed circuit board by 3D printing method {METHOD FOR FORMING MULTILAYER PCB USING THREE DIMENSIONAL PRINTING}

The present invention relates to a method of forming a multilayer printed circuit board, and more particularly, by using a three-dimensional printing method, manufacturing efficiency can be increased, thereby dramatically reducing the cost of manufacturing a multilayer printed circuit board, and space efficient design of the substrate becomes possible. , The present invention relates to a method of forming a multilayer printed circuit board by a three-dimensional printing method, which is configured to improve electrical characteristics of a circuit and reduce the occurrence of various harmful substances.

In recent years, electronic product-related technologies are progressing toward multifunctional and high-speed trends, and semiconductor chip manufacturing technologies are also developing at a rapid pace to cope with this trend.

In particular, the thickness of printed circuit boards (PCBs), which are applied to make finished electronic products light, thin, and short, is also decreasing, and technology related to multi-layer printed circuit boards comprising more circuit layers within a printed circuit board of the same thickness. Are being actively developed.

In general, a multilayer printed circuit board includes a prepreg (insulator) formed by impregnating a glass fiber with an epoxy resin and a printed circuit board including a copper foil (cu) circuit formed on the surface thereof. It can be formed by heat-pressing bonding in a state.

In some cases, separate components such as memory chips are connected to a specific area of the multilayer printed circuit board, and in this case, a cavity (recess) is formed to reduce the thickness of the entire circuit board, and the mounting component is disposed inside the cavity.

1 is a partially enlarged view of an outer surface of a conventional multilayer printed circuit board 100.

Circuits formed on the outer surface of the conventional multilayer printed circuit board 100, various pads 110 and terminal 120 are also formed of copper foil, and surface treatment suitable for use on the surfaces of the pads 110 and terminal 120 Do it. The pad 110 mainly uses OSP, electroless plating (ENIG), electroless tin plating, etc. for soldering, and electrolytic soft gold plating for wire bonding.

The terminal portion 120 is usually subjected to electrolytic hard gold plating.

In order to process electrolytic plating, the lead wire 130 for plating is required, so it must be additionally formed.

Thus, by performing a plating process in a state in which electricity is applied to the plating lead wire 130, a conductive film is formed on the terminal portion.

In the state in which the conductive film is formed as described above, a marking 140 for identifying components to be connected to the various pads 110 is printed again.

However, in order to form an electrolytic plating film on a conventional multilayer printed circuit board, as described above, a plating lead wire 130 must be additionally formed on the surface of the outer substrate in addition to various pads and terminal portions.

Therefore, in addition to the inefficiency in the process of additionally designing and forming the plating lead wire 130, a certain area for arranging the plating lead wire must be separately provided on the surface of the outer layer substrate, so that the circuit and terminals are arranged. There is a problem that the space for doing so is reduced.

In addition, as the electrical signal transmission speed increases as the frequency increases, an electrical noise problem has also emerged due to the plating lead wire 130.

In addition, since the marking 140 must be printed after forming a film on the surface of the terminal portion through the plating lead wire 130 in a plating method and drying, the process for manufacturing a multilayer printed circuit board is somewhat inefficient. There is.

The present invention was devised to solve the above problems, and an object of the present invention is to increase manufacturing efficiency by using a three-dimensional printing method to form a conductive film and marking, thereby dramatically reducing the cost of manufacturing a multilayer printed circuit board. It is to provide a method of forming a multilayer printed circuit board by a three-dimensional printing method that is configured to be able to be used.

Another object of the present invention is to provide a three-dimensional printing method configured to allow the design of circuits, various pads, and terminals in a more space efficient manner, since it is not necessary to separately form a plating lead for forming an electrolytic plating film on the outer substrate. It is to provide a method of forming a multilayer printed circuit board by.

Another object of the present invention is that a plating process for forming a conductive film is unnecessary, so a process of using various chemical solutions required for plating is eliminated, and thus, a three-dimensional printing method that is configured to enable more environmentally friendly manufacturing of a multilayer printed circuit board is used. It is to provide a method of forming a multilayer printed circuit board.

A method of forming a multilayer printed circuit board by a three-dimensional printing method according to the present invention for achieving the above object

Forming an inner layer circuit on an inner layer CCL (Core), stacking a plurality of inner layer CCLs, forming an outer layer circuit on the surface of the stacked multilayer substrate, and removing the SMC pads and terminals excluding the PSR (Photo Solder Resist). ) Coating with ink, forming a marking on the PSR surface using a non-conductive liquid ink, and forming a conductive film on the exposed copper (copper) surface because the PSR is not applied, the The forming of the marking and the forming of the conductive film are characterized in that they are formed by spraying non-conductive liquid ink and conductive ink by a three-dimensional printing method.

Preferably, the conductive ink is formed of a conductive ink containing a gold component.

In addition, the marking and the conductive film may be formed simultaneously by a single process.

Here, the conductive ink includes gold nanoparticles, a solvent, a dispersant, and a wetting agent.

In addition, the conductive ink may include silver nanoparticles, tin nanoparticles, and copper nanoparticles.

In addition, the conductive ink may include cobalt nanoparticles.

Preferably, based on 100 parts by weight of the conductive ink composition, 70 to 80 parts by weight of gold nanoparticles are included, 4 to 5 parts by weight of the silver nanoparticles are included, and 15 to 25 parts by weight of the tin nanoparticles are included, and , The copper nanoparticles are included in 0.5 to 1 parts by weight, and the cobalt nanoparticles are included in 0.001 to 0.1 parts by weight.

According to the present invention, the manufacturing cost can be drastically reduced by increasing the manufacturing efficiency of the multilayer printed circuit board.

In addition, there is no need to separately form a plating lead portion for forming a conductive film on the outer layer substrate, so that a wider area for arranging circuits, various pads, and terminal portions on the outer layer substrate can be secured.

In addition, since the plating process for forming the conductive film is unnecessary, the process of using various chemical solutions used for plating is eliminated, so that the production of a multilayer printed circuit board is possible in an environment-friendly manner.

The accompanying drawings are for understanding the technical idea of the present invention together with the detailed description of the present invention, and the present invention should not be construed as being limited to the matters shown in the drawings.
1 is a partially enlarged view of the surface of an outer substrate in a conventional multilayer printed circuit board,
2 is a flowchart showing a method of forming a multilayer printed circuit board by a three-dimensional printing method according to the present invention,
3 is a partially enlarged view of the surface of the outer substrate of the multilayer printed circuit board,
4 is an exemplary view showing a method of forming a multilayer printed circuit board according to the present invention.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.

Prior to this, terms used in the present specification and claims should not be construed as limited in a dictionary meaning, and based on the principle that the inventor can appropriately define the concept of terms in order to describe his invention in the best way. , It should be interpreted as a meaning and concept consistent with the technical idea of the present invention.

Accordingly, the embodiments described in the present specification and the configurations shown in the drawings are only preferred embodiments of the present invention, and do not represent all the technical ideas of the present invention, and various equivalents that can replace them at the time of the present application It should be understood that water and variations may exist.

FIG. 2 is a flowchart showing a method of forming a multilayer printed circuit board by a three-dimensional printing method according to the present invention, FIG. 3 is a partially enlarged view of the surface of an outer layer of a multilayer printed circuit board, and FIG. 4 is a multilayer printing according to the present invention. It is an exemplary diagram showing a method of forming a circuit board.

In the method of forming a multilayer printed circuit board by a three-dimensional printing method according to the present invention, the steps of forming an inner layer circuit with copper foil on the surface of an inner layer core (S 10) and stacking a plurality of inner layer cores having the inner layer circuit formed thereon (S 20), forming an outer layer circuit with copper foil on the surface of the multilayer substrate formed by lamination (S30), and marking for identification on the surface of the outer layer substrate in the multilayer substrate using non-conductive liquid ink Forming (S 40) and forming a conductive film on the surface of the copper foil circuit formed on the outer substrate surface (S 50), the step of forming the marking (S 40) and forming a conductive film Step (S50) is characterized in that formed by spraying non-conductive liquid ink and conductive ink by a three-dimensional printing method.

The substrate is formed including various circuits and terminal portions by attaching a dry film to the surface of the copper foil in a state in which copper foil is disposed on the surface of the prepreg, and undergoing exposure, development, and copper foil etching processes (S 10 ).

The prepreg is formed by impregnating a polymer resin with a reinforcing base material such as glass fiber, and as the reinforcing base material, a glass fiber fabric, a glass fiber nonwoven fabric, a carbon fiber fabric, or an organic polymer fiber fabric is used.

In addition, the polymer resin for forming the prepreg is mixed with additives such as a curing agent for controlling dielectric constant, thermal expansion coefficient, and time required for curing.

Examples of additives mixed with the polymer resin to control the above properties include inorganic fillers such as silica, aluminum hydroxide, and calcium carbonate, and organic fillers such as cured epoxy and crosslinked acrylic.

Circuit patterns formed on each substrate by copper foil may be formed to a thickness of about 15 to 20 μm.

In addition, a multilayer circuit board is formed by stacking a plurality of individual substrates formed as described above and applying heat and pressure (S20).

The outer layer circuit disposed outside the multilayer circuit board formed by stacking is also formed by exposing, developing, and etching copper foil on the surface (S 30 ).

In the state in which the multilayer substrate is formed as described above, cavities for arranging various components such as memory components may be formed on the surfaces of the uppermost outer layer substrate and the lowermost outer layer substrate.

As shown in FIG. 3, various circuits 10, various pads 20, and terminal portions 30 are formed on the surface of the outer substrate, and a conductive film should be formed on the copper foil surface on which the terminal portions 30 are formed. .

In addition, a marking 40 for identifying the part to be connected must be marked.

In the present invention, a marking 40 for identification is formed on the surface of the outer substrate by a three-dimensional printing method using non-conductive liquid ink, and conductive ink is sprayed on the surface of the copper foil circuit 10 formed on the outer substrate surface. To form a conductive film.

That is, as shown in FIG. 4, the non-conductive liquid ink and the conductive ink are sprayed through the printing nozzles 52 and 54 to form the marking 40 and the conductive film.

The nozzle head 50 in which the printing nozzles 52 and 54 are installed is configured to be movable in the horizontal, vertical, and height directions, so that the terminal part 30 is formed higher than the inside of the cavity for component mounting or the circuit 10 As described above, even when a height difference occurs, it is configured to spray conductive ink or non-conductive liquid ink.

Preferably, the non-conductive liquid ink is composed of a white color, and is sprayed through one nozzle 52, and the conductive ink may be sprayed through the other nozzle 54.

In addition, the marking 40 and the conductive film may be formed simultaneously by a single process.

Here, the meaning of “simultaneous” means that the marking 40 and the conductive film can be formed together by a single three-dimensional printing device, rather than a complete simultaneous in time.

That is, it means that the marking 40 and the conductive film are formed by one 3D printing device in a single process.

The conductive film is meant to be formed by including a gold component in a conductive ink, and includes gold nanoparticles obtained by pulverizing gold into nanoparticles, a solvent, a dispersant, and a wetting agent.

The dispersant is an additive for maintaining the gold nanoparticles stably dispersed in the ink, and the wetting agent is an additive for preventing clogging (clogging) in the printing nozzle.

Preferably, the conductive ink is formed to have a viscosity in the range of 35 to 45 mPa·s and a surface tension in the range of 15 to 18 mN/m, including a dispersant and a wetting agent.

Inkjet printing is largely divided into a continuous injection method and a drop-on-demand method according to the ink injection method.

The continuous injection method is a method of printing by adjusting the direction of ink by changing an electromagnetic field while spraying ink using a pump, and the drop-on-demand method is a method of injecting ink only when necessary through an electrical signal. Accordingly, it can be divided into a piezoelectric method that generates pressure by causing the deformation of the piezoelectric plate, and a thermal transfer method that uses the pressure generated from expansion of the bubble by heat.

The conductive ink of the present invention must satisfy the properties of the fluid to be sprayed from the printing nozzle and the properties of the metal particles to form the conductive metal pattern.

The physical properties of the fluid that must be satisfied in order for the conductive ink to be ejected from the nozzle, as appropriate viscosity and surface tension, affect the ejection speed at a constant pressure pulse.

In addition, not only physical properties of the fluid such as viscosity, surface tension, and conductivity, which greatly affect spraying, but also chemical stability, dispersibility, and changes in properties over time related to the stability of the ink should be considered.

If the physical properties of the fluid are not satisfied, the ejection state of ink may be unstable or may not be ejected.

In addition, physical properties of the metal particles to be satisfied in order to form the conductive metal pattern include high conductivity and oxidation resistance of the metal particles, suitable size of metal nanoparticles, and maintaining a stable dispersion state in ink.

Here, it may include silver nanoparticles, tin nanoparticles, and copper nanoparticles to have conductivity and oxidation resistance.

In addition, cobalt nanoparticles may be included in the conductive ink according to the present invention to improve heat resistance and corrosion resistance.

In the present invention, the size of the metal nanoparticles contained in the ink composition is preferably in the range of 10 to 30 nm.

The dispersant is included to stably disperse the metal nanoparticles of high concentration in the ink.

The solvent may be one or more of ethanol, methanol, acetone, isopropyl alcohol, toluene, and methyl ethyl ketone.

The content of the solvent is preferably 10 to 50 parts by weight based on 100 parts by weight of the ink composition.

If the content of the solvent exceeds 50 parts by weight, the density of the metal nanoparticles decreases, so that excellent anti-oxidation film properties are not exhibited, and if the content of the solvent is less than 10 parts by weight, the viscosity becomes too high and spraying becomes unstable.

Preferably, based on 100 parts by weight of the conductive ink composition, 70 to 80 parts by weight of gold nanoparticles are included, 4 to 5 parts by weight of the silver nanoparticles are included, and 15 to 25 parts by weight of the tin nanoparticles are included, and , The copper nanoparticles are included in 0.5 to 1 parts by weight, and the cobalt nanoparticles are included in 0.001 to 0.1 parts by weight.

If the content of the gold nanoparticles is less than 70 parts by weight, the density of the gold nanoparticles of the conductive antioxidant film decreases, so that excellent conductivity and antioxidant performance are not exhibited.

If it exceeds 80 parts by weight, the viscosity of the ink becomes too large, making spraying unstable, and there is a problem in that the cost of manufacturing the conductive ink increases dramatically.

If the content of the silver nanoparticles is less than 4 parts by weight, the density of the silver nanoparticles decreases, so that excellent conductivity and anti-oxidation performance cannot be exhibited, and if the content of the silver nanoparticles exceeds 5 parts by weight, the ink viscosity becomes too high, resulting in unstable injection.

In addition, it is preferable that tin nanoparticles, copper nanoparticles, and cobalt nanoparticles are included in the above ranges for appropriate conductivity and oxidation resistance.

The dispersant serves to keep the metal nanoparticles of high concentration in a stably dispersed state in the ink, and the content of the dispersant is preferably 2 to 5 parts by weight based on 100 parts by weight of the ink composition.

When the content of the dispersant exceeds 5 parts by weight, the viscosity increases due to the mutual influence of the polymers of the dispersant, resulting in unstable spraying. If the content of the dispersant is less than 2 parts by weight, the role of the dispersant is insignificant, resulting in poor dispersion stability.

In order to prevent nozzle clogging of the inkjet printer, the humectant controls the properties of the solvent so as to maintain wettability, and the content of the humectant is preferably 2 to 5 parts by weight based on 100 parts by weight of the ink composition.

If the content of the humectant exceeds 5 parts by weight, the viscosity increases significantly and spraying becomes unstable, and if the content of the humectant is less than 2 parts by weight, clogging of the nozzle may occur.

In the above, although the present invention has been described by the limited embodiments and drawings, the technical idea of the present invention is not limited to these, and by those of ordinary skill in the art to which the present invention pertains, the technical idea of the present invention and Various modifications and variations will be possible within the scope of the following claims.

10: circuit
20: Pad
30: terminal part
40: marking
50: nozzle head

Claims (7)

Forming an inner layer circuit with copper foil on a surface of the inner layer core;
Stacking a plurality of inner layer cores having the inner layer circuit formed thereon;
Forming an outer layer circuit with copper foil on the surface of the multilayer substrate formed by lamination;
Forming a marking for identification on the surface of the outer substrate in the multilayer substrate using non-conductive liquid ink;
And forming a conductive film on the surface of the copper foil circuit formed on the surface of the outer substrate,
The forming of the marking and the forming of the conductive film are formed by spraying non-conductive liquid ink and conductive ink by a three-dimensional printing method.The method of forming a multilayer printed circuit board by a three-dimensional printing method. The method of claim 1,
The method of forming a multilayer printed circuit board by a three-dimensional printing method, characterized in that the conductive ink is formed of a conductive ink containing a gold component. The method of claim 2,
The method of forming a multilayer printed circuit board by a three-dimensional printing method, characterized in that the marking and the conductive film are formed simultaneously by a single process. The method of claim 2,
The conductive ink is a method of forming a multilayer printed circuit board by a three-dimensional printing method, characterized in that it contains gold nanoparticles, a solvent, a dispersant, and a wetting agent. The method of claim 4,
The conductive ink is a method of forming a multilayer printed circuit board by a three-dimensional printing method, characterized in that it contains silver nanoparticles, tin nanoparticles, and copper nanoparticles. The method of claim 5,
The method of forming a multilayer printed circuit board by a three-dimensional printing method, characterized in that the conductive ink contains cobalt nanoparticles. The method of claim 6,
Based on 100 parts by weight of the conductive ink composition, 70 to 80 parts by weight of gold nanoparticles are included, 4 to 5 parts by weight of the silver nanoparticles are included, and 15 to 25 parts by weight of the tin nanoparticles are included, and the copper nanoparticles A method of forming a multilayer printed circuit board by a three-dimensional printing method, characterized in that 0.5 to 1 parts by weight of the particles are included, and 0.001 to 0.1 parts by weight of the cobalt nanoparticles are included.

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