CN1630458A - Method for forming metal wire pattern by inkjet method - Google Patents

Abstract

The invention relates to a method for forming metal wire pattern by ink-jet method, which sprays catalyst on the part of substrate where metal wire is to be formed by micro-droplet spraying, then carries out electroless plating process to form metal wire, and in order to make catalyst effectively adsorbed on the substrate and improve surface property of substrate, the substrate needs proper surface modification treatment before micro-droplet spraying.

Description

Method for forming metal wire pattern by inkjet method

technical field

The invention relates to a method for forming a metal wire, in particular to a method for forming a metal wire pattern by an inkjet method.

Background technique

As electronic products move towards the design concept of "thin, thin and small", printed circuit boards (Printed Circuit Board, PCB) are also developing towards small aperture, high density, multi-layer, and thin lines. General printed circuit boards usually use glass fiber cloth or a flat substrate composed of a soft substrate. Using adhesives and hot pressing, attach a metal layer or copper foil and then etch to form metal wires. However, the formula of the adhesive needs to add a halogen-containing flame retardant, and it is difficult to comply with the European Union's 2004 ban on halogens in electronic products, which will limit its future development. Moreover, ionic impurities are often added to the adhesive, which deteriorates the dielectric and insulating properties of the substrate, and easily causes distortion and deformation of the substrate at high temperature, which will reduce the reliability of the substrate. Therefore, the use of adhesives should be avoided in circuit boards as much as possible.

Therefore, a metal layer can be formed on the surface of the substrate by metal deposition, and then the required metal wires can be etched out by photolithography. Electroless plating, or chemical plating, is a method of depositing a metal layer. In the absence of an external voltage, the metal ions in the solution are deposited on the metal through an autocatalytic chemical reaction. on a solid surface. This reaction procedure is very similar to electroplating, the difference is that the electron transfer does not pass through the external circuit when the reaction occurs, but is directly transferred on the surface when the substance in the solution undergoes a redox reaction on the solid surface. It is different from the electroplating of external circuits. In order to meet the thin line width requirements of the circuit board, it increases the difficulty of mask fabrication and metal layer etching, and metal wires of different types and sizes need to be fabricated with different masks, which relatively increases the manufacturing cost.

Therefore, by virtue of the characteristics of electroless plating, a method of directly forming metal patterns on the substrate as metal wires has been developed. Since electroless plating needs to be performed on an activated or catalyzed surface, metal wires can be selectively grown on the surface of the substrate. A catalytic layer is formed, followed by electroless plating. As described in U.S. Patent No. 6,521,285, a selective electroless plating method is disclosed. A printed board with a metal wire pattern is carved in advance, and then the printed board is dipped in a catalyst, and the printed board is aligned and pressed on the printed board by stamping. On the substrate, after the catalyst layer is printed on the surface of the substrate where the metal wires are to be formed, the conductive metal is grown on the surface of the substrate with the catalyst by electroless plating. This method also needs to make different printed boards with catalysts of different types and sizes of metal wires, and the line width of the circuit depends on the achievable engraving precision of the printed board.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for forming a metal wire pattern by inkjet method, which is to spray a catalyst on the substrate where the metal wire is to be formed in the form of micro-droplet spraying, and then perform an electroless plating process to form a metal wire , avoiding the use of adhesives. In addition, in order to effectively adsorb the catalyst on the substrate and improve the surface properties of the substrate, the substrate needs to undergo appropriate surface modification treatment before spraying the micro-droplets.

In order to achieve the above object, the present invention provides a method for forming a metal wire pattern by an inkjet method, which is characterized in that the steps include:

providing a substrate;

Spraying a catalyst on the surface of the substrate where metal wires are to be formed by means of micro-droplet spraying to form a metal catalytic pattern; and

A metal is deposited on the surface of the substrate having the metal catalytic pattern in an electroless manner to form a metal wire.

The above-mentioned method of forming a metal wire pattern by an inkjet method is characterized in that it also includes a step of performing a modification treatment on the surface of the substrate, so that the surface of the substrate forms a self-composed thin film interface, so that the catalyst can be effectively adsorbed on the surface of the substrate. the substrate surface.

The above-mentioned method for forming a metal wire pattern by an inkjet method is characterized in that the step of performing a modification treatment on the surface of the substrate includes:

Step a, immersing the substrate in an anionic polyelectrolyte solution;

Step b, immersing the substrate in a cationic polyelectrolyte solution;

step c, repeating steps a to b more than once; and

Step d, immersing the substrate in the anionic polyelectrolyte solution.

The above-mentioned method for forming metal wire pattern by inkjet method is characterized in that the anionic polyelectrolyte solution is selected from polyacrylic acid solution, polymethacrylic acid and polysiphene-3-acetic acid.

The above-mentioned method for forming metal wire pattern by inkjet method is characterized in that the cationic polyelectrolyte solution is selected from the group consisting of polyallylamine hydrogen chloride solution, polyethylpyrazole, polyethylpyrrolidone and polyaniline.

The above-mentioned method for forming a metal wire pattern by an inkjet method is characterized in that the substrate is selected from a glass substrate, a polyester substrate, an organic glass fiber substrate, a flexible organic glass fiber substrate and a polyimide substrate.

The above-mentioned method for forming a metal wire pattern by an inkjet method is characterized in that the step of performing a modification treatment on the surface of the substrate includes:

Step a, soaking the substrate in a cationic polyelectrolyte solution;

Step b, immersing the substrate in an anionic polyelectrolyte solution;

step c, repeating steps a to b more than once; and

Step d, immersing the substrate in the anionic polyelectrolyte solution.

The above-mentioned method for forming metal wire pattern by inkjet method is characterized in that the anionic polyelectrolyte solution is selected from polyacrylic acid solution, polymethacrylic acid and polysiphene-3-acetic acid.

The above-mentioned method for forming metal wire pattern by inkjet method is characterized in that the cationic polyelectrolyte solution is selected from the group consisting of polyallylamine hydrogen chloride solution, polyethylpyrazole, polyethylpyrrolidone and polyaniline.

The above-mentioned method for forming metal wire pattern by inkjet method is characterized in that it further includes a step of providing a wave to the substrate to planarize the metal catalytic pattern on the surface of the substrate.

The above-mentioned method of forming a metal wiring pattern by an inkjet method is characterized in that the main component material of the metal is copper.

The above-mentioned method for forming metal wire pattern by inkjet method is characterized in that the catalyst is selected from sodium tetrachloropalladate solution and tetraammonia palladium dichloride solution.

The above-mentioned method for forming a metal wire pattern by an inkjet method is characterized in that it also includes the following steps:

Spraying another layer of metal catalytic pattern on the surface of the first metal wire by inkjet; and

Electroless plating is performed to deposit another layer of metal on the surface of the metal wire to form another metal wire.

The above-mentioned method of forming a metal wire pattern by an inkjet method is characterized in that the main component materials of the two metals are different.

Surface modification is carried out by forming a self-assembled monolayer (SAM) interface on the substrate surface. The self-assembled monolayer interface formed after the substrate surface treatment uses the chemical kinetic difference between atoms to induce self-assembled ( self-assembly) to form a special nano-interface structure, the nano-interface structure has a thickness of nanometer size. The film-forming mechanism of the self-assembled thin film can form a two-dimensional ordered monolayer with chemically bonded atoms closely arranged on the substrate by chemical adsorption between the solid-liquid interface. Repeatedly controlling the formation of this self-composed thin film can form a nanoscale multilayer film interface structure, and the composition, structure, physical and chemical properties of the thin film interface can be used to change the surface properties of the substrate, and make the substrate surface resistant to certain substances. Selective adsorption capacity, whereby the substrate can effectively adsorb the catalyst.

By spraying the catalyst on the substrate where the metal wire is to be formed, the line width of the metal wire formed by subsequent electroless plating can be effectively reduced and stably controlled. Based on the characteristics of electroless plating, the thickness of the metal wire can be easily controlled and the resistance of the metal wire can be reduced. Cooperating with micro-droplet spraying and electroless plating methods, compared with the existing photolithography and etching processes, the production of metal wires can be quickly completed and the production rate can be improved.

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments, but not as a limitation of the present invention.

Description of drawings

Fig. 1 is the flow chart of the method for forming metal wire pattern with ink-jet method of the present invention;

Fig. 2 present invention is with the schematic diagram of the device of ink-jet method spraying metal catalytic pattern;

3 is a schematic cross-sectional view of a circuit board according to a first embodiment of the present invention; and

FIG. 4 is a schematic cross-sectional view of a circuit board according to a second embodiment of the present invention.

Detailed ways

Please refer to FIG. 1 , which is a flow chart of a method for forming a metal wire pattern by an inkjet method. First, in step 110 , the substrate is cleaned and subjected to UV-ozone (UV-ozone) treatment for 10 minutes. Step 120, soaking the substrate in an anionic polyelectrolyte solution, the anionic polyelectrolyte solution is poly(acrylic acid) (PAA) with a concentration of 10 millimolar (M). Step 130, cleaning the substrate with deionized water. Step 140, soaking the substrate in a cationic polyelectrolyte solution, the cationic polyelectrolyte solution is poly(allylamine hydrochloride, PAH) with a concentration of 10 millimolar (M). Step 150, soaking the substrate in an anionic polyelectrolyte solution. In step 160, a catalyst is sprayed on the substrate where metal wires are to be formed by means of micro-droplet spraying. The catalyst is a sodium tetrachloropalladate (Na2PdCl4) solution with a concentration of 10 millimolar (M). Step 170, cleaning the substrate with deionized water. Then soak the substrate in a hydrogen chloride solution with a pH value between 2.5 and 3 for 30 seconds; then, step 180 , perform electroless metal plating. Finally, in step 190, the substrate is rinsed with deionized water.

Among them, steps 120 to 140 of the present invention are used to carry out the surface modification treatment of the substrate. The surface modification is performed by forming a self-composed thin film interface on the surface of the substrate, and the sequence of immersing the cationic and anionic polyelectrolyte solutions in conjunction with substrates of different materials It could also be the other way around. The substrate is soaked in two polyelectrolyte solutions with different electrical properties, and a self-composed thin film interface can be formed on the surface. In the above process, in order to effectively change its surface properties, it is also possible to repeat steps 120 to 140 to stack multiple PAH/PAA double-layer structures (bilayers) on the substrate surface, and then perform step 150 to form nanoscale multilayer self-organization membrane interface. The structure of the self-composed thin film interface can be selected based on the properties of different material substrates. The applicable substrate materials for the above-mentioned PAH/PAA bilayers can be glass substrates, polyester (PET) substrates, organic glass fiber (FR-4) substrates, flexible Flexible plexiglass fiber substrate (Flexible FR-4) and polyimide substrate (Polyimide). In addition, its cationic polyelectrolyte solution can be selected from polypropylene amine hydrogen chloride solution (PAH), polyethylpyrazole (PVI+), polyethylpyrrolidone (PVP+) and polyaniline (PAN); The polyelectrolyte solution may be selected from polyacrylic acid solution (PAA), polymethacrylic acid (PMA) and polysiphen-3-acetic acid (PTAA).

In the present invention, the catalyst is sprayed on the place where the metal wire is to be formed on the substrate by the inkjet printing method. Since the catalyst is generally a salt, it can be almost completely dissolved in water to form a uniform solution, so it has good inkjet stability. Since the metal wires formed by the subsequent electroless plating depend on the inkjet resolution, and the current inkjet technology can achieve high resolution, the present invention can be used to make metal wires with high density and fine line width. In addition, in order to increase the flatness of sprayed catalyst droplets, fluctuations of appropriate frequency and amplitude can be provided during inkjet to destroy the surface tension of micro-droplets attached to the substrate, resulting in a flatter film uniformity.

Please refer to FIG. 2 , which is a schematic diagram of an apparatus for spraying metal catalytic patterns by inkjet method. Including an inkjet head module 10, a moving platform 20, a support frame 21, and a wave generation module 30, the inkjet head module 10 has more than one nozzle hole 11, and is fixed on a nozzle adjustment mechanism 12 to apply catalyst liquid to the substrate 40. Drop 13 for spraying. The moving carrying platform 20 is carrying the substrate 40 and its position can be adjusted for spraying the catalyst droplets 13 by the inkjet head module 10 , and has a support frame 21 for the substrate to be set to keep a certain distance between the substrate 40 and the moving carrying platform 20 . The wave generating module 30 is a piezoelectric component attached to the bottom of the substrate 40 , and the wave generating module 30 is not in contact with the motion bearing platform 20 , which can avoid unnecessary energy attenuation. The fluctuation generation module 30 operates to generate fluctuations of appropriate frequency. When the spray hole 11 sprays a plurality of catalyst droplets 13 on the substrate 40 to form a metal catalytic pattern, a flattened metal catalytic pattern can be obtained after the solvent of the catalyst droplets volatilizes. . The above process uses sodium tetrachloropalladate (Na2PdCl4) solution or tetraammonia palladium dichloride (Pd(NH3)4Cl2) solution as a catalyst, and catalyzes metals such as electroless copper plating by precipitating palladium.

Electroless plating is also called chemical plating or autocatalytic plating. Electroless plating means that the metal ions in the aqueous solution are chemically reduced under a controlled plating solution environment to form a plating layer on the substrate. The general electroless plating solution mainly needs to contain metal ions (metal ions) as the source of plating metal; reduce metal ions to metal reducing agent (reducing agent); make the surface of the substrate catalytic (catalyst). Secondly, in order to maintain the stability of the plating solution, it is necessary to include a complexing agent to prevent precipitation of hydroxides, adjust the precipitation rate, prevent the decomposition of the plating solution, and stabilize the plating solution; absorb particulate impurities to prevent the natural decomposition of the plating solution, so as to prolong the life of the plating solution. Stabilizer (stabilizer) for bath life; and buffer (buffer) to control pH value within the operating range. And in order to increase the properties of the coating, it is necessary to add a wetting agent (wetting agent) to make the surface work well; a brightener (brightener) to make the coating have good gloss.

The electroless plating solution needs to be stable, and it needs to be inactive when not in use, and only starts to act and precipitate the metal coating when the catalytic surface is in contact. In the present invention, the surface modification treatment is carried out on the substrate first, and then the catalyst is sprayed on the place where the metal wire is to be formed on the substrate, and then electroless plating is performed to selectively deposit metal only on the surface with the catalyst to form the metal wire. Please refer to FIG. 3 , which is a schematic cross-sectional view of a circuit board according to a first embodiment of the present invention. The surface of the substrate 200 is modified to have a multilayer self-organized thin film interface 210 composed of a PAA layer 211 and a PAH layer 212. The metal catalytic pattern 220 is sprayed and attached to the multilayer self-assembled thin film interface 210. The first metal wire 230 is formed on the metal catalytic pattern 220 .

Since the speed of electroless plating will decrease after a period of time, the method of the present invention is applied, as shown in FIG. 4 , which is a schematic cross-sectional view of a circuit board according to the second embodiment of the present invention. Another metal catalytic pattern 221 can be sprayed on the first metal wire, and a second electroless plating is performed again to form the second metal wire 231 . At the same time, in addition to using the same catalyst and electroless plating bath to increase the thickness of the metal wire pattern, different catalysts and electroless plating solutions can be selected, so that the first metal wire and the second metal wire can be formed of the same or different metal materials.

Certainly, the present invention also can have other multiple embodiments, without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding Changes and deformations should belong to the scope of protection of the appended claims of the present invention.

Claims (14)

1, a kind of method with ink-jet method formation metal conductive line pattern is characterized in that step includes:

One substrate is provided;

Form the plain conductor part with little drop spraying method in this substrate surface desire and spray a catalyst to form a metal catalytic pattern; And

Have this metal catalytic pattern part in the electroless plating mode at this substrate surface and deposit a metal to form a plain conductor.

2, the method that forms metal conductive line pattern with ink-jet method according to claim 1, it is characterized in that, also comprise one and carry out the step that a upgrading is handled, this substrate surface is formed from forming the film interface, so that this catalyst can effectively be adsorbed in this substrate surface at this substrate surface.

3, the method with ink-jet method formation metal conductive line pattern according to claim 2 is characterized in that, described step of carrying out upgrading processing at this substrate surface comprises:

Step a, with this substrate immersion in an anionic polyelectrolyte solution;

Step b, with this substrate immersion in a cationic polymerization electrolyte solution;

Step c, repeat once above step a to step b; And

Steps d, with this substrate immersion in this anionic polyelectrolyte solution.

4, the method with ink-jet method formation metal conductive line pattern according to claim 3 is characterized in that, this anionic polyelectrolyte solution is selected from polyacrylic acid solution, polymethylacrylic acid and poly-match fen-3-acetic acid.

5, the method with ink-jet method formation metal conductive line pattern according to claim 3 is characterized in that, this cationic polymerization electrolyte solution is selected from polypropylene amine hydrogen chloride solution, poly-ethyl pyrazoles, poly-N-ethyl pyrrole N-ketone and polyaniline.

6, the method with ink-jet method formation metal conductive line pattern according to claim 3 is characterized in that this substrate is selected from glass substrate, polyester substrate, polymethyl methacrylate fibre base plate, pliability polymethyl methacrylate fibre base plate and Polyimide substrate.

7, the method with ink-jet method formation metal conductive line pattern according to claim 2 is characterized in that, described step of carrying out upgrading processing at this substrate surface comprises:

Step a, with this substrate immersion in a cationic polymerization electrolyte solution;

Step b, with this substrate immersion in an anionic polyelectrolyte solution;

Step c, repeat once above step a to step b; And

Steps d, with this substrate immersion in this anionic polyelectrolyte solution.

8, the method with ink-jet method formation metal conductive line pattern according to claim 7 is characterized in that, this anionic polyelectrolyte solution is selected from polyacrylic acid solution, polymethylacrylic acid and poly-match fen-3-acetic acid.

9, the method with ink-jet method formation metal conductive line pattern according to claim 7 is characterized in that, this cationic polymerization electrolyte solution is selected from polypropylene amine hydrogen chloride solution, poly-ethyl pyrazoles, poly-N-ethyl pyrrole N-ketone and polyaniline.

10, the method with ink-jet method formation metal conductive line pattern according to claim 1 is characterized in that, also comprising one provides the step of a fluctuation to this substrate, with this metal catalytic pattern of this substrate surface of planarization.

11, the method with ink-jet method formation metal conductive line pattern according to claim 1 is characterized in that the principal component material of this metal is a copper.

12, the method with ink-jet method formation metal conductive line pattern according to claim 1 is characterized in that this catalyst is selected from tetrachloro-palladium acid sodium solution and four hydrazine dichloride palladium solution.

13, the method with ink-jet method formation metal conductive line pattern according to claim 1 is characterized in that, also comprises the following step:

Spray another layer metal catalytic pattern with ink-jetting style on this first plain conductor surface; And

Carry out electroless plating at this another layer of plain conductor surface deposition metal to form another plain conductor.

14, the electroless process with ink-jet method formation metal catalytic pattern according to claim 13 is characterized in that the principal component material difference of these two kinds of metals.