KR100645641B1 - Imprint mold for printed circuit board using ptfe and manufacturing method thereof - Google Patents

Abstract

An imprint mold for printed circuit board fabricated by using PTFE(polytetrafluoroethylene) is provided to embody the printed circuit board with excellent physical properties including releasing property, strength, thermal conductivity, durability, chemical-resistance, water-repellent property, self-lubrication, etc. by using electrolytic nickel plating solution dispersed with PTFE powder to form a nickel plated layer and having multiple via-holes and structure corresponding to circuit patterns. A method for fabricating imprint mold(300) comprises the steps of: (a) preparing a master mold(100) that includes multiple via-holes and patterns of a structure including circuit pattern; (b) forming a metal coating layer(200) on the master mold having the structure patterns; (c) preparing electrolytic nickel plating solution having PTFE(320) powder dispersion; (d) forming PTFE-charged nickel plating layer(310) by contacting the nickel plating solution with the master mold; (e) separating the nickel plating layer from the master mold; (f) heat-treating the separated nickel plating layer to partially decompose PTFE charged in the nickel plating layer.

Description

Imprint mold for printed circuit board using PTFE and manufacturing method

1A to 1B are views for explaining a release process of a nickel imprint mold according to the prior art.

2a to 2e are views for explaining a manufacturing process of an imprint mold for a printed circuit board according to an embodiment of the present invention.

3 is a view for explaining an electrolytic nickel plating process of manufacturing an imprint mold for a printed circuit board according to an embodiment of the present invention.

4 is a photograph of observations of the patterns of the imprint molds produced according to Examples 1 to 3 and Comparative Example 1 of the present invention, respectively, under a microscope (× 5).

5 is a photograph of the surface of the imprint mold prepared according to Examples 1 to 3 and Comparative Example 1 of the present invention observed with a scanning electron microscope (SEM: × 500 to 1000), respectively.

6A and 6B are photographs showing changes in the mold surface during repeated use of an imprint mold manufactured according to Example 1 and Comparative Example 1 of the present invention, respectively.

7A to 7D are views illustrating three-dimensional measurement values of an imprint mold manufactured according to Example 1 of the present invention and a film pattern imprinted using the same.

8A to 8D are diagrams illustrating three-dimensional measurement values of an imprint mold manufactured according to Comparative Example 1 of the present invention and an imprinted film pattern using the same.

※ Explanation of code about main part of drawing ※

10: mold for imprint

20: release layer

100: master mold

200: metal coating layer

300: nickel mold for imprint

310: electrolytic nickel plating layer

320: PTFE

311: nickel electrode

321: PTFE Powder

The present invention relates to an imprint mold for a printed circuit board using PTFE and a method of manufacturing the same. More specifically, an imprint mold for a printed circuit board using PTFE and a method for manufacturing the same, which have excellent durability and excellent pattern realization characteristics even after repeated use by manufacturing an imprint mold made of PTFE-filled electrolytic nickel plating layer will be.

Today, electronic and electric technology is rapidly evolving for more information storage, faster information processing and transmission, and simpler communication network to keep pace with the 21st century's high information and communication society.

In particular, under the condition of the finiteness of a given information transmission rate, as a method capable of meeting these requirements, a method for implementing the components as small as possible while increasing reliability and providing new functionality has been proposed.

As described above, in accordance with the trend of light and short size of electronic products, fine patterns, miniaturization, and packaging of printed circuit boards are also progressing simultaneously. Accordingly, a circuit having excellent signal processing capability in a smaller area may be implemented. To this end, the need for high-density substrate fabrication has emerged.

One of the most widely used microstructure fabrication techniques to date is photolithography, a method of forming a pattern on a substrate coated with a photoresist thin film.

However, when manufacturing a substrate using the UV lithography method, there are two limitations that the copper foil used as the circuit must be thick and the wet etching method is used. There is a problem that the reliability of the.

On the other hand, in recent years, the integration degree of printed circuit boards has become higher and accordingly researches on a method of forming a fine pattern have become more active. Thus, a high-density substrate is manufactured using an imprint method as an alternative method of the above-described UV lithography. Attempts are being made.

When manufacturing a large-area substrate such as a printed circuit board using this imprint process, a large area imprint process should be considered for mass production. In this case, the release problem between the imprint mold and the substrate becomes a problem to be solved. have.

Currently, the use of a nickel mold having excellent durability and easy plating as one of the imprinting molds is increasing, and thus, researches for improving releasability of the nickel mold are also being conducted.

In this regard, Figures 1a to 1b schematically shows the release process of the nickel mold for imprint according to the prior art.

1A to 1B, a conventional mold release agent such as epoxy, teflon or silicon is sprayed on a nickel mold 10 having a structure corresponding to a plurality of vias and patterns to be formed on a surface thereof; The release layer 20 is formed by a release process according to a conventional release layer forming method such as (PECVD), SAM (Self Assembly Monolayer) coating method or Diamond-Like Carbon (DLC) method.

However, when the imprint mold is manufactured by directly bonding a material having excellent mold release property to the surface of the imprint mold according to the above-described conventional method, the residue remains on the release-treated substrate or the bonding force between the mold and the release layer is repeatedly used. There is a problem that this difficult and high-density pattern implementation characteristics are degraded.

As described above, in the prior art, research and development has been focused on a method for directly forming a release layer on a mold, and by improving the properties of the imprint mold itself, it is possible to improve not only mold release properties but also various physical properties such as strength. The plan to do so has not been introduced yet.

Accordingly, in the present invention, as a result of extensive research to solve the above problems, it was possible to manufacture an imprint mold for a printed circuit board consisting of an electrolytic nickel plating layer filled with PTFE using an electrolytic nickel plating solution dispersed with PTFE powder, The present invention has been completed based on this.

Accordingly, an object of the present invention is to provide an imprint mold for a printed circuit board having excellent general properties such as high release property, high strength, high thermal conductivity, high durability, high heat resistance, chemical resistance, high water repellency, self-lubrication and corrosion resistance, and a manufacturing method thereof. It is.

Another object of the present invention is a printed circuit board imprint mold for manufacturing a printed circuit board with high productivity and high efficiency since the durability and excellent pattern realization characteristics are maintained for a long time even when repeated use in a large area printed circuit board imprint process and its manufacture To provide a method.

According to the present invention for achieving the above and other objects, a method of manufacturing an imprint mold for a printed circuit board using PTFE:

In the method of manufacturing an imprint mold for a printed circuit board having a structure corresponding to a plurality of vias and circuit patterns to be formed on the surface,

(a) preparing a master mold having a pattern of a structure including a plurality of vias and circuit patterns to be formed;

(b) forming a metal coating layer on the master mold on which the pattern of the structure is formed;

(c) preparing an electrolytic nickel plating solution in which a polytetrafluoroethylene (PTFE) powder is dispersed;

(d) contacting the electrolytic nickel plating solution on the master mold on which the metal coating layer is formed to form an electrolytic nickel plating layer filled with PTFE;

(e) separating the PTFE-filled electrolytic nickel plating layer from the master mold; And

(f) heat treating the separated nickel plating layer to decompose at least a portion of the PTFE filled in the plating layer;

Characterized in that it comprises a.

Here, it is preferable that the average particle diameter of the said PTFE powder is 10-100 nm.

It is preferable that content of PTFE in the said electrolytic nickel plating liquid is 5-50 mg / L.

The electrolytic nickel plating layer forming step is preferably carried out in the presence of a dispersant.

Here, the dispersant is a cationic dispersant or an anionic dispersant, preferably a compound having a phenyl group.

It is preferable that the usage-amount of the dispersing agent in the said electrolytic nickel plating liquid is 50-200 weight part with respect to 100 weight part of PTFE.

On the other hand, the electrolytic nickel plating solution manufacturing step may further include the step of sonicating the electrolytic nickel plating solution in which the PTFE powder is dispersed for 30 minutes to 1 hour.

The manufacturing of the electrolytic nickel plating solution may further include a step of separating and removing the PTFE that is bound by filtering the electrolytic nickel plating solution after the sonication step.

On the other hand, the heat treatment step of the separated nickel plating layer is preferably performed for 1 to 3 hours at a temperature of 300 ~ 400 ℃.

According to the present invention for achieving the above and other objects, an imprint mold for a printed circuit board using PTFE:

In the imprint mold for a printed circuit board having a structure corresponding to a plurality of vias and circuit patterns to be formed on the surface,

The mold is composed of a PTFE-filled electrolytic nickel plating layer, wherein at least a portion of the filled PTFE is decomposed through the heat treatment process of the mold to have a higher fluorine density on the inner surface than the central portion of the mold.

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

2A to 2E are views for explaining a manufacturing process of an imprint mold according to an embodiment of the present invention.

According to the present invention, first, a master mold 100 having a pattern of a structure including a plurality of vias and circuit patterns to be formed is prepared (see FIG. 2A).

In this case, the master mold 100 is formed to be opposite to the irregularities of the pattern of the nickel mold 200 for imprint to be obtained, the material of the master mold 100 is high in strength, such as silicon, diamond or quartz glass It is typical to make it.

Next, a metal coating layer 200 is formed on the master mold 100 on which the pattern of the structure is formed (see FIG. 2B).

The metal coating layer 200 is a conductive layer provided to perform electrolytic nickel plating, which is a subsequent process, and may be applied without particular limitation as long as it is a method known by those skilled in the art. For example, the coating may be performed by coating a metal such as Cu, Ti, or Cr through a vapor deposition method or a physical vapor deposition (PVD) method. The thickness of the metal coating layer 200 is not particularly limited, but 0.01 to 1㎛ is most suitable in terms of efficiency compared to the efficiency.

Next, an electrolytic nickel plating solution in which a polytetrafluoroethylene (PTFE) powder, also referred to as teflon, is dispersed is prepared.

According to one preferred embodiment of the present invention, the preparation of the electrolytic nickel plating solution is to put a nano-size PTFE powder in a Ni Watt bath and sonicated for 30 minutes to 1 hour in the presence of a dispersant to disperse the PTFE powder, then filtered It can be performed by separating and removing the aggregated PTFE.

Here, it is preferable that the average particle diameter of the said PTFE powder is 10-100 nm. If the average particle diameter of the PTFE powder is less than 10nm, it is not easy to manufacture, if it exceeds 100nm may affect the implementation of the pattern (~ 10㎛) of the printed circuit board.

It is preferable that content of PTFE in the said electrolytic nickel plating liquid is 5-50 mg / L. When the content of PTFE is less than 5 mg / L, the release property improvement is insignificant, and when it exceeds 50 mg / L, dispersion is not easy.

On the other hand, the dispersant may be a cationic dispersant or an anionic dispersant, more preferably as a dispersant having a phenyl group, for example, Benzalkonium Chloride (BKC), Sodium Dodecylbenzene Sulfonate (NaDDBS), TritonX (ACROS organics) Etc., but is not particularly limited thereto.

Here, it is preferable that the usage-amount of the dispersing agent in the said electrolytic nickel plating liquid is 50-200 weight part with respect to 100 weight part of PTFE. If the amount of the dispersant is less than 50 parts by weight, the PTFE powder may not be uniformly dispersed. If the amount of the dispersant is more than 200 parts by weight, the amount of the dispersant may be excessive, resulting in poor dispersion and adversely affect the electroplating process. .

Next, in the electrolytic nickel plating bath in which the PTFE powder 321 is dispersed as described above, the nickel electrode 311 is connected to the anode and the master mold 100 is connected to the cathode (see FIG. 3). The electrolytic nickel plating solution is contacted on the master mold 100 having the 200 formed thereon to form an electrolytic nickel plating layer 310 filled with PTFE 320 (see FIG. 2C).

Here, the electrolytic nickel plating process may be applied without particular limitation as long as it is a method known by those skilled in the art.

Next, the nickel mold 300 composed of the electrolytic nickel plating layer 310 filled with the PTFE 320 is separated from the master mold 100 (see FIG. 2D).

Finally, the separated nickel mold 300 is heat-treated to decompose at least a part of the PTFE 320 filled in the plating layer 310 to complete the nickel mold 300 having a higher fluorine density on the inner surface than the central portion. (See FIG. 2E).

Here, the heat treatment process of the separated nickel mold 300 is most suitable to decompose PTFE by performing a sufficient time between Ni and PTFE to be performed for 1 to 3 hours at a temperature of 300 to 400 ° C.

The nickel imprint mold according to the present invention prepared as described above has high fluorine density on the inner surface thereof, and thus shows hydrophobicity and shows good release characteristics. In addition, due to the properties of the nickel metal itself and the synergistic effect of filling the filler therein, excellent physical properties such as high strength, high thermal conductivity, high durability, high heat resistance, chemical resistance, high water repellency, self-lubrication and corrosion resistance Do.

In addition, due to such excellent characteristics, it exhibits excellent durability and high-density pattern implementation characteristics even when repeated use in a large area such as a printed circuit board compared to the nickel mold having a release agent layer formed on the mold surface through a conventional deposition method.

In addition, the mold itself is excellent in durability, high density, high reliability pattern implementation characteristics are maintained for a long time there is an advantage that can be produced a printed circuit board with high productivity and high efficiency.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited thereto.

Example 1

An aluminum layer having a thickness of 0.1 μm was formed on the silicon master mold on which the fine patterns were formed by the sputtering method.

Next, 15 mg / L of Teflon (Dupont) powder having an average particle diameter of about 50 nm and about 15 mg / L of BKC (Benzalkonium Chloride, ALDRICH) as a dispersant were added to Ni Watt 4L, an electrolytic nickel plating solution, and ultrasonic for about 30 minutes. After the treatment, the Teflon, which was not dispersed and separated by filtering, was separated and removed to prepare an electrolytic nickel plating solution in which Teflon was dispersed.

Next, using the electrolytic nickel plating apparatus as shown in FIG. 3, the electrolytic nickel plating solution was contacted for 60 to 120 minutes at a temperature of about 40 to 50 ° C. on the master mold on which the aluminum layer was formed to be filled with Teflon-filled electrolysis. A nickel plated layer was formed.

Next, the electrolytic nickel plated layer filled with the Teflon was separated from the master mold, and then heat-treated at a temperature of about 300 ° C. for about 2 hours to prepare a nickel mold for imprint according to the present invention.

Example 2

A titanium layer having a thickness of 0.1 μm was formed on the silicon master mold on which the fine patterns were formed by the sputtering method.

Next, 15 mg / L of Teflon (Dupont) powder having an average particle diameter of about 50 nm and about 15 mg / L of BKC (Benzalkonium Chloride, ALDRICH) as a dispersant were added to Ni Watt 4L, an electrolytic nickel plating solution, and ultrasonic for about 30 minutes. After the treatment, the Teflon, which was not dispersed and separated by filtering, was separated and removed to prepare an electrolytic nickel plating solution in which Teflon was dispersed.

Next, using the electrolytic nickel plating apparatus as shown in FIG. 3, the electrolytic nickel plating solution was contacted for 60 to 120 minutes at a temperature of about 40 to 50 ° C. on the master mold on which the aluminum layer was formed to be filled with Teflon-filled electrolysis. A nickel plated layer was formed.

Next, the electrolytic nickel plated layer filled with the Teflon was separated from the master mold, and then heat-treated at a temperature of about 350 ° C. for about 2 hours to prepare a nickel mold for imprint according to the present invention.

Example 3

An aluminum layer having a thickness of 0.1 μm was formed on the silicon master mold on which the fine patterns were formed by the sputtering method.

Next, 20 mg / L of Teflon (Dupont) powder having an average particle diameter of 50 nm and NaDDBS 30 mg / L as a dispersant were placed in Ni Watt 4L, which is an electrolytic nickel plating solution, sonicated for about 30 minutes, and then filtered and dispersed. Teflon was separated and removed to prepare an electrolytic nickel plating solution in which Teflon was dispersed.

Next, using the electrolytic nickel plating apparatus as shown in FIG. 3, the electrolytic nickel plating solution was contacted for 60 to 120 minutes at a temperature of about 40 to 50 ° C. on the master mold on which the aluminum layer was formed to be filled with Teflon-filled electrolysis. A nickel plated layer was formed.

Next, the electrolytic nickel plated layer filled with the Teflon was separated from the master mold, and then heat-treated at a temperature of about 300 ° C. for about 2 hours to prepare a nickel mold for imprint according to the present invention.

※ Physical property measurement ※

Evaluation of mold release properties, durability, and pattern implementation characteristics using the following method using the Teflon-filled nickel molds prepared in Examples 1 to 3 and a conventional nickel mold (Comparative Example 1) not filled with Teflon, respectively, were as follows. The results obtained therefrom are shown in Table 1 below.

(1) Evaluation method of release property: Confirmation of residue on the surface (microscope, SEM, EDS, mass measurement)

≧ surface observation through a microscope (× 5) (FIG. 4), surface observation through an SEM (Example 1: × 500, Examples 2-3 and Comparative Example 1: × 1000) (FIG. 5), surface via EDS Residual material analysis, residue identification through mold release before and after release

(2) Evaluation Method of Durability: Release Repeat Test

→ release repeatability measurement with the same mold (FIG. 6)

(3) Evaluation method of pattern implementation characteristics: SEM, 3D measuring machine

→ Transfer pattern confirmation through SEM (Fig. 5), pattern transfer confirmation through 3D measuring machine (Fig. 7)

Example 1 Example 2 Example 3 Comparative Example 1 Microscopic observation Good Good Good Bad 3D Measuring Machine Good Good Good Bad SEM Good Good Good Bad Mass measurement ¹⁾ 1.25mg 2.4mg 1.04 mg 48mg

¹⁾ Measurement of weight difference between mold before and after mold release

6A and 6B are photographs showing observations of changes in the mold surface during repeated use of an imprint mold manufactured according to Example 1 and Comparative Example 1 of the present invention in a printed circuit board imprint process, respectively. In the case of the mold according to Example 1 of the present invention, there was no change in repeated use, but in the case of the mold according to Comparative Example 1, it was confirmed that a phenomenon in which the film adhered to the mold occurred after two uses.

7A to 7D are diagrams illustrating three-dimensional measurement values of an imprint mold (FIGS. 7A and 7B) manufactured according to Example 1 of the present invention and a film pattern (FIGS. 7C and 7D) formed through an imprint process using the same. Referring to this, the pattern implementation characteristics of the imprint mold manufactured according to the first embodiment of the present invention are as follows.

FIG. 7A is a thickness measurement of a mold measured using a laser profiler, which shows that the design of the master mold (13 to 17 μm) is slightly different but uniformly manufactured.

Figure 7b is a 3D view of the shape of the mold using a laser, showing that the pattern of the mold is produced uniformly.

7C is a thickness measurement of a film pattern actually formed through an imprint process using the imprint mold, measured using a laser profiler, and shows a slight difference from the measurement of the mold (11 μm), but the pattern is well transferred to the insulating film. It can be seen that (depth of about 10㎛ pattern is formed).

FIG. 7D illustrates the shape of the film pattern actually formed through the imprint process using the imprint mold using a laser in 3D. It can be seen that the transfer pattern is uniformly formed.

8A to 8D illustrate three-dimensional measurement values of an imprint mold (FIGS. 8A and 8B) manufactured according to Comparative Example 1 of the present invention and a film pattern (FIGS. 8C and 8D) formed through an imprint process using the same. Referring to this, the pattern implementation characteristics of the imprint mold manufactured according to Comparative Example 1 are as follows.

FIG. 8A is a thickness measurement of a mold measured using a laser profiler, and it can be seen that the design of the master mold (13 to 17 μm) and a large difference (˜9 μm) are produced unevenly.

8B is a 3D view of the shape of the mold using a laser, showing that the pattern of the mold is produced unevenly (the color is uneven).

FIG. 8C is a thickness measurement value of a film pattern actually formed through an imprint process using the imprint mold measured using a laser profiler, and shows a large difference from the measurement value of the mold (11 μm), and a pattern is well formed on an insulating film. It can be seen that it is not (transferred about 6㎛).

FIG. 8D illustrates the shape of the film pattern actually formed through the imprint process using the imprint mold using a laser in 3D, and it can be seen that the transfer pattern is not uniform (color is not uniform).

From the result data as described above, it can be seen that the imprint mold composed of the electrolytic nickel plating layer filled with PTFE according to the present invention has superior releasability, durability, and pattern realization characteristics as compared with a conventional nickel mold without PTFE filled. there was.

Although the present invention has been described in detail with reference to specific examples, this is for explaining the present invention in detail, and the imprint mold for a printed circuit board using the PTFE according to the present invention and a manufacturing method thereof are not limited thereto. It is apparent that modifications and improvements are possible by those skilled in the art within the technical idea.

As described above, according to the present invention, an imprint nickel mold made of an electrolytic nickel plating layer filled with PTFE is prepared using an electrolytic nickel plating solution in which PTFE powder is dispersed, and then, among the PTFE filled in the mold through a heat treatment process. Pyrolysis of at least a portion thereof provides a nickel imprint mold for a printed circuit board having a high density of fluorine disposed on an inner surface thereof.

The printed circuit board nickel imprint mold has excellent release characteristics according to the hydrophobic characteristics exhibited by high density fluorine on the inner surface, and also has high strength and high temperature due to the synergistic effect of the nickel metal itself and the filling of the filler therein. Excellent physical properties such as conductivity, high durability, high heat resistance, chemical resistance, high water repellency, self-lubrication and corrosion resistance.

In addition, due to such excellent physical properties, there is an advantage that a high density pattern can be realized even when repeated use in a large area such as a printed circuit board compared to the nickel mold having a release agent layer formed through a conventional deposition method.

In addition, the mold itself is excellent in durability, high density, high reliability pattern implementation characteristics are maintained for a long time there is an advantage that can be produced a printed circuit board with high productivity and high efficiency.

Accordingly, unlike the case where the imprint nickel mold of the present invention is applied to a conventional nanoimprint method, the size of a structure corresponding to a plurality of vias and patterns to be formed has a micron order (for example, line / space≤10㎛ / 10㎛, Microvia≤30㎛) and it has excellent release characteristics and durability even when applied to a printed circuit board that requires application to a large area, and the mold release property is maintained for a long time Dramatically reduce release processing time and costs.

All modifications and variations of the present invention fall within the scope of the present invention, and the specific scope of protection of the present invention will be apparent from the appended claims.

Claims (11)

In the method of manufacturing an imprint mold for a printed circuit board having a structure corresponding to a plurality of vias and circuit patterns to be formed on the surface, (a) preparing a master mold having a pattern of a structure including a plurality of vias and circuit patterns to be formed; (b) forming a metal coating layer on the master mold on which the pattern of the structure is formed; (c) preparing an electrolytic nickel plating solution in which a polytetrafluoroethylene (PTFE) powder is dispersed; (d) contacting the electrolytic nickel plating solution on the master mold on which the metal coating layer is formed to form an electrolytic nickel plating layer filled with PTFE; (e) separating the PTFE-filled electrolytic nickel plating layer from the master mold; And (f) heat treating the separated nickel plating layer to decompose at least a portion of the PTFE filled in the plating layer; Method of manufacturing an imprint mold for a printed circuit board using PTFE comprising a. The method of manufacturing an imprint mold for a printed circuit board using PTFE according to claim 1, wherein the average particle diameter of the PTFE powder is 10 to 100 nm. The method of manufacturing an imprint mold for a printed circuit board using PTFE according to claim 1, wherein the content of PTFE in the electrolytic nickel plating solution is 5 to 50 mg / L. The method of claim 1, wherein the electrolytic nickel plating layer forming step is performed in the presence of a dispersant. The method of claim 4, wherein the dispersing agent is a cationic dispersing agent or an anionic dispersing agent. The method of claim 5, wherein the dispersing agent is a compound having a phenyl group. The method of manufacturing an imprint mold for a printed circuit board using PTFE according to claim 4, wherein the amount of the dispersant in the electrolytic nickel plating solution is 50 to 200 parts by weight based on 100 parts by weight of PTFE. The imprint of claim 1, wherein the manufacturing of the electrolytic nickel plating solution further comprises ultrasonicating the electrolytic nickel plating solution in which the PTFE powder is dispersed for 30 minutes to 1 hour. Method for producing a mold. The method of claim 8, wherein the electrolytic nickel plating solution manufacturing step further comprises the step of separating and removing the PTFE bound by filtering the electrolytic nickel plating solution after the ultrasonic treatment step using a PTFE printed circuit board imprint mold Manufacturing method. The method of claim 1, wherein the heat treatment of the separated nickel plating layer is performed at a temperature of 300 to 400 ° C. for 1 to 3 hours. In the imprint mold for a printed circuit board having a structure corresponding to a plurality of vias and circuit patterns to be formed on the surface, Wherein the mold is made of PTFE-filled electrolytic nickel plating layer, wherein at least a portion of the filled PTFE is decomposed through the heat treatment process of the mold has a higher fluorine density on the inner surface than the central portion of the mold Imprint mold for printed circuit board using.

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