JP2022067371A - Transfer mold and wiring formation method - Google Patents

Abstract

To provide a transfer mold and a wiring forming method using the transfer mold in which an excess conductive member on the surface of the transfer mold can be easily and cleanly scraped off, and the residue of the conductive member and the gouging of the conductive member in the recess are less likely to occur.SOLUTION: In a transfer mold used when a conductive member 2 is transferred to the surface of a substrate 1 to form a wiring portion 3 on the surface of the substrate 1, a recess 4a having a predetermined pattern for transferring and forming the wiring portion 3 is formed, and a fluororesin layer 6 is provided on the substrate polymerization surface 4b which is a surface on which the recess 4a is formed and which is a surface to be overlapped with the surface of the substrate 1 when the conductive member 2 is transferred to the substrate 1.SELECTED DRAWING: Figure 3

Description

Application for application of Article 30, Paragraph 2 of the Patent Act (1) March 4, 2020 "The International Microlectronics Association" sponsored by "The Internet Technology Association" held at "WekoPa Rest & Conference Center" (IMS) Published (announced) at "and Exhibition on DEVICE PACKAGING" (2) September 28-October 23, 2020 "Surface Convention Technology Association (SMTA)" sponsored conference "SMTAIn" held on the Internet (Virtual) Public (announcement)

The present invention relates to a transfer type and a wiring forming method using this transfer type.

Wiring formation using conductive paste can be performed at a lower temperature than conventional wiring formation using copper wiring or metal such as solder, so wiring formation on film such as plastic, which was not possible until now, can be performed. Chip mounting is possible.

Conventionally, wiring formation using this conductive paste is generally performed by using a printing method. However, in the printing method, there is a limit to the minimum line width of the wiring that can be formed. For example, in a typical screen printing, the wiring printing having a width of about 30 μm is the limit. In addition, although a paste or ink-like conductive member is used in the printing method, it does not cure immediately after printing on the substrate. Therefore, when thick wiring (wiring with a high aspect ratio) is formed, the wiring bleeds and the dimensional accuracy is correct. In addition, shape sagging occurs due to the fluidity of a certain viscosity of the paste or ink-like conductive member. Therefore, at present, the upper limit of the aspect ratio of the wiring that can be formed by the printing method is about 0.5 at most.

On the other hand, in the transfer wiring formation method (imprint method) using a transfer type, wiring miniaturization up to nano-level size is possible, and since the conductive paste is cured and transferred, wiring formation with an aspect ratio of 1 or more is formed. Is also possible.

Regarding the transfer wiring forming method using this transfer type, the present applicant has proposed a method for manufacturing a substrate having a conductive portion disclosed in JP-A-2016-58664 (hereinafter referred to as a conventional example).

In this conventional example, a conductive member (conductive paste) is provided in the recess of a transfer type (denoted as a printing plate in Japanese Patent Laid-Open No. 2016-58664) having a recess formed in a pattern similar to the wiring pattern formed on the substrate. By superimposing the transfer mold filled with the concave portion of the transfer mold on the substrate and pressing it against the substrate, the conductive member filled in the concave portion of the transfer mold is transferred to the substrate and a predetermined pattern is applied on the substrate. It forms the wiring of.

In this transfer wiring forming method, when the transfer type recess is filled with the conductive member, it protrudes from the recess by using a scraper called a squeegee so that the conductive member is filled only in the recess. Excessive conductive members on the surface of the transfer type other than the conductive members and recesses are removed.

Japanese Unexamined Patent Publication No. 2016-58664

However, conventionally, after the scraping removal treatment of the excess conductive member using this scraper, as shown in FIG. 6, the excess conductive member is not properly removed and the remaining conductive member is generated. There may be a problem that the conductive member in the recess is scooped out, and when the remaining conductive member is left, the remaining conductive member is transferred to the substrate together with the conductive member filled in the recess to form a transfer. There is a risk of short-circuiting the wiring that has been made, and if gouge occurs, the conductive member will not be transferred properly to the substrate, or the adhesion of the transferred wiring to the substrate will decrease and the wiring will come off. In addition, if the gouge is large, the wiring resistance of the transfer-formed wiring may increase or disconnection may occur.

The present invention has been made in view of the current situation, and the excess conductive member on the surface of the transfer mold can be easily and cleanly scraped off, and the residue of the conductive member and the conductivity in the recess can be removed. A transfer type in which members are less likely to be gouged and a wiring forming method using this transfer type are provided.

The gist of the present invention will be described with reference to the accompanying drawings.

A transfer type used when the conductive member 2 is transferred to the surface of the substrate 1 to form the wiring portion 3 on the surface of the substrate 1, and the recess 4a having a predetermined pattern for transferring and forming the wiring portion 3 is provided. A fluororesin layer 6 is provided on the substrate polymerization surface 4b which is formed and is superposed on the surface of the substrate 1 when the conductive member 2 is transferred to the substrate 1 on the surface on which the recess 4a is formed. It relates to a transfer type characterized by being.

Further, in the transfer type according to claim 1, the transfer type is characterized in that the fluororesin layer 6 is also provided on the inner surface of the recess 4a.

Further, in the transfer type according to any one of claims 1 and 2, the fluororesin layer 6 relates to a transfer type characterized by having ultraviolet resistance.

Further, in the transfer type according to any one of claims 1 to 3, the fluororesin layer 6 is related to a transfer type characterized in that the thickness is set to 10 nm or less.

Further, the concave portion 4a of the transfer mold 4 in which the concave portion 4a having a predetermined pattern is formed is filled with the conductive member 2, and the transfer mold 4 filled with the conductive member 2 is superposed on the surface of the substrate 1 to obtain the said. A method of transferring the conductive member 2 to the surface of the substrate 1 to form a wiring portion 3 on the surface of the substrate 1 by the conductive member 2, the substrate overlapping surface 4b to be overlapped with the substrate 1 and the substrate 1 The transfer type 4 in which the fluororesin layer 6 is provided on the inner surface of the recess 4a formed on the substrate polymerization surface 4b is prepared, and subsequently, on the substrate polymerization surface 4b provided with the fluoropolymer layer 6 and the above. The conductive member 2 is supplied to the inner surface of the recess 4a, and then the conductive member 2 on the substrate overlapping surface 4b is scraped off by an appropriate means to fill the recess 4a with the conductive member 2. It relates to a characteristic wiring forming method.

Further, in the wiring forming method according to claim 5, the fluororesin layer 6 relates to a wiring forming method characterized by having ultraviolet resistance.

Further, in the wiring forming method according to any one of claims 5 and 6, the appropriate means is a scraper 5, and the scraper 5 is covered with a fluororesin film 7. It relates to the wiring forming method.

Further, in the wiring forming method according to claim 7, the fluororesin film 7 relates to a wiring forming method characterized by being a polytetrafluoroethylene film.

Since the present invention is configured as described above, the excess conductive member on the surface of the transfer mold can be easily and cleanly scraped off, and the residue of the conductive member and the gouge of the conductive member in the recess can be removed. It is a transfer type that is unlikely to occur and a wiring forming method using this transfer type.

It is explanatory normal sectional drawing which shows the transfer type of this Example. It is explanatory normal sectional drawing which shows the main part of the scraping tool of this Example. It is sectional drawing of the wiring formation method of this Example. It is a process flow diagram of the wiring formation method of this Example. It is a photograph which shows the state of the transfer type (state of the substrate polymerization surface) after the conductive member filling process in the wiring formation method of this Example. It is a photograph showing the state of the transfer type (state of the substrate polymerization surface) after the conductive member filling process in the conventional wiring forming method (a is the rest of the conductive member, and b is the gouge).

An embodiment of the present invention which is considered to be suitable will be briefly described by showing the operation of the present invention based on the drawings.

In the transfer type 4 of the present invention, the fluororesin layer 6 is provided on the substrate polymerization surface 4b which is overlapped with the surface of the substrate 1 when the conductive member 2 is transferred to the substrate 1.

For example, when the transfer mold 4 is made of a material containing a silicone resin as a main component, when the wettability of the conductive member 2 to the silicone resin and the wettability to the fluororesin are compared, the wettability to the fluororesin is higher. Since it is low, by providing the fluororesin layer 6 on the substrate polymerization surface 4b, the wettability of the conductive member 2 with respect to the substrate polymerization surface 4b is lowered (the contact angle of the conductive member 2 with respect to the substrate polymerization surface 4b is increased). ..

As a result, the releasability of the conductive member 2 with respect to the substrate polymerization surface 4b is improved. For example, when the conductive member 2 on the substrate polymerization surface 4b is scraped off, it becomes easy to scrape off and the residue of the conductive member is less likely to occur. Become.

Further, by improving the scraping property of the conductive member 2, for example, the scooping of the conductive member 2 in the recess 4a is suppressed during the scraping process by the scraping tool 5, and the scooping is less likely to occur.

As described above, according to the present invention, the excess conductive member 2 on the substrate polymerization surface 4b can be easily and appropriately scraped off, and the remainder of the conductive member and the gouge of the conductive member 2 in the recess 4 can be obtained. It is a transfer type that is unlikely to occur and a wiring forming method using this transfer type.

Specific examples of the present invention will be described with reference to the drawings.

In this embodiment, the conductive member 2 is transferred to the surface of the substrate 1 to form the wiring portion 3 on the surface of the substrate 1, that is, the wiring portion 3 is transferred to the substrate 1 by the imprint method. Transfer type 4 to be used.

Hereinafter, the transfer type 4 of this example will be described in detail.

The transfer mold 4 of this embodiment is a wiring portion obtained by dropping a resin material onto a master plate on which a convex portion having a predetermined pattern is formed, pressurizing it with a support substrate, molding it, and then performing a curing treatment. It is generally called a replica mold in which the recess 4a of the predetermined pattern for transferring and forming the 3 is formed.

Specifically, the transfer type 4 of this example is made of a silicone resin obtained by curing a resin material obtained by mixing a curing agent with a main agent containing a silicone-based polymer compound as a main component, and is generally soft. It is called a soft replica mold.

Further, although not shown, the recess 4a formed in the transfer mold 4 has a tapered shape (when superposed on the substrate 1) so that the wiring portion 3 transferred and formed on the substrate 1 has a forward tapered shape. It is formed in a forward tapered shape).

Further, as shown in FIG. 1, the transfer type 4 of the present embodiment has an inner surface of the recess 4a and a surface on which the recess 4a is formed, and is used on the surface of the substrate 1 when the conductive member 2 is transferred to the substrate 1. The fluororesin layer 6 is provided on the substrate polymerization surface 4b, which is also the surface to be overlapped.

In this embodiment, the fluororesin layer 6 is a single molecular layer (monomolecular layer), and the thickness is set to 10 nm or less (about several nm).

Further, in this embodiment, in the wiring forming method using the transfer type 4 described later, ultraviolet irradiation is performed when the conductive member 2 is cured, so that the fluororesin layer 6 having ultraviolet resistance is provided. Specifically, the fluororesin layer 6 of this embodiment is formed by using Fluorosurf FG-5080 (manufactured by Fluorotechnology).

When not irradiating with ultraviolet rays or when using it for wiring formation for digital circuits where the insulation between wirings is not so high, for example, Fluorosurf FG-5084 (manufactured by Fluorotechnology), Garden Surf AZ-1001T03 (Harves). The fluororesin layer 6 formed by using (manufactured by Harves) or Dura Surf (manufactured by Harves) may be used.

Further, the means for providing the fluororesin layer 6 on the transfer mold 4 may be appropriate, and the fluororesin layer 6 of this embodiment is coated by using a spin coater. Specifically, the above Fluorosurf FG-5080 (manufactured by Fluoro Technology Co., Ltd.) is applied by a spin coater, dried at room temperature, then applied again and dried at room temperature.

The effects of the transcription type of this example configured as described above will be described below.

In terms of the wettability of the conductive member 2 with respect to the silicone resin and the wettability with respect to the fluororesin, the wettability with respect to the fluororesin is lower. Since the fluororesin layer 6 is provided in 4b, the conductive member 2 supplied to the transfer mold 4 does not come into direct contact with the substrate polymerization surface 4b of the transfer mold 4, but comes into contact with the fluororesin layer 6. Compared with the case where the fluororesin layer 6 is not provided, that is, in the case of directly contacting the substrate polymerization surface 4b of the silicone resin, the wettability of the conductive member 2 with respect to the substrate polymerization surface 4b is lowered (the substrate polymerization surface of the conductive member 2). The contact angle with respect to 4b (fluororesin layer 6) is increased).

As a result, in the transfer type 4 of the present embodiment, the releasability of the conductive member 2 with respect to the substrate polymerization surface 4b is improved, and when the conductive member 2 on the substrate polymerization surface 4b is scraped off, it becomes easy to scrape off. As shown in 5, the residue of the conductive member is less likely to occur on the substrate polymerization surface 4b after the conductive member filling process, and the scraping property of the conductive member 2 is improved, so that the scraping tool is used during the scraping process. The pressure of pressing the 5 against the substrate polymerization surface 4b can be reduced, and the scooping of the conductive member 2 in the recess 4a by the scraper 5 is suppressed, and the scooping is less likely to occur.

Next, a wiring forming method using the transfer type 4 of this embodiment will be described.

In the wiring forming method of this embodiment, as shown in FIGS. 3A to 3E, the concave portion 4 of the transfer mold 4 is filled with the conductive member 2, and the transfer mold 4 is filled with the conductive member 2. Is superposed on the surface of the substrate 1 and the conductive member 2 cured in the recess 4a is transferred to the surface of the substrate 1 to form a wiring portion 3 on the surface of the substrate 1 by the conductive member 2. A method, that is, an imprint wiring forming method (imprint method) in which a wiring portion 3 is transferred and formed on a substrate 1 by using a transfer type 4.

Specifically, as shown in FIG. 4, a step of filling the conductive member 2 in the recess 4a of the transfer mold 4 and a transfer mold 4 filled with the conductive member 2 are superposed on the substrate 1. The transfer type superimposition processing step of matching, the conductive member curing process of curing the conductive member 2 filled in the recess 4a of the transfer mold 4, and the conductive member 2 cured in the recess 4a of the transfer mold 4. It has a conductive member transfer processing step of transferring to the substrate 1 to form a wiring portion 3 having a predetermined pattern on the substrate 1, and the processing is performed in this order.

In this embodiment, a case where an active ray-curable resin-containing conductive paste in which the active ray-curable resin is contained in the conductive paste is used as the conductive member 2 will be described.

In the conductive member filling processing step, the transfer mold 4 is set so that the opening of the recess 4a faces upward, the conductive member 2 is filled in the recess 4a from above, and then the transfer mold 4 overflows from the surface or the recess 4a. This is a step of scraping off the protruding conductive member 2 using a scraper 5 (squeegee) and filling the recess 4a with the conductive member 2.

Specifically, the conductive member 2 to be filled in the recess 4a of the transfer mold 4 includes Ag paste (including nanopaste), Cu paste (including nanopaste), Au paste (including nanopaste), and Pt paste (including nanopaste). ), Pd paste (including nanopaste), Ru paste (including nanopaste), C paste (including nanopaste) with UV curable resin-containing conductive paste containing UV curable resin. Therefore, in this embodiment, an ultraviolet curable resin-containing Ag paste containing an ultraviolet curable resin is used.

Further, the conductive paste is a conductive paste in which the average particle diameter is set to 1/5 to 1/10 of the minimum line width of the wiring portion 3 formed on the substrate 1. That is, for example, when forming a wiring pattern having a minimum L / S (line & space) = 5 μm / 5 μm, the average particle diameter is set to 0.5 μm to 1.0 μm.

Further, in the conductive member 2 of this embodiment, the volume ratio of the conductive base and the ultraviolet curable resin is set to 6: 4 to 8: 2.

In this conductive member filling treatment step, in this embodiment, as described above, the transfer type 4 having the fluoropolymer layer 6 provided on the substrate polymerization surface 4b to be overlapped with the substrate 1 is used, and the conductive member 2 is scraped off. The scraping tool 5 (squeegee) is coated with a fluororesin film 7 (specifically, a polytetrafluoroethylene film) on the contact surface to be brought into contact with the substrate polymerization surface 4b of the transfer type 4 as shown in FIG. The scraper 5 that has been used is used.

The conventional scraping tool is made of SUS and is formed by cutting with a laser, and the laser cutting surface is a scraping surface (a contact surface that abuts on a transfer type substrate polymerization surface). Therefore, the scraped surface may have irregularities, and the presence of the irregularities may cause residual conductive members (residual scraping) in a streak shape along the scraping direction.

In this embodiment, as described above, the contact surface (scraping surface) of the scraper 5 is covered with the fluororesin film 7 (polytetrafluoroethylene film), and the contact surface is flattened. The contact surface uniformly abuts on the substrate polymerization surface 4b and can be uniformly scraped off without leaving the conductive member 2 on the substrate polymerization surface 4b.

Moreover, since the scraper 5 used in this embodiment is covered with the fluororesin film 7 (polytetrafluoroethylene film) as described above, the wettability to the conductive member 2 is lowered and the substrate polymerization surface 4b is covered. The slipperiness is improved and smooth scraping operation can be performed.

As described above, in the conductive member filling treatment step of this embodiment, the transfer type 4 in which the fluoropolymer layer 6 is provided on the substrate polymerization surface 4b to be overlapped with the substrate 1 is used, and the substrate polymerization surface 4b of the transfer type 4 is used. Using a scraper 5 whose contact surface to be abutted is covered with a fluororesin film 7 (polytetrafluoroethylene film), the releasability of the conductive member 2 with respect to the transfer type 4 (substrate polymerization surface 4b) can be determined. In addition to improving the scraping performance, the scraping performance of the scraping tool 5 is improved, and the excess conductive member 2 on the substrate polymerization surface 4b is easily and appropriately scraped off to remove the residue of the conductive member and the inside of the recess 4. The conductive member 2 of the above is prevented from being gouged.

Further, the transfer type superposition processing step is a step of superimposing the transfer type 4 in which the concave portion 4a is filled with the conductive member 2 on the substrate 1 and pressing the transfer type 4 against the substrate 1 by pressurization.

Further, the conductive member curing treatment step is a step of curing the conductive member 2 filled in the recess 4a of the transfer mold 4 to improve the releasability of the conductive member 2 with respect to the transfer mold 4.

As described above, in this embodiment, since the active light curable resin-containing conductive paste, specifically, the Ag paste containing the ultraviolet curable resin is used as the conductive member 2, this conductive member curing treatment is performed. In the process, the conductive member 2 is cured by irradiation with active light, specifically, ultraviolet rays.

Specifically, ultraviolet rays are irradiated from the bottom side of the recess 4a of the transfer mold 4 to cure the contact interface portion of the conductive member 2 filled in the recess 4a of the transfer mold 4 with the inner surface of the recess.

By curing the conductive member 2 by irradiation with ultraviolet rays as in this embodiment, the processing time can be significantly shortened as compared with the case where the conductive member 2 is cured by heating.

The conductive member curing treatment step may be performed before the transfer mold 4 is superposed on the substrate 1, that is, before the transfer mold superposition treatment step.

Further, in this embodiment, the transfer mold 4 is also irradiated with ultraviolet rays in this conductive member curing treatment step, but the fluororesin layer 6 provided on the substrate polymerization surface 4b of the transfer mold 4 of this embodiment is Since it has ultraviolet resistance, deterioration of the fluororesin layer 6 due to ultraviolet irradiation in this conductive member curing treatment step is prevented, and the above-mentioned effects are exhibited in the long term.

Further, in the conductive member transfer processing step, the transfer mold 4 overlapped with the substrate 1 is separated from the substrate 1, the conductive member 2 in the recess 4a of the transfer mold 4 is transferred to the substrate 1, and the transfer mold 4 is predetermined on the substrate 1. This is a step of forming the wiring portion 3 of the pattern.

In this embodiment, since the fluororesin layer 6 is also provided on the inner surface of the recess 4a of the transfer mold 4, the releasability of the conductive member 2 from the transfer mold 4 due to the synergistic effect of the curing treatment and the fluororesin layer 6 Is improved, and smooth transfer of the conductive member 2 is performed.

The wiring forming method of the present embodiment processed in the above steps improves the workability of the scraping work of the conductive member 2 in the conductive member filling processing step, and also improves the workability of the conductive member 2 residue and the conductivity in the recess 4. This is an epoch-making wiring forming method that suppresses the occurrence of gouging of the sex member 2 and exerts the effect of improving the yield.

The present invention is not limited to the present embodiment, and the specific configuration of each constituent requirement can be appropriately designed.

1 Substrate 2 Conductive member 3 Wiring part 4 Transfer type 4a Recess 4b Substrate polymerization surface 5 Scraper 6 Fluororesin layer 7 Fluororesin film

Claims (8)

It is a transfer type used when a conductive member is transferred to the surface of a substrate to form a wiring portion on the surface of the substrate, and a recess having a predetermined pattern for transferring and forming the wiring portion is formed. A transfer type characterized in that a fluororesin layer is provided on a substrate polymerization surface to be superposed on the surface of the substrate when the conductive member is transferred to the substrate as a surface on which a recess is formed. The transfer type according to claim 1, wherein the fluororesin layer is also provided on the inner surface of the recess. The transfer type according to any one of claims 1 and 2, wherein the fluororesin layer has ultraviolet resistance. The transfer type according to any one of claims 1 to 3, wherein the fluororesin layer has a thickness of 10 nm or less. A conductive member is filled in the concave portion of the transfer mold in which a concave portion having a predetermined pattern is formed, the transfer mold filled with the conductive member is superposed on the surface of the substrate, and the conductive member is placed on the surface of the substrate. It is a method of transferring and forming a wiring portion on the surface of the substrate by the conductive member, and a fluororesin layer is formed on the inner surface of the substrate polymerization surface to be overlapped with the substrate and the recess formed on the substrate polymerization surface. The transfer mold provided is prepared, and then the conductive member is supplied on the substrate polymerization surface on which the fluoropolymer is provided and on the inner surface of the recess, and subsequently, the said on the substrate polymerization surface. A wiring forming method comprising scraping a conductive member by an appropriate means and filling the concave portion with the conductive member. The wiring forming method according to claim 5, wherein the fluororesin layer has ultraviolet resistance. The wiring forming method according to any one of claims 5 and 6, wherein the appropriate means is a scraper, and the scraping tool is covered with a fluororesin film. The wiring forming method according to claim 7, wherein the fluororesin film is a polytetrafluoroethylene film.

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