Conductive structure and method of making the same

Abstract

The application discloses a conductive structure and a manufacturing method thereof, and relates to the technical field of electronic circuit manufacturing; the conductive structure comprises the following steps: providing a base material; the base material has a bearing part with a plurality of micropore structures; conductive paste in direct contact with the micropore structures is applied on the surface of the bearing part of the base material, and part of the organic adhesive in the conductive paste is infiltrated into the micropore structures, so that the conductive paste with a reduced proportion of organic adhesive is obtained on the surface of the bearing part; the conductive paste and the micropore structures satisfy the following relationship: the particle size of the conductive particles in the conductive paste is greater than the pore size of the micropore structures; the conductive paste is subjected to solidification treatment, so that the conductive trace on the surface of the bearing part is obtained. The application transfers part of the organic adhesive in the conductive paste by the micropore structures on the base material, so that the proportion of the organic adhesive in the conductive paste on the surface of the base material is reduced, the proportion of the conductive particles in the conductive paste on the surface of the base material is increased, and the conductive performance of the conductive trace after solidification is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of electronic circuits, and in particular relates to a conductive structure and a manufacturing method thereof. Background Art

[0002] With technological advancements and growing environmental awareness and requirements, additive manufacturing is increasingly being used in traditional PCBs and flexible printed circuits (FPCs) to reduce waste, shorten processes, and lower costs. Additive manufacturing typically involves printing or printing conductive traces onto a substrate using a conductive paste. The traces are then dried at low temperatures to achieve the desired conductivity and adhesion characteristics. However, these traces often exhibit poor conductivity. Summary of the Invention

[0003] In view of this, an object of the present invention is to provide a method for manufacturing a conductive structure to solve the problem of poor conductivity of conductive lines formed by using conductive paste in the prior art.

[0004] In some illustrative embodiments, the method for manufacturing the conductive structure includes: providing a substrate; the substrate has a supporting portion with a plurality of microporous structures; applying a conductive paste on the surface of the supporting portion of the substrate so as to be in direct contact with the microporous structure, and allowing part of the organic adhesive in the conductive paste to penetrate into the microporous structure to obtain a conductive paste located on the surface of the supporting portion and with a reduced proportion of organic adhesive; wherein the conductive paste and the microporous structure satisfy the following relationship: the particle size of the conductive particles in the conductive paste is larger than the pore size of the microporous structure; and curing the conductive paste to obtain conductive traces located on the surface of the supporting portion.

[0005] In some optional embodiments, before applying the conductive paste, the method further includes: forming the microporous structure on the substrate by mechanical and / or laser etching.

[0006] In some optional embodiments, after obtaining the conductive trace, the method further includes: depositing at least one metal reinforcement layer on the conductive trace.

[0007] In some optional embodiments, the conductive particles in the conductive paste include one or more of flake-shaped, branch-shaped, and needle-shaped particles.

[0008] In some optional embodiments, the microporous structure is provided with a notch close to the port of the conductive paste.

[0009] In some alternative embodiments, during the solidification process of the conductive paste, the organic adhesive in the micro-hole structure is also solidified to form a reinforcing part integrated with the conductive trace on the surface of the bearing part.

[0010] In some alternative embodiments, the substrate is made of a material that can infiltrate the organic adhesive.

[0011] Another object of the present application is to provide a conductive structure to solve the technical problems in the prior art.

[0012] In some illustrative embodiments, the conductive structure comprises: a substrate having a bearing part with a plurality of micro-hole structures; a conductive trace formed on the bearing part; wherein the conductive trace is formed by solidifying a conductive paste, and before solidification, part of the organic adhesive in the conductive paste infiltrates into the micro-hole structure; wherein the conductive paste and the micro-hole structure satisfy the following relationship: the particle size of the conductive particles in the conductive paste is greater than the pore size of the micro-hole structure.

[0013] In some alternative embodiments, the conductive structure further comprises: at least one metal reinforcing layer formed on the surface of the conductive trace.

[0014] In some alternative embodiments, the conductive structure further comprises: a reinforcing part located in the micro-hole structure and integrated with the conductive trace on the surface of the bearing part.

[0015] Compared with the prior art, the present application has the following advantages:

[0016] The present application uses the micro-hole structure on the substrate to transfer part of the organic adhesive in the conductive paste, thereby reducing the proportion of organic adhesive in the conductive paste on the surface of the substrate, increasing the proportion of conductive particles in the conductive paste on the surface of the substrate, and improving the conductive performance of the conductive trace after solidification. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is an example of a flowchart of a method for manufacturing a conductive structure in an embodiment of the present application;

[0018] Figure 2 is an example of a process for manufacturing a conductive structure in an embodiment of the present application;

[0019] Figure 3 is an example of a micro-hole structure of a substrate in an embodiment of the present application;

[0020] Figure 4 is an example of a flowchart of a method for manufacturing a conductive structure in an embodiment of the present application;

[0021] Figure 5is a structural example of the conductive structure in the embodiments of the present application;

[0022] Figure 6 is a flow example three of the manufacturing method of the conductive structure in the embodiments of the present application. DETAILED DESCRIPTION

[0023] The following description and drawings are illustrative of the specific embodiments of the present application and are not intended to be limiting. Other embodiments can include structural, logical, electrical, process, and other changes. The embodiments are representative only. Individual components and functions are optional unless explicitly required, and the order of operations can vary. Portions and features of some embodiments can be included in, or substituted for, those of other embodiments. The scope of embodiments of the present application encompasses the entire scope of the claims, and all available equivalents of the claims. In this document, these embodiments of the present application can be referred to in individual or collective form using the term "application," which is merely for convenience and is not intended to limit the application's scope to a single application or inventive concept if more than one is, in fact, disclosed.

[0024] It should be noted that the technical features in the embodiments of the present application can be combined with each other without conflict.

[0025] The embodiments of the present application disclose a manufacturing method of a conductive structure, specifically, with reference to Figures 1-2 , Figure 1 is a flow example one of the manufacturing method of the conductive structure in the embodiments of the present application; Figure 2 is a process example of the manufacturing method of the conductive structure in the embodiments of the present application. The manufacturing method of the conductive structure comprises:

[0026] Step S11, providing a substrate 10;

[0027] The substrate 10 has a bearing part with a plurality of micropore structures 101;

[0028] Step S12, applying a conductive paste 20 in direct contact with the micropore structures 101 on the surface of the bearing part of the substrate 10, and making part of the organic adhesive 21 in the conductive paste 20 infiltrate the micropore structures 101, to obtain the conductive paste 20' with reduced proportion of organic adhesive 21 on the surface of the bearing part;

[0029] The conductive paste 20(20') and the micropore structures 101 satisfy the following relationship: the particle size of the conductive particles 22 in the conductive paste is greater than the pore size of the micropore structures 101;

[0030] Step S13, curing treatment is performed on the conductive paste 20', to obtain a conductive trace 30 (film-forming substance 31 and conductive particles 22) on the surface of the carrier portion.

[0031] The present application transfers part of the organic binder in the conductive paste by the micro-porous structure on the substrate, thereby reducing the proportion of the organic binder in the conductive paste on the surface of the substrate, increasing the proportion of the conductive particles in the conductive paste on the surface of the substrate, and facilitating the improvement of the conductive performance of the conductive trace after curing.

[0032] In the present application, part of the organic binder in the conductive paste is transferred by the micro-porous structure on the substrate, and the organic binder in the conductive paste can be spontaneously infiltrated into the micro-porous structure of the substrate by capillary force (wetting force) and gravity, which can be achieved by standing for a period of time or equivalent methods. The specific time can be set by experience, for example, 1-60 minutes.

[0033] The substrate in the embodiments of the present application is not limited to rigid substrate, flexible substrate or stretchable substrate from the perspective of flexibility; it is not limited to polymer substrate or non-polymer substrate from the perspective of material; and it is not limited to single substrate or composite substrate. Specifically, the substrate in the embodiments of the present application is not limited to PET, PI, PTFE, PC, ABS, LCP, PU, TPU, FR4, paper, wood, glass, stone or fabric. Preferably, the substrate in the embodiments of the present application can be selected from materials that can infiltrate the organic binder in the conductive paste, or in other words, the organic binder in the conductive paste can be selected from materials that can infiltrate the substrate.

[0034] In the embodiments of the present application, the substrate with micro-porous structure can be directly used as the substrate with corresponding structure on the market, or the micro-porous structure can be formed on the substrate by mechanical or laser etching. Preferably, the micro-porous structure in the embodiments of the present application is a uniform structure.

[0035] In addition, the carrier portion in the embodiments of the present application can be part or the whole of the substrate, and the conductive paste applied on the carrier portion is not limited to completely covering the carrier portion, covering part of the carrier portion or covering both the carrier portion and the non-carrier portion, as long as the conductive paste is applied on the carrier portion with micro-porous structure.

[0036] The conductive paste in the embodiments of the present application at least includes organic binder and conductive particles; in addition, in some embodiments, the conductive paste can also include solvent, auxiliary agent, etc.; generally, the conductive paste includes organic binder, conductive particles, solvent and auxiliary agent.

[0037] The conductive particles in the conductive paste mainly serve as conductive particles, and the organic binder, the solvent and the auxiliary agent are mainly used to adjust the conductive paste to be uniformly decomposed and to meet the requirements of specific application processes (such as printing (such as spraying), printing (such as screen printing, pad printing, etc.), etc.). In the process of curing the conductive paste, the conductive particles are pulled into each other by the trend of the internal stress of the organic binder with the volatilization of the volatile components of the organic binder, the solvent and the auxiliary agent, and finally the conductive traces composed of the non-volatile components of the organic binder and the conductive particles are formed. The non-volatile components of the organic binder form a film binder for the conductive particles in the conductive traces.

[0038] In the embodiments of the present application, since part of the organic binder in the conductive paste is transferred into the microporous structure of the substrate, the content of the organic binder in the conductive paste on the surface of the substrate is reduced, thereby the thickness of the film binder for the conductive particles can be effectively reduced, the contact resistance in the conductive traces can be effectively reduced, and the conductive performance in the conductive traces can be improved.

[0039] Specifically, the conductive particles are not limited to one or more of gold, silver, copper, zinc, iron, aluminum, nickel, silver-coated copper, gallium, indium, tin, bismuth, conductive carbon black, graphene and carbon nanotubes. In addition, the shape of the conductive particles can be one or more of spherical, needle-like, branch-like and flaky.

[0040] Specifically, the organic binder is not limited to one or more of polyester resin, melamine resin, chlorovinyl acetate resin, chlorovinyl-vinyl acetate copolymer resin, silicone resin, gelatin, sodium alginate, polyvinylpyrrolidone, chitosan, polyurethane resin, polyacrylic acid resin, epoxy resin, fluorocarbon resin, epoxy-acrylic acid resin, epoxy-acrylic ester resin, polyester-acrylic ester resin, phenolic resin, nitrocellulose, ethyl cellulose, alkyd resin, amino resin, chlorovinyl-vinyl acetate copolymer resin, hydroxyl-modified chlorovinyl-vinyl acetate copolymer resin, thermoplastic polyurethane resin, butadiene-styrene rubber resin, butadiene-acrylonitrile rubber resin, isocyanate with blocked groups and oligomers thereof.

[0041] In some embodiments, the solvent and the auxiliary agent can be selected from conventional materials in the art, which are not limited.

[0042] In addition, the conductive paste and the microporous structure in the embodiments of the present application satisfy the following relationship: the particle size of the conductive particles in the conductive paste is greater than the pore size of the microporous structure. Based on the above relationship, the organic binder in the conductive paste can further penetrate into the microporous structure on the substrate, and the conductive particles can be prevented from penetrating into the microporous structure, thereby ensuring that the content of the conductive particles on the surface of the substrate is basically maintained unchanged.

[0043] Specifically, the pore size of the microporous structure on the substrate in the embodiment of the present application can be 1 nm-2 mm, and the conductive particles in the conductive paste can satisfy the above relationship.

[0044] Preferably, under the premise of satisfying the above relationship, the average pore size of the microporous structure can be 1-50 μm, and the average particle size of the conductive particles can be 2-200 μm. In the preferred scheme, the substrate of the microporous structure and the conductive paste have lower cost and are easy to implement.

[0045] Since the conductive particles in the conductive paste are completely infiltrated and coated by the organic binder during preparation, the conductive particles are not easy to directly block the microporous structure, but occasionally, the microporous structure may be blocked, and the local organic binder (film former) content is relatively high. In this regard:

[0046] Preferably, as shown in Figure 3 Figure 3 is a structural example of the microporous structure of the substrate in the embodiment of the present application. The microporous structure 101 in the embodiment of the present application can be provided with a notch 102 close to the port of the conductive paste, that is, the microporous structure 101 is provided with a notch 102 at the port contacting the conductive paste. The notch 102 is used to avoid the port of the microporous structure being directly blocked by the conductive particles, so that the organic binder cannot smoothly infiltrate the microporous structure.

[0047] Preferably, the conductive particles in the embodiment of the present application can also be selected in a sheet shape, a branch shape, and a needle shape. Since the conductive particles in these shapes have low fitting degree with the shape of the microporous port, they are not easy to block the microporous structure. In addition, the inventors have found that as long as the conductive particles contain one or more of the sheet shape, the branch shape, and the needle shape, and the content exceeds 50% of the total conductive particles, the phenomenon of blockage can be avoided with high probability.

[0048] On the other hand, in the embodiment of the present application, the proportion of the organic binder in the conductive paste on the surface of the substrate is reduced, and the proportion of the conductive particles in the conductive paste on the surface of the substrate is increased. After solidification, the thickness of the film former binding the conductive particles can be reduced, thereby facilitating the increase of the exposed area of the conductive particles, improving the solderability, electroplatability, and chemical platability of the conductive particles, and improving the matching degree with the subsequent process (soldering, electroplating, and chemical plating).

[0049] Preferably, in order to further improve the matching degree of the conductive trace and the subsequent process, the conductive particles in the conductive paste can be selected as metal particles, which are beneficial to improve the infiltration degree and bonding force between the solder and the plating layer.

[0050] ​Preferably, the organic binder in the conductive paste can be selected from epoxy resin, and the softening point of the epoxy resin is higher than 100℃, the epoxy equivalent is higher than 5000g / eq, and the molecular weight is higher than 10000g / mol. When the softening point of the epoxy resin is higher than 100℃ and / or the molecular weight of the epoxy resin is higher than 10000, the epoxy resin has better heat resistance, so that the conductive circuit made of the epoxy resin can withstand a higher temperature welding process, and is more widely and conveniently applied.

[0051] Optionally, as shown in Figure 4 , Figure 4 is a second flow example of the method for manufacturing the conductive structure in the embodiment of the present application. After the conductive trace is obtained, the method can further include:

[0052] Step S14, depositing at least one metal reinforcing layer on the conductive trace.

[0053] The metal reinforcing layer is not limited to a solder layer or a plating layer. The plating layer is not limited to one or a stack of several of gold, nickel, copper, silver, zinc, and aluminum.

[0054] Since the thickness of the film-forming substance binding the conductive particles is reduced after the conductive paste on the surface of the substrate is cured, the scratch resistance of the conductive trace is also reduced to a certain extent, and the conductive particles are prone to peeling under external force. However, forming the metal reinforcing layer on the surface of the conductive trace can not only improve the structural stability and scratch resistance of the conductive trace, but also be beneficial to further reducing the contact resistance of the conductive trace, thereby improving the conductive performance of the conductive trace.

[0055] In some embodiments, as shown in Figure 5 , Figure 5 is a structure example of the conductive structure in the embodiment of the present application. During the curing process of the conductive paste, the organic binder in the microporous structure 101 is also cured to form a reinforcing portion 40 in an integral structure with the conductive trace 30 on the surface of the carrier portion.

[0056] In this embodiment, the reinforcing portion 40 in an integral structure with the conductive trace 30 on the surface of the substrate is formed in the microporous structure 101, so that the transverse and longitudinal multi-directional connecting force between the conductive trace 30 and the substrate 10 is improved, thereby greatly improving the adhesion of the conductive trace 30 on the surface of the substrate 10.

[0057] Preferably, as shown in Figure 6 , Figure 6 is a third flow example of the method for manufacturing the conductive structure in the embodiment of the present application. The present application also discloses a method for manufacturing a conductive structure, which includes:

[0058] Step S21, providing a substrate;

[0059] wherein the substrate has a bearing part with a plurality of micro-pore structures;

[0060] Step S22, applying a conductive paste in direct contact with the micro-pore structures on the surface of the bearing part of the substrate, and allowing part of the organic adhesive in the conductive paste to infiltrate into the micro-pore structures, to obtain the conductive paste with reduced proportion of organic adhesive on the surface of the bearing part;

[0061] wherein the conductive paste and the micro-pore structures satisfy the following relationship: the particle size of the conductive particles in the conductive paste is greater than the pore size of the micro-pore structures;

[0062] Step S23, performing curing treatment on the conductive paste on the surface of the bearing part and the organic adhesive infiltrated into the micro-pore structures, to obtain a conductive trace on the surface of the bearing part and a reinforcing part in an integrated structure with the conductive trace in the micro-pore structures.

[0063] Step S24, depositing at least one metal reinforcing layer on the conductive trace.

[0064] wherein the conductive particles in the conductive paste in the embodiment are metal particles, and the organic adhesive is epoxy resin.

[0065] The present application transfers part of the organic adhesive in the conductive paste by the micro-pore structures on the substrate, thereby reducing the proportion of the organic adhesive in the conductive paste on the surface of the substrate, increasing the proportion of the conductive particles in the conductive paste on the surface of the substrate, and facilitating the improvement of the conductive performance of the conductive trace after curing. On the other hand, due to the reduction of the proportion of the organic adhesive in the conductive paste on the surface of the substrate and the increase of the proportion of the conductive particles in the conductive paste on the surface of the substrate in the embodiment of the present application, the thickness of the film-forming substance binding the conductive particles can be reduced after curing, thereby facilitating the increase of the exposed area of the conductive particles, the improvement of the performance of soldering, electroplating and chemical plating, and the matching degree with the subsequent process (soldering, electroplating and chemical plating). In the embodiment, the reinforcing part in an integrated structure with the conductive trace on the surface of the substrate is formed in the micro-pore structures, which can improve the connection force between the conductive trace and the substrate in the horizontal and vertical directions, thereby greatly improving the adhesion of the conductive trace on the surface of the substrate.

[0066] Another object of the present application is to provide a conductive structure to solve the technical problems in the prior art.

[0067] The embodiment of the present application discloses a conductive structure, which comprises a substrate and a conductive trace on the surface of the substrate. Figure 5As shown, the conductive structure comprises: a substrate 10 having a carrier portion with a plurality of micro-pore structures 101; and a conductive trace 30 formed on the carrier portion; wherein the conductive trace 30 is formed by curing a conductive paste, and before curing is completed, part of the organic binder in the conductive paste penetrates into the micro-pore structures, and the organic binder not penetrating into the micro-pore structures forms a film 31 binding the conductive particles 22; wherein the conductive paste and the micro-pore structures satisfy the following relationship: the particle size of the conductive particles 22 in the conductive paste is greater than the pore size of the micro-pore structures 101.

[0068] Optionally, the conductive structure further comprises: at least one metal reinforcing layer formed on the surface of the conductive trace.

[0069] Optionally, the conductive structure further comprises: a reinforcing portion 40 located in the micro-pore structures 101 and integrated with the conductive trace 30 on the surface of the carrier portion.

[0070] The parameters and materials of the conductive structure in the embodiments of the present application can refer to the related embodiments of the manufacturing method of the conductive structure described above, and will not be repeated here. In addition, the conductive structure in the embodiments of the present application can also be directly manufactured by using the related embodiments of the manufacturing method of the conductive structure described above.

[0071] Those skilled in the art will further understand that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein can be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the particular application and design constraints imposed on the overall system. Skilled artisans can implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.

Claims

1. A method for fabricating an electrically conductive structure, the method comprising: The application relates to a method for manufacturing a conductive trace on a substrate. The method comprises the following steps: providing a substrate; the substrate has a bearing part with a plurality of micro-pore structures; applying a conductive paste on the surface of the bearing part of the substrate and directly contacting the micro-pore structures, and allowing part of the organic adhesive in the conductive paste to infiltrate the micro-pore structures, so as to obtain the conductive paste with reduced proportion of organic adhesive on the surface of the bearing part; wherein the conductive paste and the micro-pore structures satisfy the following relationship: the particle size of the conductive particles in the conductive paste is greater than the pore size of the micro-pore structures; 2. The method for manufacturing a conductive structure according to claim 1, wherein: carrying out a curing treatment on the conductive paste, so as to obtain the conductive trace on the surface of the bearing part. Before the step of applying the conductive paste, the method further comprises the following step:

3. The method of claim 1, wherein forming the micro-pore structures on the substrate by means of mechanical and / or laser etching. After the step of obtaining the conductive trace, the method further comprises the following step:

4. The method of claim 1, wherein depositing at least one metal reinforcing layer on the conductive trace.

5. The method of claim 1, wherein The conductive particles in the conductive paste comprise one or more of the following shapes: sheet, branch and needle.

6. The method of claim 1, wherein The micro-pore structures are provided with notches close to the ports of the conductive paste. During the step of carrying out the curing treatment on the conductive paste, the method further comprises the following step:

7. The method of claim 1, wherein the organic adhesive in the micro-pore structures is cured together, so as to form a reinforcing part in an integral structure with the conductive trace on the surface of the bearing part.

8. An electrically conductive structure, characterized by The substrate is made of a material capable of infiltrating the organic adhesive. The application also relates to a substrate with a conductive trace. The substrate has a bearing part with a plurality of micro-pore structures; the conductive trace is formed on the bearing part by curing a conductive paste, and part of the organic adhesive in the conductive paste infiltrates the micro-pore structures before the curing is completed; 9. The electrically conductive structure of claim 8, wherein, wherein the conductive paste and the micro-pore structures satisfy the following relationship: the particle size of the conductive particles in the conductive paste is greater than the pore size of the micro-pore structures. The method further comprises the following step:

10. The electrically conductive structure of claim 8, wherein, forming at least one metal reinforcing layer on the surface of the conductive trace. The method further comprises the following step: forming a reinforcing part in an integral structure with the conductive trace on the surface of the bearing part in the micro-pore structures.

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