Circuit board and manufacturing method thereof

Abstract

The invention discloses a circuit board and a manufacturing method thereof, and relates to the technical field of electronic circuit additive manufacturing. The manufacturing method comprises the following steps: step 1, providing an insulating base material; step 2, forming a basic conductive layer on the insulating base material by using low-temperature conductive slurry; 3, at least forming a removable organic protective film on the basic conductive layer; step 4, performing laser ablation on the insulating base material and / or the basic conductive layer; and step 5, removing the organic protective film and splashes generated on the organic protective film in the laser ablation process. Before laser ablation, the basic conductive layer is covered and protected by the organic protective film, so that splash is blocked by the organic protective film and cannot be in direct contact with the basic conductive layer even if the splash is generated in the laser ablation process; and after laser ablation, the organic protective film and splashes on the organic protective film can be directly removed together, so that normal plating of the basic conductive layer is guaranteed.

Description

Technical Field

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

[0002] Laser carbon implantation technology can use the high thermal energy of laser ablation to directly form a carbonized layer on an insulating substrate, and then form a plated conductive layer directly based on the carbonized layer through a plating process. Its attention has been increasing in recent years.

[0003] However, in actual applications, it was found that due to various factors, incomplete vaporization of organic matter is very likely to occur in the laser ablation process. That is, a part of the organic matter ablated by the laser is not completely vaporized and dissipated, but is scattered around the laser treatment point in the form of spatter. After analyzing the spatter, it was found that its resistance is extremely large and it will hardly be plated in the subsequent plating process.

[0004] Therefore, when the aesthetics of the product are compromised, it generally does not have a serious impact on the product quality. However, if the area around the laser processing point is designed to be plated during the plating process, the area will be blocked by spatter and cannot be plated, seriously affecting the production yield of the circuit board product. Summary of the Invention

[0005] In view of this, an object of the present invention is to propose a method for manufacturing a circuit board to solve the problem in the prior art that the spatter generated by laser ablation blocks the target plating area and prevents plating, resulting in a decrease in the production yield of the circuit board product.

[0006] In some illustrative embodiments, the method for manufacturing a circuit board includes:

[0007] Step 1: providing an insulating substrate;

[0008] Step 2: forming a basic conductive layer on the insulating substrate using a low-temperature conductive paste;

[0009] Step 3: forming a removable organic protective film at least on the base conductive layer;

[0010] Step 4: performing laser ablation on the insulating substrate and / or the base conductive layer;

[0011] Step 5: Remove the organic protective film and the splashes generated thereon during the laser ablation process.

[0012] In some optional embodiments, performing laser ablation on the insulating substrate and / or the basic conductive layer includes: converting a portion of the basic conductive layer and / or a portion of the insulating substrate into a carbonized layer by laser ablation.

[0013] In some optional embodiments, the method for manufacturing the circuit board further includes: step 6, forming a plated conductive layer on the base conductive layer and / or the carbonized layer through a plating process.

[0014] In some optional embodiments, the carbonized layer includes: a first carbonized layer on the via hole wall formed by laser ablation.

[0015] In some optional embodiments, the via hole penetrates the basic conductive layer and the insulating substrate, and the first carbonized layer is formed by converting the basic conductive layer and the insulating substrate together under laser ablation.

[0016] In some optional embodiments, the basic conductive layer includes a first basic conductive layer and a second basic conductive layer formed on opposite sides of the insulating substrate; the via hole sequentially penetrates the first basic conductive layer, the insulating substrate and the second basic conductive layer, and the first carbonized layer is formed by the first basic conductive layer, the insulating substrate and the second basic conductive layer being transformed together under the action of laser ablation.

[0017] In some optional embodiments, the carbonized layer includes: forming a non-penetrating second carbonized layer on the surface of the printed conductive layer or the insulating substrate by laser ablation.

[0018] In some optional embodiments, the conductive filler in the low-temperature conductive paste includes metal particles; and the surface of the carbonized layer is a mixed interface including a carbonized interface and a metal interface.

[0019] In some optional embodiments, the organic protective film further covers the insulating substrate.

[0020] Another object of the present invention is to provide a circuit board to solve the problems in the prior art.

[0021] In some illustrative embodiments, the circuit board is obtained by any one of the manufacturing methods described above.

[0022] Compared with the existing technology, this application has the following advantages:

[0023] The present invention uses an organic protective film to cover and protect the base conductive layer before laser ablation. Therefore, even if splashes are generated during the laser ablation process, they will be blocked by the organic protective film and cannot directly contact the base conductive layer. After laser ablation, the organic protective film and the splashes thereon can be directly removed, thereby ensuring the normal plating of the base conductive layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic flow chart of a method for manufacturing a circuit board in an embodiment of the present invention;

[0025] Figure 2 is a process diagram of a method for manufacturing a circuit board in an embodiment of the present invention;

[0026] Figure 3 This is a high-magnification electron microscope image of the carbon-planted interface of the via hole in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0028] It should be noted that the various technical features in the embodiments of the present invention can be combined with each other without conflict.

[0029] The embodiment of the present invention discloses a method for manufacturing a circuit board, specifically, as follows: Figure 1-2 As shown, Figure 1 1 is a flow chart of a method for manufacturing a circuit board in an embodiment of the present invention. Figure 2 : is a process diagram of a method for manufacturing a circuit board in an embodiment of the present invention; the method for manufacturing a circuit board includes:

[0030] Step S10, providing an insulating substrate 10;

[0031] Step S20: forming a base conductive layer 20 on the insulating substrate 10 using a low-temperature conductive paste;

[0032] Step S30, forming a removable organic protective film 30 at least on the base conductive layer 20;

[0033] Step S40, performing laser ablation on the insulating substrate 10 and / or the base conductive layer 20;

[0034] Step S50 , removing the organic protection film 30 and the splashes 50 generated thereon during the laser ablation process.

[0035] The present invention uses an organic protective film to cover and protect the base conductive layer before laser ablation. Therefore, even if splashes are generated during the laser ablation process, they will be blocked by the organic protective film and cannot directly contact the base conductive layer. After laser ablation, the organic protective film and the splashes thereon can be directly removed, thereby ensuring the normal plating of the base conductive layer.

[0036] The insulating substrate in the embodiment of the present invention may include: a flexible substrate, a flexible stretchable substrate, a hard substrate, etc., preferably a sheet or film material, etc.; among them, the hard substrate can be selected from traditional PCB boards, such as glass fiber boards, semi-glass fiber boards, specifically FR-4, CEM-1, 22F, CEM-3, etc. In addition to traditional PCB boards, wood, glass, plastic, PMMA (Acrylic), etc. can also be used; and the flexible substrate can include flexible stretchable substrates and flexible non-stretchable substrates, such as PET, PVC, PU, ​​PC, PP, PA, PI, CPI (transparent PI), TPE film, etc. In addition to the above substrates, PDMS, silicone, fabrics (such as non-woven fabrics, nylon, washed cotton, polyester, spandex and woven fabrics blended with various materials, etc.), adhesive films (not limited to TPU, TPV), etc. can also be selected. It should be understood by those skilled in the art that in addition to the above substrates, the substrate in the embodiment of the present invention can also be selected from other substrates in the prior art that can meet the requirements of forming a conductive structure thereon.

[0037] In some embodiments, the insulating substrate in the embodiments of the present invention is particularly suitable for PI or PI-improved substrates to create flexible FPC electronics, and can even meet the needs of PET or PET-improved substrates, which are substrates with lower temperature resistance, thereby increasing the selection range of the substrate and reducing the production cost of printed circuit boards.

[0038] In some embodiments, in step S20, a basic conductive layer is formed on the insulating substrate using a low-temperature conductive paste. This may mean that the basic conductive layer is directly laid on the surface of the insulating substrate, or that the basic conductive layer is formed on the insulating substrate through other intermediates (such as coatings, film layers, etc.).

[0039] Specifically, before applying to form the basic conductive layer, a coating can be first formed on the surface of the insulating substrate, and then the basic conductive layer can be directly formed on the surface of the coating; wherein, when the coating is a conductive coating, the coating can be consistent with the pattern of the basic conductive layer; when the coating is an insulating coating, the coating can cover and exceed the size of the basic conductive layer, and be inconsistent with the pattern of the basic conductive layer.

[0040] The low-temperature conductive paste in the embodiment of the present invention refers to a composite conductive paste mainly composed of a fully mixed conductive filler, a resin binder and a solvent. After the paste is fully cured, the solvent will fully evaporate, thereby converting it into a conductive film bound by a resin film-forming material.

[0041] The conductive filler is not limited to one or more of metal particles, graphene, conductive carbon black, carbon nanotubes, and conductive particles such as core-shell structures. The metal particles are not limited to one or more of gold, silver, copper, iron, nickel, zinc, and silver-coated copper powder. The resin binder can be any commercially available resin, including but not limited to one or more of epoxy resin, acrylic resin, naphthalene-containing epoxy resin, polyaromatic epoxy resin, multifunctional epoxy resin, bismaleimide resin, and polyimide resin. This application does not impose any restrictions on the choice of solvent.

[0042] The curing method of the low-temperature conductive paste in the embodiment of the present invention is not limited to thermosetting, light curing, electromagnetic radiation or other curing methods.

[0043] In some embodiments, laser ablation of the insulating substrate 10 and / or the base conductive layer 20 in step S30 of the embodiments of the present invention may include: converting a portion of the base conductive layer 20 and / or a portion of the insulating substrate 10 into a carbonized layer 40 by laser ablation. Where laser ablation is performed only on the insulating substrate, the region of the insulating substrate irradiated by the laser scanning may be converted into a carbonized layer, and the carbonized layer may be obtained solely through conversion of the insulating substrate. Where laser ablation is performed only on the base conductive layer, the region of the base conductive layer irradiated by the laser scanning may be converted into a carbonized layer, and the carbonized layer may be obtained solely through conversion of the base conductive layer. Where laser ablation is performed simultaneously on the base conductive layer 20 and the insulating substrate 10, the carbonized layer 40 may be composed of a carbonized portion 41 of the base conductive layer and a carbonized portion 42 of the insulating substrate. Therefore, laser ablation may be performed on a portion of the base conductive layer and / or a portion of the insulating substrate as needed to obtain the corresponding carbonized layer.

[0044] In some embodiments, the conductive filler in the low-temperature conductive paste of the present invention may include metal particles, so that a mixed interface including a carbonized interface and a metal interface may be formed on the surface of the carbonized layer formed by laser ablation on the base conductive layer formed by the low-temperature conductive paste, and the plated conductive layer at the corresponding position is attached to the carbonized layer through the mixed interface. Figure 3 , Figure 3 The black spots on the inner wall of the via are carbonized interfaces, and the bright spots on the inner wall are metal interfaces.

[0045] Among them, the carbonized interface refers to the carbon surface directly exposed to the outside, the metal interface refers to the metal surface directly exposed to the outside, and the mixed interface refers to the surface with both carbon and metal exposed to the outside.

[0046] Since the basic conductive layer is a conductive film in which a resin film-forming material binds a conductive filler, wherein the conductive filler is basically evenly distributed in the conductive film, during the laser ablation process, the resin film-forming material and the conductive filler on the laser ablation point or path will be vaporized and removed together, so the carbonized layer contains not only carbon but also conductive filler; in the case where the conductive filler contains metal particles, a mixed interface containing a carbonized interface and a metal interface can be formed during the laser drilling and carbon planting process.

[0047] On the one hand, the carbonized layer with a mixed interface of a carbonized interface and a metal interface not only improves the conductivity, which is beneficial to the plating effect, but also, the plated conductive layer that grows directly on the metal interface during the plating process can generate metal-to-metal wetting force between it and the metal particles, thereby improving the adhesion of the plated conductive layer in the via.

[0048] In some embodiments, the carbonized layer in the embodiments of the present invention may include: a first carbonized layer formed on the via hole wall by laser ablation. When the via hole is located only on the insulating substrate, the first carbonized layer is formed by converting the insulating substrate. When the via hole is located in the overlapping area of ​​the insulating substrate and the base conductive layer, the via hole penetrates the base conductive layer and the insulating substrate. In this case, the first carbonized layer is converted from the base conductive layer and the insulating substrate by laser ablation. In this embodiment, the first carbonized layer can be used to achieve the metallization process during the plating process.

[0049] In which, the basic conductive layer may also include a first basic conductive layer and a second basic conductive layer formed on opposite sides of the insulating substrate; the via hole sequentially penetrates the first basic conductive layer, the insulating substrate and the second basic conductive layer, and the first carbonized layer is formed by the first basic conductive layer, the insulating substrate and the second basic conductive layer being transformed together under the action of laser ablation.

[0050] In some embodiments, the carbonized layer in the embodiment of the present invention may include: forming a non-penetrating second carbonized layer on the surface of the printed conductive layer and / or the insulating substrate by laser ablation. In this embodiment, the second carbonized layer can be used to directly achieve surface plating on the surface of the insulating substrate and / or the basic conductive layer in the plating process; in addition, when the basic conductive layer contains metal particles, the second carbonized layer formed thereon can enhance the adhesion of the plated metal.

[0051] In some embodiments, the carbonized layer in the embodiments of the present invention may include both the first carbonized layer and the second carbonized layer, or one of the two.

[0052] In some embodiments, the method for manufacturing a circuit board in the embodiment of the present invention may further include:

[0053] Step S60 : forming a plated conductive layer 50 on the base conductive layer 20 and / or the carbonized layer 40 through a plating process.

[0054] Specifically, a plated conductive layer can be formed on the carbonized layer by electroplating or chemical plating, wherein the plated conductive layer is formed by sequentially stacking at least one metal. Specifically, the plated conductive layer is not limited to a stack of one or more of copper, nickel, gold, silver, etc.

[0055] Preferably, a plated conductive layer can also be formed on the base conductive layer and the carbonized layer by electroplating or chemical plating process; that is, the carbonized layer is used in conjunction with the base conductive layer, and the plating effect and bonding strength of the plated conductive layer are mainly improved by the carbonized layer.

[0056] Preferably, the metal particles in the low-temperature conductive particles can form an alloy with the plated conductive layer, thereby further improving the adhesion of the plated conductive layer on the carbonized layer.

[0057] Preferably, in the embodiment of the present invention, the plated conductive layer can be formed by an electroplating process, which has advantages such as high efficiency and stable structure compared to a chemical plating process.

[0058] In some embodiments, the organic protective film in the embodiments of the present invention can be composed of easily removable organic materials, including but not limited to copper protectants, flux, etc., which can form a good protective film on the basic conductive layer, thereby isolating the basic conductive layer from splashes, and after the laser ablation is completed, the organic protective film can be removed by an acidic or alkaline solvent; wherein, when selecting the corresponding solvent, it is necessary to consider that the solvent only acts on the organic protective film, so as not to damage the insulating substrate and the basic conductive layer.

[0059] The splash range can be further determined according to the range of the laser ablation area, so that the organic protective film can be formed only on the corresponding area.

[0060] In some embodiments, the organic protective film can be directly applied on the base protective layer using a film material, or can be directly coated on the base protective layer using a coating material.

[0061] In addition to the above-mentioned copper protecting agent and flux, other materials can also be used as long as they can meet the physical isolation effect of spatter.

[0062] In some embodiments, the organic protective film in the embodiments of the present invention may further cover the insulating substrate, thereby preventing splashes from scattering on the insulating substrate and affecting the appearance of the product or other functional requirements.

[0063] Another object of the present invention is to provide a circuit board that can be obtained by any of the above-mentioned manufacturing methods.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for manufacturing a circuit board, characterized in that: include: Step 1: providing an insulating substrate; Step 2: forming a basic conductive layer on the insulating substrate using a low-temperature conductive paste; Step 3, forming a removable organic protective film at least on the base conductive layer; Step 4: performing laser ablation on the insulating substrate and / or the base conductive layer; Step 5: Remove the organic protective film and the splashes generated thereon during the laser ablation process.

2. The method for manufacturing a circuit board according to claim 1, wherein: Laser ablation of the insulating substrate and / or the base conductive layer comprises: Part of the base conductive layer and / or part of the insulating substrate is converted into a carbonized layer by laser ablation.

3. The method for manufacturing a circuit board according to claim 1, wherein: Also includes: Step 6: forming a plated conductive layer on the base conductive layer and / or the carbonized layer through a plating process.

4. The method for manufacturing a circuit board according to claim 2, wherein: The carbonized layer includes: a first carbonized layer formed on the wall of the via hole by laser ablation.

5. The method for manufacturing a circuit board according to claim 4, wherein: The via hole penetrates the basic conductive layer and the insulating substrate, and the first carbonized layer is formed by converting the basic conductive layer and the insulating substrate together under the action of laser ablation.

6. The method for manufacturing a circuit board according to claim 5, wherein: The base conductive layer includes a first base conductive layer and a second base conductive layer formed on opposite sides of the insulating substrate; The via hole sequentially penetrates the first basic conductive layer, the insulating substrate and the second basic conductive layer, and the first carbonized layer is formed by converting the first basic conductive layer, the insulating substrate and the second basic conductive layer under laser ablation.

7. The method for manufacturing a circuit board according to claim 2, wherein: The carbonized layer includes: forming a non-penetrating second carbonized layer on the surface of the printed conductive layer or the insulating substrate by laser ablation.

8. The method for manufacturing a circuit board according to claim 1, wherein: The conductive filler in the low-temperature conductive paste contains metal particles; and the surface of the carbonized layer is a mixed interface including a carbonized interface and a metal interface.

9. The method for manufacturing a circuit board according to claim 1, wherein: The organic protective film also covers the insulating substrate.

10. A circuit board, characterized in that: The method according to any one of claims 1 to 9 is used to obtain the composition.

Images