Circuit board and manufacturing method thereof

Abstract

The application discloses a circuit board and a manufacturing method thereof, and relates to the technical field of electronic circuit manufacturing. The manufacturing method of the circuit board comprises the following steps: providing a prefabricated circuit board; the prefabricated circuit board comprises a first base material, a carbon powder pattern formed on the first base material, and a conductive pattern formed on the region of the first base material which is not covered by the carbon powder pattern; wherein the carbon powder pattern is composed of at least carbon powder and hot melt resin; providing a second base material; the adhesion F1 between the first base material and the carbon powder pattern in a molten state and the adhesion F2 between the second base material and the carbon powder pattern in a molten state satisfy the following relationship: F1 < F2; placing the second base material on the carbon powder pattern of the prefabricated circuit board, and removing the carbon powder pattern from the first base material by a hot-pressing method to obtain a target circuit board. In the application, the removal of the carbon powder pattern is realized by the hot-pressing transfer method, the influence of the carbon powder pattern on the performance of the circuit board is effectively avoided, and the user experience is improved.

Description

Technical Field

[0001] This invention belongs to the field of electronic circuit manufacturing technology, and particularly relates to a circuit board and its manufacturing method. Background Technology

[0002] Liquid metal generally refers to low-melting-point metals that are fluid at room temperature. Due to their combined properties as fluids and good conductors, they have been widely used in the field of additive manufacturing of electronic circuits as a new material to replace traditional copper foil. Currently, liquid metal patterning processes mainly include direct writing, extrusion, printing, and spraying. Among these, liquid metal printing has the highest forming efficiency and the best forming quality. The two-step liquid metal forming process is the most representative. This process first uses a laser printer to form a toner pattern that does not adhere to the liquid metal on a substrate that is to be coated with liquid metal. Then, liquid metal is applied so that it only adheres to the areas of the substrate not covered by the toner pattern, thus achieving liquid metal patterning. This process has the advantages of high forming accuracy, high reliability, fast production efficiency, low cost, easy implementation, no need for screen / roller production, and can meet users' personalized circuit designs.

[0003] While this process can quickly and conveniently create any planar circuit designed by the user using mature laser printing technology, the toner pattern is not a necessary structure in most cases, resulting in a poor user experience. On the other hand, one of the advantages of liquid metal circuits is the flexibility and stretchability of liquid metal. Multiple tests have verified that the maximum stretching of liquid metal flexible stretchable circuits can reach 300%, while the maximum stretching of laser-printed toner patterns, although containing polymer components such as resin, is less than 20%, which seriously limits the stretchability advantage of liquid metal circuits. Summary of the Invention

[0004] In view of this, one object of the present invention is to provide a method for manufacturing a circuit board to solve the problem that toner patterns affect the performance of circuit boards in the prior art.

[0005] In some illustrative embodiments, the method of manufacturing the circuit board includes: providing a pre-fabricated circuit board; the pre-fabricated circuit board includes: a first substrate, a toner pattern formed on the first substrate, and a conductive pattern formed on an area of ​​the first substrate not covered by the toner pattern; wherein the toner pattern is composed of at least toner and hot-melt resin; providing a second substrate; the adhesion force F1 between the first substrate and the toner pattern in the molten state and the adhesion force F2 between the second substrate and the toner pattern in the molten state satisfying: F1 < F2; placing the second substrate on the toner pattern of the pre-fabricated circuit board, and removing the toner pattern from the first substrate by hot pressing to obtain a target circuit board.

[0006] In some alternative embodiments, the conductive pattern is made of a conductive material.

[0007] In some alternative embodiments, the method of manufacturing the prefabricated circuit board includes: providing a first substrate to which the conductive material is adhered; forming a toner pattern on the first substrate to which the conductive material is not adhered; and forming the conductive pattern on an area of ​​the first substrate not covered by the toner pattern, based on the difference in surface selectivity of the first substrate and the toner pattern to the conductive material.

[0008] In some alternative embodiments, the conductive material comprises at least liquid metal.

[0009] In some alternative embodiments, the second substrate does not adhere to the liquid metal.

[0010] In some alternative embodiments, after removing the toner pattern from the first substrate, the method further includes forming an encapsulation layer covering the conductive pattern on the first substrate.

[0011] In some alternative embodiments, the first substrate is a flexible and stretchable substrate.

[0012] In some alternative embodiments, forming the conductive pattern on the area of ​​the first substrate not covered by the toner pattern based on the surface selectivity difference of the first substrate and the toner pattern to the conductive material specifically includes: applying the liquid metal through a coating process so that the liquid metal adheres only to the area of ​​the first substrate not covered by the toner pattern to form the conductive pattern.

[0013] In some alternative embodiments, the toner pattern is formed by a laser toner printer.

[0014] In some alternative embodiments, the toner pattern is removed from the first substrate by hot pressing, specifically including: providing a hot pressing temperature T1, where T2≤T1≤T3; wherein T2 is the softening temperature of the hot melt resin in the toner pattern, and T3 is the minimum value among the heat resistance temperatures of the hot melt resin, the first substrate, and the second substrate.

[0015] Another object of the present invention is to provide a circuit board that can be obtained by the circuit board manufacturing method described in any of the above claims.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] In this invention, toner patterns are removed by hot-press transfer, which effectively avoids the impact of toner patterns on the performance of the circuit board and also improves the user experience. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the manufacturing process of the circuit board in an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of the manufacturing process of the circuit board in an embodiment of the present invention. Detailed Implementation

[0020] The following description and accompanying drawings fully illustrate specific embodiments of the invention to enable those skilled in the art to practice them. Other embodiments may include structural, logical, electrical, procedural, and other changes. The embodiments represent only possible variations. Individual components and functions are optional unless explicitly required, and the order of operation may vary. Some portions and features of some embodiments may be included in or replace portions and features of other embodiments. The scope of embodiments of the invention includes the entire scope of the claims and all available equivalents thereof. In this document, these embodiments of the invention may be referred to individually or collectively with the term "invention," which is merely for convenience and is not intended to automatically limit the scope of the application to any single invention or inventive concept if more than one invention is disclosed.

[0021] It should be noted that, where there is no conflict, the various technical features in the embodiments of the present invention can be combined with each other.

[0022] This invention discloses a method for manufacturing a circuit board, specifically, as follows: Figure 1-2 As shown, Figure 1 This is a flowchart illustrating the manufacturing process of the circuit board in an embodiment of the present invention; Figure 2 This is a schematic diagram of the manufacturing process of the circuit board in an embodiment of the present invention; the method for manufacturing the circuit board includes:

[0023] Step S11: Provide a prefabricated circuit board; wherein the prefabricated circuit board includes: a first substrate 1, a toner pattern 2 formed on the first substrate 1, and a conductive pattern 3 formed on an area of ​​the first substrate 1 not covered by the toner pattern 2; wherein the toner pattern 2 is composed of at least toner and hot melt resin.

[0024] Step S12: Provide a second substrate 4; wherein, the adhesion (also known as bonding force) F1 between the first substrate 1 and the toner pattern 2 in the molten state and the adhesion (also known as bonding force) F2 between the second substrate 4 and the toner pattern 2 in the molten state satisfy: F1 < F2.

[0025] Step S13: Place the second substrate 4 on the toner pattern 2 of the prefabricated circuit board, and remove the toner pattern 2 from the first substrate 1 by hot pressing to obtain the target circuit board.

[0026] In this embodiment of the invention, the toner pattern contains hot-melt resin, so during the hot pressing process, the toner pattern will be in a molten state (i.e., the hot-melt resin is in a molten state). At this time, since the adhesion force F2 between the toner pattern in this state and the second substrate is greater than the adhesion force F1 between the toner pattern in this state and the first substrate, the toner pattern will detach from the first substrate and transfer to the second substrate. After removing the second substrate, the first substrate (i.e., the target circuit board) with only the conductive pattern attached can be obtained.

[0027] In the hot-pressing process, the hot-pressing pressure and temperature are determined based on the properties of the selected first substrate, second substrate, and toner pattern (hot-melt resin). The hot-pressing pressure must be set to ensure close contact between the second substrate and the toner pattern. For the hot-pressing temperature T1, T2 ≤ T1 ≤ T3 must be satisfied. Here, T2 is the softening temperature (initial hot-melt temperature) of the hot-melt resin in the toner pattern, and T3 is the minimum heat resistance temperature among the hot-melt resin, the first substrate, and the second substrate. The heat resistance temperature of the first and second substrates refers to the temperature at which the resin causes deformation of the substrate; for the hot-melt resin, it refers to the temperature at which the hot-melt resin's hot-melt performance fails.

[0028] In this invention, toner patterns are removed by hot-press transfer, which effectively avoids the impact of toner patterns on the performance of the circuit board and also improves the user experience.

[0029] The toner pattern in this embodiment of the invention is not limited to being made of toner material for laser printers; other toner materials containing toner and hot-melt resin can also be used. The thickness of the toner pattern is between 1-5 μm, and toner patterns within this thickness range exhibit good transfer quality and fast transfer efficiency.

[0030] The conductive patterns in this embodiment of the invention are composed of conductive materials. These conductive materials are not limited to liquid metal or liquid metal paste doped with conductive fillers; they can also be conventional conductive metal materials such as gold, silver, copper, aluminum, nickel, and zinc, or conductive structures formed by curing polymer composite conductive ink. Liquid metal, liquid metal paste, and polymer composite conductive ink can be formed by methods such as direct writing, spraying, printing, pad printing, coating, and scraping. Conventional conductive metal materials can be formed by chemical vapor deposition or physical vapor deposition.

[0031] In this embodiment of the invention, liquid metal refers to a low-melting-point elemental metal or alloy with a melting point below 300°C, such as gallium-based alloys, indium-based alloys, bismuth-based alloys, and tin-based alloys. Preferably, the liquid metal in this embodiment is selected from elemental gallium or gallium-based alloys with a melting point below 30°C, such as gallium-indium alloys, gallium-indium-tin alloys, and gallium-indium-tin-zinc alloys. Liquid metals with this melting point can remain in a liquid state at room temperature, making them particularly suitable for use in flexible circuit boards and flexible stretchable circuit boards.

[0032] Among them, the conductive patterns formed by gold, silver, copper, aluminum, nickel, zinc and polymer composite conductive inks have high adhesion and stability on the substrate, so they are not affected by the hot pressing process and remain on the first substrate. For conductive materials containing liquid metal, it is necessary to use a first substrate that adheres to the liquid metal and a second substrate that does not adhere to the liquid metal, and satisfy the above relationship F1 < F2, so as to ensure that the toner pattern is transferred during the hot pressing process, but the liquid metal is not transferred.

[0033] It should be noted that the effect of adhesion or non-adhesion of liquid metal in the embodiments of the present invention can be determined by experiments, or by the following simple method: the substrate or the substrate with the coating is placed at an angle of 20° on the test table, and the liquid metal slurry droplets (volume of 80μL to 120μL, taking 80μL as an example) are dropped from a certain height (2cm to 5cm, taking 2cm as an example) onto the surface of the substrate. If there is no liquid metal residue on the surface of the substrate / coating, it means that the liquid metal does not adhere to the surface of the substrate / coating. If there is liquid metal on the surface of the substrate / coating, it means that the liquid metal adheres to the surface of the substrate / coating.

[0034] The first substrate in the embodiments of the present invention includes, but is not limited to, PU film, TPU film, silicone film, PDMS film, medical PU film, hot melt adhesive film, etc.

[0035] The second substrate in the embodiments of the present invention includes, but is not limited to, wood pulp paper, Xuan paper, cotton towels, copy paper, etc.;

[0036] For example, in embodiments where the conductive pattern is formed using liquid metal or liquid metal paste material, and the toner pattern is formed using toner material from a laser printer, the first substrate is a medical PU film, and the second substrate is copy paper; alternatively, the first substrate is a TPU hot melt adhesive film, and the second substrate is a cotton towel; or, the first substrate is a silicone film, and the second substrate is Xuan paper. Those skilled in the art should understand that, apart from the above selections, the pairing of the first and second substrates only needs to meet the requirements of the above embodiments, and will not be elaborated further here.

[0037] In addition to the above, the first substrate and the second substrate in the embodiments of the present invention may also be selected from other materials that satisfy the above relationship, which will not be elaborated here.

[0038] In some embodiments, the method for manufacturing the prefabricated circuit board includes:

[0039] Step S21: Provide a first substrate to which the conductive material is adhered;

[0040] Step S22: Form the toner pattern on the first substrate without adhering the conductive material;

[0041] Step S23: Based on the difference in surface selectivity of the first substrate and the toner pattern to the conductive material, the conductive pattern is formed on the area of ​​the first substrate not covered by the toner pattern.

[0042] Preferably, in this embodiment, the conductive material used to form the conductive pattern is liquid metal or a liquid metal paste doped with conductive fillers. Specifically, step S23 may include applying liquid metal by coating. During the coating process, since the toner pattern does not adhere to the liquid metal, the liquid metal will not adhere to the toner pattern, but will only adhere to the first substrate not covered by the toner pattern, thereby forming a liquid metal conductive pattern. In addition to the above coating method, the liquid metal can also be applied by methods such as spraying, scraping, or dipping, in conjunction with the toner pattern to achieve a liquid metal patterning process, thereby reducing process requirements. Those skilled in the art should understand that, in addition to the above processes, liquid metal patterning can also be achieved using techniques such as printing, pad printing, and direct writing.

[0043] In some embodiments, after removing the toner pattern from the first substrate, the method further includes forming an encapsulation layer covering the conductive pattern on the first substrate. This encapsulation layer serves to protect the conductive pattern from oxygen, water, scratches, and peeling.

[0044] Preferably, the first substrate in the embodiments of the present invention can be a flexible and stretchable substrate, combined with a conductive pattern formed by liquid metal, which is particularly suitable for fabricating flexible and stretchable circuit boards. Furthermore, when an encapsulation layer is required, the encapsulation layer can also be made of a flexible and stretchable material.

[0045] In some embodiments of the present invention, the toner pattern may be formed by a laser toner printer; wherein, the laser toner printer may be a commercially available laser printer (such as HP-), and may also be a commercially available laser printer cartridge.

[0046] Since the paper feeding mechanism of commercially available laser printers has certain requirements for the strength of the substrate, composite substrates (such as composite substrates of silicone and release film) can be used to meet the paper feeding requirements of laser printers for some substrates that do not meet the paper feeding requirements of laser printers.

[0047] This invention also discloses a circuit board, which can be obtained by the above-described circuit board manufacturing method.

[0048] This invention also provides a method for manufacturing a flexible and stretchable circuit board, comprising:

[0049] Step S31: Provide a composite substrate; the composite substrate is a composite structure of a flexible stretchable substrate and a flexible substrate;

[0050] Step S32: Feed the composite substrate into the laser printer and form a toner pattern on one side of the flexible and stretchable substrate of the composite substrate according to the electronic circuit pattern designed by the user.

[0051] Step S33: Apply liquid metal paste to one side of a flexible stretchable substrate to form a liquid metal conductive pattern that is opposite to the toner pattern.

[0052] Step S34: Provide a transfer substrate;

[0053] Step S35: Place the transfer substrate on the toner pattern and remove the toner pattern from the flexible stretchable substrate by hot pressing.

[0054] Step S36: Form a flexible and stretchable encapsulation layer covering a conductive pattern on a flexible and stretchable substrate.

[0055] Step S37: Remove the flexible substrate from the composite substrate to obtain a flexible stretchable circuit board.

[0056] Those skilled in the art will also understand that the various illustrative logic blocks, modules, circuits, and algorithm steps described in conjunction with the embodiments herein can be implemented as electronic hardware, computer software, or a combination thereof. To clearly illustrate the interchangeability between hardware and software, the various illustrative components, blocks, modules, circuits, and steps described above are generally described in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. Those skilled in the art can implement the described functionality in alternative ways for each specific application; however, such implementation decisions should not be construed as departing from the scope of this disclosure.

Claims

1. A method of manufacturing a circuit board, characterized by, include: Provide a prefabricated circuit board; The prefabricated circuit board includes: a first substrate, a toner pattern formed on the first substrate, and a conductive pattern formed on an area of ​​the first substrate not covered by the toner pattern; wherein the toner pattern is composed of at least toner and hot melt resin. Provide a second substrate; The adhesion force F1 between the first substrate and the toner pattern in the molten state and the adhesion force F2 between the second substrate and the toner pattern in the molten state satisfy the following condition: F1 < F2. The second substrate is placed on the toner pattern of the prefabricated circuit board, and the toner pattern is removed from the first substrate by hot pressing. In this process, since the toner pattern contains hot-melt resin, the toner pattern will be in a molten state during the hot pressing process. At this time, the adhesion force F2 between the toner pattern and the second substrate is greater than the adhesion force F1 between the toner pattern and the first substrate. The toner pattern will detach from the first substrate and transfer to the second substrate. After removing the second substrate, the target circuit board can be obtained.

2. The method of manufacturing a circuit board according to claim 1, wherein The conductive pattern is made of a conductive material; The method for manufacturing the prefabricated circuit board includes: Provide a first substrate for adhering the conductive material; The toner pattern that does not adhere to the conductive material is formed on the first substrate; Based on the difference in surface selectivity of the conductive material between the first substrate and the toner pattern, the conductive pattern is formed on the area of ​​the first substrate not covered by the toner pattern.

3. The method of manufacturing a circuit board according to claim 2, wherein The conductive material contains at least liquid metal.

4. The method of manufacturing a circuit board according to claim 3, wherein The second substrate does not adhere to the liquid metal.

5. The method of manufacturing a circuit board according to claim 4, wherein After removing the toner pattern from the first substrate, the method further includes: An encapsulation layer covering the conductive pattern is formed on the first substrate.

6. The method of manufacturing a circuit board according to claim 4, wherein The first substrate is a flexible and stretchable substrate.

7. The method of manufacturing a circuit board according to claim 4, wherein The step of forming the conductive pattern on an area of ​​the first substrate not covered by the toner pattern, based on the surface selectivity difference of the first substrate and the toner pattern to the conductive material, specifically includes: The liquid metal is applied by a coating process, so that the liquid metal adheres only to the area of ​​the first substrate that is not covered by the toner pattern, thereby forming the conductive pattern.

8. The method of manufacturing a circuit board according to claim 1, wherein The toner pattern is formed using a laser toner printer.

9. The method of manufacturing a circuit board according to claim 1, wherein The toner pattern is removed from the first substrate by hot pressing, specifically including: A hot-pressing temperature T1 is provided, and T2≤T1≤T3; wherein, T2 is the softening temperature of the hot-melt resin in the toner pattern, and T3 is the minimum value among the heat resistance temperatures of the hot-melt resin, the first substrate, and the second substrate.

10. A circuit board, characterized by Obtained by the method of manufacturing a circuit board as described in any one of claims 1-9.

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