A double-sided circuit board

Abstract

The utility model discloses a double -sided circuit board relates to electronic additive manufacturing technical field. This double -sided circuit board, include: insulating base material, the through -hole of passing through insulating base material and form in the inside of through -hole, to realize the conductive column of conductive interconnection of insulating base material two sides, wherein, the conductive column includes: the first conductive column and the second conductive column of succession, wherein, the first conductive column is formed through first conductive slurry, and the second conductive column is formed through second conductive slurry, wherein, the height of first conductive column and second conductive column are less than the thickness of insulating base material, and the height of second conductive column is no more than 30um. The application solves the problem of poor quality of slurry plug hole.

Description

Technical Field

[0001] This utility model belongs to the field of electronic additive manufacturing technology, and in particular relates to a double-sided circuit board and its manufacturing method. Background Technology

[0002] Double-sided circuit boards achieve interconnection between circuits on both sides through metallized vias (also known as vias). Through-hole plugging is one of the mainstream processes for achieving metallized vias. Its principle is to plug conductive paste into the through-hole. With the help of a negative pressure adsorption worktable, the conductive paste is adhered to the wall of the through-hole. After curing, a conductive structure connecting the two sides can be formed on the wall of the through-hole.

[0003] However, the aforementioned conductive structure attached to the wall is actually very thin. When plugging the holes, defects such as discontinuity and cross-section are prone to occur, leading to a decrease or even loss of conductivity. Furthermore, the conductivity of all conductive pastes currently on the market is generally poor, at least two orders of magnitude lower than that of pure copper. This results in a very high resistance value for the metallized holes, limiting their application to electronic products with low conductivity requirements and severely restricting the product range of the plugging process.

[0004] Currently, in order to improve the conductivity of slurry plugging, one approach is to directly fill the through-hole with conductive slurry, forming conductive pillars on both sides of the through-hole. However, several problems arise during the manufacturing process: a negative pressure adsorption platform cannot be used, as the slurry in the through-hole cannot form a filling structure under negative pressure during plugging. If the negative pressure adsorption platform is removed, it will have a significant impact on the flatness and fixation of the substrate. Moreover, without negative pressure, it is difficult for the plugging slurry to reach the bottom of the through-hole. Utility Model Content

[0005] In view of this, one objective of this utility model is to propose a double-sided circuit board and its manufacturing method to solve the problems of difficulty in implementing and poor quality of forming conductive pillars by filling holes with paste in the prior art.

[0006] In some illustrative embodiments, the method for manufacturing the double-sided circuit board includes: providing an insulating substrate; forming a first through-hole penetrating the insulating substrate on the insulating substrate; providing an ink blocker on a second surface of the insulating substrate, thereby modifying the first through-hole into a first blind hole with its opening located on a first surface of the insulating substrate; inserting a first conductive paste into the first blind hole from the second surface of the insulating substrate, utilizing the plugging resistance generated by the compressed air cavity formed at the bottom of the blind hole during plugging, thereby forming a first conductive post at the upper part of the first blind hole to close the first blind hole; wherein the height of the first conductive post is lower than the thickness of the insulating substrate; removing the ink blocker, thereby forming a second blind hole with its opening located on the second surface of the insulating substrate; wherein the depth of the second blind hole is not greater than 30 μm; inserting a second conductive paste into the second blind hole from the second surface of the insulating substrate, thereby forming a second conductive post connected to the first conductive post.

[0007] In some alternative embodiments, while inserting the first conductive paste into the first blind hole from the first surface of the insulating substrate, a patterned first conductive line is formed on the first surface of the insulating substrate using the first conductive paste; and / or, while inserting the second conductive paste into the second blind hole from the second surface of the insulating substrate, a patterned second conductive line is formed on the second surface of the insulating substrate using the second conductive paste.

[0008] In some alternative embodiments, the end of the first conductive post away from the first surface of the insulating substrate has an arc-shaped concave structure.

[0009] In some alternative embodiments, the first conductive paste and the second conductive paste may be the same or different conductive pastes.

[0010] In some alternative embodiments, the height of the first conductive post is 10–40 μm; and / or the diameter of the first through hole is 10–300 μm.

[0011] In some optional embodiments, before the ink blocker is disposed on the second surface of the insulating substrate, the method further includes: forming a capacity-enhancing layer on the second surface of the insulating substrate, the capacity-enhancing layer having a second through-hole communicating with a first through-hole on the insulating substrate; the ink blocker is disposed on the side of the capacity-enhancing layer away from the insulating substrate, and the second through-hole on that side is closed, thereby transforming the first through-hole and the second through-hole into a first blind hole; wherein the second through-hole is used to increase the volume of the compressed air chamber; the step of removing the ink blocker and forming a second blind hole with its opening located on the second surface of the insulating substrate includes: removing the ink blocker and the capacity-enhancing layer, and forming a second blind hole with its opening located on the second surface of the insulating substrate.

[0012] Another objective of this invention is to provide a double-sided circuit board to solve the problems existing in the prior art.

[0013] In some illustrative embodiments, the double-sided circuit board includes: an insulating substrate, a through-hole penetrating the insulating substrate, and conductive pillars formed inside the through-hole for achieving conductive interconnection on both sides of the insulating substrate; wherein, the conductive pillars include: a first conductive pillar and a second conductive pillar connected together; wherein, the first conductive pillar is formed by a first conductive paste, and the second conductive pillar is formed by a second conductive paste; wherein, the height of both the first and second conductive pillars is less than the thickness of the insulating substrate, and the height of the second conductive pillar is not greater than 30 μm.

[0014] In some alternative embodiments, the double-sided circuit board further includes: a first conductive line formed on the first surface of the insulating substrate using the first conductive paste; and / or, a second conductive line formed on the second surface of the insulating substrate using the second conductive paste.

[0015] In some alternative embodiments, the height of the first conductive post is 10–40 μm.

[0016] In some alternative embodiments, the diameter of the first through hole is 10–300 μm.

[0017] In some alternative embodiments, the height of the second conductive post is no greater than 20 μm.

[0018] In some alternative embodiments, the height of the first conductive post is 20–40 μm; and / or the diameter of the first through hole is 100–150 μm.

[0019] In some alternative embodiments, the ends of the first conductive post that contact the second conductive post have an arc-shaped concave structure.

[0020] Compared with the prior art, this application has the following advantages:

[0021] This application first uses an ink resist sheet to transform the through-hole on the insulating substrate into a first blind hole. Then, the first blind hole is plugged with slurry. The air compressed and accumulated at the bottom of the first blind hole during plugging generates plugging resistance against the slurry, thereby forming a first conductive post on the upper part of the first blind hole to seal it. After removing the ink resist sheet, a second blind hole with the first conductive post as its bottom surface can be formed. Since the depth of the second blind hole is no more than 30μm, during the process of plugging the hole again with slurry to form the second conductive post, as much air as possible can be discharged from the second blind hole, thus achieving the plugging of the second conductive post and its contact connection with the first conductive post. Attached Figure Description

[0022] Figure 1 This is a process example of the manufacturing method of the double-sided circuit board in this utility model embodiment;

[0023] Figure 2 This is a second example of the manufacturing process of the double-sided circuit board in this utility model embodiment;

[0024] Figure 3 This is a structural example of the method for manufacturing a double-sided circuit board in this utility model embodiment;

[0025] Figure 4 This is a height example of the structure of the method for manufacturing a double-sided circuit board in this utility model embodiment. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0027] It should be noted that, where there is no conflict, the various technical features in the embodiments of this utility model can be combined with each other.

[0028] This utility model discloses a method for manufacturing a double-sided circuit board, specifically, as follows: Figure 1-4 As shown, Figure 1 This is a process example of the manufacturing method of the double-sided circuit board in this utility model embodiment; Figure 2 This is a second example of the manufacturing process of the double-sided circuit board in this utility model embodiment; Figure 3 This is a structural example of the method for manufacturing a double-sided circuit board in this utility model embodiment; Figure 4 This is a height example of a structural example of a method for manufacturing a double-sided circuit board according to an embodiment of this utility model; the manufacturing method includes:

[0029] Step S11: Provide an insulating substrate 10;

[0030] Step S12: Form a first through hole 21 through the insulating substrate 10 in the insulating substrate 10;

[0031] Step S13: An ink blocking sheet 30 is provided on the second surface of the insulating substrate 10, and the first through hole 21 is modified into a first blind hole 22 with the opening located on the first surface of the insulating substrate 10.

[0032] Step S14: Insert the first conductive paste into the first blind hole 22 from the second surface of the insulating substrate 10. Utilize the blocking resistance generated by the compressed air cavity 40 formed at the bottom of the blind hole during the blocking process to form a first conductive post 41 at the upper part of the first blind hole 22, sealing the first blind hole 21. The height of the first conductive post 41 is less than the thickness of the insulating substrate (i.e., the first conductive post 41 does not completely fill the first blind hole 22 (first through hole 21)).

[0033] Step S15: Remove the ink block 30 and form a second blind hole 23 on the insulating substrate 10 with the orifice located on the second surface of the insulating substrate 10; wherein the depth of the second blind hole 23 is not greater than 30μm;

[0034] Step S16: Insert the second conductive paste into the second blind hole 23 from the second surface of the insulating substrate 10 to form a second conductive post 61 connected to the first conductive post 51.

[0035] This application first uses an ink resist sheet to transform the through-hole on the insulating substrate into a first blind hole. Then, the first blind hole is plugged with slurry. The air compressed and accumulated at the bottom of the first blind hole during plugging generates plugging resistance against the slurry, thereby forming a first conductive post on the upper part of the first blind hole to seal it. After removing the ink resist sheet, a second blind hole with the first conductive post as its bottom surface can be formed. Since the depth of the second blind hole is no more than 30μm, during the process of plugging the second blind hole again with slurry to form the second conductive post, as much air in the second blind hole can be discharged as much as possible, thereby achieving good plugging formation of the second conductive post and contact connection with the first conductive post.

[0036] The insulating substrate in this embodiment of the present invention can be a rigid board or a flexible board. Rigid boards include, but are not limited to: FR-4, CEM-1, 22F, CEM-3, wood, glass, plastic, PMMA (acrylic), etc.; flexible boards include, but are not limited to: PET, PVC, PU, ​​PC, PP, PA, PI, CPI (transparent PI), TPE, TPU, TPV, etc.; preferably, the insulating substrate in this embodiment of the present invention can be PI or PET.

[0037] The first and / or second conductive pastes in this embodiment of the invention may be low-temperature conductive pastes, mainly comprising resin and conductive fillers; wherein, the conductive fillers are not limited to one or more of gold, silver, copper, iron, nickel, zinc, aluminum, palladium, conductive carbon black, and graphene. The hole-filling process employed includes, but is not limited to, screen printing, and other methods of filling holes with conductive paste, such as using a squeegee to force the conductive paste into the holes.

[0038] In this embodiment of the invention, the first conductive paste and the second conductive paste need to be cured (the solvent partially evaporates) to form the corresponding first conductive pillar and the second conductive pillar.

[0039] In this embodiment of the invention, the first conductive paste and the second conductive paste can be the same or different conductive pastes. For example, the first conductive paste is silver paste and the second conductive paste is carbon paste; both the first and second conductive pastes are silver paste; the first conductive paste is carbon paste and the second conductive paste is silver paste; or both the first and second conductive pastes are carbon paste.

[0040] In this embodiment of the present invention, the first conductive post 51 and the second conductive post 61 are formed within the first through hole 20. Therefore, the heights of the first conductive post 51 and the second conductive post 61 are both less than the height of the first through hole 20 (i.e., the thickness of the insulating substrate). The sum of the heights of the first conductive post 51 and the second conductive post 61 should be equal to or close to the height of the first through hole 20 (i.e., the thickness of the insulating substrate 10).

[0041] In this embodiment of the invention, the depth of the second blind hole 23 is designed to be no greater than 30 μm. The applicant has found that when plugging blind holes within this depth range, the inserted slurry can squeeze out as much air as possible from the second blind hole, allowing the conductive slurry to reach the bottom of the blind hole and form a better contact surface with the pre-formed first conductive post. Furthermore, the second conductive post does not need to form a closed structure at the orifice like the first conductive post, thus allowing for the creation or design of gaps to expel air on the second conductive post, reducing the shape requirements of the second conductive post. In some embodiments of the invention, the depth of the second blind hole is the same as the height of the second conductive post.

[0042] In this embodiment of the invention, the second conductive paste, by venting the air in the second blind hole as much as possible, will also make full contact with the first conductive post as much as possible. Therefore, the first conductive post will also act like the hole wall to bond and bind the paste. During the curing process of the second conductive paste, the second conductive paste will avoid shrinkage and deformation on one side of the first conductive post, thus reducing the contact area between the two and reducing the contact resistance between them.

[0043] For example, the depth of the second blind hole 23 in this embodiment of the present invention can be 30μm, 26μm, 20μm, 15μm, 10μm, 8μm, 3μm, etc.

[0044] Preferably, the depth of the second blind hole 23 in this embodiment of the present invention is designed to be no more than 20 μm. With this hole depth, it is beneficial to further expel and exhaust the air in the second blind hole 23 during the plugging process, while reducing the risk of air leakage gaps on the second conductive post 61. It is also beneficial for the second conductive paste to fill the second blind hole 23 completely, improving conductivity while ensuring appearance quality.

[0045] In some embodiments of the present invention, the end (end face) of the first conductive post 51 away from the first surface of the insulating substrate 10 (i.e. the end where the first conductive post contacts the second conductive post) is an arc-shaped concave structure; wherein, the concave structure is a structure that is recessed in the direction of the center of the first conductive post 51.

[0046] The formation of the arc-shaped concave structure is due to two factors: First, when the first conductive slurry plugs the hole, it is subject to the plugging resistance of the air at the bottom. Since the bonding strength between the slurry and the hole wall is greater than that of the central area of ​​the plugging slurry, the plugging resistance causes extrusion deformation to the center of the plugging slurry area. Second, during the curing process after plugging, the slurry will further shrink and deform due to the disappearance of volatile substances in the slurry.

[0047] In this embodiment, the arc-shaped concave structure of the first conductive post 51 eliminates the dead corner area at the bottom of the second blind hole 23, which in turn facilitates the further discharge of air from the second blind hole 23 during the process of plugging the hole with the second conductive paste.

[0048] In some embodiments of the present invention, the end of the second conductive post 61 that contacts the first conductive post 51 has an arc-shaped outward convex structure.

[0049] Continue to participate in the exhibition Figure 4 In some embodiments, the height of the first conductive post 51 in this embodiment of the present invention specifically refers to the distance H1 between the center of the first surface of the insulating substrate 10 and the center of the end face of the first conductive post 51 away from the first surface of the insulating substrate 10; the height of the second conductive post 61 specifically refers to the distance H2 between the center of the second surface of the insulating substrate 10 and the center of the end face of the second conductive post 61 away from the second surface of the insulating substrate 10. In some embodiments, the sum of the heights H1 of the first conductive post and H2 of the second conductive post is the thickness L of the insulating substrate 10.

[0050] In some embodiments of the present invention, the height of the first conductive post 51 may be not less than 10 μm. This is because if the height of the first conductive post 51 is less than 10 μm, the structural strength of the bottom of the second blind hole 23 formed by the first conductive post 51 as the hole bottom will be low, making it prone to damage when the second conductive paste is used to plug the hole, thus affecting product quality. For example, the height of the first conductive post 51 may be 10 μm, 15 μm, 21 μm, 30 μm, 40 μm, 60 μm, 80 μm, etc.

[0051] Preferably, the height of the first conductive post 51 in this embodiment of the present invention is not greater than 40 μm. If the height of the first conductive post 51 is too large, the process parameters for plugging the hole will be difficult to adjust, affecting the product quality.

[0052] Furthermore, in this embodiment of the present invention, the height of the first conductive post 51 can be 20 to 40 μm. The first conductive post 51 under this parameter is easy to implement and has a stable and reliable structure.

[0053] In some embodiments, the aperture of the first through hole 21 in this utility model can range from 10 to 300 μm; preferably, the aperture of the first through hole 21 in this utility model can range from 100 to 150 μm.

[0054] The ink blocking sheet 30 in this embodiment of the present invention can be made of flexible board or rigid board. Rigid board includes, but is not limited to: FR-4, CEM-1, 22F, CEM-3, wood, glass, plastic, PMMA (acrylic), etc.; flexible board includes, but is not limited to PET, PVC, PU, ​​PC, PP, PA, PI, CPI (transparent PI), TPE, TPU, TPV, etc.

[0055] Preferably, when the insulating substrate 10 is a flexible board, the ink blocking sheet 30 in this embodiment of the present invention can be a flat and rigid sheet or plate, which is beneficial to prevent the deformation of the insulating substrate during the hole plugging process and can be used for stable fixation of the negative pressure adsorption platform.

[0056] In some embodiments, before the ink blocker 30 is disposed on the second surface of the insulating substrate 10, the present invention may further include: forming a capacity-enhancing layer 70 on the second surface of the insulating substrate 10, the capacity-enhancing layer 70 having a second through hole 24 communicating with the first through hole 21 on the insulating substrate 10; wherein, the ink blocker 30 is disposed on the side of the capacity-enhancing layer 70 away from the insulating substrate 10, and the second through hole 24 on that side is closed, and the first through hole 21 and the second through hole 24 are transformed into a first blind hole 22; wherein, the second through hole 24 is used to increase the volume of the compressed air chamber; in this embodiment, by disposing of the capacity-enhancing layer 70 between the insulating substrate 10 and the ink blocker 30, the volume of the compressed air chamber 40 is increased by utilizing the second through hole 23, thus reducing the plugging resistance to a certain extent, and increasing the plugging depth of the first conductive paste (i.e., increasing the height of the first conductive post 51) under the same plugging parameters, thereby meeting the need for deeper plugging.

[0057] Based on the above-described embodiments of the capacity-enhancing layer, the removal of the ink blocker in this embodiment of the present invention, forming a second blind hole with the orifice located on the second surface of the insulating substrate, may include: removing the ink blocker and the capacity-enhancing layer, and forming a second blind hole with the orifice located on the second surface of the insulating substrate.

[0058] The capacity-enhancing layer 70 in this embodiment of the present invention can be made of flexible board or rigid board. Rigid board includes, but is not limited to: FR-4, CEM-1, 22F, CEM-3, wood, glass, plastic, PMMA (acrylic), etc.; flexible board includes, but is not limited to PET, PVC, PU, ​​PC, PP, PA, PI, CPI (transparent PI), TPE, TPU, TPV, etc.

[0059] The function of the second through hole 24 in the capacity-enhancing layer 70 in this embodiment of the present invention is to increase the volume of the compressed air chamber 40. Therefore, it is sufficient to ensure that the second through hole 24 is connected to the first through hole 21. At the same time, this application does not limit the height of the second through hole 24 (the thickness of the capacity-enhancing layer), and it can be set according to actual needs.

[0060] Preferably, in this embodiment of the present invention, the capacity-enhancing layer 70 can be stacked on the insulating substrate 10 before the first through hole 21 penetrating the insulating substrate 10 is formed, so that the first through hole 21 and the second through hole 24 with the same shape are formed simultaneously by drilling once.

[0061] In some embodiments, while inserting the first conductive paste into the first blind hole 22 from the first surface of the insulating substrate 10, a patterned first conductive line 52 is formed on the first surface of the insulating substrate 10 using the first conductive paste; and / or, while inserting the second conductive paste into the second blind hole 23 from the second surface of the insulating substrate 10, a patterned second conductive line 62 is formed on the second surface of the insulating substrate 10 using the second conductive paste.

[0062] In this embodiment, the integrated printing process can achieve the formation of the first conductive line and the first conductive post in one printing, and the formation of the second conductive line and the second conductive post in two printings. Compared with the traditional process of printing after printing (or printing after printing), the number of steps is reduced by half, effectively improving the process efficiency.

[0063] It should be understood that the first conductive post 51 and the first conductive line 52 in the embodiments of this utility model can be formed in steps, and the second conductive post 61 and the second conductive line 62 can also be formed in steps.

[0064] Another objective of this invention is to provide a double-sided circuit board, which can be manufactured using any of the methods described above.

[0065] This utility model embodiment also discloses a double-sided circuit board, specifically, as follows: Figure 1-4As shown, the double-sided circuit board includes: an insulating substrate 10, a through hole penetrating the insulating substrate 10, and conductive pillars formed inside the through hole for achieving conductive interconnection on both sides of the insulating substrate 10; wherein, the conductive pillars include: a first conductive pillar 51 and a second conductive pillar 52 connected together; wherein, the first conductive pillar 51 is formed by a first conductive paste, and the second conductive pillar 52 is formed by a second conductive paste; wherein, the height of both the first conductive pillar 51 and the second conductive pillar 52 is less than the thickness of the insulating substrate 10, and the height of the second conductive pillar 52 is not greater than 30μm.

[0066] In some embodiments of the present invention, the double-sided circuit board may further include: a first conductive line 52 formed on a first surface of an insulating substrate 10 using a first conductive paste; and / or a second conductive line 62 formed on a second surface of an insulating substrate 10 using a second conductive paste.

[0067] In some embodiments, the height of the first conductive post 51 in this invention can be 10–40 μm. Further, the height of the first conductive post 51 in this invention can be 20–40 μm.

[0068] In some embodiments of the present invention, the diameter of the first through hole 21 is 10–300 μm. Further, in some embodiments of the present invention, the diameter of the first through hole 21 is 100–150 μm.

[0069] In some embodiments of the present invention, the height of the second conductive post 61 may not exceed 20 μm.

[0070] In some embodiments of the present invention, the ends of the first conductive post 51 that contact the second conductive post 61 are arc-shaped concave structures.

[0071] In some embodiments of the present invention, the end of the second conductive post 61 that contacts the first conductive post 51 has an arc-shaped outward convex structure.

[0072] The selection of materials, processes, and parameters of the double-sided circuit board in this embodiment of the present invention can be referred to the embodiments of the above-described method for manufacturing double-sided circuit boards, and will not be repeated here.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A double-sided wiring board, characterized by, include: An insulating substrate, a through-hole penetrating the insulating substrate, and a conductive post formed inside the through-hole to achieve conductive interconnection on both sides of the insulating substrate; The conductive pillar includes a first conductive pillar and a second conductive pillar connected together; wherein the first conductive pillar is formed by a first conductive paste, and the second conductive pillar is formed by a second conductive paste. The heights of both the first and second conductive pillars are less than the thickness of the insulating substrate, and the height of the second conductive pillar is no greater than 30 μm.

2. The double-sided circuit board according to claim 1, characterized by It also includes: forming a first conductive line on the first surface of the insulating substrate using the first conductive paste; and / or forming a second conductive line on the second surface of the insulating substrate using the second conductive paste.

3. The double-sided circuit board according to claim 1, characterized by The height of the first conductive post is 10–40 μm; and / or the diameter of the through hole is 10–300 μm; and / or the first conductive paste and the second conductive paste are the same or different conductive pastes.

4. The double-sided circuit board according to claim 3, characterized by The height of the first conductive post is 20–40 μm; and / or the diameter of the through hole is 100–150 μm; and / or the height of the second conductive post is not greater than 20 μm.

5. The double-sided circuit board according to claim 1, characterized by The end of the first conductive post that contacts the second conductive post has an arc-shaped concave structure.

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