Preparation method of metal-based circuit board

Abstract

The invention discloses a preparation method of a metal-based circuit board. In some embodiments, the preparation method comprises the following steps that an initial metal boss is manufactured on the surface of at least one side of a metal substrate, and the outline of the initial metal boss is larger than the outline of a target metal boss when observed in the thickness direction of the metal substrate; a circuit substrate is manufactured on the surface of at least one side of the metal substrate, and the initial metal boss is arranged to penetrate through the circuit substrate; according to a set area of a target metal boss in the circuit substrate, laser ablation is carried out on the part, exceeding the range of the set area, of the initial metal boss, so that the target metal boss consistent with the set area in position is obtained; filling an insulating material in the laser ablated area; and carrying out whole board copper plating and surface circuit manufacturing on the circuit surface of the metal-based circuit board. According to the invention, the relative position precision between the metal boss and the circuit on the upper surface of the circuit substrate can be ensured.

Description

Technical Field

[0001] The present invention relates to the field of circuit boards; more specifically, it relates to a method for preparing a metal-based circuit board. Background Art

[0002] A metal-based circuit board typically includes a metal substrate and a circuit substrate provided with conductive lines. The circuit substrate is disposed on the metal substrate having excellent thermal conductivity, which can well solve the thermal aging problem of semiconductor heating elements and ensure the stability of semiconductor heating elements during use. Further, metal bosses can be provided on the metal substrate, and the metal bosses can be used as heat conduction channels penetrating the circuit substrate and / or as conductive grounding components together with the metal substrate.

[0003] In the prior art, a typical preparation method for such a metal-based circuit board structure is to first fabricate metal bosses on the metal substrate, then laminate the circuit substrate on which the inner-layer lines have been fabricated on the metal substrate, and after lamination, perform surface line fabrication and interlayer interconnection between the surface lines and the inner-layer lines. However, during the lamination process, the circuit substrate usually shifts relative to the metal bosses to a certain extent, resulting in the following problems:

[0004] For example, when Mark points are set on the metal bosses as positioning references to fabricate the surface lines, although the relative positions of the surface lines and the metal bosses are ensured, since the inner-layer lines and the surface lines are fabricated before and after lamination respectively, the interlayer connection positions of the two are likely to be misaligned, reducing the connection reliability between the conductive vias and the interlayer connection positions, and even directly opening the circuit in severe cases. If Mark points are set on the core board of the circuit substrate as positioning references to fabricate the surface lines and the inner-layer lines, although the two can be accurately interconnected layer by layer, the relative positions of the surface lines and the metal bosses cannot be guaranteed, and defects such as the metal bosses being etched, the distance between the surface lines and the metal bosses being too close, and the surface lines being wrongly connected to the metal bosses are likely to occur during the fabrication of the surface lines. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the main object of the present invention is to provide a method for preparing a metal-based circuit board to improve the relative position accuracy between the metal bosses and the circuit substrate.

[0006] To achieve the above main object, the first aspect of the present invention discloses a method for preparing a metal-based circuit board, including the following steps:

[0007] S110, fabricating initial metal bosses on at least one surface of the metal substrate; wherein, when observing along the thickness direction of the metal substrate, the contour of the initial metal bosses forms a contour larger than that of the target metal bosses;

[0008] S120, fabricate a circuit board on at least one side surface of the metal substrate, and set the initial metal boss to penetrate through the circuit board;

[0009] S130, with reference to the set area of the target metal boss in the circuit board, laser ablate the part of the initial metal boss that exceeds the range of the set area, so as to obtain a target metal boss that is consistent with the position of the set area;

[0010] S140, fill an insulating material in the area ablated by laser;

[0011] S150, perform full-board copper plating and surface circuit fabrication on the circuit surface of the metal-based circuit board.

[0012] Further, the metal substrate is a copper substrate, and in step S110, the initial metal boss is obtained by locally etching the corresponding surface of the copper substrate.

[0013] Further, the initial metal boss is set to increase the unilateral dimension by 0.3 mm to 0.8 mm compared with the target metal boss.

[0014] Further, in step S120, the circuit board is obtained by laminating a prepreg and a copper-clad core board on at least one side surface of the metal substrate.

[0015] Further, in step S140, a resin plug hole method is used to fill the area ablated by laser with a resin used as the insulating material.

[0016] To achieve the above main purpose, a second aspect of the present invention discloses a preparation method of a metal-based circuit board, including the following steps:

[0017] S210, fabricate an initial metal boss on at least one side surface of the metal substrate; wherein, when observing along the thickness direction of the metal substrate, the contour of the initial metal boss is formed to be smaller than the contour of the target metal boss;

[0018] S220, fabricate a circuit board on at least one side surface of the metal substrate, and set the initial metal boss to penetrate through the circuit board;

[0019] S230, with reference to the set area of the target metal boss in the circuit board, laser ablate the part within the range of the set area that is not occupied by the initial metal boss;

[0020] S240, fill copper in the area ablated by laser, so as to obtain a target metal boss that is consistent with the position of the set area;

[0021] S250, perform full-board copper plating and surface circuit fabrication on the circuit surface of the metal-based circuit board.

[0022] Further, the metal substrate is a copper substrate, and in step S210, the initial metal boss is obtained by locally etching a corresponding surface of the copper substrate.

[0023] Further, the initial metal boss is set to have a unilateral dimension reduced by 0.3 mm to 0.8 mm compared to the target metal boss.

[0024] Further, in step S220, the circuit substrate is obtained by laminating a prepreg and a copper-clad core board on at least one surface of the metal substrate, and a through hole having the same size as the set area of the target metal boss is machined in the copper-clad core board.

[0025] Further, the copper filling in step S240 and the full-board copper plating in step S250 can be carried out separately or simultaneously.

[0026] The technical solution of the present invention has the following beneficial effects:

[0027] In the preparation method of the present invention, an initial metal boss larger or smaller than the target metal boss is first fabricated on the metal substrate. After the circuit substrate fabrication steps, the initial metal boss is then "corrected" according to the set area of the target metal boss in the circuit substrate to obtain a target metal boss that is in the same position as the set area. Therefore, the position of the target metal boss in the circuit substrate can be accurately controlled, thereby ensuring reliable electrical connection between the surface circuit and the inner-layer circuit and the relative position between the surface circuit and the target metal boss.

[0028] In order to more clearly illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic structural diagram of the metal-based circuit board in Embodiment 1;

[0030] Figure 2 is a flowchart of the preparation method of the metal-based circuit board in Embodiment 1;

[0031] Figure 3 is a schematic structural diagram of the double-sided copper-clad core board used to fabricate the circuit substrate in Embodiment 1;

[0032] Figure 4 is a schematic diagram of the positional relationship between the initial metal boss and the circuit substrate after laminating to fabricate the circuit substrate in Embodiment 1;

[0033] Figure 5 is a schematic structural diagram after obtaining the target metal boss by laser ablation in Embodiment 1;

[0034] Figure 6It is a schematic structural diagram after filling an insulating material in the laser ablation area in Embodiment 1;

[0035] Figure 7 It is a schematic structural diagram of manufacturing a surface circuit on the circuit surface of the metal-based circuit board in Embodiment 1;

[0036] Figure 8 It is a flow chart of the manufacturing method of the metal-based circuit board in Embodiment 2;

[0037] Figure 9 It is a schematic structural diagram of the double-sided copper-clad core board used for manufacturing the circuit board in Embodiment 2;

[0038] Figure 10 It is a schematic diagram of the positional relationship between the initial metal bump and the circuit board after laminating to manufacture the circuit board in Embodiment 2;

[0039] Figure 11 It is a schematic structural diagram after laser ablation of the circuit board in Embodiment 2 to form a copper-filling area;

[0040] Figure 12 It is a schematic structural diagram after filling copper in the laser ablation area in Embodiment 2;

[0041] Figure 13 It is a schematic structural diagram of manufacturing a surface circuit on the circuit surface of the metal-based circuit board in Embodiment 2;

[0042] Figure 14 It is a schematic structural diagram of the metal-based circuit board in Embodiment 2. Detailed implementation manners

[0043] Many specific details are set forth in the following description in order to fully understand the present invention, but the present invention can also be implemented in other forms of changes or substitutions based on this. Therefore, other implementable manners that can be known to those skilled in the art based on the embodiments described in this application all fall within the protection scope of the present invention.

[0044] Embodiment 1

[0045] As Figure 1 shown, the metal-based circuit board involved in the embodiment includes a metal substrate 10 and a circuit board 20 provided on one side of the metal substrate 10. The metal substrate 10 has a metal bump 11 (also described as a target metal bump 11 hereinafter) provided in the circuit board 20. The metal bump 11 can be in the shape of a circle, a rectangle, etc., and the present invention does not limit this.

[0046] Specifically, the metal substrate 10 can be a copper substrate, and the metal boss 11 can be a copper boss having an integrally formed structure with the copper substrate. The circuit substrate 20 is adhesively connected to the metal substrate 10 through the prepreg 22 which is a part of it. Inner layer circuits 201 and surface circuits 202 are fabricated on the circuit substrate 20, and are electrically connected through conductive vias ( Figure 1 not shown in the figure) serving as interlayer interconnecting vias. Device pads 231 are provided on the metal boss 11.

[0047] Combined Figures 2 - 7 As shown, the preparation method of the metal-based circuit board in Embodiment 1 includes the following steps:

[0048] S110, fabricate an initial metal boss 11a on one side surface of the metal substrate 10; wherein, when observing along the thickness direction of the metal substrate 10, the contour of the initial metal boss 11a is formed to be larger than the contour of the target metal boss 11.

[0049] S120, fabricate the circuit substrate 20 on one side surface of the metal substrate 10, and the initial metal boss 11a is set to penetrate through the circuit substrate 20.

[0050] S130, referring to the set area of the target metal boss 11 in the circuit substrate 20, laser ablate the part of the initial metal boss 11a that extends beyond the set area range to obtain the target metal boss 11 that is consistent with the set area.

[0051] S140, fill the insulating material 222 in the area 20a ablated by laser.

[0052] S150, perform full-panel copper plating and fabricate the surface circuits 202 on the circuit surface of the metal-based circuit board.

[0053] Specifically, in step S110, the initial metal boss 11a can be obtained by locally etching the corresponding surface of the metal substrate 10 such as a copper substrate. As a variation of the embodiment, the initial metal boss 11a can also be obtained by local electroplating on the metal substrate 10, or the fabricated initial metal boss 11a can be fixedly connected to the metal substrate 10 by methods such as welding and bonding.

[0054] In step S120, the circuit substrate 20 is obtained by laminating the prepreg 22 and the copper-clad core board 21 on one side surface of the metal substrate 10. Exemplarily, such as Figure 1As shown in the figure, the copper-clad core board 21 includes an inner copper foil 211, an outer copper foil 212, and an insulating core board 210 disposed therebetween; before the lamination step, the copper-clad core board 21 is drilled, copper-plated, and inner-layer circuit is fabricated to process inner-layer circuit 201 and conductive vias 203 on the inner copper foil 211. The conductive vias 203 are used to electrically connect the interlayer connection positions 201a of the inner-layer circuit 201 and the interlayer connection positions 202a of the outer-layer circuit 202; in addition, before the lamination step, a through hole 21a for the initial metal boss 11a to pass through is also processed in the copper-clad core board 21 (as Figure 3 shown), and the unilateral dimension of the through hole 21a is preferably 0.3 mm to 0.8 mm larger than that of the initial metal boss 11a.

[0055] As Figure 4 shown, after lamination, a part of the prepreg 22 will form a resin filling portion 221 that fills the gap between the through hole 21a and the side wall of the initial metal boss 11a. It should be noted that during the lamination of the circuit board 20, the position of the initial metal boss 11a will also shift relative to the circuit board 20, and the shift situation often occurs randomly and is not necessarily the shift situation as Figure 4 shown. It is easy to understand that although the initial metal boss 11a will also shift relative to the circuit board 20 after lamination, since the contour dimension of the initial metal boss 11a is designed to be larger than that of the target metal boss 11, even if there is a shift, the initial metal boss 11a can still be laser-ablated to obtain the target metal boss 11.

[0056] Specifically, in order to ensure obtaining the target metal boss 11, the contour dimension of the initial metal boss 11a can be designed as follows: the set area of the target metal boss 11 after the circuit board 20 is fabricated is still within the contour range of the initial metal boss 11a, and on this basis, the contour dimension of the initial metal boss 11a is minimized as much as possible. Preferably, the initial metal boss 11a is set to be 0.3 mm to 0.8 mm larger than the unilateral dimension of the target metal boss 11 to reduce the required ablation amount. Exemplarily, when the contour dimension of the target metal boss 11 is 7 mm X 4 mm, the contour dimension of the initial metal boss 11a can be 8 mm X 5 mm (the unilateral dimension is increased by 0.5 mm).

[0057] As Figure 5 shown, after the target metal boss 11 is obtained by laser ablation, the ablated part forms a recessed area 20a. In step S140, a resin plugging method can be used to fill the recessed area 20a ablated by laser with a resin used as the insulating material 222 (as Figure 6 ). For the specific implementation method of resin plugging holes, reference can be made to the prior art, and the present invention will not describe it in detail herein.

[0058] In step S150, first, the entire surface of the metal-based circuit board is electroplated with copper to obtain the surface copper foil layer 23, and then the surface copper foil layer 23 and the outer copper foil 212 are etched to obtain the surface circuit 202 and the device pad 231 (as shown in Figure 1 and Figure 7 ). Preferably, before the entire surface is electroplated with copper, the circuit surface is ground to form a flat board surface to improve the flatness of the surface copper foil layer 23.

[0059] In the present invention, the target metal bump 11, the surface circuit 202, and the inner layer circuit 201 can use the same Mark point as the position reference, for example, uniformly referring to the Mark point used by the inner layer circuit 201. In this way, as shown in Figure 3 and Figure 7 , the interlayer connection positions 201a of the inner layer circuit 201 and the interlayer connection positions 202a of the outer layer circuit 202 are aligned with each other, and the two can achieve stable electrical connection through the conductive vias 203; at the same time, since the actual position of the target metal bump 11 in the circuit board 20 is consistent with its set area (the theoretical position determined with reference to the Mark point), the relative position between the metal bump 11 and the surface circuit 202 can also be precisely controlled.

[0060] Embodiment 2

[0061] As shown in Figures 8 - 14 , the method for preparing the metal-based circuit board in Embodiment 2 includes the following steps:

[0062] S210, fabricate an initial metal bump 11b on one surface of the metal substrate 10, for example, locally etch the corresponding surface of the metal substrate 10 to obtain the initial metal bump 11b; wherein, when observed along the thickness direction of the metal substrate 10, the contour of the initial metal bump 11b is formed to be smaller than the contour of the target metal bump 11.

[0063] S220, fabricate the circuit board 20 on one surface of the metal substrate 10, and the initial metal bump 11b is arranged to penetrate through the circuit board 20.

[0064] S230, with reference to the set area of the target metal bump 11 in the circuit board 20, laser ablation is performed on the part within the set area range that is not occupied by the initial metal bump 11b;

[0065] S240, fill copper in the area 20b ablated by laser to obtain the target metal bump 11 that is consistent with the set area (see Figure 11 and Figure 12 ).

[0066] S250, perform entire-surface copper plating and fabricate the surface circuit 202 on the circuit surface of the metal-based circuit board.

[0067] Optionally, in Embodiment 2, the initial metal boss 11b can be set to have a unilateral dimension reduced by 0.3 mm to 0.8 mm compared to the target metal boss 11, so as to reduce the amount of copper filling required for fabricating the target metal boss 11. Exemplarily, when the contour dimension of the target metal boss 11 is 7 mm X 4 mm, the contour dimension of the initial metal boss can be 6 mm X 3 mm (with a unilateral dimension reduced by 0.5 mm).

[0068] In Embodiment 2, as Figure 9 shown, a through hole 21b for the initial metal boss 11b to pass through is machined in the copper-clad core board 21. The size of the through hole 21b is preferably set to exactly match the set area of the target metal boss 11, thereby reducing the difficulty of laser ablation (as Figure 10 and Figure 11 shown, only the resin filling part 221 within the through hole 21b needs to be ablated).

[0069] As Figure 11 and Figure 12 shown, after copper filling in the recessed area 20b ablated by laser, the target metal boss 11 consistent with the set area can be obtained. In some implementation cases, the copper filling in step S240 and the whole-board copper plating in step S250 can be carried out simultaneously. In some implementation cases, copper can be filled (including but not limited to electroplating copper filling) in the area 20b ablated by laser to obtain the target metal boss 11 consistent with the set area, and then the whole-board copper plating and the surface circuit 202 fabrication are carried out. Preferably, before the whole-board copper plating, the circuit surface is ground to form a flat board surface to improve the flatness of the surface copper foil layer 23.

[0070] Other descriptions of Embodiment 2 can refer to Embodiment 1 and will not be repeated here.

[0071] It is easy to understand that although the above embodiments illustrate the present invention by taking the setting of metal bosses and circuit boards on one side surface of the metal substrate as an example, in other embodiments of the present invention, metal bosses and circuit boards can be simultaneously set on two opposite surfaces of the metal substrate. Additionally, the circuit board can adopt a laminated structure of multiple copper-clad core boards or a mixed pressing structure of copper foil and copper-clad core board.

[0072] Although the present invention is disclosed as above with specific embodiments, these specific embodiments are not intended to limit the scope of implementation of the present invention. Any person of ordinary skill in the art, without departing from the scope of the present invention, can make some changes / replacements, that is, any equivalent changes made in accordance with the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a metal-based circuit board, comprising the following steps: S110, fabricate an initial metal boss on at least one surface of the metal substrate; wherein, When observing along the thickness direction of the metal substrate, the contour of the initial metal boss is formed to be larger than that of the target metal boss; S120, fabricating a circuit substrate on at least one surface of the metal substrate, and the initial metal boss is arranged to penetrate through the circuit substrate; S130, referring to the set area of the target metal boss in the circuit substrate, laser-ablate the part of the initial metal boss that extends beyond the set area range to obtain a target metal boss that is in the same position as the set area; S140, filling an insulating material in the area ablated by laser; S150, performing full-panel copper plating and surface circuit fabrication on the circuit surface of the metal-based circuit board.

2. The preparation method of the metal-based circuit board according to claim 1; wherein, The metal substrate is a copper substrate, and step S110 obtains the initial metal boss by locally etching the corresponding surface of the copper substrate.

3. The preparation method of the metal-based circuit board according to claim 1; wherein, The initial metal boss is set to have a unilateral dimension that is 0.3 mm to 0.8 mm larger than that of the target metal boss.

4. The method for preparing a metal-based circuit board according to claim 1; wherein, Step S120 obtains the circuit substrate by laminating a prepreg and a copper-clad core board on at least one surface of the metal substrate.

5. The manufacturing method of the metal-based circuit board according to claim 1; wherein, Step S140 fills the resin used as the insulating material in the area ablated by laser by using the resin plug hole method.

6. A method for preparing a metal-based circuit board, comprising the following steps: S210, fabricate an initial metal boss on at least one side surface of the metal substrate; wherein, When observing along the thickness direction of the metal substrate, the contour of the initial metal boss is formed to be smaller than that of the target metal boss; S220, fabricating a circuit substrate on at least one surface of the metal substrate, and the initial metal boss is arranged to penetrate through the circuit substrate; S230, referring to the set area of the target metal boss in the circuit substrate, laser-ablate the part within the set area range that is not occupied by the initial metal boss; S240, fill copper in the area ablated by laser to obtain a target metal boss that is in the same position as the set area; S250, performing full-panel copper plating and surface circuit fabrication on the circuit surface of the metal-based circuit board.

7. The method for preparing a metal-based circuit board according to claim 6; wherein, The metal substrate is a copper substrate, and step S210 obtains the initial metal boss by locally etching the corresponding surface of the copper substrate.

8. The method for preparing the metal-based circuit board according to claim 6; wherein, The initial metal boss is set to have a unilateral dimension that is 0.3 mm to 0.8 mm smaller than that of the target metal boss.

9. The method for preparing a metal-based circuit board according to claim 6; wherein, Step S220 obtains the circuit substrate by laminating a prepreg and a copper-clad core board on at least one surface of the metal substrate, and through holes with the same size as the set area of the target metal boss are processed in the copper-clad core board.

10. The method for preparing a metal-based circuit board according to claim 6; wherein, The copper filling in step S240 and the full-panel copper plating in step S250 are carried out separately or simultaneously.

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