阅读说明：本技术 金属基双面电路板及其制备方法 (Metal-based double-sided circuit board and preparation method thereof ) 是由 袁绪彬 陈爱兵 高卫东 周晓斌 于 2021-09-30 设计创作，主要内容包括：本发明公开了一种金属基双面电路板及其制备方法。实施例的制备方法包括如下步骤：S1、在金属基板上钻第一通孔,并在第一通孔内填充塞孔树脂；S2、在金属基板的两侧压合半固化片和铜箔；S3、在步骤S2得到的电路板上钻第二通孔,第二通孔贯穿塞孔树脂；S4、在第二通孔的内壁和铜箔表面形成覆铜层；S5、对电路板表面的铜箔和覆铜层进行图形化蚀刻,得到导电图案；其中,通过图形化蚀刻,在塞孔树脂区域和/或相邻于塞孔树脂的区域形成应力释放部,应力释放部的铜箔和覆铜层被完全蚀刻。本发明的金属基双面电路板及其制备方法在塞孔树脂区域和/或相邻于塞孔树脂的区域形成应力释放部,可以有效预防爆板缺陷。(The invention discloses a metal-based double-sided circuit board and a preparation method thereof. The preparation method of the embodiment comprises the following steps: s1, drilling a first through hole on the metal substrate, and filling hole plugging resin in the first through hole; s2, pressing a prepreg and a copper foil on two sides of the metal substrate; s3, drilling a second through hole on the circuit board obtained in the step S2, wherein the second through hole penetrates through the hole plugging resin; s4, forming copper-clad layers on the inner wall of the second through hole and the surface of the copper foil; s5, carrying out graphical etching on the copper foil and the copper-clad layer on the surface of the circuit board to obtain a conductive pattern; and forming a stress release part in the region of the plug hole resin and/or the region adjacent to the plug hole resin by patterned etching, wherein the copper foil and the copper-clad layer of the stress release part are completely etched. According to the metal-based double-sided circuit board and the preparation method thereof, the stress release part is formed in the hole plugging resin area and/or the area adjacent to the hole plugging resin, so that the defect of board explosion can be effectively prevented.)

1. A preparation method of a metal-based double-sided circuit board comprises the following steps:

s1, drilling a first through hole on the metal substrate, and filling hole plugging resin in the first through hole;

s2, pressing a prepreg and a copper foil on two sides of the metal substrate;

s3, drilling a second through hole on the circuit board obtained in the step S2, wherein the second through hole penetrates through the hole plugging resin;

s4, forming copper-clad layers on the inner wall of the second through hole and the surface of the copper foil;

s6, carrying out graphical etching on the copper foil and the copper-clad layer on the surface of the circuit board to obtain a conductive pattern;

and forming a stress release part in the region of the plug hole resin and/or the region adjacent to the plug hole resin by the patterned etching, wherein the copper foil and the copper clad layer of the stress release part are completely etched.

2. The method for producing a metal-based double-sided circuit board according to claim 1, wherein the area ratio of the stress relief portion formed in the receptacle resin region to the receptacle resin region is higher than 30%.

3. The method for manufacturing a metal-based double-sided circuit board according to claim 1, wherein the surface of the metal substrate is subjected to a wire drawing process before the prepreg and the copper foil are laminated.

4. The method for manufacturing a metal-based double-sided circuit board according to claim 3, wherein the hole plugging resin is pre-cured and ground to form a flush surface with the metal substrate before the wire drawing process is performed.

5. The method for manufacturing a metal-based double-sided circuit board according to claim 4, wherein the hole plugging resin is post-cured after the wire drawing process and before the prepreg and the copper foil are bonded.

6. The method for manufacturing a metal-based double-sided circuit board according to claim 1, wherein the post-curing temperature of the hole plugging resin is not lower than the laminating temperature for laminating the prepreg and the copper foil.

7. The method for manufacturing a metal-based double-sided circuit board according to claim 1, wherein the first via hole is formed by means of laser processing.

8. A metal-based double-sided circuit board comprising:

the metal substrate is provided with a first through hole, and the first through hole is filled with plug hole resin;

insulating layers provided on both opposite surface sides of the metal substrate;

the patterned metal layer is arranged on the surface of the insulating layer;

and the conductive via hole is electrically connected with the patterned metal layers positioned on the two side surfaces of the metal-based double-sided circuit board and penetrates through the hole plugging resin.

Wherein the patterned metal layer has a stress relief portion in the region of the plug hole resin and/or in a region adjacent to the plug hole resin, the metal of the stress relief portion being completely removed.

9. The metal-based double-sided circuit board according to claim 8, wherein the stress relief portion formed in the receptacle resin region occupies an area ratio of the receptacle resin region higher than 30%.

10. The metal-based double-sided circuit board of claim 8, wherein the metal substrate is an aluminum substrate.

Technical Field

The invention relates to the field of circuit boards; and more particularly, to a metal-based double-sided circuit board and a method for manufacturing the same.

Background

The metal-based circuit board adopts the metal substrate for heat dissipation, has excellent heat-conducting performance, and is more and more widely applied in recent years. When the metal-based double-sided circuit board is manufactured, a metal substrate needs to be drilled, plugging resin is filled in the hole, and then a conductive via hole penetrating through the plugging resin is manufactured so as to realize the electrical connection of circuit layers on two sides of the circuit board.

Chinese patent application CN201110031935.2 discloses a method for manufacturing a metal-based double-sided circuit board, which comprises the following steps: drilling a metal base hole on a metal substrate; transferring the liquid insulating resin into the roughened metal base hole in a screen printing mode, and baking the liquid insulating resin to convert the liquid insulating resin into a solid state; laminating a prepreg and a copper foil on the surfaces of two sides of the metal substrate; and drilling a metal-based resin insulation hole in the center of the circuit board corresponding to each metal-based hole, and then performing hole metallization manufacturing, outer layer circuit manufacturing, resistance welding manufacturing, non-metallization hole drilling manufacturing, surface treatment manufacturing and appearance manufacturing to obtain a circuit board finished product.

The metal-based double-sided circuit board prepared by the method has the defect of easy board explosion due to the large difference of the thermal expansion coefficients of the hole plugging resin, the copper foil and the prepreg (the thermal expansion coefficient of the hole plugging resin is obviously higher than that of the copper foil and the prepreg), and needs to be improved.

Disclosure of Invention

The invention mainly aims to provide a preparation method of a metal-based double-sided circuit board, which can effectively prevent the defect of board explosion.

Another object of the present invention is to provide a metal-based double-sided circuit board which effectively prevents the defect of board explosion.

In order to achieve the above main object, a first aspect of the present invention provides a method for manufacturing a metal-based double-sided circuit board, including the steps of:

s1, drilling a first through hole on the metal substrate, and filling hole plugging resin in the first through hole;

s2, pressing a prepreg and a copper foil on two sides of the metal substrate;

s3, drilling a second through hole on the circuit board obtained in the step S2, wherein the second through hole penetrates through the hole plugging resin;

s4, forming copper-clad layers on the inner wall of the second through hole and the surface of the copper foil;

s6, carrying out graphical etching on the copper foil and the copper-clad layer on the surface of the circuit board to obtain a conductive pattern;

and forming a stress release part in the region of the plug hole resin and/or the region adjacent to the plug hole resin by patterned etching, wherein the copper foil and the copper-clad layer of the stress release part are completely etched.

In the preparation method, the stress release part is formed in the hole plugging resin area and/or the area adjacent to the hole plugging resin, and the copper foil and the copper-clad layer of the stress release part are completely removed, so that a thermal expansion stress release space can be provided for the hole plugging resin when the circuit board works, and the defect of board explosion caused by the difference of thermal expansion coefficients among the hole plugging resin, the copper foil and the prepreg can be effectively prevented.

According to a preferred embodiment of the first aspect of the present invention, the area ratio of the stress relief portion formed in the region of the plug hole resin to the region of the plug hole resin is higher than 30%, and may be in particular 30% to 95%, thereby providing a sufficient thermal expansion stress relief space for the plug hole resin.

According to a preferred embodiment of the first aspect of the present invention, before laminating the prepreg and the copper foil, the surface of the metal substrate is subjected to a wire drawing process to enhance the bonding force between the prepreg and the metal substrate.

Further, the hole plugging resin is pre-cured and ground to form a flush surface with the metal substrate before the wire drawing process. Wherein, before the wire drawing treatment, the hole plugging resin is ground to form a flush surface with the metal substrate, so that the wire drawing effect of the adjacent surface of the metal substrate and the hole plugging resin can be improved.

Further, post-curing the hole plugging resin is performed after the wire drawing process and before the prepreg and the copper foil are laminated.

According to a preferred embodiment of the first aspect of the present invention, the post-curing temperature of the plugging resin is not lower than the pressing temperature of pressing the prepreg and the copper foil. Therefore, the further curing reaction and the internal stress which are possibly generated by the hole plugging resin in the pressing process can be reduced, and the defect of board explosion of the circuit board can be prevented.

According to a preferred embodiment of the first aspect of the present invention, the first through hole is formed by laser processing, so that the first through hole has a rough surface, thereby enhancing the bonding force between the hole plugging resin and the metal substrate.

In order to achieve another object described above, a second aspect of the present invention provides a metal-based double-sided circuit board including:

the metal substrate is provided with a first through hole, and the first through hole is filled with plug hole resin;

insulating layers provided on both opposite surface sides of the metal substrate;

the patterned metal layer is arranged on the surface of the insulating layer;

the conductive via hole is electrically connected with the patterned metal layers positioned on the two side surfaces of the metal-based double-sided circuit board and penetrates through the hole plugging resin;

the patterned metal layer is provided with a stress release part in the region of the hole plugging resin and/or the region adjacent to the hole plugging resin, and the metal of the stress release part is completely removed.

According to a preferred embodiment of the second aspect of the present invention, the area ratio of the stress relief portion formed in the plug hole resin region to the plug hole resin region is higher than 30%, and may be 30% to 95%.

According to a preferred embodiment of the second aspect of the present invention, the metal substrate is an aluminum substrate.

In the metal-based double-sided circuit board, the patterned metal layer is provided with the stress release part in the hole plugging resin area and/or the area adjacent to the hole plugging resin, and the metal of the stress release part is completely removed, so that a thermal expansion stress release space can be provided for the hole plugging resin when the circuit board works, and the defect of board explosion caused by the difference of thermal expansion coefficients between the hole plugging resin, the copper foil and the insulating layer is effectively prevented.

To more clearly illustrate the objects, technical solutions and advantages of the present invention, the present invention will be further described in detail with reference to the accompanying drawings and detailed description.

Drawings

FIG. 1 is a schematic structural diagram of a double-sided metal-based circuit board according to an embodiment of the present invention;

FIG. 2 is a schematic structural view of a stress relieving portion of example 1 of the present invention;

FIG. 3 is a schematic structural view of a stress relieving portion of example 2 of the present invention;

FIG. 4 is a schematic structural diagram of a metal substrate with a first via hole filled with a hole plugging resin according to an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a metal substrate with prepregs and copper foils laminated on both sides thereof according to an embodiment of the method of the present invention;

FIG. 6 is a schematic structural diagram of a circuit board after a second through hole is drilled in the embodiment of the preparation method of the invention;

FIG. 7 is a schematic structural diagram of a circuit board after the whole board is electroplated according to an embodiment of the manufacturing method of the present invention;

FIG. 8 is a schematic structural diagram of a circuit board after completing circuit etching according to an embodiment of the manufacturing method of the invention.

It should be noted that, in order to clearly illustrate the structures that are being represented, the various parts of the drawings may not be drawn to the same scale. Therefore, unless explicitly stated otherwise, the drawings do not limit the dimensions and proportional relationships of the heat dissipation substrate.

Detailed Description

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced with other variations or alternatives that may be based on the present invention. Therefore, other possible implementations that can be known to those skilled in the art based on the embodiments described herein are within the scope of the present invention.

As shown in fig. 1, the metal-based double-sided circuit board according to the embodiment of the present invention includes a metal substrate 1, a cured prepreg 2 as an insulating layer, a patterned metal layer 3, and a conductive via 4. The metal substrate 1 can be a copper substrate or an aluminum substrate, the metal substrate 1 is formed with a first through hole 11, and the first through hole 11 is filled with plug hole resin 12; prepregs 2 are disposed on both opposite surface sides of the metal substrate 1, and patterned metal layers 3 are disposed on the surfaces of the insulating layers 2; the conductive via holes 4 are electrically connected with the patterned metal layers 3 on the two side surfaces of the metal-based double-sided circuit board and penetrate through the hole plugging resin 12.

The patterned metal layer 3 has a stress relief 30 in the region of the plug resin and/or adjacent to the plug resin 12, the metal of the stress relief 30 being completely removed. For example, as shown in fig. 1, the stress relief portion 30 has an overlapping area a with the plug resin 12 in the circuit board thickness direction; that is, at least a portion of the stress relief 30 is located within the receptacle resin region. The metal in the stress release part 30 is removed, so that a thermal expansion stress release space can be provided for the hole plugging resin 12 when the circuit board works, and the defect of board explosion caused by the difference of thermal expansion coefficients between the hole plugging resin 12 and the patterned metal layer 3 and the prepreg 2 is effectively prevented.

In one embodiment of the present invention, as shown in fig. 2, the patterned metal layer 3 has a fan-shaped stress relief portion 30, the stress relief portion 30 is formed in both the region of the plug hole resin (within the dotted circle in the figure) and the region adjacent to the plug hole resin 12 (outside the dotted circle in the figure), and the metal in the stress relief portion 30 is completely removed. In another embodiment of the present invention, as shown in fig. 3, there are a plurality of circular stress relief portions 30 in the region of the receptacle resin (within the dotted circle in the figure).

In the embodiment of the present invention, the area ratio of the stress relief portion 30 formed in the plug hole resin region to the plug hole resin region is preferably higher than 30%, and specifically may be 30% to 95%. Further, the shape of the stress relief portion 30 is not limited, and may be other regular or irregular shapes such as an oval shape, a square shape, and a circular arc shape.

Hereinafter, embodiments of the method for manufacturing the metal-based double-sided circuit board will be described with reference to fig. 4 to 8.

As shown in fig. 4, a first through hole 11 is drilled in the metal substrate 1, and the first through hole 11 is filled with a plugging resin 12. The first through hole 11 may be formed by mechanical or laser processing, preferably by laser processing, to form the first through hole 11 having a roughened surface, thereby enhancing the bonding force of the hole plugging resin 12 with the metal substrate 1.

After the resin is filled in the holes, the hole filling resin 12 can be pre-cured and ground to ensure that the hole filling resin 12 and the metal substrate 1 form a flush surface. Then, the surface of the metal substrate 1 may be subjected to wire drawing processing using a wire drawing machine to form a texture to roughen the surface of the metal substrate 1. After the wire drawing treatment, the metal substrate is cleaned, and then the hole plugging resin 12 is post-cured (baked), wherein the baking temperature of the post-curing (which means the highest temperature in the post-curing stage) is not lower than the laminating temperature for laminating the prepreg and the copper foil (which means the highest temperature in the laminating stage).

As shown in fig. 5, after the post-curing process of the via hole resin 12 is completed, the prepreg 2 and the copper foil 31 are pressed on both sides of the metal substrate 1. Since the surface of the metal substrate 1 is subjected to the wire drawing process, the prepreg can be well bonded to the surface of the metal substrate 1. In another embodiment of the present invention, the surface of the metal substrate 1 may be roughened by another mechanical or chemical method instead of the wire drawing treatment on the surface of the metal substrate 1.

As shown in fig. 6, a second through hole 121 is drilled in the circuit board obtained by the press-fitting, and the second through hole 121 penetrates the hole plugging resin 12. Then, as shown in fig. 7, the circuit board is subjected to full-scale electroless plating and electroplating, a copper-clad layer 32 is formed on the inner wall of the second through hole 121 and the surface of the copper foil 31, and the copper-clad layer 32 on the inner wall of the second through hole 121 forms the conductive via 4.

As shown in fig. 8, the copper foil 31 and the copper-clad layer 32 on the surface of the circuit board are subjected to patterned etching, and the copper foil 31 and the copper-clad layer 32 are formed into a conductive pattern to obtain a patterned metal layer 3; wherein, through the pattern etching, the stress relief part 30 is formed in the region of the plug hole resin and/or the region adjacent to the plug hole resin, and the copper foil 31 and the copper clad layer 32 of the stress relief part 30 are completely etched.

In summary, in the present invention, the conductive pattern (patterned metal layer) forms the stress relief portion in the region of the hole plugging resin and/or the region adjacent to the hole plugging resin, so as to provide a relief space for thermal expansion stress for the hole plugging resin when the circuit board is in operation, thereby effectively preventing the defect of board explosion caused by the difference of thermal expansion coefficients between the hole plugging resin and the copper foil and the prepreg.

Although the present invention has been described with reference to specific embodiments, these embodiments are not intended to limit the scope of the invention. It will be appreciated by those skilled in the art that various changes/substitutions may be made without departing from the scope of the invention, and it is intended that all equivalent changes and modifications made in accordance with the present invention shall be embraced by the scope of the invention.