Preparation method of circuit board and its metal embedded part

Abstract

This invention discloses a circuit board and a method for manufacturing the same metal embedded component. The method includes the following steps: cutting a metal plate to obtain a metal plate for manufacturing the metal embedded component; leveling the metal plate and then laser-cutting the long side of the metal embedded component; performing a first grinding operation after laser cutting; using a V-cutting tool to cut the short side of the metal embedded component on both sides, retaining a micro-connection portion to the metal plate frame; and performing a second grinding operation after V-cutting. This invention solves both the problem of metal embedded component detachment during grinding and the problem of metal embedded component deformation, thereby improving the quality of the circuit board.

Description

Technical Field

[0001] This invention relates to the field of circuit boards; more specifically, it relates to a method for manufacturing a circuit board and its metal embedded parts. Background Technology

[0002] In the prior art, metal embeds are often placed within resin-based circuit boards (such as FR-4 circuit boards). These metal embeds can be used as heat-conducting and / or conductive components. Typically, the metal embeds are copper blocks, and common processing methods for them include V-cutting, laser cutting, and die-cutting.

[0003] For example, Chinese patent document CN111975220A discloses a processing method for a thermally conductive metal block, including the following steps: providing a metal plate for forming multiple thermally conductive metal blocks; laser-cutting the metal plate according to the shape of the thermally conductive metal block to form a thermally conductive metal block panel; the thermally conductive metal block panel includes a metal support grid, the metal support grid has multiple arrayed grid holes, the thermally conductive metal blocks are disposed in the grid holes, and there are one or more micro-connecting segments connecting the thermally conductive metal blocks and the metal support grid together.

[0004] However, when the metal embedded parts are relatively slender, such as 1X30mm, 2X30mm or 2X60mm, if both the long and short sides are laser-cut, the metal embedded parts are prone to falling off and deforming during the grinding process after laser cutting. If the connection strength of the micro-connection is increased to solve the problem of falling off and deforming, it will make disassembly difficult. If both the long and short sides are V-cut, it is difficult to separate the plates, and the metal embedded parts are prone to deformation during plate separation. If the punching method is used, the punched edges will also warp and deform.

[0005] All of the above-mentioned existing molding methods can lead to warping and deformation of slender metal embedded parts. When these metal embedded parts are embedded in the circuit board through the pressing step, the area where the metal embedded parts are located will have unevenness on the board surface, making it difficult to clean the resin on the surface of the metal embedded parts, and ultimately resulting in open / short circuits or low thermal conductivity. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the main objective of this invention is to provide a method for preparing metal embedded parts for circuit boards, so as to improve the warping and deformation problem in the production process.

[0007] To achieve the above-mentioned main objectives, a first aspect of the present invention discloses a method for preparing a metal embedded part for a circuit board, comprising the following steps:

[0008] Cut the material to obtain a metal plate for making metal embedding parts;

[0009] After the metal plate is leveled, the long side of the metal embedding is laser-cut out.

[0010] The first grinding process is performed after laser cutting;

[0011] The short side of the metal embedding is cut out from both sides using a V-cut blade, and the short side retains the micro-connection part to the metal plate frame;

[0012] A second grinding process is performed after V-cutting.

[0013] In the above technical solution, the long side of the metal embedding is first laser-cut. When the metal slag and burrs generated by laser cutting are removed by grinding, the short side of the metal embedding has not been cut yet. Therefore, the metal embedding will not fall off or deform during grinding. The metal embedding is only connected to the metal plate frame on its V-cut short side. When separating the plates later, the micro-connection of the short side can be broken off with a little force. The metal embedding will not have problems such as deformation or warping. Therefore, it is especially suitable for the production of slender metal embeddings.

[0014] Furthermore, the short side of the metal embedding is V-cut. Because the V-cut process will create a lateral protrusion on the short side, after the metal embedding is pressed onto the circuit board, the lateral protrusion of the short side is embedded in the resin of the circuit board, which will make the embedding of the metal embedding more stable.

[0015] Furthermore, the angle of the V-cut blade is 15 to 30°, and the thickness of the micro-connector is 0.1 ± 0.05 mm.

[0016] In the above technical solution, by specially controlling the angle of the V-cut blade and the size of the micro-connection, it is beneficial to achieve the goal of ensuring that the metal embedded part will not break off due to the grinding plate and is easy to disassemble.

[0017] Furthermore, the first and second grinding processes employ non-woven fabric brushes or nylon pinwheel brushes. Non-woven fabric brushes and nylon pinwheel brushes are relatively soft, thus preventing deformation of the metal inserts during grinding. Using pinwheel brushes also helps remove metal slag and burrs from the cutting grooves.

[0018] Furthermore, the aspect ratio of the metal embedding is greater than 5:1. In particular, even when the aspect ratio of the metal embedding is greater than 10:1 (e.g., 15:1, 30:1), the warping deformation of the metal embedding can still be well suppressed.

[0019] Furthermore, the thickness of the metal plate / metal embedded part is 0.5mm to 3mm.

[0020] Furthermore, the metal plate / metal embedding component is made of copper.

[0021] A second aspect of the present invention discloses a method for manufacturing a circuit board, the circuit board comprising a circuit substrate and a metal embedded member disposed in the circuit substrate; the manufacturing method comprises the following steps:

[0022] Metal embeddings are fabricated according to the aforementioned preparation method;

[0023] The metal embedded part is placed into a stacked structure for fabricating the circuit board and hot-pressed; wherein, buffer pads are respectively provided on the upper and lower sides of the stacked structure during hot pressing.

[0024] Preferably, the buffer pad is made of a high-temperature resistant silicone oil release film with a thickness of 25μm.

[0025] In the above technical solution, the buffer pad uses a high-temperature resistant (≥200℃) silicone oil release film with a thickness of 25μm. This thickness of release film has a suitable buffering effect for the pressing and fixing of slender metal embedded parts. It will not sink in during pressing, and it is easy to peel off when it is bonded to the semi-cured resin.

[0026] According to a specific embodiment of the present invention, the stacked structure includes a copper-clad core board and a prepreg stacked in a predetermined order, wherein the copper-clad core board and the prepreg are provided with through holes corresponding to the positions of the metal embedded parts.

[0027] Furthermore, during hot pressing, aluminum sheets and steel plates are sequentially arranged on the outside of the buffer pad to improve the uniformity of stress and the flatness of the circuit board.

[0028] 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. Attached Figure Description

[0029] Figure 1 This is a flowchart illustrating the processing of the metal embedded parts in the embodiment;

[0030] Figure 2 This is a schematic diagram of the structure in the embodiment where the long side of the metal embedded part is laser-cut;

[0031] Figure 3 This is a schematic diagram of the structure in the embodiment where the short side of the metal embedding part is cut out by V-cut;

[0032] Figure 4 This is a schematic diagram of the lateral structure of the metal embedded part after the plate is separated in the embodiment;

[0033] Figure 5 This is a schematic diagram of the stacked board structure in the embodiment where the circuit boards are pressed together;

[0034] Figure 6 This is a schematic diagram of the circuit board structure after lamination in the embodiment. Detailed Implementation

[0035] Numerous specific details are set forth in the following description to provide a thorough understanding of the invention; however, the invention may also be implemented using other variations or substitutions. Therefore, other possible implementations that can be discerned by those skilled in the art based on the embodiments described herein are all within the scope of protection of this invention.

[0036] Example 1

[0037] Example 1 relates to a method for fabricating a metal embedded component for a circuit board. For example... Figure 1 As shown, the preparation method of the metal embedded part in Example 1 includes the following steps: material cutting → leveling → drilling → laser cutting → first grinding → V-cut → second grinding → FQC → packaging.

[0038] Specifically, after cutting, a metal plate 10 is obtained for making the metal embedded part 20. After the metal plate 10 is leveled, holes are drilled to process positioning holes (not shown in the figure) that serve as the positioning reference for cutting. The metal plate 10 / metal embedded part 20 is preferably made of copper, and its thickness can be 0.5mm to 3mm, for example 1mm.

[0039] like Figure 2 As shown, after leveling, the positioning holes are used as the cutting positioning reference to laser-cut the long side 21 of the metal embedded part 20 on the metal plate 10. The laser cutting forms a dividing groove (0.05mm to 0.1mm wide) that completely penetrates the metal plate 10, ensuring that the long sides of adjacent metal embedded parts 20 are not connected. Since the long sides of adjacent metal embedded parts 20 in the metal plate 10 are separated only by the laser-cut dividing groove, the utilization rate of the metal plate 10 can be maximized.

[0040] In this invention, when the metal plate 10 is a copper plate, the relevant parameters for laser cutting are controlled as follows:

[0041]

[0042] Among them, the cutting frequency is the output frequency of the PWM modulation signal during cutting, representing the number of times the laser emits light within 1 second; the duty cycle is the ratio of the PWM modulation signal during cutting, representing how many time units of each light emission cycle are emitted. By controlling the above laser cutting parameters, better cutting results can be achieved for copper plates of different thicknesses, especially effectively suppressing plate deformation during laser cutting.

[0043] The plate is first ground after laser cutting to remove metal slag and burrs produced by laser cutting.

[0044] After the first grinding, as Figure 3As shown, a V-cutting tool is used to cut both sides of the metal plate 10. Figure 3 (Only one side of the V-cut groove is shown in the image). The short side 22 of the metal embedding 20 is cut out from both sides, and the short side 22 retains a micro-connection portion for connection with the metal plate frame 11. Figure 4 As shown, the short side 22 of the metal embedded part 20 forms a roughly V-shaped lateral protrusion 221 due to the V-cut cutting.

[0045] Specifically, the angle of the V-cut blade is preferably 15–30°, for example, 30°; the thickness of the micro-connection (the distance between the apexes of the V-grooves on both sides) is preferably 0.1 ± 0.05 mm, more preferably 0.1 ± 0.02 mm. By carefully controlling the angle of the V-cut blade and the dimensions of the micro-connection, the metal embedded part 20 can be prevented from falling off during grinding processes and can be easily disassembled.

[0046] Specifically, if the V-cut angle is too small, it will be difficult to separate the boards after V-cutting; if the V-cut angle is too large, when the metal embedding part 20 is pressed into the circuit board, too much resin needs to be filled into the through-hole used to set the metal embedding part 20, which may lead to insufficient filling, resulting in depressions, and may also cause problems such as poor adhesion between the resin connection and the copper surface during subsequent copper plating. If the micro-connection is too thick, it is easy to cause the metal embedding part 20 to bend and deform during board separation; if it is too thin, there will be insufficient support for subsequent grinding, browning and other treatments.

[0047] A second grinding process is performed after V-cutting to remove burrs and metal slag produced during V-cutting.

[0048] Preferably, both the first and second grinding processes employ non-woven fabric brushes or nylon needle roller brushes. Due to their relatively soft properties, these brushes can suppress deformation of the metal embedding 20 during grinding. Furthermore, the feed direction of the non-woven fabric brush or nylon needle roller brush during grinding is parallel to the short side 22. This further helps to suppress deformation of the metal embedding 20 and prevent the micro-connection of the short side 22 from breaking during grinding.

[0049] After the above manufacturing steps, the metal plate 10 forms a panel structure including a metal plate frame 11 and an array of multiple metal embedded parts 20. When using the metal embedded parts 20 later, the metal embedded parts 20 can be removed from the metal plate frame 11 by simply applying a little force to the micro-connection part of the short side 22 to separate the panels.

[0050] In Example 1, the long side 21 of the metal embedded part 20 is first laser-cut. When the metal slag and burrs generated by the laser cutting are removed by the grinding plate, the short side 22 of the metal embedded part 20 has not been cut yet. Therefore, the metal embedded part 20 will not fall off or deform during the grinding process. At the same time, the metal embedded part 20 is only connected to the metal plate frame 11 on its V-cut short side 22. When the plates are separated later, the micro-connection of the short side 22 can be broken off with a little force. Therefore, the metal embedded part 20 will not have problems such as deformation or warping.

[0051] Because slender metal embeddings 20 (with an aspect ratio greater than 5:1), especially slender copper blocks, are prone to warping deformation, the preparation method of Example 1 is particularly suitable for manufacturing slender metal embeddings 20, especially slender copper blocks, based on the aforementioned advantages. The smaller the width of the copper block (e.g., ≤4mm) and the thinner the copper block (e.g., ≤0.8mm), the more necessary this processing method is to ensure that the copper block does not bend or deform. Even when the aspect ratio of the metal embedding 20 is greater than 10:1 (e.g., 15:1, 30:1), the warping deformation of the metal embedding 20 can still be well suppressed.

[0052] Example 2

[0053] Example 2 relates to a method for manufacturing a circuit board, the circuit board comprising a circuit substrate 300 and a metal embedded member 20 disposed in the circuit substrate 300; the manufacturing method includes the following steps:

[0054] Metal embedding 20 is prepared according to the preparation method of Example 1; wherein, the metal embedding 20 can be browned before pressing and use to increase the bonding force with the resin.

[0055] The metal embedded part 20 is placed into a stacked structure for fabricating the circuit board 300 and hot-pressed; wherein, during hot pressing, buffer pads 100 are respectively provided on the upper and lower sides of the stacked structure.

[0056] For example, such as Figure 5 As shown, the stacked structure includes a copper-clad laminate 310 and a prepreg 320 stacked in a predetermined order. The copper-clad laminate 310 and the prepreg 320 have through holes 311 and 321 respectively, corresponding to the positions of the metal embedded part 20. The copper-clad laminate 310 is a double-sided copper-clad laminate, including an insulating layer 310a and copper foil layers 310b disposed on opposite sides of the insulating layer 310a.

[0057] like Figure 6As shown, after hot pressing, the prepreg 320 fills the through-hole 311 of the core board, forming a resin connection portion 322 that connects to the side (including its long and short sides) of the metal embedded part 20. The metal embedded part 20 is substantially flush with the same-side surface of the circuit board 300, and the lateral protrusion 221 of the short side 22 of the metal embedded part 20 is laterally inserted into the resin connection portion 322, making the embedding of the metal embedded part 20 more stable.

[0058] As a variation of the embodiment, the circuit board 300 can also be configured with other suitable stacked structure, such as a copper foil-prepreg-copper clad laminate-prepreg-copper foil stacked structure. The present invention does not impose any particular limitation on the circuit board 300 and its stacked structure.

[0059] Preferably, the buffer pad 100 is made of a high-temperature resistant (≥200℃) silicone oil release film with a thickness of 25μm.

[0060] When the metal embedded part 20 is relatively slender, the quality requirements for the pressed product will be higher. Therefore, the selection of the cushioning material is more important. After testing, the best material for the cushioning pad 100 is a high-temperature resistant (≥200℃) silicone oil release film with a thickness of 25μm. This thickness of release film has a certain cushioning effect, and it will not be recessed into the core plate through hole 311 during pressing. It is also easy to peel off when pressed together with the prepreg 320 resin.

[0061] Furthermore, during hot pressing, aluminum sheets and steel plates can be sequentially arranged on the outside of the buffer pad 100, that is, hot pressing is performed from top to bottom in the stacked combination of steel plate-aluminum sheet-buffer pad 100-circuit board-buffer pad 100-aluminum sheet-steel plate, so as to improve the uniformity of stress and surface flatness of the circuit board.

[0062] In addition, the circuit board manufacturing method also includes steps such as grinding (removing adhesive from the board surface) after hot pressing, copper plating on the board surface, and surface circuit fabrication. The implementation of these steps can refer to existing technologies and will not be described in detail here.

[0063] While the present invention has been disclosed above with reference to specific embodiments, these embodiments are not intended to limit the scope of the invention. Any person skilled in the art can make variations / substitutions without departing from the scope of the invention; all equivalent changes made in accordance with the invention should be covered by the protection scope of the invention.

Claims

1. A method for manufacturing a metal embedded part for a circuit board, characterized in that... Includes the following steps: Cut the material to obtain a metal plate for making metal embedding parts; After the metal plate is leveled, the long side of the metal embedding is laser-cut out. The first grinding process is performed after laser cutting; The short side of the metal embedding is cut out from both sides using a V-cut blade, and the short side retains the micro-connection part to the metal plate frame; A second grinding process is performed after V-cutting; The V-cut blade has an angle of 15~30°, and the micro-connector has a thickness of 0.1±0.05mm. The aspect ratio of the metal embedded part is greater than 5:1, and the thickness of the metal plate / metal embedded part is 0.5mm~3mm.

2. The preparation method according to claim 1, characterized in that: The first and second grinding plates are made of non-woven fabric brushes or nylon needle rollers.

3. The preparation method according to claim 1, characterized in that: The metal plate / metal embedding component is made of copper.

4. A method for manufacturing a circuit board, the circuit board comprising a circuit substrate and a metal embedded member disposed in the circuit substrate; characterized in that, The preparation method includes the following steps: Metal embeddings are manufactured according to the preparation method of any one of claims 1 to 3; The metal embedded part is placed into a stacked structure for fabricating the circuit board and hot-pressed; wherein, buffer pads are respectively provided on the upper and lower sides of the stacked structure during hot pressing.

5. The preparation method according to claim 4, characterized in that: The buffer pad is made of a high-temperature resistant silicone oil release film with a thickness of 25µm.

6. The preparation method according to claim 4, characterized in that: The stacked structure includes copper-clad laminates and prepregs stacked in a predetermined order, and the copper-clad laminates and prepregs have through holes corresponding to the positions of the metal embedded parts.

7. The preparation method according to claim 4, characterized in that: During hot pressing, aluminum sheets and steel plates are sequentially placed on the outside of the buffer pad.

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