Circuit board and preparation method of metal embedded part thereof

Abstract

The invention discloses a circuit board and a preparation method of a metal embedded part of the circuit board. The preparation method of the metal embedded part comprises the following steps that cutting is conducted, and a metal plate used for manufacturing the metal embedded part is obtained; after the metal plate is subjected to leveling treatment, the long edge of the metal embedded part is obtained through laser cutting; first-time plate grinding is carried out after laser cutting; a V-cut knife is used for cutting out short edges of the metal embedded part in a double-face mode, and micro-connection parts connected with the metal plate frame are reserved on the short edges; and after V-cut cutting, carrying out second-time plate grinding. According to the preparation method, the problem that the metal embedded part falls off during board grinding can be solved, the problem of deformation of the metal embedded part can also be solved, and then the quality of the circuit board is improved.

Description

Technical Field

[0001] The present invention relates to the field of circuit boards; more particularly, to a method for preparing a circuit board and a metal embedded part thereof. Background Art

[0002] In the prior art, metal embeddings are often installed within resin-based circuit boards (e.g., FR-4 circuit boards). These metal embeddings can function as thermal and / or electrical conductive components. These metal embeddings are typically copper blocks, and common processing methods for these embeddings include V-cutting, laser cutting, and die punching.

[0003] For example, Chinese patent document CN111975220A discloses a method for processing a heat-conducting metal block, comprising the following steps: providing a metal plate for forming a plurality of heat-conducting metal blocks; laser cutting the metal plate according to the shape of the heat-conducting metal blocks to form a heat-conducting metal block panel; the heat-conducting metal block panel comprises a metal support grid, the metal support grid has a plurality of grid holes distributed in an array, the heat-conducting metal blocks are arranged in the grid holes, and there are one or more micro-segments between the heat-conducting metal blocks and the metal support grid to connect the two 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 fall off and deform during the grinding process after laser cutting. If the connection strength of the micro-joint is increased to solve the problem of falling off and deformation, it will become difficult to disassemble; if both the long and short sides are V-cut, it will be difficult to separate the panels, and the metal embedded parts will easily deform during separation; if the punching method is used, the punched edges will also warp and deform.

[0005] The above existing molding methods all lead to warping and deformation problems in the slender metal embedded parts. When such metal embedded parts are embedded in the circuit board through the pressing step, the board surface in the area where the metal embedded parts are located will become uneven, 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 purpose of the present invention is to provide a method for preparing a metal embedded part for a circuit board, so as to improve the warping and deformation problem during the production process.

[0007] In order to achieve the above main objectives, the first aspect of the present invention discloses a method for preparing a metal embedded component for a circuit board, comprising the following steps:

[0008] Cutting the material to obtain a metal plate for making metal embedded parts;

[0009] After the metal plate is leveled, the long sides of the metal embedded parts are cut out by laser;

[0010] Perform the first grinding after laser cutting;

[0011] Use a V-cut knife to cut out the short sides of the metal embedded part on both sides, and the short sides retain the micro-connection portion connected to the metal plate frame;

[0012] Perform a second grinding after V-cutting.

[0013] In the above technical solution, the long side of the metal embedded part is first laser cut. When the plate is ground to remove the metal slag and burrs generated by the laser cutting, the short side of the metal embedded part has not been cut yet, so the metal embedded part will not fall off or deform during the grinding of the plate. The metal embedded part is only connected to the metal plate frame at its V-cut short side. When the plate is subsequently separated, the micro-connection of the short side can be disconnected with a little force. The metal embedded part will not be deformed, warped or other problems. Therefore, it is particularly suitable for the production of slender metal embedded parts.

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

[0015] Furthermore, the angle of the V-cut knife is 15 to 30 degrees, and the thickness of the micro-joint portion is 0.1±0.05 mm.

[0016] In the above technical solution, by specially controlling the angle of the V-cut knife and the size of the micro-connection, it is beneficial to achieve the purpose of preventing the metal embedded parts from breaking and falling off due to the grinding plate and being easy to disassemble.

[0017] Furthermore, the first and second grinding operations are performed with non-woven brushes or nylon needle roller brushes. These brushes are relatively soft, so metal embedded parts are less likely to deform during grinding. Using needle roller brushes also helps remove metal slag and burrs from the cutting groove.

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

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

[0020] Furthermore, the metal plate / metal embedded part is made of copper.

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

[0022] Making a metal embedded part according to the above preparation method;

[0023] The metal embedded part is placed in a laminate structure for making the circuit substrate and hot pressed; wherein, during hot pressing, buffer pads are respectively provided on the upper and lower sides of the laminate structure.

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

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

[0026] According to a specific embodiment of the present invention, the laminate structure includes a copper clad core board and a prepreg laminated in a set order, and through holes are provided in the copper clad core board and the prepreg at positions corresponding to the metal embedded parts.

[0027] Furthermore, during hot pressing, an aluminum sheet and a steel plate are sequentially arranged on the outer side of the buffer pad to improve the force uniformity and surface flatness of the circuit board.

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

[0029] Figure 1 is a processing flow chart of the metal embedded parts in the embodiment;

[0030] Figure 2 2. This is a schematic diagram of the structure in which the long side of the metal embedded part is cut out by laser in an embodiment;

[0031] Figure 3 2. This is a schematic diagram of the structure in which a V-cut is used to cut out the short side of the metal embedded part in the embodiment;

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

[0033] Figure 5 2 is a schematic diagram of a laminated structure of circuit boards pressed together in an embodiment;

[0034] Figure 6 2 is a schematic diagram of the structure of the circuit board after pressing in the embodiment. DETAILED DESCRIPTION

[0035] The following description sets forth many specific details to facilitate a thorough understanding of the present invention. However, the present invention may also be implemented in other variations or alternative forms based on these details. Therefore, other possible implementations that may be known to those skilled in the art based on the embodiments described herein are all within the scope of protection of the present invention.

[0036] Example 1

[0037] Example 1 relates to a method for preparing a metal embedded part for a circuit board. Figure 1 As shown, the preparation method of the metal embedded part in Example 1 includes the following steps: 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 embedding part 20. The metal plate 10 is flattened and then drilled to form a positioning hole (not shown) that serves as a cutting positioning reference. The metal plate 10 / metal embedding part 20 is preferably made of copper and has a thickness of 0.5 mm to 3 mm, for example, 1 mm.

[0039] like Figure 2 As shown, after leveling, the long sides 21 of the metal inserts 20 are laser-cut on the metal plate 10, using the positioning holes as cutting references. The laser cutting forms a separation groove (with a width of 0.05 mm to 0.1 mm) that completely penetrates the metal plate 10, leaving the long sides of two adjacent metal inserts 20 disconnected. The long sides of two adjacent metal inserts 20 in the metal plate 10 are separated only by the laser-cut separation groove, maximizing the utilization of the metal plate 10.

[0040] In the present invention, when the metal plate 10 is a copper plate, the relevant parameters of laser cutting are controlled as shown in the following table:

[0041]

[0042] The cutting frequency is the output frequency of the PWM modulation signal during cutting, indicating the number of times the laser emits light in 1 second. The duty cycle is the ratio of the PWM modulation signal during cutting, representing the number of time units of light output during each light cycle. By controlling these laser cutting parameters, we can achieve optimal cutting results for copper plates of varying thicknesses, especially effectively suppressing plate deformation during laser cutting.

[0043] The first grinding is performed after laser cutting to remove the metal slag and burrs generated by laser cutting.

[0044] After the first grinding, if Figure 3As shown, a V-cut knife is used to cut the two side surfaces of the metal plate 10 ( Figure 3 Only one side of the surface of the V-cut groove is shown), the short side 22 of the metal embedded part 20 is cut out on both sides, and the short side 22 retains the micro-connection portion connected to the metal plate frame 11. Figure 4 As shown, the short side 22 of the metal embedding part 20 is formed into a substantially V-shaped lateral protrusion 221 by adopting V-cut cutting.

[0045] Specifically, the angle of the V-cut is preferably 15 to 30 degrees, for example, 30 degrees. The thickness of the micro-joint (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 and the dimensions of the micro-joint, the metal insert 20 can be prevented from falling off during grinding and easily removed.

[0046] Specifically, if the V-cut angle is too shallow, it will be difficult to separate the boards after the V-cut. If the V-cut angle is too large, when the metal insert 20 is pressed into the circuit board, too much resin will need to be filled into the through-holes used to accommodate the metal insert 20. This may result in incomplete filling and depressions. This can also lead to poor adhesion between the resin joint and the copper surface during subsequent copper electroplating. If the micro-joint is too thick, it can easily cause the metal insert 20 to bend and deform during separation. If it is too thin, it will not provide sufficient support for subsequent grinding, browning, and other processes.

[0047] The second grinding is performed after V-cut cutting to remove the burrs and metal slag generated by V-cut cutting.

[0048] Preferably, both the first and second grinding passes utilize a non-woven brush or a nylon needle roller. Because these brushes are relatively soft, they can prevent deformation of the metal insert 20 during grinding. Furthermore, the feed direction of the non-woven brush or nylon needle roller during grinding is parallel to the short edge 22, further minimizing deformation of the metal insert 20 and preventing breakage of the micro-connections of the short edge 22 during grinding.

[0049] After the above steps, the metal sheet 10 is formed into a panel structure comprising a metal sheet frame 11 and an array of multiple metal inserts 20. To subsequently use the metal inserts 20, simply apply force to the micro-joints of the short edges 22 to remove them from the metal sheet frame 11, thereby separating the panels.

[0050] In Example 1, the long side 21 of the metal embedding part 20 is first laser cut. When the plate is ground to remove the metal slag and burrs generated by the laser cutting, the short side 22 of the metal embedding part 20 has not been cut yet. Therefore, the metal embedding part 20 will not fall off or deform when the plate is ground. At the same time, the metal embedding part 20 is only connected to the metal plate frame 11 at its V-cut short side 22. When the plate is subsequently separated, the micro-connection of the short side 22 can be disconnected with a little force, and the metal embedding part 20 will not be deformed, warped or other problems.

[0051] Because slender metal inlays 20 (having an aspect ratio greater than 5:1), particularly slender copper blocks, are prone to warping and deformation, the preparation method of Example 1, based on the aforementioned advantages, is particularly suitable for the production of slender metal inlays 20, particularly slender copper blocks. The smaller the width of the copper block (e.g., ≤4 mm) and the thinner the copper block (e.g., ≤0.8 mm), the more desirable this processing method is to prevent the copper block from bending and deformation. Even when the aspect ratio of the metal inlay 20 is greater than 10:1 (e.g., 15:1, 30:1), warping and deformation of the metal inlay 20 can still be effectively suppressed.

[0052] Example 2

[0053] Example 2 relates to a method for preparing a circuit board, wherein the circuit board includes a circuit substrate 300 and a metal embedded part 20 disposed in the circuit substrate 300. The preparation method includes the following steps:

[0054] The metal embedding part 20 is manufactured according to the preparation method of Example 1. The metal embedding part 20 may be browned before being pressed for use to increase the bonding strength with the resin.

[0055] The metal embedded part 20 is placed in a laminate structure for manufacturing a circuit substrate 300 and hot pressed. During the hot pressing, buffer pads 100 are respectively provided on the upper and lower sides of the laminate structure.

[0056] For example, Figure 5 As shown, the laminate structure includes a copper-clad core board 310 and a prepreg 320 stacked in a predetermined order. Core board through-holes 311 and prepreg through-holes 321 are respectively provided in the copper-clad core board 310 and the prepreg 320 at positions corresponding to the metal embedded parts 20. The copper-clad core board 310 is a double-sided copper-clad core board, 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 core board through-hole 311, forming a resin connection portion 322 connected to the side edge (including its long and short sides) of the metal embedding part 20. The metal embedding part 20 and the same side surface of the circuit substrate 300 are substantially flush, and the lateral protrusions 221 of the short side 22 of the metal embedding part 20 are laterally inserted into the resin connection portion 322, making the embedding of the metal embedding part 20 more stable.

[0058] As a variation of the embodiment, the circuit substrate 300 may also be configured as other appropriate laminate structures, such as a laminate structure of copper foil-prepreg-copper clad core board-prepreg-copper foil. The present invention does not specifically limit the circuit substrate 300 and its laminate structure.

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

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

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

[0062] In addition, the preparation method of the circuit board also includes steps such as grinding the board (removing glue from the board surface) after hot pressing, copper plating on the board surface, and surface circuit production. The implementation of these steps can refer to the existing technology and will not be explained in detail.

[0063] Although the present invention has been disclosed above with reference to specific embodiments, these embodiments are not intended to limit the scope of the present invention. Any person skilled in the art may make modifications or substitutions without departing from the scope of the present invention. In other words, any equivalent modifications made in accordance with the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. A method for preparing a metal embedded part for a circuit board, characterized in that The steps include: Cutting the material to obtain a metal plate for making metal embedded parts; After the metal plate is leveled, the long sides of the metal embedded parts are cut out by laser; Perform the first grinding after laser cutting; Use a V-cut knife to cut out the short sides of the metal embedded part on both sides, and the short sides retain the micro-connection portion connected to the metal plate frame; Perform a second grinding after V-cutting.

2. The preparation method according to claim 1, wherein: The angle of the V-cut knife is 15 to 30 degrees, and the thickness of the micro-joint portion is 0.1±0.05 mm.

3. The preparation method according to claim 1, wherein: The first grinding plate and the second grinding plate adopt non-woven brushes or nylon needle roller grinding brushes.

4. The preparation method according to claim 1, wherein: The aspect ratio of the metal embedded part is greater than 5:

1.

5. The preparation method according to claim 1, wherein: The thickness of the metal plate / metal embedded part is 0.5mm to 3mm.

6. The preparation method according to claim 1, wherein: The metal plate / metal embedded part is made of copper.

7. A method for preparing a circuit board, the circuit board comprising a circuit substrate and a metal embedded part arranged in the circuit substrate; characterized in that: The preparation method comprises the following steps: Making a metal embedded part according to the preparation method according to any one of claims 1 to 6; The metal embedded part is placed in a laminate structure for making the circuit substrate and hot pressed; wherein, during hot pressing, buffer pads are respectively provided on the upper and lower sides of the laminate structure.

8. The preparation method according to claim 7, characterized in that: The buffer pad adopts a high-temperature resistant silicone oil-containing release film with a thickness of 25 μm.

9. The preparation method according to claim 7, characterized in that: The laminate structure comprises a copper clad core board and a prepreg laminated in a set order, and through holes are provided in the copper clad core board and the prepreg at positions corresponding to the metal embedded parts.

10. The preparation method according to claim 7, characterized in that: During hot pressing, an aluminum sheet and a steel plate are sequentially arranged on the outer side of the buffer pad.

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