Circuit board

Abstract

The utility model discloses a circuit board. The circuit board comprises an insulating substrate and a metal embedded part, wherein the metal embedded part is arranged in an accommodating hole of the insulating substrate; wherein the hole wall of the accommodating hole is provided with a metal coating, the accommodating hole is filled with a metal connecting part for connecting the metal coating and the metal embedded part, and the metal connecting part is made of metal slurry; the circuit board is provided with a first surface and a second surface which are opposite, the first surface is provided with a first surface metal layer, and the second surface is provided with a second surface metal layer; the first surface metal layer comprises a heating element mounting part which is in heat conduction connection with the metal embedded part and a first surface circuit which is electrically isolated from the heating element mounting part, and the second surface metal layer comprises a heat dissipation part which is in heat conduction connection with the metal embedded part. According to the utility model, the metal connecting part made of the metal slurry is arranged in the metalized accommodating hole to fix the metal embedded part, so that the connection reliability of the metal embedded part and the insulating substrate can be enhanced.

Description

Technical Field

[0001] This utility model relates to the field of circuit boards; more specifically, it relates to a circuit board with metal embedded parts. Background Technology

[0002] To achieve electrical and / or thermal conductivity, it is often necessary to embed metal components, such as copper blocks, within circuit boards. Currently, there are two main types of structures for fixing metal embeddings within circuit boards: one involves placing the metal embedding into pre-drilled holes in the insulating core board and prepreg during the lamination process, relying on the resin in the prepreg to fill the gaps and fix the metal embedding; the other involves drilling holes in the laminated semi-finished circuit board, inserting copper blocks into the holes, and printing via-filling resin to fill the gaps and fix the metal embedding. After the metal embedding is fixed, multiple processes are required to complete the circuit board fabrication.

[0003] The metal embedded fixing structure using the above-mentioned existing technology is prone to cracking due to the large difference in the thermal expansion coefficients of copper and resin. Under the influence of heat and stress during the production process, the difference in their thermal expansion / contraction is large, which poses a risk to the quality of the final product. Utility Model Content

[0004] In view of the shortcomings of the prior art, the main purpose of this utility model is to provide a circuit board that can improve the reliability of the connection between the metal embedded part and the insulating substrate.

[0005] To achieve the aforementioned main objectives, this utility model discloses a circuit board, comprising an insulating substrate and a metal embedded member, wherein the metal embedded member is disposed within a receiving hole in the insulating substrate; wherein:

[0006] The wall of the receiving hole is provided with a metal plating layer, and the receiving hole is filled with a metal connecting part that connects the metal plating layer and the metal embedded part. The metal connecting part is made of metal paste.

[0007] The circuit board has a first surface and a second surface, the first surface is provided with a first surface metal layer, and the second surface is provided with a second surface metal layer; the first surface metal layer includes a heating element mounting portion that is thermally connected to the metal embedded part and a first surface line that is electrically isolated from the heating element mounting portion, and the second surface metal layer includes a heat dissipation portion that is thermally connected to the metal embedded part.

[0008] Furthermore, the metal embedding component is a copper block, and the metal paste is a copper paste.

[0009] According to a specific embodiment of the present invention, the metal embedded part is configured to penetrate the insulating substrate, and the heating element mounting part and the heat dissipation part are both directly thermally connected to the metal embedded part.

[0010] Furthermore, both the heating element mounting portion and the heat dissipation portion are configured to cover the metal connecting portion and the metal embedded part.

[0011] According to another specific embodiment of the present invention, an insulating layer is provided between the metal embedded part and the first surface metal layer, and the heating element mounting part is provided with a metal heat-conducting hole that penetrates the insulating layer and is thermally connected to the metal embedded part.

[0012] Furthermore, when viewed along the thickness direction of the circuit board, the heating element mounting portion is located within the outline of the metal embedded part, and the first surface line partially overlaps with the metal embedded part.

[0013] Furthermore, the metal heat-conducting holes are completely filled with metal heat-conducting material.

[0014] Optionally, the second surface metal layer is provided with a second surface line that is electrically isolated from the heat dissipation portion. The second surface line and the first surface line can be electrically connected via conductive vias penetrating the insulating substrate.

[0015] For example, the insulating substrate includes one or more insulating core boards, and the multiple insulating core boards are connected by prepreg.

[0016] The technical solution of this utility model has the following beneficial effects:

[0017] In this invention, the walls of the receiving holes in the insulating substrate are provided with a metal plating layer, and the receiving holes are filled with a metal connecting part that connects the metal plating layer and the metal embedded part. The metal connecting part is made of metal paste, forming a connection structure of metal plating layer-metal connecting part-metal embedded part. The metal connecting part made of metal plating layer and metal paste plays a transition buffer role between the insulating substrate and the metal embedded part, reducing the risk caused by the large difference in the coefficient of thermal expansion between the insulating substrate and the metal embedded part. This improves the connection reliability between the metal embedded part and the insulating substrate and greatly reduces the problem of cracks between them due to heat and stress in subsequent processes.

[0018] Furthermore, the two opposite surfaces of the circuit board are respectively provided with a heating element mounting part and a heat dissipation part that are thermally connected to the metal embedded part. The heat generated when the heating element is working can be conducted to the heat dissipation part through the heating element mounting part and the metal embedded part, so that the circuit board can quickly dissipate heat from the heating element.

[0019] To more clearly illustrate the purpose, technical solution, and advantages of this utility model, the following detailed description is provided in conjunction with the accompanying drawings and specific embodiments. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the circuit board of embodiment 1 of this utility model;

[0021] Figure 2 This is a schematic diagram of the structure in Example 1 where a metal embedded part is placed in the metallized receiving hole;

[0022] Figure 3 This is a schematic diagram of the structure in Example 1 where a metal connection is fabricated within a metallized accommodating hole;

[0023] Figure 4 This is a schematic diagram of the structure of embodiment 2 of the circuit board of this utility model. Detailed Implementation

[0024] The technical solution of this utility model is described in detail below with reference to specific embodiments. However, this utility model can also be implemented in other variations based on this description. Therefore, the protection scope of this utility model is not limited to the specific embodiments disclosed below.

[0025] Example 1

[0026] like Figure 1 As shown, the circuit board of Embodiment 1 includes an insulating substrate 10 and a metal embedded member 21, the metal embedded member 21 being disposed in the receiving hole 11 of the insulating substrate 10 (see... Figure 2 Specifically, the insulating substrate 10 may include one or more insulating core boards. The multiple insulating core boards can be connected using prepregs, for example, by a pressing step to cure the prepregs, thereby achieving the connection between the multiple insulating core boards. The insulating core board may be a double-sided copper-clad FR-4 insulating core board, but this invention is not limited to this.

[0027] In this invention, the metal embedded part 21 can specifically be a copper block; the receiving hole 11 is a metallized receiving hole, and its hole wall is provided with a metal plating layer 12, which can specifically be a copper plating layer. The receiving hole 11 is filled with a metal connecting part 22 that connects the metal plating layer 12 and the metal embedded part 21. The metal connecting part 22 is made of metal paste, which can be copper paste or silver paste, with copper paste being preferred.

[0028] The circuit board has a first surface and a second surface. The first surface of the circuit board is provided with a first surface metal layer 32, and the second surface is provided with a second surface metal layer 33. The first surface metal layer 32 and the second surface metal layer 33 can typically be or include copper foil layers with flat surfaces. Specifically, the first surface metal layer 32 includes a heat-generating element mounting portion 322 that is thermally connected to the metal embedded member 21 and a first surface line 321 that is electrically isolated from the heat-generating element mounting portion 322. The second surface metal layer 33 includes a heat-dissipating portion 332 that is thermally connected to the metal embedded member 21.

[0029] Furthermore, the second surface metal layer 33 may also include a second surface line 331 electrically isolated from the heat dissipation portion 332, and the first surface line 321 and the second surface line 331 may be electrically connected through a conductive via 34 penetrating the insulating substrate 10. As a variation of the embodiment, the second surface metal layer 33 may not have the second surface line 331, and may instead be used entirely as a heat dissipation portion.

[0030] In Embodiment 1, the metal embedded part 21 is configured to penetrate the insulating substrate 10. The heating element mounting part 322 and the heat dissipation part 332 are both directly thermally connected to the metal embedded part 21 for rapid heat conduction. Preferably, the heating element mounting part 322 and the heat dissipation part 331 are both configured to cover the metal connecting part 22 and the metal embedded part 21 to fill in any possible recesses in the metal connecting part 22 as much as possible.

[0031] Furthermore, in Embodiment 1, the metal plating layer 12 on the wall of the receiving hole 11 is connected to the first surface metal layer 32 and the second surface metal layer 33, for example, to the copper surface of the heating element mounting part 322 and the heat dissipation part 332. This helps to increase the bonding force between the metal plating layer 12 and the insulating substrate 10, so that the metal plating layer 12 and the insulating substrate 10 are reliably bonded, thereby improving the connection reliability between the metal embedded part 21 and the insulating substrate 10.

[0032] The following combination Figure 2 and Figure 3 An exemplary method for manufacturing a circuit board in Example 1 of the specification.

[0033] like Figure 2As shown, firstly, receiving holes 11 and through holes 13 are machined in an insulating substrate 10 with a copper foil layer 31 on its surface. Then, a first full-board copper plating is performed to form a metal plating layer 12 on the hole wall of the receiving hole 11 and a bottom copper layer 341 for conductive vias 34 on the hole wall of the through hole 13 (the copper foil layer 31 is also thickened). After the first full-board copper plating, a micro-adhesive film 101 covering the receiving hole 11 is first set on the bottom surface of the insulating substrate 10. Then, the metal embedding part 21 is placed into the receiving hole 11, and the adhesiveness of the micro-adhesive film 101 is used to pre-fix the metal embedding part 21. The gap between the metal embedding part 21 and the metal plating layer 12 can be controlled between 0.05 mm and 0.2 mm, for example, 0.1 mm.

[0034] like Figure 3 As shown, after the metal embedded part 21 is pre-fixed, metal paste is filled into the pores of the receiving hole 11 and then baked and cured to obtain the metal connection part 22. Before filling the metal paste, a protective film can be applied to the upper surface of the insulating substrate 10. The protective film is laser-cut to create windows, and the window size is 0.03mm smaller than the filling gap on one side to ensure that the metal paste does not remain on the board. After curing, the protective film and micro-adhesive film 101 can be peeled off.

[0035] After baking and curing, the semi-finished circuit board undergoes a second full-board copper plating. This second full-board copper plating not only thickens the bottom copper layer 341 to form conductive vias 34, but also creates surface copper foils of a predetermined thickness on the two opposing surfaces of the circuit board. These surface copper foils cover the copper foil layer 31, the metal connection portion 22, and the metal embedded part 21, and together with the copper foil layer 31, form the first surface metal layer 32 and the second surface metal layer 33. Subsequently, the first surface metal layer 32 and the second surface metal layer 33 are etched to obtain the heating element mounting portion 322, the first surface circuit 321, the second surface circuit 331, and the heat dissipation portion 332.

[0036] Example 2

[0037] like Figure 4 As shown, in the circuit board of Embodiment 2, an insulating layer 14 is provided between the first surface metal layer 32 and the insulating substrate 10. This structure can be obtained by laminating a prepreg to form the insulating layer 14 and a copper foil layer to form the first surface metal layer 32 onto the insulating substrate 10. The second surface metal layer 33 is disposed on the surface of the insulating substrate 10 opposite to the insulating layer 14, and its heat dissipation portion 332 is configured to cover the metal connection portion 22 and the metal embedded part 21.

[0038] Preferably, when viewed along the thickness direction of the circuit board, the heating element mounting portion 322 of the first surface metal layer 32 is disposed within the contour range of the metal embedded member 21, and the first surface wiring 321 partially overlaps with the metal embedded member 21. With this structure, the wiring area of ​​the first surface wiring 321 can be increased, facilitating wiring design and promoting the miniaturization of the circuit board.

[0039] Furthermore, the heating element mounting portion 322 is provided with a plurality of metal heat-conducting holes 323 that penetrate the insulating layer 14 and are thermally connected to the metal embedded member 21. The metal heat-conducting holes 323 are preferably completely filled with a metal heat-conducting material (e.g., electroplated copper or copper paste). The copper foil layer 31 on the insulating substrate 10 connected to the insulating layer 14 can be fabricated with inner layer circuitry. This inner layer circuitry can be electrically connected to the first surface circuitry 321 and the second surface circuitry 331 through conductive vias 34.

[0040] Other descriptions of Example 2 can be found in Example 1, and will not be elaborated here.

[0041] In summary, in this utility model, the wall of the receiving hole 11 is provided with a metal plating layer 12, and the receiving hole 11 is filled with a metal connecting part 22 that connects the metal plating layer 12 and the metal embedded part 21, forming a connection structure of metal plating layer 12-metal connecting part 22-metal embedded part 21. Among them, the metal plating layer 12 and the metal connecting part 22 made of metal paste can play a transition buffer role between the insulating substrate 10 and the metal embedded part 21, reducing the risk caused by the large difference in the coefficient of thermal expansion between the insulating substrate 10 and the metal embedded part 21, thereby improving the connection reliability between the metal embedded part 21 and the insulating substrate 10, and greatly reducing the problem of cracks between the two due to heat and stress in the subsequent process.

[0042] Furthermore, the two opposite surfaces of the circuit board are respectively provided with a heating element mounting part 322 and a heat dissipation part 332 that are thermally connected to the metal embedded part 21. The heat generated when the heating element is working can be conducted to the heat dissipation part 332 through the heating element mounting part 322 and the metal embedded part 21, so that the circuit board can quickly dissipate heat from the heating element.

[0043] Although the present invention has been disclosed above with specific embodiments, any person skilled in the art may make some changes or substitutions without departing from the scope of the present invention. That is, all equivalent changes made in accordance with the present invention shall be covered by the scope of the present invention.

Claims

1. A circuit board, comprising an insulating substrate and a metal embedded member, wherein the metal embedded member is disposed within a receiving hole in the insulating substrate; characterized in that: The wall of the receiving hole is provided with a metal plating layer, and the receiving hole is filled with a metal connecting part that connects the metal plating layer and the metal embedded part. The metal connecting part is made of metal paste. The circuit board has a first surface and a second surface, the first surface is provided with a first surface metal layer, and the second surface is provided with a second surface metal layer; the first surface metal layer includes a heating element mounting portion that is thermally connected to the metal embedded part and a first surface line that is electrically isolated from the heating element mounting portion, and the second surface metal layer includes a heat dissipation portion that is thermally connected to the metal embedded part.

2. The circuit board according to claim 1, characterized in that: The metal embedding component is a copper block, and the metal paste is a copper paste.

3. The circuit board according to claim 1, characterized in that: The metal embedded part is configured to penetrate the insulating substrate, and both the heating element mounting part and the heat dissipation part are directly thermally connected to the metal embedded part.

4. The circuit board according to claim 3, characterized in that: Both the heating element mounting portion and the heat dissipation portion are configured to cover the metal connecting portion and the metal embedded part.

5. The circuit board according to claim 1, characterized in that: An insulating layer is provided between the metal embedded part and the first surface metal layer, and the heating element mounting part is provided with a metal heat-conducting hole that penetrates the insulating layer and is thermally connected to the metal embedded part.

6. The circuit board according to claim 5, characterized in that: Viewed along the thickness direction of the circuit board, the heating element mounting portion is located within the outline of the metal embedded part, and the first surface line partially overlaps with the metal embedded part.

7. The circuit board according to claim 5, characterized in that: The metal heat-conducting holes are completely filled with metal heat-conducting material.

8. The circuit board according to claim 1, characterized in that: The second surface metal layer is provided with second surface lines that are electrically isolated from the heat dissipation part.

9. The circuit board according to claim 8, characterized in that: The second surface line is electrically connected to the first surface line through a conductive via penetrating the insulating substrate.

10. The circuit board according to claim 1, characterized in that: The insulating substrate includes one or more insulating core boards, and the multiple insulating core boards are connected by a prepreg.

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