High heat dissipation copper buried pipe circuit board

Abstract

The application relates to a high-heat-dissipation buried copper pipe circuit board, which comprises a substrate and a capillary copper pipe fixed in the substrate, the capillary copper pipe is horizontally arranged in an inner layer of the substrate, and the capillary copper pipe has the following specifications: an outer diameter of 0.15-0.8 mm, an inner diameter of 0.05-0.6 mm, and a pipe wall thickness of 0.05-0.1 mm. The circuit board is a circuit board with a horizontally arranged capillary copper pipe embedded in the inside, the heat dissipation amount and reliability are improved, and the scene demand of high reliability is met.

Description

Technical Field

[0001] This application relates to circuit board manufacturing technology, specifically to a high heat dissipation buried copper tube circuit board. Background Technology

[0002] With the rapid development of science and technology, traditional heat dissipation solutions can no longer meet the heat dissipation requirements of high reliability scenarios such as civil aerospace and military industries. The market demand for products that can meet both high heat dissipation and high reliability is increasing. With the development of civil aerospace and low-altitude economy, there is an urgent need to invent a high heat dissipation PCB solution.

[0003] For electronic devices, heat transfer typically occurs through three methods: conduction, radiation, and convection. Common PCB heat dissipation solutions include: vertical via holes, filling vertical via holes with high thermal conductivity resin, increasing the copper thickness of the via holes, increasing the via hole density, localized copper embedding, metal substrate cooling, external heat dissipation devices such as heat sink fins, liquid cooling pipes, cooling fans, ion fans, etc., increasing the copper thickness of the heat dissipation layer, embedding copper fins within the PCB, increasing the number of current-carrying layers to reduce thermal resistance and thus reduce heat generation, external heat sink plates, and internal thermally conductive metal sandwich layers. All of these commonly used heat dissipation solutions suffer from insufficient heat dissipation. Utility Model Content

[0004] To overcome the above-mentioned defects, this application provides a high heat dissipation embedded copper tube circuit board, which is a circuit board with horizontally arranged capillary copper tubes embedded inside, which improves heat dissipation and reliability, and meets the requirements of scenarios with high reliability.

[0005] The technical solution adopted by this application to solve its technical problem is:

[0006] A high heat dissipation buried copper tube circuit board includes a substrate 10 and a capillary copper tube 11 fixed in the substrate 10. The capillary copper tube 11 is horizontally arranged in the inner layer of the substrate 10. The specifications of the capillary copper tube 11 are: outer diameter 0.15mm-0.8mm, inner diameter 0.05mm-0.6mm, and tube wall thickness 0.05-0.1mm.

[0007] Optionally, the surface of the capillary copper tube is coated with a semi-cured resin, the thickness of which is 8-16 μm.

[0008] Optionally, at least one set of microfluidic heat dissipation channels formed by capillary copper tubes is embedded in the substrate, and through holes are opened in the substrate, with the distance between the through holes and the capillary copper tubes being >0.35mm.

[0009] Optionally, the substrate is formed by laminating a first multilayer board, a second multilayer board, and a prepreg. Half-grooves for embedding tubes are processed on both the first multilayer board and the second multilayer board. When the first multilayer board and the second multilayer board are joined together, the two half-grooves are spliced ​​together to form a receiving groove, and the capillary copper tube is placed horizontally in the receiving groove.

[0010] Optionally, the half-groove is machined using a ball end mill, the diameter of which is 0.1 mm ± 0.02 mm larger than the outer diameter of the capillary copper tube, and the depth of the half-groove is 45% ± 2% of the outer diameter of the capillary copper tube.

[0011] Optionally, the thickness of the prepreg is 50±10μm.

[0012] Optionally, the substrate is formed by laminating a first multilayer board, a second multilayer board, a prepreg and a copper-free substrate, and a receiving groove is formed on the copper-free substrate, with the capillary copper tube placed in the receiving groove.

[0013] Optionally, the thickness of the copper-free substrate is less than the outer diameter of the capillary copper tube, and the difference between the two is 0.2 mm ± 0.02 mm.

[0014] Optionally, the receiving groove is a U-shaped groove, and the opening diameter of the U-shaped groove is 0.1 mm ± 0.01 mm larger than the outer diameter of the capillary copper tube.

[0015] Optionally, the surface of the copper-free substrate is coated with resin, and the resin coating thickness is 20±2μm.

[0016] The beneficial effects of this application are as follows: This circuit board is a circuit board with horizontally arranged capillary copper tubes embedded inside, which improves heat dissipation and reliability. It is a high-heat-dissipation and high-reliability printed circuit board to meet the needs of high-reliability scenarios. Compared with traditional heat dissipation methods, it can improve heat dissipation efficiency by 50-70% and control the overall temperature of the circuit board at about 30-50℃. For high-density, small-space, high-heat-generating equipment applications, it solves the problem of needing external, large-sized heat dissipation devices. While ensuring effective heat dissipation, it can greatly reduce the size of the printed circuit board. That is, this circuit board can replace the bulky external heat exchange device, further saving equipment space. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the circuit board structure in Embodiment 1 of this application;

[0018] Figure 2 This is a schematic diagram of the multilayer board structure in Embodiment 1 of this application;

[0019] Figure 3 This is a schematic diagram of the structure of the multilayer board after dry film in Embodiment 1 of this application;

[0020] Figure 4 This is a schematic diagram of the structure of the multilayer board after single-sided etching in Embodiment 1 of this application;

[0021] Figure 5 This is a schematic diagram of the structure of the multilayer plate after milling in Embodiment 1 of this application;

[0022] Figure 6 This is a schematic diagram of the structure of the semi-finished plate in Embodiment 1 of this application;

[0023] Figure 7 This is a schematic diagram of the circuit board structure in Embodiment 2 of this application;

[0024] Figure 8 This is a schematic diagram of the structure of the multilayer board in Embodiment 2 of this application;

[0025] Figure 9 This is a schematic diagram of the structure of the multilayer board after dry film etching in Embodiment 2 of this application;

[0026] Figure 10 This is a schematic diagram of the structure of the copper-free substrate after processing in Embodiment 2 of this application;

[0027] Figure 11 This is a schematic diagram of the structure without a copper substrate after embedding a copper tube in Embodiment 2 of this application;

[0028] Figure 12 This is a schematic diagram of the structure of the copper-free substrate after hot melting in Embodiment 2 of this application;

[0029] Figure 13 This is a schematic diagram of the structure of the semi-finished plate in Embodiment 2 of this application;

[0030] In the figure: 10-substrate, 11-capillary copper tube, 12-through hole, 20-first multilayer board, 21-half-groove, 22-photosensitive dry film, 30-second multilayer board, 40-prepreg, 50-copper-free substrate, 51-accommodating groove, 60-semi-finished board. Detailed Implementation

[0031] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the embodiments described in this application are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0032] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such uses of the terms can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0033] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0034] Example 1: As Figure 1-13 As shown, a high-heat-dissipation embedded copper tube circuit board includes a substrate 10 and capillary copper tubes 11 fixed within the substrate 10. The capillary copper tubes 11 are horizontally arranged in the inner layer of the substrate 10. The specifications of the capillary copper tubes 11 are: outer diameter 0.15mm-0.8mm, inner diameter 0.05mm-0.6mm, and wall thickness 0.05-0.1mm. This circuit board, with its horizontally embedded capillary copper tubes, improves heat dissipation and reliability, making it a high-heat-dissipation, high-reliability printed circuit board to meet the needs of high-reliability scenarios. Compared to traditional heat dissipation methods, it can improve heat dissipation efficiency by 50-70%, controlling the overall temperature of the circuit board at around 30-50℃. For high-density, small-space, high-heat-generating equipment applications, it solves the need for external, large-sized heat dissipation devices. While ensuring effective heat dissipation, it can significantly reduce the size of the printed circuit board, meaning this circuit board can replace bulky external heat exchange devices, further saving equipment space.

[0035] The surface of the capillary copper tube is coated with a semi-cured resin with a thickness of 8-16 μm. After coating, a pre-drying treatment is performed to ensure adhesion quality and the reliability of the adhesive filling in the embedded tube half-groove.

[0036] like Figure 1 As shown, at least one set of capillary copper tubes 11 forming a microfluidic heat dissipation channel is embedded in the substrate 10. Through holes 12 are formed in the substrate 10, and the distance between the through holes 12 and the capillary copper tubes 11 is >0.35mm. In the inner layer of the substrate 10, one, two or more sets of microfluidic heat dissipation copper tubes can be horizontally arranged according to the wiring space and stacking design.

[0037] In Example 1, as Figure 1-6 As shown, the substrate 10 is formed by laminating a first multilayer board 20, a second multilayer board 30, and a prepreg 40. Both the first multilayer board 20 and the second multilayer board 30 have embedded tube semi-grooves 21 machined on them. When the first multilayer board 20 and the second multilayer board 30 are joined together, the two semi-grooves 21 are spliced ​​to form a receiving groove, and the capillary copper tube 11 is horizontally placed within the receiving groove. The stacking sequence of the substrate 10 is the first multilayer board 20, the prepreg 40, and the second multilayer board 30.

[0038] The half-groove 21 is machined using a ball end mill, the diameter of which is 0.1mm ± 0.02mm larger than the outer diameter of the capillary copper tube 11, and the depth of the half-groove 21 is 45% ± 2% of the outer diameter of the capillary copper tube 11.

[0039] The thickness of the prepreg 10 is 50±10μm. A prepreg pure adhesive layer is used for bonding in the buried pipe layer, and the thickness of the prepreg 10 is 50±10μm to ensure bonding quality and reliable filling of the buried pipe half-groove.

[0040] The fabrication method of the high heat dissipation embedded copper tube circuit board in Example 1, taking a ten-layer board as an example, is as follows: multilayer board first lamination → dry film 1 → single-sided etching → copper-free spherical milling → plasma desmearing → capillary copper tube browning → capillary copper tube embedding → riveting and second lamination → ultrasonic non-destructive testing → drilling → circuit → resin plugging → dry film → etching → AOI → solder mask → text → electroless gold plating → forming → testing → appearance inspection → copper tube input / output port processing → packaging

[0041] Specifically, the steps include the following:

[0042] Step 1: Lamination: After conventional material cutting and inner layer circuit processing, the two four-layer boards are laminated together in one step, such as... Figure 2 As shown, the first multilayer board 20, namely the L2-L5 layer board, and the second multilayer board 30, namely the L6-L9 layer board, are obtained.

[0043] Step 2: Dry film: such as Figure 3As shown, an etch-resistant photosensitive dry film 22 is attached to the L2 layer of the first multilayer board 20 and the L9 layer of the second multilayer board 30, while the L5 layer of the first multilayer board 20 and the L6 layer of the second multilayer board 30 are exposed.

[0044] Step 3: Single-sided etching: such as Figure 4 As shown, the L5 layer of the first multilayer board 20 and the L6 layer of the second multilayer board 30 are etched away using an acidic etching solution, exposing the film layer.

[0045] Step 4: Milling grooves: such as Figure 5 As shown, a semi-groove 21 for embedded tubes is machined on the exposed film layer of the first multilayer board 20 and the second multilayer board 30. The semi-groove is milled by ball end mill in two steps. The first step is rough milling, and the depth controlled is 0.1 mm less than the depth of the second step. The second step is finish milling, in which a brand new end mill is used for finish milling to the preset depth. After the milling is completed, the depth of the semi-groove is 100% checked and the depth accuracy is controlled within ±0.05 mm.

[0046] Step 5: Cleaning: Perform plasma cleaning on the processed embedded pipe half-groove 21 to remove adhesive and ensure that the resin in the half-groove 21 is bonded and avoids delamination;

[0047] Step 6: Treatment of capillary copper tube 11: After sealing and browning the capillary copper tube 11, apply semi-cured resin coating with a thickness of 8-16μm. After coating, pre-dry the tube.

[0048] Step 7: Embedded copper tube: Stack the first multilayer board 20 and the second multilayer board 30, and connect the two half-grooves 21 to form a receiving groove. Place the capillary copper tube 11 horizontally in the receiving groove, and place the prepreg 40 between the first multilayer board 20 and the second multilayer board 30.

[0049] Step 8: Riveting: The first multilayer board 20 and the second multilayer board 30 of the pre-embedded capillary copper tube 11 are riveted together by electromagnetic thermofusion using rivets;

[0050] Step 9: Pressing: As shown Figure 6 As shown, a vacuum press is used to press the riveted first multilayer board 20, second multilayer board 30, outer prepreg and outer copper foil layer to form a semi-finished board 60, and the outer copper foil layer is L1 and L10.

[0051] Step 10: Inspection: Perform 100% ultrasonic scanning inspection on the semi-finished plate 60 to ensure that the resin at the embedded pipe position is fully filled and the copper pipe is reliably bonded.

[0052] Step 11: Post-processing: such as Figure 1As shown, the semi-finished board 60 after lamination is subjected to post-processing such as drilling through holes to obtain the finished circuit board. The drilling program setting needs to avoid the buried pipe area, and the distance between the through hole 12 and the buried pipe is designed to be >0.35mm. After drilling, the buried pipe position needs to be inspected by X-ray.

[0053] Step 12: Before packaging the circuit boards that have passed the appearance inspection, cut the access ports at both ends of the embedded tube that are reserved at the outer perimeter of the circuit board by more than 30mm, and then solder the cut ports to connect the devices.

[0054] Example 2: Figure 7-13 As shown, the substrate 10 is formed by laminating a first multilayer board 20, a second multilayer board 30, a prepreg 40, and a copper-free substrate 50. A receiving groove 51 is formed on the copper-free substrate 50, and the capillary copper tube 11 is placed within the receiving groove 51. The stacked structure of the substrate 10 is the first multilayer board 20, the prepreg 40, the copper-free substrate 50, the prepreg 40, and the second multilayer board 30.

[0055] like Figure 11 As shown, the thickness of the copper-free substrate 50 is less than the outer diameter of the capillary copper tube 11, and the difference between the two is 0.2mm ± 0.02mm. The processing of the copper-free substrate requires the reservation of a hot melt block and four corner-aligned concentric circle modules to ensure that the expansion and contraction of the buried tube position is controlled.

[0056] like Figure 10-11 As shown, the receiving groove 51 is a U-shaped groove, and the opening diameter of the U-shaped groove is 0.1mm ± 0.01mm larger than the outer diameter of the capillary copper tube 11. Space is reserved for filling with adhesive, and the bottom of the U-shaped groove needs to be pierced.

[0057] The copper-free substrate 50 is coated with resin with a thickness of 20±2μm. After the copper-free substrate 50 is coated with resin, it is baked under the following conditions: temperature 100±5℃ and time 90±10min, until it reaches a semi-cured state.

[0058] The manufacturing method of the high heat dissipation circuit board in Example 2, taking an eight-layer board as an example, is as follows: material cutting → inner layer → one-time lamination → dry film 1 → etching → copper-free substrate grooving (double-sided controlled depth milling) → copper-free substrate resin coating semi-curing → copper tube browning treatment → embedded tube embedding in copper-free substrate → vacuum lamination → drilling → electroplating → dry film 2 → etching → AOI → solder mask → text → molding → testing → copper tube input / output port processing → final inspection → packaging

[0059] Specifically, the steps include the following:

[0060] Step 1: Lamination: After conventional material cutting and inner layer circuit processing, the two four-layer boards are laminated together in one step, such as... Figure 8As shown, the first multilayer board 20, namely the L1-L4 layer board, and the second multilayer board 30, namely the L5-L8 layer board, are obtained.

[0061] Step 2: Drying and Etching: as shown Figure 9 As shown, an anti-etching photosensitive dry film 22 is attached to the first multilayer board 20 and the second multilayer board 30 after one lamination, and L5 / L6 layer circuits are etched.

[0062] Step 3: Copper-free substrate processing: such as Figure 10 As shown, the copper-free substrate 50 is slotted on both sides to form the receiving groove 51. The specifications of the copper-free substrate 50 are: the thickness is 0.2mm smaller than the diameter of the buried tube; the material is the same as the substrate model.

[0063] The receiving groove 51 is a U-shaped groove: its diameter is 0.1mm larger than the embedded copper tube (to reserve space for filling glue), and the bottom of the U-shaped groove needs to be scooped through;

[0064] Double-sided depth control blind milling: Pineapple-shaped fine-tooth cutter rough milling + ball end mill double-sided depth control finish milling.

[0065] like Figure 11 As shown, in this embodiment: the capillary copper tube 11 has a diameter of 0.5 mm, the copper-free substrate 50 has a diameter of 0.3 mm, the opening diameter of the U-shaped groove is 0.6 mm (0.1 mm larger than the diameter of the buried copper tube), and the bottom dimension of the U-shape is 0.4 mm. The machining tolerance of the above dimensions is ±0.075.

[0066] Double-sided controlled-depth machining of the U-shaped groove ensures that the buried pipe can be effectively and accurately fixed to prevent pipe displacement;

[0067] Step 4: Resin Coating: Coat the processed U-shaped embedded tube groove copper-free substrate 50 with resin, and pre-bake the coated resin to achieve a semi-cured state; the resin coating thickness is 20±2μm. Pre-bake the coated resin at 100℃ for 90 minutes to achieve a semi-cured state.

[0068] Step 5: Treatment of capillary copper tube 11: After sealing and browning the capillary copper tube 11, apply semi-cured resin coating with a thickness of 8-16μm, and pre-dry after coating.

[0069] Step 6: Embed the copper tube: such as Figure 11 As shown, the browned capillary copper tube 11 is embedded into a U-shaped buried tube groove coated with semi-cured resin. Semi-cured sheets 40 are stacked on both sides of the copper-free substrate 50. A hot melt magnetic head is used to heat and melt the resin to cure the buried tube position, in preparation for subsequent buried tube layer riveting and lamination.

[0070] Step 7: Pressing: As shown Figure 12As shown, the buried pipe layer, the first multilayer board 20 and the second multilayer board 30 are riveted and fixed, and vacuum pressing is performed using a vacuum press to form a semi-finished board 60.

[0071] Step 10: As Figure 7 As shown, drilling: The semi-finished board 60 is mechanically drilled according to the drilling program settings to ensure that the relevant functions meet the electrical conductivity requirements. The program settings for through holes must avoid the embedded tube layer, and the distance between through hole 12 and the embedded tube must be set to >0.35mm. After drilling, the embedded tube position needs to be inspected by X-ray. Then, other post-processing processes such as electroplating, dry film, and etching are performed to obtain the finished circuit board.

[0072] Step 11: Before packaging the circuit boards that have passed the appearance inspection, cut the access ports with a diameter >30mm from the outer perimeter of the circuit board at both ends of the embedded tube, and then solder the cut ports to connect the devices.

[0073] It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. Therefore, the scope of protection of this patent application shall be determined by the appended claims.

Claims

1. A high heat dissipation buried copper pipe circuit board, characterized in that: The device includes a substrate (10) and a capillary copper tube (11) fixed within the substrate (10). The capillary copper tube (11) is horizontally arranged in the inner layer of the substrate (10). The specifications of the capillary copper tube (11) are: outer diameter 0.15mm-0.8mm, inner diameter 0.05mm-0.6mm, and tube wall thickness 0.05-0.1mm.

2. The high heat dissipation buried copper pipe circuit board according to claim 1, characterized in that: The surface of the capillary copper tube (11) is coated with a semi-cured resin, the thickness of which is 8-16 μm.

3. The high heat dissipation buried copper pipe circuit board according to claim 1, characterized in that: At least one set of capillary copper tubes (11) forming a microfluidic heat dissipation channel is embedded in the substrate (10), and a through hole (12) is opened in the substrate (10), the distance between the through hole (12) and the capillary copper tube (11) is >0.35mm.

4. The high heat dissipation buried copper pipe circuit board according to claim 1, characterized in that: The substrate (10) is formed by laminating a first multilayer board (20), a second multilayer board (30) and a prepreg (40). Both the first multilayer board (20) and the second multilayer board (30) have embedded tube half-grooves (21). When the first multilayer board (20) and the second multilayer board (30) are joined together, the two half-grooves (21) are spliced ​​together to form a receiving groove. The capillary copper tube (11) is placed horizontally in the receiving groove.

5. The high heat dissipation buried copper pipe circuit board according to claim 4, characterized in that: The half-groove (21) is machined using a ball end mill, the diameter of which is 0.1 mm ± 0.02 mm larger than the outer diameter of the capillary copper tube (11), and the depth of the half-groove (21) is 45% ± 2% of the outer diameter of the capillary copper tube (11).

6. The high heat dissipation buried copper pipe circuit board according to claim 4, characterized in that: The thickness of the semi-cured sheet (40) is 50±10μm.

7. The high heat dissipation buried copper pipe circuit board according to claim 1, characterized in that: The substrate (10) is formed by laminating a first multilayer board (20), a second multilayer board (30), a prepreg (40) and a copper-free substrate (50). A receiving groove (51) is formed on the copper-free substrate (50), and the capillary copper tube (11) is placed in the receiving groove (51).

8. The high heat dissipation buried copper pipe circuit board according to claim 7, characterized in that: The thickness of the copper-free substrate (50) is less than the outer diameter of the capillary copper tube (11), and the difference between the two is 0.2 mm ± 0.02 mm.

9. The high heat dissipation buried copper pipe circuit board according to claim 7, characterized in that: The receiving groove (51) is a U-shaped groove, and the opening diameter of the U-shaped groove is 0.1mm ± 0.01mm larger than the outer diameter of the capillary copper tube (11).

10. The high heat dissipation buried copper pipe circuit board according to claim 7, characterized in that: The copper-free substrate (50) is coated with resin, and the resin coating thickness is 20±2μm.

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