FPC board with micro flow channel and manufacturing method thereof

Abstract

The application relates to an FPC plate with a micro flow channel and a manufacturing method thereof, and comprises the following steps: S1, preparing a first adhesive layer and a single-sided copper-clad first single-sided plate, laminating the first adhesive layer on the non-copper-clad side of the first single-sided plate, cutting a first heat dissipation groove at the first adhesive layer, and obtaining a medium layer; S2, laminating the medium layer on a bottom layer circuit board for lamination, and obtaining a first intermediate body; S3, etching the first intermediate body to remove the copper cladding, and obtaining a second intermediate body; S4, preparing a third adhesive layer and a top layer circuit board, laminating the third adhesive layer on the top layer circuit board, and obtaining a pre-prepared top layer plate to be laminated; S5, laminating the pre-prepared top layer plate prepared in the step S4 on the second intermediate body prepared in the step S3 for second lamination, and obtaining an FPC finished product after the lamination, wherein the first heat dissipation groove is closed by the pre-prepared top layer plate, so that the first heat dissipation groove forms a heat dissipation flow channel.

Description

Technical Field

[0001] This invention relates to the field of flexible printed circuit board (FPC) manufacturing technology, and in particular to an FPC board with microchannels and its manufacturing method. Background Technology

[0002] There are significant differences in the materials and application scenarios of rigid PCBs and flexible FPCs. Rigid PCBs use FR-4 board as the substrate, which has a thermal conductivity of about 0.3-0.4 W / m·K. Flexible circuit boards generally use polyimide as the substrate, but polyimide has an extremely low thermal conductivity of about 0.15 W / m·K. In FPCs, the polyimide substrate hardly dissipates heat. Therefore, the heat of FPCs is mainly dissipated through lateral conduction by the copper foil of the circuit layers. This characteristic of the substrate material of FPCs makes the heat dissipation path of FPCs singular and the heat dissipation efficiency very low. The heat that cannot be dissipated in time is concentrated under the chip or in local hot spots, which will lead to increased resistance, signal instability, and accelerated material aging. At the same time, under the combined effect of heat generation and airflow cooling, FPCs will experience more significant deformation and stress problems than rigid boards, affecting the reliability of the circuit board. Summary of the Invention

[0003] Therefore, it is necessary to provide an FPC board with microchannels that can solve the problem of easy collapse of microchannel circuit boards and its manufacturing method.

[0004] One embodiment of the present invention provides a method for manufacturing an FPC board with microchannels, comprising the following steps:

[0005] S1. Prepare an adhesive layer and a single-sided copper-clad first single-sided board. Press the adhesive layer onto the non-copper-clad side of the first single-sided board. Then, perform laser-controlled depth cutting grooves on the adhesive layer of the first single-sided board to cut out the first heat dissipation groove on the adhesive layer, thereby obtaining the dielectric layer to be pressed.

[0006] S2. The dielectric layer prepared in step S1 is stacked on the bottom circuit board and the first pressing is performed to obtain the first intermediate body.

[0007] S3. After lamination, the first intermediate is etched on one side to remove the copper plating on the dielectric layer of the first intermediate, and a second intermediate is obtained.

[0008] S4. Prepare the adhesive layer and the top circuit board, and press the adhesive layer onto the top circuit board to obtain the prefabricated top board to be pressed.

[0009] S5. The prefabricated top layer plate made in step S4 is stacked on the second intermediate body made in step S3, and a second pressing is performed. After pressing, an FPC board is obtained, wherein the first heat dissipation groove is closed by the prefabricated top layer plate, so that the first heat dissipation groove forms a heat dissipation channel.

[0010] Preferably, the first heat dissipation channel includes a first connecting channel, a forward channel, a second connecting channel, and a return channel connected in sequence. The first connecting channel is located at the first end of the FPC board, the second connecting channel is located at the second end of the FPC board, and both the forward channel and the return channel extend from the first end of the FPC board to the second end of the FPC board, making the first heat dissipation channel a meandering channel. A liquid inlet is provided at the end of the first connecting channel away from the forward channel, and a liquid outlet is provided at the end of the return channel away from the second connecting channel, so that both the liquid inlet and the liquid outlet are located at the first end of the FPC board.

[0011] Preferably, the distance between the liquid inlet and the liquid outlet is a spacing, and the spacing ranges from 1.8 to 2.2 mm; the width of the heat dissipation channel is 2.8 to 3.4 mm, and the height of the heat dissipation channel is 0.36 to 0.42 mm.

[0012] Preferably, the forward groove includes a first forward groove, an auxiliary curved groove, and a second forward groove connected in sequence. The two ends of the auxiliary curved groove are respectively connected to the first forward groove and the second forward groove. The end of the first forward groove away from the auxiliary curved groove is connected to the first connecting groove, and the end of the second forward groove away from the auxiliary curved groove is connected to the second connecting groove.

[0013] Preferably, the auxiliary bend includes a first auxiliary groove, a second auxiliary groove, and a third auxiliary groove connected in sequence. The two ends of the second auxiliary groove are respectively connected to the first auxiliary groove and the third auxiliary groove. The end of the first auxiliary groove away from the second auxiliary groove is connected to the first connecting groove. The end of the third auxiliary groove away from the second auxiliary groove is connected to the second connecting groove.

[0014] Preferably, the first auxiliary groove and the third auxiliary groove extend toward the direction close to the return groove, such that the second auxiliary groove is located between the forward groove and the return groove.

[0015] Preferably, the extension directions of the first forward groove, the second forward groove, the second auxiliary groove, and the return groove are all parallel to each other; the extension directions of the first connecting groove and the second connecting groove are parallel to each other.

[0016] Preferably, in step S4, after the third adhesive layer is pressed onto the top circuit board, a second heat dissipation groove is cut out on the third adhesive layer. The shape and size of the second heat dissipation groove match the shape and size of the first heat dissipation groove, so that the first heat dissipation groove and the second heat dissipation groove are aligned and overlapped to form a heat dissipation channel.

[0017] An FPC board with microchannels is also provided, which is manufactured using the FPC board manufacturing method described above, and the FPC board has heat dissipation channels.

[0018] Preferably, the heat dissipation channel is a meandering channel, which has an inlet and an outlet, with a distance of 2 mm between the inlet and the outlet; the width of the heat dissipation channel is 3 mm, and the height of the heat dissipation channel is 0.4 mm.

[0019] The method for manufacturing FPC circuit boards of the present invention can better prepare heat dissipation microchannels for FPC boards, thereby enabling FPC boards to have better heat dissipation performance and reliability. Attached Figure Description

[0020] The above and other objects, features, and advantages of the invention will become clearer through a more detailed description of the preferred embodiments illustrated in the accompanying drawings. The same reference numerals denote the same parts throughout the drawings, and the drawings are not intentionally drawn to scale with actual dimensions; the focus is on illustrating the gist of the invention.

[0021] Figure 1 A flowchart of a preferred embodiment of the method of the present invention;

[0022] Figure 2 This is a schematic diagram of the stacked structure of the dielectric layer in a preferred embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of the stacked structure of the first intermediate in a preferred embodiment of the present invention;

[0024] Figure 4 This is a schematic diagram of the stacked structure of the second intermediate in a preferred embodiment of the present invention;

[0025] Figure 5 This is a schematic diagram of the stacked structure of the FPC board according to a preferred embodiment of the present invention;

[0026] Figure 6 This is a schematic diagram of the shape of the heat dissipation channels distributed on the dielectric layer in a preferred embodiment of the present invention;

[0027] Figure 7 A cross-sectional view of a microchannel-equipped FPC board according to a preferred embodiment of the present invention is shown.

[0028] Figure 8This is a schematic diagram of the shape of the heat dissipation channels distributed on the dielectric layer in Embodiment 2 of the present invention;

[0029] Dielectric insulating substrate 11; dielectric copper film 12; first adhesive layer 13; bottom insulating substrate 21; bottom copper film 22; top insulating substrate 31; top copper film 32; third adhesive layer 33; first connecting groove 41; first forward groove 4101; second forward groove 4102; first auxiliary groove 41a; second auxiliary groove 41b; third auxiliary groove 41c; liquid inlet 410; forward groove 42; reflux groove 43; second connecting groove 44; liquid outlet 440. Detailed Implementation

[0030] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0031] like Figures 1-7 As shown, a method for fabricating an FPC board with microchannels is provided, comprising the following steps:

[0032] S1. Prepare a first adhesive layer 13 and a single-sided copper-clad first single-sided panel. The first single-sided panel includes a dielectric insulating substrate 11 and a dielectric copper film 12. Press the first adhesive layer 13 onto the non-copper-clad side of the first single-sided panel. Then, perform laser-controlled depth cutting grooves on the first adhesive layer 13 to cut out a first heat dissipation groove on the first adhesive layer 13, thus obtaining the dielectric layer to be pressed. By fabricating the single-sided copper-clad first single-sided panel into a dielectric layer during the manufacturing process, the dielectric microchannels are created by laser-cutting blind grooves, and the outer dielectric copper film 12 provides support for the microchannels. Laser cutting is used to perform controlled depth cutting from the adhesive surface, cutting through only the insulating substrate 11 and the first adhesive layer 13, without cutting through the outer dielectric copper film 12, and using the outer copper to form a supporting effect for the dielectric.

[0033] S2. The dielectric layer prepared in step S1 is stacked on the bottom circuit board and pressed for the first time to obtain the first intermediate body; wherein, the bottom circuit board includes a bottom insulating substrate 21 and a bottom copper film 22.

[0034] S3. After lamination, the first intermediate is etched on one side to remove the copper film 12 of the dielectric layer on the first intermediate, and a second intermediate is obtained. In this way, the dielectric and the bonding are laminated to the bottom circuit board, and the copper layer on the dielectric is removed by one-sided etching.

[0035] S4. Prepare a third adhesive layer 33 and a top circuit board, and press the third adhesive layer onto the top circuit board to obtain a prefabricated top circuit board to be pressed; prepare a third adhesive layer and a single-sided copper-clad top circuit board, and press the third adhesive layer onto the non-copper side of the single-sided copper-clad board to obtain a top circuit board to be pressed; the third adhesive layer is first attached to a carrier film and cut, and then transferred to the top circuit board, using the carrier film to support the U-shaped microchannels; the top circuit board is single-sided copper-clad, and includes a top insulating substrate 31 and a top copper film 32.

[0036] S5. The prefabricated top layer plate made in step S4 is stacked on the second intermediate body made in step S3, and a second pressing is performed. After pressing, the FPC finished product is obtained, and the fabrication of the U-shaped microchannel FPC is completed. The first heat sink is closed by the prefabricated top layer plate, so that the first heat sink forms a heat dissipation channel, and the distribution shape of the first heat sink is the same as the distribution shape of the heat dissipation channel.

[0037] This invention achieves consistent and high-quality manufacturing of the U-shaped microchannel FPC through the above-mentioned process method. The microchannel manufacturing is precise and does not deviate, resulting in the FPC board having better heat dissipation and better product reliability.

[0038] In a preferred embodiment, both the top-layer circuit board and the bottom-layer circuit board are fabricated using single-sided copper-clad laminates. In step S2, the side of the dielectric layer with the first adhesive layer faces the bottom-layer circuit board, thereby stacking the dielectric layer on the bottom-layer circuit board.

[0039] In a preferred embodiment, the first heat dissipation channel includes a first connecting channel, a forward channel, a second connecting channel, and a return channel connected in sequence. The first connecting channel is located at the first end of the FPC board, and the second connecting channel is located at the second end of the FPC board. Both the forward channel and the return channel extend from the first end of the FPC board to the second end of the FPC board, making the first heat dissipation channel a meandering channel. An inlet is provided at the end of the first connecting channel away from the forward channel, and an outlet is provided at the end of the return channel away from the second connecting channel, so that both the inlet and the outlet are located at the first end of the FPC board.

[0040] The distance between the liquid inlet and the liquid outlet is the spacing, and the spacing ranges from 1.8 to 2.2 mm; the width of the heat dissipation channel is 3 mm, and the height of the heat dissipation channel is 0.4 mm.

[0041] The inlet 410 and outlet 440 are both located on the same side of the FPC board and are close to each other. The heat dissipation channel flows from the first end to the second end of the FPC board and then back to the first end via a return flow. The liquid that has absorbed heat in the heat dissipation channel flows out from the outlet 440, which is very close to the inlet 410. This enclosed, meandering micro-heat dissipation channel allows for a large heat exchange area on the circuit board, resulting in better heat dissipation. Simultaneously, the proximity of the inlet 410 and outlet 440, with a distance ranging from 1.8 to 2.2 mm, allows the coolant entering through the inlet and exiting through the outlet to be discharged to the outside of the FPC board through a single through-hole. The coolant enters through the inlet and then flows sequentially along the first connecting groove, the forward groove, the return groove, and the second connecting groove inside the FPC board, finally exiting from the outlet at the end of the return groove, achieving efficient and active cooling of the FPC board.

[0042] Preferably, the forward groove includes a first forward groove 4101, an auxiliary bend groove, and a second forward groove 4102 connected in sequence. The two ends of the auxiliary bend groove are connected to the first forward groove 4101 and the second forward groove 4102, respectively. The end of the first forward groove 4101 away from the auxiliary bend groove is connected to the first connecting groove, and the end of the second forward groove away from the auxiliary bend groove is connected to the second connecting groove. Adding the auxiliary bend groove further increases the distribution of heat dissipation channels on the circuit board, expands the heat exchange area between the heat dissipation channels and the inner layers of the circuit board, and further enhances the heat dissipation effect.

[0043] The auxiliary bend includes a first auxiliary groove 41a, a second auxiliary groove 41b, and a third auxiliary groove 41c connected in sequence. Both ends of the second auxiliary groove are connected to the first auxiliary groove and the third auxiliary groove, respectively. The end of the first auxiliary groove furthest from the second auxiliary groove is connected to the first connecting groove, and the end of the third auxiliary groove furthest from the second auxiliary groove is connected to the second connecting groove. Preferably, the first auxiliary groove and the third auxiliary groove extend towards the direction close to the return flow groove, such that the second auxiliary groove is located between the forward groove and the return flow groove.

[0044] The extension directions of the first forward groove 4101, the second forward groove 4102, the second auxiliary groove, and the return groove are all parallel to each other; the extension directions of the first connecting groove and the second connecting groove are parallel, that is, the extension direction of the first connecting groove is the same as the extension direction of the second connecting groove, the extension direction of the forward groove is the same as the extension direction of the return groove, and the extension direction of the first connecting groove forms an angle with the extension direction of the forward groove.

[0045] In a preferred embodiment, in step S4, after the third adhesive layer 33 is pressed onto the top circuit board, a second heat dissipation groove is cut out on the third adhesive layer 33. The shape and size of the second heat dissipation groove match the shape and size of the first heat dissipation groove, so that the first heat dissipation groove and the second heat dissipation groove are aligned and overlapped to form a heat dissipation channel. The first heat dissipation groove is located in the dielectric layer, and the second heat dissipation groove is prefabricated on the top plate.

[0046] In a preferred embodiment, the first single-sided board has a first positioning hole for lamination and alignment on its edge, the bottom circuit board has a second positioning hole for lamination and alignment on its edge, and the top circuit board has a third positioning hole for lamination and alignment on its edge; the positions of the first positioning hole, the second positioning hole, and the third positioning hole correspond to each other.

[0047] An FPC board with microchannels is also provided, which is manufactured using the FPC board manufacturing method described above, and the FPC board has heat dissipation channels.

[0048] In a preferred embodiment, the heat dissipation channel has a liquid inlet and a liquid outlet, both located on the same side of the FPC board, making the heat dissipation channel a meandering type. The heat dissipation channel includes a first connecting groove, a forward groove, a return groove, and a second connecting groove connected in sequence. The end of the first connecting groove is the liquid inlet, and the end of the return groove is the liquid outlet. Both the liquid inlet and the liquid outlet are located on the same side of the FPC board.

[0049] In a preferred embodiment, there is a gap between the liquid inlet 410 and the liquid outlet 440, the gap being in the range of 1.8-2.2 mm, and preferably 2 mm.

[0050] In a preferred embodiment, the width of the heat dissipation channel is 2.8-3.4 mm, and the height of the heat dissipation channel is 0.36-0.42 mm. Preferably, the width of the heat dissipation channel is 3 mm, and the height of the heat dissipation channel is 0.4 mm.

[0051] Currently, for thinner FPC boards, due to their soft material and thinness, it is difficult to withstand high-pressure liquid circulation and complex sealing structures, making it difficult to achieve active liquid cooling microchannel heat dissipation. The preparation method of this invention can be applied to the preparation of FPC boards with a thickness of less than 0.2 mm, achieving better heat dissipation and stability.

[0052] To address the challenge of effective heat dissipation in flexible printed circuit boards (FPCs), this invention improves the manufacturing process by creating micro-heat dissipation channels within the FPC. These channels are designed in a meandering shape, ensuring product consistency while allowing for the distribution of these meandering micro-heat dissipation channels within the FPC. By circulating coolant through these tiny channels, heat dissipation efficiency is enhanced. This embedded microchannel heat dissipation technology achieved a heat flux density of up to 340 W / cm² in experiments. This FPC, with its strong heat dissipation capabilities and high product reliability, holds great promise for applications in high-performance chips and high-power devices.

[0053] Example 2

[0054] like Figure 8 As shown, in this embodiment, the first connecting groove 41 also includes a curved extension groove, and the liquid inlet 410 is located at the end of the extension groove. Preferably, the extension direction of the extension groove is the same as the extension direction of the return groove 43. The extension groove on the first connecting groove 41 allows the liquid inlet 410 and the liquid outlet 440 to be positioned more flexibly together, without being restricted by the distribution of circuit board components.

[0055] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A method for manufacturing an FPC board with microchannels, characterized in that, Includes the following steps: S1. Prepare a first adhesive layer and a single-sided copper-clad first single-sided board. Press the first adhesive layer onto the non-copper-clad side of the first single-sided board. Then, perform laser-controlled depth cutting grooves on the first adhesive layer to cut out the first heat dissipation groove on the first adhesive layer, thereby obtaining the dielectric layer to be pressed. S2. The dielectric layer prepared in step S1 is stacked on the bottom circuit board and the first pressing is performed to obtain the first intermediate body. S3. After lamination, the first intermediate is etched on one side to remove the copper plating on the dielectric layer of the first intermediate, and a second intermediate is obtained. S4. Prepare the third adhesive layer and the top circuit board, and press the third adhesive layer onto the top circuit board to obtain the prefabricated top board to be pressed. S5. The prefabricated top layer plate made in step S4 is stacked on the second intermediate body made in step S3, and a second pressing is performed. After pressing, an FPC board is obtained, wherein the first heat dissipation groove is closed by the prefabricated top layer plate, so that the first heat dissipation groove forms a heat dissipation channel.

2. The method for manufacturing an FPC board as described in claim 1, characterized in that, The first heat dissipation channel includes a first connecting channel, a forward channel, a second connecting channel, and a return channel connected in sequence. The first connecting channel is located at the first end of the FPC board, and the second connecting channel is located at the second end of the FPC board. The forward channel and the return channel both extend from the first end of the FPC board to the second end of the FPC board, making the first heat dissipation channel a meandering channel. A liquid inlet is provided at the end of the first connecting channel away from the forward channel, and a liquid outlet is provided at the end of the return channel away from the second connecting channel, so that the liquid inlet and the liquid outlet are both located at the first end of the FPC board.

3. The method for manufacturing an FPC board as described in claim 2, characterized in that, The distance between the liquid inlet and the liquid outlet is the spacing, and the spacing ranges from 1.8 to 2.2 mm; the width of the heat dissipation channel is 2.8 to 3.4 mm, and the height of the heat dissipation channel is 0.36 to 0.42 mm.

4. The method for manufacturing an FPC board as described in claim 3, characterized in that, The forward groove includes a first forward groove, an auxiliary bend groove, and a second forward groove connected in sequence. The two ends of the auxiliary bend groove are respectively connected to the first forward groove and the second forward groove. The end of the first forward groove away from the auxiliary bend groove is connected to the first connecting groove, and the end of the second forward groove away from the auxiliary bend groove is connected to the second connecting groove.

5. The method for manufacturing an FPC board as described in claim 4, characterized in that, The auxiliary bend includes a first auxiliary groove, a second auxiliary groove, and a third auxiliary groove connected in sequence. The two ends of the second auxiliary groove are respectively connected to the first auxiliary groove and the third auxiliary groove. The end of the first auxiliary groove away from the second auxiliary groove is connected to the first connecting groove. The end of the third auxiliary groove away from the second auxiliary groove is connected to the second connecting groove.

6. The method for manufacturing an FPC board as described in claim 5, characterized in that, The first auxiliary groove and the third auxiliary groove extend toward the direction close to the return groove, such that the second auxiliary groove is located between the forward groove and the return groove.

7. The method for manufacturing an FPC board as described in claim 6, characterized in that, The extension directions of the first forward groove, the second forward groove, the second auxiliary groove, and the return groove are all parallel to each other; the extension directions of the first connecting groove and the second connecting groove are parallel to each other.

8. The method for manufacturing an FPC board as described in claim 5, characterized in that, In step S4, after the third adhesive layer is pressed onto the top circuit board, a second heat dissipation groove is cut out on the third adhesive layer. The shape and size of the second heat dissipation groove match the shape and size of the first heat dissipation groove, so that the first heat dissipation groove and the second heat dissipation groove are aligned and overlapped to form a heat dissipation channel.

9. An FPC board with microchannels, characterized in that, The FPC board is manufactured using the manufacturing method of any one of claims 1-8, and the FPC board has heat dissipation channels.

10. The FPC board as described in claim 9, characterized in that, The heat dissipation channel is a meandering channel, which has an inlet and an outlet, with a distance of 2 mm between the inlet and the outlet; the width of the heat dissipation channel is 3 mm, and the height of the heat dissipation channel is 0.4 mm.

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