Manufacturing method of rigid-flex board with air layer

Abstract

The invention relates to a method for manufacturing a rigid-flex board with an air layer, and the method comprises the steps: S1, carrying out the pre-windowing processing of an inner glue layer bonding material of the rigid-flex board, obtaining an inner glue layer with a glue layer window, and enabling the glue layer window to correspond to the region where the air layer of a flexible board region of the rigid-flex board is located; s2, setting a soft board with an insulating layer and a circuit layer as an inner-layer soft board, performing windowing treatment on the inner-layer soft board in a waste area of the inner-layer soft board in an area corresponding to an air layer of the soft board area, and reserving a connecting rib at a windowing position; s3, the inner-layer soft boards of different lamination layers prepared in the step S2 are stacked in sequence and then laminated, and a multi-layer board is obtained; s4, performing subsequent processing on the multilayer board; and S5, laser energy is adjusted according to the thickness of one inner-layer board during laser cutting of the appearance, the connecting ribs in the waste area are removed through laser cutting, and a single finished rigid-flex circuit board is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit board manufacturing, and in particular to a method for manufacturing a rigid-flexible board with an air layer. Background Art

[0002] In rigid-flex circuit boards, in order to improve the bending performance of the product, the flexible board area that needs to be bent is often designed into an air layer structure. The current technical solution is to remove the adhesive at the air layer position in advance before laminating the multi-layer boards. After lamination, the circuits at the air layer position are not adhered to each other, thus obtaining an air layer structure.

[0003] For products with an air layer structure, if mechanical cutting is used for shape production, edge burrs will occur at the soft board position after cutting, affecting the quality of the finished product. Therefore, the hard board area of ​​the soft-rigid circuit board is cut by a gong machine, and the air layer position of the soft board area is cut by laser cutting, thereby avoiding defects such as edge burrs caused by mechanical cutting.

[0004] Since laser cutting is a thermal processing process, there will be varying degrees of carbonization on the edges during the processing. When the number of circuit layers of a multi-layer circuit board is small, the edge carbonization problem of laser cutting is within an acceptable range, and the impact on the product's appearance quality and product reliability is controllable. However, when the number of circuit layers of a multi-layer circuit board is large, for example, reaching more than ten layers, as the number of circuit layers at the air layer position increases, the cutting thickness during the shape production also increases, the laser cutting energy also increases accordingly, the thermal effect generated becomes more and more obvious, and the degree of carbonization on the edge is serious, which not only affects the product appearance, but also affects the product performance.

[0005] At present, although some technical solutions have emerged to reduce the thickness of laser cutting, such as using ink to give way, the effect is very limited, especially for laser cutting of multi-layer circuit boards with more than ten layers of circuit layers in the air layer area. There is currently no good solution to the carbonization problem. Summary of the Invention

[0006] Based on this, it is necessary to provide a method for manufacturing a rigid-flex board with an air layer.

[0007] An embodiment of the present invention provides a method for manufacturing a rigid-flex circuit board with an air layer, comprising the following steps:

[0008] S1. Pre-windowing the inner adhesive layer adhesive material of the rigid-flex board to produce an inner adhesive layer with adhesive layer windows, wherein the adhesive layer windows correspond to the area where the air layer is located in the soft board area of ​​the rigid-flex board;

[0009] S2. A flexible board having an insulating layer and a circuit layer is provided as an inner-layer flexible board. A window is opened in a waste area of ​​the inner-layer flexible board corresponding to the air layer in the flexible board area, with connecting ribs retained at the window opening positions. An inner-layer flexible board having inner-layer flexible board windows and connecting ribs is prepared for standby use. The connecting ribs between two adjacent stacked inner-layer flexible boards are sequentially staggered and spaced apart by a first spacing.

[0010] S3, sequentially stacking the inner soft boards of different layers obtained in step S2 through the inner rubber layer obtained in step S1 and pressing them together to obtain a multilayer board;

[0011] S4. Carry out subsequent processing according to product design;

[0012] S5. Laser cutting for shape processing: When laser cutting the shape, adjust the laser energy according to the thickness of an inner layer board. Laser cutting removes the connecting ribs in the waste area to obtain a single finished soft and hard combination circuit board.

[0013] Preferably, the soft board area of ​​the rigid-flex board has several layers of inner soft boards, and the several layers of inner soft boards are stacked in sequence from top to bottom.

[0014] Preferably, the area corresponding to the soft board area includes a waste area and a soft board reserved area, the connection between the waste area and the soft board reserved area is an outer cutting line, and the inner soft board window is opposite to and overlaps with the waste area.

[0015] Preferably, the connecting ribs are connected to the inner soft boards in the soft board reserved area, and the connecting ribs of the inner soft boards of any stacked layers in the soft board area do not overlap.

[0016] Preferably, the connecting ribs of the inner layer soft boards of any stack in the soft board area are arranged in parallel, and the width of the connecting ribs is greater than or equal to 4.5 mm.

[0017] Preferably, the laser parameter ranges for the laser cutting for shape processing in step S5 are: pulse frequency of 960-1000kHz, laser energy of 8-8.5W, cutting speed of 1160-1200mm / s, and number of cutting times of 18-20 times.

[0018] Preferably, the first spacing is 2 mm.

[0019] Preferably, the size of the adhesive layer window is larger than the size of the soft board reserved area.

[0020] Preferably, the edge line of the adhesive layer window is at a first distance from the outline of the flexible board reserved area, and the value range of the first distance is 2.5-3.5 mm.

[0021] Preferably, in step S4, the specific processing steps of the subsequent processing include mechanical drilling, copper electroplating, circuits, inks, and surface treatment.

[0022] The products provided by the air layer production method provided by the present invention solve the problem of severe carbonization of the edges of existing products caused by using laser cutting when the number of layers is large, improve the product appearance quality and product reliability, and realize the production of products with air layer structures with a higher number of layers. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of the preferred embodiments of the present invention shown in the accompanying drawings. The same reference numerals indicate the same parts throughout the accompanying drawings, and the drawings are not drawn to scale with actual size. The emphasis is on illustrating the subject matter of the present invention.

[0024] Figure 1 This is a schematic diagram of providing a rubber layer window in the inner rubber layer of the first embodiment of the present invention;

[0025] Figure 2 Schematic diagram of the positions of the connecting ribs of the inner flexible boards of different laminated layers according to the first embodiment of the present invention;

[0026] Figure 3 This is an overall diagram of the inner rubber layer and the inner soft board of Example 1 of the present invention when they are stacked together in sequence;

[0027] Figure 4 Schematic diagram of the top view of the rigid-flex board according to the first embodiment of the present invention;

[0028] Figure 5 for Figure 4 Schematic diagram of the cross section of the soft board retention area with sectioning along line AA';

[0029] Inner layer soft board 1; first inner layer soft board 11; second inner layer soft board 12; third inner layer soft board 13; fourth inner layer soft board 14; insulating layer 101; circuit layer 102; first window 41; second window 42; third window 43; fourth window 44; first connecting rib 51; second connecting rib 52; third connecting rib 53; fourth connecting rib 54; inner adhesive layer 2; adhesive layer window 200; first spacing L; first distance D; edge line B of the adhesive layer window; outline C of the reserved area of ​​the soft board. DETAILED DESCRIPTION

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

[0031] like Figure 1-Figure 5As shown, an embodiment of the present invention provides a method for manufacturing a rigid-flex circuit board with an air layer, comprising the following steps:

[0032] S1. Pre-windowing the inner adhesive layer of the rigid-flex board to obtain an inner adhesive layer 2 having adhesive layer windows 200. The adhesive layer windows 200 correspond to the air layer area of ​​the rigid-flex board;

[0033] S2. A soft board with an insulating layer 101 and a circuit layer 102 is set as an inner soft board 1. In the waste area of ​​the inner soft board 1 in the air layer corresponding to the soft board area, the inner soft board is windowed, and connecting ribs are retained at the window position to obtain an inner soft board with inner soft board windows and connecting ribs for standby use; wherein, the connecting ribs between two adjacent laminated inner soft boards are staggered in sequence and spaced apart by a first spacing L; preferably, the inner soft board is preformed at the air layer position, and only one connecting rib is left for fixing any inner soft board layer, and the value range of the connecting rib width is 4-7 mm, preferably, the connecting rib width is 5 mm, and the connecting rib position of each inner layer is staggered and spaced apart by a first spacing L. Spacing L, the value range of the first spacing L is greater than or equal to 2mm; it should be noted that, as known to those skilled in the art, the rigid-flex board includes a hard board area and a soft board area, and the air layer is arranged in the soft board area. Before the outer shape cutting in step S5, there is still a waste area, that is, when the outer shape cutting is performed in step S5, the area to be cut off is the waste area, and the remaining part is the soft board reserved area, and the air layer is arranged within the range of the soft board reserved area; wherein, the edge line B of the window of the adhesive layer opening 200 is a first distance D away from the outer shape line C of the soft board reserved area at the position of the air layer, and the value range of the first distance D is 2.5-3.5mm. Preferably, the first distance D is 3mm.

[0034] S3, sequentially stacking the inner layer soft boards 1 of different layers obtained in step S2 through the inner rubber layer 2 obtained in step S1 and pressing them together to obtain a multilayer board; pressing the rigid-flexible board according to the product design to form a multilayer rigid-flexible board;

[0035] S4. According to the product design, the laminated multilayer board is subjected to subsequent processing. Specifically, according to the product design, the specific processing steps for the laminated multilayer board include mechanical drilling, copper electroplating, circuit, ink, surface treatment and other processing.

[0036] S5, laser cutting for shape processing: when laser cutting the shape, the laser energy is adjusted according to the thickness of an inner layer soft board, and the laser cutting removes the connecting ribs in the waste area to obtain a single finished soft and hard circuit board. Preferably, when laser cutting the shape, the laser energy is adjusted according to the thickness of an inner layer board, and only the connecting rib position is cut to avoid severe carbonization of the edge due to excessive energy, thereby completing the shape processing of the soft board at the air layer position. The laser parameter range for laser cutting for shape processing in step S5 is: pulse frequency of 960-1000kHz, laser energy of 8-8.5w, cutting speed of 1160-1200mm / s, and number of cutting times of 18-20 times. The present invention improves the manufacturing method of the circuit board so that the laser cutting to produce the shape only needs to cut the thickness of a single layer of connecting ribs. The reduced laser cutting energy avoids quality and performance problems caused by carbonization of the edges of circuit boards with more layers.

[0037] In a preferred embodiment, the soft board area of ​​the hard-flex board has several layers of inner soft boards 1, and the several layers of inner soft boards 1 are stacked in sequence from top to bottom. Two adjacent inner soft boards 1 are bonded using an inner glue layer 2 having a glue layer window 200. The inner soft board window is directly opposite to the glue layer window 200, wherein the edge line of the inner soft board window is the outline C of the soft board reserved area, that is, the edge line B of the glue layer window 200 is a first distance D away from the edge line of the inner soft board window. Preferably, the first distance D is 3 mm.

[0038] In a preferred embodiment, the area corresponding to the soft board area includes a waste area and a soft board reserved area. The connection between the waste area and the soft board reserved area is the outer cutting line, which is the outer cutting line C of the soft board reserved area. The inner soft board window is directly opposite and overlaps with the waste area, that is, the inner soft board window is pre-made at the inner soft board 1, and only the connecting ribs are reserved.

[0039] In a preferred embodiment, the connecting ribs are connected to the inner soft boards 1 in the soft board reserved area, and the connecting ribs of the inner soft boards 1 of any stacked layers in the soft board area do not overlap.

[0040] In a preferred embodiment, the connecting ribs of the inner soft boards 1 of any stacked layers in the soft board area are arranged in parallel, and the width of the connecting ribs is greater than or equal to 4.5 mm. More preferably, the width of the connecting ribs is 5 mm.

[0041] In a preferred embodiment, the inner layer flexible board is a copper clad circuit board, and the thickness of a single layer of the inner layer flexible board is (0.16±0.01) mm.

[0042] In a preferred embodiment, the value range of the first distance L is greater than or equal to 2 mm.

[0043] In a preferred embodiment, the size of the adhesive layer window is larger than the size of the soft board reserved area. The edge of the adhesive layer window extends 3 mm into the soft board reserved area. That is, the edge of the adhesive layer window is 3 mm larger than the outline of the soft board reserved area. The edge of the adhesive layer window extends outward from the outline of the soft board reserved area by a first distance D.

[0044] It should be noted that the rigid-flex board is a multi-layer board, which is made by laminating multiple layers of inner soft boards by bonding them with adhesive materials. The multi-layer board has a rigid-flex area and a soft board area, and an air layer corresponding area is provided in the soft board area; the adjacent two layers of inner soft boards 1 of the rigid-flex board are bonded by an inner adhesive layer 2, wherein the soft board area of ​​the rigid-flex board is made by laminating multiple inner soft boards, and the multi-layer soft board is made of an inner soft board 1. The inner soft board includes an insulating dielectric layer 101 and a circuit layer 102. The circuit layer is made on the surface of the dielectric layer, and the circuit layer is made on the surface of the rigid-flex board. In the air layer corresponding area of ​​the soft board area of ​​the bonding board, the inner rubber layer of the multilayer board in the soft board area is pre-treated with a window to produce an inner rubber layer 2 with a window. The soft board area of ​​the soft-rigid bonding board uses an inner layer soft board including a dielectric layer and a circuit layer, and a circuit layer is made on the surface of the dielectric layer. In the air layer corresponding area of ​​the soft board area, the inner rubber layer of the multilayer board is subjected to a window treatment to produce an inner rubber layer with a window for standby use. Any inner layer soft board includes an insulating layer and a circuit layer, and the connecting ribs of the next layer are staggered with the connecting ribs of the adjacent upper layer. The inner layer soft board is a copper-clad circuit board, and the thickness of the inner layer soft board is the sum of the thickness of the insulating dielectric layer 101 and the circuit layer 102. The thickness of the inner layer soft board is (0.16±0.01) mm. Preferably, the thickness of a single inner layer soft board is 0.167 mm.

[0045] In a preferred embodiment, the number, width, and type of connecting ribs are adjusted based on the specific number of layers and dimensions of the rigid-flex board. The air layer fabrication method provided by this invention solves the problem of severe carbonization at the edges of existing products caused by laser cutting when there are many layers. This improves product appearance and reliability, and enables the fabrication of products with higher numbers of air layer structures.

[0046] Example 1

[0047] This embodiment is described as a case where the inner layer soft board 1 of the soft board area is composed of four stacked layers.

[0048] Before the multi-layer boards are pressed together, the inner rubber layer at the air layer position is windowed, and the window size of the rubber layer window is 3mm larger on one side than the outer line of the inner soft board. It should be noted that the outer line of the inner soft board refers to the position of the outer edge of the single circuit board product after cutting when the outer shape is processed after the circuit board is produced; the window size of the rubber layer window on one side refers to the position of the dividing line where the outer edge of the rubber layer window is located.

[0049] The inner soft board at the air layer position is preformed, and only one connecting rib is left for fixing any inner soft board layer. There are four inner soft boards in the soft board area, including a first inner soft board 11, a second inner soft board 12, a third inner soft board 13 and a fourth inner soft board 14. The inner soft board window on the first inner soft board 11 is a first window 41, and the inner soft board windows on the second inner soft board 12, the third inner soft board 13 and the fourth inner soft board 14 are respectively a second window 42, a third window 43 and a fourth window 44. The first window 41, the second window 42, The third window 43 and the fourth window 44 are opposite and overlap each other; a first connecting rib 51 is set in the first window 41, a second connecting rib 52 is set in the second window 42, a third connecting rib 53 is set in the third window 43, and a fourth connecting rib 54 is set in the fourth window 44. The width of the connecting ribs is set to 5 mm, and the positions of the first connecting rib 51, the second connecting rib 52, the third connecting rib 53 and the fourth connecting rib 54 are staggered; the connecting ribs between the inner layer soft boards of two adjacent laminated layers are staggered in sequence and spaced by a first spacing L, and the value of the first spacing L is 2 mm.

[0050] According to the product design, four inner-layer flexible boards are stacked sequentially, and two adjacent inner-layer flexible boards are bonded using an inner adhesive layer with adhesive window 200. The stacked rigid-flex boards are then pressed together to form a multi-layer rigid-flex board. The four inner-layer flexible boards are bonded using three inner adhesive layers. The resulting rigid-flex board, made by stacking four inner-layer flexible boards, has a thickness of 0.5±0.1mm. Therefore, the thickness of the laser-cut single-layer connecting ribs is approximately 0.125±0.01mm.

[0051] According to the product design, mechanical drilling, copper electroplating, circuit, ink, surface treatment and other processing processes are carried out; when laser cutting the shape, the laser energy is adjusted according to the thickness of an inner layer board, and only the connection rib position is cut to avoid severe carbonization of the edge due to excessive energy, thereby completing the shape processing of the soft board at the air layer position.

[0052] Example 2

[0053] This embodiment is described as follows: the inner layer flexible circuit board 1 in the flexible circuit board area is stacked with twelve layers.

[0054] Using the air layer fabrication method of the present invention, a twelve-layer rigid-flex PCB with 12 circuit layers in the air layer area was fabricated. The thickness of the 12-layer rigid-flex PCB was 2mm. The thickness of the laser-cut single-layer connecting ribs produced using the air layer fabrication method of the present invention was 0.167mm. During laser cutting, the laser energy was adjusted based on the thickness of each connecting rib when the laser cutting profile was cut. The laser cutting parameters ranged from a pulse frequency of 1000kHz, a laser energy of 8W, a cutting speed of 1200mm / s, and 20 cuts.

[0055] It should be noted that the thickness of a connecting rib is consistent with the thickness of an inner layer of soft board. Since only the connecting rib position is cut, severe carbonization of the edge due to excessive laser cutting energy is avoided, thereby completing the shape processing of the soft board at the air layer position.

[0056] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for manufacturing a rigid-flex board with an air layer, characterized in that: The steps include: S1. Pre-windowing the inner adhesive layer of the rigid-flex board to obtain an inner adhesive layer with adhesive layer windows, wherein the adhesive layer windows correspond to the area where the air layer of the soft board area of ​​the rigid-flex board is located; S2. A flexible board having an insulating layer and a circuit layer is provided as an inner-layer flexible board. A window is opened in a waste area of ​​the inner-layer flexible board corresponding to the air layer in the flexible board area, with connecting ribs retained at the window opening positions. An inner-layer flexible board having inner-layer flexible board windows and connecting ribs is prepared for standby use. The connecting ribs between two adjacent stacked inner-layer flexible boards are sequentially staggered and spaced apart by a first spacing. S3, sequentially stacking the inner soft boards of different layers obtained in step S2 through the inner rubber layer obtained in step S1 and pressing them together to obtain a multilayer board; S4. Carry out subsequent processing according to product design; S5. Laser cutting for shape processing: When laser cutting the shape, adjust the laser energy according to the thickness of an inner layer board. Laser cutting removes the connecting ribs in the waste area to obtain a single finished soft and hard combination circuit board.

2. The method for manufacturing a rigid-flex PCB according to claim 1, wherein: The soft board area of ​​the rigid-flex board has several layers of inner soft boards, and the several layers of inner soft boards are stacked in sequence from top to bottom.

3. The method for manufacturing a rigid-flex PCB according to claim 1, wherein: The area corresponding to the soft board area includes a waste area and a soft board reserved area. The connection between the waste area and the soft board reserved area is an outer cutting line. The inner soft board window is opposite to and overlaps with the waste area.

4. The method for manufacturing a rigid-flex PCB according to claim 3, wherein: The connecting ribs are connected to the inner soft boards in the soft board reserved area, and the connecting ribs of the inner soft boards of any stacked layers in the soft board area do not overlap.

5. The method for manufacturing a rigid-flex PCB according to claim 1, wherein: The connecting ribs of the inner layer soft boards of any stack in the soft board area are arranged in parallel, and the width of the connecting ribs is greater than or equal to 4.5 mm.

6. The method for manufacturing a rigid-flex PCB according to claim 1, wherein: The laser parameter ranges for the laser cutting for shape processing in step S5 are: pulse frequency of 960-1000kHz, laser energy of 8-8.5W, cutting speed of 1160-1200mm / s, and number of cutting times of 18-20 times.

7. The method for manufacturing a rigid-flex PCB according to claim 1, wherein: The value of the first spacing is 2 mm.

8. The method for manufacturing a rigid-flex PCB according to claim 1, wherein: The size of the adhesive layer window is larger than the size of the soft board reserved area.

9. The method for manufacturing a rigid-flex PCB according to claim 8, wherein: The edge line of the adhesive layer window is at a first distance from the outline line of the flexible board reserved area, and the value range of the first distance is 2.5-3.5 mm.

10. The method for manufacturing a rigid-flex PCB according to claim 1, wherein: In step S4, the specific processing steps of subsequent processing include mechanical drilling, copper electroplating, circuit, ink, and surface treatment.

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