Manufacturing method of rigid-flex board of thin-plate thick-copper strong-current-carrying circuit

Abstract

The invention discloses a manufacturing method of a thin plate body thick copper strong current-carrying circuit rigid-flex board, the rigid-flex board comprises a flexible area and a rigid area, a thick copper layer is half-etched twice to respectively form a first rigid core board and a second rigid core board, and the two half-etched patterns correspond to each other to form a complete circuit; taking a double-sided thick-copper flexible copper-clad plate to manufacture a flexible plate circuit pattern, pasting a first covering film on a corresponding flexible area, then carrying out silk-screen printing of resin ink on a corresponding rigid area, and drying to form a flexible core plate; taking a prepreg, a low-flow-glue prepreg and the core plate to be stacked and then laminated to form a laminated plate; manufacturing a surface circuit pattern, a solder mask and an uncovering layer on the laminated board in sequence to form a rigid-flexible combined board; according to the manufacturing method, the line gaps are filled, and the prepregs only play a bonding role, so that the thickness of the prepregs arranged between the layers can be effectively reduced, and the problems of infirm pressing, poor glue filling and the like caused by the fact that large glue needs to be filled in the line gaps of the thick copper circuit board are solved.

Description

Technical Field

[0001] The invention relates to the field of manufacturing rigid-flexible circuit boards, and in particular to a method for manufacturing a rigid-flexible circuit board with a thin plate body, thick copper and strong current-carrying circuit. Background Art

[0002] Thick copper high current-carrying rigid-flex PCB is widely used in power modules, vehicle systems and other fields because of its high current-carrying characteristics and ability to meet the needs of complex circuit design.

[0003] Thick copper circuit boards have thicker circuit copper thickness, and require more glue filling in the circuit pattern gaps. Therefore, thicker prepregs are needed as interlayer bonding layers during the lamination process to meet the glue filling requirements. However, this will increase the thickness of the thick copper circuit board and make it difficult to install in a small space.

[0004] In addition, the following problems may occur when using prepreg to fill glue:

[0005] (1) Using a prepreg with a high colloid content requires a greater pressing force. Excessive pressing force is prone to glue overflow. If the pressing force is reduced, it is easy to cause insufficient glue filling and interlayer voids.

[0006] (2) Using low-flow prepreg with a small amount of glue requires greater pressing force to meet the filling requirements, but it is easy to cause problems such as deformation of the board and circuit;

[0007] (3) When thicker prepreg is used, the thickness of the prepreg layer after lamination is added to the thickness of the circuit pattern, resulting in a board that is too thick, which is not conducive to application requirements in a narrow space.

[0008] Therefore, in order to solve the problems raised by the above background technology, it is necessary to provide a method for manufacturing a rigid-flexible board with a thin plate body, thick copper and strong current-carrying circuit. Summary of the invention

[0009] The present invention aims to solve the problem that the thick copper strong current-carrying rigid-flexible junction board in the prior art requires a thin board body, strong current-carrying and other comprehensive performances, and proposes a method for manufacturing a thin board body thick copper strong current-carrying circuit rigid-flexible junction board, the rigid-flexible junction board includes a flexible area and a rigid area, and the manufacturing method includes the following steps:

[0010] S10: Take the thick copper layer and make a blue glue layer on the first side thereof, make a circuit pattern on the second side, form a first half-etched pattern, and press the first glue-filled prepreg, and then tear off the blue glue layer to form a first rigid core board;

[0011] S20: making a circuit pattern on the first surface to form a second half-etched pattern, and then laminating a second glue-filled prepreg on the second surface, and polishing to form a second rigid core board; the first half-etched pattern corresponds to the second half-etched pattern;

[0012] S30: taking a double-sided thick copper flexible copper-clad board, making a flexible board circuit pattern on its surface, and applying a first covering film to the corresponding flexible area, and then screen-printing resin ink on the corresponding rigid area and drying it to form a flexible core board;

[0013] S40: Take a prepreg, a low-flow glue prepreg, the first rigid core board, the second rigid core board and the flexible core board, stack them to form a stacked structure, and then press them together to form a pressed board; a second covering film is attached to the flexible area on the surface of the low-flow glue prepreg opposite to the flexible core board; the stacked structure is: the flexible core board is arranged between two of the first rigid core boards, and a plurality of the second rigid core boards are stacked between the first rigid core board and the flexible core board; a prepreg is arranged between the first rigid core board and the second rigid core board and between two adjacent second rigid core boards, and a low-flow glue prepreg is arranged between the second rigid core board and the flexible core board; the first surface is located on the surface of the stacked structure;

[0014] S50: forming a surface circuit pattern and a solder resist layer on the surface of the laminated board in sequence, and then performing a cover-lifting process to form the rigid-flexible board; the surface circuit pattern corresponds to the first half-etched pattern.

[0015] Furthermore, the first half-etched pattern is 2 / 3 to 4 / 5 of the thickness of the thick copper layer.

[0016] Furthermore, the number of the second rigid core panels on both sides of the flexible core panel in the stacked structure is equal.

[0017] Furthermore, the polishing is polishing the second glue-filled prepreg until the copper layer on the second surface is exposed.

[0018] Furthermore, after attaching the second covering film, deep holes are drilled on the edge of the second covering film.

[0019] Furthermore, the uncovering process is: controlling the depth of the milling plate from the edge of the flexible area corresponding to the surface of the solder mask layer to the position of the controlled depth hole, and then peeling off the rigid board layer corresponding to the upper part of the flexible area.

[0020] Furthermore, the resin ink fills the circuit gaps of the flexible board circuit pattern and covers the flexible board circuit pattern.

[0021] Furthermore, the glue content of the prepreg is 55% to 65%, and the glue content of the low-flow prepreg is 45% to 52%.

[0022] Furthermore, the copper thickness of the thick copper layer and the double-sided thick copper flexible copper clad laminate is greater than or equal to 70 μm.

[0023] Furthermore, the second surface of the second rigid core board corresponds to the first rigid core board.

[0024] The technical solution of the present invention adopts a manufacturing method in which a thick copper layer is etched twice and then pressed together, and then the etched patterns are connected to form a complete circuit, so that the gaps of the thick copper circuit patterns of the formed rigid core board are "pre-filled" with colloid, thereby improving the flatness of the rigid core board and reducing the thickness of the board. In addition, the thickness of the prepreg used for the two etchings can be selectively reduced according to the thickness of the etched circuit, further reducing the thickness of the circuit board; by combining the two prepregs, the problem of the low-flow glue prepreg being unable to be pressed solidly when pressing the thick copper board due to the large glue filling area is solved, and the use of multiple low-flow glue prepregs is also avoided. The problem of glue overflow after the curing sheet is pressed; based on the above production, the line gap has been filled, and the semi-cured sheet is only used for bonding, and no longer for filling glue. Therefore, during pressing, the thickness of the semi-cured sheet set between layers can be effectively reduced, which solves the problems of loose pressing, poor filling, and voids between layers caused by the need to fill larger line gaps with glue on thick copper circuit boards. The overall production method forms a rigid-flexible board with a smaller thickness, effectively improving the applicability of rigid-flexible boards in narrow installation spaces, and realizing the technology of manufacturing and applying thick copper and high current-carrying circuit boards on thinner circuit boards. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0026] Figure 1 A schematic diagram of the process flow of a rigid-flexible circuit board according to an embodiment of the present invention;

[0027] Figure 2 It is a schematic structural diagram of manufacturing a first half-etched pattern for a thick copper layer according to an embodiment of the present invention;

[0028] Figure 3 It is a structural schematic diagram of a first rigid core plate according to an embodiment of the present invention;

[0029] Figure 4A schematic diagram of a structure for making a second half-etched pattern for a thick copper layer according to an embodiment of the present invention

[0030] Figure 5 It is a schematic structural diagram of a second rigid core plate according to an embodiment of the present invention;

[0031] Figure 6 It is a schematic structural diagram of a flexible core board according to an embodiment of the present invention;

[0032] Figure 7 A schematic diagram of a stacked structure according to an embodiment of the present invention;

[0033] Figure 8 It is a schematic structural diagram of a pressed plate according to an embodiment of the present invention;

[0034] Fig. 9 Schematic diagram of the structure of a rigid-flex board according to an embodiment of the present invention.

[0035] Description of Figure Numbers:

[0036]

[0037]

[0038] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, inside, outside...) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0041] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0042] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0043] See also Figure 1 , Figure 1 Schematic diagram of the process flow of an embodiment of the present invention.

[0044] The manufacturing process of the embodiment of the present invention includes using Figure 1 The following will implement the various steps in the process Figure 1 Each step in the process is further explained step by step.

[0045] See also Figure 2 and Figure 3 , Figure 2 It is a schematic structural diagram of manufacturing a first half-etched pattern for a thick copper layer according to an embodiment of the present invention; Figure 3 It is a schematic structural diagram of the first rigid core plate according to an embodiment of the present invention.

[0046] Step S10:

[0047] Take the thick copper layer 1010 and make a blue glue layer 1020 on the first side, make a circuit pattern on the second side, form a first half-etched pattern 1030, and press the first glue-filled semi-cured sheet 1040, then tear off the blue glue layer 1020 to form a first rigid core board 10.

[0048] In the present embodiment, a blue glue layer 1020 is first produced on the first surface of the thick copper layer 1010, and the blue glue layer 1020 is used as a supporting layer to provide support for the subsequent production of the first half-etched pattern 1030 of the thick copper layer 1010. Moreover, since the blue glue layer 1020 is strippable, it can be peeled off after processing is completed without affecting the original copper surface effect.

[0049] It is worth noting that the circuit pattern is divided into two half-etchings and then connected to form a complete circuit in this embodiment because half of the copper is etched first, and the first half-etched pattern 1030 is 2 / 3 to 4 / 5 of the thickness of the thick copper layer, which can provide a certain filling depth for the first glue-filled semi-cured sheet 1040 to be pressed in the subsequent process. The unetched copper layer is used to ensure the integrity of the copper layer, which is also beneficial for the first glue-filled semi-cured sheet 1040 to be better filled and combined with the first half-etched pattern 1030, preventing one-time complete etching, resulting in scattered circuits and too deep circuit gaps, resulting in insufficient filling of the subsequent direct pressing of the semi-cured sheet or the circuit being pressed and offset when the filled semi-cured sheet is pressed.

[0050] See also Figure 4 and Figure 5; Figure 4 It is a schematic structural diagram of manufacturing a second half-etched pattern for a thick copper layer according to an embodiment of the present invention; Figure 5 It is a schematic structural diagram of a second rigid core plate according to an embodiment of the present invention.

[0051] Step S20:

[0052] A circuit pattern is made on the first surface to form a second half-etched pattern 2010 , and then a second glue-filled prepreg 2020 is pressed on the second surface and polished to form a second rigid core board 20 .

[0053] The first half-etched pattern 1030 of this embodiment corresponds to the second half-etched pattern 2010, and is connected to form a complete circuit, so that the formed full-etched pattern is completely filled with the first glue-filled semi-cured sheet 1040 and the second glue-filled semi-cured sheet 2020, forming a state in which the circuit pattern is "embedded in the semi-cured sheet layer", so that the first glue-filled semi-cured sheet 1040 and the second glue-filled semi-cured sheet 2020 "pre-fill" the circuit gap, which is conducive to setting the semi-cured sheets between layers thinner during subsequent lamination, thereby reducing the thickness of the entire circuit board.

[0054] It is worth noting that the thickness of the glue-filled semi-pregs used for the two fillings is different. Since the first half-etched pattern 1030 is 2 / 3 to 4 / 5 of the thickness of the thick copper layer 1010, and the remaining copper thickness of the second half-etched pattern 2010 is 1 / 5 to 1 / 3, the deeper the etching of the circuit pattern, the greater the demand for the glue-filled semi-preg. Therefore, the thickness of the first glue-filled semi-preg 1040 used for the first half-etched pattern 1030 is greater than that of the second glue-filled semi-preg 2020 used for the second half-etched pattern 2010.

[0055] In addition, the depth of the first half-etched pattern 1030 is greater than the depth of the second half-etched pattern 2010 because the second side needs to be polished in subsequent processing. The polishing is to polish the second glue-filled semi-cured sheet 2020 until the copper layer on the second side is exposed, which provides a core board foundation for subsequent pressing processing. Therefore, the etching depth of the second half-etched pattern 2010 is shallow, and the thickness of the second glue-filled semi-cured sheet 2020 required to be pressed is also relatively thin. At the same time, it also makes subsequent polishing more convenient and improves the polishing processing efficiency.

[0056] See also Figure 6 , Figure 6 It is a schematic structural diagram of a flexible core board according to an embodiment of the present invention.

[0057] Step S30:

[0058] Take a double-sided thick copper flexible copper-clad board, make a flexible board circuit pattern 3010 on its surface, and apply a first covering film 3020 to the corresponding flexible area 3040, and then screen-print resin ink 3030 on the corresponding rigid area 3050 and dry it to form a flexible core board 30.

[0059] In this embodiment, resin ink 3030 is used to fill the line gaps of the flexible board circuit pattern 3010 and cover the flexible board circuit pattern 3010 to make the surface of the flexible core board 30 smooth. In addition, since the material properties of the resin ink 3030 are similar to the material properties of the low-flow adhesive semi-cured sheet 4020 used for subsequent pressing, the resin ink 3030 is used to form a solidified layer. In the subsequent pressing process, the mutual bonding with the low-flow adhesive semi-cured sheet 4020 can effectively form an interlayer bonding effect.

[0060] It is worth noting that the copper thickness of the thick copper layer 1010 and the double-sided thick copper flexible copper clad laminate is greater than or equal to 70 μm.

[0061] See also Figure 7 and Figure 8 , Figure 7 A schematic diagram of a stacked structure according to an embodiment of the present invention; Figure 8 It is a schematic structural diagram of a pressed plate according to an embodiment of the present invention.

[0062] Step S40:

[0063] The prepreg 4010 , the low-flow adhesive prepreg 4020 , the first rigid core board 10 , the second rigid core board 20 and the flexible core board 30 are stacked to form a stacked structure 40 , and then pressed together to form a pressed board 50 .

[0064] A second covering film 4030 is affixed to the surface of the low-flow semi-cured sheet 4020 in the flexible area 3040 opposite to the flexible core board 30. This is because the rigid board layer corresponding to the upper part of the flexible area 3040 needs to be uncovered later. The second covering film 4030 and the first covering film 3020 are arranged to form a film-to-film structure. The inertness of the covering film (generally a polyimide material) is stronger than that of the semi-cured sheet (generally an epoxy resin material). During pressing, the film-to-film structure cannot form a mutual adhesion effect, which is convenient for subsequent release and uncovering. After the second covering film 4030 is affixed, deep holes are drilled on the surface of the low-flow semi-cured sheet 4020 at the edge of the second covering film 4030 to form an effective coordination with the subsequent uncovering process and improve the efficiency of the uncovering process.

[0065] The stacked structure 40 is as follows: the flexible core board 30 is disposed between two first rigid core boards 10 , and a plurality of second rigid core boards 20 are stacked between the first rigid core board 10 and the flexible core board 30 .

[0066] In this embodiment, the number of second rigid core boards 20 on both sides of the flexible core board 30 in the stacked structure 40 is equal. Therefore, when pressing, since the stacked structure 40 as a whole is a symmetrical structure with the flexible core board 30 as the center, the auxiliary mechanisms on both sides are the same during pressing, and the two sides of the entire stacked structure 40 are evenly stressed, and the pressing effect is better.

[0067] In the present embodiment, the semi-cured sheets that play a bonding role in the stacked structure 40 include two types of semi-cured sheets with different glue contents, namely, a semi-cured sheet is arranged between the first rigid core board 10 and the second rigid core board 20 and between two adjacent second rigid core boards 20, which is a semi-cured sheet 4010 with ordinary glue flow, which has a relatively high glue content and good adhesion and filling performance; a low glue flow semi-cured sheet 4020 is arranged between the second rigid core board 20 and the flexible core board 30; at this time, the colloid content is relatively small, which prevents excessive glue flow from causing excessive glue overflow at the rigid-flexible combination position, resulting in difficulty in subsequent uncovering, and can also avoid the problem of unevenness caused by excessive glue filling or excessive expansion and contraction of the board due to pressing between the second rigid core board 20 and the flexible core board 30.

[0068] It is worth noting that the glue content of the prepreg 4010 is 55% to 65%, and the glue content of the low-flow prepreg 4020 is 45% to 52%.

[0069] The first surface is located on the surface of the stacked structure 40; that is, the second surface exposed after polishing is a complete copper layer, which needs to be used as the outer surface of the stacked structure 40 to ensure that the force on the two surface copper layers of the entire stacked structure 40 is uniform and the interlayer bonding is tighter.

[0070] In this embodiment, the second copper layer of the second rigid core board 20 corresponds to the first rigid core board 10 , which can form a more uniform circuit layer distribution effect as a whole and improve the bonding force between layers.

[0071] See also Fig. 9 , Fig. 9 Schematic diagram of the structure of a rigid-flex board according to an embodiment of the present invention.

[0072] Step S50:

[0073] A surface circuit pattern 6010 and a solder mask layer 6020 are sequentially produced on the surface of the laminated board 50, and then the cover is removed to form a rigid-flexible board 60; the surface circuit pattern 6010 corresponds to the first half-etched pattern 1030, that is, the surface circuit pattern 6010 produced last corresponds to the first half-etched pattern 1030 and is connected to form a complete circuit pattern.

[0074] The uncovering process in this embodiment is as follows: depth milling is performed from the edge of the flexible area 3040 corresponding to the surface of the solder mask layer to the controlled depth hole position, and then the uncovering area 6030 formed by the rigid board layer corresponding to the upper part of the flexible area 3040 is peeled off to form a rigid-flexible composite board as a whole.

[0075] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for manufacturing a thin plate body thick copper strong current-carrying circuit rigid-flexible board, the rigid-flexible board comprising a flexible area and a rigid area, characterized in that: The production method comprises the following steps: S10: Take the thick copper layer and make a blue glue layer on the first side thereof, make a circuit pattern on the second side, form a first half-etched pattern, and press the first glue-filled prepreg, and then tear off the blue glue layer to form a first rigid core board; S20: making a circuit pattern on the first surface to form a second half-etched pattern, and then laminating a second glue-filled prepreg on the second surface, and polishing to form a second rigid core board; The first half-etched pattern corresponds to the second half-etched pattern; S30: taking a double-sided thick copper flexible copper-clad board, making a flexible board circuit pattern on its surface, and applying a first covering film to the corresponding flexible area, and then screen-printing resin ink on the corresponding rigid area and drying it to form a flexible core board; S40: stacking the prepreg, the low-flow prepreg, the first rigid core board, the second rigid core board and the flexible core board to form a stacked structure, and then pressing them together to form a pressed board; A second covering film is attached to the flexible area of ​​the surface of the low-flow prepreg sheet opposite to the flexible core board; The stacked structure is as follows: the flexible core board is arranged between two of the first rigid core boards, and a plurality of the second rigid core boards are stacked between the first rigid core board and the flexible core board; A prepreg is arranged between the first rigid core board and the second rigid core board and between two adjacent second rigid core boards, and a low-flow prepreg is arranged between the second rigid core board and the flexible core board; The first surface is located on the surface of the stacked structure; S50: forming a surface circuit pattern and a solder mask layer on the surface of the laminated board in sequence, and then performing a cover-lifting process to form the rigid-flexible board; The surface circuit pattern corresponds to the first half-etched pattern.

2. The method for manufacturing a thin plate body thick copper strong current-carrying circuit rigid-flexible bonding board as claimed in claim 1, characterized in that: The first half-etched pattern is 2 / 3 to 4 / 5 of the thickness of the thick copper layer.

3. The method for manufacturing a thin plate body thick copper strong current carrying circuit rigid-flexible board as claimed in claim 1, characterized in that: The number of the second rigid core panels on both sides of the flexible core panel in the stacked structure is equal.

4. The method for manufacturing a thin plate body thick copper strong current carrying circuit rigid-flexible bonding board as claimed in claim 1, characterized in that: The polishing is to polish the second glue-filled prepreg until the copper layer on the second surface is exposed.

5. The method for manufacturing a thin plate body thick copper strong current carrying circuit rigid-flexible board as claimed in claim 1, characterized in that: After attaching the second covering film, deep holes are drilled on the edge of the second covering film.

6. The method for manufacturing a thin plate body thick copper strong current carrying circuit rigid-flexible bonding board as claimed in claim 5, characterized in that: The uncovering process is: controlling the depth of the milling plate from the edge of the flexible area corresponding to the surface of the solder mask layer to the position of the controlled depth hole, and then peeling off the rigid board layer corresponding to the upper part of the flexible area.

7. The method for manufacturing a thin plate body thick copper strong current carrying circuit rigid-flexible board as claimed in claim 1, characterized in that: The resin ink fills the circuit gaps of the flexible board circuit pattern and covers the flexible board circuit pattern.

8. The method for manufacturing a thin plate body thick copper strong current carrying circuit rigid-flexible board as claimed in claim 1, characterized in that: The glue content of the prepreg is 55% to 65%, and the glue content of the low-flow prepreg is 45% to 52%.

9. The method for manufacturing a thin plate body thick copper strong current carrying circuit rigid-flexible board as claimed in claim 1, characterized in that: The copper thickness of the thick copper layer and the double-sided thick copper flexible copper clad laminate is greater than or equal to 70 μm.

10. The method for manufacturing a thin plate body thick copper strong current carrying circuit rigid-flexible board as claimed in claim 1, characterized in that: The second face of the second rigid core panel corresponds to the first rigid core panel.

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