WO2015014048A1 - 一种刚挠结合印制电路板及其制作方法 - Google Patents

一种刚挠结合印制电路板及其制作方法 Download PDF

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Publication number
WO2015014048A1
WO2015014048A1 PCT/CN2013/087886 CN2013087886W WO2015014048A1 WO 2015014048 A1 WO2015014048 A1 WO 2015014048A1 CN 2013087886 W CN2013087886 W CN 2013087886W WO 2015014048 A1 WO2015014048 A1 WO 2015014048A1
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Prior art keywords
board
circuit board
flexible
rigid
sub
Prior art date
Application number
PCT/CN2013/087886
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English (en)
French (fr)
Inventor
黄勇
吴会兰
陈正清
苏新虹
Original Assignee
北大方正集团有限公司
珠海方正科技高密电子有限公司
珠海方正印刷电路板发展有限公司
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Application filed by 北大方正集团有限公司, 珠海方正科技高密电子有限公司, 珠海方正印刷电路板发展有限公司 filed Critical 北大方正集团有限公司
Publication of WO2015014048A1 publication Critical patent/WO2015014048A1/zh

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Classifications

    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05KPRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00Apparatus or processes for manufacturing printed circuits
    • H05K3/46Manufacturing multilayer circuits
    • H05K3/4688Composite multilayer circuits, i.e. comprising insulating layers having different properties
    • H05K3/4691Rigid-flexible multilayer circuits comprising rigid and flexible layers, e.g. having in the bending regions only flexible layers

Definitions

  • the present invention relates to the field of printed circuit boards, and in particular, to a rigid-flex printed circuit board and a manufacturing method thereof. Background technique
  • PCB Printed Circuit Board
  • printed circuit boards can be classified into rigid printed circuit boards, flexible printed circuit boards (FPC), and rigid-flex printed circuit boards.
  • FPC flexible printed circuit boards
  • a rigid-flex printed circuit board is a printed circuit board that includes one or more rigid regions on one printed circuit board and one or more flexible regions as a rigid board and a flexible board. The combination of both rigid and flexible boards.
  • the flexible circuit board has the characteristics of being freely bendable, wound, and folded
  • the product made of the rigid-flex printed circuit board is easy to assemble and can be folded up to form a better tight package form, thereby
  • the wiring and cable connection are eliminated, the soldering of the connector and the end point is reduced, the space occupied by the product and the weight of the product are reduced, the electrical interference is reduced, the electrical performance is improved, and the electronic device is made to be light and thin.
  • the manufacturing process of the rigid-flex printed circuit board is as follows: First, the flexible circuit board A1 and the rigid circuit board A2 are placed side by side in the horizontal direction; and then the flexible circuit board A1 and the rigid circuit board A2 are upper and lower.
  • the prepreg A3 is disposed on the surface, wherein a portion of the flexible circuit board A1 is exposed (ie, a portion of the flexible circuit board A1 that needs to be bent or folded); after the pressing treatment, the prepreg A3 is converted from a semi-cured state to a complete a state of being cured, thereby connecting the flexible circuit board A1 and the rigid circuit board A2 to form a rigid-flex printed circuit board, the structure of which is shown in FIG. 1, and the flexible circuit board A1 is shown in FIG.
  • the via is in communication with the line of the outer layer of the rigid circuit board A2.
  • the substrate of the flexible circuit board is composed of polyimide or liquid crystal polymer, it has excellent bending properties, but its rigidity is insufficient and deformation is easy, and the thickness of the flexible circuit board is generally higher than that of the rigid circuit board. The thickness is much smaller. Therefore, when the press-bonding process is performed, the flexible circuit board is easily deformed, and the rigid circuit board is misaligned, resulting in poor connection between the conductive layer of the flexible circuit board and the conductive layer of the rigid circuit board. , even disconnected directly.
  • the embodiment of the invention provides a rigid-flex printed circuit board and a manufacturing method thereof, which are used for solving the process of preparing a rigid-flex printed circuit board, which easily leads to a conductive layer and a rigid circuit board of the flexible circuit board.
  • the conductive layer is poorly connected and even directly disconnected.
  • Embodiments of the present invention provide a method for fabricating a rigid-flex printed circuit board, including:
  • the absolute value of the difference between the thickness of the flexible daughterboard and the thickness of the rigid daughterboard is not more than 50 micrometers.
  • the absolute value of the difference between the size of the window and the size of the flexible daughterboard is in the range of not less than 10 meters and not more than 100 meters.
  • the laminating further comprises: placing metal on the upper surface and/or the lower surface of the rigid sub-board and the flexible sub-board Foil.
  • the metallizing the through hole further includes:
  • the surface of the rigid-flex printed circuit board obtained by pressing is metallized to form a conductive layer of the rigid-flex printed circuit board.
  • the through hole obtained by the drilling process also penetrates the cover film of the flexible circuit board.
  • the through hole is metallized, and specifically includes:
  • the through hole is subjected to a plating treatment, and the conductive paste is filled in the through hole after plating.
  • the forming the flexible daughterboard specifically includes: Pressing a peelable protective film on a surface of a portion of the flexible circuit board where the exposed portion is required; and pre-compressing the second portion of the B-stage state on a lower surface of the flexible circuit board press-bonded with the peelable protective film An insulating substrate, wherein a temperature of the pre-compression treatment is higher than a normal temperature and lower than a glass transition temperature of a resin in the second insulating substrate.
  • forming the flexible daughterboard specifically includes:
  • the temperature of the pre-compression treatment is higher than a normal temperature and lower than a glass transition temperature of the resin in the second insulating substrate ; as well as
  • a buffer material having a coating effect is filled in the window of the second insulating substrate.
  • Embodiments of the present invention provide a rigid-flex printed circuit board, wherein the rigid-flex printed circuit board is fabricated according to the above method.
  • the second insulating substrate in the B-stage state is pre-compressed on the surface of the flexible circuit board to form a flexible daughter board; the window is processed by the rigid daughter board to obtain the same shape and size as the flexible daughter board. a window larger than the flexible sub-board; stacking the rigid sub-board and the flexible sub-board to embed the flexible sub-board into the window; and pressing the rigid sub-board and the flexible sub-board after the lamination to obtain a rigid-flex combination a printed circuit board; drilling a hole in a region other than the exposed portion of the flexible circuit board to obtain a through hole penetrating the second insulating substrate; metallizing the through hole and forming an outer layer a wiring pattern of the conductive layer; removing other structures on the portion of the flexible circuit board that need to be exposed.
  • the flexible daughter board includes not only the flexible circuit board, but also the second insulating substrate covering the upper surface and the lower surface of the flexible circuit board, the flexible daughter board has a certain rigidity and is not easily deformed during the manufacturing process. Therefore, the alignment accuracy of the flexible daughter board and the rigid daughter board during the manufacturing process is improved, and the electrical connection reliability of the conductive layer of the flexible circuit board and the conductive layer of the rigid circuit board is also improved.
  • FIG. 1 is a schematic structural view of a rigid-flex printed circuit board in the background art
  • FIG. 2 is a flow chart of a method for fabricating a rigid-flex printed circuit board according to the present invention
  • FIG. 3A is a schematic view of a hole obtained after a pair of drilling processes in a smashing manner according to the present invention
  • FIG. 3B is a schematic view showing a hole obtained by drilling after the drilling method according to the second embodiment of the present invention
  • 4 is a flow chart of a first method for manufacturing a flexible daughterboard according to the present invention
  • FIG. 5 is a flowchart of a method according to Embodiment 1 of the present invention.
  • 6A to 6G are schematic cross-sectional views showing a process of fabricating a flexible daughterboard by the method of the first embodiment provided by the present invention.
  • FIG. 7 is a flow chart of a second method for manufacturing a flexible daughter board according to the present invention.
  • FIG. 8 is a flowchart of a method according to Embodiment 2 of the present invention.
  • 9A to 9E are schematic cross-sectional views showing a process of fabricating a flexible daughterboard by the method of the second embodiment provided by the present invention;
  • FIG. 11A to FIG. 11M are schematic cross-sectional views showing a process of fabricating a rigid-flex printed circuit board by the method of the third embodiment provided by the present invention.
  • FIG. 12 is a cross-sectional structural view showing each structure of the stacking process in the fourth embodiment of the present invention. detailed description
  • a method for fabricating a rigid-flex printed circuit board includes the following steps: Step 21: pre-compressing a second insulating substrate in a B-stage state on a surface of a flexible circuit board, The flexible daughter board is formed so that the flexible circuit board has a certain rigidity and is not easily deformed in the subsequent manufacturing process.
  • the absolute value of the difference between the thickness of the flexible daughterboard formed in this step and the thickness of the rigid daughterboard is not more than 50 micrometers, thereby avoiding the flexible circuit board during subsequent stacking and pressing.
  • the conductive layer is poorly connected to the conductive layer of the rigid circuit board, and is even directly disconnected.
  • Step 22 Opening the window of the rigid daughterboard to obtain a window having the same outer shape as the flexible daughterboard and having a larger size than the flexible daughterboard.
  • the absolute value of the difference between the size of the window formed by opening the window of the rigid daughter plate and the size of the flexible daughter board formed in step 21 in the step is: not less than 10 micrometers ( ⁇ ) and not greater than 100 micron ( ⁇ ), so that when the subsequent stack is stacked, it is convenient to embed the flexible daughter board into the window.
  • Step 23 Stack the rigid daughterboard and the flexible daughterboard so that the flexible daughterboard is embedded in the window of the rigid daughterboard.
  • Step 24 Pressing the rigid daughter board and the flexible daughter board after the stacking to obtain a rigid-flex printed circuit board.
  • the second insulating substrate in the flexible daughter board is in a collapsed state (ie, a semi-cured state)
  • the temperature at the time of pressing reaches the glass transition temperature of the resin in the second insulating substrate ( TG)
  • the flexible daughterboard and the rigid daughterboard can be joined together by the resin in the second insulating substrate during the pressing process, and after the pressing, due to the curing of the resin in the second insulating substrate , the flexible daughter board and the rigid daughter board are bonded together to form a whole.
  • Step 25 drilling a hole in the flexible circuit board except for the exposed portion, and obtaining a through hole penetrating the second insulating substrate, wherein the through hole is used for connecting the conductive circuit of the flexible circuit board a layer and a rigid layer bonded to the conductive layer of the printed circuit board;
  • the through hole obtained in this step may be a through hole or a blind hole.
  • the surface of the flexible circuit board of the flexible daughter board further includes a cover film for protecting the flexible circuit board, in this step, the through hole obtained by drilling the hole also penetrates the cover film of the flexible circuit board. .
  • Step 26 metallizing the through hole obtained after drilling, and fabricating the circuit pattern of the outer conductive layer of the rigid-flex printed circuit board.
  • Step 27 Remove the other structure on the exposed portion of the flexible circuit board so that a portion of the flexible circuit board can be exposed, and the exposed portion of the flexible circuit board can be bent.
  • laser-controlled deep-cutting or mechanical-controlled deep-milling can be used to remove other structures on the flexible circuit board that need to be exposed.
  • the flexible daughter board since the flexible daughter board includes not only the flexible circuit board but also the second insulating substrate covering the surface of the flexible circuit board, the flexible daughter board has a certain rigidity during the manufacturing process. It is not easy to be deformed, thereby improving the alignment accuracy of the flexible daughter board and the rigid daughter board during the manufacturing process, and also improving the electrical connection reliability of the conductive layer of the flexible circuit board and the conductive layer of the rigid circuit board.
  • step 21 The technical terms involved in step 21 are explained below.
  • a flexible circuit board generally includes a flexible insulating layer and a flexible conductive layer covering the upper surface and/or the lower surface of the flexible insulating layer.
  • the flexible circuit board may be a single panel or a double panel; preferably,
  • the surface of the flexible circuit board is further provided with a cover film; wherein the flexible conductive layer is preferably calendered Made of copper foil or electrolytic copper foil, the flexible insulating layer can be made of polyimide or liquid crystal polymer, and the cover film can be made of polyester (PET), polyimide (PI), and / It is preferably made of a material such as polyfluorinated (PTFE).
  • the cover film is made of a polyimide-based material.
  • the second insulating substrate may be an insulating material formed by impregnating a resin (such as an epoxy resin, a phenol resin or a BT resin) with an electronic grade glass cloth or paper; or the second insulating substrate The resin may be in a B-Stage state, that is, a semi-cured state.
  • a resin such as an epoxy resin, a phenol resin or a BT resin
  • the resin may be in a B-Stage state, that is, a semi-cured state.
  • the through hole formed in the step 26 is metallized, and the following three methods are included: Method 1: The through hole is subjected to a hole filling plating process, so that the space in the hole is completely made of the plated metal m. Fill, see Figure 3A;
  • the crucible is filled with electroplated copper.
  • the through hole is plated, and the conductive paste is filled in the through hole after plating; specifically: the surface of the through hole is first plated, and then the through hole in the plating process is filled with conductive Conductive paste n, so that the space inside the hole is completely filled by the conductive paste n, as shown in FIG. 3B;
  • the electroplating treatment includes copper plating, direct plating, vacuum plating, and the like.
  • the conductive paste may be one of a copper paste, a silver paste or a carbon paste or a mixture of at least two.
  • the conductive paste may be one of a copper paste, a silver paste or a carbon paste or a mixture of at least two.
  • the rigid sub-board may use the first insulating substrate or the cladding metal plate.
  • the first insulating substrate may be an insulating material formed by impregnating a resin (such as an epoxy resin, a phenol resin or a BT resin) with an electronic grade glass cloth or paper; or the like in the first insulating substrate.
  • the resin may be in a B-stage state, that is, a semi-cured state; or may be in a C-stage state, that is, a fully cured state.
  • the metal-clad board comprises an insulating layer and a conductive layer covering at least one surface (ie, an upper surface and/or a lower surface) of the insulating layer; and the manufacturing process of the metal-clad board comprises the following steps:
  • the insulating substrate is subjected to a cutting treatment; the upper surface and/or the surface of the insulating substrate (the resin in the insulating substrate is in the B-stage state) is covered with a metal foil; and the insulating substrate and the metal foil are pressed together.
  • the metal-clad sheet may be a single-sided or double-sided metal-clad fiberglass reinforced epoxy resin sheet, a single-sided or double-sided metal-coated polytetrafluoroethylene sheet, Single-sided or double-sided metal-coated polyimide board, single-sided or double-sided metal-coated polyamide board, single-sided or double-sided metal cyanate resin board or double-sided metal-ceramic board.
  • the stacking of the rigid daughter board and the flexible daughter board in step 23 is specifically as follows:
  • a metal foil is placed on the rigid daughterboard and the upper and/or lower surface of the flexible daughterboard.
  • the through hole may be metallized by any of the above three methods.
  • the rigid daughter board and the metal foil placed on the upper surface and/or the lower surface of the flexible daughter board are also plated with a metal.
  • the rigid daughter board in the embodiment of the present invention uses the first insulating substrate, the rigid daughter board and the flexible daughter board are stacked in step 23, that is, the flexible daughter board is embedded in the rigidity. Inside the window of the daughter board.
  • the metallizing the through holes in step 26 further includes:
  • the surface of the rigid-flex printed circuit board obtained by pressing is metallized to form a conductive layer of the rigid-flex printed circuit board.
  • the through hole may be metallized by using the first mode or the second mode.
  • the surface of the rigid daughter board and the flexible daughter board is plated with a metal layer.
  • the conductive layer that just flexes the printed circuit board is composed of a metal layer formed by electroplating.
  • step 23 When the slab and the flexible daughterboard are stacked, it is no longer necessary to place a metal foil on the rigid sub-board and the upper or lower surface of the flexible sub-board.
  • the through hole may be metallized by any of the above three methods.
  • the through hole is metallized by the first method and the second method in the step 26, the surface of the rigid daughter board and the flexible daughter board is plated with a metal layer, and the rigid joint printing is performed.
  • the conductive layer of the circuit board is composed of a conductive layer of a metal-clad board and a metal layer formed by electroplating; if the through-hole is metallized by the third method in the step 26, the conductive layer of the rigid-flex printed circuit board is only The conductive layer of the metal-clad board is formed.
  • the flexible daughter board can be fabricated by any of the following methods:
  • Method 1 as shown in FIG. 4, the method includes the following steps:
  • Step 41 Pressing a peelable protective film on a surface of a portion of the flexible circuit board where the exposed portion is required;
  • Step 42 pre-compressing a second insulating substrate in a B-stage state (ie, a semi-cured state) on a surface of the flexible circuit board with the peelable protective film, thereby completing the fabrication of the flexible daughterboard.
  • the treated temperature is higher than normal temperature and lower than the glass transition temperature of the resin in the second insulating substrate.
  • normal temperature is also called general temperature or room temperature, and generally refers to 15 ° C ⁇ 25 ° C.
  • the peelable protective film pressed on the flexible circuit board has a thickness of 5 ⁇ m to 50 ⁇ m, and can be used in polyester (PET), polyimide (PI), and / or made of materials such as polyfluorinated (PTFE).
  • PET polyester
  • PI polyimide
  • PTFE polyfluorinated
  • the absolute value of the difference between the sum of the thicknesses of the pre-compressed second insulating substrate and the flexible circuit board and the thickness of the rigid daughter plate is not more than 5 (H m.
  • the temperature of the pre-compression treatment is preferably higher than normal temperature, but lower than the glass transition temperature of the resin in the second insulating substrate, so that the resin in the second insulating substrate is processed during the pre-compression treatment. Warming and softening to better fit on the surface of the flexible circuit board, and since the temperature of the pre-compression treatment is lower than the glass transition temperature of the resin, the resin is still in the B-stage, that is, curing does not occur, so as to facilitate the second The next press-bonding of the insulating substrate is cured.
  • the temperature of the pre-compression treatment ranges from 60 ° C to 150 ° C.
  • the glass transition temperature (TG) is an important characteristic parameter of the material, and many properties of the material change sharply around the glass transition temperature. As the temperature increases, the resin in the second insulating substrate first softens, and when the temperature rises to the glass transition temperature, a curing reaction occurs and the process is irreversible, i.e., the shape is not changed by heating again after cooling. According to the glass transition temperature, the resin can be divided into ordinary TG resin and high TG resin, ordinary TG > 130 degrees, high TG > 170 degrees. Therefore, in step 42, the temperature of the pre-compression treatment is preferably higher than 60 ° C, and for the resin of the ordinary material, the temperature of the pre-compression treatment should be lower than 125 °C.
  • Embodiment 1 As shown in FIG. 5, this embodiment includes the following steps:
  • Step 51 the material processing, cutting the original flexible copper clad plate into a board capable of being produced on the production line, See Figure 6A;
  • Step 52 a pattern transfer process, that is, a pattern of conductive lines forming the flexible circuit board, as shown in FIG. 6B;
  • Step 53 pressing the cover film a on the surface of the flexible circuit board to protect the flexible circuit board, see Figure 6C;
  • Step 54 cutting the peelable protective film b, the size of the peelable protective film b after cutting is the same as the size of the portion of the flexible circuit board that needs to be exposed, and the peelable protective film after cutting b is pressed onto the exposed portion of the flexible circuit board, as shown in Figure 6D;
  • the cutting method includes laser cutting, die cutting or mechanical milling.
  • Step 55 pre-compressing the second insulating substrate c on the surface of the flexible circuit board, so that the absolute value of the difference between the thickness of the second insulating substrate c and the flexible circuit board and the thickness of the rigid daughter board is not more than 50 micrometers, as shown in Fig. 6E, thereby completing the fabrication of the flexible daughterboard.
  • a panel containing a plurality of flexible sub-boards can be fabricated at one time, and after being completed, cut into a plurality of pieces as needed.
  • Flexible daughter board For example, assume that at the time of production, a panel containing two flexible daughter boards is fabricated, the structure of which is shown in Fig. 6F; and then the panel is cut to obtain two flexible daughter boards, as shown in Fig. 6G.
  • Method 2 Referring to FIG. 7, the method includes the following steps:
  • Step 71 window opening is performed at a position corresponding to a portion of the second insulating substrate that needs to be exposed by the flexible circuit board, and the obtained window has the same outer shape as that of the portion of the flexible circuit board that needs to be exposed.
  • the size of the window is the same as the size of the portion of the flexible circuit board that needs to be exposed;
  • the window can be opened by laser cutting, die cutting or mechanical milling.
  • Step 72 pre-compressing the second insulating substrate after the window is opened on the surface (ie, the upper surface and the lower surface) of the flexible circuit board, the pre-compression treatment temperature is higher than the normal temperature and lower than the second insulating substrate The glass transition temperature of the resin;
  • the absolute value of the difference between the thickness of the pre-compressed second insulating substrate and the flexible circuit board and the thickness of the rigid daughterboard is not more than 50 micrometers;
  • the temperature of the pre-compression treatment is preferably higher than the normal temperature, but lower than the glass transition temperature of the resin in the second insulating substrate, so that the resin in the second insulating substrate is softened by heating during the pre-compression treatment. Goodly conforming to the surface of the flexible circuit board, and since the temperature of the pre-compression treatment is lower than the glass transition temperature of the resin, the resin is still in the B-stage, that is, curing does not occur, so as to facilitate the second insulating substrate.
  • the next press-cure curing preferably, the temperature of the pre-compression treatment ranges from 60 ° C to 150 ° C.
  • Step 73 filling a window of the second insulating substrate with a buffering material having a covering effect, thereby completing the fabrication of the flexible daughter board.
  • the so-called overmolding means that the material can be closely adhered to the material adjacent thereto at a high temperature, and the surface of the material adjacent to the material is smooth or uneven, and can be closely adhered.
  • the window of the second insulating substrate is completely filled with the buffer material.
  • the buffer material filled in step 73 may be a material having a coating effect such as a silica gel sheet or a low-density polyethylene.
  • Embodiment 2 Referring to FIG. 8, the embodiment includes the following steps:
  • Step 81 the material processing, cutting the original flexible copper clad plate into a board capable of being produced on the production line, as shown in FIG. 6A;
  • Step 82 a pattern transfer process, that is, a pattern of conductive lines forming the flexible circuit board, as shown in FIG. 6B;
  • Step 83 pressing the cover film a on the upper and lower surfaces of the flexible circuit board to protect the flexible circuit Board, see Figure 6C;
  • Step 84 opening a window at a position corresponding to a portion of the second insulating substrate c that is exposed to the flexible circuit board, and obtaining an outer shape and a size of the window and a portion of the flexible circuit board that needs to be exposed
  • the shape and size are the same, as shown in Figure 9A;
  • Step 85 pre-pressing the fenestrated second insulating substrate c on the surface of the flexible circuit board, so that the difference between the thickness of the second insulating substrate c and the flexible circuit board and the thickness of the rigid daughterboard
  • the absolute value is not more than 5 (M meters, see Figure 9B;
  • Step 86 filling the window of the second insulating substrate c with a cushioning material d having a covering effect, thereby completing the fabrication of the flexible daughter board, as shown in FIG. 9C.
  • a panel containing a plurality of flexible sub-boards can be fabricated at one time, and after being completed, cut into a plurality of pieces as needed.
  • Flexible daughter board For example, assume that at the time of production, a panel containing two flexible daughter boards is fabricated, the structure of which is shown in Fig. 9D; then the panel is cut to obtain two flexible daughter boards, as shown in Fig. 9E.
  • the flexible daughter board produced by the method 1 is taken as an example to describe the manufacturing process of the rigid-flex printed circuit board according to the embodiment of the present invention.
  • the following examples are all described by taking a four-layer board as an example to make more layers.
  • the process of printed circuit boards is similar to this, and is no longer here - as an example.
  • the rigid sub-board is made of the first insulating substrate, and the flexible sub-board is made by the method provided in the first embodiment.
  • the manufacturing method of the embodiment includes the following steps:
  • Step 101 Perform windowing on the first insulating substrate e to obtain a window having the same outer shape as the flexible daughterboard and having a size slightly larger than the size of the flexible daughterboard, as shown in FIG. 11A;
  • Step 102 stacking processing, stacking sequence is: metal foil f ⁇ first insulating substrate ⁇ flexible daughterboard ⁇ metal foil f, as shown in FIG. 11B;
  • Step 103 a press-bonding process, as shown in FIG. 11C, the resin in the first insulating substrate is cured and cured with the resin in the second insulating substrate, and is integrally formed with the metal foil pressed on the surface;
  • Step 104 drilling process, as shown in FIG. 11D, except for the exposed portion of the flexible daughter board Performing a drilling process on the domain to obtain a through hole penetrating the cover film of the second insulating substrate and the flexible daughter board, and the flexible daughter board is electrically connected to the outer conductive layer through the through hole;
  • Step 105 metallizing, as shown in FIG. 11E, depositing a metallization layer on the outer surface of the metal foil and the inner wall of the through hole, wherein the metal layer and the metal foil together constitute the conductive layer of the rigid-flex printed circuit board ;
  • Step 106 graphics transfer processing, as shown in FIG. 11F, forming a line pattern on the conductive layer
  • Step 107 lamination processing, the stacking sequence is: metal foil f ⁇ third insulating substrate g ⁇ rigid-flex printed circuit board formed in step 106 ⁇ third insulating substrate g ⁇ metal foil f, see FIG. 11G Show
  • the third insulating substrate may be an insulating material formed by impregnating a resin (such as an epoxy resin, a phenol resin or a BT resin) with an electronic grade glass cloth or paper; or the like;
  • the resin may be in a B-Stage state, that is, a semi-cured state.
  • Step 108 a press-bonding process, as shown in FIG. 11H, the resin in the third insulating substrate bonds the metal foil to the rigid-flex printed circuit board formed in step 106 to form a whole;
  • Step 109 drilling processing and metallization processing, as shown in FIG. 111, forming a through hole penetrating the metal foil and the third insulating substrate on the rigid sub-board, and the rigid-flex printed circuit board formed in step 106 passes through the perforation Electrically connecting to the outer conductive layer;
  • Step 110 graphics transfer processing, as shown in FIG. 11J, forming a line pattern of the outer conductive layer
  • Step 111 surface treatment, that is, printing a solder mask h on the surface of the board, as shown in FIG. 11K, the solder mask prevents short circuit caused by moisture, chemicals, etc. between the conductive lines, and Short circuit, insulation and erosion against various harsh environments due to poor operation during assembly;
  • Step 112 the deep-depth cutting process, as shown in FIG. 11L, the deep-cut cutting is performed on the position corresponding to the exposed portion of the flexible daughter board of the board, and cut to the peelable protective film;
  • Step 113 removing the rigid cover, as shown in FIG. 11M, the rigid cover comprises a peelable protective film and an insulating material on the peelable protective film (including a second insulating substrate and a third insulating substrate), thereby forming the flexible daughter board Part of the area is exposed to facilitate bending.
  • Embodiment 4 the rigid sub-board still uses the first insulating substrate, and the flexible sub-board is still fabricated by the method provided in Embodiment 1.
  • the difference between this embodiment and the third embodiment is: For the processing, only the flexible daughter board is embedded in the window of the first insulating substrate, and the metal foil is not superimposed. Referring to FIG. 12, the rest of the processing is the same as that in the third embodiment. For details, refer to the description in the third embodiment. Let me repeat.
  • Embodiment 5 the rigid sub-board is made of a double-sided metal-clad board, and the flexible sub-board is still produced by the method provided in the first embodiment.
  • the difference between this embodiment and the third embodiment is:
  • the flexible sub-board is embedded in the window of the metal-clad board, and the metal foil is not superimposed.
  • the rest of the process is the same as that in the third embodiment.
  • the embodiment of the invention further provides a rigid-flex printed circuit made by the manufacturing method provided by the embodiment of the invention. Road board.
  • FIG. 11M a structure of a preferred four-layer rigid-flex printed circuit board according to an embodiment of the present invention is shown in FIG. 11M.

Abstract

本申请公开了一种刚挠结合印制电路板及其制作方法,用于解决现有刚挠结合印制电路板的制备过程中,容易导致挠性电路板与刚性电路板连接不良的问题。其方法包括:在挠性电路板表面预压合 B阶状态的第二绝缘基材,形成挠性子板;对刚性子板进行开窗,得到外形与挠性子板的外形相同且尺寸大于挠性子板的窗口;对刚性子板及挠性子板进行叠板,使挠性子板嵌入到窗口内;对叠板后的刚性子板及挠性子板进行压合,得到刚挠结合印制电路板;在挠性电路板上除需要裸露出的部分之外的区域内进行钻孔,得到贯穿第二绝缘基材的贯穿孔;对贯穿孔进行金属化处理,并制作外层导电层的线路图形;去除挠性电路板中需要裸露出的部分上的其他结构。

Description

一种刚挠结合印制电路板及其制作方法 本申请要求在 2013年 8月 1 日提交中国专利局、 申请号为 201310331777.1、 发明名 称为"一种刚挠结合印制电路板及其制作方法 "的中国专利申请的优先权, 其全部内容通过 引用结合在本申请中。 技术领域
本发明涉及印制电路板技术领域, 特别涉及一种刚挠结合印制电路板及其制作方法。 背景技术
印制电路板(Printed Circuit Board, PCB )是重要的电子部件, 一般用于承载电子元 器件以及实现电子元器件之间的电气连接。 随着电子技术的发展, 印制电路板的布线密度 越来越大, 且印制电路板的复杂度也越来越高。
按照所使用的绝缘材料强度不同, 印制电路板可分为刚性印制电路板、 挠性印制电路 板(Flexible Printed Circuit board, FPC )和刚挠结合印制电路板。 刚挠结合印制电路板是 指在一块印制电路板上既包含一个或多个刚性区, 又包含一个或多个挠性区的印制电路 板, 其作为一种刚性板和挠性板的结合体, 兼具刚性板与挠性板的优点。
由于挠性电路板具有可以自由弯曲、 卷绕、 折叠的特点, 因此, 由刚挠结合印制电路 板制成的产品易于组装, 并且能够折叠起来以形成一种较好的紧密封装形式, 从而省去了 电线、 电缆的连接安装, 减少了接插件与端点的焊接, 缩小了产品所占的空间及产品的重 量, 减少了电气千扰而提高了电气性能, 满足了电子设备朝着轻薄、 短小且多功能化方向 发展的需要。
目前, 刚挠结合印制电路板的制作过程如下: 先将挠性电路板 A1 与刚性电路板 A2 水平方向并排放置;再在该挠性电路板 A1与该刚性电路板 A2的上、下两个表面上配置半 固化片 A3 , 其中, 挠性电路板 A1的部分棵露(即该挠性电路板 A1中需要弯曲或折叠的 部分); 经过压合处理后, 半固化片 A3由半固化状态转化为完全固化状态, 从而将该挠性 电路板 A1 与该刚性电路板 A2连接在一起, 形成刚挠结合印制电路板, 其结构参见图 1 所示, 挠性电路板 A1通过图 1中所示的过孔与刚性电路板 A2外层的线路相连通。
由于挠性电路板的基材是由聚酰亚胺或者液晶聚合物构成, 具有优异的弯折性能, 但 是其刚性不足, 容易发生变形, 并且, 挠性电路板的厚度一般要比刚性电路板的厚度小很 多, 因此, 在进行压合处理时, 挠性电路板容易发生变形, 而与刚性电路板之间发生错位, 从而导致挠性电路板的导电层与刚性电路板的导电层连接不良, 甚至直接断开。
综上所述, 现有刚挠结合印制电路板的制备过程中, 容易导致挠性电路板的导电层与 刚性电路板的导电层连接不良, 甚至直接断开。 发明内容
本发明实施例提供了一种刚挠结合印制电路板及其制作方法, 用于解决现有刚挠结合 印制电路板的制备过程中, 容易导致挠性电路板的导电层与刚性电路板的导电层连接不 良, 甚至直接断开的问题。
本发明实施例提供了一种刚挠结合印制电路板的制作方法, 包括:
在挠性电路板表面预压合 B阶状态的第二绝缘基材, 形成挠性子板;
对刚性子板进行开窗, 得到外形与所述挠性子板的外形相同且尺寸大于所述挠性子板 的窗口;
对所述刚性子板及所述挠性子板进行叠板, 使所述挠性子板嵌入到所述窗口内; 对叠板后的所述刚性子板及所述挠性子板进行压合, 得到刚挠结合印制电路板; 在所述挠性电路板上除需要棵露出的部分之外的区域内进行钻孔, 得到贯穿所述第二 绝缘基材的贯穿孔, 所述贯穿孔用于连接所述挠性电路板的导电层与所述刚挠结合印制电 路板的导电层;
对所述贯穿孔进行金属化处理, 并制作外层导电层的线路图形;
去除所述挠性电路板中需要棵露出的部分上的其他结构。
优选的, 所述挠性子板的厚度与所述刚性子板的厚度的差值的绝对值不大于 50微米。 优选的, 所述窗口的尺寸与所述挠性子板的尺寸的差值的绝对值的取值范围为: 不小 于 10 米且不大于 100 米。
作为一种优选处理方式,若所述刚性子板为第一绝缘基材,所述进行叠板进一步包括: 在所述刚性子板及所述挠性子板的上表面和 /或下表面放置金属箔。
作为另一种优选处理方式, 若所述刚性子板为第一绝缘基材, 对所述贯穿孔进行金属 化处理还包括:
对压合得到的刚挠结合印制电路板表面进行金属化处理, 形成所述刚挠结合印制电路 板的导电层。
优选的, 若所述挠性电路板的表面还包含用于保护所述挠性电路板的覆盖膜, 则: 所述钻孔处理得到的贯穿孔还贯穿所述挠性电路板的覆盖膜。
在制作中, 对所述贯穿孔进行金属化处理, 具体包括:
在所述贯穿孔内填充导电膏; 或者,
对所述贯穿孔进行填孔电镀处理; 或者,
对所述贯穿孔进行电镀处理, 并在电镀后的贯穿孔内填充所述导电膏。
作为一种优选实现方式, 形成所述挠性子板具体包括: 在所述挠性电路板的需要棵露出的部分的表面压合可剥离保护膜; 以及 在压合有可剥离保护膜的挠性电路板的下表面预压合所述 B阶状态的第二绝缘基材, 其中, 所述预压合处理的温度高于常温且低于所述第二绝缘基材中的树脂的玻璃化温度。
作为另一种实现方式, 形成所述挠性子板具体包括:
在所述第二绝缘基材上与所述挠性电路板的需要棵露出的部分对应的位置上进行开 窗;
在该挠性电路板的表面对应预压合开窗处理后的第二绝缘基材, 该预压合处理的温度 高于常温且低于所述第二绝缘基材中的树脂的玻璃化温度; 以及
在所述第二绝缘基材的窗口内填充具有覆形作用的緩冲材料。
本发明实施例提供了一种刚挠结合印制电路板, 其中, 该刚挠结合印制电路板根据上 述方法制作而成。
本发明实施例中,在挠性电路板表面预压合 B阶状态的第二绝缘基材,形成挠性子板; 对刚性子板进行开窗处理, 得到外形与挠性子板的外形相同且尺寸大于该挠性子板的窗 口; 对刚性子板及挠性子板进行叠板, 使挠性子板嵌入到该窗口内; 对叠板后的刚性子板 及挠性子板进行压合, 得到刚挠结合印制电路板; 在挠性电路板上除需要棵露出的部分之 外的区域内进行钻孔, 得到贯穿第二绝缘基材的贯穿孔; 对该贯穿孔进行金属化处理, 并 制作外层导电层的线路图形; 去除挠性电路板中需要棵露出的部分上的其他结构。 由于挠 性子板不仅包括挠性电路板, 还包括覆盖于该挠性电路板的上表面及下表面的第二绝缘基 材, 因此, 该挠性子板具有一定的刚性, 在制作过程中不易变形, 从而提高了制作过程中 挠性子板与刚性子板的对位精度, 也提高了挠性电路板的导电层与刚性电路板的导电层的 电气连接可靠性。 附图说明
图 1为背景技术中刚挠结合印制电路板的结构示意图;
图 2为本发明提供的刚挠结合印制电路板的制作方法的流程图;
图 3A为本发明提供的釆用方式一对钻孔处理后得到的孔进行处理后的示意图; 图 3B为本发明提供的釆用方式二对钻孔处理后得到的孔进行处理后的示意图; 图 4为本发明提供的第一种制作挠性子板的方法流程图;
图 5为本发明提供的实施例一的方法流程图;
图 6A〜图 6G为釆用本发明提供的实施例一的方法制作挠性子板的过程中的剖面结构 示意图;
图 7为本发明提供的第二种制作挠性子板的方法流程图;
图 8为本发明提供的实施例二的方法流程图; 图 9A〜图 9E为釆用本发明提供的实施例二的方法制作挠性子板的过程中的剖面结构 示意图;
图 10为本发明提供的实施例三的方法流程图;
图 11A〜图 11M为釆用本发明提供的实施例三的方法制作刚挠结合印制电路板的过程 中的剖面结构示意图;
图 12为本发明提供的实施例四中叠板处理时各结构的剖面结构示意图。 具体实施方式
下面结合说明书附图对本发明实施例作进一步详细描述。
参见图 2所示,本发明实施例的一种刚挠结合印制电路板的制作方法, 包括以下步骤: 步骤 21、在挠性电路板表面预压合 B阶状态的第二绝缘基材, 形成挠性子板, 从而使 挠性电路板具有一定的刚性, 在后续制作过程中不易变形。
优选的,本步骤中形成的挠性子板的厚度与刚性子板的厚度的差值的绝对值不大于 50 微米( μιη ) , 从而在后续叠板及压合过程中避免了挠性电路板的导电层与刚性电路板的导 电层连接不良, 甚至直接断开。
步骤 22、对刚性子板进行开窗, 得到外形与挠性子板的外形相同且尺寸大于该挠性子 板的窗口。
在实施中, 本步骤中对刚性子板进行开窗可以釆用激光切割、 模具冲切或机械铣等处 理方式。
优选的, 本步骤中对刚性子板进行开窗形成的窗口的尺寸与步骤 21 中形成挠性子板 的尺寸的差值的绝对值的取值范围为: 不小于 10微米(μιη )且不大于 100微米 ( μιη ), 以使后续叠板时, 方便将挠性子板嵌入到该窗口内。
步骤 23、 对刚性子板及挠性子板进行叠板, 使挠性子板嵌入到刚性子板的窗口内。 步骤 24、 对叠板后的刚性子板及挠性子板进行压合, 得到刚挠结合印制电路板。 本步骤中, 由于挠性子板中的第二绝缘基材叠板时为 Β阶状态 (即半固化状态), 而 压合时的温度达到了第二绝缘基材中的树脂的玻璃化温度( TG ), 因此, 在压合过程中通 过该第二绝缘基材中的树脂可将挠性子板与刚性子板连接在一起, 并在压合之后, 由于第 二绝缘基材中的树脂的固化, 使得挠性子板与刚性子板粘合在一起而形成一个整体。
步骤 25、在挠性电路板上除需要棵露出的部分之外的区域内进行钻孔, 得到贯穿该第 二绝缘基材的贯穿孔, 其中, 该贯穿孔用于连接挠性电路板的导电层与刚挠结合印制电路 板的导电层;
具体的, 钻孔时可釆用激光钻孔、 机械钻孔或冲孔等方式。 本步骤得到的贯穿孔可以 为通孔, 也可以为盲孔。 进一步,若挠性子板的挠性电路板的表面还包含用于保护该挠性电路板的覆盖膜,则: 本步骤中, 进行钻孔得到的贯穿孔还贯穿该挠性电路板的覆盖膜。
步骤 26、对钻孔后得到的贯穿孔进行金属化处理, 并制作该刚挠结合印制电路板的外 层导电层的线路图形。
步骤 27、 去除挠性电路板中需要棵露出的部分上的其他结构, 以使挠性电路板中有一 部分能够棵露出来, 该棵露出来的部分挠性电路板能够弯折。
本步骤中, 可以釆用激光控深切割处理或机械控深铣处理, 去除挠性电路板中需要棵 露出的部分上的其他结构。
本发明实施例中, 由于挠性子板不仅包括挠性电路板, 还包括覆盖于该挠性电路板的 表面的第二绝缘基材, 因此, 该挠性子板具有一定的刚性, 在制作过程中不易变形, 从而 提高了制作过程中挠性子板与刚性子板的对位精度, 也提高了挠性电路板的导电层与刚性 电路板的导电层的电气连接可靠性。
下面对步骤 21中涉及到的技术名词进行说明。
一、挠性电路板一般包括挠性绝缘层以及覆盖于该挠性绝缘层的上表面和 /或下表面的 挠性导电层, 该挠性电路板可以为单面板或双面板; 优选的, 为了保护挠性电路板(尤其 是挠性电路板中的挠性导电层)不被外界侵蚀或损坏,挠性电路板的表面还设置有覆盖膜; 其中, 挠性导电层优选可以釆用压延铜箔或者电解铜箔等制作, 挠性绝缘层可以釆用聚酰 亚胺或者液晶聚合物等制作, 覆盖膜可以釆用聚酯 (PET )类、 聚酰亚胺(PI )类、 和 /或 聚氟(PTFE )类等材料制作, 优选的, 该覆盖膜釆用聚酰亚胺类材料制作。
二、 第二绝缘基材可以是由电子级的玻璃纤维布或者纸等浸渍于树脂 (如环氧树脂、 酚醛树脂或者 BT树脂等) 中而形成的绝缘性材料; 第二绝缘基材中的树脂可以处于 B阶 ( B-Stage )状态, 即半固化状态。
本发明实施例中, 步骤 26中对形成的贯穿孔进行金属化处理, 包括以下三种方式: 方式一、 对该贯穿孔进行填孔电镀处理, 以使该孔内的空间完全由电镀金属 m填充, 参见图 3 A所示;
优选的, 釆用电镀铜填充该孔。
方式二、 对该贯穿孔进行电镀处理, 并在电镀后的贯穿孔内填充导电膏; 具体的: 先对该贯穿孔的表面进行电镀处理, 再在电镀处理后的贯穿孔内填充能够导电的导电 膏 n, 以使该孔内的空间完全由导电膏 n填充, 参见图 3B所示;
优选的, 电镀处理包括沉铜电镀、 直接电镀、 真空溅镀后电镀等方式。
优选的, 导电膏可以是铜膏、 银膏或碳膏中的一种或至少两种的混合物。
方式三、 在该贯穿孔内直接填充导电膏;
优选的, 导电膏可以是铜膏、 银膏或碳膏中的一种或至少两种的混合物。 本发明实施例中, 刚性子板可以釆用第一绝缘基材, 也可以釆用覆金属板。
下面对第一绝缘基材及覆金属板进行说明。
一、 第一绝缘基材可以是由电子级的玻璃纤维布或者纸等浸渍于树脂 (如环氧树脂、 酚醛树脂或者 BT树脂等) 中而形成的绝缘性材料; 第一绝缘基材中的树脂可以处于 B阶 ( B-Stage )状态, 即半固化状态; 也可以处于 C阶( C-Stage )状态, 即完全固化状态。
二、覆金属板包括绝缘层以及覆盖于该绝缘层的至少一个表面(即上表面和 /或下表面) 的导电层; 覆金属板的制作过程依次包括以下步骤:
对绝缘基材进行开料处理; 在绝缘基材(该绝缘基材中的树脂处于 B阶状态)的上表 面和 /或表面覆以金属箔;对绝缘基材及金属箔进行压合处理,从而形成该覆金属板;其中, 由于压合处理的温度达到该绝缘基材中的树脂的玻璃化温度, 因此, 压合处理后该绝缘基 材中的树脂发生固化, 即由 B阶状态 (半固化状态)转化为 C阶状态 (完全固化状态); 进一步, 覆金属板可以为单面或双面覆金属玻璃纤维增强环氧树脂板、 单面或双面覆 金属聚四氟乙烯板、 单面或双面覆金属聚酰亚胺板、 单面或双面覆金属聚酰胺板、 单面或 双面覆金属氰酸盐树脂板或双面覆金属陶瓷板等。
作为一种实现方式, 若本发明实施例中的刚性子板釆用第一绝缘基材, 则步骤 23 中 对刚性子板及挠性子板进行叠板具体为:
在挠性子板嵌入到刚性子板的窗口内之后, 在该刚性子板及该挠性子板的上表面和 / 或下表面放置金属箔。
该实现方式下, 步骤 26 中可以釆用上述三种方式中任一方式对贯穿孔进行金属化处 理。
需要说明的是, 若釆用方式一及方式二对贯穿孔进行金属化处理时, 该刚性子板及该 挠性子板的上表面和 /或下表面放置的金属箔也会被电镀一层金属层,则刚挠结合印制电路 板的导电层由金属箔及电镀形成的金属层构成; 若釆用方式三对贯穿孔进行金属化处理 时, 则刚挠结合印制电路板的导电层仅由金属箔构成。
作为另一种实现方式, 若本发明实施例中的刚性子板釆用第一绝缘基材, 则步骤 23 中对刚性子板及挠性子板进行叠板不变, 即将挠性子板嵌入到刚性子板的窗口内。
基于该实现方式, 进一步, 在步骤 26中对贯穿孔进行金属化处理还包括:
对压合得到的刚挠结合印制电路板表面进行金属化处理, 形成刚挠结合印制电路板的 导电层。
该实现方式下, 步骤 26 中可以釆用上述方式一或方式二对贯穿孔进行金属化处理, 在金属化处理过程中, 该刚性子板及该挠性子板的表面会被电镀一层金属层, 则刚挠结合 印制电路板的导电层由电镀形成的金属层构成。
作为再一种实现形式, 若本发明实施例中的刚性子板为覆金属板, 则步骤 23 中对刚 性子板及挠性子板进行叠板时, 无需再在该刚性子板及该挠性子板的上表面或下表面放置 金属箔。
该实现方式下, 步骤 26 中可以釆用上述三种方式中的任一方式对贯穿孔进行金属化 处理。
需要说明的是, 若步骤 26 中釆用方式一及方式二对贯穿孔进行金属化处理时, 该刚 性子板及该挠性子板的表面会被电镀一层金属层, 则刚挠结合印制电路板的导电层由覆金 属板的导电层及电镀形成的金属层构成; 若步骤 26 中釆用方式三对贯穿孔进行金属化处 理时, 则刚挠结合印制电路板的导电层仅由覆金属板的导电层构成。
本发明实施例中, 挠性子板可以釆用以下任一方法制作:
方法一、 参见图 4所示, 该方法包括以下步骤:
步骤 41、 在挠性电路板的需要棵露出的部分的表面压合可剥离保护膜;
步骤 42、 在压合有可剥离保护膜的挠性电路板的表面预压合 B阶状态 (即半固化态) 的第二绝缘基材, 从而完成该挠性子板的制作, 该预压合处理的温度高于常温且低于该第 二绝缘基材中的树脂的玻璃化温度。
其中, 常温也被称为一般温度或室温, 一般是指 15 °C~25 °C。
进一步, 步骤 41中, 在挠性电路板上压合的可剥离保护膜的厚度为 5 ^ 米~50 ^ 米, 可釆用聚酯 (PET )类、 聚酰亚胺(PI )类、 和 /或聚氟(PTFE )类等材料制作。
进一步, 步骤 42 中, 预压合的第二绝缘基材与挠性电路板的厚度之和与刚性子板的 厚度的差值的绝对值不大于 5(H 米。
步骤 42 中, 预压合处理的温度宜高于常温, 但低于第二绝缘基材中的树脂的玻璃化 温度, 从而在预压合处理的过程中, 第二绝缘基材中的树脂经升温软化而更好地贴合在挠 性电路板的表面, 并由于预压合处理的温度低于树脂的玻璃化温度, 使树脂仍处于 B阶, 即不会发生固化, 以便于该第二绝缘基材的下一次压合固化。
优选的, 预压合处理的温度的取值范围在 60°C~150°C之间。
需要说明的是, 玻璃化温度( TG )是材料的一个重要特性参数, 材料的许多特性都在 玻璃化转变温度附近发生急剧的变化。 随着温度的升高, 该第二绝缘基材中的树脂先逐渐 软化, 当温度升至玻璃化温度时发生固化反应并且该过程不可逆, 即冷却后再次加热不会 发生形状的改变。 按玻璃化温度高低, 可将树脂分为普通 TG树脂和高 TG树脂, 普通 TG > 130度, 高 TG > 170度。 所以步骤 42中, 预压合处理的温度优选高于 60°C , 而针对普 通材料的树脂, 预压合处理的温度应低于 125 °C。
下面结合优选实施例对釆用方法一制作挠性子板的过程进行详细说明。
实施例一、 参见图 5所示, 本实施例包括以下步骤:
步骤 51、 开料处理, 即将原始挠性覆铜板切割成能够在生产线上进行制作的板子, 参 见图 6A所示;
步骤 52、 图形转移处理, 即形成挠性电路板的导电线路的图案, 参见图 6B所示; 步骤 53、 在挠性电路板的表面压合覆盖膜 a, 以保护该挠性电路板, 参见图 6C所示; 步骤 54、 切割可剥离保护膜 b , 切割后的可剥离保护膜 b的尺寸与该挠性电路板的需 要棵露出的部分的尺寸相同, 并将切割后的可剥离保护膜 b压合在该挠性电路板的需要棵 露出的部分上, 参见图 6D所示;
具体的, 切割方法包括激光切割、 模具冲切或机械铣。
步骤 55、 在挠性电路板的表面预压合第二绝缘基材 c, 使得第二绝缘基材 c与挠性电 路板的厚度之和与刚性子板的厚度的差值的绝对值不大于 50微米, 参见图 6E所示, 从而 完成了挠性子板的制作。
需要说明的是, 在实际生产中, 一般都需要批量制作挠性子板, 为了提高生产效率, 可一次性制作包含多个挠性子板的板子 ( panel ), 制作完成后, 根据需要切割成多个挠性 子板。 举例说明, 假设在生产时, 制作了包含两个挠性子板的 panel , 其结构参见图 6F所 示; 然后再对该 panel进行切割处理, 得到两个挠性子板, 参见图 6G所示。
方法二、 参见图 7所示, 该方法包括以下步骤:
步骤 71、 在第二绝缘基材的与挠性电路板需要棵露出的部分对应的位置上进行开窗, 得到的窗口的外形与该挠性电路板中需要棵露出的部分的外形相同且该窗口的尺寸与该 挠性电路板中需要棵露出的部分的尺寸相同;
具体的, 本步骤中可以釆用激光切割、 模具冲切或机械铣等方法进行开窗。
步骤 72、在该挠性电路板的表面(即上表面及下表面)预压合开窗后的第二绝缘基材, 该预压合处理的温度高于常温且低于第二绝缘基材中的树脂的玻璃化温度;
具体的, 预压合的第二绝缘基材与挠性电路板的厚度之和与刚性子板的厚度的差值的 绝对值不大于 50微米;
预压合处理的温度宜高于常温, 但低于第二绝缘基材中的树脂的玻璃化温度, 从而在 预压合处理的过程中, 第二绝缘基材中的树脂经升温软化而更好地贴合在挠性电路板的表 面, 并由于预压合处理的温度低于树脂的玻璃化温度, 使树脂仍处于 B阶, 即不会发生固 化, 以便于该第二绝缘基材的下一次压合固化; 优选的, 预压合处理的温度的取值范围在 60 °C ~150 °C之间。
步骤 73、在该第二绝缘基材的窗口内填充具有覆形作用的緩冲材料, 从而完成该挠性 子板的制作。
所谓覆形作用是指, 该材料可以与其相邻的材料在高温压合时紧密贴合, 无论与该材 料相邻的材料表面是光滑还是凹凸不平, 均能紧密贴合。 本发明实施例中, 緩冲材料与其 相邻的材料紧密贴合后, 该第二绝缘基材的窗口内被该緩冲材料完全填充。 优选的, 步骤 73 中填充的緩冲材料可以釆用硅胶片、 低密度聚乙烯等具有覆形作用 的材料。
下面结合优选实施例对釆用方法二制作挠性子板的过程进行详细说明。
实施例二、 参见图 8所示, 本实施例包括以下步骤:
步骤 81、 开料处理, 即将原始挠性覆铜板切割成能够在生产线上进行制作的板子, 参 见图 6A所示;
步骤 82、 图形转移处理, 即形成挠性电路板的导电线路的图案, 参见图 6B所示; 步骤 83、 在挠性电路板的上下两个表面压合覆盖膜 a, 以保护该挠性电路板, 参见图 6C所示;
步骤 84、在第二绝缘基材 c的与该挠性电路板的需要棵露出的部分对应的位置上进行 开窗, 得到的窗口的外形及尺寸与该挠性电路板中需要棵露出的部分的外形及尺寸均相 同, 参见图 9A所示;
步骤 85、 将开窗后的第二绝缘基材 c预压合在挠性电路板的表面, 使得第二绝缘基材 c与挠性电路板的厚度之和与刚性子板的厚度的差值的绝对值不大于 5(M 米, 参见图 9B 所示;
步骤 86、 在该第二绝缘基材 c的窗口内填充具有覆形作用的緩冲材料 d, 从而完成该 挠性子板的制作, 参见图 9C所示。
需要说明的是, 在实际生产中, 一般都需要批量制作挠性子板, 为了提高生产效率, 可一次性制作包含多个挠性子板的板子 ( panel ), 制作完成后, 根据需要切割成多个挠性 子板。 举例说明, 假设在生产时, 制作了包含两个挠性子板的 panel, 其结构参见图 9D所 示; 然后再对该 panel进行切割处理, 得到两个挠性子板, 参见图 9E所示。
下面以釆用方法一制作的挠性子板为例, 对本发明实施例的刚挠结合印制电路板的制 作过程进行详细说明, 以下实施例均以四层板为例进行说明, 制作更多层的印制电路板的 过程与此类似, 此处不再——举例说明。
实施例三、 本实施例中, 刚性子板釆用第一绝缘基材, 挠性子板釆用实施例一提供的 方法制作, 参见图 10所示, 本实施例的制作方法包括以下步骤:
步骤 101、 在第一绝缘基材 e上进行开窗处理, 得到外形与挠性子板的外形相同且尺 寸略大于挠性子板的尺寸的窗口, 参见图 11A所示;
步骤 102、 叠板处理, 叠板顺序为: 金属箔 f→第一绝缘基材→挠性子板→金属箔 f, 参见图 11B所示;
步骤 103、 压合处理, 参见图 11C所示, 第一绝缘基材中的树脂与第二绝缘基材中的 树脂粘合固化, 并与表面压合的金属箔形成一个整体;
步骤 104、 钻孔处理, 参见图 11D所示, 在挠性子板上除需要棵露出的部分之外的区 域上进行钻孔处理, 得到贯穿该第二绝缘基材及挠性子板的覆盖膜的贯穿孔, 挠性子板通 过该贯穿孔与外层导电层实现电气连接;
步骤 105、 金属化处理, 参见图 11E所示, 在金属箔的外表面及该贯穿孔的内壁沉积 金属化层, 其中, 金属层与金属箔共同组成该刚挠结合印制电路板的导电层;
步骤 106、 图形转移处理, 参见图 11F所示, 在导电层上形成线路图案;
步骤 107、 叠板处理, 叠板顺序为: 金属箔 f→第三绝缘基材 g→步骤 106形成的刚挠 结合印制电路板→第三绝缘基材 g→金属箔 f, 参见图 11G所示;
其中,第三绝缘基材可以是由电子级的玻璃纤维布或者纸等浸渍于树脂(如环氧树脂、 酚醛树脂或者 BT树脂等) 中而形成的绝缘性材料; 第三绝缘基材中的树脂可以处于 B阶 ( B-Stage )状态, 即半固化状态。
步骤 108、 压合处理, 参见图 11H所示, 第三绝缘基材中的树脂将金属箔与步骤 106 形成的刚挠结合印制电路板粘合在一起, 而形成一个整体;
步骤 109、 钻孔处理及金属化处理, 参见图 111所示, 在刚性子板上形成贯穿该金属 箔及第三绝缘基材的穿孔, 步骤 106形成的刚挠结合印制电路板通过该穿孔与外层导电层 实现电气连接;
步骤 110、 图形转移处理, 参见图 11J所示, 形成外层导电层的线路图案;
步骤 111、表面处理, 即在板子的表面印刷阻焊膜 h ( Solder Mask ), 参见图 11K所示, 该阻焊膜以防止导电线路之间因潮气、 化学品等原因引起的短路, 生产和装配过程中由于 不良操作而造成的短路、 绝缘以及抵抗各种恶劣环境的侵蚀等;
步骤 112、 控深切割处理, 参见图 11L所示, 在板子的挠性子板需要棵露出的部分对 应的位置上进行控深切割, 切割至可剥离保护膜;
步骤 113、 去除刚性盖, 参见图 11M所示, 该刚性盖包括可剥离保护膜及可剥离保护 膜上的绝缘材料(包括第二绝缘基材及第三绝缘基材), 从而将挠性子板的部分区域棵露 出来, 以便于弯折。
实施例四、 本实施例中, 刚性子板仍釆用第一绝缘基材, 挠性子板仍釆用实施例一提 供的方法制作, 本实施例与实施例三的区别在于: 在进行叠板处理时, 仅将挠性子板嵌入 到第一绝缘基材的窗口中, 不叠加金属箔, 参见图 12 所示, 其余处理过程与实施例三相 同, 具体参见实施例三的描述, 此处不再赘述。
实施例五、 本实施例中, 刚性子板釆用双面覆金属板, 挠性子板仍釆用实施例一提供 的方法制作, 本实施例与实施例三的区别在于: 在进行叠板处理时, 仅将挠性子板嵌入到 覆金属板的窗口中, 不叠加金属箔, 其余处理过程与实施例三相同, 具体参见实施例三的 描述, 此处不再赘述。
本发明实施例还提供了一种由本发明实施例提供的制作方法制得的刚挠结合印制电 路板。
具体的, 本发明实施例的一种优选的四层刚挠结合印制电路板的结构参见图 11M所 示。
需要说明的是, 附图中各结构的填充只是为了区别不同的结构, 不是对各结构的图案 或颜色的限定。
尽管已描述了本发明的优选实施例, 但本领域内的技术人员一旦得知了基本创造性概 念, 则可对这些实施例作出另外的变更和修改。 所以, 所附权利要求意欲解释为包括优选 实施例以及落入本发明范围的所有变更和修改。
显然, 本领域的技术人员可以对本发明进行各种改动和变型而不脱离本发明的精神和 范围。这样,倘若本发明的这些修改和变型属于本发明权利要求及其等同技术的范围之内, 则本发明也意图包含这些改动和变型在内。

Claims

权 利 要 求
1、 一种刚挠结合印制电路板的制作方法, 其特征在于, 所述方法包括:
在挠性电路板表面预压合 B阶状态的第二绝缘基材, 形成挠性子板;
对刚性子板进行开窗, 得到外形与所述挠性子板的外形相同且尺寸大于所述挠性子板 的窗口;
对所述刚性子板及所述挠性子板进行叠板, 使所述挠性子板嵌入到所述窗口内; 对叠板后的所述刚性子板及所述挠性子板进行压合, 得到刚挠结合印制电路板; 在所述挠性电路板上除需要棵露出的部分之外的区域内进行钻孔, 得到贯穿所述第二 绝缘基材的贯穿孔, 所述贯穿孔用于连接所述挠性电路板的导电层与所述刚挠结合印制电 路板的导电层;
对所述贯穿孔进行金属化处理, 并制作外层导电层的线路图形;
去除所述挠性电路板中需要棵露出的部分上的其他结构。
2、 如权利要求 1 所述的方法, 其特征在于, 所述挠性子板的厚度与所述刚性子板的 厚度的差值的绝对值不大于 5(H 米。
3、 如权利要求 1 所述的方法, 其特征在于, 所述窗口的尺寸与所述挠性子板的尺寸 的差值的绝对值的取值范围为: 不小于 10微米且不大于 100微米。
4、 如权利要求 1 所述的方法, 其特征在于, 若所述刚性子板为第一绝缘基材, 所述 进行叠板进一步包括:
在所述刚性子板及所述挠性子板的上表面和 /或下表面放置金属箔。
5、 如权利要求 1 所述的方法, 其特征在于, 若所述刚性子板为第一绝缘基材, 对所 述贯穿孔进行金属化处理还包括:
对压合得到的刚挠结合印制电路板表面进行金属化处理, 形成所述刚挠结合印制电路 板的导电层。
6、 如权利要求 1 所述的方法, 其特征在于, 若所述挠性电路板的表面还包含用于保 护所述挠性电路板的覆盖膜, 则:
所述钻孔处理得到的贯穿孔还贯穿所述挠性电路板的覆盖膜。
7、 如权利要求 1~6任一项所述的方法, 其特征在于, 对所述贯穿孔进行金属化处理, 具体包括:
在所述贯穿孔内填充导电膏; 或者,
对所述贯穿孔进行填孔电镀处理; 或者,
对所述贯穿孔进行电镀处理, 并在电镀后的贯穿孔内填充所述导电膏。
8、 如权利要求 1~6任一项所述的方法, 其特征在于, 形成所述挠性子板具体包括: 在所述挠性电路板的需要棵露出的部分的表面压合可剥离保护膜; 在压合有可剥离保护膜的挠性电路板的表面预压合所述 B阶状态的第二绝缘基材,其 中, 所述预压合处理的温度高于常温且低于所述第二绝缘基材中的树脂的玻璃化温度。
9、 如权利要求 1~6任一项所述的方法, 其特征在于, 形成所述挠性子板具体包括: 在所述第二绝缘基材上与所述挠性电路板的需要棵露出的部分对应的位置上进行开 窗;
在所述挠性电路板的表面对应预压合开窗处理后的第二绝缘基材, 所述预压合处理的 温度高于常温且低于所述第二绝缘基材中的树脂的玻璃化温度;
在所述第二绝缘基材的窗口内填充具有覆形作用的緩冲材料。
10、 一种刚挠结合印制电路板, 其特征在于, 所述刚挠结合印制电路板根据权利要求 1-9任一项所述方法制作而成。
PCT/CN2013/087886 2013-08-01 2013-11-27 一种刚挠结合印制电路板及其制作方法 WO2015014048A1 (zh)

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