JP2006100703A - Rigid-flexible substrate and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a rigid-flexible substrate in which a joint between the rigid and flexible substrates is strongly adhered, which comprises a simple process, and which provides a high material yield and a high product yield. <P>SOLUTION: A rigid substrate having a vertical wiring formed in a joint region and a flexible substrate having a connection terminal formed at an end are separately manufactured. The joint regions of the rigid substrate are spot faced deeper than the thickness of the flexible substrate to form steps. The connection terminals of the flexible substrate are connected to the vertical wirings of the steps. Another rigid substrate is laminated to cover the flexible substrate on the steps and the upper surface of the rigid substrate having the steps as the same plane. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a rigid-flexible substrate, and more particularly, a plurality of rigid substrates are interposed via a flexible substrate, and the principal surface of the flexible substrate is equal to the principal surface of the rigid substrate or more than the principal surface of the rigid substrate. The present invention relates to a method for manufacturing a rigid-flexible substrate connected to be lowered.

  In general, when a rigid board is disposed across a bent portion in a housing, the rigid board is divided into a plurality of pieces, and the divided rigid boards are connected with a connector or a flexible board. .

  However, connecting rigid boards with a connector or flexible board increases the height of the connector or flexible board, resulting in an obstacle to thinning the device. After connecting rigid boards, multiple rigid boards are connected. Productivity is reduced because the substrate cannot be processed or processed simultaneously.

  For this reason, a rigid-flexible substrate is used in which a plurality of rigid substrates having the same thickness are connected to each other so that both substrate surfaces are equal in height or the principal surface of the flexible substrate is lower than the principal surface of the rigid substrate.

  Such a rigid-flexible substrate is formed by a method disclosed in, for example, Japanese Patent Laid-Open No. 7-86749, that is, a conical shape made of a cured conductive composition protruding from a conductive metal plate such as an electrolytic copper foil. If a conductor bump is made to face another conductive metal plate through a heat-melting synthetic resin sheet and integrated by heating and pressing to make a double-sided board, many processes are required: become. In the following drawings, common portions are denoted by common reference numerals, and redundant description is omitted.

  In this method, first, as schematically shown in FIG. 19, a double-sided flexible substrate 2 in which only the edge portion is not covered with the cover film 1 is prepared. The portion of the flexible substrate 2 that is not covered with the cover film 1 is a portion that is laminated within the rigid substrate. In the figure, reference numeral 3 denotes a liquid crystal polymer film, 4 denotes a horizontal wiring portion (conductor pattern), and 5 denotes a vertical wiring portion (conductor bump).

The vertical wiring part 5 is formed by the following method using a conductor bump.
That is, a conical conductor bump is formed on the electrolytic copper foil that becomes the horizontal wiring portion 4 by patterning in a later step, and this conductive bump is connected to another electrolytic copper foil via a liquid crystal polymer film (synthetic resin sheet) 3. And these are integrated by heating and pressing. At this time, the tips of the conductor bumps are pressed against the pair of electrolytic copper foils, and the tips are plastically deformed into a truncated cone shape to form the vertical wiring portion 5 connecting the horizontal wiring portions 4 on both sides. The horizontal wiring part 4 is formed by applying a resist to each electrolytic copper foil surface, exposing through a mask pattern, removing the unexposed part by development, and etching the exposed part of the electrolytic copper foil. .

  The cover film 1 is formed by applying a resist to the substrate surface after the etching process and removing only the portion integrated with the rigid substrate by photolithography.

  Next, this flexible substrate 2 is integrated with a laminate 6 (symbol 7 is a release film) having conductor bumps 5a separately produced, schematically shown in FIG. Become.

The laminate 6 is formed by the following method.
That is, a conical conductor bump is formed on the electrolytic copper foil to be the horizontal wiring portion 4 by etching in a later process, and this conductor bump is passed through another glass-epoxy prepreg (synthetic resin sheet) 3a. It arrange | positions facing the electrolytic copper foil 4a, and is integrated by heating and pressurization. At this time, the front end of the conductor bump is pressed against the electrolytic copper foil 4a, and the front end is plastically deformed into a truncated cone, thereby forming the vertical wiring portion 5 that connects the electrolytic copper foils 4a on both sides. Next, the horizontal wiring portion 4 is formed by patterning the electrolytic copper foil on one side. Further, a conductor bump 5a is formed at a position corresponding to the vertical wiring portion 5 of the horizontal wiring portion 4, laminated with a glass-epoxy prepreg (synthetic resin sheet) 3a with the conductor bump 5a side inside, and heated. While being integrated by pressurization, the tip of the conductor bump 5a is protruded from the synthetic resin sheet 3a.

  The laminate 6 and the flexible substrate 2 are integrated by aligning the protruding side of the conductor bump 5a with the exposed surface side of the horizontal wiring portion 4 of the flexible substrate 2 (the side without the cover film 1), and heating. This is done by pressing (FIG. 21). At this time, a slit 8 is formed at the boundary between the laminate 6 and the flexible substrate 2, and a release film 7 that also serves as a spacer is interposed on the surface of the flexible substrate 2 that contacts the cover film 1.

  Further, the flexible substrate 2 side of the laminate 9 is laminated with a separately produced laminate 10 schematically shown in FIG. 22 and integrated by heating and pressing to form a laminate 11 (FIG. 23).

Integration of the laminated body 9 and the laminated body 10 is performed as follows.
That is, the protruding conductor bump 5a of the laminated body 10 is brought into contact with a predetermined horizontal wiring portion 4 of the laminated body 9 (flexible substrate 2), and the surface of the laminated body 9 (flexible substrate 2) that is in contact with the cover film 1 is placed on the surface. Then, the laminate 10 and the laminate 9 are overlapped with the release film 7 also serving as a spacer, and heated and pressurized, whereby the laminate 11 having the eight horizontal wiring portions 4 schematically shown in FIG. can get.

Thereafter, as schematically shown in FIG. 24, an outer horizontal wiring portion (outer layer pattern) 4 is formed by patterning, and an insulating protective coating 12 is applied with a resist or the like. Finally, as schematically shown in FIG. Then, the cover portions A and B covering the flexible substrate 2 are removed to complete the rigid-flexible substrate.
JP-A-7-86749

  As described above, in the conventional rigid-flexible substrate manufacturing method, in order to laminate the flexible substrate 2 between the layers of the rigid substrate (the main surface of the flexible substrate is equal to or lower than the main surface of the rigid substrate). Therefore, there is a difficulty that requires a large number of steps.

  Further, in this method, a plurality of small unit substrates are usually formed in one large substrate, and the large substrate is laminated and formed, so that a rigid substrate flexible substrate is disposed. The portion where the rigid substrate of the portion or the flexible substrate is to be disposed is punched and becomes waste, and there is a problem that the yield of the material is low.

  In addition, since a plurality of unit rigid-flexible substrates are formed on one large substrate, if a defect occurs in a portion corresponding to one of the unit substrates of the synthetic resin sheet or the laminate in the preparation process, the whole is defective. There was also a problem that the yield rate was low.

  The rigid-flexible substrate of the present invention is a rigid-flexible substrate in which a rigid substrate and a flexible substrate are connected to solve the above-described problem, and the rigid substrate is connected to the flexible substrate. The flexible substrate is connected to the rigid substrate at the step portion, and the flexible substrate on the step portion is covered with another rigid substrate.

  More specifically, the rigid-flexible substrate of the present invention is a rigid-flexible substrate in which a rigid substrate and a flexible substrate are connected, and the rigid substrate has a connection terminal at an upper portion at a connection portion with the flexible substrate. The flexible substrate has a connection terminal on an end surface thereof, and the connection terminal is connected to the connection terminal of the step portion of the rigid substrate so as to be integrally bonded to the step portion of the rigid substrate. The flexible substrate on the step portion is covered with another rigid substrate.

  In the rigid-flexible substrate of the present invention, it is preferable that the other rigid substrate covers not only the flexible substrate on the stepped portion but also the upper surface of the rigid substrate having the stepped portion. By doing so, the mounting area can be widened.

  Further, when the other rigid substrate covers only the stepped portion, the upper surface of the other rigid substrate is substantially equal to or lower than the upper surface of the rigid substrate having the stepped portion. It is desirable that If the upper surface of another rigid substrate covering the stepped portion is raised and protrudes, the protruding portion becomes an obstacle to mounting when set on a mounting machine, which is not preferable.

  The rigid-flexible board manufacturing method of the present invention is a rigid-flexible board manufacturing method in which a plurality of rigid boards are connected via a flexible board, and has a connection terminal in a region connected to the rigid board. A step of creating a flexible substrate, a step of creating a rigid substrate having a step portion deeper than the thickness of the flexible substrate from which the vertical wiring portion is exposed, and a step of forming the flexible substrate on the vertical wiring portion of the step portion of each rigid substrate. A step of electrically and mechanically connecting the terminals, and laminating another rigid substrate on the connection portion of the flexible substrate and the upper surface of the rigid substrate, and forming a horizontal wiring portion on at least the uppermost surface, Forming a rigid substrate portion having a wiring portion in which a horizontal wiring portion is connected by a vertical wiring portion. And wherein the door.

  Moreover, you may perform the process of carrying out the thermocompression bonding of another rigid board | substrate so that the said flexible substrate may be covered on the connection part of the flexible substrate of a step part instead of the said last process.

  Note that the step of creating a rigid substrate having a step portion deeper than the thickness of the flexible substrate from which the vertical wiring portion serving as a connection terminal is exposed is specifically the region where the flexible substrate is connected. A step of creating a plurality of rigid boards having a vertical wiring part connected to a horizontal wiring part at a position to be connected or a position lower than the position, and a countersink process is performed on a region to which the flexible board of each rigid board is connected. And a step of forming a step deeper than the thickness of the flexible substrate where the vertical wiring portion is exposed.

  Further, as another step of creating a rigid substrate having a step portion deeper than the thickness of the flexible substrate from which the vertical wiring portion is exposed, a position where the flexible substrate is connected to a region where the flexible substrate is connected or this A step of forming a plurality of inner layer rigid substrates having vertical wiring portions connected to horizontal wiring portions at a position of the inner layer, and an exterior to expose a region to which the flexible substrate is connected on the main surface of the inner layer rigid substrate And a step of attaching a substrate to form a step portion deeper than the thickness of the flexible substrate.

  It is desirable that the rigid substrate has an inspection terminal on its lower surface, and the connection terminal of the step portion of the rigid substrate is connected by a metal plating layer and / or a solidified conductive paste.

  Moreover, the connection terminal of the step part of a flexible substrate can be formed from the solidified material of a metal wiring, a metal plating layer, or an electrically conductive paste.

  The vertical wiring portion to which the connection terminal of the flexible substrate of the rigid substrate is connected can be formed by connecting conductor bumps in the thickness direction of the substrate, but can also be formed by via holes or through holes. Further, the connection terminals connected to the vertical wiring portion of the rigid substrate of the flexible substrate can also be formed with conductor bumps, but can also be configured with other terminals such as high-temperature solder or electrolytic copper foil.

  In the present invention, the conductor bumps used for the rigid wiring board, the vertical wiring portion of the flexible board, and the connection terminal of the flexible board are usually formed on the conductive metal layer. Examples of such a conductive metal layer include a conductive sheet (foil) such as an electrolytic copper foil. The conductive metal layer may be a single sheet or a patterned sheet. The shape is not particularly limited, and the conductor bumps may be formed not only on one main surface but also on both main surfaces.

  Conductive bumps are, for example, conductive powders such as silver, gold, copper, solder powder, alloy powders or composite (mixed) metal powders, and polycarbonate resins, polysulfone resins, polyester resins, phenoxy resins, phenol resins, polyimide resins, etc. It is comprised with the electroconductive composition prepared by mixing binder components, such as these, or an electroconductive metal. When the conductive bump is formed of a conductive composition, a bump having a high aspect ratio can be formed by, for example, a printing method using a relatively thick metal mask. About 400 μm is desirable, and the height of the conductor bump may be appropriately mixed with the height that can penetrate one layer of the synthetic resin sheet and the height that can penetrate a plurality of layers of the synthetic resin sheet. As means for forming a conductive bump with a conductive metal, (a) a fine metal soul having a certain shape or size is spread on a conductive metal layer surface on which an adhesive layer has been provided in advance, and is selectively fixed. (This may be done by placing a mask), (b) A plating resist is printed and patterned on the surface of the electrolytic copper foil, and copper, tin, gold, silver, solder, etc. are plated to selectively make a minute metal Forming columns (bumps); (c) applying and patterning a solder resist on the surface of the conductive metal layer; and dipping in a solder bath to selectively form minute metal columns (bumps); (d) metal plate A part of the film is coated with a resist and etched to form a fine metal bump. Here, the fine metal soul or the fine metal pillar corresponding to the conductor bump may have a multilayer structure or a multilayer shell structure in which different metals are combined. For example, copper may be cored and the surface may be coated with a gold or silver layer to provide oxidation resistance, or copper may be cored and the surface may be coated with a solder layer to provide solder jointability. In the present invention, when the conductive bump is formed of a conductive composition, the process can be further simplified as compared with the case where the conductive bump is formed by means such as plating, which is effective in terms of cost reduction.

  In the present invention, as the synthetic resin-based sheet constituting the insulating layer of the rigid substrate or flexible substrate into which the conductor bumps are inserted, for example, a thermoplastic resin film (sheet) or a thermosetting resin sheet held in a state before curing is used. The thickness is preferably about 50 to 300 μm. Here, examples of the thermoplastic resin sheet include sheets such as polycarbonate resin, polysulfone resin, thermoplastic polyimide resin, tetrafluoropolyethylene resin, hexafluoropolypropylene resin, and polyetheretherketone resin. In addition, the thermosetting resin sheet held in the pre-curing state includes epoxy resin, bismaleimide triazine resin, polyimide resin, phenol resin, polyester resin, melamine resin, or butadiene rubber, butyl rubber, natural rubber, neoprene rubber, silicone. Examples thereof include raw rubber sheets such as rubber. These synthetic resins may be used alone or may contain insulating inorganic or organic fillers, and sheets made of glass cloth or mat, organic synthetic fiber cloth or mat, or a sheet combined with a reinforcing material such as paper. There may be.

  Furthermore, in the present invention, a plurality of layers having a structure in which the main surface of the synthetic resin sheet is in contact with the main surface of the conductive metal layer in which the conductor bumps are formed in order to form a rigid substrate or a flexible substrate are laminated. When heating and pressurizing the laminated body, the base (pad) on which the synthetic resin sheet is placed is used as a metal plate or heat-resistant resin plate, such as stainless steel plate, brass plate, polyimide resin, with little size and deformation. A plate (sheet), a polytetrafluoroethylene resin plate (sheet), or the like is used.

  According to the method for manufacturing a printed wiring board according to the present invention, a rigid-flexible substrate can be created by a simple method in which a flexible substrate and a rigid substrate are separately manufactured and connected to each other, greatly increasing the production process. Can be simplified. In addition, since the rigid substrate and the flexible substrate can be connected in a state where the final form has been created, there is no flexible substrate in the rigid substrate, and there is a process such as removing the rigid substrate from only the flexible substrate. Therefore, the utilization efficiency of the material can be improved. In addition, since each of the rigid substrate and the flexible substrate can be judged as good or bad in the almost completed unit substrate state before connection, loss can be minimized even if a defect occurs in the production process.

  Moreover, since it coat | covers with another rigid board | substrate so that the flexible substrate upper surface of the connection part may be covered, the adhesive strength of this part can be raised while improving the mechanical strength of a connection part.

  Further, since the connection portion is covered so as not to protrude, the flatness of the component mounting surface of the board, which is important in the subsequent mounting process, can be ensured without impairing the appearance.

  Furthermore, since the other rigid substrate covers the substrate including the connection portion between the flexible substrate and the rigid substrate as the same plane, the mounting area can be widened.

  Next, an embodiment of the present invention will be described with reference to FIGS. 1 to 18, the same reference numerals are given to the portions common to FIGS. 19 to 23, and a duplicate description is omitted.

(Create flexible substrate)
First, an electrolytic copper foil (4a) having a thickness of 18 μm was adhered to both sides of a polyimide film 3 (PI) having a thickness of 25 μm to form a through hole TH at a predetermined position of the substrate to obtain a double-sided copper-clad flexible substrate.

  A normal etching resist ink (trade name, PSR-4000 H, Taiyo Ink KK) is screen-printed on the electrolytic copper foil 4a on both sides of this double-sided copper-clad laminate, masking the conductor pattern, and then cupric chloride. After performing an etching treatment using as a etchant, the resist mask was peeled off to obtain a double-sided flexible substrate 20 shown in FIG. Reference numeral 4 denotes a horizontal wiring portion obtained by patterning the electrolytic copper foil 4a by etching. Further, the cover film 1 was formed by photolithography on the horizontal wiring portion 4 except for the vicinity of the through hole TH of the double-sided flexible substrate 20.

  Next, as shown in FIG. 2, a conductor bump 5a is formed on the portion of the horizontal wiring portion 4 connected to the through hole TH, and a glass-epoxy prepreg (synthetic resin sheet) 3a having a thickness of 60 μm is formed thereon. Abutting and placing between an aluminum foil and a rubber sheet between, for example, a hot plate kept at 100 ° C., heating and pressurizing at 1 MPa for about 1 minute, the tip of the conductor bump 5a is a glass-epoxy prepreg (synthetic resin A flexible substrate 21 protruding from the system sheet 3a was prepared.

  The flexible substrate 21 shown in FIG. 2 is for connecting the two rigid substrates shown in FIG. 4, and this flexible substrate 21 is made up of a large number of substrates in one large substrate. 2 is completed and is divided into individual flexible boards and connected to the rigid board.

(Rigid board creation)
As a B2it (B Square It: registered trademark) except that the glass-epoxy prepreg (synthetic resin sheet) 3a before curing having a thickness of 60 μm is used instead of the polyimide film 3 (PI) described above. 3 using the double-sided rigid substrate having the same structure as that of the flexible substrate shown in FIGS. 1 and 2 by a known method described in, for example, Japanese Patent Laid-Open No. 8-204332. A rigid substrate 22 having the horizontal wiring portion 4 was prepared.

  This rigid substrate 22 has the same structure as the rigid substrate portion of the laminate 11 shown in FIG. 23 except that the insulating layers of each layer are all made of glass-epoxy prepreg (synthetic resin sheet) 3a. .

  The rigid substrate 22 shown in FIG. 3 is also prepared by making a large number of substrates in a large substrate and forming it up to the state shown in FIG. Divided into individual rigid substrates.

(Rigid-Flexible board creation)
In the state of a large substrate before being divided into individual rigid substrates, or after being divided into individual rigid substrates, a countersink process is performed in the vicinity of the vertical wiring portion 5 connected to the flexible substrate of each rigid substrate 22, The rigid board | substrate 23 which has the step part S where the vertical wiring part 5 was exposed by sweeping deeper than the thickness of the flexible substrate 20 which should be connected was created (FIG. 4).

  Next, the unit rigid board | substrate 23 and the unit flexible board | substrate 21 which were divided | segmented separately are arrange | positioned so that it may become a final form in a frame. Usually, the frame is of such a size that a plurality of rigid-flexible substrates can be assembled.

  The conductor bumps of the counter-sinking part may be sandwiched between copper wirings, but the counter-sink part may be free of copper wiring in order to expose the conductor bump part on the surface in consideration of the precision of the counter-sinking in the depth direction. . Further, in order to obtain a stepped shape, it is also possible to form the step by laminating a portion to be a step in a rigid substrate forming process by removing in advance by router processing or the like.

  FIGS. 5 to 7 show another method for manufacturing a rigid substrate having such a stepped portion, in which a laminated plate 50a above the stepped portion and a laminated plate 50b constituting a portion below the stepped portion are shown in advance. Are separately prepared (FIG. 5), and when laminated with the laminated plate 50b at the end of the laminated plate 50a, the portion that becomes the step S of the laminated plate 50b is cut (FIG. 6), and these are positioned and heated. By pressing, a rigid substrate 50 having a stepped portion S can be formed (FIG. 7).

  In FIG. 8, the rigid substrate 23 in which the stepped portion S is formed in the frame body 24 is disposed so that the stepped portion S faces each other, and the flexible substrate 21 straddles the stepped portion S of each rigid substrate 23. This is an example in which the is fixed temporarily. In this embodiment, small projections 25 whose overall width is substantially the same as the width of the holding portion of the frame body 24 are formed on the outer periphery of each rigid substrate 23, and the rigid substrate disposed in the frame body 24. 23 is held and fixed in the frame 24 by the small protrusion 25. In addition, you may make it temporarily fix this small protrusion 25 to the inner surface of the frame 24 with an adhesive agent as needed.

  Further, as shown in FIG. 9, a T-shaped projection 26 is provided at the edge of the rigid board 23, and a recess 27 is provided at the corresponding position on the inner surface of the frame 24 to fit the projection. The rigid substrate 23 may be held on the frame body by a mating structure.

  In this way, a rigid body in which a plurality of frame bodies 24 holding a plurality of rigid substrates 23 and flexible substrates 21 in a positional relationship in a final form are stacked and integrated by heating and pressing and fixed to the frame body 24. -A flexible substrate is obtained.

  Thereafter, each rigid-flexible substrate is punched out, and the state shown in FIG. 10 is obtained.

  In this embodiment, a method of manufacturing a rigid-flexible substrate in which two rigid substrates are connected by one flexible substrate has been described. However, the present invention is not limited to the number of rigid substrates and flexible substrates. .

  Further, as shown in FIG. 11, a plurality of sets of vertical wiring portions connected to different horizontal wiring portions 4 are formed on the side portion of one rigid substrate 23, and step portions having different depths for each wiring are formed. You may make it connect with a separate flexible substrate in each step part. Further, stepped portions may be formed on different sides of the rigid substrate and connected to the flexible substrate.

  In addition, although the above example demonstrated the example which formed the vertical wiring part (connection terminal) of the rigid board | substrate to which a flexible substrate is connected with a conductor bump, this invention is not limited to this Example, It is also possible to fill the via hole 28a shown in FIG. 12 with a conductive paste 28b. Further, as shown in FIG. 13, a conductor bump 29 is formed by high-temperature solder (for example, solder having a melting point of about 200 ° C. to 240 ° C.), and terminals 27 (substantially the same as the horizontal wiring portion 4) formed on the stepped portion of the rigid substrate 23. To the same device). In this case, it is possible to avoid remelting of the connecting solder between the flexible substrate and the rigid substrate by using a solder having a melting point lower than that of the above-described high-temperature solder when mounting the electronic component. Alternatively, the insulating layer can be made conductive by drilling holes with a laser or the like, embedding a conductive paste in the insulating layer, and then laminating.

  Furthermore, as a connection between the flexible substrate and the rigid substrate, (a) a method of connecting by sandwiching an anisotropic conductive film, (b) gold plating is applied to each terminal of the flexible substrate and the rigid substrate, Connection is also possible by a method of crimping connection, (c) a method of connecting by insulating hot layers filled with a conductive paste and vacuum hot pressing.

(Coating of the upper surface of the connection part of the flexible substrate)
In this embodiment, the upper surface of the connecting portion of the rigid-flexible substrate formed in the above process, for example, in the state shown in FIG. 10 is covered with another rigid substrate 30.

  FIG. 14 shows an embodiment in which a double-sided wiring rigid board is stacked as another rigid board 30 and a wiring portion can be formed over the entire upper surface of the rigid substrate including the upper surface of the connecting portion of the flexible substrate. . In the same figure, the part shown below the thick line AA shows the rigid-flexible substrate in the state shown in FIG. According to this embodiment, not only the mechanical strength of the connection portion is increased, but also the wiring layer can be formed on the connection portion of the flexible substrate, so that the degree of freedom in design is increased.

  FIG. 15 shows the rigid-flexible substrate of FIG. 10 with the upper surface of the rigid-flexible substrate connected to another rigid substrate 30 (insulating substrate having no wiring portion) through an uncured glass-epoxy prepreg (synthetic resin sheet) 3a. 3 shows an embodiment in which the substrate is coated so as to be lower than the substrate surface of the rigid substrate 23 and integrated by thermocompression bonding. In the figure, the portion of the substrate shown in FIG. 10 is outlined and simplified.

  16 and 17 schematically show a state in which the BB cross section in FIG. 15 is viewed in the longitudinal direction of the flexible substrate. FIG. 16 shows an example in which the width of the step portion is made substantially equal to the width of the flexible substrate, and the widths of the other rigid substrates 30 are also made substantially equal so that the flexible substrate and the rigid substrate 30 are fitted to the step portion. FIG. 17 shows an example in which the width of the stepped portion is made wider than the width of the flexible substrate, and both ends of the other rigid substrate 30 are directly bonded to the stepped portion, and the flexible substrate is pressed against the stepped portion by the rigid substrate. It is. As shown in FIG. 17, when the width of the rigid substrate 30 is made wider than the width of the flexible substrate, the flexible substrate is more firmly fixed to the stepped portion.

  In the embodiment shown in FIGS. 15 to 17, the upper surface of the rigid substrate 30 is lower than the substrate surface of the rigid substrate 23, but the upper surfaces of the other rigid substrates 30 are the upper surfaces of the rigid substrate 23 as shown in FIG. 18. You may make it become almost level. In this case, the component mounting area on the rigid board is substantially increased. In addition, since the upper surface of the rigid substrate 30 is substantially level with the upper surface of the rigid substrate 23, the flatness of the component mounting surface can be ensured. Such flatness of the component surface is important, for example, when screen printing of solder cream on the component mounting surface. If the upper surface of the rigid substrate 30 is high, the screen surface for printing comes into contact with the upper surface of the rigid substrate 30 and is rigid. Although it does not adhere to the upper surface of the substrate 23 and becomes an obstacle to printing, if the upper surface of the rigid substrate 30 is at a substantially equal or lower position, such an obstacle does not occur. By the way, even if a solder resist film of about 50 μm is usually present on a rigid substrate, it does not impede practically screen printing. Therefore, the range in which the upper surface of the rigid substrate 30 can be practically almost equal to the rigid substrate 23 is as follows: Usually, it is 100 micrometers or less, Preferably it is 50 micrometers or less.

  When manufacturing rigid-flexible substrates, the rigid substrate and flexible substrate can be manufactured in separate processes, and after both are divided into unit substrates, the rigid substrate and flexible substrate can be manufactured, which greatly simplifies the production process. And there are few parts which become waste, and a yield can be improved by using a material effectively. In addition, since it is possible to determine pass / fail for each unit substrate and perform the final connection process using only non-defective products, it is possible to minimize waste even if a defect occurs in the substrate manufacturing process. Furthermore, since the connecting portion between the rigid substrate and the flexible substrate is covered with another rigid substrate, the mechanical strength and adhesive force of the connecting portion can be increased, and the flatness of the substrate can be ensured. In addition, when an ordinary multilayer double-sided wiring board is laminated on a substrate including the connecting portion, the mounting area increases and the degree of design freedom increases.

Sectional drawing which shows typically the double-sided type flexible substrate used for manufacture of a rigid-flexible substrate. Sectional drawing which shows typically the state which provided the conductor bump in the flexible substrate of FIG. Sectional drawing which shows typically the rigid board | substrate used for manufacture of a rigid-flexible board | substrate. Sectional drawing which shows typically the state which gave the countersink process to the flexible substrate connection part of the rigid board | substrate of FIG. The figure for demonstrating the manufacturing method of the rigid board | substrate which has a step part. The figure for demonstrating the manufacturing method of the rigid board | substrate which has a step part. The figure for demonstrating the manufacturing method of the rigid board | substrate which has a step part. The top view which shows the state which incorporated the unit rigid board | substrate and the unit flexible board | substrate in the frame. The top view which shows a part of engaging part of a frame and a unit rigid board | substrate. Sectional drawing which shows typically the rigid-flexible board | substrate used for coating | covering the connection part of a flexible substrate. The perspective view which shows the step part provided in the rigid board | substrate. Sectional drawing which shows the state of the connection part of a rigid board | substrate and a flexible substrate typically. Sectional drawing which shows the state of the connection part of a rigid board | substrate and a flexible substrate typically. Sectional drawing which shows typically the state which coat | covered the connection part of the flexible substrate, and the whole surface of the rigid board | substrate with the other rigid board | substrate. Sectional drawing which shows typically the state which coat | covered the flexible substrate on a step part with another rigid board | substrate. Sectional drawing which shows the BB cross section in FIG. 15 typically. Sectional drawing which shows the BB cross section in FIG. 15 typically. Sectional drawing which shows typically the state which coat | covered the connection part of the flexible substrate with the other rigid board | substrate. Sectional drawing which shows typically the flexible substrate used for manufacture of the conventional rigid-flexible substrate. Sectional drawing which shows typically the laminated body laminated | stacked with the flexible substrate of FIG. Sectional drawing which shows typically the laminated body which laminated | stacked the flexible substrate of FIG. 19, and the laminated body of FIG. Sectional drawing which shows typically the laminated body laminated | stacked with the laminated body of FIG. Sectional drawing which shows typically the laminated body which laminated | stacked the laminated body of FIG. 21 and the laminated body of FIG. FIG. 24 is a cross-sectional view schematically showing a laminate in which the outer layer of the laminate in FIG. 23 is patterned. Sectional drawing which shows a rigid-flexible board | substrate typically.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Cover film, 2 ... Double-sided type flexible substrate which is not coat | covered 3 ... Polyimide film, 3a ... Glass-epoxy type prepreg (synthetic resin type sheet), 4 ... Horizontal wiring part (conductor pattern), 4a ... electrolytic copper foil, 5 ... vertical wiring part (conductor bump), 5a ... conductor bump, 6, 9, 10, 11 ... laminated body, 8 ... slit, 12 ... insulating protective coating, 20, 21 ... flexible substrate, 22, DESCRIPTION OF SYMBOLS 23 ... Rigid board | substrate, 24 ... Frame, 25 ... Small protrusion, 26 ... Projection part, 27 ... Recessed part, 28 ... Via hole, 29 ... Conductor bump by high temperature solder, TH ... Through hole, 30 ... Other rigid board | substrates.

Claims (13)

A rigid-flexible board in which a rigid board and a flexible board are connected,
The rigid substrate has a step portion at a connection portion with the flexible substrate, the flexible substrate is connected to the rigid substrate at the step portion, the flexible substrate on the step portion, and an upper surface of the rigid substrate Is a rigid-flexible substrate which is covered with another rigid substrate. A rigid-flexible board in which a rigid board and a flexible board are connected,
The rigid substrate has a step portion having a connection terminal at an upper portion in a connection portion with the flexible substrate, and the flexible substrate has a connection terminal on an end surface, and the connection terminal is connected to a step portion of the rigid substrate. It is electrically connected to the connection terminal and is integrally bonded to the step portion of the rigid substrate, and the flexible substrate on the step portion and the upper surface of the rigid substrate are covered with another rigid substrate. A rigid-flexible substrate characterized by the above. A rigid-flexible board in which a rigid board and a flexible board are connected,
The rigid substrate has a step portion at a connection portion with the flexible substrate, the flexible substrate is connected to the rigid substrate at the step portion, and the flexible substrate on the step portion is another rigid substrate. A rigid-flexible substrate, characterized in that it is coated. A rigid-flexible board in which a rigid board and a flexible board are connected,
The rigid substrate has a step portion having a connection terminal at an upper portion in a connection portion with the flexible substrate, and the flexible substrate has a connection terminal on an end surface, and the connection terminal is connected to a step portion of the rigid substrate. Rigid-flexible, characterized in that it is electrically connected to a connection terminal and is integrally bonded to a step portion of the rigid substrate, and the flexible substrate on the step portion is covered with another rigid substrate. substrate.   5. The rigid-flexible substrate according to claim 3, wherein an upper surface of the other rigid substrate is substantially level with an upper surface of the rigid substrate having the stepped portion.   The connection terminal of the step portion of the rigid substrate is connected to an inspection terminal formed on the lower surface thereof by a metal plating layer and / or a solidified material of a conductive paste. A rigid-flexible substrate according to item 1.   The rigid-flexible substrate according to any one of claims 1 to 6, wherein the connection terminal of the flexible substrate is made of a metal wiring, a metal plating layer, or a solidified conductive paste. The electrical connection between the connection terminal of the step portion of the rigid substrate and the connection terminal of the flexible substrate is as follows:
Connected with conductive paste, anisotropic conductive film, high-temperature solder, gold plating applied to the surface of each terminal, or solid bumps of conductive composition or conductive bumps made of conductive metal The rigid-flexible substrate according to any one of claims 1 to 7, wherein the rigid-flexible substrate is formed.   The connection terminals of the rigid board and the flexible board are connected to a horizontal wiring portion of each of the boards, and are connected to an inspection terminal provided on the opposite surface of the rigid board. The rigid-flexible substrate according to any one of 1 to 8. In a manufacturing method of a rigid-flexible substrate in which a rigid substrate and a flexible substrate are connected,
Creating a flexible substrate having a connection terminal in a region connected to the rigid substrate;
Creating a rigid substrate having a step portion deeper than the thickness of the flexible substrate in which the vertical wiring portion serving as a connection terminal is exposed;
The terminals of the flexible substrate are electrically and mechanically connected to the vertical wiring portion, which is the connection terminal of the step portion of each rigid substrate, and another rigid portion is connected to the upper portion of the flexible substrate and the upper surface of the rigid substrate. And a step of forming a rigid substrate portion having a wiring portion in which a horizontal wiring portion is formed on at least the uppermost surface and each horizontal wiring portion is connected by a vertical wiring portion. A method for manufacturing a rigid-flexible substrate. In a manufacturing method of a rigid-flexible substrate in which a rigid substrate and a flexible substrate are connected,
Creating a flexible substrate having a connection terminal in a region connected to the rigid substrate;
Creating a rigid substrate having a step portion deeper than the thickness of the flexible substrate in which the vertical wiring portion serving as a connection terminal is exposed;
A terminal of the flexible substrate is electrically and mechanically connected to the vertical wiring portion which is a connection terminal of a step portion of each rigid substrate, and the flexible substrate is covered on the connection portion of the flexible substrate of the step portion. And a step of thermocompression bonding another rigid substrate. A method for producing a rigid-flexible substrate, comprising: The step of creating a rigid substrate having a step portion deeper than the thickness of the flexible substrate in which the vertical wiring portion serving as the connection terminal is exposed,
Creating a plurality of rigid substrates having a vertical wiring portion connected to a horizontal wiring portion at a position where the flexible substrate is connected or at a position of an inner layer from the region where the flexible substrate is connected;
Forming a stepped portion deeper than the thickness of the flexible substrate where the vertical wiring portion is exposed by applying a countersink process to a region of the rigid substrate to which the flexible substrate is connected. Item 12. A method for producing a rigid-flexible substrate according to Item 10 or 11. The step of creating a rigid substrate having a step portion deeper than the thickness of the flexible substrate in which the vertical wiring portion serving as the connection terminal is exposed,
Creating a plurality of inner layer rigid substrates having a vertical wiring portion connected to a horizontal wiring portion at a position where the flexible substrate is connected or an inner layer position in the region where the flexible substrate is connected;
Forming a rigid substrate having a step deeper than the thickness of the flexible substrate by exposing a region to which the flexible substrate is connected to the main surface of the inner layer rigid substrate and attaching an exterior substrate. The method for producing a rigid-flexible substrate according to claim 10 or 11, wherein:

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