WO2014065172A1 - Substrat flexible - Google Patents

Substrat flexible Download PDF

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Publication number
WO2014065172A1
WO2014065172A1 PCT/JP2013/078061 JP2013078061W WO2014065172A1 WO 2014065172 A1 WO2014065172 A1 WO 2014065172A1 JP 2013078061 W JP2013078061 W JP 2013078061W WO 2014065172 A1 WO2014065172 A1 WO 2014065172A1
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WO
WIPO (PCT)
Prior art keywords
line
axis direction
dielectric
signal line
conductor
Prior art date
Application number
PCT/JP2013/078061
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English (en)
Japanese (ja)
Inventor
祐貴 若林
Original Assignee
株式会社村田製作所
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Filing date
Publication date
Application filed by 株式会社村田製作所 filed Critical 株式会社村田製作所
Publication of WO2014065172A1 publication Critical patent/WO2014065172A1/fr

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0277—Bendability or stretchability details
    • H05K1/028—Bending or folding regions of flexible printed circuits
    • H05K1/0281—Reinforcement details thereof
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0213—Electrical arrangements not otherwise provided for
    • H05K1/0216—Reduction of cross-talk, noise or electromagnetic interference
    • H05K1/0218—Reduction of cross-talk, noise or electromagnetic interference by printed shielding conductors, ground planes or power plane
    • H05K1/0219—Printed shielding conductors for shielding around or between signal conductors, e.g. coplanar or coaxial printed shielding conductors
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/14—Structural association of two or more printed circuits
    • H05K1/148—Arrangements of two or more hingeably connected rigid printed circuit boards, i.e. connected by flexible means
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/22—Secondary treatment of printed circuits
    • H05K3/28—Applying non-metallic protective coatings
    • H05K3/281—Applying non-metallic protective coatings by means of a preformed insulating foil

Definitions

  • the present invention relates to a flexible substrate, and more particularly to a flexible substrate having flexibility.
  • the high-frequency signal line includes a dielectric element body, a signal line, and two ground conductors.
  • the dielectric body is configured by laminating a plurality of dielectric sheets made of a flexible material, and extends linearly in a predetermined direction.
  • the signal line is a linear conductor provided on the dielectric sheet.
  • the two ground conductors are provided on the dielectric sheet and sandwich the signal line in the stacking direction. Thereby, the signal line and the two ground conductors form a stripline structure.
  • the high-frequency signal line is used, for example, for connecting two circuit boards in an electronic device.
  • the high-frequency signal line described in Patent Document 1 is used by being bent in an electronic device. At the portion where the high-frequency signal line is bent, tensile stress or compressive stress is applied to the signal line. When a large tensile stress is applied to the signal line, the signal line may be disconnected. On the other hand, when a large compressive stress is applied to the signal line, the signal line may buckle and peel off from the inner dielectric sheet.
  • an object of the present invention is to provide a flexible substrate that can suppress the disconnection of the linear conductor and the separation of the linear conductor from the dielectric layer during bending.
  • the flexible substrate according to the first embodiment of the present invention is a flexible laminate that is configured by laminating an insulating layer made of a plurality of types of materials and is folded, and in the folded position, the lamination direction A laminate having an asymmetric structure with respect to a straight line passing through the center of the laminate in a direction perpendicular to the stacking direction, and a position where the stack is bent and a position overlapping the neutral surface of the stack in the stacking direction. And a linear first conductor.
  • the flexible substrate according to the second aspect of the present invention is configured by laminating a plurality of insulator layers, and bends a flexible laminate, and a second conductor provided in the laminate.
  • the body and the second conductor have an asymmetric structure with respect to a straight line passing through the center in the stacking direction in a direction perpendicular to the stacking direction at the bent position.
  • FIG. 1 is an external perspective view of a flexible substrate according to a first embodiment. It is an exploded view of the dielectric body of the flexible substrate 10 of FIG.
  • FIG. 3 is a cross-sectional structural view of the flexible substrate taken along AA in FIG. 2. It is a sectional structure figure of a layered product used for calculation of a neutral plane.
  • FIG. 3 is a cross-sectional structural view of the flexible substrate taken along BB in FIG. 2. It is an external appearance perspective view of the high frequency signal track concerning a 2nd embodiment.
  • FIG. 7 is an exploded view of a dielectric element body of the high-frequency signal line in FIG. 6. It is sectional structure drawing of the edge part vicinity of the positive direction side of the line part of a high frequency signal line.
  • FIG. 1 is an external perspective view of a flexible substrate 10 according to the first embodiment.
  • FIG. 2 is an exploded view of the dielectric body 12 of the flexible substrate 10 of FIG.
  • FIG. 3 is a cross-sectional structural view of the flexible substrate 10 along AA in FIG. In FIG. 2, only the configuration of the main part of the flexible substrate 10 is shown, and the configuration other than the main part is omitted.
  • the stacking direction of the flexible substrate 10 is defined as the z-axis direction.
  • the direction in which the long side of the flexible substrate 10 extends is defined as the x-axis direction
  • the direction in which the short side of the flexible substrate 10 extends is defined in the y-axis direction. It is defined as
  • the flexible substrate 10 is a transmission / reception circuit provided with an antenna in an electronic device such as a mobile phone. As shown in FIGS. 1 and 2, the flexible substrate 10 includes a dielectric body 12, an antenna unit 70, a connection unit 72, and a signal line 74.
  • the dielectric body 12 is a rectangular plate member having flexibility, and is configured by laminating a plurality of insulator layers made of a plurality of types of materials.
  • the dielectric body 12 is configured by laminating the protective layer 14 and the dielectric sheets 18a and 18b in this order from the positive direction side to the negative direction side in the z-axis direction. It is a laminated body.
  • the main surface on the positive side in the z-axis direction of the dielectric body 12 is referred to as the front surface
  • the main surface on the negative direction side in the z-axis direction of the dielectric body 12 is referred to as the back surface.
  • the dielectric body 12 is bent at two locations as shown in FIG. More specifically, as shown in FIG. 2, the dielectric element body 12 is bent at a valley line L21 and a mountain line L22 that extend in the y-axis direction in the vicinity of the center in the x-axis direction.
  • the valley line L21 is located closer to the positive direction side in the x-axis direction than the mountain line L22.
  • the valley line L21 is a line where the surface of the dielectric body 12 is valley-folded.
  • the mountain line L22 is a line on which the surface of the dielectric body 12 is folded.
  • the dielectric sheets 18a and 18b have the same shape as the dielectric body 12 when viewed in plan from the z-axis direction.
  • the dielectric sheets 18a and 18b are made of a flexible thermoplastic resin such as polyimide or liquid crystal polymer.
  • the front surface the main surface on the positive side in the z-axis direction of the dielectric sheets 18a and 18b
  • the main surface on the negative direction side in the z-axis direction of the dielectric sheets 18a and 18b is referred to as the back surface.
  • the antenna unit 70 is formed on the surface of the dielectric sheet 18a, and is provided in the vicinity of the short side of the dielectric sheet 18a on the positive side in the x-axis direction.
  • the antenna unit 70 is an antenna configured by, for example, a spiral coil pattern.
  • the connecting portion 72 is formed on the surface of the dielectric sheet 18a, and is provided in the vicinity of the short side of the dielectric sheet 18a on the negative side in the x-axis direction.
  • the connection part 72 is a land electrode on which a connector is mounted, for example.
  • the signal line 74 is a linear conductor that transmits a high-frequency signal and is provided in the dielectric body 12.
  • the signal line 74 is formed on the surface of the dielectric sheet 18b, and connects the antenna unit 70 and the connection unit 72 via a via hole conductor (not shown). Further, the signal line 74 intersects the valley line L21 and the mountain line L22.
  • the signal line 74 is made of, for example, a metal material having a small specific resistance mainly composed of silver or copper.
  • the protective layer 14 is an insulating layer exposed on the surface of the dielectric body 12, and covers substantially the entire surface of the dielectric sheet 18a.
  • the protective layer 14 has an opening Hi.
  • the connecting portion 72 is exposed to the outside through the opening Hi.
  • the protective layer 14 is made of a resist material, for example, an epoxy resin.
  • the dielectric element body 12 has a straight line L0 passing through the center in the z-axis direction of the dielectric element body 12 in the y-axis direction at the bent positions (the valley line L21 and the mountain line L22).
  • An asymmetric structure means a structure that is not line symmetric with respect to the straight line L0.
  • the flexible substrate 10 has the following structure in order to prevent the signal line 74 from being disconnected and the signal line 74 from being separated from the dielectric sheet 18b during bending.
  • the signal line 74 overlaps with the neutral surface S ⁇ b> 1 of the dielectric body 12 in the z-axis direction at the bent positions (that is, the valley line L ⁇ b> 21 and the mountain line L ⁇ b> 22).
  • the neutral plane is an imaginary plane in which neither compressive strain nor tensile strain is generated during bending of the beam.
  • the thickness of the protective layer 14 and the thickness of the dielectric sheets 18a and 18b are designed so that the boundary between the dielectric sheet 18a and the dielectric sheet 18b becomes a neutral plane.
  • line 74 is formed on the surface of the dielectric material sheet 18b, and the dielectric body 12 is formed. Thereby, the signal line 74 is provided at a position where the signal line 74 overlaps with the neutral surface S1 of the dielectric element body 12 in the z-axis direction at the bent positions (that is, the valley line L21 and the mountain line L22).
  • FIG. 4 is a cross-sectional structure diagram of the stacked body 300 used for calculation of the neutral plane.
  • FIG. 5 is a cross-sectional structural view of the flexible substrate 10 along BB in FIG.
  • the stacking direction is defined as the Y-axis direction.
  • the positive direction side in the Y-axis direction is the downward direction in the stacking direction as shown in FIG.
  • the stacked body 300 is configured by stacking n insulating layers.
  • the Young's modulus of the i-th layer is Ei and the Y coordinate of the boundary between the i-th insulator layer and the i + 1-th insulator layer is li
  • the Y-coordinate Y0 of the neutral plane is It is represented by Formula (1).
  • the dielectric sheets 18a and 18b are made of a liquid crystal polymer.
  • the Young's modulus of the liquid crystal polymer used in this embodiment is 7 GPa.
  • the total thickness of the dielectric sheet 18a and the dielectric sheet 18b is 50 ⁇ m.
  • the protective layer 14 is made of an epoxy resin.
  • the Young's modulus of the epoxy resin used in this embodiment is 2.5 GPa.
  • the thickness of the protective layer 14 is 20 ⁇ m. And if the said value is substituted to Formula (1), it will become like the following formula
  • the neutral surface S ⁇ b> 1 of the dielectric body 12 is 29.375 ⁇ m from the surface of the dielectric body 12. Therefore, in the flexible substrate 10 according to the present embodiment, the signal line 74 is disposed so as to overlap the position of 29.375 ⁇ m from the surface of the dielectric element body 12.
  • the signal line 20 for example, a copper foil having a thickness of 10 ⁇ m to 20 ⁇ m
  • 74 can be disposed so as to overlap the position of 29.375 ⁇ m from the surface of the dielectric body 12.
  • the signal line 74 hardly generates compressive stress and tensile stress.
  • the signal line 74 is prevented from being disconnected and the signal line 74 from being peeled off from the dielectric sheet 18b.
  • compressive stress and tensile stress are hardly applied to the signal line 74, the expansion and contraction of the signal line 74 is suppressed, and the variation in the line width and thickness of the signal line 74 is suppressed. As a result, fluctuations in the characteristic impedance of the signal line 74 are suppressed.
  • the neutral plane S1 in the present embodiment is a neutral plane in a state where the signal line 74 is not provided (including the protective layer 14). That is, in the flexible substrate 10, the position of the neutral surface S1 of the dielectric body 12 is calculated in a state where the signal line 74 is not provided, and the signal line 74 is arranged so as to overlap the neutral surface S1 in the z-axis direction. is doing.
  • dielectric sheets 18a and 18b made of a thermoplastic resin having a copper foil (metal film) formed on the entire surface of one main surface are prepared. Specifically, a copper foil is attached to one main surface of the dielectric sheets 18a and 18b. Furthermore, the surface of the copper foil of the dielectric sheets 18a and 18b is smoothed by, for example, applying zinc plating for rust prevention.
  • the dielectric sheets 18a and 18b are liquid crystal polymers.
  • the thickness of the copper foil is 10 ⁇ m to 20 ⁇ m.
  • the antenna unit 70 and the connection unit 72 are formed on the surface of the dielectric sheet 18a as shown in FIG. Specifically, a resist having the same shape as the antenna unit 70 and the connection unit 72 shown in FIG. 2 is printed on the copper foil on the surface of the dielectric sheet 18a. And the copper foil of the part which is not covered with the resist is removed by performing an etching process with respect to copper foil. Thereafter, the resist is removed by spraying a cleaning liquid. Thereby, as shown in FIG. 2, the antenna part 70 and the connection part 72 are formed on the surface of the dielectric sheet 18a by a photolithography process. In this step, a conductor such as a signal line or a ground conductor other than the antenna unit 70 and the connection unit 72 may be formed.
  • the signal line 74 is formed on the surface of the dielectric sheet 18b.
  • the formation process of the signal line 74 is the same as the formation process of the antenna part 70 and the connection part 72, description is abbreviate
  • a signal line other than the signal line 74 or a conductor such as a ground conductor may be formed.
  • a through hole is formed by irradiating a laser beam to a position where a via hole conductor (not shown) of the dielectric sheet 18a is formed. Then, the through-hole is filled with a conductive paste to form a via hole conductor (not shown).
  • the dielectric sheets 18a and 18b are stacked and pressure-bonded in this order from the positive direction side in the z-axis direction to the negative direction side.
  • the dielectric sheets 18a and 18b are subjected to heat treatment and pressure treatment. As a result, the dielectric sheet 18a and the dielectric sheet 18b are fused.
  • a protective layer 14 is formed on the surface of the dielectric sheet 18a by applying a resin (resist) paste by screen printing. Thereby, the flexible substrate 10 shown in FIG. 1 is obtained.
  • FIG. 6 is an external perspective view of the high-frequency signal transmission line 10a according to the second embodiment.
  • FIG. 7 is an exploded view of the dielectric body 12 of the high-frequency signal transmission line 10a of FIG.
  • FIG. 8 is a cross-sectional structure diagram in the vicinity of the end portion on the positive direction side of the line portion 12a of the high-frequency signal line 10a.
  • the stacking direction of the high-frequency signal transmission line 10a is defined as the z-axis direction.
  • the longitudinal direction of the high-frequency signal transmission line 10a is defined as the x-axis direction, and the direction orthogonal to the x-axis direction and the z-axis direction is defined as the y-axis direction.
  • the high-frequency signal line 10a is a flexible substrate used for connecting two high-frequency circuits in an electronic device such as a mobile phone. As shown in FIGS. 6 and 7, the high-frequency signal line 10a includes a dielectric body 12, external terminals 16a and 16b, signal lines 20, ground conductors 22 and 24, via-hole conductors b1, b2, B1 to B4, and a connector 100a. , 100b.
  • the dielectric body 12 is a flexible plate-like member that extends in the x-axis direction when viewed in plan from the z-axis direction, and includes a line portion 12 a, a connection portion 12 b, 12c is included.
  • the dielectric body 12 is a laminated body in which a protective layer 14 and dielectric sheets 18a to 18c are laminated in this order from the positive side in the z-axis direction to the negative side. is there.
  • the main surface on the positive side in the z-axis direction of the dielectric body 12 is referred to as the front surface
  • the main surface on the negative direction side in the z-axis direction of the dielectric body 12 is referred to as the back surface.
  • the line portion 12a extends in the x-axis direction. Further, a valley line L1 and a mountain line L2 extending in the y-axis direction exist in the vicinity of the end portion on the positive direction side in the x-axis direction of the line portion 12a.
  • the valley line L1 is located on the positive side in the x-axis direction from the mountain line L2.
  • the line portion 12a is bent so that the back surface of the line portion 12a forms a valley.
  • the line part 12a is bent so that the back surface of the line part 12a forms a mountain.
  • a valley line L3 and a mountain line L4 extending in the y-axis direction exist in the vicinity of the end on the negative direction side in the x-axis direction of the line portion 12a.
  • the valley line L3 is located closer to the negative side in the x-axis direction than the mountain line L4.
  • the line portion 12a is bent so that the back surface of the line portion 12a forms a valley.
  • the line portion 12a is bent so that the back surface of the line portion 12a forms a mountain.
  • the connecting portions 12b and 12c are respectively connected to the negative end portion in the x-axis direction and the positive end portion in the x-axis direction of the line portion 12a, and have a rectangular shape.
  • the width in the y-axis direction of the connection parts 12b and 12c is larger than the width in the y-axis direction of the line part 12a.
  • the dielectric sheets 18a to 18c extend in the x-axis direction when viewed in plan from the z-axis direction, and have the same shape as the dielectric body 12.
  • the dielectric sheets 18a to 18c are sheets made of flexible thermoplastic resin such as polyimide or liquid crystal polymer.
  • the front surface the main surface on the positive side in the z-axis direction of the dielectric sheets 18a to 18c
  • the main surface on the negative direction side in the z-axis direction of the dielectric sheets 18a to 18c is referred to as the back surface.
  • the dielectric sheet 18a includes a line portion 18a-a and connection portions 18a-b and 18a-c.
  • the dielectric sheet 18b includes a line portion 18b-a and connecting portions 18b-b and 18b-c.
  • the dielectric sheet 18c includes a line portion 18c-a and connection portions 18c-b and 18c-c.
  • the line portions 18a-a, 18b-a, and 18c-a constitute the line portion 12a.
  • the connecting portions 18a-b, 18b-b, and 18c-b constitute a connecting portion 12b.
  • the connecting portions 18a-c, 18b-c, and 18c-c constitute a connecting portion 12c.
  • the signal line 20 is a linear conductor that transmits a high-frequency signal and is provided in the dielectric body 12.
  • the signal line 20 is a linear conductor that is formed on the surface of the dielectric sheet 18 b and extends in the x-axis direction along the dielectric element body 12.
  • the end of the signal line 20 on the negative direction side in the x-axis direction is located at the center of the connecting portion 18b-b as shown in FIG.
  • the end of the signal line 20 on the positive side in the x-axis direction is located at the center of the connecting portion 18b-c.
  • the signal line 20 is made of a metal material having a small specific resistance mainly composed of silver or copper.
  • the signal line 20 is formed on the surface of the dielectric sheet 18b means that the signal line 20 is formed by patterning a metal foil formed by plating on the surface of the dielectric sheet 18b, This indicates that the signal line 20 is formed by patterning the metal foil attached to the surface of the dielectric sheet 18b.
  • the surface roughness of the surface of the signal line 20 that is in contact with the dielectric sheet 18b is the surface roughness of the surface of the signal line 20 that is not in contact with the dielectric sheet 18b. It becomes larger than the surface roughness.
  • the ground conductor 22 is provided on the positive side in the z-axis direction from the signal line 20, and is a solid conductor layer extending in the x-axis direction along the signal line 20. It is. More specifically, the ground conductor 22 is formed on the surface of the dielectric sheet 18a and faces the signal line 20 through the dielectric sheet 18a. Thus, the ground conductor 22 is provided on the surface side of the dielectric body 12 with respect to the signal line 20. In the present embodiment, the ground conductor 22 is not provided with an opening or the like at a position overlapping the signal line 20. That is, the ground conductor 22 is a solid conductor extending in the x-axis direction along the signal line 20.
  • the ground conductor 22 is made of a metal material having a small specific resistance mainly composed of silver or copper.
  • the ground conductor 22 is formed on the surface of the dielectric sheet 18a means that the ground conductor 22 is formed by patterning a metal foil formed by plating on the surface of the dielectric sheet 18a, This indicates that the ground conductor 22 is formed by patterning the metal foil attached to the surface of the dielectric sheet 18a.
  • the surface roughness of the surface of the ground conductor 22 that is in contact with the dielectric sheet 18a is the surface roughness of the surface of the ground conductor 22 that is not in contact with the dielectric sheet 18a. It becomes larger than the surface roughness.
  • the ground conductor 22 is constituted by a line portion 22a and terminal portions 22b and 22c.
  • the line portion 22a is provided on the surface of the line portion 18a-a and extends along the x-axis direction.
  • the terminal portion 22b is provided on the surface of the line portion 18a-b and forms a rectangular ring.
  • the terminal portion 22b is connected to the end portion on the negative direction side in the x-axis direction of the line portion 22a.
  • the terminal portion 22c is provided on the surface of the connection portion 18a-c and forms a rectangular ring.
  • the terminal portion 22c is connected to the end portion on the positive direction side in the x-axis direction of the line portion 22a.
  • the ground conductor 24 is provided on the negative side in the z-axis direction from the signal line 20, and is a solid conductor layer extending in the x-axis direction along the signal line 20. It is. More specifically, the ground conductor 24 is formed on the surface of the dielectric sheet 18c and faces the signal line 20 through the dielectric sheet 18b. Accordingly, the ground conductor 24 is provided on the back surface side of the dielectric element body 12 with respect to the signal line 20. In the present embodiment, the ground conductor 24 is not provided with an opening or the like at a position overlapping the signal line 20. That is, the ground conductor 24 is a solid conductor that extends in the x-axis direction along the signal line 20.
  • the ground conductor 24 is made of a metal material having a small specific resistance mainly composed of silver or copper.
  • the ground conductor 24 is formed on the surface of the dielectric sheet 18c means that the ground conductor 24 is formed by patterning a metal foil formed by plating on the surface of the dielectric sheet 18c, This indicates that the ground conductor 24 is formed by patterning the metal foil attached to the surface of the dielectric sheet 18c.
  • the surface roughness of the surface of the ground conductor 24 that is in contact with the dielectric sheet 18c is the surface roughness of the surface of the ground conductor 24 that is not in contact with the dielectric sheet 18c. It becomes larger than the surface roughness.
  • the ground conductor 24 includes a line portion 24a and terminal portions 24b and 24c.
  • the line portion 24a is provided on the surface of the line portion 18c-a, and extends along the x-axis direction.
  • the terminal portion 24b is provided on the surface of the line portion 18c-b and forms a rectangular ring.
  • the terminal portion 24b is connected to the end portion on the negative direction side in the x-axis direction of the line portion 24a.
  • the terminal portion 24c is provided on the surface of the connection portion 18c-c and forms a rectangular ring.
  • the terminal portion 24c is connected to the end portion on the positive direction side in the x-axis direction of the line portion 24a.
  • the signal line 20 is sandwiched between the ground conductors 22 and 24 from both sides in the z-axis direction, as shown in FIG. As a result, the signal line 20 and the ground conductors 22 and 24 form a triplate stripline structure.
  • the external terminal 16a is a rectangular conductor formed at the center on the surface of the connecting portion 18a-b. Therefore, the external terminal 16a overlaps the end of the signal line 20 on the negative direction side in the x-axis direction when viewed in plan from the z-axis direction.
  • the external terminal 16b is a rectangular conductor formed at the center on the surface of the connecting portion 18a-c. Therefore, the external terminal 16b overlaps the end portion of the signal line 20 on the positive direction side in the x-axis direction when viewed in plan from the z-axis direction.
  • External terminals 16a and 16b are made of a metal material having a small specific resistance mainly composed of silver or copper. Further, Ni / Au plating is applied to the surfaces of the external terminals 16a and 16b. Here, the external terminals 16a and 16b are formed on the surface of the dielectric sheet 18a. The metal foil formed by plating on the surface of the dielectric sheet 18a is patterned to form the external terminals 16a and 16b. It indicates that the external terminals 16a and 16b are formed by patterning the metal foil attached to the surface of the dielectric sheet 18a.
  • the surface roughness of the surface where the external terminals 16a and 16b are in contact with the dielectric sheet 18a is the same as that of the external terminals 16a and 16b. It becomes larger than the surface roughness of the non-contact surface.
  • External terminals 16a and 16b, signal line 20, ground conductor 22, and ground conductor 24 have substantially the same thickness.
  • the thicknesses of the external terminals 16a and 16b, the signal line 20, the ground conductor 22, and the ground conductor 24 are, for example, 10 ⁇ m to 20 ⁇ m.
  • the plurality of via-hole conductors B1 pass through the dielectric sheet 18a in the z-axis direction on the positive side in the y-axis direction from the signal line 20, and are equally spaced in a line in the x-axis direction.
  • the plurality of via-hole conductors B2 pass through the dielectric sheet 18b in the z-axis direction on the positive side in the y-axis direction from the signal line 20, and are equally spaced in a line in the x-axis direction.
  • Via-hole conductors B1 and B2 are connected to each other to form one via-hole conductor.
  • the end of the via-hole conductor B1 on the positive side in the z-axis direction is connected to the ground conductor 22.
  • the end of the via-hole conductor B2 on the negative direction side in the z-axis direction is connected to the ground conductor 24.
  • the via-hole conductors B1 and B2 are formed by filling the via holes formed in the dielectric sheets 18a and 18b with a conductive paste mainly composed of silver, tin, copper, or the like and solidifying them.
  • the plurality of via-hole conductors B3 pass through the dielectric sheet 18a in the z-axis direction on the negative side in the y-axis direction from the signal line 20, and are equally spaced in a line in the x-axis direction. Are lined up.
  • the plurality of via-hole conductors B4 pass through the dielectric sheet 18b in the z-axis direction on the negative side in the y-axis direction from the signal line 20, and are evenly spaced in a line in the x-axis direction.
  • the via-hole conductors B3 and B4 constitute one via-hole conductor by being connected to each other.
  • the end of the via-hole conductor B3 on the positive side in the z-axis direction is connected to the ground conductor 22.
  • the end of the via-hole conductor B4 on the negative side in the z-axis direction is connected to the ground conductor 24.
  • the via-hole conductors B3 and B4 are formed by filling the via holes formed in the dielectric sheets 18a and 18b with a conductive paste mainly composed of silver, tin, copper, or the like and solidifying them.
  • the via-hole conductor b1 passes through the connection portions 18a-b of the dielectric sheet 18a in the z-axis direction.
  • the end of the via-hole conductor b1 on the positive side in the z-axis direction is connected to the external terminal 16a.
  • the end portion on the negative direction side in the z-axis direction of the via-hole conductor b ⁇ b> 1 is connected to the end portion on the negative direction side in the x-axis direction of the signal line 20.
  • the via-hole conductor b2 passes through the connecting portions 18a-c of the dielectric sheet 18a in the z-axis direction.
  • the end of the via-hole conductor b2 on the positive side in the z-axis direction is connected to the external terminal 16b.
  • the end of the via-hole conductor b2 on the negative direction side in the z-axis direction is connected to the end of the signal line 20 on the positive direction side in the x-axis direction.
  • the signal line 20 is connected between the external terminals 16a and 16b.
  • the via-hole conductors b1 and b2 are formed by filling a via-hole formed in the dielectric sheet 18a with a conductive paste mainly composed of silver, tin, copper, or the like and solidifying it.
  • the protective layer 14 is an insulating layer provided on the surface of the dielectric sheet 18a, and covers substantially the entire surface of the dielectric sheet 18a. Thereby, the protective layer 14 covers the ground conductor 22.
  • the protective layer 14 is made of a flexible resin such as a resist material, for example.
  • the protective layer 14 includes a line portion 14a and connecting portions 14b and 14c.
  • the line portion 14a covers the line portion 22a by covering substantially the entire surface of the line portion 18a-a.
  • the connecting portion 14b is connected to the end of the line portion 14a on the negative direction side in the x-axis direction, and covers the surface of the connecting portion 18a-b.
  • openings Ha to Hd are provided in the connection portion 14b.
  • the opening Ha is a rectangular opening provided in the center of the connection portion 14b.
  • the external terminal 16a is exposed to the outside through the opening Ha.
  • the opening Hb is a rectangular opening provided on the positive side in the y-axis direction with respect to the opening Ha.
  • the opening Hc is a rectangular opening provided on the negative direction side in the x-axis direction from the opening Ha.
  • the opening Hd is a rectangular opening provided on the negative side in the y-axis direction with respect to the opening Ha.
  • the terminal portion 22b functions as an external terminal by being exposed to the outside through the openings Hb to Hd.
  • the connecting portion 14c is connected to the end portion on the positive side in the x-axis direction of the line portion 14a and covers the surface of the connecting portion 18a-c.
  • openings He to Hh are provided in the connection portion 14c.
  • the opening He is a rectangular opening provided in the center of the connection portion 14c.
  • the external terminal 16b is exposed to the outside through the opening He.
  • the opening Hf is a rectangular opening provided on the positive direction side in the y-axis direction with respect to the opening He.
  • the opening Hg is a rectangular opening provided closer to the positive direction side in the x-axis direction than the opening He.
  • the opening Hh is a rectangular opening provided on the negative side in the y-axis direction with respect to the opening He.
  • the terminal portion 22c functions as an external terminal by being exposed to the outside through the openings Hf to Hh.
  • the protective layer 14 and the dielectric sheets 18a to 18c are laminated in this order from the positive side in the z-axis direction to the negative side.
  • the material of the protective layer 14 is different from the material of the dielectric sheets 18a to 18c.
  • ground conductors 22 and 24 are provided in the dielectric body 12. Therefore, as shown in FIG. 8, the dielectric element body 12 and the ground conductors 22 and 24 have the center in the z-axis direction of the dielectric element body 12 at the y-axis at the bent positions (the valley line L1 and the mountain line L2). It has an asymmetric structure with respect to a straight line L0 passing in the direction.
  • An asymmetric structure means a structure that is not line symmetric with respect to the straight line L0.
  • the protective layer 14 is made of a material harder than the dielectric sheets 18a to 18c. Accordingly, even if the dielectric element body 12 comes into contact with the battery pack 206, the dielectric element body 12 is not easily worn, so that the ground conductor 22 is protected. Since the dielectric sheet 18c has high elasticity, after the connection with the connectors 100a and 100b, the dielectric sheet 18c is less likely to be chipped when a foreign object collides from the outside, and the ground conductor 24 is protected. As described above, since the main surface on the positive side in the z-axis direction and the main surface on the negative direction side have an asymmetric structure, the desired function can be achieved while maintaining the overall thickness of the dielectric body 12. The high-frequency signal line 10a having the above can be realized.
  • FIG. 9 is an external perspective view of the connector 100b of the high-frequency signal transmission line 10a.
  • FIG. 10 is a sectional structural view of the connector 100b of the high-frequency signal transmission line 10a.
  • the connector 100b includes a connector main body 102, external terminals 104 and 106, a central conductor 108, and an external conductor 110 as shown in FIGS.
  • the connector main body 102 has a shape in which a cylindrical member is connected to a rectangular plate member, and is made of an insulating material such as a resin.
  • the external terminal 104 is provided at a position facing the external terminal 16b on the negative side surface in the z-axis direction of the plate member of the connector main body 102.
  • the external terminal 106 is provided at a position corresponding to the terminal portion 22c exposed through the openings Hf to Hh on the negative surface side in the z-axis direction of the plate member of the connector main body 102.
  • the center conductor 108 is provided at the center of the cylindrical member of the connector main body 102 and is connected to the external terminal 104.
  • the center conductor 108 is a signal terminal for inputting or outputting a high frequency signal.
  • the external conductor 110 is provided on the inner peripheral surface of the cylindrical member of the connector main body 102 and is connected to the external terminal 106.
  • the outer conductor 110 is a ground terminal that is maintained at a ground potential.
  • the connector 100b configured as described above includes the connection portion 12c such that the external terminal 104 is connected to the external terminal 16b and the external terminal 106 is connected to the terminal portion 22c. Mounted on the surface. Thereby, the signal line 20 is electrically connected to the central conductor 108. The ground conductor 22 and the ground conductor 24 are electrically connected to the external conductor 110.
  • FIG. 11 is a plan view of the electronic device 200 using the high-frequency signal transmission line 10a from the y-axis direction.
  • FIG. 12 is a plan view of the electronic device 200 in which the high-frequency signal transmission line 10a is used from the z-axis direction.
  • the electronic device 200 includes a high-frequency signal line 10a, circuit boards 202a and 202b, receptacles 204a and 204b, a battery pack (metal body) 206, and a casing 210.
  • the circuit board 202a is provided with a transmission circuit or a reception circuit including an antenna, for example.
  • a power supply circuit is provided on the circuit board 202b.
  • the battery pack 206 is a lithium ion secondary battery, for example, and has a structure in which the surface is covered with a metal cover.
  • the circuit board 202a, the battery pack 206, and the circuit board 202b are arranged in this order from the negative direction side to the positive direction side in the x-axis direction.
  • the receptacles 204a and 204b are provided on the main surfaces of the circuit boards 202a and 202b on the negative side in the z-axis direction, respectively.
  • Connectors 100a and 100b are connected to receptacles 204a and 204b, respectively.
  • a high frequency signal having a frequency of, for example, 2 GHz transmitted between the circuit boards 202a and 202b is applied to the central conductor 108 of the connectors 100a and 100b via the receptacles 204a and 204b.
  • the external conductor 110 of the connectors 100a and 100b is kept at the ground potential via the circuit boards 202a and 202b and the receptacles 204a and 204b.
  • the high frequency signal transmission line 10a connects between the circuit boards 202a and 202b.
  • the surface of the high-frequency signal line 10a is in contact with the battery pack 206.
  • the high-frequency signal line 10a and the battery pack 206 are fixed with an adhesive or the like. Thereby, a solid ground conductor 22 having no opening exists between the signal line 20 and the battery pack 206.
  • the vicinity of both ends of the high-frequency signal transmission line 10a in the x-axis direction is folded at valley lines L1 and L3, and is folded at mountain lines L2 and L4. As a result, the vicinity of both ends in the x-axis direction of the high-frequency signal transmission line 10 a is bent along the corners of the battery pack 206.
  • the high-frequency signal transmission line 10a has the following structure in order to prevent the signal line 20 from being disconnected and the signal line 20 from being separated from the dielectric sheet 18b during bending.
  • FIG. 13 is a cross-sectional structure diagram along the valley line L1 and the mountain line L2 of the line portion 12a of the high-frequency signal transmission line 10a.
  • the signal line 20 has a neutral surface S ⁇ b> 1 and a dielectric element 12 and the ground conductors 22 and 24 at the bent positions (that is, the valley line L ⁇ b> 1 and the mountain line L ⁇ b> 2). It is provided at a position overlapping in the z-axis direction.
  • the thickness of the protective layer 14, the thickness of the dielectric sheets 18a and 18b, and the thickness of the ground conductors 22 and 24 are set so that the boundary between the dielectric sheet 18a and the dielectric sheet 18b becomes a neutral plane.
  • line 20 is formed on the surface of the dielectric material sheet 18b, and the dielectric body 12 is formed.
  • the signal line 20 is provided at a position where the signal line 20 overlaps the neutral surface S1 of the dielectric element body 12 and the ground conductors 22 and 24 in the z-axis direction at the bent positions (that is, the valley line L1 and the mountain line L2). ing.
  • the position of the neutral plane S1 in the high-frequency signal transmission line 10a can be obtained by Expression (1).
  • the neutral plane S1 in the present embodiment is a neutral plane of the dielectric element body 12 (including the protective layer 14) and the ground conductors 22 and 24 when the signal line 20 is not provided. That is, in the high-frequency signal transmission line 10a, the position of the neutral surface S1 of the dielectric element body 12 and the ground conductors 22 and 24 is calculated without the signal line 20, and overlaps with the neutral surface S1 in the z-axis direction. Thus, the signal line 20 is arranged.
  • the signal line 20 may be disconnected and the signal line 20 may be peeled off from the dielectric sheet 18b at the time of bending illustrated in FIG. It is suppressed.
  • the signal line 20 when the signal line 20 is disconnected, it does not function as a signal line.
  • compressive stress and tensile stress are hardly applied to the signal line 20, it is possible to suppress the signal line 20 from being stretched and contracted, and to suppress fluctuations in the line width and thickness of the signal line 20.
  • fluctuations in the characteristic impedance of the signal line 20 are suppressed. Impedance variation due to variations in the line width and thickness of the signal line 20 leads to an increase in transmission loss in the line portion, but this can be suppressed.
  • dielectric sheets 18a to 18c made of a thermoplastic resin in which a copper foil (metal film) is formed on the entire surface of one main surface are prepared. Specifically, a copper foil is attached to one main surface of the dielectric sheets 18a to 18c. Further, the surface of the copper foil of the dielectric sheets 18a to 18c is smoothed by, for example, applying a zinc plating for rust prevention.
  • the dielectric sheets 18a to 18c are liquid crystal polymers.
  • the thickness of the copper foil is 10 ⁇ m to 20 ⁇ m.
  • the external terminals 16a and 16b and the ground conductor 22 are formed on the surface of the dielectric sheet 18a as shown in FIG. Specifically, a resist having the same shape as the external terminals 16a and 16b and the ground conductor 22 shown in FIG. 7 is printed on the copper foil on the surface of the dielectric sheet 18a. And the copper foil of the part which is not covered with the resist is removed by performing an etching process with respect to copper foil. Thereafter, the resist is removed by spraying a cleaning liquid. Thereby, as shown in FIG. 7, the external terminals 16a and 16b and the ground conductor 22 are formed on the surface of the dielectric sheet 18a by a photolithography process.
  • the signal line 20 is formed on the surface of the dielectric sheet 18b. Further, as shown in FIG. 7, the ground conductor 24 is formed on the surface of the dielectric sheet 18c. Note that the formation process of the signal line 20 and the ground conductor 24 is the same as the formation process of the external terminals 16a and 16b, the signal line 20 and the ground conductor 22, and the description thereof will be omitted.
  • a through hole is formed by irradiating a laser beam to a position where the via hole conductors b1, b2, B1 to B4 of the dielectric sheets 18a and 18b are formed. Then, the through hole is filled with a conductive paste to form via-hole conductors b1, b2, B1 to B4.
  • the dielectric sheets 18a to 18c are laminated and pressure-bonded in this order from the positive direction side in the z-axis direction to the negative direction side so that the signal line 20 and the ground conductor 22 and the ground conductor 24 face each other.
  • a protective layer 14 that covers the ground conductor 22 is formed on the surface of the dielectric sheet 18a by applying a resin (resist) paste by screen printing.
  • the connectors 100a and 100b are mounted on the external terminals 16a and 16b on the connection parts 12b and 12c and the terminal parts 22b and 22c by using solder. Thereby, the high frequency signal transmission line 10a shown in FIG. 1 is obtained.
  • the flexible substrate according to the present invention is not limited to the flexible substrate 10 and the high-frequency signal line 10a, but can be changed within the scope of the gist thereof.
  • the protective layer 14 is formed by screen printing, but may be formed by a photolithography process.
  • the connectors 100a and 100b may not be mounted in the high-frequency signal line 10a. In this case, the end of the high-frequency signal transmission line 10a and the circuit board are connected by solder. Note that the connector 100a may be mounted only on one end of the high-frequency signal transmission line 10a.
  • the connectors 100a and 100b are mounted on the front surface of the high-frequency signal line 10a, but may be mounted on the back surface of the high-frequency signal line 10a. Further, the connector 100a may be mounted on the front surface of the high-frequency signal line 10a, and the connector 100b may be mounted on the back surface of the high-frequency signal line 10a.
  • the high-frequency signal line 10a may be a microstrip line.
  • the signal line 74 is not limited to a signal line through which a high-frequency signal is transmitted, but may be a power line or a ground line.
  • the present invention is useful for a flexible substrate, and is particularly excellent in that it can suppress the disconnection of the linear conductor and the separation of the linear conductor from the dielectric layer.

Landscapes

  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Structure Of Printed Boards (AREA)

Abstract

La présente invention concerne un substrat flexible qui peut empêcher un conducteur linéaire d'être rompu et le conducteur linéaire de se décoller d'une couche diélectrique lorsqu'il est plié. Un ensemble élément diélectrique (12) est un stratifié flexible qui est conçu en stratifiant une couche de protection (14) et des feuilles diélectriques (18a, 18b) et est pliable, et possède une structure asymétrique par rapport à une ligne droite qui passe par le centre dans une direction d'axe z, dans une direction d'axe y, dans une position où l'ensemble élément diélectrique est plié. Une ligne de signal (74) est prévue dans une position qui chevauche le plan neutre (S1) de l'ensemble élément diélectrique (12) dans la direction d'axe z dans la position où l'ensemble élément diélectrique (12) est plié.
PCT/JP2013/078061 2012-10-26 2013-10-16 Substrat flexible WO2014065172A1 (fr)

Applications Claiming Priority (2)

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JP2012236495 2012-10-26
JP2012-236495 2012-10-26

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023276743A1 (fr) * 2021-06-28 2023-01-05 株式会社村田製作所 Substrat multicouche et dispositif électronique

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10134529A (ja) * 1996-10-30 1998-05-22 Fujitsu Ltd 制振シート付きフレキシブル印刷回路及びこれを用いたディスク装置
JPH11204898A (ja) * 1998-01-07 1999-07-30 Nec Niigata Ltd 両面フレキシブル配線基板
JP2003179317A (ja) * 2001-12-10 2003-06-27 Ngk Insulators Ltd フレキシブル配線板

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10134529A (ja) * 1996-10-30 1998-05-22 Fujitsu Ltd 制振シート付きフレキシブル印刷回路及びこれを用いたディスク装置
JPH11204898A (ja) * 1998-01-07 1999-07-30 Nec Niigata Ltd 両面フレキシブル配線基板
JP2003179317A (ja) * 2001-12-10 2003-06-27 Ngk Insulators Ltd フレキシブル配線板

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023276743A1 (fr) * 2021-06-28 2023-01-05 株式会社村田製作所 Substrat multicouche et dispositif électronique
JP7380953B2 (ja) 2021-06-28 2023-11-15 株式会社村田製作所 多層基板及び電子機器

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