JP2013093608A - Printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed wiring board suitable for preventing peeling of a lead terminal layer of a connection terminal part.SOLUTION: A printed wiring board has a connection terminal part T1 inserted and fitted into an external connector. The connection terminal part comprises: a flexible insulating substrate 1 having a tip surface along one outline Y orthogonal to an insertion direction into the external connector; a plurality of lead wiring layers 4 formed on one surface of the insulating substrate; a plurality of strip-like lead terminal layers 2 which have tip surfaces 2a, along the one outline, forming tip parts of the plurality of lead wiring layers respectively to be arranged in parallel to each other and exposed flat external surfaces 2s; and a reinforcing body 7 adhered to the other surface of the insulating substrate at the rear surface position of the lead terminal layer and has a tip surface 7a parallel to the one outline. The tip surface 7a of the reinforcing body is spaced from a tip surface 1a of the insulating substrate 1 on the lead wiring layer side on the basis of the one outline.

Description

  The present invention relates to a printed wiring board, and more particularly to a printed wiring board having a connection terminal portion structure suitable for connection to a connector which is a connection component.

  Recently, with the demands for downsizing, weight reduction, and thickness reduction of electronic devices, similar requirements are increasing for printed wiring boards mounted on electronic devices. Generally, the printed wiring board includes a main body portion provided with a circuit wiring layer for interconnecting various electronic components to be mounted, and a connection terminal portion that is fitted and connected to an external connector.

  The printed wiring board includes various types such as RPC (rigid printed wiring board), FPC (flexible printed wiring board), RPC / FPC board combining these, or FFC (flexible flat cable). . The FFC is a connection-only cable that does not have a circuit wiring layer as described above, but a plurality of lead wiring layers are printed and wired in parallel on a tape-like or ribbon-like flexible insulating substrate. It can be regarded as a type of wiring board.

  On the other hand, the connector is an individual connection part for connecting the connection terminal portion of the printed wiring board to an electronic device or a relay connection cord, etc. With the downsizing and weight reduction of the electronic device and the printed wiring board. The reduction in profile (thinning) has been progressing.

  When the printed wiring board is housed in a device having a movable part such as a hinge such as a foldable mobile phone, at least a part corresponding to the movable part is configured by FPC or FFC. Connection terminals for connectors are often provided along one outline of the FFC.

  By the way, the connection terminal portion of the printed wiring board tends to be thinned with the reduction in the height of the connector. However, even if the insertion and withdrawal of the connector are repeated many times, the mechanical strength and It is required that the shape is maintained and that the contact portion of the connector terminal is securely fitted to maintain a good electrical connection.

  Therefore, a general example of the structure of the connection terminal portion provided on the printed wiring board in the prior art will be described with reference to FIG. FIG. 5 is a schematic cross-sectional view mainly showing the connection terminal portion of the connector and the printed wiring board connected to the connector.

  First, the connector C0 is formed by arranging a plurality of connector terminals C1 made of conductive elastic metal plates formed in a bifurcated manner in a plastic connector case Ca (shown by a broken line), for example, in parallel. Each connector terminal C1 has a contact portion C2 protruding in a convex shape on at least one of the forked inner walls.

  The rectangular flat connecting terminal portion T connected to the main body portion of the printed wiring board PC is formed by patterning a copper foil bonded by an adhesive layer 52 on the upper surface of the rectangular plate-like flexible insulating substrate 51 connected to the main body portion. And a plurality of lead wiring layers 53 each having a parallel pattern.

  Each of the lead wiring layers 53 is covered with a cover lay 55 whose main body is bonded by an adhesive layer 54, and has a lead terminal layer 53a exposed from the cover lay 55 at a tip portion on the connector C0 side. Further, a reinforcing body 57 is bonded to the connecting terminal portion T on the lower surface of the insulating substrate 51 with an adhesive layer 56. And each front end surface of the said insulated substrate 51, the lead terminal layer 53a, and the reinforcement body 57 is aligned with the common front end surface Te along one outline of printed wiring board PC.

  In such a conventional technique, when the connection terminal portion T is inserted and fitted into the connector C0, the distal end surface of the lead terminal layer 53a is in the insertion direction at the position of the common distal end surface Te of the connection terminal portion T. Since the connector terminal C1 is cut at a right angle, the lead terminal layer 53a is likely to be peeled off from the insulating substrate 51 by being caught by the edge portion of the inner wall of the tip of the connector terminal C1 or the convex tip portion of the contact portion C2.

  For this reason, the contact portion C2 of the connector terminal C1 cannot be fitted to the upper surface of the lead terminal layer 53a and a desired electrical connection cannot be made, or the peeled lead terminal layer 53a is pushed and bent to be adjacent to the lead terminal layer 53a. There is a problem that an electrical short circuit occurs between the lead terminal layers in contact with each other. In addition, the repeated insertion and withdrawal operation of the connection terminal portion T to the connector C0 may be performed many times, and it is desirable that the fitting state be continued well over a long period of time. There is a problem that the connection terminal portion T is peeled off very early and the fitting and connection with the connector becomes impossible.

  By the way, since there exists patent document 1 as a prior art regarding peeling of a connection terminal part, this prior art is demonstrated referring FIG. 5 of this application. In the invention of Patent Document 1, when the connection terminal portion T is inserted into the connector C0, the lead terminal layer 53a is inserted while being rubbed against the tapered inner wall surface Cat of the connector case Ca before reaching the connector terminal C1. Thus, it is intended to solve the problem that the lead terminal layer 53a and the insulating substrate 51 are peeled off.

  As a solution to this problem, Patent Document 1 is characterized in that a protrusion P (shown by a two-dot chain line) that protrudes from the tip surface of the lead terminal layer 53a is provided at the tip of the reinforcing body 57 or the insulating substrate 51. Is. However, the invention of Patent Document 1 solves the above-mentioned problems of the prior art due to the phenomenon that the lead terminal layer 53a is peeled off by being caught with the edge part of the inner wall of the tip of the connector terminal C1 or the convex contact part C2. It is not possible.

  For forming the front end surface Te along the outline of the printed wiring board PC, for example, as disclosed in Patent Document 2, a printed wiring board material on which a plurality of identical circuit patterns are formed is provided for each circuit pattern. Conventionally, a technique for cutting out individual printed wiring boards having outlines that form the final outline of the design by punching into a conventional shape has been employed.

Japanese Patent No. 3248266 Japanese Patent No. 2923012

  An object of the present invention is to solve the above-described conventional problems, and in particular, to provide a printed wiring board suitable for preventing peeling of a lead terminal layer of a connection terminal portion.

  The printed wiring board of the present invention has a connection terminal portion that is inserted into and fitted to an external connector, and the connection terminal portion has a flexible end surface that extends along one outline line perpendicular to the insertion direction to the external connector. An insulating substrate, a plurality of lead wiring layers formed on one surface of the insulating substrate, and tip surfaces of the plurality of lead wiring layers that are arranged parallel to each other and that are arranged in parallel to each other And a plurality of strip lead terminal layers having an exposed flat outer surface, and a reinforcing body having a front end surface that is bonded to the other surface of the insulating substrate at the back surface position of the lead terminal layer and is parallel to the one outline. Wherein the front end surface of the reinforcing body is separated from the front end surface of the insulating substrate toward the lead wiring layer with respect to the one outline.

  In the printed wiring board of the present invention, the distance between the one outline and the leading end surface of the lead terminal layer is L1, the distance between the one outline and the leading end surface of the reinforcing body is L2, and the one outline and the final When the distance from the fitting position is L3, the connection terminal portion is formed in a relationship of L1 <L2 ≦ L3.

  The present invention is a printed wiring board having a connection terminal portion to be inserted and fitted into an external connector, and a flexible insulating substrate having a tip surface along one outline line orthogonal to the insertion direction to the external connector; A plurality of lead wiring layers with respect to the first circuit wiring layer formed on one surface of the insulating substrate and respective tip portions corresponding to the connection terminal portions of the plurality of lead wiring layers are configured and arranged in parallel to each other. A plurality of strip lead terminal layers having a front end surface along the one outline and an exposed flat outer surface, and formed on the other surface of the insulating substrate at the back surface of the lead terminal layer and parallel to the one outline. A second circuit wiring layer having a leading end surface and an insulating coating layer covering a surface of the second circuit wiring layer, wherein the leading end surface of the second circuit wiring layer is based on the one outline. Lead wiring from the tip Wherein the spaced apart to the side.

  In the printed wiring board of the present invention, the distance between the one outline and the tip surface of the lead terminal layer is L1, the distance between the one outline and the tip surface of the second circuit wiring layer is L2, and the one outline. The connection terminal portion is formed in a relationship of L1 <L2 ≦ L3, where L3 is a distance between the first fitting position and the final fitting position.

  In the printed wiring board of the present invention, the second circuit wiring layer includes a ground potential layer located on the back surface of the lead terminal layer.

  In the printed wiring board of the present invention, the ground potential layer has a mesh structure.

  According to the printed wiring board of the present invention, the thickness of the distal end portion of the connection terminal portion is thin. Therefore, when the connection terminal portion is inserted into the connector and the tip inner wall of the connector terminal or the tip of the contact portion comes into contact with the tip edge of the lead terminal layer, each tip portion of the insulating substrate and the lead terminal layer becomes a reinforcing body or Since the second terminal is bent toward the second circuit wiring layer, the lead terminal layer is prevented from peeling off.

  Therefore, even if the lead terminal layer is repeatedly inserted into and pulled out from the connector many times, the shape of the lead terminal layer is maintained, and an electrical short circuit between the lead terminal layers is prevented. Good fitting and connection between the part and the connector are ensured reliably and stably.

  In particular, when the second circuit wiring layer includes a ground potential layer located on the back surface of the lead terminal layer, the ground potential layer is connected to the connection terminal portion and the lead wiring layer or lead terminal layer group in the vicinity thereof. For example, impedance control by a microstrip line is possible, and high-speed transmission of circuit input / output signals on a printed wiring board can be improved.

It is a partially cutaway top view which shows the connection terminal part of the printed wiring board which concerns on 1st Embodiment of this invention. It is sectional drawing seen in the arrow direction along the AA line of FIG. 1, and the schematic sectional drawing of a connector terminal is shown collectively. It is sectional drawing for demonstrating the fitting state of the connection terminal part and connector terminal of the printed wiring board which concern on 1st Embodiment of this invention. It is sectional drawing equivalent to the AA line of FIG. 1 which shows the connection terminal part of the printed wiring board which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows an example of the connecting terminal part of the printed wiring board of a prior art.

  Hereinafter, the printed wiring boards according to the first and second embodiments of the present invention will be sequentially described with reference to FIGS. Here, the same reference numerals given throughout FIGS. 1 to 4 indicate the same parts, and the detailed description of the same parts is omitted in the subsequent drawings.

[First Embodiment]
The connection terminal portion of the printed wiring board according to the first embodiment is mainly shown in FIGS. First, the relationship between the connection terminal portion and the external connector will be described with reference to FIG. 1 (partially cutaway plan view) and FIG. 2 (cross-sectional view taken along line AA in FIG. 1).

  The printed wiring board PC is a connection terminal that is electrically connected by being inserted into and fitted to a main body portion on which a circuit wiring layer (not shown) for interconnecting various electronic components to be mounted and an external connector C0 is formed. It has a part T1.

  The connector C0 includes a plurality of connector terminals C1 made of, for example, a conductive elastic metal plate having a bifurcated leg portions C1a and C1b and formed in, for example, a U-shape, a connector case made of plastic (reference: FIG. 5). Ca) are arranged in a parallel relationship. Further, a contact portion C2 protruding in a chevron shape (convex shape) is formed on the inner wall on the tip end side of the one leg portion C1a, and the tip end portion of the one leg portion C1a is formed on one angled surface of the contact portion C2. The shape is an acute angle having an extended taper C2t, and the other leg C1b is longer than the leg C1a. The connection terminal portion T1 has a terminal length corresponding to the U-shaped depth length of the connector terminal C1, and is fitted and connected to the inner wall of the connector terminal C1 and the contact portion C2.

  The connection terminal portion T1 includes an insulating substrate 1 having a distal end surface 1a along one outline Y (see FIG. 1) perpendicular to the insertion direction (arrow X) into the connector C0, and one surface of the insulating substrate 1 (see FIG. 2 has a plurality of lead terminal layers 2 formed in an arrangement parallel to each other. Each lead terminal layer 2 has a tip surface 2a parallel to the one outline Y, and constitutes tip portions of a plurality of lead wiring layers 4 electrically connected to the circuit wiring layer (not shown). It is an extended pattern. The terminal layer 2 and the wiring layer 4 are both bonded to the upper surface of the insulating substrate 1 with the adhesive layer 3.

  An insulating coating layer 6 is adhered to the surface of the circuit wiring layer and the lead wiring layer 4 with an adhesive layer 5, and the insulating coating layer 6 has a terminal length corresponding to the U-shaped depth length of the connector terminal C1. It is formed so that the upper surface of each lead terminal layer 2 is exposed. The front end surface 6 a of the insulating coating layer 6 is spaced apart from the front end surface 2 a of the lead terminal layer 2 by the length of the terminal parallel to the one outline Y, and the position of the front end surface 6 a is the root of the lead terminal layer 2. And the lead wiring layer 4.

  Each lead terminal layer 2 is formed as a long rectangular flat strip having a flat outer surface 2s on the upper surface of the fitting region with the contact portion C2 of the connector terminal C1, and the length direction of the lead terminal layer 2 is the one outer shape. They are arranged in parallel at a predetermined interval (pitch) so as to be orthogonal to the line Y. Each lead terminal layer 2 is formed on one surface of the insulating substrate 1 so as to have a distance L1 between the front end surface 2a and the one outline Y.

  Here, the interval L1 is illustrated such that the front end surface 2a is separated toward the lead wiring layer 4 with the one outline Y as a reference. The distance L1 may include L1 = 0. In this case, the leading end surface 2a of the lead terminal layer 2 is formed so as to coincide with the one outline Y together with the leading end surface 1a of the insulating substrate 1. Further, although not shown in the drawing, the exposed upper surface of each lead terminal layer 2 is entirely made of nickel or the like in order to prevent corrosion or reduce contact resistance with the connector terminal C1. A plating layer made of a highly conductive metal layer such as gold or a solder layer is formed.

  On the other surface (the lower surface in the figure) of the insulating substrate 1, a reinforcing body 7 is bonded to the back surface position in order to reinforce the mechanical strength from the back surface side over the entire array of the lead terminal layers 2. Bonded by layer 8. The reinforcing body 7 has a front end surface 7 a parallel to the one outer shape line Y and a flat outer surface 7 s exposed to the outside, and the front end surface 7 a is a front end of the insulating substrate 1 with respect to the one outer shape line Y. It is formed so as to be separated from the surface 1a toward the lead wiring layer 4 side.

  FIG. 2 shows a distance L2 between the front end surface 7a of the reinforcing body 7 and the one outline Y, and the final contact portion C2 of the connector terminal C1 with respect to the flat outer surface 2s of the lead terminal layer 2 is shown. A distance L3 between the target fitting position and the one outline Y is shown.

  The reinforcing body 7 has an end face 7b opposite to the tip face 7a, and terminates at a position where a part of the reinforcing body 7 overlaps the insulating coating layer 6 beyond the root of the lead terminal layer 2. ing. The end position of the opposite end surface 7b is set according to the degree of demand for the reinforcement. The reinforcing body 7 can be formed using a reinforcing film or a reinforcing plate made of an insulating material such as polyimide resin or glass epoxy resin.

  Next, specific examples of materials and shape dimensions of each member constituting the connection terminal portion T1 will be described. For example, using a single-sided copper-clad substrate material (single-sided CCL) in which a 35 μm-thick copper foil is bonded to one side of a flexible insulating substrate 1 made of a polyimide resin film having a thickness of 25 μm, the copper foil is subjected to circuit patterning to form a circuit. A wiring layer, a lead wiring layer 4 and a lead terminal layer 2 are formed. An epoxy thermosetting resin adhesive having a thickness of 10 μm is used for the adhesive layer 3 at this time. In addition, a liquid crystal polymer or the like can be used as the base material of the flexible insulating substrate 1.

  The insulating covering layer 6 is made of, for example, a cover lay made of a polyimide resin film having a thickness of 25 μm, and the reinforcing body 7 is made of, for example, a film-like or flat plate-like polyimide resin having a thickness of 125 μm. Reference numeral 5 denotes a thickness of 35 μm, and the adhesive layer 8 has a thickness of 50 μm. In both cases, an epoxy thermosetting resin adhesive is used.

  Therefore, in this case, the connection terminal portion T1 has a thickness t1≈245 μm between the flat outer surface 2s (upper surface) of the lead terminal portion 4 and the flat outer surface 7s (lower surface) of the reinforcing member 7, and the lead terminal layer 2 A thickness t2≈70 μm is provided between the flat outer surface 2s (upper surface) and the exposed surface 1s of the other surface of the insulating substrate 1.

  The number (number of terminal pins) of the plurality of lead terminal layers 2 is set in accordance with, for example, various connector pin numbers ranging from 4 to 50. Here, the terminal length, terminal width, and terminal pitch are as follows. Are formed in an array pattern of 1.7 mm, 0.3 mm, and 0.5 mm, respectively.

  In addition, the lead width and lead pitch of each lead wiring layer 4 have the same dimensions as the terminal width and terminal pitch, respectively, and the distances L1 to L3 have a relationship of L1 <L2 ≦ L3. The pattern shape of the plurality of lead terminal layers 2 can take various forms such as a parallel pattern and a staggered pattern.

  Next, with reference to FIG. 3, the fitting state in the insertion operation to the connector terminal C1 of the said connecting terminal part T1 is demonstrated. FIG. 3A shows an initial stage of insertion in which the front end surface of the connection terminal portion T1 is inserted into the connector terminal C1 slightly beyond the front end of the contact portion C2 of the connector terminal C1. In FIG. 3B, the insertion of the front end surface of the connection terminal portion T1 is advanced, and the front end of the contact portion C2 of the connector is fitted and contacted with the flat outer surface 2s of the lead terminal layer 2 at the final fitting position. The stage where the electrical connection is completed is shown.

  By the way, as a kind of connector, there are a fixed type in which the distance between the two forks of the connector terminal C1 is constant, and an open / closed type in which the distance between the two forks can be manually adjusted. Here, an embodiment using the fixed connector as an example will be described. The connector terminal C1 is finally elastically fitted to the flat outer surface 2s of the lead terminal layer 2 with an appropriate pressure. The distance D1 between the tip of the contact portion C2 on the inner wall of the one leg C1a and the inner wall of the other leg C1b is smaller than the maximum thickness t1 of the connection terminal portion T1, and the size is larger or smaller. The relationship is t2 <D1 <t1.

  Since the insulating substrate 1 has flexibility, the connection terminal portion T1 has a certain degree of flexibility as a whole. However, due to such a thickness relationship, the connection terminal portion T1 has a thin wall thickness t2 smaller than the thickness t1. Since the bending rigidity of the front end portion of the connecting terminal portion T1 is smaller than the portion where the reinforcing body 7 is present, the front end portion of the connection terminal portion T1 is easily bent with respect to bending stress from the outside.

  Therefore, as shown in FIG. 3A, the flat outer surface 7s (lower surface) of the reinforcing body 7 of the connection terminal portion T1 is placed along the inner wall of the lower leg portion C1b of the connector terminal C1 to connect the connection terminal portion. When T1 is inserted into the connector terminal C1, at the initial stage of insertion, the tip of the contact portion C2 contacts the tip of the lead terminal layer 2 through the taper C2t of the tip of the leg portion C1a of the connector terminal. The tip is bent toward the reinforcing body 7 in the thickness direction.

  Due to the bending of the leading end portion, the leading end portion of the lead terminal layer 2 does not get caught by the connector terminal contact portion C2, and the mutual fitting proceeds while being pressed against the insulating substrate 1 side. Is prevented from peeling off. Thereafter, the tip of the contact portion C2 slides on the surface of the flat outer surface 2s of the lead terminal layer 2, and is fitted and electrically connected at a normal position in the connector standard as shown in FIG. Complete the connection. At this stage, the tip of the connection terminal portion T1 is restored to a flat state.

  As a result, the shape of the lead terminal layer 2 is maintained over a long period of time even if the insertion and extraction repeated operations into the connector C0 are repeated many times, and the lead terminal layer 2 is connected between the lead terminal layers 2. Thus, a good fitting and connection state between the connection terminal portion T1 and the connector C0 is ensured reliably and stably.

  In addition, since the leading end surface 2a of the lead terminal layer 2 is spaced apart from the leading end surface 1a of the insulating substrate 1 in the direction away from the one outline Y with an interval L1, in the initial stage of inserting the connecting terminal portion into the connector. The taper C2t at the tip end of the connector terminal C1 and the inclined contact of the contact portion C2 with the tip end edge of the lead terminal layer 2 become smooth, and the lead terminal layer can be further prevented from peeling off.

  By the way, each said printed wiring board PC which has the said connection terminal part T1 forms several identical circuit patterns in the wiring base material which consists of one single-sided copper clad laminated board (single-sided CCL), and uses a punching die. It is cut out into a shape having a predetermined outline by punching (cutting) each circuit pattern.

  When the surface of the lead terminal layer 2 is plated with nickel, gold or the like, a feeding electrode (not shown) for plating is provided on the outer side of one outline Y (see FIG. 1) of the wiring substrate of the printed wiring board PC. The plating lead portion for connecting the power supply electrode and the tip end portion of each lead terminal layer 2 is patterned in advance, and after plating, the intermediate portion of the plating lead portion is punched to form the one outline Y May be divided to match. In this case, since the remaining plated lead portion constitutes the tip end portion of the lead terminal layer 2, the lead terminal layer 2 has a relationship of the interval L1 = 0, and the outer shape of the printed wiring board PC is punched out. It can be easily formed simultaneously with molding.

  Here, the wiring base material is a three-layer material CCL made of copper foil / adhesive / base film. For example, a surface of an insulating substrate made of a polyimide resin film is sputter-plated, for example. By using a two-layer material CCL made of a copper / base film on which a copper layer is formed, it is possible to further adapt the connector to a low profile.

  As described above, according to the printed wiring board of the first embodiment, the lead terminal layer is prevented from being peeled off when the connection terminal portion is fitted and connected to the external connector, and insertion / extraction into the connector is performed many times. Even if it extends, the shape of the lead terminal layer is maintained for a long period of time, electrical short-circuit between the lead terminal layers is prevented, and the fitting and connection state is ensured reliably and stably.

[Second Embodiment]
Next, a printed wiring board according to a second embodiment of the present invention will be described with reference to FIG. The printed wiring board PCa in the present embodiment shows an example in which circuit wiring layers are provided on both surfaces of the main body, and is formed using a double-sided copper-clad laminate (double-sided CCL). A first circuit wiring layer (not shown), a lead terminal layer 2, adhesive layers 3 and 5, a lead wiring layer 4 and a first insulating coating layer 6 provided on one surface of the insulating substrate 1 The same reference numerals as those shown in the embodiment are the same or similar.

  A second circuit wiring layer 21 is bonded to the other surface (lower surface) of the insulating substrate 1 by an adhesive layer 22, and the second circuit wiring layer 21 faces the back surface position of the lead terminal layer. The front end surface 21a extends and is parallel to the one outline Y (see FIG. 1), and the front end surface 21a is formed away from the front end surface 1a of the insulating substrate toward the lead wiring layer. In addition, the portion of the second circuit wiring layer 21 that extends opposite the back surface of the lead terminal layer is formed by a circuit pattern including a ground potential layer and connected to the ground potential (GND).

  The second circuit wiring layer 21 forms a step with respect to the other surface of the insulating substrate 1 at the front end portion adjacent to the front end surface 1a of the insulating substrate 1 with the front end surface 21a as a boundary. The thickness corresponds to the thickness and dimension of the second circuit wiring layer 21.

  A second insulating coating layer 23 is bonded to the surface of the second circuit wiring layer 21 and the lower surface of the insulating substrate 1 with an adhesive layer 24. The second insulating coating layer 23 is formed of, for example, a polyimide resin film. It consists of a coverlay made of metal and is formed along the step surface. Accordingly, the thickness t2 of the distal end portion of the connection terminal portion T2 sandwiched between the outer surface 23s2 of the second insulating coating layer 23 that does not overlap the second circuit wiring layer 21 and the flat outer surface 2s is set to the second thickness t2. The insulating coating layer 23 is formed to be smaller than the thickness t1 of the connection terminal portion T2 between the outer surface 23s1 of the portion overlapping the second circuit wiring layer 21 and the flat outer surface 2s of the lead terminal layer 2.

  Here, a specific example of the thickness of each part is shown. The insulating substrate 1 is 25 μm, the adhesive layers 3 and 22 are each 10 μm, the double-sided CCL copper foils are 35 μm, the first and second insulating coating layers 6. , 23 are each 25 μm, and the insulating coating layers 5 and 24 are each 35 μm. Accordingly, the thickness t1 of the connection terminal portion T2 is 185 μm, whereas the thickness t2 of the tip end portion of the connection terminal portion T2 is thinned to 150 μm.

  Of course, for example, the second insulating coating layer 23 may cover the tip surface 21a of the second circuit wiring layer 21 but not overlap the tip portion of the insulating substrate 1. Since the thickness t2 of the tip portion can be further reduced by the thickness of the adhesive layers 22 (10 μm) 10 and 24 (35 μm), the thickness t2 can also be reduced to 115 μm.

  In addition, with respect to the distance between the connection terminal portions T2 in the terminal length direction, the distance between the one outline Y (see FIG. 1) and the tip end surface 2a of the lead terminal layer 2 is L1, and the one outline Y When the distance between the second circuit wiring layer 21 and the front end surface 21a is L2, and the distance between the one outline Y and the final fitting position is L3, L1 <L2 ≦ L3. Yes.

  The relationship of L2 ≦ L3 will be described. The final fitting position between the lead terminal layer 2 and the connector contact portion C2 is the same as that of the connection terminal portion T1 (T2) in both the first and second embodiments. Although it is located on the root side, the relationship of L2 = L3 is included because it can be adjusted to the position of the tip surface 7a of the reinforcing body 7 or the tip surface 21a of the second circuit wiring layer 21.

  According to the printed wiring board PCa of the second embodiment, it is possible to achieve more multifunctional circuits than that of the first embodiment, and in particular, the second circuit wiring layer 21 is positioned on the back surface of the lead terminal layer. When the ground potential layer is used, the ground potential layer enables impedance control by a microstrip line for the connection terminal portion and the lead wiring layer and the lead terminal layer group in the vicinity thereof, and the circuit on the printed wiring board. High-speed transmission of input / output signals can be improved. The ground potential layer of the second circuit wiring layer 21 can have a mesh structure. In this case, the area of the ground potential layer can be easily adjusted by adjusting the mesh density, and the impedance can be easily controlled. For example, if the mesh network is made fine and dense, the surface area of the ground potential layer can be increased to increase the impedance.

  Further, when compared with that of the first embodiment, the second circuit wiring layer 21 supports the lead terminal layer 2 from the back side together with the insulating coating layer 23 covering the surface thereof. It can also function as a reinforcement. Of course, when it is desired to further enhance the degree of reinforcement of the connection terminal portion T2, a reinforcing plate (7) as shown in the first embodiment may be provided on the flat outer surface 23s1 of the second insulating coating layer 23. it can.

  In this case, if the installation of the reinforcing plate is avoided from the flat outer surface 23s2 located at the distal end portion of the second insulating coating layer 23, the thickness t2 on the distal end side of the connection terminal portion T2 is the thickness on the root side. Since the thickness is further reduced as compared with the length t1, the difference in bending rigidity between the distal end side and the root side of the connection terminal portion T2 is increased. Therefore, at the time of the connector insertion operation, the tip end portion of the connection terminal portion T2 is more easily bent, so that the prevention of the peeling of the lead terminal layer 2 can be further ensured. Further, in each of the above embodiments, the lead terminal layer 2 can be more reliably prevented from peeling off by chamfering the leading edge where the flat outer surface 2s and the leading end surface 2a of the lead terminal layer 2 intersect.

  By the way, the present invention is not limited to the forms of the printed wiring boards PC and PCa of the first and second embodiments, but the multilayer printed wiring board in which the main body of the printed wiring board is formed by laminating a plurality of wiring base materials, The present invention can also be applied to an FFC that is a printed wiring board that does not have a circuit wiring layer that interconnects electronic components to be mounted. Further, the present invention can be widely applied to any type of printed wiring board of FPC, RPC, or FPC / RPC combination that has a connection terminal portion for connector fitting connection.

DESCRIPTION OF SYMBOLS 1 Insulating substrate 1a Front end surface 2 of insulating substrate Lead terminal layer 2a Front end surface 2s of lead terminal layer Flat outer surfaces 3, 5, 8, 22, 24 of lead terminal layer Adhesive layer 4 Lead wiring layers 6, 23 Insulating coating layer 6a, 23a Front end surface 6s, 23s1, 23s2 of each insulating coating layer Flat outer surface 7 of each insulating coating layer Reinforcing body 7a Front end surface 7s of reinforcing body Flat outer surface 21 of reinforcing body Circuit wiring layer 21a Front end surface C0 of circuit wiring layer Connector C1 Connector Terminal C1a, C1b Connector terminal leg C2 Connector terminal contact C2t Taper PC, PCa Printed wiring board T1, T2 Connection terminal X Insertion direction Y Outline of printed wiring board

Claims (4)

  A printed wiring board having a connection terminal portion to be inserted and fitted into an external connector, a flexible insulating board having a front end surface along one outline perpendicular to the insertion direction to the external connector, and the insulating board The plurality of lead wiring layers for the first circuit wiring layer formed on one surface and the tip portions corresponding to the connection terminal portions of the plurality of lead wiring layers are arranged in parallel with each other and the one outline A plurality of strip lead terminal layers having a front end surface along the exposed flat outer surface and a front end surface formed on the other surface of the insulating substrate at a back position of the lead terminal layer and parallel to the one outline. A second circuit wiring layer having an insulating coating layer covering a surface of the second circuit wiring layer, and a front end surface of the second circuit wiring layer is formed from a front end surface of the insulating substrate with respect to the one outline. Separated to the lead wiring layer side Printed circuit board, characterized by that.   The distance between the one outline and the leading end surface of the lead terminal layer is L1, the distance between the one outline and the leading end surface of the second circuit wiring layer is L2, and the distance between the one outline and the final fitting position. 2. The printed wiring board according to claim 1, wherein the connection terminal portion is formed in a relationship of L1 <L2 ≦ L3, where L3 is L3.   3. The printed wiring board according to claim 1, wherein the second circuit wiring layer includes a ground potential layer located on a back surface of the lead terminal layer. 4.   The printed wiring board according to claim 3, wherein the ground potential layer has a mesh structure.

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