JP2010287606A - Flexible printed wiring board, and connector structure integrated with flexible printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible printed wiring board capable of achieving both fine pitches as well as high density of wiring and connection parts by improving connection density and simplification as well as cost reduction of a connecting structure. <P>SOLUTION: In this flexible printed wiring board 10, a wiring pattern 5 is formed on the surface of an insulating base material 1. In this case, contact bumps 3 linking with the wiring pattern 5 and making contact with a connection pad 22 formed on the surface of the printed wiring board 20 of a connection counterpart by being pressed against it to make electrical connection with the connection pad 22 are provided on the surface of the insulating base material 1, and an elastic body sheet 9 is provided on the back side thereof. The contact bump 3 itself directly functions as a connector member for reliable electrical connection with the connection pad 22 of the printed wiring board 20 of the connection counterpart by a load applied through the elastic body sheet 9. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a flexible printed wiring board and a flexible printed wiring board integrated connector structure set so as to be electrically connected to, for example, a rigid printed wiring board of a connection counterpart.

As electronic devices become faster and more dense, not only printed circuit boards for motherboards used in them, but also flexible printed circuit boards used as transmission lines that connect module wiring boards to each other, have a large capacity signal. Realization of improvements in transmission characteristics, high frequency characteristics, and the like has been demanded.
In order to improve the data transfer performance of flexible printed wiring boards, it is extremely important to increase the number of pins and the number of layers. More signal wiring, ground wiring, power supply wiring, etc. are placed in a limited area. Must. In order to respond to such technical demands, technological development relating to so-called fine pitches such as wiring patterns has been actively conducted mainly for shortening the distance between wirings and miniaturizing the wiring width and wiring pitch. .
A connector is an important part for reliably transmitting signals through these transmission lines. The performance required for a connector is generally that it is possible to connect / disconnect one or a plurality of wires (in other words, the connection / disconnection of a pair of connectors) reliably, quickly, and simply, That is, it is possible to keep the connection state stable over a long period of time and to ensure the reliability of data transmission.

  As a connector used for such an application, there is an in-line type connector in which contact terminals respectively connected to each of a plurality of contact terminals provided on a mating connector are arranged in a straight line. The in-line type connector is generally attached to the flexible printed wiring board at an external connection terminal connected to each contact terminal on the connector side and a wiring terminal on the flexible printed wiring board side. This is performed by aligning the external connection terminals and joining (fixing) both terminals by mechanical engagement or soldering.

  On the other hand, as a suitable connector when it is required to provide a large number of contact terminals in a limited area, an area in which contact terminals and external connection terminals connected to the contact terminals are arranged two-dimensionally (in a matrix). Type connectors have been proposed. In the case of an in-line type connector, a large number of contact terminals are arranged in a line, which occupies a long area, whereas in an area type connector, the contact terminals are arranged in a matrix. Therefore, the area occupied by the contact terminal has a two-dimensional expanse, and although the area as the area is required, the outer dimensions can be accommodated in a smaller size than the in-line type. There is.

The area type connector makes electrical connection on the flexible printed wiring board and the other side, for example, the rigid printed wiring board, by sliding and contacting each other at the same pitch. Is provided with a contact piece and a contact terminal having a buffer structure such as a microspring, and after being connected to each other, it is electrically fixed (fixed) with, for example, a fixing screw. A structure having a connection state is generally used (Patent Document 1).
Alternatively, instead of using a contact piece or contact terminal having a buffer structure such as a micro spring, a solder bump made of a material such as a low melting point solder is used, and the connection pads between both wiring boards are soldered by the solder bump. A technique for fixing the connection state has also been proposed (Patent Document 2).
As connectors for flexible printed wiring boards, in-line connectors are most often used because of their simple structure, good use in the field of electronic components, and relatively low manufacturing costs. ing.

JP 2008-91712 A JP-A-8-116145

However, the flexible printed wiring board using the conventional connector as described above has the following problems.
The most serious problem in the fine pitch technology for the wiring circuit system is, for example, the main components of the transmission line system connected to the main body wiring circuit system provided on the rigid printed wiring board of the secular partner It is the connection density of the flexible printed wiring board which is and the connector connected to it.

  In the case of inline type connectors, the external connection terminals and wiring patterns on the flexible printed wiring board side formed by the photofabrication process are relatively easy to make fine pitches. The external connection terminal on the connector side, which requires three-dimensional processing, tends to be difficult to cope with fine pitch. For this reason, the design requirement to stop the area where the connector is installed in a limited area and the functional requirement as an electric circuit system to dispose a necessary number of wires therewith compete. As a result, the pitch of the external connection terminals that is regulated by the processing accuracy on the connector side restricts the arrangement pitch of the contact terminals, that is, the connection density of the connector. The arrangement pitch is about 0.3 mm is the minimum. Because of these factors, inline connectors are generally used for flexible printed wiring boards used in electronic devices that are strongly required to be connected to transmission lines with a large number of terminals and to be miniaturized and thinned for cellular phones and the like. Has the problem of being extremely disadvantageous.

  In the case of an area type connector, since the connection terminals can be arranged two-dimensionally, it is relatively easy to increase the number of pins. However, on the other hand, the structure such as a microspring structure and the manufacturing process for forming the structure are extremely complicated. There is a problem that it tends to be. As a result, there is a problem that the manufacturing cost of the area-type connector is likely to increase. This is considered to be one of the reasons why the area-type connector has not yet spread to the in-line connector.

  Further, in the case of using a solder bump instead of the microspring structure, there is a problem that it is difficult to make a fine pitch of 0.5 mm or less due to the restriction of the molding process accuracy of the solder bump. In addition, there is a problem that the manufacturing cost tends to increase. In addition, since the electrical connection state is fixed (fixed) by soldering using solder bumps, there is a problem that it is practically impossible to attach and detach again after being connected once.

Here, regardless of the distinction between the in-line type and the area type, the following mechanical and electrical characteristics that are particularly strongly required for the connector are as follows.
(1) A constant load applied to the contact can be permanently maintained.
(2) Ensuring the spring back property when contacting the contact electrode with the counterpart electrode.
(3) Equalizing the load on each contact formed in a plurality.
(4) Maintaining contact connection performance and shape reproducibility when insertion / extraction (removal) is repeated.
In order to satisfy these required characteristics, various contact pieces and contact terminals having a buffer structure such as a microspring as described in the description of the background art have been proposed. There is a problem that the contact structure becomes complicated, and there is a problem that the manufacturing process and the material cost tend to be expensive due to the complicated manufacturing process.
In addition, the complexity of the contact structure is a limitation, and it is easy to limit the further miniaturization of the pitch between the contacts. As a result, the contacts that can be formed in a limited area are limited. There is a problem that the number tends to be increased, that is, it is difficult or impossible to further improve the electrical connection density (contact formation density).

In this way, with conventional connectors, regardless of whether the inline type or area type connector is used, the flexible printed wiring board or the other party's rigid printed wiring board connected to the flexible printed wiring board must be a separate component. It is necessary to attach a connector or another component such as a microspring structure with high precision, for example, by surface mounting, in response to the fine pitch. At least the procurement cost and manufacturing cost of the connector itself, which is another component, is required. There was a problem that would increase. In addition, there is a problem in that the labor and process for attaching the connector or the like to the flexible printed wiring board increase the cost.
In addition, due to restrictions due to processing accuracy on the structure of the connector, the improvement in electrical connection density is hindered, and as a result, the connection portion of the flexible printed wiring board and the wiring pattern connected to it are made finer. There was a problem of being obstructed.

  The present invention has been made in view of such problems, and its purpose is to increase the fine pitch and density of wiring and connection parts by improving the connection density, and to simplify and reduce the cost of the connection structure. An object of the present invention is to provide a flexible printed wiring board and a flexible printed wiring board integrated connector structure that can achieve both of them.

The flexible printed wiring board of the present invention is a flexible printed wiring board in which a wiring pattern is formed on the surface of an insulating base material, and is connected to the wiring pattern on one side of the insulating base material and connected. By being pressed against and contacted with the connection pads arranged on the surface of the counterpart wiring board, the electrical connection with the connection pads is directly arranged and formed, Protruding contact bumps that function as connector members for electrical connection with the connection pads of the wiring board on the other end of the connection, and one side of the insulating substrate opposite to the one side on which the contact bumps are arranged An elastic sheet provided on the surface is provided.
In addition, the flexible printed wiring board integrated connector structure of the present invention has a wiring pattern formed on one side of an insulating substrate, and is connected to the wiring pattern and arranged on the surface of the wiring board of the connection partner. An arrangement is made so as to directly make electrical connection with the connection pad by being pressed against and contacted with the connection pad, and the connection pad of the wiring board of the other end of the connection, A flexible printed wiring board having a protruding contact bump functioning as a connector member for electrical connection, and a surface on the opposite side of the insulating substrate on which the contact bump is arranged. On the wiring board of the other end of the connection so that the contact bump is connected to the connection pad on the wiring board of the other end of the connection and the elastic sheet thus connected. A flexible printed wiring board is disposed facing each other, and on the flexible printed wiring board, the elastic sheet is overlaid on an area corresponding to at least the area where the contact bumps are arranged and formed on the elastic sheet. The flexible printed wiring board is placed face to face on the connection partner wiring board so that the contact bumps are connected to the inner layer upper board to be connected to the connection pads in the connection counterpart wiring board, And at least the connection pad under the wiring board of the other end of the connection in a state where the elastic sheet is superimposed on at least the area corresponding to the area where the contact bumps are arranged and formed on the flexible printed wiring board Are disposed in a region corresponding to the region where the array is formed, and the inner layer upper plate or It is provided to penetrate one of the inner layer lower plates, the elastic sheet, the flexible printed wiring board, and the connection counterpart wiring board, and used to align them as a whole. And an alignment pin that is provided upright on the surface of the inner layer upper plate or the inner layer lower plate that is not provided with the alignment hole and that can be inserted into the alignment hole. The connection partner is connected so that the contact bump in the flexible printed circuit board is connected to the connection pad in the connection circuit board by inserting the alignment pin through the alignment hole and aligning the alignment pin. The flexible printed wiring board is placed facing the other printed wiring board and the flexible printed wiring In a state where the elastic sheet is superposed on the wire board, the elastic sheet, the flexible printed wiring board, and the wiring board to be connected are sandwiched between the inner layer upper board and the inner layer lower board. It is characterized by doing so.

According to the present invention, on one side of the insulating base material, it is connected to the wiring pattern by being pressed against and contacted with the connection pads arranged on the surface of the wiring board of the connection partner. Protruding contact bumps that are arranged so as to directly make electrical connection with the pads themselves and function as connector members for electrical connection with the connection pads of the wiring board of the other party of the connection Since the elastic sheet is provided on the side opposite to the one side where the contact bumps in the insulating substrate are arranged, the connector is attached separately from the flexible printed wiring board. Contact bumps provided directly on the flexible printed wiring board and connection pads provided directly on the other wiring board without using any connecting parts. Even if there is a non-negligible variation in the height of the contact bumps, the electrical connection between these two wiring boards can be taken directly, and the variation is mainly Absorption and relaxation can be ensured by the elasticity of the elastic sheet and the flexibility of the insulating substrate. As a result, there is no need for connecting parts that are likely to be complicated and have high costs, such as separately attached connectors and microsprings. It is possible to achieve both a fine pitch and a high density, and a simplified connection structure and a low cost.
Further, in particular, the flexible printed wiring board faces the connection counterpart wiring board so that the contact bumps of the flexible printed wiring board of the present invention are connected to the connection pads on the above-mentioned connection counterpart wiring board. Place the elastic sheet on the flexible printed wiring board and place the elastic sheet, the flexible printed wiring board and the other wiring board to be connected between the inner layer upper board and the inner layer lower board. By adopting a flexible printed wiring board integrated connector structure that is sandwiched and held between the contact bumps and the connection pads, the electrical connection state between the contact bumps and the connection pads can be more reliably and permanently held. .

It is a figure which shows the structure of the principal part of the flexible printed wiring board integrated connector structure which concerns on embodiment of this invention which uses the flexible printed wiring board which concerns on embodiment of this invention. It is a figure which shows the structure of the principal part of the flexible printed wiring board which concerns on embodiment of this invention. FIG. 3 is a diagram showing an extracted portion where contact bumps are arranged in the flexible printed wiring board shown in FIG. 2. It is a figure which shows typically the condition which arrange | positions both wiring boards just before connecting the contact bump of the flexible printed wiring board shown in FIG. 2 to the connection pad of the rigid printed wiring board of the other party of a connection. FIG. 5A is a cross-sectional view (FIG. 5A) showing an enlarged and enlarged view of one contact bump and the structure in the vicinity thereof in the flexible printed wiring board shown in FIG. 2, and the other printed wiring board connected thereto. It is a figure (FIG.5 (b)) which extracts and expands and shows the structure of a connection pad and its vicinity. The flexible printed wiring board according to the embodiment of the present invention and the printed wiring board (the other party) of the connection immediately before the contact bump and the connection pad according to the embodiment of the present invention are pressed and connected. FIG. 10 is a diagram showing a distance L between adjacent contact bumps and a height variation Δh between the contact bumps in a state where the inner layer upper plate and the inner layer lower plate are sandwiched and arranged facing each other. It is a figure which shows typically the state which the connection defect generate | occur | produced without absorbing the variation in the height of a contact bump. It is a figure which shows typically the state which ensured the reliable connection by absorbing the variation in the height of a contact bump. It is a figure which shows typically the case where the dispersion | variation P has arisen in the thickness of the insulating base material, and the dispersion | variation S has arisen in the height of the contact bump.

  Hereinafter, a flexible printed wiring board according to an embodiment of the present invention, and a flexible printed wiring board integrated connector structure using contact bumps formed on one side thereof as a part of the main components of the connector structure, This will be described with reference to the drawings.

As shown in FIG. 1, the flexible printed wiring board integrated connector structure according to the embodiment of the present invention is opposite to the one side formed by arranging the cover layer 2 and the contact bump 3 in the insulating base material 1. A flexible printed wiring board 10 having an elastic sheet 9 attached to a side surface (hereinafter, also referred to as a back surface for convenience), an inner layer upper plate 11, an inner layer lower plate 12, and an alignment pin 13. , The alignment hole 14, the external printed circuit board 20, the outer layer upper board 31, the outer layer lower board 32, and the fixing board. A bolt 33, a nut 34, and a spring 35 are provided as main parts.
The flexible printed wiring board 10 according to the embodiment of the present invention, which is incorporated and used as one of the main components in such a flexible printed wiring board integrated connector structure, is as shown in FIG. Insulating substrate 1, cover layer 2, contact bump 3, fixing bolt hole 4, wiring pattern 5, conductor pad 6, body wiring region 7, opening 8, and elastic sheet 9 The alignment hole 14 is provided as a main part thereof.

As shown in FIGS. 2 and 3, wiring patterns 5 (5 a, 5 b) and conductor pads 6 are formed on the surface of the insulating substrate 1 in the flexible printed wiring board 10.
Of the wiring patterns 5, a main body wiring pattern 5 b constituting a substantial main part of the electric circuit system is formed in the main body wiring area 7. A lead wiring pattern 5a is formed between the main body wiring pattern 5b and the conductor pad 6 so as to electrically connect the two. Here, in order to simplify the illustration in FIG. 2, only one lead wiring pattern 5 a is drawn, but actually, at least one lead wiring pattern 5 a is provided for one conductor pad 6. Needless to say, all conductor pads 6 are provided so as to be continuous.

A cover layer 2 is formed so as to cover almost the entire surface of the insulating substrate 1 and the wiring pattern 5. In the cover layer 2, one opening 8 having an area of 15000 μm ² or more for exposing the surface of the conductor pad 6 is provided for each conductor pad 6. Further, a fixing bolt hole 4 and an alignment hole 14 are provided so as to penetrate the cover layer 2 and the insulating substrate 1.
The surface of each conductor pad 6 exposed at the opening 8 is covered with a cover as shown in FIGS. 1 to 4 and particularly FIG. A contact bump 3 made of a conductive material and having a predetermined height h from the surface of the conductor pad 6 is provided so as to protrude higher than the outermost surface of the layer 2.

  On the other hand, in the printed wiring board 20 which is a counterpart of the connection of the flexible printed wiring board 10, as shown in FIG. 4 and in particular FIG. For example, an insulating substrate 21 made of a so-called glass epoxy base material, a connection pad 22 formed on the surface thereof, a lead wiring pattern 23 connected to the connection pad 22 and a wiring pattern body (not shown), and fixing A bolt hole 24, a cover layer 25, an opening 26 provided at every predetermined position of the cover layer 25 to expose the surface of the connection pad 22, and an alignment hole 27 are provided. Here, in FIG. 4, the cover layer 25 is omitted in order to make the illustration simple and easy to understand.

In the flexible printed wiring board 10 according to the embodiment of the present invention, the contact bumps 3 are pressed against the connection pads 22 formed on the surface of the printed wiring board 20 which is an external connection partner. Are in contact with each other, so that an electrical connection with the connection pad 22 is established. The pressing force (load applied) is applied to the lower surface from the inner upper plate 11 and the outer upper plate 31 through the elastic sheet 9 provided so as to be bonded to the back surface of the flexible printed wiring board 10. It is applied to the flexible printed wiring board 10 supported by the board 12 and the outer layer lower board 32. Therefore, even if a variation in the height h that cannot be ignored occurs in the contact bump 3, the variation in the height h is absorbed by the elastic deformation and bending of the elastic sheet 9 and the insulating base material 1 to ensure It is possible to secure the connection state.
That is, in this flexible printed wiring board 10, the contact bumps 3 themselves are directly formed on the printed wiring board 20 of the other party of connection without requiring any separate connector parts or microsprings. By functioning as a connector member for electrical connection with the connection pad 22, it is possible to use a separate connector, a microspring, etc. as in the prior art, and a connection process such as mounting and soldering of the connector. It can be omitted completely.

  Moreover, in the flexible printed wiring board integrated connector structure according to the embodiment of the present invention, which uses such a flexible printed wiring board 10 as one of the main components, the printed wiring board 20 which is a counterpart of connection. The flexible printed wiring board 10 is disposed facing the printed wiring board 20 so that the contact bumps 3 of the flexible printed wiring board 10 are pressed against the connection pads 22 of the flexible printed wiring board 10, and the flexible printed wiring board 10. With the elastic sheet 9 superimposed thereon, the elastic sheet 9, the flexible printed wiring board 10, and the printed wiring board 20 are sandwiched and held between the inner layer upper plate 11 and the inner layer lower plate 12, Further, an outer layer upper plate 31 is arranged on the inner layer upper plate 11 and below the inner layer lower plate 12. The outer layer lower plate 32 is arranged, and a nut 34 is attached to the tip of the fixing bolt 33 and fastened and fixed with an appropriate torque, whereby the contact bump 3 and the connection pad 22 are electrically connected. Is set so that it can be held more reliably and permanently.

  Next, each component in the flexible printed wiring board according to the embodiment of the present invention will be described in more detail.

The insulating base material 1 is a base material for a so-called copper-clad film substrate made of a material having a predetermined flexibility such as a polyimide resin film. In addition to polyimide, the insulating substrate 1 is made of a material generally used as a substrate material for flexible printed wiring boards, such as liquid crystal polymer (LCP), polyethylene terephthalate, and polyetheretherketone. Can be used.

However, if the insulating substrate 1 is too rigid, local bending (flexibility) to absorb variations in the thickness and flatness of the printed wiring board 20 to be connected and the thickness of the connecting pads 22 is achieved. ) Cannot be obtained, and as a result, there is a possibility that a reliable connection state cannot be ensured for all the connection parts. Moreover, in addition to the rigidity of the insulating substrate 1, when the rigidity of the wiring pattern 5 formed on the surface thereof is too high, the flexible printed wiring board 10 on which the wiring pattern 5 is formed can be bent (flexibility). There is a possibility that it becomes an obstructive factor.
Therefore, the thickness of a conductor film such as a copper foil used as a material for forming the wiring pattern 5 is set to 25 μm or less, and the total thickness of the conductor film and the insulating substrate 1 is set to 150 μm or less. It is desirable.
Even if the insulating base material 1 is made thin, if the material itself has extremely high rigidity, such as an iron plate, it becomes impossible to obtain the above-mentioned local bending. From this viewpoint, it is desirable that the material of the insulating substrate 1 has an elastic modulus of 10 GPa or less. It is polyimide, liquid crystal polymer, polyethylene terephthalate, etc. that meet the above conditions. From the same viewpoint, it is desirable that the material of the cover material 2 has an elastic modulus of 10 GPa or less.
Furthermore, when the flexible printed wiring board 10 is a multilayer flexible printed wiring board having two or more wiring layers, or when the contact bumps 3 conform to a so-called fine pitch connector specification with a pitch of 1 mm or less. The conductor film for forming the wiring pattern 5 is made as thin as possible within a range that does not impede its electrical and mechanical requirements, and the thickness of the insulating substrate 1 is 50 μm or less. In addition, the thickness of the cover layer 2 such as a solder resist provided as the outermost layer is preferably 30 μm or less.
Alternatively, the flexible printed wiring board generally can change its overall flexibility greatly depending on the wiring density and pattern shape such as the wiring pattern formed on the surface thereof. It is desirable to appropriately set the specifications such as the thickness and material of the flexible printed wiring board 10 in consideration of the flexibility.

The cover layer 2 is provided so as to cover the surface of the wiring pattern 5 and the insulating substrate 1 as a so-called protective layer such as a photo solder resist, and mechanical, thermal, chemical damage, etc. It is a layer for protecting the surface and ensuring the electrical insulation of those surfaces. Basically, the material and specifications of the cover layer 2 itself may be general ones. However, as described above, the cover layer 2 needs to be accurately provided with the opening 8 for exposing the surface of each conductor pad 6 over an area of at least 15000 μm ² or more. In addition, when there is a possibility that the cover layer 2 becomes an obstacle to local bending of the flexible printed wiring board 10 as described above, the cover layer 2 is made of a material having the elastic modulus as described above and is thin. is required.

As shown in FIG. 5A, the contact bump 3 has a top portion higher than the outermost surface of the cover layer 2 over a predetermined dimension on the surface of the conductor pad 6 exposed at the opening 8. It is provided in a protruding shape having a height h from the surface of the conductor pad 6 so as to protrude.
The contact bump 3 includes a bump body 3a made of a conductive material, and a coating having a thickness of 0.01 μm or more made of gold (Au) or a gold alloy provided so as to cover the outermost surface of the bump body 3a. Layer 3b.

The bump body 3a, which is a substantial body portion of the contact bump 3, may be formed by a plating method or may be formed by a printing method. When formed by an electrolytic plating method or an electroless plating method, for example, copper plating, nickel (Ni) plating or the like can be used, and when formed by a printing method, for example, a copper (Cu) paste, It is possible to use a conductive resin paste formed by mixing (dispersing) a metal in a resin filler, such as a copper (Cu) -based alloy paste that is cured by heat treatment after printing.
However, when the height h of the contact bump 3 is relatively large, for example, 30 μm or more, the printing method is adopted rather than the plating method from the viewpoint of shortening the time required for the formation process. It is desirable.

  The coating layer 3b is provided on the surface of the bump body 3a in order to enhance the repetitive connection property of the contact bump 3 as a connector contact member and the adhesion of the connection, and to further reduce the contact resistance of the contact. It is made of gold (Au) or an alloy thereof formed by an electrolytic plating method or an electroless plating method. Alternatively, the coating layer 3b may be not only a single layer of gold (Au) plating but also a layer (not shown) formed by laminating nickel (Ni) plating and gold (Au) plating.

  Here, when this flexible printed wiring board 10 (contact bump 3 thereof) is used for an application that is required to withstand repeated detachability like a connector terminal that can be frequently attached and detached, The contact bump 3 is strongly required to have durability against mechanical stress applied during repeated attachment / detachment, mechanical strength, rigidity, and the like. In addition, even when used for an application in which a semi-permanent connection is maintained, the contact bump 3 is always reliable in order to ensure a good electrical connection over a long period of time. In addition, it is desirable that the desired connection state is maintained with respect to the mating connection pad 22.

Even if this contact bump 3 is cut in a direction parallel to the bottom surface at any height from the bottom surface, such as a spindle shape, a spindle shape, or a tapered column shape, the shape of the cut surface is similar to the shape of the bottom surface. It is provided in an outer shape that forms a shape. As such a shape, in addition to the substantially hemispherical shape shown in FIGS. 1 to 5, a truncated hemisphere having a flat top surface, a tapered columnar shape having a flat top surface (a truncated cone). Shape), a tapered polygonal column shape having a flat top surface (a truncated polygonal pyramid shape), or a dome shape having a flat top surface that is elliptical or oval in plan view is also possible. .
In any shape, the wider the tip or top surface of the contact bump 3, the larger the contact area with the connection pad 22 of the mating printed wiring board 20 can be secured. It can be expected to ensure the electrical connection. However, on the other hand, it tends to be difficult to align with the mating connection pad 22, and if the alignment is not accurately performed with a predetermined accuracy, the tip of the contact bump 3 is seriously damaged. Alternatively, a part of the top surface is put on the surface of the cover layer 25 of the printed wiring board 20 of the other party to be connected, and there is a high possibility that the connection pad 22 cannot be contacted and connection failure is caused. . Therefore, in order to prevent such inconvenience, in actual product design and the like, the formation position accuracy of the contact bumps 3 on the flexible printed wiring board 10 and the formation of the connection pads 22 on the other printed wiring board 20 are the same. It is desirable to determine the outer shape and outer dimensions of the contact bump 3 to be more appropriate in consideration of the position accuracy, the pattern shape, and the alignment accuracy between the two.

As a preferable dimension setting of the height h of the contact bump 3 from the outermost surface of the conductor pad 6, the outermost surface of the conductor pad 6 on which the contact bump 3 is formed is used as a reference (that is, height = 0). Assuming that the height to the outermost surface of the cover layer 2 is a and the height from the outermost surface of the connecting pad 22 of the printed wiring board 20 to be connected to the outermost surface of the cover layer 25 is b, the height of the contact bump 3 H (unit: μm) is
h> (a + b) ± 50 μm
It is desirable to set so as to satisfy.

In the above conditional expression, when a large load is applied, the gap between the two wiring boards cannot be approached by pressing until the sum of the thickness of the cover layer 2 and the thickness of the cover layer 25 is less than this (this is (Corresponding to a + b on the right side of the above conditional expression) and contact bumps 3 and connection pads due to variations in height of the contact bumps 3 and variations in local thickness of the insulating substrate 1 Is set by taking into account a margin (this corresponds to ± 50 (μm) on the right side of the above conditional expression) to avoid the possibility that a good contact state with 22 cannot be reliably obtained. Is.
As a specific numerical aspect of the height h, for example, the height a from the outermost surface of the connection pad 22 in the printed wiring board 20 to the height a up to the outermost surface of the cover layer 2 in the flexible printed wiring board 10 is covered. Considering the height b to the outermost surface of the layer 25 and various specifications of the connection pads 22 and the wiring pattern 5 in the printed wiring board 20, it is desirable that the thickness be 20 μm or more.

Here, the following two points are required to securely connect the contact bump 3 to the mating connection pad 22.
(1) The variation in height between adjacent contact bumps 3 can be absorbed by locally deflecting the insulating base material 1 by the pressing force applied via the elastic sheet 9.
(2) Local variations in the thickness of the insulating base material 1 in the region where the contact bumps 3 are arranged, the insulating base material 1 or the holder 30 holding the insulating base material 1 or the printed wiring board of the other party The variation in the apparent thickness of the insulating base material 1 caused by the overall distortion or warpage of the insulating base material 20 is caused to bend the entire insulating base material 1 by the pressing force applied through the elastic sheet 9. It can be absorbed.

Among the above factors, the factor that has the greatest influence on (1) is the variation in the height h of the contact bump 3, and what is important for absorbing this variation is that of the elastic sheet 9 as described above. In addition to factors such as the amount of elastic deformation (or elastic modulus and thickness in other dimensions), there is an interval L between adjacent contact bumps 3 as shown in FIG.
That is, as schematically shown in FIG. 7, unless the insulating base material 1 is expected to stretch, the height of the height of the adjacent contact bumps 3 is equal to or greater than the distance L between the adjacent contact bumps 3 at the maximum. The difference Δh cannot be absorbed. In general, an insulating base material for a flexible printed wiring board such as a polyimide resin film is generally made of a material that can obtain very little elongation. Therefore, when the height difference Δh is larger than the distance L, a connection failure occurs between the lower contact bump 3 and the corresponding connection pad 22.
In order to avoid such an inconvenience, assuming that the maximum variation amount of the height h of the contact bump 3 is Δh and the interval between the adjacent contact bumps 3 is L, the interval L is expressed by the following relationship. It is desirable to set the value as determined by the formula.
L ≧ 2.5 · Δh
For example, when the variation (distribution) in the height of the contact bump 3 is ± 50 μm, if 100 (= 50 + 50) is substituted for Δh in the above relational expression, L ≧ 250 μm. Therefore, in this example, it is desirable to set the distance L between the contact bumps 3 to a dimension of 250 μm or more.
By setting the distance L between the contact bumps 3 to an appropriate value in this way, even if a variation in height occurs in the contact bumps 3 as schematically shown in FIG. Absorbing by elastic deformation and local bending of the insulating base material 1, it becomes possible to make sure that all the contact bumps 3 are connected to the mating connection pads 22 respectively.

Of the above, the factor that has the greatest influence on (2) is the thickness of the elastic sheet 9.
That is, as schematically shown in FIG. 9, the thickness of the elastic sheet 9 is t, the flatness of the portion of the mating printed wiring board 20 where the connection pads 22 are arranged is P μm, and flexible printed wiring. When the maximum variation amount of the height of the contact bump 3 on the plate 10 (that is, the difference in height between the contact bump 3-1 having the maximum height and the contact bump 3-2 having the minimum height) is S μm, the elastic body The thickness t μm of the sheet 9 is desirably set to a value determined by the following relational expression.
t ≧ 1.3 (P + S)

  A coating layer 3b is provided so as to cover the entire outermost surface of the bump body 3a. The coating layer 3b is made of gold (Au), white gold which is an alloy of gold and silver (Ag), yellow gold which is an alloy of gold and copper, silver or silver alloy, or the like. It is a coating layer for contact pieces having a thickness of 01 μm or more. That is, when the contact bump 3 comes into contact with the mating connection pad 22, in order to reduce the contact resistance and avoid the occurrence of contact failure or the like, such a coating made of gold, its alloy, silver or the like is used. It is desirable to form the layer 3b on the outermost surface of the contact bump 3. In addition, it is desirable to provide a coating layer 3b made of a stable material such as gold or an alloy thereof from the viewpoint of suppressing the progress of oxidation, secular change and deterioration of the contact surface. However, this coating layer 3b is not essential, and for example, the outermost surface of the bump body 3a is required as a connector member for electrical connection between the flexible printed wiring board 10 and the printed wiring board 20 of the counterpart of the connection. Of course, it may be omitted if it already satisfies the conditions such as contact resistance and durability.

  In the flexible printed wiring board 10, the alignment holes 14 are provided at two or more positions so as to penetrate the elastic body sheet 9, the cover layer 2, and the insulating substrate 1. Also, the printed wiring board 20 and the inner lower layer 12 of the other party of the connection are provided at two or more positions in the same positional relationship, and by inserting the alignment pins 13 into the alignment holes 14, flexible The printed wiring board 10 is set so that the printed wiring board 10 and the connected printed wiring board 20 can be positioned and sandwiched between the inner layer upper board 11 and the inner layer lower board 12. In the present embodiment, the plurality of contact bumps 3 are provided at three locations around the area where the matrix-like array is formed. Needless to say, the present invention is not limited to this. In addition to this, for example, a plurality of contact bumps 3 can be provided at the four corners around the area where the matrix is arranged in a matrix, for a total of four places, or at more positions. It is. Alternatively, it is possible to provide a plurality of contact bumps 3 at two locations on the diagonal line of the region where the plurality of contact bumps 3 are arranged in a matrix.

In the flexible printed wiring board 10, the fixing bolt holes 4 are provided at two or more positions so as to penetrate the elastic body sheet 9, the cover layer 2, and the insulating base material 1. Further, the outer layer upper plate 31, the inner layer upper plate 11, the printed wiring board 20, and the inner layer lower plate 12 are also provided at two or more positions in the same positional relationship, and are fixed to the fixing bolt holes 4. The bolt 33 is inserted, and the nut 34 is fastened and fixed to the exposed end of the outer layer upper plate 31 through a spring 35 with a washer. While the printed wiring board 20 is sandwiched and held between the inner layer upper plate 11 and the inner layer lower plate 12, they are mechanically applied while applying an appropriate load between the outer layer upper plate 31 and the outer layer lower plate 32. It is set to be able to hold.
In the present embodiment, the plurality of contact bumps 3 are provided at two locations in the substantially central portion on the left and right of the region in which the plurality of contact bumps 3 are arranged in a matrix, but it is needless to say that the present invention is not limited to this. Yes. In addition to this, for example, a plurality of contact bumps 3 can be provided at the four corners around the area where the matrix is arranged in a matrix, for a total of four places, or at more positions. It is. Alternatively, it is also possible to provide a plurality of contact bumps 3 at two locations on the diagonal line of a region in which a matrix is arranged.

The elastic sheet 9 absorbs variations in the heights of the contact bumps 3 formed in the array and variations in the thickness of the insulating base material 1 to the connection pads 22 of the printed wiring board 20 of the connection counterpart. In order to securely connect all the contact bumps 3, they are arranged on the back surface of the insulating substrate 1.
This elastic sheet 9 is flexible so as to obtain an elastic deformation amount capable of absorbing at least the variation in the height of the contact bump 3 and the variation in the thickness of the insulating base 1 as described above. It must be a thing.
As such a material, it is desirable to have an elastic modulus of 100 MPa or less. Further, regarding the lower limit value of the elastic modulus, it is difficult to unambiguously define a desirable numerical aspect, but qualitatively, all the variations of the height of the contact bump 3 are absorbed and absorbed. In order to obtain a reliable connection of the contact bumps 3 to the connection pads 22, local deflection that can absorb variations in the height of the contact bumps 3 must be overcome by overcoming the bending stress of the insulating substrate 1. Therefore, the elastic modulus corresponding to such an elastic force is a substantial lower limit value.
If the elastic sheet 9 is too thin, it can effectively absorb variations in the height of the contact bumps 3, variations in the thickness of the insulating substrate 1, and the printed wiring board 20. Therefore, it is necessary to have a thickness that can absorb these variations. A desirable numerical embodiment of such thickness is 50 μm or more.
The material of the elastic sheet 9 can be selected from various options depending on the environment and application in which the elastic sheet 9 is used. For example, a silicone resin or a urethane resin is applicable.

  The holder 30 includes an outer layer upper plate 31, an outer layer lower plate 32, a fixing bolt 33, and a nut 34 as main parts thereof. The outer layer upper plate 31 has two or more fixing bolt holes 4 through which two or more fixing bolts 33 provided perpendicularly to the surface of the outer layer lower plate 32 can be inserted. In the position. The flexible printed wiring board 10 and the printed wiring board 20 are sandwiched between the outer layer upper board 31 and the outer layer lower board 32 together with the elastic sheet 9 via the inner layer upper board 11 and the inner layer lower board 12. It is set to be held mechanically.

The flexible printed wiring board 10 is aligned using the holder 30, the inner layer upper board 11, and the inner layer lower board 12, and is kept in a state of being connected to the printed wiring board 20 of the other party of connection.
More specifically, the operation is as follows. First, as shown in FIG. 4, the flexible printed wiring board 10 is disposed opposite the printed wiring board 20 of the other party of connection, and then the elastic sheet as shown in FIG. 5. 9, the alignment hole 14 of the flexible printed wiring board 10 including the alignment hole 9, the alignment hole 27 of the counterpart printed wiring board 20, and the alignment hole 14 of the inner layer lower plate 12 are successively provided on the surface of the inner layer upper plate 11 in this order. The alignment pin 13 provided in such a manner is inserted. Thereby, between the inner layer upper board 11 and the inner layer lower board 12, all the contact bumps 3 and the connection pads 22 are connected in a regular manner to the flexible printed wiring board 10 and the other printed wiring board 20 to be connected. Thus, it can be in a state of being sandwiched by alignment. Further, the outer layer upper plate 31 is arranged on the inner layer upper plate 11, and the outer layer lower plate 32 is arranged under the inner layer lower plate 12 while the fixing bolt 33 is inserted into the fixing bolt hole 4. Further, the fixing bolt 33 is further inserted, so that the fixing bolt 33 penetrates the outer layer upper plate 31 and the tip portion protrudes upward. Then, a nut 34 is attached to the tip of the fixing bolt 33 protruding through the outer layer upper plate 31 via a spring 35 and tightened until a predetermined pressing pressure is obtained. Thus, between the outer layer lower plate 32 and the outer layer upper plate 31, the flexible printed wiring board 10 and the other printed wiring board 20 to be connected are connected to each other through the inner layer upper plate 11 and the inner layer lower plate 12. Presser pressure (
In a state where a pressing force or a load is applied, it can be reliably held mechanically for a long period of time.

Here, the alignment hole 14 of the inner layer lower plate 12 does not necessarily have to be manufactured with strict positional accuracy and dimensional accuracy, and sufficiently absorbs variations due to the positional accuracy and dimensional accuracy of the alignment pin 13 provided on the inner layer upper plate 11. It is only necessary to have a size as large as possible.
Further, between the inner layer upper board 11 and the inner layer lower board 12, the flexible printed wiring board 10 (the area where the contact bumps 3 are arranged) and the printed wiring board 20 (the connection pads 22 thereof are arranged). Area) and the elastic sheet 9 are sandwiched. For this reason, the length of the alignment pins 13 provided on the inner layer upper plate 11 is a state in which the total thickness of the alignment pins 13 is taken into consideration and a predetermined load (pressing force) is applied and held by the holder 30. In consideration of the fact that the elastic sheet 9 is compressed and deformed, the tip of the alignment pin 13 provided on the surface of the inner layer upper plate 11 protrudes below the inner layer lower plate 12 (that is, below the outer layer). It is necessary to design the thickness of the inner layer lower plate 12, the length of the alignment pin 13, and the like so that the inner layer lower plate 12 stays in the middle of the alignment hole 14 without hitting the upper surface of the plate 32.
The material of the inner layer upper plate 11 and the inner layer lower plate 12 may be metal or non-metal as long as the above positioning accuracy can be ensured, but the surface that contacts the flexible printed wiring board 10 or the printed wiring board 20. In order to avoid the occurrence of short circuit defects, it is desirable to apply an insulating coating or the like.
Further, the holder 30 is mechanical enough to prevent deformation even when a predetermined pressing force (load) is applied to the flexible printed wiring board 10 and the printed wiring board 20 via the inner layer upper plate 11 and the inner layer lower plate 12. It is desirable to have a material and thickness having strength.

According to the flexible printed wiring board 10 according to the embodiment of the present invention as described above, it is connected to the wiring pattern 5 on the surface of the insulating base material 1 and on the surface of the printed wiring board 20 of the connection partner. A contact bump 3 is formed which is brought into electrical contact with the connection pad 22 by being pressed against and contacted with the formed connection pad 22, and the contact bump 3 itself is a separate connector component. Without contact, etc., it directly contacts the connection pad 22 of the printed wiring board 20 which is an external connection partner, and functions as a connector member for electrical connection like a contact terminal of a connector component. In addition, if the height of the contact bumps 3 cannot be ignored, the thickness of the contact bumps 3 cannot be ignored, the thickness of the insulating substrate 1 or the other printed wiring board 20 cannot be ignored, warpage, and distortion. And the like, the variation is effectively absorbed by the elastic deformation of the elastic sheet 9, and all the contact bumps 3 are good for the connection pads 22 of the other printed wiring board 20. It is possible to ensure a good connection characteristic.
Further, it is possible to connect the flexible printed wiring board 10 to the flexible printed wiring board 10 without using any connection parts such as a connector (not shown) according to the prior art which is retrofitted separately from the flexible printed wiring board 10. The contact bumps 3 provided directly and the connection pads 22 provided directly on the printed wiring board 20 which is an external connection partner can form an electrical connection between the two wiring boards. it can. As a result, it is no longer necessary to use separate connector parts that have previously been a hindrance to fine pitch and high density wiring patterns, and a hindrance to simplification and cost reduction of connection structures. Further, the finer pitch and higher density of the wiring pattern 5b and the lead wiring pattern 5a and the contact bump 3 itself that are connected to the wiring pattern 5b due to the improvement of the connection density, and the connection structure by the contact bump 3 are simplified and the cost is reduced Both of these can be achieved together.

In the above embodiment, the wiring layer of the flexible printed wiring board 10 is a single layer (single-sided single layer) for simplification of illustration and explanation, but the two-layered (double-sided wiring), three-layered, or Of course, it is possible to use a multilayer wiring beyond that.
Of course, the wiring board to be connected to the flexible printed wiring board 10 according to the present invention is not limited to the rigid printed wiring board 20 as described above. In addition, although not shown in the drawings, for example, flexible printed wiring boards, ceramic wiring boards, glass wiring boards, or various display devices such as various semiconductor packages or liquid crystal display panels using them as wiring boards for mounting The wiring board of the other party of the connection can be used. In any case, there is a risk that damage due to the pressing force applied for reliable connection between the contact bump 3 and the connection pad 22, deformation or warping that the elastic sheet 9 cannot absorb can occur. If it is not, it can be applied as a wiring board for the other party without any problem.

  Moreover, in the said embodiment, as the holder 30 which comprises the principal part of the mechanism which hold | maintains the connection state in a flexible printed wiring board integrated connector structure, fixing of both wiring boards connected by what is called a bolt nut system. In the state where the pressing pressure is applied, the flexible printed wiring board 10 and the connected printed wiring board 20 are overlapped and connected in parallel with a predetermined accuracy and with a uniform pressure. Any structure other than the bolt and nut structure, such as a latch-type fastener, can be used as long as the structure can be stably maintained. Also, the material may be metal or non-metal, but depending on the temperature band, frequency band, etc. of the flexible printed wiring board 10 where it is used, heat resistance is required, or rather non-metal due to demands on electrical characteristics. There are cases where it is desirable to be, so it may be used properly according to these various requests.

  In the above embodiment, the case where the fixing bolt 33 is provided on the surface of the outer layer lower plate 32 and the fixing bolt hole 4 is provided in the outer layer upper plate 31 is described. 33 may be provided on the surface of the outer layer upper plate 31 and the fixing bolt hole 4 may be provided on the outer layer lower plate 32. Or although illustration is abbreviate | omitted, the fixing bolt hole 4 is provided in both the outer-layer upper board 31 and the outer-layer lower board 32, the fixing bolt 33 is penetrated in both of them, and the nut 34 is each provided in the both ends. You may make it fix by tightening.

  A flexible printed wiring board and a flexible printed wiring board integrated connector structure as described in the above embodiment were produced.

  As the insulating substrate 1, a liquid crystal polymer film having a Young's modulus of 2900 MPa was used. A copper foil having a thickness of 12 μm was bonded to both the front and back surfaces of the insulating base material 1, and the copper foil on one side was patterned to form a wiring pattern 5 (5 a, 5 b) and a conductor pad 6. . The conductive pads 6 were formed by arranging so-called round pads having a diameter of 0.4 mm in a matrix at a pitch of 0.8 mm. Further, a photo solder resist film was formed as a cover layer 2 having a thickness of 20 μm on both surfaces of the outermost layer. The cover layer 2 was provided with a circular opening 8 having a diameter of 0.3 mm. The surface of the conductor pad 6 was exposed from the opening 8.

A conductive copper paste in which copper (Cu) powder is dispersed in a resin filler is printed and formed on the surface of the conductor pad 6 of the flexible printed wiring board 10 by screen printing, and then cured by heat treatment. A bump body 3a having an outer shape of almost hemisphere and a height protruding from the surface of the cover layer 2 of 180 μm was formed. Then, the surface of the bump body 3a is subjected to an activation treatment as a pretreatment, and then, by electrolytic plating, a nickel (Ni) plating with a thickness of 2.0 μm and a gold (Au) plating with a thickness of 0.3 μm are formed. A laminated coating layer 3b was formed.
Then, an elastic sheet 9 made of foamed silicone rubber having a thickness of 1 mm and a Young's modulus of 10 MPa was bonded to the back surface of the area where the contact bumps 3 were arranged in the flexible printed wiring board 10.

  On the other hand, as a connection partner wiring board, a cover layer 25 having an opening 26 for exposing and exposing connection pads 22 having a diameter of 0.5 mm at the same 0.8 mm pitch as the flexible printed wiring board 10. The formed rigid printed wiring board 20 was prepared.

  Then, after aligning the alignment hole 14 with the alignment hole 14 of the flexible printed wiring board 10 and the connected printed wiring board 20 through the alignment pins 13, the flexible printed wiring board 10, the inner layer upper board 11, and the inner layer lower board are aligned. The fixing bolt hole 4 is passed through the fixing bolt hole 4 of 12 and the fixing bolt hole 24 of the printed wiring board 20, and the fixing bolt 33 is passed through the fixing bolt hole 4 of the outer layer upper plate 31, By tightening the nut 34 to the protruding tip via a spring 35, a state in which a load of 0.1 kg per contact bump 3 is applied to the connection pad 22 is mechanically held. It was.

  The electrical connection of the contact bumps 3 of the flexible printed wiring board 10 according to this embodiment to the connection pads 22 of the counterpart printed wiring board 20 is very good with reduced contact resistance. Was confirmed. It was also confirmed that the connection state can be kept stable.

  In addition, the flexible printed wiring board 10 manufactured in the above-described embodiment has the contact bumps 3 and the like that can perform substantially the same function as the connector component at the same time in the manufacturing process of the flexible printed wiring board 10 itself (or Since it can be built on the flexible printed wiring board 10 in parallel, it is connected using a connector or a micro spring which is a conventional separate connection component having the same connection density as the contact bump 3. Compared with the case where it performed, it became possible to reduce the whole manufacturing cost to 1/2 or less.

  In addition, by using a fine pitch-compatible etching technique or the like, for example, when a wiring pattern 5 or the like is formed by patterning a copper foil having a thickness of 8 μm, a wiring pattern with a 30 μm pitch (line / space = 15 μm / 15 μm) 5 can be formed, and for example, when the contact bumps 3 having a height of 80 μm are designed, three rows of contact bumps 3 can be formed with an arrangement pitch of 0.3 mm. . This means that the connection density in the case of the contact bump 3 is about three times as large as the connection terminal arrangement design limit in the case of a 0.5 mm pitch area type connector according to the prior art. According to the connection structure using the contact bump 3 in the flexible printed wiring board 10 according to the embodiment, it means that a remarkably high connection density can be realized.

  Further, even if the height of the contact bump 3 on the flexible printed wiring board 10 is varied or the other printed wiring board 20 is uneven in thickness, distorted or warped, the elastic sheet 9 can be The existence can absorb and alleviate these variations, and the load can be distributed evenly and applied to the contact bump 3, so that the occurrence of connection failure of the contact bump 3 can be greatly reduced. It became.

Further, in the conventional connector, in general, while the insertion / removal (removal) with respect to the connection pad of the other party is repeated, the probability of causing a connection failure due to the deformation of the contact bump increases, but the contact bump according to the embodiment of the present invention 3, since the elastic sheet 9 is elastically deformed in combination with the flexibility of the flexible printed wiring board 10, the load (compressive stress) applied to the contact bumps 3 is moderately relaxed and uniformed, and the occurrence rate of contact failure Can be greatly reduced. In the case of the present embodiment, the insertion / extraction life of the contact bump 3 is about 2.5 times that of the case where the elastic sheet 9 is not used at all, which is remarkably improved.
Further, in the holder 30, since the spring 35 is interposed between the nut 34 and the outer layer upper plate 31, a load that is continuously applied to keep the flexible printed wiring board 10 and the printed wiring board 20 in a connected state. (Pressing force) can be made constant more reliably.

  In the above-described embodiment, a conductive paste containing copper powder is used to form the contact bumps 3. However, the present invention is not limited to this. In addition, it is possible to obtain conductivity according to the application, and it can be formed into a predetermined shape, and more preferably, the surface has good mechanical special characteristics and electrical characteristics by electrolytic plating or electroless plating. If the material is such that the coating layer 3b can be formed, the contact bumps 3 are directly formed on the connection pads 22 by, for example, copper (Cu) plating or nickel (Ni) plating, and then the surface thereof is made of gold. Also by performing (Au) plating or the like, it is possible to obtain the contact bump 3 having good mechanical characteristics and electrical characteristics as in the above embodiment. However, when forming by plating method, it is necessary to define the shape as the bump using a photo negative dry film etc., and to deposit the metal plating for the volume on the non-pattern part of the photo negative dry film In general, the time, material and economic costs spent on its production tend to increase significantly compared to printing methods. From this point of view, it is considered that it is more desirable to form the contact bumps 3 by a printing method in mass production of the flexible printed wiring board according to the present invention.

DESCRIPTION OF SYMBOLS 1 Insulating base material 2 Cover layer 3 Contact bump 4 Fixing bolt hole 5 Wiring pattern 6 Conductor pad 7 Main body wiring area 8 Opening 9 Elastic body sheet 10 Flexible printed wiring board 11 Inner layer upper board 12 Inner layer lower board 13 Alignment pin 14 Alignment Hole 20 Connected printed wiring board 21 Insulating substrate 22 Connection pad 23 Lead wiring pattern 24 Alignment hole 25 Cover layer 26 Opening 27 Alignment hole 30 Holder 31 Outer layer upper plate 32 Outer layer lower plate 33 Fixing bolt 34 Nut 35 Spring

Claims (6)

A flexible printed wiring board having a wiring pattern formed on the surface of an insulating substrate,
On one side of the insulating base material, it is continuous with the wiring pattern and is pressed against and contacted with the connection pads arranged on the surface of the wiring board of the connection partner. Protruding contact bumps that are arranged so as to directly make electrical connections themselves and function as connector members for electrical connection with the connection pads of the wiring board of the other end of the connection;
A flexible printed wiring board comprising: an elastic sheet provided on a surface opposite to the one surface on which the contact bumps are arranged in the insulating base material. In the flexible printed wiring board according to claim 1,
The elastic sheet is disposed in a region including a region corresponding to a region where the contact bumps are arranged and formed on a surface opposite to the one surface on which the contact bumps are arranged, and the height of the contact bumps is increased. A flexible printed wiring board comprising a material that can be elastically deformed with a deformation amount equal to or greater than a maximum variation in thickness. In the flexible printed wiring board according to claim 1 or 2,
On one side of the insulating base material, a cover layer covering the wiring pattern is provided,
The contact bump has a bottom surface that fits in an opening having an area of 15000 μm ² or more provided in a cover layer formed on one side of the insulating base material and is provided in the opening and has an overall height from the bottom surface. It has a height of 20 μm or more and is formed in an outer shape so that the shape of the cut surface is similar to the shape of the bottom surface, regardless of the height from the bottom surface in the direction parallel to the bottom surface. Is,
The flexible printed wiring board, wherein the elastic sheet has a thickness of 50 μm or more and an elastic modulus of 100 MPa or less. In the flexible printed wiring board according to any one of claims 1 to 3,
The wiring pattern has a thickness of 25 μm or less,
And the thickness including the thickness of the said insulating base material except the height of the said contact bump and the thickness of the said wiring pattern is 150 micrometers or less, The flexible printed wiring board characterized by the above-mentioned. The wiring pattern formed on one side of the insulating substrate and the wiring pattern are connected to the wiring pattern and pressed against and contacted with the connection pads arranged on the surface of the wiring board of the connection partner. Protrusions that are arrayed so as to directly make electrical connection with the connection pads themselves and function as connector members for electrical connection with the connection pads of the wiring board of the connection counterpart A flexible printed wiring board with contact bumps;
An elastic sheet provided on a surface opposite to the one surface on which the contact bumps in the insulating substrate are arranged;
The flexible printed wiring board is disposed facing the wiring board of the connection partner so that the contact bump is connected to the connection pad of the wiring board of the connection counterpart, and on the flexible printed wiring board. An inner layer upper plate disposed on the elastic sheet in a state where the elastic sheet is superposed on an area corresponding to an area where at least the contact bumps are arranged;
The flexible printed wiring board is disposed facing the wiring board of the connection partner so that the contact bump is connected to the connection pad of the wiring board of the connection counterpart, and on the flexible printed wiring board. In a state where the elastic sheet is superimposed on an area corresponding to an area where the contact bumps are arranged and formed, at least the area corresponding to the area where the connection pads are arranged and arranged under the wiring board of the other side of the connection An inner layer lower plate disposed in the area,
One of the inner layer upper plate or the inner layer lower plate, the elastic sheet, the flexible printed wiring board, and the wiring board of the other side of the connection are provided so as to align them as a whole. Alignment holes used to perform
An alignment pin that is provided upright on the surface of the inner layer upper plate or the inner layer lower plate that is not provided with the alignment hole, and that can be inserted into the alignment hole. By being inserted into the alignment hole and aligned, the contact bumps in the flexible printed wiring board are connected to the connection pads in the connection counterpart wiring board on the connection counterpart wiring board. The flexible printed wiring board is placed face-to-face and the elastic sheet is overlaid on the flexible printed wiring board, and the elastic sheet, the flexible printed wiring board, and the wiring board of the other end of the connection are It is characterized by being sandwiched between an inner layer upper plate and the inner layer lower plate. Lexical Bull printed circuit board integral connector structure. The flexible printed wiring board integrated connector structure according to claim 5, further comprising:
An outer layer upper plate disposed on the inner layer upper plate;
An outer layer lower plate disposed under the inner layer lower plate;
Any one of the outer layer upper plate or the outer layer lower plate, the inner layer upper plate, the elastic sheet, the flexible printed wiring board, the wiring board at the other end of the connection, and the inner layer lower board A fixing bolt hole provided so as to pass through,
A fixing bolt that is provided upright on the surface of the outer layer upper plate or the outer layer lower plate that is not provided with the fixing bolt hole and can be inserted into the fixing bolt hole, The front end portion that is exposed through the fixing bolt hole is provided with a fixing bolt provided with a thread so that the nut is screwed together, and the alignment pin is inserted into the alignment hole for alignment. Then, the flexible printed wiring board is arranged facing the connection printed wiring board so that the contact bumps are connected to the connection pads on the connected wiring board. The inner sheet upper plate, the elastic sheet and the flexible member are placed between the outer layer upper plate and the outer layer lower plate in a state where the elastic sheet is superposed on the outer sheet. The printed wiring board, the wiring board of the other party to be connected and the lower inner board are sandwiched, and the fixing bolt is inserted into the fixing bolt hole, and the nut is screwed into the screw thread at the tip of the fixing bolt. A flexible printed wiring board integrated connector structure characterized in that the above state is maintained by combining.

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