Patent Grant
9601853
This application is a National Stage of International Application No. PCT/JP2014/073377, filed Sep. 4, 2014, claiming priority based on Japanese Patent Application No. 2013-184071, filed Sep. 5, 2013, the contents of all of which are incorporated herein by reference in their entirety.
The present invention relates to a printed wiring board having pads for electrical connection at a connection end portion to be connected with another electronic component, such as a connector, and also relates to a connector that connects the printed wiring board with another wiring board.
Printed wiring boards are used for connection between electronic components in electronic devices, such as digital cameras, digital video camcorders, notebook-sized personal computers, cellular phones, and game machines. In accordance with reduction in weight, thickness and size of such electronic devices, it is also required to make printed wiring boards thin and small in themselves. However, if a printed wiring board is made thin and small, the holding force given by a connector to the connection end portion will be weak and troubles may possibly occur, including that the printed wiring board is disconnected from the connector and contact failure occurs during implementation such as due to reaction forces in wiring and impact of dropping or the like.
To prevent such disconnection of a printed wiring board, Patent Document 1 below describes providing notches at locations opposite to each other at a pair of parallel sides of a flexible printed wiring board, and fitting engagement parts provided on a connector into the notches thereby to hold the flexible printed wiring board in the housing of the connector.
In the disclosure of the above Patent Document 1, however, the sides formed with the notches are constituted only of a base film and coverlays which cover both surfaces of the base film, and the base film and coverlays are each formed of a thin film of polyimide. Therefore, when the thickness of the film is made thin in accordance with further reduction in thickness and size of the printed wiring board, a sufficient strength cannot be provided around the notches, and it will be difficult to ensure a sufficient holding force given by the connector to the printed wiring board.
The coverlay provided to cover the wirings at the upper surface side of the printed wiring board terminates at the rearward side (near side) of the pads in order to expose the pads for electronic connection at the connection end portion to be connected with another electronic component. According to the research by the present inventors, it has been confirmed that, if the flexibility of a printed wiring board is enhanced due to its thinning, locations along the terminated part of the coverlay will be base points of wirings' bending, which may readily trigger the wirings to break at those locations.
Accordingly, problems to be solved by the present invention include providing a printed wiring board which has excellent disconnection resistance and durability.
The printed wiring board according to a first aspect of the present invention, which is for solving the above problems, is a printed wiring board comprising: a base substrate; a plurality of pads for electrical connection that are disposed at one surface side of the base substrate and at a connection end portion to be connected with another electronic component; wirings that are connected with the pads; and an engageable part that is formed at the connection end portion and is to be engaged with an engagement part of the other electronic component in a direction of disconnection. The printed wiring board of the present invention is characterized in that the wirings are disposed at the other surface side of the base substrate opposite to the surface on which the pads are disposed and that the printed wiring board further comprises a reinforcement layer that is disposed at the one surface side of the base substrate and at a frontward side with respect to the engageable part when viewed in a direction of connection with the other electronic component, and that is formed integrally with any of the pads.
The printed wiring board according to a second aspect of the present invention, which is for solving the above problems, is a printed wiring board comprising: a base substrate; a plurality of pads for electrical connection that are disposed at one surface side of the base substrate and at a connection end portion to be connected with another electronic component; wirings that are connected with the pads; and an engageable part that is formed at the connection end portion and is to be engaged with an engagement part of the other electronic component in a direction of disconnection. The printed wiring board of the present invention is characterized in that the wirings are disposed at the other surface side of the base substrate opposite to the surface on which the pads are disposed and that the printed wiring board further comprises a reinforcement layer that is disposed at the one surface side of the base substrate and at a frontward side with respect to the engageable part when viewed in a direction of connection with the other electronic component, and that is formed separately from the pads.
In the present description herein, the term “frontward” or “front” refers to the direction toward the front-end side of the connection end portion of the printed wiring board, while the term “rearward” or “rear” refers to the opposite direction.
In the printed wiring board of the first aspect of the present invention, it is preferred to provide an insulating layer that covers a surface of the reinforcement layer.
In each of the printed wiring boards of the first and second aspects of the present invention, it is preferred that the reinforcement layer has the same thickness as that of the pads.
In each of the printed wiring boards of the first and second aspects of the present invention, it is preferred that the engageable part and the reinforcement layer are provided at each of both side edge parts of the connection end portion.
In each of the printed wiring boards of the first and second aspects of the present invention, it is preferred that the engageable part is a notched part formed at a side edge part of the connection end portion.
In each of the printed wiring boards of the first and second aspects of the present invention, it is preferred that the printed wiring board is a flexible printed wiring board.
The present invention also provides a connecter which connects any of the above-described printed wiring boards with another wiring board. The connector is characterized by comprising: a housing that has an insertion opening into which the connection end portion of the printed wiring board is inserted; a plurality of contacts that are provided to correspond to the plurality of pads of the printed wiring board inserted in the housing; and an engagement part that engages with the engageable part provided with the printed wiring board in the direction of disconnection of the printed wiring board.
In the connector of the present invention, it is preferred to provide an operative member for connection and disconnection of the contacts and the printed wiring board.
In the connector of the present invention, it is preferred that the operative member is a rotative member that is rotatably supported by the housing around a rotation axis in a width direction and is operative to: rotate in one direction thereby to connect the contacts with the pads of the printed wiring board; and rotate in the other direction thereby to disconnect the contacts from the pads of the printed wiring board.
In the connector of the present invention, it is preferred that the engagement part is a lock member that is configured such that, as the rotative member rotates in the one direction, the lock member engages with the engageable part, which is provided at least at one side edge part of the connection end portion of the printed wiring board, in the direction of disconnection of the printed wiring board, and as the rotative member rotates in the other direction, the engagement is released.
The printed wiring board of the present invention has a feature that the engageable part is provided at the connection end portion so as to be engaged with the engagement part of the other electronic component in the direction of disconnection as well as a feature that the reinforcement layer is provided at the one surface side of the base substrate and at the frontward side with respect to the engageable part. According to the features of the present invention, the strength of the printed wiring board frontward with respect to the engageable part can be enhanced, and a sufficient engagement force (disconnection resistance) with the engagement part of the other electronic component can be ensured even when the printed wiring board is made thin and small. Moreover, the printed wiring board of the present invention has a feature that the wirings connected with the pads are disposed at the other surface side of the base substrate. According to the feature of the present invention, a coverlay at the one surface side (the side provided with the pads) can be omitted, so that the wirings can be prevented from breaking due to bending of the wirings which would be converged at the terminated part of such a coverlay. Furthermore, according to such disposition of the wirings, wirings at the one surface side of the flexible printed wiring board can be omitted, and an advantage is thereby obtained that a wide space for mounting can be ensured when other electronic components such as chips are mounted on the one surface side.
Hereinafter, embodiments of the present invention will be described with reference to the drawings. While the description herein exemplifies a flexible printed wiring board (FPC) as a printed wiring board, the present invention is applicable to any other printed wiring board, such as a rigid flexible printed wiring board. In the description below, a specific example is described in which a flexible printed wiring board is inserted in a ZIF (Zero Insertion Force) connecter and used, but the printed wiring board of the present invention can also be used for a non-ZIF connector which utilizes the thickness of a printed wiring board to obtain a fitting force, and a backboard connector.
(Flexible Printed Wiring Board)
As shown in
The flexible printed wiring board 1 has a connection end portion 13, which is to be inserted in an insertion opening of a connector as will be described later, at least at one end portion in an insertion direction (direction of connection) I. The upper surface of the connection end portion 13 is formed thereon with a plurality of pads 15a and 17a for electrical connection that are disposed in a staggered arrangement to form front and rear two arrays 15 and 17 when viewed in the insertion direction I. As will be understood, the pads 15a and 17a may not be disposed in a staggered arrangement. In an alternative embodiment, positions of the pads 15a of the front array 15 in the width direction (direction crossing the insertion direction I) W may be the same as those of the pads 17a of the rear array 17 (see
The flexible printed wiring board 1 further has first wirings 9 connected with the pads 15a of the front array 15 and second wirings 11 connected with the pads 17a of the rear array 17. Both the first wirings 9 and the second wirings 11 are disposed at the opposite side of the base film 3 to the side provided with the pads 15a and 17a, i.e., disposed between the base film 3 and the lower surface side coverlay 7. Thus, both the first wirings 9 and the second wirings 11 are disposed at the back surface side of the base film 3 thereby to allow the upper surface side coverlay to be omitted. The first wirings 9 and the second wirings 11 are adjacent to one another in the width direction (direction crossing the insertion direction I) W and extend in the insertion direction (direction of connection) I to the connector. The first wirings 9 and the second wirings 11 can be formed of known conductive metal, e.g., copper or copper alloy. In addition, plated layers (e.g., copper plated layers) 43 may be formed on outer surfaces of the first wirings 9 and second wirings 11.
As shown in
As shown in
As shown in
As shown in
The reinforcement layers 31 and 32 are formed of the same material as that of the wirings 9 and 11. The reinforcement layers 31 and 32 may have the same thickness as that of the wirings 9 and 11, but can also be formed thicker or thinner than the wirings 9 and 11, provided that a necessary strength is obtained. In view of ensuring a sufficient disconnection strength, the width (length along the width direction W) of the reinforcement layers 31 and 32 may preferably be 100% or more of the width of the engageable parts 28 and 29. The length (length along the insertion direction I) of the reinforcement layers 31 and 32 can be appropriately set in accordance with various conditions (such as strength and material). The shape of the reinforcement layers 31 and 32 is rectangular in the embodiment shown, but the present invention is not limited thereto. In alternative embodiments, various shapes can be employed, such as a shape having an arc at least as a part thereof as shown in
The flexible printed wiring board 1 of the present embodiment with the above structure has a feature that the engageable parts 28 and 29 are provided at the side edge parts of the connection end portion 13 so as to be engaged with the engagement parts of another electronic component in the direction of disconnection as well as a feature that the reinforcement layers 31 and 32 are provided at the one surface side of the base film 3 and at the frontward side with respect to the engageable parts 28 and 29. According to the features of the present embodiment, the strength of the frontward side of the flexible printed wiring board 1 with respect to the engageable parts 28 and 29 can be enhanced, and a sufficient engagement force (disconnection resistance) with the engagement parts of the other electronic component can be ensured even when the flexible printed wiring board 1 is made thin and small. Moreover, the reinforcement layers 31 and 32 are formed integrally with the pads 15a thereby to allow the surface area of the reinforcement layers 31 and 32 to be large. In addition, since the reinforcement layers 31 and 32 are supported by the pads 15a, a higher disconnection resistance can be achieved compared with a case in which the reinforcement layers 31 and 32 are formed separately from the pads 15a.
The flexible printed wiring board 1 of the present embodiment has a feature that both of the first wirings 9 connected to the pads 15a of the front array 15 and the second wirings 11 connected to the pads 17a of the rear array 17 are disposed on the other surface (back surface) of the base film 3. According to the feature of the present embodiment, an upper surface side coverlay 5 as shown in
The flexible printed wiring board 1 of the present embodiment has a feature that the expanded-width parts 9a and 11a are provided at positions of the first wirings 9 and second wirings 11 corresponding respectively to the pads 15a and 17a. According to the feature of the present embodiment, even if the contacts of another electronic component to be in contact with the pads 15a and 17a are misaligned to some extent from the normal positions in the pads such as due to production error, the stable connection of the pads 15a and 17a with the contacts of the other electronic component can be maintained for a long period of time, because the thickness of a part of the flexible printed wiring board 1 to be in contact with the contacts can be uniform, i.e., the creep resistance can be improved. In particular, the expanded-width parts 9a and 11a may have the shapes corresponding to those shapes of the pads 15a and 17a, as in the present embodiment, thereby to more steadily obtain that effect.
The flexible printed wiring board 1 of the present embodiment has a feature that the reinforcement layers 31 and 32 have the same thickness as that of the wirings 9 and 11 located on the same plane. According to the feature of the present embodiment, the flexible printed wiring board 1 can have a sufficient thickness at locations to be in contact with the engagement parts of another electronic component, and the disconnection resistance of the flexible printed wiring board 1 can be steadily enhanced.
The flexible printed wiring board 1 of the present embodiment has a feature that the engageable parts 28, 29 and the reinforcement layers 31 and 32 are provided at both side edge parts of the connection end portion 13. According to the feature of the present embodiment, the disconnection resistance of the flexible printed wiring board 1 can be further enhanced, and more stable holding can be achieved.
(Method for Producing Flexible Printed Wiring Board)
An embodiment of a method for producing the flexible printed wiring board 1 shown in
First, as shown in
Next, as shown in
Then, a lower surface side coverlay 7 (see
Subsequently, gold plated layers 18 and 19 are formed on the surfaces of the pads 15a and 17a formed at the upper surface side, and both side edge parts of the connection end portion are partially removed such as using metal dies, thereby to form engageable parts 28 and 29 at the both side edge parts. The flexible printed wiring board 1 as shown in
(Flexible Printed Wiring Boards of Other Embodiments)
A flexible printed wiring board of another embodiment according to the present invention will then be described with reference to
The flexible printed wiring board 1 shown in
According to the flexible printed wiring board 1 of the present embodiment, the reinforcement layers 31 and 32 can enhance the disconnection resistance of the flexible printed wiring board 1. In addition, the insulating layers 34 and 35 can insulate the reinforcement layers 31 and 32 from the engagement parts of another electronic component. Therefore, even when the engagement parts of the other electronic component are connected to ground, the pads 15a for signals can be prevented from short-circuiting with the ground via the reinforcement layers 31 and 32 and the engagement parts of the other electronic component. Furthermore, such insulating layers 34 and 35 also serve as reinforcement members that enhance the strength around the engageable parts 28, 29, and can further enhance the disconnection resistance of the flexible printed wiring board 1.
Next, as shown in
In more detail, the reinforcement layers 31′ and 32′ can be formed of an insulating resin, e.g., polyimide, polyester, or polyethylene naphthalate. In the embodiment shown, the reinforcement layers 31′ and 32′ are each provided at outer side of the pads 15a and 17a in the width direction so as to extend from near side position of the pads 17a of the rear array 17 to the front side end position of the connection end portion 13 and to surround the engageable part 28, 29, but the reinforcement layers 31′ and 32′ may be provided only at frontward side parts with respect to the engageable parts 28 and 29 when viewed in the direction of connection with another electronic component.
According to such a flexible printed wiring board 1, the reinforcement layers 31′ and 32′ can enhance the disconnection resistance of the flexible printed wiring board 1. In addition, even when the engagement parts of the other electronic component are connected to ground, the pads 15a for signals can be prevented from short-circuiting with the ground via the reinforcement layers 31′ and 32′ and the engagement parts of the other electronic component.
Embodiments of the flexible printed wiring boards according to the present invention have been described hereinbefore, but the present invention is not limited to these embodiments and various modifications are possible.
(Connector)
The description will then be directed to a connector according to an embodiment of the present invention which connects the above-described flexible printed wiring board 1 to another wiring board.
As shown in
The housing 52 is formed of electrically insulating plastic and can be manufactured using a known injection molding method. The material may be appropriately selected in consideration of the dimensional stability, workability, cost, and the like. Examples of the material include in general polybutylene terephthalate (PBT), polyamide (66PA, 46PA), liquid crystal polymer (LCP), polycarbonate (PC), polytetrafluoroethylene (PTFE), and composite material thereof.
The housing 52 is provided with a required number of insertion channels in which the contacts 54 are inserted, and the rearward side of the housing 52 is provided with an insertion opening 60 into which the flexible printed wiring board 1 is inserted.
The contacts 54 can be manufactured using a known working method, such as press work and cutting work. The contacts 54, for which spring property, conductivity and other appropriate properties are required, can be formed of brass, beryllium copper, phosphor bronze, or the like. As shown in
As shown in
The operating member may be, other than the rotative member 56 as described above, a slider that is inserted into the housing to press the flexible printed wiring board to the contacts after the printed wiring board is inserted in the housing. Specifically, a connector 70 as shown in
In the connector 50 shown in
Tests for confirming the effects of the present invention were performed, which will be described below.
As Example 1, a printed wiring board having the structure shown in
As Example 2, a printed wiring board was experimentally manufactured as in Example 1 except that the insulating layers as shown in
As Example 3, a printed wiring board was experimentally manufactured as in Example 1 except that the reinforcement layers as shown in
As Comparative Example 1, a printed wiring board having the same structure as that of Example 1 was experimentally manufactured except that, as shown in
(Test of Disconnection Resistance)
The test of disconnection resistance was performed through: connecting each of the flexible printed wiring boards of Examples 1 to 3 and Comparative Example 1 with a connector having the structure shown in
(Test of Durability)
The test of durability was performed through: mounting a connector having the structure shown in
(Test Results)
Results of the test of disconnection resistance were as follows. Given that the load when the flexible printed wiring board of Comparative Example 1 was disconnected from the connector was represented by 100%, the load when the flexible printed wiring board was disconnected from the connector was 146% in Example 1, 168% in Example 2, and 115% in Example 3. It has thus been confirmed that the disconnection resistance of the flexible printed wiring board is improved by applying the present invention. Results of the test of durability were such that all the wirings were broken at locations along the terminated part of the upper surface side coverlay in Comparative Example 1, whereas such breaking did not occur in Examples 1 to 3.
As described above, according to the present invention, it is possible to provide a printed wiring board that exhibits excellent disconnection resistance and durability.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-184071 | Sep 2013 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2014/073377 | 9/4/2014 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2015/034016 | 3/12/2015 | WO | A |
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| Entry |
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| Japanese Office Action of JP Application No. 2013-184071 dated Sep. 16, 2014. |
| Japanese Office Action of JP Application No. 2013-184071 dated Feb. 3, 2015. |
| International Search Report of PCT/JP2014/073377 dated Sep. 30, 2014 [PCT/ISA/210]. |
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| Number | Date | Country | |
|---|---|---|---|
| 20160204532 A1 | Jul 2016 | US |
