EP2727443A1

EP2727443A1 - Printed board

Info

Publication number: EP2727443A1
Application number: EP12735656.6A
Authority: EP
Inventors: Naoki Ito; Yasunori NABETA
Original assignee: Yazaki Corp
Current assignee: Yazaki Corp
Priority date: 2011-07-01
Filing date: 2012-06-22
Publication date: 2014-05-07
Also published as: CN103548427A; KR20130140872A; JP2013016593A; JP5785005B2; WO2013005656A1

Abstract

A printed board 1 capable of suppressing the occurrence of defective continuity or the increase of contact resistance at a terminal contact part is provided. The printed board 1 is constructed such that an exposed surface of a conductor 5 formed on a surface of an insulative base member 3 is subjected to a plating, the conductor 5 subjected to the plating includes a terminal contact part 9 with which a complementary terminal contacts and a plating lead part 11 formed to be continuous to the terminal contact part 9, and a set range of at least an upper surface of an end portion of the plating lead part 11 is covered by protecting material.

Description

DESCRIPTION

PRINTED BOARD Technical Field

The present invention relates to a printed board and, in particular, relates to a technique of covering a plating lead part of conductive material formed on the surface of the base member of the printed board having flexibility. Background Art

For example, a patent literature 1 discloses a connector structure using a flexible printed board such as an FPC (flexible printed circuit). This kind of printed board is configured that, for example, a plurality of conductors wired in parallel on the surface of the base member of the circuit board are covered by an insulative resin film and one portions of the conductors are exposed from the insulative resin film at the one end side of the conductors. Such the printed board is inserted into a housing in a state of being fixed to a slider and the exposed conductor portions of the printed board are made in contact with a complementary terminal provided within the housing to thereby obtain electrical coupling state therebetween.

A plating lead part is usually formed at each of the exposed conductor portions of such the printed board. This plating lead part is formed to be continuous to a terminal contact part which contacts with the complementary terminal. The line width of the plating lead part is formed to be sufficiently smaller than that of the terminal contact part. This is because, since the outer periphery of the printed board is cut off at the time of manufacturing the printed board, the abrasion of a cutting equipment progresses rapidly when the line width of the plating lead part is large. Thus, the line width of the plating lead part is formed to be narrow in order to suppress the progress of the abrasion.

In most cases, such the printed board is subjected to the gold plating at the conductor exposed portions, that is, the terminal contact parts and the plating lead parts. When the conductors are subjected to the gold plating in this manner, the generation of oxide or corrosion product due to the contact of oxidation gas or corrosive gas with the conductors can be suppressed.

Citation List

Patent Literature

[PTL 1] Japanese Patent Publication No. JP-A-2003-45558

Summary of Invention

Technical Problem

Since the plating lead part is cut off at the end portion thereof together with the base member after being subjected to the gold plating, a cut surface not subjected to the gold plating is formed at the end portion of the plating lead part. Thus, the oxide or corrosion product may be generated at the cut surface. As a result, if the distance between the end portion of the plating lead part and the terminal contact part is short, the oxide or corrosion product generated at the end surface of the plating lead part may be adhered to the surface of the terminal contact part with which the complementary terminal contacts, so that there may arise defective continuity and the increase of contact resistance.

An object of this invention is to suppress the occurrence of defective continuity or the increase of contact resistance at a terminal contact part.

Solution to Problem

According to one aspect of the present invention, there is provided a printed board, comprising

an exposed surface of a conductor formed on a surface of an insulative base member, the exposed surface of the conductor being subjected to a plating, wherein

the conductor subjected to the plating includes a terminal contact part with which a complementary terminal contacts and a plating lead part formed to be continuous to the terminal contact part, and

a set range of at least an upper surface of an end portion of the plating lead part is covered by protecting material.

In this manner, since at least the upper surface of the end portion of the plating lead part is covered by the protecting material, the movement of the oxide or corrosion product generated at the end surface of the plating lead part to the terminal contact part can be prevented. Thus, the occurrence of the defective continuity with respect to the complementary terminal and the increase of contact resistance due to the oxide or corrosion product can be suppressed. Further, a film member having an adhesion layer formed on one major surface thereof may be used as the protecting material/and

the film member may be stuck to a region from a rear surface of the base member of the end portion of the plating lead part to an upper surface of the end portion of the plating lead part.

According to this configuration, since not only the upper surface of the end portion of the plating lead part but also the end surface thereof are covered by the film member, the generation of the oxide or corrosion product at the end surface of the plating lead part can be prevented. Thus, the occurrence of the defective continuity and the increase of contact resistance at the terminal contact part can be surely prevented. Further, since the film member is used as the protecting material, the sticking procedure can be performed in a shorter time as compared with a case of forming the adhesion layer by coating adhesive on the end portion, for example. Further, the protection layer having no surface irregularity or unevenness can be formed. In this case, a polyimide film, for example, may be used as the film member.

Still further, resin having hardenability and in a liquid or gel state may be used as the protecting material, and

the resin may be coated on the end portion of the plating lead part or the end portion of the plating lead part may be dipped within the resin to thereby form a resin layer on a region from a rear surface of the base member of the end portion of the plating lead part to the upper surface of the end portion of the plating lead part. According to this configuration, since the resin stuck on the end portion of the plating lead part by the dipping or coating can be hardened later, the resin layer having sealing property can be formed at a predetermined position. Thus, the plating lead part can be covered easily. In this case, ultraviolet curing resin, for example, may be used as the resin.

Still yet further, a film member having an adhesion layer formed on one major surface thereof may be used as the protecting material, and the film member may be stuck to the upper surface of the end portion of the plating lead part. In this case, when the film member is stuck so as to protrude toward the end surface from the upper surface of the plating lead part, for example, the movement of the oxide or corrosion product to the terminal contact part can be suppressed effectively. In this case, also the polyimide film, for example, may be used as the film member.

Advantageous Effects of Invention

According to the invention, it is possible to suppress the occurrence of defective continuity or the increase of contact resistance at a terminal contact part.

Brief Description of the Drawings

Fig. 1A is a top view showing a first embodiment in which the plating lead part of a printed board to which this invention is applied is covered.

Fig. 1 B is a side view showing a first embodiment in which the plating lead part of a printed board to which this invention is applied is covered.

Fig. 2 is a sectional diagram cut along a line ll-ll at a portion B in Fig. 1A.

Fig. 3A is a top view showing a second embodiment in which the plating lead part of a printed board to which this invention is applied is covered.

Fig. 3B is a side view showing a second embodiment in which the plating lead part of a printed board to which this invention is applied is covered.

Fig. 4 is a sectional diagram cut along a line IV-IV at a portion D in Fig.

3A.

Fig. 5A is a top view showing a third embodiment in which the plating lead part of a printed board to which this invention is applied is covered.

Fig. 5B is a side view showing a third embodiment in which the plating lead part of a printed board to which this invention is applied is covered.

Fig. 6 is a sectional diagram cut along a line VI-VI at a portion F in Fig.

5A.

Fig. 7 is a top view showing the entire configuration of the printed bard. Fig. 8A is an enlarged top view showing a portion G in Fig. 7.

Fig. 8B is an enlarged side view showing a portion G in Fig. 7.

Description of Embodiments

Hereinafter, embodiments of a printed board to which this invention is applied will be explained.

The printed board according to the embodiments of this invention is applied to a flexible printed board such as an FPC. As shown in Fig. 7, the printed board 1 according to the embodiments is configured that conductors 5 formed by metal foil (copper foil, for example) are wired in parallel and fixed on the surface of a flexible base member 3. The conductors 5 are covered by an insulative resin film 7. One portions (left side portions in Fig. 7) of the conductors 5 are exposed from the insulative resin film 7 at the one end side of the conductors. The insulative resin film 7 is formed by a polyimide film, for example.

The conductor portion G exposed from the insulative resin film 7 is shown in Figs. 8A and 8B. The conductor portion G includes a terminal contact part 9 and a plating lead part 11. The plating lead part 11 is formed to be continuous to the terminal contact part 9. The line width of the plating lead part 11 is formed to be sufficiently smaller than that of the terminal contact part 9. The terminal contact part 9 acts as a portion on which a not-shown complementary terminal is placed and is electrically made in contact therewith. The line width of the plating lead part 11 is set to be smaller than that of the terminal contact part 9 in order to suppress the abrasion of a cutting equipment for cutting off the outer periphery of the printed board 1 at the time of manufacturing the printed board 1.

The gold plating is performed on the exposed surface of each of the terminal contact part 9 and the plating lead part . Since the gold plating is performed in this manner, the generation of oxide or corrosion product due to the adhesion of oxidation gas or corrosive gas to the exposed surfaces can be prevented. The printed board 1 configured in this manner is inserted into a housing in a state of being fixed to a not-shown slider. Thus, a complementary terminal provided within the housing is pushed against the exposed terminal contact parts 9 of the printed board 1 to thereby obtain an electrical coupling state therebetween.

As explained above, since the end portion of the plating lead part 11 subjected to the gold plating is cut off in the manufacturing procedure of the printed board 1 , a cut surface not subjected to the gold plating is formed at the end portion of the plating lead part 11. Thus, the oxide or corrosion product may be generated at the cut surface due to the adhesion of the oxidation gas or corrosive gas to the cut surface of the plating lead part 1. In particular, when the distance between the terminal contact part 9 and the end portion of the plating lead part 11 is short, the oxide or corrosion product generated at the cut surface of the plating lead part 11 may move on and adhere to the upper surface of the terminal contact part 9, that is, the surface thereof contacting with the complementary terminal. In this case, since there is the oxide or corrosion product between the complementary terminal and the terminal contact part 9, there may arise defective continuity and the increase of contact resistance. In contrast, according to the embodiments of this invention, in order to prevent the movement of the oxide or corrosion product generated at the cut surface of the plating lead part 11 to the terminal contact part 9, it is characterized by forming a protection layer formed by protecting material at least on the upper surface of the plating lead part 11 at the end portion of the plating lead part 11. Further, according to the embodiments of this invention, in order to prevent the generation of the oxide or corrosion product at the cut surface of the plating lead part 11 , it is characterized by forming the protection layer formed by the protecting material on a region from the rear surface of the base member 3 of the end portion of the plating lead part 11 to the upper surface of the end portion of the plating lead part 11.

The first embodiment of this invention will be explained with reference to Figs. 1A, 1 B and 2. In this embodiment, a sheet-shaped film member 13 having an adhesion layer on one major surface thereof is used as the protection layer. The film member 13 is formed by two layers, that is, the adhesion layer 15 and a film layer 17. The adhesion layer 15 is placed between the film layer 17 and the plating lead part 11 , the base member 3. In this embodiment, such the film member 13 is stuck to the region from the rear surface of the base member 3 of the end portion of the plating lead part 11 to the upper surface of the end portion of the plating lead part 11. The sticking procedure of the film member 13 may be performed manually or automatically. Although a sheet member formed by a known polyimide film may be used as the film member 13, the configuration of the film member is not limited thereto so long as the adhering state between the film member 13 and the plating lead part 11 , the base member 3 is held and also the permeation of the oxidation gas or corrosive gas can be prevented. In this manner, since the film member 13 is stuck not only on the upper surface of the end portion of the plating lead part 11 but also on the region from the cut surface of the plating lead part 11 to the rear surface of the base member 3, the cut surface of the plating lead part 11 can be sealed completely by the film member 13. Thus, the generation of the oxide or corrosion product due to the contact of the oxidation gas or corrosive gas with the cut surface of the plating lead part 11 can be prevented, and also the occurrence of defective continuity and the increase of contact resistance at the terminal contact part 9 can be prevented.

Further, since the film member 13 is stuck to the end portion of the plating lead part 11 in a U-shaped manner in its section (as seen in Fig. 2), that is, so as to wrap the plating lead part 11 , the stuck area can be secured to be large. Thus, the stuck state of the film member 13 can be held stably. Furthermore, since such the film member 13 is used, the covering procedure can be performed easily and the protection layer having no surface irregularity or unevenness can be formed.

Next, the second embodiment of this invention will be explained with reference to Figs. 3A, 3B and 4. In this embodiment, constituent elements having the same configurations as those of the first embodiment are referred to by the common symbols, with explanation thereof being omitted. The explanation will be mainly be made as to constituent elements different from those of the first embodiment and characteristic portions of this embodiment. This embodiment differs from the first embodiment in a point that predetermined resin is employed as a member forming the protection layer in place of the film member 13. The resin used in this embodiment is liquid or gel resin having hardenability which is hardened by being subjected to a predetermined processing in the liquid or gel state. For example, there is known the ultraviolet curing resin which is hardened by being irradiated with ultraviolet in the liquid or gel state.

When such the kind of resin is employed, the resin can be hardened easily by being subjected to a predetermined processing after coating the liquid resin on the end portion of the plating lead part 11 or dipping the end portion of the plating lead part 11 within the liquid resin, for example. As a result, as shown in Fig. 4, a resin layer 19 can be formed easily not only on the upper surface of the end portion of the plating lead part 11 but also on the region from the cut surface of the plating lead part 11 to the rear surface of the base member 3.

Since the resin layer 19 formed in this manner can prevent the permeation of the oxidation gas or corrosive gas, this embodiment can attain the sealing effects as to the cut surface of the plating lead part 11 like the first embodiment. Thus, the generation of the oxide or corrosion product can be prevented and also the occurrence of the defective continuity and the increase of contact resistance at the terminal contact part 9 can be prevented. Further, in this embodiment, since the resin layer 19 is formed in the U-shaped manner (as seen in Fig. 4) at the end portion of the plating lead part 11 , the stuck area of the resin layer 19 can be secured to be large and hence the resin layer 19 can be held further stably. Furthermore, since the resin layer 19 can be formed in the liquid or gel state, it is possible to process many components at once, for example, and hence the workability can be improved.

Next, the third embodiment of this invention will be explained with reference to Figs. 5A, 5B and 6. In this embodiment, constituent elements having the same configurations as those of the first embodiment are referred to by the common symbols, with explanation thereof being omitted. The explanation will be mainly be made as to constituent elements different from those of the first embodiment and characteristic portions of this embodiment.

This embodiment is common to the first embodiment in a point that the film member 13 is employed as a member forming the protection layer but differs from each of the first and second embodiments in a point that the film member 13 is stuck only on the upper surface of the end portion of the plating lead part 11. In this embodiment, since the cut surface of the plating lead part 11 is kept to be exposed, the oxide or corrosion product may be generated at the cut surface. However, since the upper surface of the tip end of the plating lead part 11 is covered by the film member 13, the oxide or corrosion product generated at the cut surface does not reach the terminal contact part 9 without moving over the protection layer, that is, the film member 13. Thus, even when the film member 13 is stuck only on the upper surface of the tip end of the plating lead part 11 in this manner, since the film member can prevent the movement of the oxide or corrosion product, this embodiment can attain the effects of suppressing the occurrence of the defective continuity and the increase of contact resistance at the terminal contact part 9.

Further, in this embodiment, since the film member 13 capable of holding a constant shape is employed, as shown in Fig. 6, the film member 13 may be stuck so as to protrude toward the cut surface from the upper surface of the tip end of the plating lead part 11. In this case, the movement (movement to an arrow direction) of the oxide or corrosion product generated at the cut surface can be prevented more effectively. As a result, the occurrence of the defective continuity and the increase of contact resistance can be suppressed. As described above, although the embodiments of this invention are described in detail with reference to the drawings, the aforesaid embodiments are mere examples of this invention and this invention is not limited to the configurations of the aforesaid embodiments. That is, of course, this invention contains the design changes etc. not departing from the gist of this invention.

For example, although the second embodiment is explained as to the case where the resin is used as a member forming the protection layer, known adhesive may be used in place of the resin. In this case, when the adhesive in a liquid state is pasted and then hardened naturally, the sealing effect can be obtained like the case of using the resin at the cut surface of the tip end of the plating lead part 11. Further, although the third embodiment is explained as to the case of using the film member 13, other insulative material such as the resin of the second embodiment may be used. Furthermore, the material forming the protection layer is not limited to the insulative material, and the protection layer may be formed by conductive material. In brief, it is merely required to form any layer obstructing the movement at the moving path of the oxide or corrosion product.

Furthermore, the region on the upper surface of the tip end of the plating lead part where the protection layer is formed may be suitably set in view of the distance between the cut surface of the plating lead part 11 and the terminal contact part 9 and the area of the cut surface of the plating lead part 11 , for example. Although each of the embodiments is explained as to the case where the line width of the plating lead part 11 is formed to be smaller than that of the terminal contact part 9, this invention is not limited thereto and the line width of the plating lead part 11 may be formed to be same as that of the terminal contact part 9, for example.

This application is based on Japanese Patent Application (Japanese Patent Application No. 2011-147530) filed on July 1 , 2011 , the disclosure of which is incorporated herein by reference in its entirety. Industrial Applicability The present invention is useful for providing a printed board capable of suppressing the occurrence of defective continuity or the increase of contact resistance at a terminal contact part. Reference Signs List

1 printed board

3 base member

5 conductor

7 insulative resin film

9 terminal contact part

11 plating lead part

13 film member

15 adhesion layer

17 film layer

19 resin layer

Claims

1. A printed board, comprising

2. The printed board according to claim 1 , wherein

a film member having an adhesion layer formed on one major surface thereof is used as the protecting material, and

the film member is stuck to a region from a rear surface of the base member of the end portion of the plating lead part to an upper surface of the end portion of the plating lead part.

3. The printed board according to claim 1 , wherein

resin having hardenability and in a liquid or gel state is used as the protecting material, and

the resin is coated on the end portion of the plating lead part to thereby form a resin layer on a region from a rear surface of the base member of the end portion of the plating lead part to the upper surface of the end portion of the plating lead part.

4. The printed board according to claim 1 , wherein

the end portion of the plating lead part is dipped within the resin to thereby form a resin layer on a region from a rear surface of the base member of the end portion of the plating lead part to the upper surface of the end portion of the plating lead part.

5. The printed board according to claim 1 , wherein

the film member is stuck to the upper surface of the end portion of the plating lead part.