JP2001024299A - Connector of flexible printed-circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reliable connector where retention and contact force are not reduced even in severe usage environment. SOLUTION: An elastic member 4 is retained by a holder 13, and is nearly cylindrically formed along the widtwise direction of a flexible printed-circuit board (FPC) 2. At one part of the cylinder side surface of the elastic member 4, a defective part 40 where a side wall does not exist along a Y-axis direction is provided. On the upper surface of a circuit board 3, a wiring layer 30 is formed. At the connection part between the circuit board 3 and the FPC 2, an anisotropic conductive material 5 is provided between both of them. The elastic member 4 is positioned at the upper part of the FPC 2, the FPC 2 is pressed to the circuit board 3 by the press force of the elastic member 4 for retaining. In this state, a contact can be rotated and displaced in the elastic member 4, and stable electric contact between a wiring film 21 and the wiring layer 30 is achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a connector between a flexible printed circuit board and a circuit board. In particular,
It is suitable for use in automobiles with a lot of vibration and a wide temperature range. For example, it is used for connecting a flexible printed board provided with a pressure-sensitive sensor for detecting the weight of an occupant in a vehicle occupant protection device to a circuit board.

[0002]

2. Description of the Related Art Conventionally, an anisotropic conductive material has been used to electrically connect a wiring film formed on a flexible printed circuit board (hereinafter abbreviated as FPC) to a wiring layer formed on a circuit board. There is something. The anisotropic conductive material is obtained by mixing conductive particles into a resin-based adhesive. Since conductive particles exist between a pair of contacts sandwiching the anisotropic conductive material, current flows between the contacts, but conductive particles are discretely provided in the plane direction of the anisotropic conductive material. Therefore, no current flows in the lateral direction. Utilizing this property, a plurality of wiring films on a flexible printed circuit board and a plurality of corresponding wiring layers on a circuit board are electrically connected to each other while being insulated and separated from other wiring layers. is there.

[0003] As a method not using an anisotropic conductive material,
As shown in FIG. 8, a wiring layer 73 formed on a circuit board 71 and a wiring film 74 formed on a flexible printed board 72 are connected to each other by using a cylindrical clip ring 70 having a cross section of “C” shape. There is known a device that makes a mechanical and electrical contact with an elastic force.

[0004]

However, simply,
The method of obtaining electrical contact using an anisotropic conductive material involves a change in the physical properties and deterioration of the adhesive of the anisotropic conductive material when the use environment temperature is high, such as 100 ° C. or higher, or when used for a long time. As a result, the bonding strength was reduced. As a result of the lowering of the bonding force, there is a problem that poor electrical contact occurs or the flexible printed circuit board cannot sufficiently withstand the tensile force, and the bonded portion is separated. For this reason, in a severe use environment such as a wide temperature range of the use environment and a large amount of vibration, it has not been possible to obtain an electrical contact that ensures reliability for a long period of time.

As shown in FIG. 8, a method of mechanically obtaining electrical contact by the elastic force of a clip spring 70 is as follows.
It is difficult to assemble the flexible printed board 72 and the circuit board 71 with the clip spring 70, and there is a problem that workability is poor. Also, the flexible printed board 72 and the circuit board 71 are clipped by the clip spring 70.
Because of this, the arrangement direction of the flexible printed circuit board 72 and the circuit board 71 is limited to one direction where the clip spring 70 is open. Further, since the cross section of the clip spring 70 cannot be increased, the spring constant increases, and the clip spring 70 cannot be displaced following the creep compression of the flexible printed circuit board 72 and the circuit board 71, and the holding force and the contact force decrease. There is a problem. Furthermore, since the flexible printed circuit board 72 and the circuit board 71 are sandwiched between both edges of the clip spring 70, a shear force acts when vibration is applied, and the flexible printed circuit board 72 may be damaged.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a highly reliable connector which does not reduce holding force and contact force even in a severe use environment. Another object is to facilitate assembling a flexible printed circuit board to a circuit board. Still another object is to provide a structure in which the holding force does not decrease even when vibration is applied. Still another object is to improve the durability against vibration by providing a structure in which no shear force acts on the flexible printed circuit board even when vibration is applied.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a connector for connecting a flexible printed board having a wiring film formed on a resin substrate to a wiring layer of a circuit board. An anisotropic conductive material, which is disposed between the wiring film of the printed board and the wiring layer of the circuit board, and which conducts in the thickness direction but does not conduct in the surface direction, and is disposed. And an elastic member for pressing the flexible printed board against the circuit board at the position. The flexible printed board is firmly held on the circuit board by the pressing force of the elastic member, and conduction between the wiring film of the flexible printed board and the wiring layer of the circuit board is obtained by the anisotropic conductive material. Since an anisotropic conductive material is used, there is no need to provide an insulating gap between each wiring film and between each wiring layer, and the assembling becomes easy. Since the flexible printed board is held on the circuit board by the pressing force of the elastic member, there is an effect that the flexible printed board is strong against vibration.

Another aspect of the present invention is a connector for connecting a flexible printed board having a wiring film formed on a resin substrate to a wiring layer of a circuit board, wherein the wiring film of the flexible printed board and the wiring layer of the circuit board are in contact with each other. The heat seal member that covers the flexible printed circuit board from above and holds the flexible printed circuit board to the circuit board in a state where the wiring film is in contact with the wiring layer of the flexible printed circuit board and the wiring layer of the circuit board. And an elastic member for pressing the flexible printed board against the circuit board. Since the flexible printed circuit board is held on the circuit board by the heat sealing member, the assembly is performed by the elastic member, so that the alignment between the wiring film and the wiring layer is prevented from being displaced during the assembly by the elastic member, and the assembly is easy. Becomes Further, since the flexible printed board is held on the circuit board by the pressing force of the elastic member, there is an effect that the flexible printed board is strong against vibration.

In another aspect of the invention, the elastic member has a width along a width direction of the flexible printed circuit board, and a contact portion with the flexible printed circuit board in a cross section perpendicular to the width direction has an arc shape. That is. By making the contact part arc-shaped, the holding force of the flexible printed circuit board to the circuit board is stabilized, and the shearing force acts on the flexible printed circuit board even in the longitudinal direction of the flexible printed circuit board in the insertion direction and the detaching direction. Not so, resulting in a highly reliable connector. In addition, because of the arc shape, a minute rotational displacement can be made in the insertion direction and the removal direction of the flexible printed circuit board. That is, even if the flexible printed circuit board is slightly displaced with respect to the anisotropic conductive material, a follow-up displacement is possible, so that a stable contact is secured without lowering the pressing force, and the vibration resistance is improved.

According to another aspect of the present invention, the elastic member has a cylindrical shape having an axis in the width direction of the flexible printed circuit board. Therefore, as described above, stability of holding force, vibration resistance, and ease of assembly are improved. , The shearing force is suppressed.

According to another aspect of the present invention, the elastic member has a defective portion having no side surface along the axial direction, so that the spring constant can be reduced, the displacement corresponding to the plastic deformation of the flexible printed circuit board can be achieved, and the stable elasticity can be obtained. As a result, the reliability can be improved. According to another invention, since the defective portion of the elastic member is located forward of the direction of insertion of the flexible printed board from the contact portion with the flexible printed board, the force acts in the direction in which the flexible printed board is inserted. In this case, since the elastic member is deformed so as to have a small diameter, the displacement in this direction is relatively easy. Conversely, when a force acts in the direction of detaching the flexible printed circuit board from the connector, the elastic member is deformed so as to have a larger diameter, so that the pressing force increases, and the detachment of the flexible printed circuit board is prevented. Works. As a result, a stable holding force can be obtained, and stable electrical contact with respect to vibration and external force can be realized, thereby improving the reliability of the connector.

According to another aspect of the present invention, since the elastic member is formed of a leaf spring, a stable elastic force can be applied to the flexible printed circuit board, so that reliability can be improved. According to another invention, the elastic member can be displaced around an axis along the width direction of the flexible printed circuit board, so that the vibration resistance is improved. According to another invention, a circuit board has a wiring layer formed on both sides, a flexible printed board includes a pair of upper and lower sides each having a wiring film formed on an inner surface, and the elastic member has a pair of elastic members on both sides of the circuit board on the circuit board side. It is characterized by comprising a pair for pressing the flexible printed circuit board. Therefore, since the electrical contact portions are formed on both sides of the circuit board, the wiring mounting density can be improved, and the size of the connector can be reduced.

Another aspect of the present invention has a case in which a circuit board is disposed, a flexible printed board is inserted therein, and an elastic member is supported, so that the elastic member can be easily held, and the flexible printed board can be mounted on the circuit board. It will be easier. According to another invention, since the elastic member is made of a resin formed integrally with the case, the manufacture of the connector is facilitated. According to another invention, since the flexible printed circuit board is fixed to the case before the contact portion with the elastic member, even if a large force acts on the flexible printed circuit board, this force does not act on the electric contact portion. , And stable electrical contact is possible. Further, in another invention, the connector is used in an automobile. This connector is suitable for use in an automobile that has a wide operating temperature range, large vibration, and a severe usage environment.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on specific embodiments. The present invention is not limited to the following embodiments. (First Embodiment) FIGS. 1, 2 and 3 show a connector 10 according to a first embodiment of the present invention. FIG. 1 is a cross-sectional view showing a connection state between the FPC 2 and the circuit board 1, FIG. 2 is a cross-sectional view along the width direction of the FPC 2 showing a structure of a contact portion, and FIG. It is a perspective view.

As shown in FIG. 2, the FPC 2 comprises a resin film 22 made of PET (polyethylene terephthalate) or PI (polyimide) and a wiring film 2 formed on the lower surface thereof.
1 and 1. As a method of forming the FPC 2,
A metal foil such as copper is formed on the resin film 22 and the metal foil is etched into a predetermined shape to form the wiring film 21.
Or forming the wiring film 21 by printing a conductive ink on the resin film 22. The FPC 2 detects, for example, whether or not there is an occupant on a seat, or a pressure-sensitive switch for detecting pressure based on weight distribution or total gravity on the seat when activating an airbag device of an automobile. Used to derive signals to the outside.

The connector 10 has an upper case 11 and a lower case 12. The upper case 11 and the lower case 12
The circuit board 1 is disposed in the internal space defined by the above. In this embodiment, the connector 10 is understood as an electronic device including the entire circuit board 1. However, the connector of the present invention may be a connection mechanism that does not include a case. Further, a case having only a connection portion of the FPC 2, a connection portion of the circuit board 3, and a connection mechanism may be provided.

The FPC 2 is provided from the outside to the inside of the case so as to be sandwiched between the upper case 11 and the lower case 12. A holder 13 formed in a groove shape is formed in the upper case 11, and the elastic member 4 is held by the holder 13. The elastic member 4 extends in the width direction of the FPC 2, that is,
It is formed in a substantially cylindrical shape along the Y-axis direction in FIG. As shown in FIG. 1, a defective portion 40 having no side wall along the Y-axis direction is provided on a part of the side surface of the cylinder of the elastic member 4. This defective portion 40 is F
It is located forward in the insertion direction (x direction) of PC2.

A copper film, a silver-based conductor,
Alternatively, the wiring layer 30 made of a metal film such as an aluminum film is formed. At the connection between the circuit board 3 and the FPC 2, an anisotropic conductive material 5 is disposed between the two. The anisotropic conductive material 5 is obtained by dispersing conductive particles such as nickel (Ni) in a resin adhesive or an adhesive sheet. As shown in FIG. 2, since the conductive particles 50 exist between the wiring film 21 and the wiring layer 30, a current flows in the thickness direction. However, in the planar direction of the anisotropic conductive material 5, an electric current does not flow because the insulating base material 51 exists between the adjacent conductive particles 50 and the conductive particles 50 are not continuous.

The elastic member 4 is located above the FPC 2, and the FPC 2 is pressed and held by the circuit board 3 by the pressing force of the elastic member 4. In this state, stable electrical contact between the wiring film 21 and the wiring layer 30 is realized.

The connector 10 is assembled as follows. The circuit board 3 is disposed on the lower case 12, and the anisotropic conductive material 5 is disposed on the connection portion on the upper surface. Next, the FPC 2 is bonded to the circuit board 3 with the anisotropic conductive material 5 in a state where the wiring layer 30 of the circuit board 3 and the wiring film 21 of the FPC 2 are aligned. Next, the upper case 11 having the holder 13 holding the elastic member 4 is combined with the lower case 12 from above,
The upper case 11 is connected to the lower case 1 by a lock mechanism (not shown).
Lock to 2.

In this state, the contact portion A of the elastic member 4
Is displaced upward (−z-axis direction) due to the presence of the defective portion 40, and gives a pressing force to the FPC 2 as a reaction. Due to the presence of the deficient portion 40, the spring constant is reduced, and the elastic following can be performed even if there is a relatively large displacement. Therefore, even if the FPC 2 and the circuit board 3 are plastically deformed by long-term pressing force, the elastic member 4 can press the FPC 2 against the circuit board 3 without attenuating the pressing force. As a result, the electrical contact between the wiring film 21 and the wiring layer 30 is stabilized for a long period of time.

In this state, the insertion direction (x
When a force acts in a detaching direction (−x direction) opposite to the direction (−x direction), the elastic member 4 receives a slight rotational displacement in the θ direction due to the presence of the defective portion 40. This rotational displacement acts to further increase the pressing force of the FPC 2 against the circuit board 3.
Therefore, the FPC 2 is effectively prevented from being detached from the circuit board 3. When a force acts on the FPC 2 in the insertion direction (x direction), the elastic member 4 is
Receives a slight displacement in the θ direction. Since this displacement acts to reduce the pressing force of the elastic member 4, the FPC 2 is more easily displaced in the X-axis direction, and the holding force of the contact portion increases. Due to such an effect, even if vibration is applied, FP
C2 is reliably prevented from detaching from the circuit board 3, and a highly reliable connector is obtained.

Second Embodiment Next, a connector 110 according to a second embodiment will be described. In FIG. 4, the lower case 1
FPC2 on projections 121, 122, 123 formed on
And the FPC 2 is mechanically fixed before the FPC 2 is held by the elastic member 4. At this time, the FP between the contact portion A with the elastic member 4 and the holding portion of the projection 121
C2 is loosely arranged. Thereby, FPC2
Even if a large force acts in the release direction (-x direction),
Separation of C2 from the circuit board 3 can be reliably prevented. Further, even if vibration is applied due to the above-mentioned slack, the FPC 2 follows the minute displacement due to the elastic force of the elastic member 4 and is displaced, so that the electrical contact of the contact portion is ensured.

(Third Embodiment) Next, a connector 120 according to a third embodiment will be described. In FIG. 5, the circuit board 3
Wiring layers 30a and 30b are formed on both surfaces of the circuit board 3, and a pair of FPCs 2a and 2b are arranged on both surfaces of the circuit board 3 to face each other. The pair of FPCs 2a and 2b are formed, for example, with wiring films 21a and 21b for electrically wiring the respective contacts of the pressure-sensitive sensor in which opposed contacts are formed on a pair of upper and lower resin films. Above the circuit board 3, a substantially cylindrical elastic member 4 a having a cutout 40 is held by a holder 13 a formed on the upper case 11, and below the circuit board 3, an elastic member 4 b having the same shape is held below. It is held by a holder 13b formed in the case 12.

In this manner, the wiring films 21a and 21b of the FPC and the wiring layers 21a and 21b on the circuit board can be electrically connected on the upper and lower sides of the circuit board 3, respectively. The assembling method and the operation and effect of the connector 120 are the same as those of the first and second embodiments. In this way,
A connector having an improved wiring mounting density can be obtained.

(Fourth Embodiment) Next, a connector 130 according to a fourth embodiment will be described. In FIG. 6, the elastic member 4
5 is formed of resin integrally with the upper case 11. The elastic member 45 has a corrugated foot 46 that extends in a plane in the width direction (y direction) of the FPC 2 and a contact portion 47 that contacts the FPC 2. Due to the waveform of the foot 46, the FPC2
Can be applied downward (in the z direction). Further, even if a force in the insertion / removal direction (x, -x direction) of the FPC 2 acts, the contact portion 47 can easily follow and displace. As a result, stable electrical contact can be obtained even when vibration is applied.

(Fifth Embodiment) Next, a connector according to a fifth embodiment will be described. In this embodiment, as shown in FIG.
After the wiring layer 30 of the circuit board 3 and the wiring film 21 of the FPC 2 are positioned so as to be in contact with each other, the connection portion is covered with a heat seal 6 and heated to fix the heat seal 6 to the circuit board 3. . In this embodiment, the wiring film 21 is in contact with the wiring layer 30 without using an anisotropic conductive material. In this manner, the FPC 2 and the circuit board 3 are connected to each other and fixed to the lower case 12, and the upper case 11 holding the elastic member 4 as shown in FIG. is there. The elastic member 4 has the same effect as the above embodiment. In addition, heat seal 6 is used for FPC2.
And the circuit board 3 are fixed and disposed in the case, so that there is no displacement between the wiring film 21 and the wiring layer 30,
Assembly becomes easy.

(Modification) The shape of the elastic member 4 is preferably substantially cylindrical, but is not limited to this. For example, it may be constituted by a number of strips bent in an arc shape from the base surface. That is, the teeth may be formed in a comb shape, the teeth may be bent in an arc shape, and the teeth may be pressed. It is desirable that the defective portion 40 be formed over the entire length along the axial direction of the cylindrical shape, but the present invention is not limited to this. For example, a portion may be formed as a window along the axial direction. The spring constant can be adjusted by the size of this window area. The assembling was performed by disposing the FPC and the substrate in the lower case, and then covering the upper case.However, the FPC and the substrate were connected to each other through an anisotropic conductive material or a window provided in a case in which an elastic member was held. A component bonded by heat sealing may be inserted and brought into contact with the elastic member to apply a pressing force to the FPC. In the first embodiment, the elastic member is formed of a metal material.
It may be resin or rubber.

[Brief description of the drawings]

FIG. 1 is a sectional view of a connector according to a first specific example of the present invention.

FIG. 2 is a sectional view of a connection portion of the connector according to the first embodiment.

FIG. 3 is a perspective view of an upper case of the connector according to the first embodiment;

FIG. 4 is a perspective view showing a configuration of a connector according to a second embodiment.

FIG. 5 is a sectional view of a connector according to a third embodiment.

FIG. 6 is a sectional view of a connector according to a fourth embodiment.

FIG. 7 is a plan view showing a connection structure between an FPC and a circuit board in a connector according to a fifth embodiment.

FIG. 8 is a perspective view showing the structure of a conventional connector.

[Description of Signs] 2 ... Flexible printed circuit board (FPC) 3 ... Circuit board 4, 45 ... Elastic member 5 ... Anisotropic conductive material 6 ... Heat seal 10, 110, 120, 130 ... Connector 21 ... Wiring film 30 ... Wiring Layer 11: Upper case 12: Lower case 13: Holder

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5E077 BB31 BB32 CC02 DD17 GG12 GG28 JJ24 JJ25 5E344 AA02 AA22 BB02 BB04 CC03 CC23 CD04 CD18 DD09 EE01 EE11

Claims (13)

[Claims] 1. A connector for connecting a flexible printed board having a wiring film formed on a resin substrate to a wiring layer of a circuit board, wherein a connector is provided between the wiring film of the flexible printed board and the wiring layer of the circuit board. And an anisotropic conductive material that conducts in the thickness direction but does not conduct in the surface direction, and presses the flexible printed board against the circuit board at a position where the anisotropic conductive material is disposed. A connector for a flexible printed circuit board comprising an elastic member. 2. A connector for connecting a flexible printed board having a wiring film formed on a resin substrate to a wiring layer of a circuit board, wherein the wiring film of the flexible printed board contacts the wiring layer of the circuit board. A heat sealing member that covers the flexible printed circuit board from above and holds the flexible printed circuit board on the circuit board in a state where the flexible printed circuit board is aligned, and the wiring film of the flexible printed circuit board and the wiring layer of the circuit board. An elastic member for pressing the flexible printed circuit board against the circuit board at a position where the connector contacts the flexible printed circuit board. 3. The elastic member has a width along a width direction of the flexible printed circuit board, and a contact portion with the flexible printed circuit board in a cross-sectional shape perpendicular to the width direction is arc-shaped. The flexible printed circuit board connector according to claim 1 or 2, wherein 4. The connector for a flexible printed circuit board according to claim 1, wherein the elastic member has a cylindrical shape having an axis in a width direction of the flexible printed circuit board. . 5. The flexible printed circuit board connector according to claim 4, wherein the elastic member has a defective portion having no side surface along the axial direction. 6. The flexible printed circuit board according to claim 5, wherein the defective portion of the elastic member is located forward of a direction of insertion of the flexible printed circuit board from a contact portion with the flexible printed circuit board. Connectors. 7. The flexible printed circuit board connector according to claim 1, wherein the elastic member is formed of a leaf spring. 8. The flexible printed circuit board according to claim 1, wherein the elastic member is displaceable around an axis along a width direction of the flexible printed circuit board. Connectors. 9. The circuit board has the wiring layers formed on both sides thereof, the flexible printed board comprises a pair of upper and lower sides each having the wiring film formed on an inner surface thereof, and the elastic member is formed on both sides of the circuit board. The flexible printed circuit board connector according to any one of claims 1 to 9, comprising a pair configured to press the pair of flexible printed circuit boards against the circuit board. 10. The circuit according to claim 1, further comprising a case on which the circuit board is arranged, the flexible printed circuit board is inserted, and the elastic member is supported. Flexible printed circuit board connector. 11. The flexible printed circuit board connector according to claim 1, wherein the elastic member is made of a resin formed integrally with the case. 12. The flexible print according to claim 1, wherein the flexible printed circuit board is fixed to the case before a contact portion with the elastic member. Board connector. 13. The connector according to claim 1, wherein the connector is used in an automobile.