JP2007307572A - Soldering method and soldering structure for fpc - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a structure capable of soldering an FPC to an object fto be connecte with a high mechanical strength when soldering the connection end of the FPC, in which a conductive wiring pattern is embedded in an insulation film, to the object to be connected. <P>SOLUTION: The FPC soldering method comprises: a step of feeding a wiring pattern on a connection end of the FPC in a state that the insulation film is stuck to one side of its front/rear so that surface and another side is exposed; a step of turning the connection end of the FPC so that the wiring pattern is made into front side and the insulation film ois made into rear side; and a step of soldering the turned connection end while allowing the connection end to abut on the object to be connected. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for soldering a conductive wiring pattern existing in a resin coating of an FPC to another element and a soldering structure thereof.

  An FPC widely used in various electric devices is configured by embedding a conductive wiring pattern (for example, copper foil) in a resin coating made of a synthetic resin material (for example, polyimide resin).

Japanese Patent Laid-Open No. 10-335553 JP 2006-3503 A

  In order to solder the FPC to the connection object, conventionally, the resin coating is removed at the connection end portion of the FPC to expose the wiring pattern, and the exposed portion is soldered. However, this conventional method has a problem that the wiring pattern has a very weak mechanical strength, so that there is a problem of disconnection with a slight force, and the connection reliability is low or can be used only for limited applications.

  Also, in order to increase the mechanical strength of the wiring pattern part, the resin coating of the wiring pattern is removed only on the connection target side (leaving the resin coating on the back side of the connection target), and the wiring pattern is brought into contact with the connection target. When the method of soldering from the top of the resin coating was tried, there was a problem that the resin coating peeled off from the wiring pattern due to the heat of the solder and was easily disconnected. Since soldering is performed from above the resin coating, there is also a problem that the solder is not sufficiently mounted.

  An object of the present invention is to obtain a method and a structure capable of soldering an FPC to a connection object with high mechanical strength based on the above problem awareness.

  The present invention focuses on the fact that the mechanical strength can be increased by removing one of the front and back sides of the wiring pattern at the connection end of the FPC, turning it back with the resin coating side and soldering in the folded state. It was completed based on.

  In the aspect of the method of soldering the connection end of the FPC in which the conductive wiring pattern is embedded in the insulating film to the connection object, the wiring pattern of the connection end of the FPC is placed on one of the front and back sides. Supplying the other end of the FPC with the insulating film attached; the step of folding back the connection end of the FPC with the wiring pattern on the front and the insulating coating on the back; And a soldering step in contact with the substrate.

  Further, in the aspect of the structure in which the connection end portion of the FPC in which the conductive wiring pattern is embedded in the insulating film is soldered to the connection object, the connection end portion of the FPC has the insulating coating on one of the front and back sides of the wiring pattern. The other end of the FPC is exposed while the FPC is attached; the connection end of the FPC is folded with the wiring pattern on the front and the insulating coating on the back; It is characterized by being soldered to the object.

  The present invention can be applied without questioning the connection object. For example, when a shim of a piezoelectric vibrator is used as the connection object, high connection reliability with respect to the vibrating shim can be obtained.

  ADVANTAGE OF THE INVENTION According to this invention, the method and structure which can solder FPC to a connection target object with high mechanical strength can be obtained.

  FIG. 11 shows the simplest example of the FPC soldering method and soldering structure according to the present invention. The FPC 20 includes a wiring pattern 22 made of copper foil (conductor) in an insulating film 21 made of polyimide resin (insulating resin). In the FPC 20, at one end of the electrical connection, one insulating coating 21 on the front and back of the wiring pattern 22 is removed, and the other is left. Let the exposed part of the wiring pattern 22 be a connection end 22a. Such partial removal of the insulating coating 21 can be performed when the FPC 20 is manufactured.

  When the connection end 22a of the FPC 20 is soldered to the connection object 111a, the connection end 22a is turned upside down and the insulating coating 21 is turned back. The folded connection end 22 a ′ has its free end abutted against the connection object 111 a and is soldered by the solder 25. The solder 25 is sized to wrap around the entire folded connection end 22a '.

  When the end portion of the FPC 20 with the insulating coating 21 remaining in this way is bent with the insulating coating 21 inside, and the connection end portion 22a is soldered, the mechanical strength of the connection end portion 22a is not impaired.

  In FIG. 11, the free end portion of the folded connection end portion 22a ′ is brought into contact with the connection object 111a. However, as shown in FIG. 12, the free end portion may be positioned on the side away from the connection object 111a. Good.

Next, an embodiment in which the present invention is applied to a feeding structure of a piezoelectric vibrator of a piezoelectric pump will be described.
FIG. 1 schematically shows an example of a conceptual configuration of a piezoelectric pump. The housing 10 includes an upper housing 10a and a lower housing 10b, and a piezoelectric vibrator 11 is tightly supported between the upper housing 10a and the lower housing 10b. Although the thickness of the piezoelectric vibrator 11 is exaggerated, the actual thickness is less than 1.5 mm. The upper housing 10a has a peripheral fixing portion 13 that fixes the periphery of the piezoelectric vibrator 11 with a closed curve, and the piezoelectric vibrator 11 is liquid-tightly connected to the lower housing 10b via the peripheral fixing portion 13 and the O-ring 19. Pinch. The inside of the peripheral edge fixing portion 13 and the O-ring 19 is a concave portion that forms the variable volume chamber 12 with the piezoelectric vibrator 11.

  The upper housing 10a has an inlet port 14A and an outlet port 14B for cooling water (liquid). The inlet port 14A communicates with the inlet side liquid reservoir chamber 15A, and the outlet port 14B is connected to the outlet side liquid reservoir chamber 15B. Communicating with Partition walls 16A and 16B are located between the inlet side liquid reservoir chamber 15A and the variable volume chamber 12, and between the outlet side liquid reservoir chamber 15B and the variable volume chamber 12, respectively. Stop valves) 17A and 17B are provided. The umbrella 17A allows fluid flow from the inlet port 14A (inlet side reservoir chamber 15A) to the variable volume chamber 12 and not vice versa, and the umbrella 17B passes from the variable volume chamber 12 to the outlet port 14B (outlet). This is a check valve that allows a fluid flow to the side liquid reservoir 15B) but does not allow the opposite fluid flow.

  In the above-described piezoelectric pump, when the piezoelectric vibrator 11 is elastically deformed in the forward and reverse directions, the umbrella 17A is opened and the umbrella 17B is closed in the stroke in which the volume of the variable volume chamber 12 is expanded. The liquid flows into the variable volume chamber 12 from 15A). On the other hand, in the stroke in which the volume of the variable volume chamber 12 is reduced, the umbrella 17B is opened and the umbrella 17A is closed, so that the liquid flows out from the variable volume chamber 12 to the outlet port 14B (outlet side liquid reservoir chamber 15B). Therefore, the pump action can be obtained by elastically deforming (vibrating) the piezoelectric vibrator 11 continuously in the forward and reverse directions.

  As schematically shown in FIG. 2, the piezoelectric vibrator 11 includes a circular shim 111 at the center, a circular piezoelectric body 112 formed on the front and back of the shim 111, and annular spacers positioned on the front and back of the shim 111. The insulating ring 113, the front and back piezoelectric bodies 112, and the insulating protective film 114 that covers the surface of the spacer insulating ring 113 are provided.

  The shim 111 is made of a conductive metal thin plate material, for example, a stainless steel thin plate having a thickness of about 0.2 mm, and includes a wiring connection projection 111a projecting in the radial direction and a feeding line support projection 111b for piezoelectric body. .

The piezoelectric body 112 is made of, for example, PZT (Pb (Zr, Ti) O ₃ ) having a thickness of about 0.3 mm, and is polarized in the front and back directions. This polarization process is performed in the same direction in the pair of piezoelectric bodies 112 positioned on the front and back of the shim 111. That is, in FIG. 2, when the polarization direction of the pair of piezoelectric bodies 112 is represented by arrows a or b, polarization processing in the same direction is performed in the thickness direction of the shim 111. The surfaces of the pair of piezoelectric bodies 112 on the shim 111 side are bonded so as to be fully conductive with the shim 111, and a film electrode is formed on the entire exposed surface opposite to the shim 111 side. The film electrode can be formed, for example, by printing (screen firing) a conductive paste (gold paste). The film-like electrode can also be formed on the surface of the piezoelectric body 112 on the shim 111 side, and if this film-like electrode is used, the entire surface can be easily conducted. The material and forming method of the membrane electrode are well known.

  The above-described piezoelectric vibrator 11 is known as a bimorph type piezoelectric vibrator. When an alternating electric field is applied using the shim 111 as one common electrode and the exposed surface of the pair of piezoelectric bodies 112 as the other common electrode, both sides are Repeatedly (vibrates) one of the two stretches and the other shrinks.

  As shown in FIG. 3 to FIG. 7, a power supply FPC 20 as a power supply means for the piezoelectric vibrator 11 includes a shim power supply line made of copper foil (conductor) in an insulating film 21 made of polyimide resin (insulating resin). A wiring pattern) 22 and a piezoelectric power supply line (wiring pattern) 23 are embedded. The power supply FPC 20 includes a shim connection portion 20c and a piezoelectric body connection portion 20d separated by a dividing groove 20b at one end of the linear portion 20a (a connection end with the piezoelectric vibrator 11). The shim power supply line 22 and the piezoelectric power supply line 23 extend in parallel in the linear part 20a, and the shim power supply line 22 extends from the linear part 20a into the shim connection part 20c, and at the tip thereof. Constitutes a shim connection end portion 22a from which one of the front and back insulating coatings 21 (the surface opposite to the surface facing the wiring connection protrusion 111a) is removed (see FIG. 5). On the other hand, the piezoelectric connecting portion 20d has an inclined branch portion 20e that is inclined with respect to the extending direction of the power supply FPC 20 and extends to the left and right (both sides). The piezoelectric power supply line 23 includes a linear portion 20a and a piezoelectric portion. The body connecting portion 20d is further extended into the inclined branching portion 20e, and a pair of piezoelectric connecting end portions 23a formed by removing one of the front and back insulating coatings 21 are provided at both ends of the inclined branching portion 20e. (See FIG. 4). As shown in FIGS. 3 and 6, the shim connection end 22 a and the piezoelectric body connection end 23 a are exposed on the same surface in the free (planar) state of the power feeding FPC 20. 3 and 6, the shim connection end 22 a and the piezoelectric body connection end 23 a facing the front are indicated by solid-line hatching, and the shim connection end 22 a facing the back (downward) is indicated by broken-line hatching. Further, as shown in FIG. 3, power supply terminals 22 b and 23 b are formed at the other end of the power supply FPC 20 so as to expose the shim power supply line 22 and the piezoelectric power supply line 23.

  The conduction connection of the power supply FPC 20 to the piezoelectric vibrator 11 is performed as follows. The FPC soldering method (structure) according to the present invention is applied to soldering of the shim connecting end 22a to the shim 111. As shown in FIGS. 6 and 7, the shim connection end portion 22a is folded back with the insulating coating 21 inside, and the shim connection end portion 22a is brought into contact with the wiring connection projection 111a in the folded state and solder 25 (FIG. 7). Solder with. In this way, when the shim connection end 22a is soldered in a state where the insulation coating 21 is turned inside, the mechanical strength of the end of the shim power supply line 22 can be increased. On the other hand, the pair of piezoelectric connecting end portions 23a is bent (turned back) into the U-shaped inclined branch portion 20e with the pair of piezoelectric connecting end portions 23a inside, and the conductive adhesive 29 (FIG. 7) is interposed therebetween. Adhere to the front and back piezoelectric bodies 112. In the U-shaped bent portion of the inclined branch portion 20e, the piezoelectric power supply line supporting protrusion 111b of the shim 111 is located, and the excessive deformation of the inclined branch portion 20e is prevented. The insulating protective film 114 is attached so as to cover the inclined branching portion 20e of the power feeding FPC 20 across the piezoelectric body 112 and the insulating spacer ring 113 after the piezoelectric connecting end portion 23a is bonded. The power supply terminals 22b and 23b are connected to an alternating current power supply circuit.

  A pair of positioning recesses 24 are formed on the insulating coating 21 of the power supply FPC 20 so as to be positioned at the branch portion between the shim connection portion 20c and the piezoelectric body connection portion 20d. In addition, as shown in FIGS. 8 and 10, the housing 10 (lower housing 10 b) has a positioning convex portion 27 that engages with the pair of positioning concave portions 24 so as to face each other in the storage groove 26 that stores the power supply FPC 20. Is formed. FIG. 10 is a more specific example of the piezoelectric pump schematically shown in FIG. 1, and the same components as those of FIG. 1 are denoted by the same reference numerals. The O-ring in FIG. 10 is a plane D-shaped deformed O-ring 12X, and the piezoelectric body connecting end portion 23a is electrically connected to the piezoelectric vibrator 11 so as to be located outside the deformed O-ring 12X.

  The positioning concave portion 24 of the power feeding FPC 20 and the positioning convex portion 27 of the lower housing 10b are connected to the piezoelectric vibrator 11 in which the shim connection end portion 22a is connected to the wiring connection projection 111a and the piezoelectric body connection end portion 23a is connected to the piezoelectric body 112. In the state set in the piezoelectric pump, the power FPC 20 is given a sag F more than the free state. FIG. 9A schematically shows a slack (slack) F given to the power supply FPC 20 by the positioning concave portion 24 and the positioning convex portion 27 in an exaggerated manner. In this way, when the slack F larger than the free (flat plate) state drawn by the chain line is given to the power supply FPC 20, even if the vibration of the piezoelectric vibrator 11 is repeated over a long period of time, the shim power supply line 22 and the piezoelectric material supply There is no possibility that the electric wire 23 is disconnected. In particular, since the shim power supply line 22 is provided in the linear shim connection portion 20c, there is a high risk of disconnection due to vibration, and therefore the effect of preventing disconnection due to sagging is high.

  Further, in the illustrated embodiment, the insulating coating 21 of the shim connection portion 20c of the power supply FPC 20 is positioned closer to the piezoelectric vibrator 11 than the pair of positioning recesses 24, and the narrow portion 20f that facilitates elastic deformation (FIG. 3). , FIG. 6) is formed. Further, the shim power supply line 22 in the narrow part 20f is a narrow power supply line 22 'narrower than the other parts, and is easily elastically deformed. Note that the slack (slack) F in FIG. 9A may be provided by a bent portion 30 formed by forming a crease in the narrow portion 20f as shown in FIG. 9B.

  In the illustrated embodiment, the surface of the shim connection end portion 22a is exposed on the same surface as the surface of the piezoelectric body connection end portion 23a (FIGS. 3 and 6), and the wiring is performed with the insulating coating 21 turned inward. Although soldered to the lower surface of the connection protrusion 111a, the front and back surfaces of the shim connection end portion 22a are reversed, and the surface of the shim connection end portion 22a is exposed on the same surface as the back surface of the piezoelectric body connection end portion 23a. There may be.

  In the above embodiment, the pair of piezoelectric connecting end portions 23a are conductively connected to the front and back piezoelectric bodies 102 via the conductive adhesive 29. However, the present invention is also applied to the conductive connection of the piezoelectric connecting end portions 23a. Is possible. Further, FIGS. 1 to 10 show the FPC soldering method (structure) according to the present invention applied to a power feeding structure for the shim 111 of the piezoelectric pump. However, the present invention generally employs the FPC soldering method (structure). Can be widely applied.

It is a schematic diagram which shows an example of a conceptual structure of the piezoelectric pump which applies the soldering method (structure) of FPC of this invention. It is a disassembled perspective view of the piezoelectric vibrator of the piezoelectric pump of FIG. It is a plane development view showing one embodiment of electric power feeding FPC to a piezoelectric vibrator. It is sectional drawing which follows the IV-IV line of FIG. It is sectional drawing which follows the VV line of FIG. FIG. 6 is a perspective view of a main part before and after electrically connecting the power supply FPC of FIGS. 3 to 5 to a piezoelectric vibrator. It is sectional drawing of the state which electrically connected FPC to the piezoelectric vibrator. It is a perspective view of the principal part of the housing which accommodates the said electric power feeding FPC. It is a schematic diagram explaining the slack of the electric power feeding FPC accommodated in the housing. It is a perspective view which shows the specific structural example of the piezoelectric pump to which the electric power feeding structure of FPC by this invention is applied. It is process drawing which shows 1st Embodiment of the soldering method (structure) of FPC by this invention. It is sectional drawing which shows 2nd Embodiment of the soldering method (structure) of FPC by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Housing 11 Piezoelectric vibrator 12 Variable volume chamber 13 Perimeter fixing | fixed part (fixing member)
111 Shim 111a Wiring connection projection 111b Piezoelectric power supply line support projection 112 Piezoelectric body 113 Insulating spacer ring 114 Insulating protective film 20 Power feeding FPC
20a Linear part 20b Dividing groove 20c Shim connection part 20d Piezoelectric connection part 20e Inclined branch part 20f Narrow part 21 Insulation coating 22 Shim power supply line (wiring pattern)
22a Shim connection end 22 ′ Narrow feed line 22b 23b Feed terminal 23 Piezoelectric feed line (wiring pattern)
23a Piezoelectric connection end 24 Positioning recess 25 Solder 26 Storage groove 27 Positioning projection 29 Conductive adhesive 30 Bending portion F Slack

Claims (4)

A method of soldering a connection end portion of an FPC in which a conductive wiring pattern is embedded in an insulating film to a connection object,
Supplying the wiring pattern of the connection end of the FPC with the other exposed while the insulating film is attached to one of the front and back sides;
Folding back the connection end of the FPC with the wiring pattern on the front and the insulating coating on the back; and soldering the free end of the folded connection end against the connection object;
A method for soldering an FPC, comprising: 2. The FPC soldering method according to claim 1, wherein the connection object is a shim of a piezoelectric vibrator. A structure in which a connecting end portion of an FPC in which a conductive wiring pattern is embedded in an insulating film is soldered to an object to be connected,
The connection end of the FPC is exposed with the insulating film attached to one of the front and back sides of the wiring pattern;
The connection end of the FPC is folded with the wiring pattern on the front and the insulating coating on the back; and the folded connection end is covered with solder and soldered to the connection object;
FPC soldering structure characterized by 4. The FPC soldering structure according to claim 3, wherein the connection object is a shim of a piezoelectric vibrator.

Images