WO1998013206A1 - Thermal head - Google Patents

Abstract

A thermal head for a thermal printer. Since a flexible wiring board (4) is bent in the vicinity of a soldered joint (8) between a common electrode (23) for a heater (2) and the flexible wiring board (4), the soldered joint is prevented from being separated by virtue of the resilient force, expecially, at ends thereof, realizing a reliable thermal head. Provided are a central conductor pattern (42b) on which a central copper foil removed portion (42d) is formed by removing copper foil bonded to a base film (41) and both-end conductor patterns (42c) on which both-end copper foil removed portions (42f) having a width greater than that of the central copper foil removed portion are formed at both ends of the central copper foil removed portion. The both-end conductor pattern portions (42c) are low in the ratio of copper foil and in the rigidity, and therefore it is possible to prevent the soldered portion from being separated at the ends thereof.

Description

 Description Service-Manole Head Technical Field

 The present invention relates to a thermal head for performing thermal recording by arranging a plurality of heating elements in a straight line, and more specifically, a flexible head for supplying a current to a common electrode connected to a plurality of heating elements arranged in a straight line. The present invention relates to a thermal head having a wiring board, wherein one end of a conductive layer of the flexible wiring board is soldered to a common electrode. Background art

 The thermal head is used for a thermal type printing device such as a thermal type or a thermal transfer type. Such a printing device is widely used as, for example, a computer or a facsimile output device.

 The thermal head has a heating element provided on the surface of a ceramic substrate, the heating element has a plurality of heating elements arranged in a line and a common electrode, and one terminal of the plurality of heating elements is connected to the common electrode. ing. A flexible wiring board in which a conductive layer, for example, copper foil, is adhered to the common electrode on the flexible insulating film is joined by soldering. The other terminal of the heating element is connected to each of the plurality of individual electrodes, and is driven by a driving circuit element. The ceramic substrate provided with the heating element, the flexible wiring board, and the drive circuit element are fixed on the heat sink. The flexible wiring board is bent at a substantially right angle along the side walls of the ceramic substrate and the heat sink near the solder joint with the common electrode.

By the way, in a ceramic substrate, a shearing force is repeatedly applied to a soldering joint between a conductor layer of a flexible wiring board and a common electrode due to heat generation and cooling of a heating element provided thereon, and the bonding strength is reduced. When the bonding strength decreases, the flexible wiring base There is a possibility that the soldered joint may peel off due to the restoring force of the bent portion of the plate. Accordingly, in order to reduce the restoring force, that is, the rigidity, at the bent portion of the flexible wiring board, and to reduce the above-mentioned shearing force and to accommodate excess solder generated during soldering and joining, the conductor layer In some cases, the end of the copper foil is made into a comb-like shape, and the end of the comb-like copper foil is soldered to a common electrode. Such a device is disclosed, for example, in Japanese Patent Application Laid-Open No. Hei 6-47944. However, since the end of the copper foil has a comb-like shape, that is, a slit portion, the bonding area between the common electrode and the flexible wiring board is small, and the bonding strength is low. , And there is a drawback that it is easy to peel off from the common electrode.

 Further, as an improvement of such a thermal head, a rectangular copper foil-removed portion from which the copper foil has been removed is formed along the bent portion without forming the end of the copper foil of the flexible wiring board in a comb-like shape. It is well known that a plurality of such members are provided at predetermined intervals to reduce the restoring force of the bent portion and to secure a certain bonding area with the common electrode. However, in any of the above, the amount of heat generated at both ends due to uneven distribution of heat during heating and easy release of heat at both ends of the soldered joint during soldering. Is insufficient, and the bonding strength at both ends becomes lower than at the center. In this case, the strength of the solder joint is insufficient, and the flexible wiring board is separated from the common electrode at both ends in the longitudinal direction of the solder joint. In particular, there has been a problem in that when the film is peeled off at both ends, it is greatly lifted, and the function is impaired.

The present invention solves the problems of the conventional thermal head as described above, and makes it difficult for the flexible wiring board to peel off from the common electrode even when the flexible wiring board is bent near the solder joint. The purpose is to obtain a highly reliable thermal head. The state of soldering between the common electrode and the flexible wiring board without impairing the function of the thermal head as an actual product The purpose is to obtain a thermal head that can easily estimate the thermal head. Disclosure of the invention

 The present invention is a thermal head having a holding base, a heating element, and a flexible wiring board,

 The heating element has a plurality of heating elements arranged in a straight line and a common electrode for supplying power to the heating element.

 The flexible wiring substrate has a flexible substrate and a conductor layer, the flexible substrate is formed of a flexible insulating material, and the conductor layer is a layered conductor. It has a center side and both end side conductor patterns,

 The central-side conductor pattern portion is provided with the central-side conductor portion so as to form a plurality of central-side non-conductor portions having no conductor in a predetermined direction at a predetermined position away from one end of the conductor layer by a predetermined distance. In the direction, the ratio of the center-side conductor portion to the center-side conductor portion is set to a first predetermined value,

 The conductor patterns at both ends are provided at both ends of the center conductor pattern in a predetermined direction, and the conductor patterns at both ends are formed at predetermined positions so as to form non-conductor portions without conductors in a predetermined direction in a predetermined direction. Is disposed so that the ratio of the conductor portions at both ends to the conductor pattern portions at both ends in the predetermined direction at the predetermined position is set to a second predetermined value smaller than the first predetermined value,

 A conductor layer is provided on the flexible substrate, a center-side easy-to-bend portion is formed by the flexible substrate and the center-side conductor pattern portion, and a center-side portion is formed by the flexible substrate and both end-side conductor patterns. It is formed with easy bending parts at both ends, which are less rigid than the easy bending parts.

The heating element is held by the holding base, and the flexible wiring board is soldered and joined to the common electrode of the heating element at the center and both ends and bent at the center and both end easy bending portions. It is a thing. With this configuration, the ratio occupied by both end-side conductor portions in both end-side conductor pattern portions is smaller than the ratio occupied by the center-side conductor portion in the center-side conductor pattern. Therefore, the rigidity of the flexible wiring board at the both end side easily bendable portions is lower than the rigidity at the center side easily bendable portion, and the restoring force of the bent flexible wiring board is weakened at the both end side easily bendable portions. Therefore, it is possible to prevent the flexible wiring board soldered and bonded to the common electrode from peeling off at the end in the predetermined direction, and it is possible to obtain a highly reliable thermal head. Further, in the flexible wiring board, the size of the non-conductive portions on both ends in a predetermined direction at a predetermined position is made larger than the size of the non-conductive portion on the center side.

 By this, it is only necessary to make the size of the non-conductive portion on both ends larger than the size of the non-conductive portion on the center side, so that the formation of the conductive pattern portions on both ends becomes easy. Further, the flexible substrate has a through-hole forming portion for forming a through-hole at a position corresponding to the non-conductor portion on both ends of the conductor pattern portion on both ends.

 Thereby, since the through hole is formed in the flexible substrate, the rigidity of the easily bendable portion on both ends is further reduced. Therefore, it is possible to effectively prevent the flexible wiring board from peeling off from the common electrode.

 In addition, the conductor pattern portions at both ends have a shape in which the shape of the non-conductor portions at both ends has the largest size in a predetermined direction at a predetermined position and becomes smaller from the predetermined position toward the end of the conductive layer in a direction perpendicular to the predetermined direction. It was done.

 As a result, the area of the conductor on both ends increases as the distance from the predetermined position toward the end of the conductive layer in a direction perpendicular to the predetermined direction increases, so that the solder joint area between the common electrode and the flexible wiring board increases. As the bonding strength increases, the flexible wiring board becomes more difficult to peel off.

 And a peelable device provided on the flexible wiring board, wherein the peelable device has a peelable portion and a connecting portion,

The peelable portion has a peelable conductor pattern portion and a peelable flexible substrate. The peelable conductor portion has the same shape and the same thickness as the conductor of the conductor layer so as to form a peelable nonconductive portion having the same shape as the center-side nonconductive portion. The peelable flexible substrate is formed of the same material and the same thickness as the flexible substrate, and the peelable conductive pattern portion is provided on the peelable flexible substrate.

 The connecting portion is flexible such that the peelable portion is located at the end of the flexible wiring board in the predetermined direction, and the peelable non-conductive portion is arranged in the same row in the predetermined direction as the central non-conductive portion. In this case, the peelable conductor pattern portion of the peelable portion is joined to the common electrode by soldering.

 Thus, the joint strength of the soldered portion can be known by measuring the force required to break the connecting portion and peel the peelable portion. Therefore, the joint strength of the solder joint between the common electrode and the flexible wiring board can be easily estimated without impairing the function of the thermal head as an actual product. BRIEF DESCRIPTION OF THE FIGURES

1 to 4 show a preferred embodiment of the present invention. FIG. 1 is a perspective view showing a main part of a thermal head, and FIG. 2 is a main part of a thermal head. FIG. 4 is a plan view showing a state before bending a flexible wiring board. FIG. 3 is an enlarged view of a main part showing a main part of the thermal head in FIG. 2, and FIG. 4 is a cross-sectional view taken along section line IV-IV in FIG. FIG. 5 is an enlarged view of an essential part of a thermal head showing another embodiment of the present invention, and FIG. 6 is an enlarged view of an essential part of a thermal head showing still another embodiment of the present invention. FIG. FIG. 7 is an enlarged view of a main part of a thermal head showing still another embodiment of the present invention. FIG. 8 is an enlarged view of a main part of a thermal head showing still another embodiment of the present invention. FIG. FIG. 9 is an enlarged view of a main part of a thermal head showing still another embodiment of the present invention. FIG. 10 is an enlarged view of a main part of a thermal head showing still another embodiment of the present invention. FIG. 11 is an enlarged view of a main part of a thermal head, showing still another embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

 The present invention will be described in more detail with reference to the accompanying drawings. 1 to 4 show a preferred embodiment of the present invention. FIG. 1 is a perspective view showing a main part of a thermal head by cutting out a part of the thermal head. FIG. 4 is a plan view showing a main part of the thermal head in a state before bending a flexible wiring board. FIG. 3 is an enlarged view of a main part of the thermal head in FIG. 2, and FIG. 4 is a cross-sectional view taken along section line IV—IV in FIG. The figure shows a state in which the flexible wiring board is bent along the edge of the ceramic substrate. In these figures, reference numeral 1 denotes a ceramic substrate, which has an edge 11 and has heat resistance and electrical insulation. It is formed of a ceramic material. Reference numeral 2 denotes a heating element, which includes a glaze layer (glazeelayar) 21, a resistor 22 serving as a heating element, a common electrode 23, and an independent electrode 24. The glaze layer 21 is for forming the heating element 2 on the ceramic substrate 1. The resistor 22 is formed on the glaze layer 21 on the ceramic substrate 1 and is linearly arranged in the longitudinal direction (the left-right direction in FIG. 2). One terminal of the resistor 22 is commonly connected to the common electrode 23, and the other terminal is connected to the independent electrode 24, and heat generation is selectively controlled by opening and closing the drive circuit element 3 described later. Perform the prescribed printing. Reference numeral 3 denotes a drive circuit element, which is configured by an integrated circuit in which a plurality of transistors are formed on a substrate.

Reference numeral 4 denotes a flexible wiring substrate, which has a base film 41, a conductor layer 42, a cover film 43, and a soldered layer 44 as a flexible substrate. Base fill The film 41 is a polyimide film made of a heat-resistant synthetic resin having flexibility, and has a thickness of 0.075 [mm]. The conductor layer 42 is formed of a copper foil as a rectangular conductor having a long longitudinal direction (the left-right direction in FIG. 2), which is a predetermined direction, and has a thickness of 0.050 [mm]. Affixed on base film 41 with adhesive.

 The conductor layer 42 has a terminal portion 42a, a center conductor pattern portion 42b, and both end conductor pattern portions 42c.

 As shown in FIG. 4, the terminal portion 42a is a portion of the copper foil portion exposed by removing the cover film 43 from one end to one end of a center-side copper foil removing portion 42d described later. The part from the one end shown in Fig. 3 to the bending line A, which is a distance a away from the other end (shown with diagonal lines for easy understanding) is used as a terminal.

 In the center-side conductor pattern portion 42b, a center-side copper foil removal portion 42d as a center-side non-conductor portion is formed at the position of the bending line A by removing the copper foil by etching. The size of the center-side copper foil removing portion 42d is a rectangle having a width of b and a length of c, and is provided in a predetermined number at a predetermined interval d in the longitudinal direction. The central-side copper-foil removed portion 42d is formed, and the remaining portion of the copper foil is defined as a central-side conductor portion 42h. The ratio of the center conductor portion 42h to the center conductor pattern portion 42b on the folding line A is set to a first predetermined value. In addition, the center-side copper foil removal part 42 d is symmetrical with respect to the folding line A.

 Such a center-side conductor pattern portion 4 2b is attached to the base film 41 to form a center-side easily bendable portion 42e, which is more rigid than other portions where the copper foil has not been removed. Is easy to bend.

At both ends of the conductor pattern section 4 2 c, similarly, remove copper foil on the left and right sides of the center side conductor pattern section 4 2 b at the position of the bending line A as shown in Fig. 3 to form both end side non-conductor sections. The copper foil removal portions 42 f at both ends are formed, and the remaining copper foil portions are used as the conductor portions 42 j at both ends. The copper foil removal parts on both ends 4 2 f are as shown in Fig. 3. ex Length: A rectangular shape symmetrical with respect to the bending line A of f, and the width e is larger than the width b of the copper foil removal part 42d on the middle side. The copper foil removing portions 42f at both ends are provided one at each side, but FIG. 3 shows only the left side. The copper foil on both ends is removed so that the ratio occupied by the conductor portions 42j on both ends on the bending line A in the conductor pattern portions 42c on both ends becomes a second predetermined value smaller than the first predetermined value. The size of the part is determined.

 The both end side easily bendable portion 42 g is configured by bonding both end side conductor pattern portions 42 c to the base film 41. Since the second predetermined value is smaller than the first predetermined value, that is, the ratio of the conductor portion is small, the rigidity of the both-end-side easily bendable portion 42g is lower than that of the center-side easily bendable portion 42e. The cover film 43 is a polyimide film of a heat-resistant synthetic resin having flexibility, and has a thickness of 0.075 [mm]. The cover film 43 is adhered on the conductor layer 42 with an adhesive, covers the conductor layer 42, and provides insulation protection. The soldering layer 44 is formed by melting and attaching solder to the surface of the terminal portion 42a.

 An example of the dimensions a, b, c, d, e, f described above is as follows.

 Distance to bending line A a: 2 [mm],

 Width bx length c: 0.4x2.6 [mmxmm] of center-side copper foil removal part 42d, distance between center-side copper foil removal parts 42d (width of individual conductor of center conductor part 42h) d: 0.6 [mm],

 The width e X length f: 4 X 1 [mmxmm] of the copper foil removal part at both ends 42 f.

 First predetermined value: 0.6

 Second predetermined value: 0.2

Reference numeral 5 denotes a connecting conductor, and a plurality of connecting conductors are provided in the longitudinal direction as shown in FIG. 2, and four connecting conductors are provided in this embodiment. The connection conductor 5 is soldered to the conductor layer 42. The conductor layer 42 is electrically connected to a ground member (not shown). Reference numeral 6 denotes a heat radiating plate, which has side walls 61, to which the ceramic substrate 1 is fixed in a state of good heat conduction, and radiates heat generated by the heating element 2. Reference numeral 7 denotes a peeling member, which separates an unillustrated ink sheet and paper.

 The flexible wiring board 4 has its terminal portion 42 a soldered to the common electrode 23 of the heating element 2 to form a soldered joint portion 8. The flexible wiring board 4 is bent almost at a right angle along the edge 11 of the ceramic substrate 1 and the side wall 61 of the heat sink 6 at the easily bent portions 42e and 42g at the center and both ends. ing. The bent ^! Flexible wiring board 4 is pressed by the peeling member 7. The peeling member 7 is fixed to the heat radiating plate 6 by a screw (not shown).

 The soldering of the flexible wiring board 4 and the ceramic board 1 and the fixing to the heat sink 6 are performed as follows. While keeping the flexible wiring board 4 in a flat state as shown in FIG. 3, the terminal portion 42 a is bent so that the bending line A is positioned at one end of the common electrode 23, and The common electrode 23 is brought into contact. Thereafter, the soldering layer 44 is heated while being pressed overnight, and the soldered layer 44 is melted and joined to form a soldered joint 8. Then, as shown in FIG. 4, the center and both ends of the easily bendable portions 42e and 42g are almost along the edge 11 of the ceramic substrate 1 and the side wall 61 of the heat sink 6. Bend at right angles. The bent flexible wiring board 4 is pressed by the peeling member 7, and the peeling member 7 is fixed to the heat sink 6.

According to this embodiment, the both-end-side copper-foil removing portions 4 2f wider than the center-side copper-foil removing portions 4 2d are formed at the both-end-side easily bendable portions 42g of the flexible wiring board 4. As a result, the rigidity against bending is smaller than that of the center-side easily bendable portion 42e. For this reason, when the flexible wiring board 4 is fixed to the heat radiating plate 6 in a state of being bent as shown in FIGS. 1 and 4, the restoring force generated by bending is easy to bend at both ends. In the portion 42g, it is smaller than the center side easily bendable portion 42e. Therefore, the peeling force acting on the soldered part 8 Therefore, the flexible wiring board 4 can be prevented from peeling off at both ends. In addition, the length f in the longitudinal direction of the copper foil removing portions 42 f at both ends is made smaller than the length dimension c in the longitudinal direction c of the central copper foil removing portion 42 d. In the vicinity of both ends in the hand direction, the soldering joint area with the common electrode 23 increases, and the bonding strength increases, so that the flexible wiring board 4 hardly peels off. Furthermore, since the copper foil removal portions 42 d and 42 f at the center and both ends are rectangular, when the terminal portions 42 a are soldered to the common electrode 23, they are positioned in the vertical direction in FIG. Even if there is a slight deviation, the bendability of the easily bendable portions 42 e and 42 g does not deteriorate.

 FIG. 5 is an enlarged view of a main part of a thermal head according to another embodiment of the present invention, showing a main part in an enlarged state before bending a flexible wiring board. In FIG. 5, reference numeral 140 denotes a flexible wiring board, and a base film 144 having a base film 141 is provided on both ends of the conductor pattern portion 42 c at both ends of the copper foil removing portion. Corresponding to 42 f, there is a through hole forming part 141 b that forms a through hole 141 a having the same size as the copper foil removing part 42 f at both ends. Both ends of the conductor pattern portion 42c and the through-hole forming portion 141b form an easily bendable portion 142g at both ends.

 Other configurations are the same as those shown in FIG. 3, and the corresponding components are denoted by the same reference numerals and description thereof will be omitted.

 By providing such a through-hole forming portion 141b in the base film 141, the reaction force of the base film 141 is reduced. Accordingly, the rigidity at the easily bendable portion 142g at both ends is further reduced, the bending force acting on both ends in the longitudinal direction of the soldered joint 8 is reduced, and the flexible printed circuit board 140 is peeled off. It becomes difficult to do.

The through-hole forming portion 141b may form a through-hole smaller than the copper foil removing portions 42f at both ends. Figure 6 is a further _c Figure 6 is an enlarged view showing in a state before an enlarged main portion of the head to the thermal bending the flexible wiring board showing another embodiment of the present invention In the figure, reference numeral 240 denotes a flexible wiring board, which has a conductor layer 242. The conductor layer 242 has conductor pattern portions 242c at both ends.

 The conductor pattern portion 242c at both ends has two copper foil removal portions 242f at both ends (only one shown) at each of the left and right ends on the bending line A. This part is formed by removing the copper foil. The remaining portion where the copper foil has been removed to form the copper foil removed portions 24 2 f at both ends is the conductor pattern portion 42 c at both ends. The copper foil removal part 2 42 f at both ends is enlarged asymmetrically below the figure with respect to the bending line A, and the lower end is aligned with the lower end of the center copper foil removal part 42 d in the figure. is there. The width of the copper foil removal portions at both ends 2 242 f is b, and the length is (c + f) / 2. The conductor pattern portions 242c at both ends are adhered on the base film 41, thereby forming an easily bendable portion 242g at both ends.

 Other configurations are the same as those shown in FIG. 3, and the corresponding components are denoted by the same reference numerals and description thereof will be omitted.

 In this manner, by forming the larger copper foil removing portions 2442f at both ends on the conductor pattern portions 2442c at both ends, the both ends of the flexible wiring board 240 can be easily bent. Less rigidity at 42 g. Further, the soldering area of the conductor pattern portion 242 c at both ends with the terminal portion 242 a does not change. Therefore, it is possible to more effectively prevent the flexible wiring board 240 from peeling off from the common electrode 23.

 FIG. 7 is an enlarged view of a main part of a thermal head according to another embodiment of the present invention, showing the main part of the thermal head in a state before the flexible wiring board is folded. In FIG. 7, reference numeral 340 denotes a flexible wiring board, which has a conductor layer 342. The conductor layer 342 has conductor pattern portions 342c at both ends.

At both ends of the conductor pattern section 3 4 2 c, attach Two copper foil removal portions 342 f at both ends are formed at each location (one shown on the left side in Fig. 7). The remaining copper foil portions on which the copper foil removal portions at both ends are formed are conductor portions at both ends. The copper foil removal portions 3 4 2 f at both ends are pentagons with an isosceles triangle above and a rectangle below the bend line A in the figure, and the vertex of the isosceles triangle is the copper foil on both ends in FIG. The lower side of the rectangular part is aligned with the lower side of the center-side copper foil removed part 42 d at the same position as the upper side of the removed part 42 f. Both ends of the conductor pattern portion 342c and the base film 41 form an easily bendable portion 342g of both ends.

 Other configurations are the same as those shown in FIG. 3, and the corresponding components are denoted by the same reference numerals and description thereof will be omitted.

 As described above, by forming the copper foil removing portions 3442 f at both ends having an isosceles triangular portion having a width decreasing toward the end of the conductive layer 42 at both ends of the conductor pattern portion 3442 c, The solder joint area with the terminal portion 42a at the conductor pattern portion 3442c at both ends increases. Therefore, it is possible to more effectively prevent the flexible wiring board 340 from peeling off from the common electrode 23. In addition, since the copper foil removal portions 34 2 f at both ends are pentagonal as shown in the figure, when the terminal portions 42 a are soldered to the common electrode 23, the terminal portions 42 a Be careful not to shift the position downward. If the terminal portion 42a is far below the common electrode 23 in the figure, the soldering portion 8 will straddle the triangular portion of the copper foil removal portion 3442f on both ends, and this portion This is because the stiffness is increased and the flexibility is impaired.

 FIG. 8 is an enlarged view of a main part of a thermal head according to another embodiment of the present invention, showing a main part of the thermal head in a state before the flexible wiring board is bent, by enlarging the main part. In FIG. 8, reference numeral 440 denotes a flexible wiring board, which has a conductor layer 442. The conductor layer 442 has conductor pattern portions 442c at both ends.

The conductor pattern section 4 4 2c at both ends has two At each location, a total of two (the left one is shown in Fig. 8) copper foil removal parts 442 f at both ends are formed. The remaining copper foil portions on which the copper foil removal portions 442 f at both ends are formed are the conductor portions 442 j at both ends. The copper foil removal portions 4 4 2 f at both ends are such that the portion on the folding line A is the widest along the folding direction near the folding line A, and becomes narrower as the distance from the folding line A in the folding direction increases. This is a quadrilateral (diamond) as shown in the figure, formed by removing the copper foil and symmetric with respect to the folding line A and having the same length on all sides. Both ends of the conductor pattern portion 442c and the base film 41 form an easily bendable portion 442g at both ends.

 Other configurations are the same as those shown in FIG. 3, and the corresponding components are denoted by the same reference numerals and description thereof will be omitted.

 In this way, by forming the diamond-shaped copper foil-removed portions 442: f at both ends of the conductive pattern portions 442c, the widths of which are reduced toward the ends of the conductive layer 42, f The soldering joint area with the terminal portion 42a in the pattern portion 4442c can be increased. Therefore, it is possible to effectively prevent the flexible wiring board 4400 from peeling off from the common electrode 23.

 Also, since the copper foil removal portions 442c at both ends are rhombic as shown, when the terminal portions 42a are soldered to the common electrode 23, the terminal portions 42a are shown in FIG. Be careful not to shift the position vertically. If the terminal portion 42 a is shifted too much in the vertical direction in the figure with respect to the common electrode 23, the soldering portion 8 will straddle the triangular portion of the copper foil removing portion 4 4 2 f on both ends. This is because the stiffness of the steel is increased and the flexibility is impaired.

FIG. 9 is an enlarged view of a main part of a thermal head according to another embodiment of the present invention, showing the main part of the thermal head in a state before the flexible wiring board is folded. In FIG. 9, reference numeral 540 denotes a flexible wiring board, which has a conductor layer 542. The conductor layer 542 has a center-side conductor pattern portion 542b and both-end-side conductor pattern portions 442c. A predetermined number of center-side copper foil removing portions 542 d are formed in the center-side conductor pattern portion 542b in the longitudinal direction along the bending line A. The remaining copper foil portion on which the center-side copper-foil removed portion 542 d is formed is the center-side conductor portion 542h. The center-side conductor pattern portion 542 b is a rhombus having a width b and a length c symmetrical with respect to the bending line A. The center-side easy-to-bend portion 5 4 2 e is formed by the center-side conductor pattern portion 5 4 2 b and the base film 41, and the both-end-side easily bendable portion 4 4 is formed by both end-side conductor pattern portions 4 4 2 c and the base film 4 1. 2 g are formed.

 Other configurations are the same as those shown in FIG. 3, and the corresponding components are denoted by the same reference numerals and description thereof will be omitted.

 By forming the diamond-shaped central-side copper foil removal portion 542 d in the central-side conductor pattern portion 542 b in this manner, the center-side easy-to-bend portion 542 e of the flexible wiring board 540 is formed. It is possible to increase the soldering joint area with the terminal portion 42a while keeping the rigidity of the terminal portion low. Therefore, the center-side easily bendable portion 542e of the flexible wiring substrate 540 can be more securely soldered to the common electrode 23. When soldering to the common electrode 23, care should be taken in the alignment with the terminal portion 42a so that the flexibility of the bent portion is not impaired.

 FIG. 10 is an enlarged view of a main part of a thermal head according to another embodiment of the present invention, showing the main part of the thermal head in a state before the flexible wiring board is folded. . In FIG. 10, reference numeral 640 denotes a flexible wiring board, which has a conductor layer 640. The conductor layer 642 has conductor pattern portions 642c at both ends.

In the conductor pattern portions 642c at both ends, copper foil removal portions 6442e at both ends are formed on the fold line A. The copper foil removal portions 6 4 2 e at both ends are copper LINE removal of the same size bxc as the center side conductor removal portions 4 2 d in Fig. 3 where four are arranged at regular intervals as shown in the figure. The part is formed by removing the copper foil into a rectangle having a width e X and a length f so as to penetrate these four copper foil removal parts on the folding line A, and has a shape as shown in the figure. The remaining part is the conductor part 6 4 2 j on both ends _c In this embodiment, the first predetermined value is 0.6, and the second predetermined value is about 0.15.

 The conductor pattern portions 642c at both ends and the base film 41 form the easy bending portions 642g at both ends.

 FIG. 11 is an enlarged view of a main part of a thermal head according to another embodiment of the present invention, showing a main part of the thermal head in a state before the flexible wiring board is bent by bending. In FIG. 11, reference numeral 9 denotes a peeling test device, which has a test piece portion 91, a through-hole forming portion 92, and a minute connecting portion 93, each of which has a copper foil 9a on a base film 9b. It is formed by being adhered to. The copper foil 9a has the same thickness of 0.050 [mm] as the conductor layer 42 of the flexible wiring board 4. The base film 9b as the peelable flexible substrate is made of the same polyimide resin as the base film 41 and has a thickness of 0.075 [mm].

 The test piece portion 91 as a peelable portion has a test piece conductor pattern portion 9 1b as a peelable portion conductor pattern portion and has a peelable non-conductive portion having the same shape as the central copper foil removed portion 4 2 d. The test piece copper foil removing portion 91 a is formed. The copper foil is removed by etching to form a test piece copper foil removal portion 91a, and the remaining portion is a test piece conductor portion 91c as a peelable conductor portion. As shown in the figure, the peeling test apparatus 9 has a test piece copper foil removing section 9 la arranged at the end of the flexible wiring board 4 so as to be aligned with the center side copper foil removing section 42 d. The part 91 is connected to the flexible wiring board 4 by a minute connecting part 93. In addition, the minute connecting portion 93 can be cut with a cutting tool such as a nipper and easily separated from the flexible wiring board 4. Further, the through-hole forming portion 92 forms a through-hole 92a.

 Other configurations are the same as those shown in FIG. 3, and the corresponding components are denoted by the same reference numerals and description thereof will be omitted.

Such a peel test apparatus 9 is manufactured as follows. When manufacturing the flexible wiring board 4, the base film and the copper foil are increased by the peeling test apparatus 9. The copper foil is removed, and the copper foil removal part 9 la is formed at a predetermined position. The other portion is punched and removed with a breath except for the minute connecting portion 93 to obtain a peeling test device 9. At this time, the through holes 92a are simultaneously formed by punching. When the soldering layer 44 is formed on the flexible wiring board 4, the test piece 91 is also plated with solder. Then, when the flexible wiring board 4 is soldered to the common electrode 23, the soldered layer of the test piece 91 is melted and soldered to the common electrode 23 at the same time.

 In the peeling test apparatus 9 configured as described above, when it is desired to measure the soldering joint strength of the test piece section 91, the minute connecting section 93 is cut with a nipper, and for example, using a spring scale. The hook strength can be easily measured by hooking the hook in the through hole 92a and pulling it. From this strength, the actual bonding strength of the soldered joint 8 is estimated.

 According to this embodiment, it is possible to easily measure the bonding strength in a peeling test apparatus using a thermal head actually used as a product, so that the actual soldered joint 8 can be measured without impairing the function as a product. Since pass / fail can be estimated, reliability of the bridge can be improved.

In each of the above embodiments, the base film and the cover film are described as polyimide films. However, films formed of other insulating materials, such as polyester, may be used. Further, the conductor layer is not limited to the copper foil, and the same effect can be obtained even if the conductor layer is formed of a conductive material such as gold. Further, the thickness of the base film, the cover film, or the conductor layer is not limited to the illustrated one. Further, the shape of the copper foil removal portions on the center side and both sides is not limited to the shape described above, and may be another shape such as an elliptical shape. In addition, instead of forming the copper foil removal part on both ends larger than the copper foil removal part on both end conductor patterns, for example, the same as the central copper foil removal part 4 2 d (dimension bxc) in Fig. 3 Remove the copper foil of the size Even in the case of the both-end-side conductor pattern portions formed at intervals smaller than the interval, the rigidity against bending can be similarly reduced. Industrial applicability

 As described above, the thermal head according to the present invention is useful when used in a thermal type printing apparatus such as a thermal type or a thermal transfer type. Such a thermal printer can be widely used as an output device of a computer / facsimile.

Claims

The scope of the claims 1. A thermal head having a holding base, a heating element, and a flexible wiring board, wherein the heating element includes a plurality of heating elements arranged in a straight line and power is supplied to the heating element. And a common electrode to be supplied,  The flexible wiring substrate has a flexible substrate and a conductor layer, and the flexible substrate is formed of a flexible insulating material. It is formed of a layered conductor, and has a center side and both end side conductor pattern portions,  The center-side conductor pattern portion is provided with a center-side conductor portion so as to form a plurality of center-side non-conductor portions having no conductor in a predetermined direction at a predetermined position separated from one end of the conductor layer by a predetermined distance. The ratio of the central conductor portion to the central conductor portion in the predetermined direction of the position is set to a first predetermined value,  The conductor pattern portions on both ends are provided on both ends in the predetermined direction of the conductor pattern portion on the center side, and form conductor-free portions on both ends without conductors in the predetermined direction at the predetermined positions. Both ends of the conductor portion are disposed, and a ratio of the both ends of the conductor pattern to the both ends of the conductor pattern portion in the predetermined direction at the predetermined position is a second predetermined value smaller than the first predetermined value. The flexible substrate and the conductor layer are provided on the flexible substrate, and the flexible substrate and the central conductor pattern portion form a central-side easy-to-bend portion. The conductor path portion forms an easily bendable portion on both ends having lower rigidity than the above-mentioned center-side easily bendable portion, The heating element is held by the holding base, and the flexible wiring board is bent at the predetermined position while the center side and both end side conductive pattern portions are soldered to the common electrode of the heating element. Is Hey manor head.  2. The flexible wiring board according to claim 1, wherein the size of the non-conductive portion at both ends in a predetermined direction at a predetermined position is larger than the size of the non-conductive portion at the center. Thermal head as described in the item. 3. The flexible substrate according to claim 1, wherein the flexible substrate has a through-hole forming portion for forming a through-hole at a position corresponding to the non-conductive portion on both ends of the conductive pattern portion on both ends. The head of the country.  4. The conductor pattern portions at both ends are shaped such that the shape of the non-conductor portions at both ends is the largest in the predetermined direction at the predetermined position and becomes smaller from the predetermined position toward the end of the conductive layer in a direction perpendicular to the predetermined direction. The thermal head according to claim 1, wherein the thermal head has been manufactured.  5. A peelable device provided on a flexible wiring board, wherein the peelable device has a peelable portion and a connecting portion,  The peelable portion has a peelable conductive pattern portion and a peelable flexible substrate, and the peelable conductive pattern portion has a peelable nonconductive portion having the same shape as the center-side nonconductive portion. A peelable conductor having the same thickness and the same material as the conductor of the conductor layer is provided so as to be formed, and the peelable flexible substrate is formed of the same material and the same thickness as the flexible substrate. A peelable conductor pattern portion is provided on the peelable flexible substrate,  The connecting portion is arranged such that the peelable portion is located at an end portion of the flexible wiring board in a predetermined direction, and the peelable non-conductive portion is arranged in the same row as the central non-conductive portion in a predetermined direction. To connect and support the flexible wiring board integrally and breakably,  2. The thermal head according to claim 1, wherein said peelable conductor pattern portion of said peelable portion is soldered to a common electrode.