Bonded body, imaging unit, endoscope, hard substrate, and bonding method

Abstract

This bonded body comprises: a hard substrate that has a first terminal, a step portion, and a wire provided from the first terminal to the step portion; and a flexible substrate that has a second terminal on the distal side thereof in the extension direction of the wire and that is disposed opposite the hard substrate. The step portion protrudes further to the flexible substrate side in comparison to the first terminal in an opposing direction in which the hard substrate and the flexible substrate are opposite one another. The hard substrate and the flexible substrate are bonded by means of solder connection between the first terminal and the second terminal.

Description

Joint, imaging unit, endoscope, hard substrate, and joining method

[0001] This application claims priority to PCT / JP2024 / 014599, filed April 10, 2024, the contents of which are incorporated herein by reference.

[0002] Conventionally, side-viewing endoscopes have been known in which the imaging surface of an imager is arranged along the longitudinal direction of the endoscope. In such side-viewing endoscopes, a flexible substrate is soldered to a rigid substrate on which the imager is mounted, and a cable is connected to the rear end of the flexible substrate. The rigid substrate and the flexible substrate have a plurality of corresponding connection terminals, and the corresponding connection terminals are electrically connected by being soldered together.

[0003] JP 2005-101026 A JP 2017-183686 A

[0004] However, when soldering a hard substrate and a flexible substrate together, if the amount of solder squeezing is too large, adjacent connection terminals may be connected to each other by the solder, which may cause a short circuit in the wiring.

[0005] In light of the above circumstances, an object of the present disclosure is to provide a joined body, an imaging unit, an endoscope, a hard substrate, and a joining method that prevent the amount of solder being crushed too much when soldering.

[0006] In order to solve the above problems, the present disclosure proposes the following means: A joined body of the present disclosure includes a rigid substrate having a first terminal, a step portion, and a wiring provided from the first terminal to the step portion, and a flexible substrate disposed opposite the rigid substrate and having a second terminal on the tip side in the extension direction of the wiring, the step portion protruding toward the flexible substrate beyond the first terminal in the opposing direction in which the rigid substrate and the flexible substrate face each other, and the rigid substrate and the flexible substrate are joined by soldering the first terminal and the second terminal.

[0007] The imaging unit of the present disclosure includes the above-described bonded body and an imager connected to the wiring.

[0008] The endoscope of the present disclosure includes the imaging unit described above at the tip of the insertion section.

[0009] The rigid substrate of the present disclosure is a rigid substrate that is joined opposite to a flexible substrate, and includes a first terminal, a step portion that protrudes more toward the flexible substrate than the first terminal in the opposing direction in which the rigid substrate and the flexible substrate are opposed, and wiring that is provided from the first terminal to the step portion, wherein the step portion is located closer to the tip side than the first terminal in the extension direction of the wiring, and the first terminal is solder-connected to a second terminal that is provided on the tip side of the flexible substrate.

[0010] The bonding method disclosed herein is a bonding method for bonding a rigid substrate having a first terminal, a step portion, and wiring extending from the first terminal to the step portion, to a flexible substrate having a second terminal and arranged opposite the rigid substrate, in which solder is sandwiched and arranged between the first terminal and the second terminal in the opposing direction in which the rigid substrate and the flexible substrate face each other, and the bottom surface of a heater chip is brought into contact with a pressing area formed in a portion of the step portion closer to the flexible substrate in the opposing direction than the first terminal, and with the wiring extended therefrom, and with the surface of the flexible substrate opposite the second terminal.

[0011] According to the bonded body, imaging unit, endoscope, hard substrate, and bonding method disclosed herein, it is possible to provide a bonded body, imaging unit, endoscope, hard substrate, and bonding method that prevent the amount of solder being crushed too much when soldering.

[0012] FIG. 11 is a diagram showing an endoscopic system including an endoscope according to a first embodiment. FIG. 12 is a cross-sectional view showing an imaging unit provided in the endoscope. FIG. 13 is an enlarged cross-sectional view showing a joined body provided in the imaging unit. FIG. 14 is a plan view showing a joined body according to a second embodiment. FIG. 15 is a cross-sectional view taken along line V-V in FIG. 4. FIG. 16 is a plan view showing a joined body according to a third embodiment. FIG. 17 is a cross-sectional view taken along line VII-VII in FIG. 6. FIG. 18 is a plan view showing a joined body according to a fourth embodiment. FIG. 19 is a cross-sectional view taken along line IX-IX in FIG. 8. FIG. 19 is a plan view showing a joined body according to a fifth embodiment. FIG. 20 is a plan view showing a joined body according to a sixth embodiment. FIG. 21 is a cross-sectional view taken along line XII-XII in FIG. 22. FIG. 22 is a cross-sectional view taken along line XIII-XIII in FIG. 23. FIG. 23 is a plan view showing a joined body according to a seventh embodiment. FIG. 24 is a plan view showing a joined body according to an eighth embodiment.

[0013] First Embodiment A first embodiment of the present disclosure will be described with reference to the drawings.

[0014] 1 is a diagram showing an endoscope system 1. The endoscope system 1 includes an endoscope 2 that is inserted into a body and generates image signals by capturing images of the inside of the body.

[0015] The endoscope 2 is a flexible endoscope, and includes an insertion section 200 that is inserted into the body from the tip, and an endoscope operation section 210 attached to the base end of the insertion section 200.

[0016] The insertion section 200 has a tip section 200a, a bending section 200b, and a flexible section 200c. The tip section 200a, the bending section 200b, and the flexible section 200c are arranged in this order from the tip of the insertion section 200.

[0017] A channel 230 for inserting a treatment tool 240 is provided inside the insertion portion 200. An opening 200d of the channel 230 is provided on the side surface of the tip portion 200a.

[0018] The bending section 200b bends in accordance with the operator's operation of the endoscope operation section 210. The flexible section 200c is a flexible tubular section.

[0019] The endoscope operation section 210 is connected to the proximal end of the flexible section 200c and includes an input section 211, a switch section 213, a proximal end opening 212 of the channel 230, and a universal cord (not shown).

[0020] The input unit 211 receives an operation input for performing a bending operation on the bending portion 200b.

[0021] The switch unit 213 receives operation inputs from peripheral devices such as an information processing device, a light source device, an air supply device, a water supply device, and a gas supply device (not shown). For example, the endoscope operation unit 210 has a plurality of switch units 213 corresponding to each operation input.

[0022] A treatment tool 240 can be inserted into the proximal end opening 212 of the channel 230. The treatment tool 240 inserted through the channel 230 can be protruded and retracted through the opening 200d at the tip of the endoscope 2.

[0023] The operator operates a treatment tool operating portion 241 provided at the proximal end of the treatment tool 240 to cause the treatment tool 240 to protrude and retract from the opening 200d.

[0024] The universal cord includes an imaging cable (not shown) connected to the imaging unit 100 (described later) and outputs to the outside an image captured by the imaging unit 100. The universal cord is connected to a display device such as a liquid crystal display via an image processing device including a processor or the like.

[0025] Next, the configuration of the imaging unit 100 provided at the tip portion 200a of the endoscope 2 will be described.

[0026] FIG. 2 is a cross-sectional view showing the imaging unit 100. As shown in FIG.

[0027] Here, the side of the tip portion 200a of the endoscope 2 where the opening 200d is provided is referred to as the "upper side Z1," and the side opposite the upper side Z1 is referred to as the "lower side Z2." Also, the direction connecting the upper side Z1 and the lower side Z2 is referred to as the "up-down direction Z."

[0028] Furthermore, the longitudinal direction of the endoscope 2 is referred to as the "axial direction X," and in the axial direction X, the side inserted into the patient's body is referred to as the "tip side (distal side) X1," and the side toward the endoscope operating unit 210 is referred to as the "base side (proximal side) X2."

[0029] The imaging unit 100 includes a joint 7 , an imager 10 , a light-guiding component 6 , and a cable 3 .

[0030] The joined body 7 includes a hard substrate 4 and a flexible substrate 5. The joined body 7 is formed by joining the hard substrate 4 and the flexible substrate 5. Details of the hard substrate 4 and the flexible substrate 5 will be described later.

[0031] The imager 10 has a lens unit 11 having an objective lens, and an image sensor 12 that converts an optical image formed by the objective lens into an image signal.

[0032] The imager 10 is mounted on the top surface 4a (top surface Z1) of the hard substrate 4 at the end on the tip side X1.

[0033] The lens unit 11 includes, for example, a plurality of objective lenses and a lens frame that holds the objective lenses. The lens frame of the lens unit 11 is fixed inside the distal end portion 200 a of the insertion portion 200 .

[0034] The lens unit 11 is disposed so that an endoscope axis O1 extending in the longitudinal direction (axial direction X) of the endoscope 2 intersects with an optical axis O2 of the lens unit 11.

[0035] 2, the angle θ at which the endoscope axis O1 intersects with the optical axis O2 of the lens unit 11 is 90°. An endoscope 2 equipped with an imaging unit 100 with an angle θ of 90° is called a side-viewing endoscope. The endoscope 2 may also be a forward-viewing endoscope with an angle θ of 0° or greater and less than 90°.

[0036] The image sensor 12 is, for example, a CCD or CMOS, and captures an image of an object to be observed. The image sensor 12 is disposed so that the image sensor surface 12a is perpendicular to the optical axis O2 of the lens unit 11. In other words, the image sensor surface 12a of the image sensor 12 is disposed along the endoscope axis O1.

[0037] A sensor electrode (not shown) is formed on the surface of the lower side Z2 of the image sensor 12. The image sensor 12 is preferably a CSP (Chip Size Package) in which wiring, electrode formation, resin sealing, and dicing are performed on an image sensor chip in a wafer state, and the final size of the image sensor 12 is the same as the size of the image sensor chip.

[0038] A cover glass (not shown) that protects the image sensor 12 is adhered with an optical adhesive to the upper side Z1 of the image sensor 12. The lens unit 11 is disposed above the upper side Z1 of the image sensor 12 via the cover glass.

[0039] The light-guiding part 6 is a light-guiding member that guides light to be irradiated onto an imaging target of the imager 10. The light-guiding part 6 extends in the axial direction X on the lower side Z2 of the joint body 7, and is arranged so that the tip side X1 is bent to the upper side Z1. The light-guiding part 6 covers the joint body 7 from the lower side Z2 and the tip side X1.

[0040] The hard substrate 4 has an imager mounting area 40 on an upper surface 4a on the tip side X1, where the imager 10 is disposed. In this embodiment, the hard substrate 4 is a double-sided substrate.

[0041] An electrical component mounting area 42 is formed at the end of the tip side X1 of the lower surface 4b (the surface on the lower side Z2) of the hard substrate 4, where an electrical component 14 such as electronic components is mounted.

[0042] The electrical component 14 is disposed on the opposite side of the imaging element 12 with the hard substrate 4 interposed therebetween.

[0043] A step portion 8 that protrudes downward Z2 is formed on the lower surface 4b of the hard substrate 4 on the base end side X2 beyond the electrical component mounting area 42. The step portion 8 will be described in detail later.

[0044] A first terminal 41 for connecting the flexible substrate 5 is formed on the lower surface 4b of the hard substrate 4. In this embodiment, the first terminal 41 is provided on the base end side X2 from the stepped portion 8.

[0045] The rigid substrate 4 has a higher bending strength than the flexible substrate 5 and is made of a material that does not deform. For the rigid substrate 4, for example, a glass cloth composite, ceramic, thermosetting resin, thermoplastic resin, or the like can be used.

[0046] The flexible substrate 5 is disposed opposite the hard substrate 4 in the vertical direction Z. The flexible substrate 5 has a second terminal 50 solder-connected to the first terminal 41 of the hard substrate 4, and a cable connection portion 51 connected to the cable 3.

[0047] The second terminal 50 is provided on the upper surface 5a of the flexible substrate 5 at an end on the tip side X1.

[0048] The cable connection portion 51 is provided on the lower surface 5b of the flexible substrate 5 near the end of the base end side X2.

[0049] The flexible substrate 5 extends parallel to the endoscope axis O1. The surface of the flexible substrate 5 is parallel to the surface of the hard substrate 4.

[0050] The flexible substrate 5 is provided with wiring (not shown) that electrically connects the second terminal 50 and the cable connection portion 51 .

[0051] The flexible substrate 5 is a substrate having flexibility and a lower bending strength than the rigid substrate 4. For the flexible substrate 5, for example, a glass cloth composite material, ceramic, thermosetting resin, thermoplastic resin, or the like can be used.

[0052] The cable 3 is a cable with a covered cable core 31 that performs signal input / output between the imager 10 and the outside, or power supply from the outside to the imager 10, etc.

[0053] The cable 3 is routed from the composite cable 30 , and the cable core wire 31 is connected to the cable connection portion 51 of the flexible substrate 5 .

[0054] The composite cable 30 is formed, for example, by covering a plurality of bundled cables 3 with a shield covering 32. The cable core wires 31 of the plurality of cables 3 with the shield covering 32 unwrapped are connected to the cable connection portion 51.

[0055] Next, the joining portion between the hard substrate 4 and the flexible substrate 5 will be described in detail.

[0056] 3 is an enlarged cross-sectional view showing the bonded portion between the hard substrate 4 and the flexible substrate 5 in the bonded body 7 in which the hard substrate 4 and the flexible substrate 5 are bonded together. In FIG. 3, the upper side of the paper surface is the lower side Z2 in the vertical direction Z, and the lower side of the paper surface is the upper side Z1 in the vertical direction Z.

[0057] In the following description, the vertical direction Z in which the hard substrate 4 and the flexible substrate 5 face each other will also be referred to as the "facing direction Z."

[0058] 3, the step portion 8 protrudes downward Z2 from the first terminal 41. That is, the step portion 8 protrudes toward the flexible substrate 5 from the first terminal 41 in the opposing direction Z in which the hard substrate 4 and the flexible substrate 5 oppose each other.

[0059] The hard substrate 4 is, for example, a three-dimensionally molded substrate, and is integrally formed with the step portion 8. The step portion 8 may be formed by stacking a substrate on the hard substrate 4.

[0060] In this embodiment, the step portion 8 is disposed closer to the tip side X1 than the first terminal 41. A pressing region 8a is formed on the surface of the lower side Z2 of the step portion 8.

[0061] The pressing area 8 a is a portion of the step portion 8 that is disposed closer to the flexible substrate 5 than the first terminal 41 .

[0062] In this embodiment, the pressing area 8a and the first terminal 41 are connected via an inclined portion 8b that is inclined downward Z2 from the first terminal 41, as shown in FIG.

[0063] A wiring 4 c connected to the first terminal 41 is provided on the lower surface 4 b of the hard substrate 4 .

[0064] The wiring 4c is provided on the lower surface 4b of the hard substrate 4 so as to extend in the axial direction X. That is, the extension direction of the wiring 4c coincides with the axial direction X.

[0065] The wiring 4c is routed on the lower surface 4b of the hard substrate 4 and electrically connects, for example, the imager mounting area 40, the electrical component mounting area 42, and the first terminal 41.

[0066] In this embodiment, the imager mounting area 40 provided on the upper surface 4a of the hard substrate 4 and the electrical component mounting area 42 provided on the lower surface 4b of the hard substrate 4 are connected, for example, via a through hole that penetrates the hard substrate 4 in the vertical direction Z.

[0067] 3, the wiring 4c is provided from the first terminal 41 to the step portion 8. In the present embodiment, the wiring 4c extends from the first terminal 41 to the tip side X1 and extends to the inclined portion 8b and the pressing region 8a.

[0068] In the opposing direction Z, solder S is disposed between the first terminal 41 and the second terminal 50. The first terminal 41 and the second terminal 50 are solder-connected by the solder S, thereby being electrically connected to each other.

[0069] Next, a method for joining the hard substrate 4 and the flexible substrate 5 will be described.

[0070] In this embodiment, when the hard substrate 4 and the flexible substrate 5 are joined together, the solder S is sandwiched and disposed between the first terminal 41 and the second terminal 50 in the opposing direction Z.

[0071] As shown in FIG. 3, the hard substrate 4 and the flexible substrate 5 are joined by pressing the bottom surface of the heater chip HC against the hard substrate 4 and the flexible substrate 5 and melting the solder S.

[0072] Here, the joint 7 formed by joining the hard substrate 4 and the flexible substrate 5 is arranged such that the pressing area 8a and the surface (lower surface 5b) opposite the second terminal 50 of the flexible substrate 5 are at approximately the same height in the opposing direction Z.

[0073] The solder S before being melted by the heat of the heater chip HC has a larger dimension in the facing direction Z than the solder S shown in FIG.

[0074] Before the hard substrate 4 and the flexible substrate 5 are joined, the dimension obtained by adding the dimension of the flexible substrate 5 in the opposing direction Z and the dimension of the solder S in the opposing direction Z is greater than the dimension in the opposing direction Z from the first terminal 41 to the pressing area 8a.

[0075] By pressing the heater chip HC against the lower surface 5 b of the flexible substrate 5 , the solder S is crushed by the flexible substrate 5 .

[0076] When the solder S is crushed, the flexible substrate 5 moves toward the hard substrate 4 in the facing direction Z.

[0077] When the flexible substrate 5 moves toward the hard substrate 4 and the pressure area 8 a and the lower surface 5 b of the flexible substrate 5 become flush with each other, the heater chip HC comes into contact with the pressure area 8 a of the step portion 8 .

[0078] Therefore, the step portion 8 restricts the movement of the heater chip HC in the facing direction Z, and it is possible to prevent the amount of compression of the solder S from becoming too large beyond a predetermined amount of compression.

[0079] The rigid substrate 4 has, for example, a plurality of wirings 4 c and a plurality of first terminals 41 connected to the plurality of wirings 4 c. The flexible substrate 5 has a plurality of second terminals 50 corresponding to the plurality of first terminals 41.

[0080] If the amount of compression of the solder S is greater than a predetermined amount, for example, adjacent wirings 4c may be connected to each other by the solder S, which may cause a short circuit in the wirings 4c.

[0081] By suppressing the amount of solder S that is crushed by the step portion 8, it is possible to prevent short circuits of the wiring 4c.

[0082] When the hard substrate 4 and the flexible substrate 5 are joined by the heater chip HC, the heat of the heater chip HC is transferred to the solder S via the flexible substrate 5 .

[0083] In addition, in this embodiment, when the heater chip HC comes into contact with the pressing area 8a, the heat of the heater chip HC is transferred to the first terminal 41 via the wiring 4c extending to the pressing area 8a, and the heat is transferred from the first terminal 41 to the solder S.

[0084] That is, in this embodiment, heat from the heater chip HC is transferred to the solder S from both sides in the facing direction Z via the flexible substrate 5 and the wiring 4c of the rigid substrate 4. Therefore, heat can be transferred to the solder S efficiently, and the solder S can be melted efficiently.

[0085] For example, a conventional method for joining a rigid substrate and a flexible substrate involves sandwiching a separate restricting member between the rigid substrate and the flexible substrate to limit the amount of solder squeezing. In this case, heat from the heater chip pressed against the flexible substrate is transferred to the solder only through the flexible substrate.

[0086] By contacting the heater chip HC with the pressing area 8a of the step portion 8 to which the wiring 4c is extended and suppressing the amount of crushing of the solder S, heat can be transferred from the first terminal 41 side to the solder S, and solder joining can be performed more stably compared to when the amount of crushing of the solder is suppressed by a conventional restricting member.

[0087] The bonded body 7 of this embodiment includes a hard substrate 4 having a first terminal 41, a step portion 8, and a wiring 4c extending from the first terminal 41 to the step portion 8, and a flexible substrate 5 having a second terminal 50 on the tip side X1 in the extension direction (axial direction X) of the wiring 4c and arranged opposite the hard substrate 4.

[0088] The step portion 8 protrudes further toward the flexible substrate 5 than the first terminal 41 in the opposing direction (vertical direction) Z in which the hard substrate 4 and the flexible substrate 5 face each other.

[0089] The hard substrate 4 and the flexible substrate 5 are joined by soldering the first terminal 41 and the second terminal 50 with solder S.

[0090] The step portion 8 of the bonded body 7 can suppress the amount of crushing of the solder S, thereby preventing short-circuiting of the wiring 4c.

[0091] Second Embodiment A second embodiment of the present disclosure will be described.

[0092] In the following description, the same components as those already described will be assigned the same reference numerals and redundant description will be omitted.

[0093] Fig. 4 is a plan view showing a bonded body 7A according to the second embodiment, and Fig. 5 is a cross-sectional view taken along line VV in Fig. 4.

[0094] In the following description, the direction perpendicular to the axial direction X and the opposing direction Z is defined as the "width direction Y," one side in the width direction Y is defined as the "right side Y1," and the other side in the width direction Y is defined as the "left side Y2."

[0095] The joint body 7A is provided in the imaging unit 100 of the endoscope 2, similar to the joint body 7 of the first embodiment. The joint body 7A has a hard substrate 4A and a flexible substrate 5.

[0096] In this embodiment, the hard substrate 4A has two wirings 4c as shown in FIGS. 4 and 5, but the number of wirings 4c that the hard substrate 4A has is not limited to this.

[0097] A sub-step portion 9 is provided in the vicinity of the first terminal 41 of the hard substrate 4A.

[0098] The sub-step portions 9 are provided on both sides (the right side Y1 and the left side Y2) of the flexible substrate 5 in the width direction Y. In addition, in the width direction Y, the wiring 4c and the first terminal 41 are disposed between the two sub-step portions 9.

[0099] The sub-step portion 9 protrudes further to the lower side Z2 than the first terminal 41 in the facing direction Z. A sub-pressing region 9a is formed on the surface of the sub-step portion 9 on the lower side Z2.

[0100] The secondary pressing region 9 a is a portion of the secondary step portion 9 that is disposed closer to the flexible substrate 5 than the first terminal 41 .

[0101] The hard substrate 4A is provided with a sub-wiring 4d branched from the wiring 4c. In this embodiment, the sub-wiring 4d extends to the right Y1 and left Y2 from a first terminal 41 connected to the wiring 4c.

[0102] The sub-wiring 4d may branch off from the wiring 4c in the pressing region 8a or the inclined portion 8b.

[0103] A sub-wiring 4d branching from the wiring 4c extends to a sub-pressure region 9a of the sub-step portion 9.

[0104] In this embodiment, when the hard substrate 4A and the flexible substrate 5 are joined together, the solder S is sandwiched and disposed between the first terminal 41 and the second terminal 50 in the opposing direction Z.

[0105] In this embodiment, the hard substrate 4A and the flexible substrate 5 are joined by pressing the bottom surface of the heater chip HC against the hard substrate 4A and the flexible substrate 5 and melting the solder S, as shown in FIG.

[0106] Here, the joined body 7A, in which the hard substrate 4A and the flexible substrate 5 are joined, is arranged such that the secondary pressing area 9a and the surface (lower surface 5b) opposite the second terminal 50 of the flexible substrate 5 are at approximately the same height in the opposing direction Z.

[0107] The solder S before being melted by the heater chip HC has a larger dimension in the facing direction Z than the solder S shown in FIG.

[0108] Before the hard substrate 4A and the flexible substrate 5 are joined, the dimension obtained by adding the dimension of the flexible substrate 5 in the opposing direction Z and the dimension of the solder S in the opposing direction Z is larger than the dimension in the opposing direction Z from the first terminal 41 to the secondary pressing area 9a.

[0109] By pressing the heater chip HC against the lower surface 5 b of the flexible substrate 5 , the solder S is crushed by the flexible substrate 5 .

[0110] When the solder S is crushed, the flexible substrate 5 moves in the facing direction Z toward the hard substrate 4A.

[0111] When the flexible substrate 5 moves toward the hard substrate 4A and the secondary pressure area 9a and the lower surface 5b of the flexible substrate 5 become flush with each other, the heater chip HC comes into contact with the secondary pressure area 9a of the secondary step portion 9.

[0112] Therefore, the sub-step portion 9 restricts the movement of the heater chip HC in the facing direction Z, and it is possible to prevent the amount of compression of the solder S from becoming too large beyond a predetermined amount of compression.

[0113] By suppressing the amount of solder S that is crushed by the sub-step portion 9, it is possible to prevent short circuits of the wiring 4c.

[0114] In this embodiment, when the heater chip HC comes into contact with the secondary pressure region 9a, the heat of the heater chip HC is transferred to the wiring 4c or the first terminal 41 via the secondary wiring 4d extending to the secondary pressure region 9a, and the heat is transferred from the first terminal 41 to the solder S, so that the heat can be transferred to the solder S efficiently and the solder S can be melted efficiently.

[0115] The sub-wiring 4d may be made of a metal different from that of the wiring 4c as long as it can transfer the heat of the heater chip HC from the sub-pressure region 9a to the first terminal 41.

[0116] In the bonded body 7A of this embodiment, the hard substrate 4A has a sub-step portion 9 in addition to the step portion 8, so that the amount of crushing of the solder S can be more reliably prevented from becoming greater than the predetermined amount of crushing, thereby preventing short circuits of the wiring 4c.

[0117] Third Embodiment A third embodiment of the present disclosure will be described.

[0118] Fig. 6 is a plan view showing a bonded body 7B according to the third embodiment, and Fig. 7 is a cross-sectional view taken along line VII-VII in Fig. 6.

[0119] The joint body 7B is provided in the imaging unit 100 of the endoscope 2, similar to the joint body 7 of the first embodiment. The joint body 7B has a hard substrate 4B and a flexible substrate 5.

[0120] In this embodiment, the hard substrate 4B has three wirings 4c as shown in FIG. 6, but the number of wirings 4c that the hard substrate 4B has is not limited to this.

[0121] As shown in FIG. 7, in the bonded body 7B, the second terminal 50 of the flexible substrate 5 is disposed opposite the step portion 8 of the hard substrate 4B in the facing direction Z.

[0122] In this embodiment, when joining the flexible substrate 5 to the hard substrate 4B, solder S is placed between the pressing area 8a, which is the part of the step portion 8 on the flexible substrate 5 side, and the second terminal 50 in the opposing direction Z, and the heater chip HC is pressed against the underside 5b of the flexible substrate 5.

[0123] At least a part of the solder S is crushed by the flexible substrate 5 against which the heater chip HC is pressed, and is pushed out to both sides of the step portion 8 in the axial direction X (extension direction of the wiring 4c).

[0124] In addition, in the hard substrate 4B, the first terminals 41 are provided on both sides of the step portion 8 in the axial direction X.

[0125] The solder S is pushed out to both sides of the step portion 8 in the axial direction X, so that the first terminal 41 and the second terminal 50 are joined and electrically connected via the solder S.

[0126] When the heater chip HC is pressed against the flexible substrate 5 to crush the solder S, the flexible substrate 5 abuts against the pressing area 8a of the step portion 8 and does not move toward the first terminal 41 (upper side Z1) beyond the pressing area 8a.

[0127] Since the solder S pushed out to both sides of the step portion 8 in the axial direction X is not crushed by the flexible substrate 5, the amount of solder S crushed can be prevented from becoming too large, and short-circuiting of the wiring 4c can be prevented.

[0128] Furthermore, since the solder S crushed by the flexible substrate 5 escapes to both sides of the step portion 8 in the axial direction X, the solder S remaining between the second terminal 50 and the pressing area 8a can prevent adjacent wirings 4c from being electrically connected to each other, thereby preventing short circuits of the wirings 4c.

[0129] In this embodiment, the first terminals 41 are provided on both sides of the stepped portion 8 in the axial direction X, but may be provided on either the tip end side X1 or the base end side X2 of the stepped portion 8. Furthermore, when the heater chip HC is pressed against the flexible substrate 5 to crush the solder S, the solder S may be pushed out toward the tip end side X1 or the base end side X2 of the stepped portion 8 on which the first terminals 41 are provided.

[0130] Even if the first terminal 41 is provided on either the tip side X1 or the base side X2 of the step portion 8, and the solder S is pushed out toward the side where the first terminal 41 is provided on the tip side X1 or the base side X2 of the step portion 8, the first terminal 41 and the second terminal 50 can be joined by the solder S, thereby electrically connecting the hard substrate 4B and the flexible substrate 5.

[0131] When the first terminal 41 is provided on both sides of the step portion 8 in the axial direction X, there is no need to control the direction in which the solder S is pushed out when joining the hard substrate 4B and the flexible substrate 5, and the first terminal 41 and the second terminal 50 can be easily joined by the solder S.

[0132] Fourth Embodiment A fourth embodiment of the present disclosure will be described.

[0133] Fig. 8 is a plan view showing a bonded body 7C according to the fourth embodiment, and Fig. 9 is a cross-sectional view taken along line IX-IX in Fig. 8.

[0134] The joint body 7C is provided in the imaging unit 100 of the endoscope 2, similar to the joint body 7 of the first embodiment. The joint body 7C has a hard substrate 4C and a flexible substrate 5.

[0135] In this embodiment, the hard substrate 4C has three wirings 4c as shown in FIG. 8, but the number of wirings 4c that the hard substrate 4C has is not limited to this.

[0136] As shown in FIG. 9, in the bonded body 7C, the second terminal 50 of the flexible substrate 5 is disposed opposite the step portion 8 of the rigid substrate 4C in the facing direction Z.

[0137] 8, the step portion 8 of the hard substrate 4C is provided so as to overlap the wiring 4c in a plan view from the facing direction Z, and is provided at the center of the wiring 4c in the width direction Y. The step portion 8 does not need to be provided strictly at the center of the wiring 4c in the width direction Y. Furthermore, the step portion 8 of the hard substrate 4C extends in the axial direction X along the wiring 4c.

[0138] As shown in FIG. 9, the first terminals 41 of the hard substrate 4C are provided on both sides of the step portion 8 in the width direction Y.

[0139] In this embodiment, when joining the flexible substrate 5 to the rigid substrate 4C, solder S is placed between the pressing area 8a, which is the part of the step portion 8 on the flexible substrate 5 side, and the second terminal 50 in the opposing direction Z, and the heater chip HC is pressed against the underside 5b of the flexible substrate 5.

[0140] At least a part of the solder S is crushed by the flexible substrate 5 against which the heater chip HC is pressed, and is pushed out to both sides of the step portion 8 in the width direction Y.

[0141] The solder S is pushed out to both sides of the step portion 8 in the width direction Y, so that the first terminal 41 and the second terminal 50 are joined and electrically connected via the solder S.

[0142] When the heater chip HC is pressed against the flexible substrate 5 to crush the solder S, the flexible substrate 5 abuts against the pressing area 8a of the step portion 8 and does not move toward the first terminal 41 beyond the pressing area 8a.

[0143] Since the solder S pushed out to both sides of the step portion 8 in the width direction Y is not crushed by the flexible substrate 5, the amount of solder S crushed can be prevented from becoming too large, and short-circuiting of the wiring 4c can be prevented.

[0144] In this embodiment, the first terminals 41 are provided on both sides of the step portion 8 in the width direction Y, but may be provided on either the right side Y1 or the left side Y2 of the step portion 8. Furthermore, when the heater chip HC is pressed against the flexible substrate 5 to crush the solder S, the solder S may be pushed out toward the side of the step portion 8 on the right side Y1 or the left side Y2 where the first terminals 41 are provided.

[0145] Even if the first terminal 41 is provided on either the right side Y1 or the left side Y2 of the step portion 8 and the solder S is pushed out toward the side of the step portion 8 on the right side Y1 or the left side Y2 where the first terminal 41 is provided, the first terminal 41 and the second terminal 50 can be joined by the solder S, thereby electrically connecting the hard substrate 4C and the flexible substrate 5.

[0146] When the first terminal 41 is provided on both sides of the step portion 8 in the width direction Y, there is no need to control the direction in which the solder S is extruded when joining the hard substrate 4C and the flexible substrate 5, and the first terminal 41 and the second terminal 50 can be easily joined by the solder S.

[0147] Fifth Embodiment A fifth embodiment of the present disclosure will be described.

[0148] FIG. 10 is a plan view showing a bonded body 7D according to the fifth embodiment.

[0149] The joint body 7D is provided in the imaging unit 100 of the endoscope 2, similar to the joint body 7 of the first embodiment. The joint body 7D has a hard substrate 4D and a flexible substrate 5.

[0150] In this embodiment, the hard substrate 4D has three wirings 4c as shown in FIG. 10, but the number of wirings 4c that the hard substrate 4D has is not limited to this.

[0151] 10 , the step portion 8 of the hard substrate 4D is provided so as to overlap the wiring 4c in a plan view from the facing direction Z, and is provided at the center of the wiring 4c in the width direction Y. The step portion 8 does not need to be provided strictly at the center of the wiring 4c in the width direction Y.

[0152] In addition, in the axial direction X, the dimensions of the step portion 8 of the hard substrate 4D are smaller than the dimensions of the wiring 4c, and the step portion 8 of the hard substrate 4D is surrounded by the wiring 4c in a plan view from the opposing direction Z.

[0153] The first terminal 41 of the hard substrate 4D is provided so as to surround the step portion 8 in plan view from the facing direction Z.

[0154] In this embodiment, when joining the flexible substrate 5 to the hard substrate 4D, solder S is placed between the pressing area 8a, which is the part of the step portion 8 on the flexible substrate 5 side, and the second terminal 50 in the opposing direction Z, and the heater chip HC is pressed against the underside 5b of the flexible substrate 5.

[0155] In the bonded body 7D, a cross-sectional view along the opposing direction Z and the axial direction X is similar to the cross-sectional view shown in FIG. 7, and a cross-sectional view along the opposing direction Z and the width direction Y is similar to the cross-sectional view shown in FIG.

[0156] At least a part of the solder S is crushed by the flexible substrate 5 against which the heater chip HC is pressed, and is pushed out to both sides of the step portion 8 in the axial direction X and both sides in the width direction Y.

[0157] By pushing out the solder S to both sides of the step portion 8 in the axial direction X and both sides in the width direction Y, the first terminal 41 and the second terminal 50 are joined and electrically connected via the solder S.

[0158] When the heater chip HC is pressed against the flexible substrate 5 to crush the solder S, the flexible substrate 5 abuts against the pressing area 8a of the step portion 8 and does not move toward the first terminal 41 beyond the pressing area 8a.

[0159] Since the solder S extruded to both sides of the step portion 8 in the axial direction X and both sides in the width direction Y is not crushed by the flexible substrate 5, the amount of solder S crushed can be prevented from becoming too large, and short-circuiting of the wiring 4c can be prevented.

[0160] In this embodiment, the first terminal 41 is provided to surround the step portion 8 in a plan view from the facing direction Z, but may be provided on any one of the tip side X1, base side X2, right side Y1, or left side Y2 of the step portion 8. Furthermore, when the heater chip HC is pressed against the flexible substrate 5 to crush the solder S, the solder S may be pushed out toward the tip side X1, base side X2, right side Y1, or left side Y2 of the step portion 8 on which the first terminal 41 is provided.

[0161] Even if the first terminal 41 is provided on either the tip side X1, base side X2, right side Y1 or left side Y2 of the step portion 8, and the solder S is pushed out toward the tip side X1, base side X2, right side Y1 or left side Y2 of the step portion 8 on which the first terminal 41 is provided, the first terminal 41 and the second terminal 50 can be joined by the solder S, thereby electrically connecting the hard substrate 4D and the flexible substrate 5.

[0162] When the first terminal 41 is arranged surrounding the step portion 8, there is no need to control the direction in which the solder S is extruded when joining the hard substrate 4D and the flexible substrate 5, and the first terminal 41 and the second terminal 50 can be easily joined by the solder S.

[0163] Sixth Embodiment A sixth embodiment of the present disclosure will be described.

[0164] Fig. 11 is a plan view showing a bonded body 7E according to the sixth embodiment, Fig. 12 is a cross-sectional view taken along line XII-XII in Fig. 11, and Fig. 13 is a cross-sectional view taken along line XIII-XIII in Fig. 11.

[0165] The joint body 7E is provided in the imaging unit 100 of the endoscope 2, similar to the joint body 7 of the first embodiment. The joint body 7E has a hard substrate 4E and a flexible substrate 5.

[0166] In this embodiment, the hard substrate 4E has three wirings 4c as shown in FIG. 11, but the number of wirings 4c that the hard substrate 4E has is not limited to this.

[0167] As shown in FIG. 11 , the step portion 8 of the hard substrate 4E is provided so as to overlap the wiring 4c in a plan view from the facing direction Z, and is provided so as to surround the first terminal 41.

[0168] In this embodiment, when joining the flexible substrate 5 to the hard substrate 4E, solder S is placed between the pressing area 8a, which is the part of the step portion 8 on the flexible substrate 5 side, and the second terminal 50 in the opposing direction Z, and the heater chip HC is pressed against the underside 5b of the flexible substrate 5.

[0169] 12 and 13, the dimensions of the second terminal 50 of the flexible substrate 5 in the axial direction X and the width direction Y are equal to or larger than the dimensions of the step portion 8 provided surrounding the first terminal 41 of the rigid substrate 4E.

[0170] In this embodiment, when the flexible substrate 5 is joined to the rigid substrate 4E, the second terminals 50 and the solder S are disposed so as to cover the step portion 8 .

[0171] At least a part of the solder S is crushed by the flexible substrate 5 against which the heater chip HC is pressed, and enters the area surrounded by the step portion 8. The second terminal 50 and the first terminal 41 surrounded by the step portion 8 are joined and electrically connected by the solder S that has entered the area surrounded by the step portion 8.

[0172] When the heater chip HC is pressed against the flexible substrate 5 to crush the solder S, the flexible substrate 5 abuts against the pressing area 8a of the step portion 8 and does not move toward the first terminal 41 beyond the pressing area 8a.

[0173] The solder S that has entered the area surrounded by the step portion 8 is not crushed by the flexible substrate 5, so that the amount of solder S that is crushed can be prevented from becoming too large.

[0174] Furthermore, when the heater chip HC is pressed against the flexible substrate 5 to crush the solder S, there is a possibility that the solder S will be pushed out of the step portion 8. The outside of the step portion 8 refers to the area on the tip side X1, base side X2, right side Y1, or left side Y2 of the step portion 8, and indicates an area where the first terminals 41 are not provided.

[0175] When the heater chip HC is pressed against the flexible substrate 5 to crush the solder S, the flexible substrate 5 abuts against the pressing area 8a, so that the solder S pushed out to the outside of the step portion 8 is not crushed by the flexible substrate 5.

[0176] Therefore, even if the solder S is pushed out to the outside of the step portion 8, the amount of the solder S that is squeezed out can be prevented from becoming too large, and a short circuit of the wiring 4c can be prevented.

[0177] Seventh Embodiment A seventh embodiment of the present disclosure will be described.

[0178] FIG. 14 is a plan view showing a bonded body 7F according to the seventh embodiment.

[0179] The joint body 7F is provided in the imaging unit 100 of the endoscope 2, similar to the joint body 7 of the first embodiment. The joint body 7F has a hard substrate 4F and a flexible substrate 5.

[0180] In this embodiment, the rigid substrate 4F has three wirings 4c as shown in FIG. 14, but the number of wirings 4c that the rigid substrate 4F has is not limited to this.

[0181] 14 , the step portions 8 of the hard substrate 4F are provided on both sides of the first terminal 41 in the axial direction X. The wiring 4c of the hard substrate 4F is provided across the two step portions 8 provided on the tip end side X1 and the base end side X2 of the first terminal 41.

[0182] In this embodiment, when joining the flexible substrate 5 to the rigid substrate 4F, solder S is placed between the pressing area 8a, which is the part of the step portion 8 on the flexible substrate 5 side, and the second terminal 50 in the opposing direction Z, and the heater chip HC is pressed against the underside 5b of the flexible substrate 5.

[0183] In the present embodiment, the second terminal 50 is disposed across two step portions 8 as shown in Fig. 14. In the bonded body 7F, a cross-sectional view taken along the opposing direction Z and the axial direction X is similar to the cross-sectional view shown in Fig. 12.

[0184] In this embodiment, when the flexible substrate 5 is joined to the rigid substrate 4F, the second terminals 50 and the solder S are arranged to face the two step portions 8 in the facing direction Z.

[0185] At least a part of the solder S is crushed by the flexible substrate 5 against which the heater chip HC is pressed, and enters between the two step portions 8 in the axial direction X. The second terminal 50 and the first terminal 41 provided between the two step portions 8 are joined and electrically connected by the solder S that has entered between the two step portions 8.

[0186] The solder S crushed by the flexible substrate 5 may be pushed out to the tip side X1 or the base side X2 of the two step portions 8.

[0187] When the heater chip HC is pressed against the flexible substrate 5 to crush the solder S, the flexible substrate 5 abuts against the pressing area 8a of the step portion 8 and does not move toward the first terminal 41 beyond the pressing area 8a.

[0188] The solder S that has entered between the two step portions 8 and the solder S that has been pushed out to the tip end side X1 or base end side X2 of the two step portions 8 is not crushed by the flexible substrate 5, so that the amount of crushing of the solder S can be prevented from becoming too large, and short-circuiting of the wiring 4c can be prevented.

[0189] Furthermore, since the solder S crushed by the flexible substrate 5 escapes between the two step portions 8 or to the tip side X1 or base side X2 of the two step portions 8, the solder S remaining between the second terminal 50 and the pressing area 8a can prevent adjacent wirings 4c from being electrically connected to each other, thereby preventing short circuits of the wirings 4c.

[0190] Eighth Embodiment An eighth embodiment of the present disclosure will be described.

[0191] FIG. 15 is a plan view showing a bonded body 7G according to the eighth embodiment.

[0192] The joint body 7G is provided in the imaging unit 100 of the endoscope 2, similar to the joint body 7 of the first embodiment. The joint body 7G has a hard substrate 4G and a flexible substrate 5.

[0193] In this embodiment, the hard substrate 4G has three wirings 4c as shown in FIG. 15, but the number of wirings 4c that the hard substrate 4G has is not limited to this.

[0194] 15 , the step portions 8 of the hard substrate 4G are provided on both sides of the first terminal 41 in the axial direction X. The wiring 4c of the hard substrate 4G is provided across the two step portions 8 provided on the tip end side X1 and the base end side X2 of the first terminal 41.

[0195] In this embodiment, when joining the flexible substrate 5 to the rigid substrate 4G, solder S is placed between the pressing area 8a, which is the part of the step portion 8 on the flexible substrate 5 side, and the second terminal 50 in the opposing direction Z, and the heater chip HC is pressed against the underside 5b of the flexible substrate 5.

[0196] In the present embodiment, the second terminal 50 is provided across two step portions 8 as shown in Fig. 15. In the bonded body 7G, a cross-sectional view taken along the opposing direction Z and the axial direction X is similar to the cross-sectional view shown in Fig. 12.

[0197] Furthermore, the step portion 8 of the hard substrate 4G is provided so as to overlap the wiring 4c in a plan view from the facing direction Z, and is provided at the center of the wiring 4c in the width direction Y. The step portion 8 does not need to be provided strictly at the center of the wiring 4c in the width direction Y.

[0198] In this embodiment, when the flexible substrate 5 is joined to the rigid substrate 4G, the second terminals 50 and the solder S are arranged to face the two step portions 8 in the facing direction Z.

[0199] At least a part of the solder S is crushed by the flexible substrate 5 against which the heater chip HC is pressed, and enters between the two step portions 8 in the axial direction X. The second terminal 50 and the first terminal 41 provided between the two step portions 8 are joined and electrically connected by the solder S that has entered between the two step portions 8.

[0200] The solder S crushed by the flexible substrate 5 may be pushed out to the right Y1 or left Y2 of the two step portions 8.

[0201] When the heater chip HC is pressed against the flexible substrate 5 to crush the solder S, the flexible substrate 5 abuts against the pressing area 8a of the step portion 8 and does not move toward the first terminal 41 beyond the pressing area 8a.

[0202] The solder S that has entered between the two step parts 8 and the solder S that has been pushed out to the right Y1 or left Y2 of the two step parts 8 is not crushed by the flexible substrate 5, so that the amount of crushing of the solder S can be prevented from becoming too large, and short-circuiting of the wiring 4c can be prevented.

[0203] Although the embodiments of the present disclosure have been described above in detail with reference to the drawings, the specific configurations are not limited to these embodiments and include design modifications within the scope of the present disclosure. Furthermore, the components shown in the above-described embodiments and the modified examples shown below can be configured in any suitable combination.

[0204] (Variant 1) In each of the above embodiments, the flexible substrate 5 is bonded to the surface of the hard substrate 4, 4A, 4B, 4C, 4D, 4E, 4F, or 4G opposite to the surface on which the imager 10 is provided, but the form of the flexible substrate is not limited to this.

[0205] The flexible substrate may be bonded to the same surface of the rigid substrate as the imager 10. In this case, the first terminal, the step portion, the wiring, the sub-step portion, and the sub-wiring of the rigid substrate are provided on the surface of the rigid substrate to which the flexible substrate is bonded.

[0206] (Variation 2) In each of the above embodiments, the endoscope 2 is a side-viewing endoscope, but the form of the endoscope is not limited to this. The endoscope may be an oblique-viewing endoscope or a direct-viewing endoscope in which the optical axis of the imager extends in the axial direction of the endoscope.

[0207] (Modification 3) In the second embodiment, the hard substrate 4A has the step portion 8 and the sub-step portion 9, but the form of the hard substrate is not limited to this. The hard substrate may not have the step portion 8 and may have only the sub-step portion 9.

[0208] Even if the hard substrate has only the sub-step portion 9, the amount of crushing of the solder S can be suppressed by the sub-step portion 9, thereby preventing short circuits. In addition, the sub-wiring 4d extending to the sub-step portion 9 can efficiently transfer heat to the solder S.

[0209] (Modification 4) In the second embodiment, the hard substrate 4A has two sub-step portions 9, but the form of the hard substrate is not limited to this. The number of sub-step portions 9 that the hard substrate has may be one.

[0210] Even if the rigid substrate has only one sub-step portion 9 provided on the right side Y1 or the left side Y2, the amount of crushing of the solder S can be suppressed by the sub-step portion 9, thereby preventing short circuits. In addition, the sub-wiring 4d extending to the sub-step portion 9 can efficiently conduct heat to the solder S.

[0211] REFERENCE SIGNS LIST 1 Endoscope system 2 Endoscope 200 Insertion section 100 Imaging unit 10 Imager 7, 7A, 7B, 7C, 7D, 7E, 7F, 7G Bonded body 4, 4A, 4B, 4C, 4D, 4E, 4F, 4G Hard substrate 41 First terminal 4c Wiring 4d Sub-wiring 8 Step portion 8a Pressing area 9 Sub-step portion 9a Sub-pressing area 5 Flexible substrate 50 Second terminal S Solder HC Heater chip Z Opposing direction (vertical direction) X Axial direction (extension direction of wiring) X1 Tip side X2 Base side

Claims

1. A joined body comprising: a rigid substrate having a first terminal, a step portion, and a wiring extending from the first terminal to the step portion; and a flexible substrate having a second terminal at the tip end in the extension direction of the wiring and arranged opposite the rigid substrate, wherein the step portion protrudes further toward the flexible substrate than the first terminal in the opposing direction in which the rigid substrate and the flexible substrate are opposed, and the rigid substrate and the flexible substrate are joined by soldering the first terminal and the second terminal.

2. The joined body according to claim 1, wherein the step portion has a pressing area formed closer to the flexible substrate than the first terminal and to which the wiring extends, and the pressing area and the surface of the flexible substrate opposite the second terminal in the opposing direction are positioned at approximately the same height.

3. The joined body according to claim 1, wherein the rigid substrate has sub-step portions that protrude further toward the flexible substrate than the first terminals and are provided on both sides of the flexible substrate in a direction different from the extension direction.

4. The joined body according to claim 3, wherein the rigid substrate has a sub-wiring branched from the wiring, and the sub-step portion has a sub-pressure region located closer to the flexible substrate than the first terminal and to which the sub-wiring extends.

5. The joined body described in claim 1, wherein the step portion has a pressing area formed on the flexible substrate side of the first terminal and to which the wiring extends, and the rigid substrate and the flexible substrate are joined by bringing the bottom surface of the heater chip into contact with the pressing area and the surface of the flexible substrate opposite the second terminal.

6. The joined body according to claim 1, wherein the step portion is provided closer to the tip side than the first terminal.

7. The joined body according to claim 1, wherein the step portion is provided closer to the base end in the extension direction than the first terminal.

8. The joined body according to claim 1, wherein the first terminals are provided on both sides of the step portion in the extension direction.

9. The joined body according to claim 1, wherein the first terminals are provided on both sides of the step portion in a direction different from the extension direction.

10. The joined body according to claim 1, wherein the step portion is provided on both sides of the first terminal in the extension direction.

11. The joined body according to claim 1, wherein the step portion is provided to surround the first terminal in a plan view from the opposing direction.

12. The joined body according to claim 1, wherein the first terminal is provided so as to surround the step portion in a plan view from the opposing direction.

13. An imaging unit comprising: the assembly according to claim 1; and an imager connected to the wiring.

14. An endoscope comprising the imaging unit according to claim 13 at the tip of an insertion section.

15. A rigid substrate joined opposite to a flexible substrate, comprising: a first terminal; a step portion that protrudes further toward the flexible substrate than the first terminal in the opposing direction in which the rigid substrate and the flexible substrate are opposed; and wiring provided from the first terminal to the step portion, wherein the step portion is located closer to the tip than the first terminal in the extension direction of the wiring, and the first terminal is solder-connected to a second terminal provided on the tip side of the flexible substrate.

16. A method for joining a rigid substrate having a first terminal, a step portion, and wiring extending from the first terminal to the step portion, to a flexible substrate having a second terminal and disposed opposite the rigid substrate, the method comprising: arranging solder between the first terminal and the second terminal in the opposing direction in which the rigid substrate and the flexible substrate face each other; and contacting the bottom surface of a heater chip with a pressing area formed on the flexible substrate side of the step portion in the opposing direction relative to the first terminal, and with the wiring extended therefrom, and with the surface of the flexible substrate opposite the second terminal.

Images