ELECTRIC WIRE CONNECTION STRUCTURE AND ELECTRIC WIRE CONNECTION STRUCTURE MANUFACTURING METHOD

An electric wire connection structure includes a plurality of electric wires each having a covered portion, at which a core wire is covered with a covering, and a core wire exposed portion, at which the core wire is exposed from the covering, the exposed core wire portions being arranged in parallel to each other; an electronic component including a plurality of electrodes respectively connected to the core wire exposed portions of the plurality of electric wires; and a core wire fixing member to fix the plurality of core wire exposed portions to each other.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is based on Japanese patent application No. 2023-115887 filed on Jul. 14, 2023, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

This disclosure relates to an electric wire connection structure and a method for manufacturing an electric wire connection structure.

BACKGROUND OF THE INVENTION

Patent Literature 1 discloses an electric wire connection structure that includes plural electrodes provided on a pressure sensor for catheter treatment and plural electric wires respectively connected to the plural electrodes. The plural electric wires are arranged so that core wire exposed portions, at which core wires are exposed, are aligned in parallel and connected to the plural electrodes.

CITATION LIST

Patent Literature 1: US Patent Application Publication No. 2015/0137274

SUMMARY OF THE INVENTION

In the electric wire connection structure described in Patent Literature 1, it is difficult to maintain the distances between the plural core wire exposed portions.

The invention was made in view of such circumstances and it is an object to provide an electric wire connection structure in which the distances between plural core wire exposed portions are easily maintained, and a method for manufacturing an electric wire connection structure.

To achieve the above object, one aspect of the invention provides an electric wire connection structure, comprising:a plurality of electric wires each comprising a covered portion, at which a core wire is covered with a covering, and a core wire exposed portion, at which the core wire is exposed from the covering, the exposed core wire portions being arranged in parallel to each other;an electronic component comprising a plurality of electrodes respectively connected to the core wire exposed portions of the plurality of electric wires; anda core wire fixing member to fix the plurality of core wire exposed portions to each other.

To achieve the above object, another aspect of the invention provides a method for manufacturing an electric wire connection structure, comprising:arranging in parallel core wire exposed portions of a plurality of electric wires at which core wires are exposed from coverings, and fixing the core wire exposed portions with a core wire fixing member, thereby fixing electric wires; andafter the fixing electric wires, connecting the core wire exposed portions of the plurality of electric wires respectively to a plurality of electrodes of an electronic component.

Advantageous Effects of the Invention

According to the invention, it is possible to provide an electric wire connection structure in which the distances between plural core wire exposed portions are easily maintained and a method for manufacturing an electric wire connection structure.

DETAILED DESCRIPTION OF THE INVENTION

First Embodiment

The first embodiment will be described in reference toFIGS.1to8. The embodiment below is described as a preferred illustrative example for implementing the invention. Although some part of the embodiment specifically illustrates various technically preferable matters, the technical scope of the invention is not limited to such specific aspects.

FIG.1is a perspective view showing an electric wire connection structure1in the first embodiment.FIG.2is a plan view showing the electric wire connection structure1.FIG.3is a cross-sectional view passing through core wires31of plural electric wires3and showing the electric wire connection structure1.FIG.4is a cross-sectional view taken along line IV-IV inFIG.2as viewed in the arrow direction.

The electric wire connection structure1in the first embodiment constitutes a device used for a medical device that is inserted into the body. Medical devices inserted into the body must be small in size and diameter to e.g. allow for insertion into the body and reduce the burden on the human body. As an example, a guidewire equipped with a pressure sensor is expected to be a medical device that includes the electric wire connection structure1in the first embodiment. The guidewire is to guide the movement of the catheter inside the body.

The use of the electric wire connection structure1is not limited thereto, and the electric wire connection structure1may be used for, e.g., a medical device inserted into the body, other than the guidewire. The wire connection structure1can also be used in applications other than medical devices as long as the structure is used to connect plural electric wires3to plural electrodes21of an electronic component2.

The electric wire connection structure1in the first embodiment includes the electronic component2, the plural electric wires3, a core wire fixing member4, and a sealing material5. The electronic component2includes the plural electrodes21. The plural electric wires3each include a covered portion301at which a core wire31is covered with a covering32, and a core wire exposed portion302at which the core wire31is exposed from the covering32. The core wire exposed portions302of the plural electric wires3are arranged in parallel. Hereinafter, the longitudinal direction of each core wire exposed portion302will be referred to as the “axial direction X”, the direction in which the plural core wire exposed portions302are aligned will be referred to as the width direction Y, and the direction orthogonal to both the axial direction X and the width direction Y will be referred to as the height direction Z. The core wire fixing member4fixes the plural core wire exposed portions302to each other. The sealing material5seals the plural electrodes21, the tip portions of the plural electric wires3, and the core wire fixing member4. For convenience,FIG.1shows only the respective outlines of the core wire fixing member4and the sealing material5, which are indicated by broken lines.

The electronic component2is formed in a rectangular parallelepiped shape that is long in the axial direction X and has a thickness in the height direction Z. The electronic component2includes a sensor unit20and the plural electrodes21. In the first embodiment, the sensor unit20is a pressure sensor that detects pressure inside a blood vessel. Although detailed illustrations are omitted, the pressure sensor includes a diaphragm that flexes under the pressure of blood and a Wheatstone bridge having a strain gauge whose electrical resistance decreases with the deformation of the diaphragm (e.g., the pressure sensor described in JP 2023-39717A). The electronic component2may be an electronic component other than the sensor.

The plural electrodes21consist of a total of three electrodes: one input electrode to apply voltage to the Wheatstone bridge of the sensor unit20, and two output electrodes respectively connected to two points of the Wheatstone bridge between which the potential difference changes according to the pressure acting on the diaphragm. The number of electrodes21provided on the electronic component2may be two or may be not less than four as long as it is more than one. The same applies to the number of electric wires3connected to the electrodes21.

The three electrodes21are formed of a wiring pattern formed a surface of the electronic component2on one side in the height direction Z. The three electrodes21each have a rectangular plate shape which is long in the axial direction X and short in the width direction Y and are arranged in parallel in the width direction Y. The width of the three electrodes21is, e.g., not more than 0.1 mm. The three electrodes21are arranged at a pitch of, e.g., not more than 0.1 mm. The core wire exposed portions302of the three electric wires3are respectively connected to the three electrodes21.

The electric wire3includes the core wire31and the covering32. The core wire31is made of a highly conductive material such as a copper alloy plated with silver or gold, etc., and is formed of a solid wire with a circular cross-section. Plating the core wire31with silver or gold, etc., makes it easier to solder the core wire31to the electrode21, as described later. The diameter of the core wire31is, e.g., not more than 0.05 mm. In this regard, the core wire31may be formed of a stranded wire. However, when using the solid wire, it is easier to form a straight shape, and the three core wire exposed portions302are kept parallel to each other easily. In case the core wire31is a stranded wire, the diameter of the core wire31can be the diameter of a circumscribed circle of the plural strands constituting the core wire31.

The covering32is made of an electrically insulating resin. In the first embodiment, the covering32is made of, e.g., a highly heat-resistant fluorine-based resin such as PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) or PTFE (polytetrafluoroethylene).

As described above, the electric wire3includes the covered portion301, at which the core wire31is covered with the covering32, and the core wire exposed portion302, at which the core wire31is exposed from the covering32. Tip end surfaces321of the respective coverings32of the three electric wires3are aligned at the same position, and the core wire exposed portions302protrude from the tip end surfaces321of the coverings32toward the tip side. As shown inFIGS.3and4, a length L in the axial direction X from the tip end surfaces321of the coverings32of the three electric wires3to the electronic component2is, e.g., not more than 0.5 mm. The core wire exposed portions302of the three electric wires3are arranged in a row, parallel to each other. The core wire exposed portions302in positions parallel to the electrode21are connected to the electrode21.

The plural core wire exposed portions302are respectively connected to the plural electrodes21using a conductive bonding material6that melts and hardens with temperature change. In the first embodiment, the conductive bonding material6is made of a solder that melts on heating and hardens on cooling, particularly an Au-Sn-based solder with a relatively high melting temperature. However, the material of the conductive bonding material6is not limited thereto and may be a solder made of another material. The three core wire exposed portions302are fixed to each other by the core wire fixing member4at the opposite side to the portions connected to electrodes21.

The core wire fixing member4fixes the three core wire exposed portions302such that the pitch between the three core wire exposed portions302is the same as the pitch between the three electrodes21. The core wire fixing member4covers the entire circumference of each of the three core wire exposed portions302and integrates them together.

The core wire fixing member4is formed by hardening a molten resin filling around the three core wire exposed portions302and has electrical insulation properties. The core wire fixing member4is made of a heat-resistant material that can withstand the heating temperature when joining the core wire exposed portion302to the electrode21with the conductive bonding material6. For example, the core wire fixing member4is made of an ultraviolet (UV)-curable epoxy adhesive, etc. The core wire fixing member4can be made of, e.g., a material not adhesive to the covering32, but may be made of a material adhesive to the covering32in the same manner as the sealing material5(described later).

The core wire fixing member4covers base portions of the three core wire exposed portions302(i.e., the end portions on the side where the tip end surfaces321of the coverings32are located). As shown inFIGS.3and4, at least a portion of the core wire fixing member4is arranged on the side where the tip end surfaces321of the coverings32are located, relative to a center position C between the electronic component2and the tip end surfaces321of the coverings32in the axial direction X. In the first embodiment, the entire core wire fixing member4is arranged on the side where the tip end surfaces321of the coverings32are located, relative to the center position C. In particular, in the first embodiment, the core wire fixing member4has a contact surface41which is in contact with the tip end surfaces321of the three coverings32. When the positions of the tip end surfaces321of the three coverings32are not aligned, the center position C is a center position between the electronic component2and the tip end surface321located closest to the electronic component2among the tip end surfaces321of the three coverings32.

FIG.5is a cross-sectional view taken along line V-V inFIG.2as viewed in the arrow direction. The core wire fixing member4is formed in a bulk shape with a thickness T (i.e., the dimension in the height direction Z) of not less than a diameter D of the core wire31. In other words, the core wire fixing member4is not a thin film formed on the surface of each core wire31, but is formed in a thick shape that fills gaps between the three core wire exposed portions302and has the thickness T of not less than the diameter D of the core wire31. By forming the core wire fixing member4in a bulk shape, the strength of the core wire fixing member4is ensured and the distances between the three core wire exposed portions302are easily maintained. When, e.g., the core wire fixing member4has a distorted shape and has different thicknesses in different portions, the thickness T means the maximum thickness of the core wire fixing member4.

The sealing material5covers the three electrodes21, the three core wire exposed portions302, tip portions of the three covered portions301and the core wire fixing member4to suppress ingress of moisture such as blood into the conductive portions of the wire connection structure1. The sealing material5is made of a material that is adhesive to the fluorine-based resin constituting the covering32. As an example, the sealing material5can be made of a cyanoacrylate adhesive, etc. that has been subjected to treatment to improve adhesion, such as primer treatment.

Method for Manufacturing Electric Wire Connection Structure

Next, a method for manufacturing the electric wire connection structure1in the first embodiment will be described.

In the method for manufacturing the electric wire connection structure1in the first embodiment, an electric wire preparation step, an electric wire fixing step, a connecting step and a sealing step are performed in this order.

FIG.6is a plan view showing the three electric wires3prepared in the electric wire preparation step. In the electric wire preparation step, the three electric wires3each having the core wire exposed portion302are prepared. In the first embodiment, the core wire exposed portions302are formed by partially removing the coverings32from the three electric wires3. The position of the tip end surface321of the covering32and the length of the core wire exposed portion302are the same for the three electric wires3.

After the electric wire preparation step, the electric wire fixing step is performed.FIG.7is a plan view showing the three electric wires3and the core wire fixing member4after the electric wire fixing step. In the electric wire fixing step, first, the three core wire exposed portions302are arranged in parallel at the same pitch as the three electrodes21. To arrange the three core wire exposed portions302in parallel, e.g., a tool having three grooves formed at the same pitch as the three electrodes21is used and the three core wire exposed portions302are respectively placed in the three grooves. The three core wire exposed portions302can thereby be arranged in parallel.

The three core wire exposed portions302arranged in parallel are fixed to each other by the core wire fixing member4. When a UV-curable resin is used as the core wire fixing member4, a molten resin to be the core wire fixing member4is applied to cover the three core wire exposed portions302and is cured by irradiation with ultraviolet light, and the core wire fixing member4is thereby obtained. In the first embodiment, the core wire fixing member4is formed so as to be in contact with the tip end surfaces321of the three coverings32as described above. In case that the core wire fixing member4is formed so as to be in contact with the tip end surfaces321of the three coverings32, the molten resin to be the core wire fixing member4easily spreads along the tip end surfaces321of the three coverings32and is easily formed in a bulk shape. The core wire fixing member4may be formed by a method other than coating application, and, e.g., a mold, etc., may be used.

After the electric wire fixing step, the connecting step is performed.FIG.8is a plan view showing the electronic component2, three conductive bonding materials6, the three electric wires3, and the core wire fixing member4after the connecting step. In the connecting step, the three core wire exposed portions302are connected to the three electrodes21using the conductive bonding materials6. In the first embodiment, first, a solder paste to be the conductive bonding material6is placed on each of the three electrodes21of the electronic component2in the connecting step. Then, the three core wire exposed portions302are positioned to respectively face the three electrodes21and are brought into contact with the solder pastes respectively placed on the three electrodes21. The solder pastes are then melted and hardened by reflowing at a temperature of about 300° C. as an example, thereby forming the conductive bonding materials6that mechanically and electrically connect the three core wire exposed portions302to the three electrodes21. The material of the core wire fixing member4is selected so that the core wire fixing member4can withstand the high temperature environment at this time.

After the connecting step, the sealing step is performed. In the sealing step, the three electrodes21, the three core wire exposed portions302, the tip portions of the three covered portions301and the core wire fixing member4are covered with a molten resin to be the sealing material5and the molten resin is then hardened, thereby forming the sealing material5as shown inFIGS.2to4.

The electric wire connection structure1in the first embodiment can be manufactured as described above.

Functions and Effects of the First Embodiment

The electric wire connection structure1in the first embodiment includes the core wire fixing member4that fixes the plural core wire exposed portions302to each other. Therefore, it is easy to maintain the distances between the plural core wire exposed portions302. This suppresses contact and conduction between the core wire exposed portions302due to, e.g., deformation of the core wire exposed portions302during the manufacturing process.

In addition, the core wire fixing member4is formed by hardening a molten resin filling around the plural core wire exposed portions302and is in contact with the tip end surfaces321of the plural coverings32. Therefore, the molten resin to be the core wire fixing member4easily spreads along the tip end surfaces321of the plural coverings32and is easily formed in a bulk shape. The bulk shape of the core wire fixing member4increases the strength of the core wire fixing member4and suppresses separation of the core wire exposed portions302from the core wire fixing member4.

In addition, the electric wire connection structure1in the first embodiment further includes the sealing material5that seals the plural electrodes21, the tip portions of the plural electric wires3and the core wire fixing member4. Therefore, e.g., ingress of moisture, etc. to the plural electrodes21and the plural electric wires3is suppressed. In addition, separately forming the core wire fixing member4and the sealing material5increases the degrees of freedom in selecting the materials thereof. For example, a material which is adhesive to the portions to be sealed (in the first embodiment, the three electrodes21, the core wires31and the coverings32of the three electric wires3, and the core wire fixing member4) can be selected as the sealing material5, while a material which does not have such adhesive properties can be used as the core wire fixing member4.

In addition, at least a portion of the core wire fixing member4is arranged on the side where the tip end surfaces321of the coverings32are located, relative to the center position C between the electronic component2and the tip end surfaces321of the coverings32in the axial direction X. As a result, an impact (e.g., thermal or mechanical impact, etc.) on the core wire fixing member4at the time of connecting the electrodes21to the core wire exposed portions302can be suppressed without increasing the length L in the axial direction X from the tip end surfaces321of the coverings32of the three electric wires3to the electronic component2. This reduces the sealing area of the sealing material5, thereby reducing the overall weight of the electric wire connection structure1and simplifying the sealing step of forming the sealing material5.

In addition, the coverings32are made of a fluorine-based resin, and the sealing material5seals up to the tip portions of the coverings32and is made of a material that is adhesive to the fluorine-based resin. Materials which can adhere to fluorine-based resins are limited. However, in the first embodiment, since ingress of moisture to, e.g., the plural electrodes21and the conductive portions of the plural electric wires3through the interface between the coverings32and the sealing material5is suppressed, the core wire fixing member4is not necessarily required to have adhesion to the portions to be in contact therewith, which increases the degrees of freedom in selecting the material.

In addition, the core wire fixing member4is formed in a bulk shape with the thickness T of not less than the diameter D of the core wire31. This increases the strength of the core wire fixing member4, resulting in that separation of the core wire exposed portions302from the core wire fixing member4due to cracking, etc., of the core wire fixing member4is suppressed.

In addition, the plural core wire exposed portions302are respectively connected to the plural electrodes21using the conductive bonding materials6that melt and harden with temperature change. This is a condition in which the core wire fixing member4is affected by thermal changes at the time of connecting the core wire exposed portions302to the electrodes21and thermal stress is likely to be generated. However, in the first embodiment, since the core wire fixing member4is formed in a bulk shape, separation of the core wire exposed portions302from the core wire fixing member4due to thermal stress is suppressed.

In addition, in the first embodiment, the electric wire connection structure1is used for a medical device that is inserted into the body. That is, each component constituting the electric wire connection structure1needs to be extremely small so that the medical device including the electric wire connection structure I can be inserted into the body. In such a case, it is extremely difficult to maintain the distances between the plural core wire exposed portions302. However, the electric wire connection structure1in the first embodiment can be suitably used since the distances between the plural core wire exposed portions302can be maintained by using the core wire fixing member4as described above.

In addition, the method for manufacturing the electric wire connection structure1in the first embodiment includes the electric wire fixing step in which the core wire exposed portions302of the plural electric wires3, at which the core wires31are exposed from the coverings32, are arranged in parallel and fixed by the core wire fixing member4, and the connecting step which is performed after the electric wire fixing step and in which the core wire exposed portions302of the plural electric wires3are respectively connected to the plural electrodes21of the electronic component2. In this way, the core wire exposed portions302can be aligned with the plural electrodes21in the state in which the distances between the plural core wire exposed portions302are fixed by the core wire fixing member4, hence, productivity of the electric wire connection structure1is improved.

As described above, according to the first embodiment, it is possible to provide an electric wire connection structure in which the distances between plural core wire exposed portions are easily maintained, and a method for manufacturing an electric wire connection structure.

Second Embodiment

The second embodiment of the invention will be described in reference toFIG.9.FIG.9is a cross-sectional view showing the electric wire connection structure1taken parallel to the axial direction X and the height direction Z.

In the second embodiment, the relative positions of the core wire fixing member4and the coverings32are changed from those in the first embodiment. In particular, the core wire fixing member4is arranged at a distance from the tip end surfaces321of the coverings32of the three electric wires3. Also in the second embodiment, the core wire fixing member4is arranged on the side where the tip end surfaces321of the coverings32are located, relative to the center position C between the electronic component2and the tip end surfaces321of the coverings32in the axial direction X. The core wire fixing member4covers only the three core wire exposed portions302. The space between the core wire fixing member4and the tip end surfaces321of the coverings32of the three electric wires3is filled with the sealing material5.

The other configurations in the second embodiment are the same as in the first embodiment.

Among the reference signs used in the second embodiment onwards, the same reference signs as those used in the already-described embodiment indicate the same constituent elements, etc., as those in the already-described embodiment, unless otherwise specified.

Functions and Effects of the Second Embodiment

In the second embodiment, the core wire fixing member4is located at a distance from the tip end surfaces321of the coverings32, and the space between the core wire fixing member4and the tip end surfaces321of the coverings32of the plural electric wires3is filled with the sealing material5. Since the sealing material5which is adhesive to the coverings32is arranged also on the tip end surfaces321of the coverings32, reaching of moisture to the conductive portions of the plural electric wires3through between the sealing material5and the coverings32is suppressed.

The second embodiment also has the same functions and effects as those in the first embodiment.

Summary of the embodiments

Technical ideas understood from the embodiments will be described below citing the reference signs, etc., used for the embodiments. However, each reference sign, etc. described below is not intended to limit the constituent elements in the claims to the members, etc., specifically described in the embodiments.

According to the first feature, an electric wire connection structure1includes a plurality of electric wires3each including a covered portion301, at which a core wire31is covered with a covering32, and a core wire exposed portion302, at which the core wire31is exposed from the covering32, the exposed core wire portions302being arranged in parallel to each other; an electronic component2includes a plurality of electrodes21respectively connected to the core wire exposed portions302of the plurality of electric wires3; and a core wire fixing member4to fix the plurality of core wire exposed portions302to each other.

According to the second feature, in the electric wire connection structure1as described by the first feature, the core wire fixing member4is formed by hardening a molten resin filling around the plurality of core wire exposed portions302and is in contact with a tip end surface321of the covering32of at least one of the plurality of electric wires3.

According to the third feature, the electric wire connection structure1as described by the first or second feature further includes a sealing material5to seal the plurality of electrodes21, tip portions of the plurality of electric wires3, and the core wire fixing member4.

According to the fourth feature, in the electric wire connection structure1as described by the third feature, at least a portion of the core wire fixing member4is arranged on the tip end surface321side relative to a center position C between the electronic component2and the tip end surface321of the covering32in a longitudinal direction X of each of the core wire exposed portions302.

According to the fifth feature, in the electric wire connection structure1as described by the third or fourth feature, the covering32includes a fluorine-based resin, and the sealing material5seals up to tip portions of the coverings32of the plurality of electric wires3and includes a material that is adhesive to the fluorine-based resin.

According to the sixth feature, in the electric wire connection structure1as described by the fifth feature, the core wire fixing member4is located at a distance from the tip end surfaces321of the coverings32of the plurality of electric wires3, and a space between the core wire fixing member4and the tip end surfaces321of the coverings32of the plurality of electric wires3is filled with the sealing material5.

According to the seventh feature, in the electric wire connection structure1as described by any one of the first to sixth features, the core wire fixing member4is formed in a bulk shape with a thickness T of not less than a diameter D of the core wire31.

According to the eighth feature, in the electric wire connection structure1as described by the seventh feature, the plurality of core wire exposed portions302are respectively connected to the plurality of electrodes21using a conductive bonding material6that melts and hardens with temperature change.

According to the ninth feature, the electric wire connection structure1as described by any one of the first to eighth features is used for a medical device that is inserted into the body.

According to the tenth feature, a method for manufacturing an electric wire connection structure1includes arranging in parallel core wire exposed portions302of a plurality of electric wires3at which core wires31are exposed from coverings32, and fixing the core wire exposed portions302with a core wire fixing member4, thereby fixing electric wires; and after the fixing electric wires, connecting the core wire exposed portions302of the plurality of electric wires3respectively to a plurality of electrodes21of an electronic component2.

Although the embodiments of the invention have been described, the invention according to claims is not to be limited to the embodiments described above. Further, please note that not all combinations of the features described in the embodiments are necessary to solve the problem of the invention. In addition, the invention can be appropriately modified and implemented without departing from the gist thereof.