Medical device and method for manufacturing medical device

Abstract

This medical device comprises: a first component that contains a first metal element; a second component; and a joining part that joins the first component and the second component. The joining part includes a second metal element. The joining part has a film, containing the second metal element, on a surface of the joining part.

Description

Medical device and method for manufacturing the same

[0001] TECHNICAL FIELD The technology disclosed herein relates to medical devices and methods for manufacturing medical devices.

[0002] The guidewire includes a coil, a core shaft, and a joint portion that joins the coil and the core shaft. A known guidewire has a coating on the surface of the coil to improve corrosion resistance (see, for example, Patent Document 1).

[0003] Japanese Patent Application Publication No. 6-81547

[0004] The coil includes a first metal element (e.g., platinum (Pt)). The joint includes a second metal element (e.g., tin (Sn)) different from the first metal element. In a guidewire having such a configuration, a redox reaction occurs due to a metal potential difference, which may cause corrosion at the joint.

[0005] This specification discloses a technique that can solve the above-mentioned problems.

[0006] The technology disclosed in this specification can be realized, for example, in the following forms.

[0007] (1) A medical device disclosed herein includes a first component containing a first metal element, a second component, and a joint that joins the first component and the second component. The joint contains the second metal element. The joint has a coating containing the second metal element on the surface of the joint. The coating formed on the surface of the joint suppresses a redox reaction caused by a metal potential difference between the first metal element and the second metal element. As a result, the corrosion resistance of the joint is improved.

[0008] (2) In the medical device, the ionization tendency of the second metal element may be greater than the ionization tendency of the first metal element. The coating improves the corrosion resistance of the joint containing an element with a relatively high ionization tendency.

[0009] (3) In the medical device, the second metal element may be tin. The coating improves the corrosion resistance of the joint containing tin, which is an element with a relatively high ionization tendency.

[0010] (4) In the medical device, the joint may include tin-silver solder, and the coating improves the corrosion resistance of the joint including tin-silver solder containing tin, an element with a relatively high ionization tendency.

[0011] (5) In the medical device, the coating may be a phosphate coating, which improves corrosion resistance of the joint.

[0012] (6) In the above medical device, the coating is Sn ３ (P.O. ４ ) ２ It may contain Sn ３ (P.O. ４ ) ２ The coating containing improves the corrosion resistance of the joint.

[0013] (7) In the medical device, the coating may be a black coating, which inhibits discoloration of the joint.

[0014] (8) In the above medical device, the first component may be a coil. A coating formed on a surface of a joint for joining the coil improves corrosion resistance of the joint.

[0015] (9) In the medical device, the coil may be a first coil, and the medical device may further include a second coil covering the first coil. A coating formed on the surface of a joint for joining the inner layer coil improves corrosion resistance of the joint.

[0016] (10) In the above medical device, the joint is a first joint, and the medical device further includes a second joint that joins the second coil and the second component, and the second joint may include gold-tin solder.

[0017] (11) The method for manufacturing a medical device disclosed in this specification includes joining a first part containing a first metal element and a second part with a joint containing a second metal element, and forming a coating containing the second metal element on the surface of the joint.

[0018] (12) In the above-described method for manufacturing a medical device, the ionization tendency of the second metal element may be greater than the ionization tendency of the first metal element.

[0019] (13) In the above method for manufacturing a medical device, the second metal element may be tin.

[0020] (14) In the above-described method for manufacturing a medical device, the joint may include tin-silver solder.

[0021] (15) In the above method for manufacturing a medical device, the coating may be a phosphate coating.

[0022] (16) In the method for producing a medical device, the coating is formed of Sn ３ (P.O. ４ ) ２ may include:

[0023] (17) In the above-mentioned method for manufacturing a medical device, the coating may be a black coating.

[0024] (18) In the method for manufacturing a medical device, the coating may be formed on the surface of the joint by immersing the joint in an aqueous solution containing phosphoric acid. According to this method, the coating is formed on the surface of the joint reliably and efficiently.

[0025] (19) In the above-described method for manufacturing a medical device, the first part may be a coil.

[0026] (20) In the above-mentioned method for manufacturing a medical device, the coil may be a first coil, the joint may be a first joint, and a second coil covering the first coil and the second component may be joined by a second joint including gold-tin solder.

[0027] FIG. 1 is an explanatory diagram showing a longitudinal section (YZ section) of a guide wire in the first embodiment; FIG. 2 is a flowchart showing a method for manufacturing a guide wire in the first embodiment; FIG. 3 is an explanatory diagram showing a method for forming a coating on the surface of a joint; FIG. 4 is an explanatory diagram showing a longitudinal section (YZ section) of a guide wire in the second embodiment; and FIG. 5 is an explanatory diagram showing the performance evaluation results for corrosion resistance of a joint.

[0028] First Embodiment Fig. 1 is an explanatory diagram showing a longitudinal section (YZ section) of a guidewire 100 in a first embodiment. In Fig. 1, a portion of the guidewire 100 is not shown. Fig. 1 shows the guidewire 100 in a linear state parallel to the Z axis. The guidewire 100 is flexible enough to be bent.

[0029] In the guidewire 100, the positive Z-axis direction is the tip side (distal side) that is inserted into the body, and the negative Z-axis direction is the base side (proximal side) that is manipulated by the operator. In this specification, for the guidewire 100 and each of its components, the tip side is referred to as the "tip," the tip and its vicinity are referred to as the "tip portion," the base side is referred to as the "base end," and the base end and its vicinity are referred to as the "base portion." The transverse cross section of the guidewire 100 and each of its components refers to a cross section perpendicular to the longitudinal direction. The longitudinal cross section of the guidewire 100 and each of its components refers to a cross section parallel to the longitudinal central axis. For the guidewire 100 and each of its components, the direction perpendicular to the longitudinal central axis is referred to as the radial direction. The outer diameter of the guidewire 100 and each of its components refers to the width along the radial direction.

[0030] The guidewire 100 is a medical device that is inserted into a body lumen such as a blood vessel. The total length of the guidewire 100 is, for example, 1000 mm or more and 3000 mm or less.

[0031] The guidewire 100 includes a core shaft 10 , a coil 20 , a distal joint 30 , and a proximal joint 40 .

[0032] The core shaft 10 is an elongated member. The core shaft 10 includes a thin diameter portion 11, a thick diameter portion 15, and a tapered portion 14. The thin diameter portion 11 is a rod-shaped portion having a substantially constant outer diameter. The tip of the thin diameter portion 11 coincides with the tip of the core shaft 10. The thick diameter portion 15 is located closer to the base end than the thin diameter portion 11 and is a rod-shaped portion having a substantially constant outer diameter larger than the outer diameter of the thin diameter portion 11. The outer diameter of the thick diameter portion 15 is, for example, 0.2 mm or more and 3.0 mm or less. The tapered portion 14 is located between the thin diameter portion 11 and the thick diameter portion 15 and is a portion whose outer diameter gradually increases from the boundary with the thin diameter portion 11 toward the boundary with the thick diameter portion 15. The cross-sectional shape at each position of the core shaft 10 can be any shape. The cross-sectional shape at each position of the core shaft 10 may be, for example, a circle, a partial circle, an ellipse, a rectangle, a parallelogram, a trapezoid, a rhombus, or the like. The cross-sectional shape may be different at different positions along the longitudinal direction of the core shaft 10 .

[0033] The core shaft 10 is made of, for example, a metal. More specifically, stainless steel (SUS302, SUS304, SUS316, etc.), Ni-Ti alloy, piano wire, etc. may be used. The core shaft 10 may be made entirely of the same material, or may be made of different materials in different sections. The core shaft 10 is an example of a second component.

[0034] The coil 20 is a hollow cylindrical member in which one or more wires are wound in a spiral shape. The core shaft 10 is inserted into the hollow portion of the coil 20. In this embodiment, the coil 20 is arranged so as to cover a portion of the small diameter portion 11, the tapered portion 14, and a portion of the large diameter portion 15 of the core shaft 10. The total length of the coil 20 is, for example, 10 mm or more and 500 mm or less. The outer diameter of the coil 20 is, for example, 0.1 mm or more and 2.0 mm or less. In this embodiment, the outer diameter of the coil 20 is constant throughout the entire length of the coil 20. The coil 20 may have a portion whose outer diameter changes along the longitudinal direction. In this embodiment, there are no other coils located outside the coil 20. That is, the coil 20 is an outer layer coil.

[0035] The coil 20 is formed from, for example, a metal. More specifically, radiotransparent materials such as stainless steel (SUS302, SUS304, SUS316, etc.), Ni-Ti alloys, and piano wire, as well as radiopaque materials such as platinum, gold, tungsten, and alloys thereof, are used. The coil 20 may be formed entirely from the same material, or portions may be formed from different materials. The coil 20 is an example of a first component. A specific element (e.g., platinum (Pt)) included in the material forming the coil 20 is an example of a first metal element. Platinum is radiopaque. The first metal element of this embodiment is radiopaque.

[0036] The distal joint 30 joins the distal end of the core shaft 10 and the distal end of the coil 20. The distal joint 30 is also called a distal tip. The distal end of the distal joint 30 coincides with the distal end of the guidewire 100. The distal outer peripheral surface of the distal side of the distal joint 30 is a smooth surface (e.g., a substantially hemispherical or cylindrical surface). The proximal joint 40 joins the core shaft 10 and the proximal end of the coil 20. The distal joint 30 and the proximal joint 40 are also collectively called joints 30, 40.

[0037] Examples of materials used to form the joints 30, 40 include metal solders (gold-tin solder, tin-silver solder, tin-lead solder, lead-silver solder, etc.), brazing materials (aluminum alloy brazing, silver brazing, gold brazing, etc.), and adhesives (epoxy adhesives, etc.). The materials used to form the distal joint 30 and the proximal joint 40 may be the same or different. In this embodiment, tin-silver solder is used to form the joints 30, 40. That is, the joints 30, 40 contain tin (Sn). Tin is an element with a relatively high ionization tendency. The ionization tendency of tin is greater than the ionization tendency of a specific element (e.g., Pt) contained in the material forming the coil 20. At least one of the distal joint 30 and the proximal joint 40 is an example of a joint. Tin is an example of a second metal element.

[0038] A distal coating 32 is formed on the surface of the distal joint 30. A proximal coating 42 is formed on the surface of the proximal joint 40. The distal coating 32 and the proximal coating 42 are also collectively referred to as coatings 32, 42. For convenience, the coatings 32, 42 are shown by dashed lines in FIG. 1. The coatings 32, 42 contain the same elements as those contained in the joints 30, 40. In this embodiment, the coatings 32, 42 contain tin. The coatings 32, 42 are, for example, phosphate coatings (chemical coatings). The coatings 32, 42 are, for example, Sn ３ (P.O. ４ ) ２ The coatings 32 and 42 are, for example, black coatings.

[0039] 2 is a flowchart showing a method for manufacturing the guidewire 100 according to the first embodiment. First, an operator joins the core shaft 10 and the coil 20 at the joints 30, 40 (S110). The operator forms the joints 30, 40 by soldering using, for example, tin-silver solder.

[0040] Next, the worker forms the coatings 32, 42 on the surfaces of the joints 30, 40 (S120). FIG. 3 is an explanatory diagram showing a method for forming the coatings 32, 42 on the surfaces of the joints 30, 40. FIG. 3 shows a container 200 containing an aqueous solution 210 containing phosphoric acid. The worker immerses the joints 30, 40 in the aqueous solution 210 containing phosphoric acid. This causes an oxidation reaction (a reaction in which tin becomes tin ions) on the surfaces of the joints 30, 40, and a reduction reaction on the surface of the coil 20. As a result, for example, as shown in the following reaction formula (1), the tin ions react with the phosphoric acid contained in the aqueous solution 210 to form Sn ３ (P.O. ４ ) ２ The concentration of the aqueous solution 210 containing phosphoric acid and the immersion time are appropriately set depending on the properties of the coatings 32, 42 to be formed. The guidewire 100 of this embodiment is mainly manufactured by the above-mentioned method.

[0041] Effect of First Embodiment As described above, the guidewire 100 of this embodiment includes the coil 20 containing a first metal element (e.g., Pt), the core shaft 10, and joints 30, 40 that join the coil 20 and the core shaft 10. The joints 30, 40 contain a second metal element (e.g., tin). Coatings 32, 42 containing the second metal element are formed on the surfaces of the joints 30, 40. In the guidewire 100 of this embodiment, the presence of the coatings 32, 42 formed on the surfaces of the joints 30, 40 can suppress an oxidation-reduction reaction caused by a metal potential difference between the first metal element and the second metal element, and as a result, the corrosion resistance of the joints 30, 40 can be improved.

[0042] In the guidewire 100 of this embodiment, the ionization tendency of the second metallic element is greater than the ionization tendency of the first metallic element. According to the guidewire 100 of this embodiment, in a configuration in which the joints 30, 40 are susceptible to corrosion because they contain an element with a relatively high ionization tendency, the presence of the coatings 32, 42 can improve the corrosion resistance of the joints 30, 40.

[0043] In the guidewire 100 of this embodiment, the second metallic element is tin. In the guidewire 100 of this embodiment, the joints 30, 40 contain tin, an element with a relatively high ionization tendency, and therefore are susceptible to corrosion. However, the presence of the coatings 32, 42 can improve the corrosion resistance of the joints 30, 40.

[0044] In the guidewire 100 of this embodiment, the joints 30, 40 contain tin-silver solder. According to the guidewire 100 of this embodiment, the joints 30, 40 contain tin-silver solder containing tin, an element with a relatively high ionization tendency, and therefore are susceptible to corrosion. In this configuration, the presence of the coatings 32, 42 can improve the corrosion resistance of the joints 30, 40.

[0045] In the guide wire 100 of this embodiment, the coatings 32, 42 are phosphate coatings. According to the guide wire 100 of this embodiment, the presence of the coatings 32, 42, which are phosphate coatings, can effectively improve the corrosion resistance of the joints 30, 40.

[0046] In the guide wire 100 of this embodiment, the coatings 32 and 42 are made of Sn ３ (P.O. ４ ) ２ According to the guide wire 100 of this embodiment, Sn ３ (P.O. ４ ) ２ The presence of the coatings 32, 42 containing the above can effectively improve the corrosion resistance of the joints 30, 40.

[0047] In the guidewire 100 of this embodiment, the coatings 32, 42 are black coatings. According to the guidewire 100 of this embodiment, the coatings 32, 42 can suppress discoloration of the bonded portions 30, 40.

[0048] In the method for manufacturing the guidewire 100 of this embodiment, the coil 20 containing a first metal element (e.g., Pt) and the core shaft 10 are joined by joints 30, 40 containing a second metal element (e.g., tin), and coatings 32, 42 containing the second metal element are formed on the surfaces of the joints 30, 40. According to the method for manufacturing the guidewire 100 of this embodiment, the coatings 32, 42 containing the second metal element can be formed on the surfaces of the joints 30, 40, and the corrosion resistance of the joints 30, 40 can be improved.

[0049] In the method for manufacturing guidewire 100 of the present embodiment, bonding portions 30, 40 are immersed in aqueous solution 210 containing phosphoric acid to form coatings 32, 42 on the surfaces of bonding portions 30, 40. According to the method for manufacturing guidewire 100 of the present embodiment, coatings 32, 42 can be formed on the surfaces of bonding portions 30, 40 reliably and efficiently.

[0050] Second Embodiment Fig. 4 is an explanatory diagram showing a longitudinal cross section (YZ cross section) of a guidewire 100a according to a second embodiment. In the following, among the configuration of the guidewire 100a of the second embodiment, the same configuration as that of the guidewire 100 of the first embodiment described above will be denoted by the same reference numerals, and description thereof will be omitted as appropriate.

[0051] The guide wire 100a of the second embodiment includes a core shaft 10, a coil 20, a distal joint 30, a proximal joint 40, an inner layer coil 50, a distal inner layer joint 60, and a proximal inner layer joint 70.

[0052] The core shaft 10 includes a thin diameter portion 11, a thick diameter portion 15, a tapered portion 14, an intermediate diameter portion 13, and a distal tapered portion 12. The intermediate diameter portion 13 is located between the thin diameter portion 11 and the thick diameter portion 15 and is a rod-shaped portion having a substantially constant outer diameter that is larger than the outer diameter of the thin diameter portion 11 and smaller than the outer diameter of the thick diameter portion 15. The distal tapered portion 12 is located between the thin diameter portion 11 and the intermediate diameter portion 13 and is a portion whose outer diameter gradually increases from the boundary with the thin diameter portion 11 toward the boundary with the intermediate diameter portion 13. The tapered portion 14 is located between the intermediate diameter portion 13 and the thick diameter portion 15 and is a portion whose outer diameter gradually increases from the boundary with the intermediate diameter portion 13 toward the boundary with the thick diameter portion 15. The core shaft 10 is an example of a second component.

[0053] The inner layer coil 50 is a hollow cylindrical member in which one or more wires are wound in a spiral shape. The core shaft 10 is inserted into the hollow portion of the inner layer coil 50. In this embodiment, the inner layer coil 50 is arranged so as to cover a part of the small diameter portion 11, the distal tapered portion 12, and a part of the intermediate diameter portion 13 of the core shaft 10. The distal end of the inner layer coil 50 is located closer to the base end than the distal end of the core shaft 10. The coil 20 is arranged so as to cover the inner layer coil 50. The inner layer coil 50 is an example of a first component and a first coil. The coil 20 is an example of a second coil.

[0054] The inner layer coil 50 is formed from, for example, a metal. More specifically, radiotransparent materials such as stainless steel (SUS302, SUS304, SUS316, etc.), Ni-Ti alloys, and piano wire, as well as radiopaque materials such as platinum, gold, tungsten, and alloys thereof, are used. The inner layer coil 50 may be formed entirely from the same material, or may be formed in sections from different materials. A specific element (e.g., Pt) contained in the material forming the inner layer coil 50 is an example of a first metal element.

[0055] The distal joint 30 joins the distal end of the core shaft 10 to the distal end of the coil 20. The proximal joint 40 joins the core shaft 10 to the proximal end of the coil 20. The distal joint 30 and the proximal joint 40 are also collectively referred to as joints 30, 40. In this embodiment, gold-tin solder is used as the material for forming the joints 30, 40. The joints 30, 40 are an example of a second joint.

[0056] The distal inner layer joint 60 joins the core shaft 10 to the distal end of the inner layer coil 50. The proximal inner layer joint 70 joins the core shaft 10 to the proximal end of the inner layer coil 50. The distal inner layer joint 60 and the proximal inner layer joint 70 are also collectively referred to as the inner layer joints 60, 70.

[0057] Examples of materials used to form the inner layer joints 60, 70 include metal solders (gold-tin solder, tin-silver solder, tin-lead solder, lead-silver solder, etc.), brazing materials (aluminum alloy brazing, silver brazing, gold brazing, etc.), and adhesives (epoxy adhesives, etc.). The materials used to form the distal inner layer joint 60 and the proximal inner layer joint 70 may be the same or different. In this embodiment, tin-silver solder is used to form the inner layer joints 60, 70. That is, the inner layer joints 60, 70 contain tin. The ionization tendency of tin is greater than the ionization tendency of a specific element (e.g., Pt) contained in the material forming the inner layer coil 50. At least one of the distal inner layer joint 60 and the proximal inner layer joint 70 is an example of a joint and a first joint. Tin is an example of a second metal element.

[0058] A distal inner layer coating 62 is formed on the surface of the distal inner layer joint 60. A proximal inner layer coating 72 is formed on the surface of the proximal inner layer joint 70. The distal inner layer coating 62 and the proximal inner layer coating 72 are also collectively referred to as inner layer coatings 62, 72. The inner layer coatings 62, 72 contain the same elements as those contained in the inner layer joints 60, 70. In this embodiment, the inner layer coatings 62, 72 contain tin. The inner layer coatings 62, 72 are, for example, phosphate coatings. The inner layer coatings 62, 72 are, for example, Sn ３ (P.O. ４ ) ２ The inner coatings 62 and 72 are, for example, black coatings.

[0059] As described above, the guidewire 100a of the second embodiment includes the inner layer coil 50 containing a first metal element (e.g., Pt), the core shaft 10, and inner layer joints 60, 70 joining the inner layer coil 50 and the core shaft 10. The inner layer joints 60, 70 contain a second metal element (e.g., tin). An inner layer coating 62, 72 containing the second metal element is formed on the surface of the inner layer joint 60, 70. According to the guidewire 100a of the present embodiment, the presence of the inner layer coating 62, 72 formed on the surface of the inner layer joint 60, 70 can suppress an oxidation-reduction reaction caused by a metal potential difference between the first metal element and the second metal element, thereby improving the corrosion resistance of the inner layer joints 60, 70.

[0060] The guidewire 100a of the second embodiment further includes joints 30, 40 that join the coil 20 and the core shaft 10, and the joints 30, 40 contain gold-tin solder. According to the guidewire 100a of the present embodiment, the corrosion resistance of the joints 30, 40 can be improved by using gold-tin solder, and the corrosion resistance of the inner layer joints 60, 70 can be improved by using inner layer coatings 62, 72.

[0061] 5 is an explanatory diagram showing the results of a performance evaluation of the corrosion resistance of the bonded portions. In this performance evaluation, a corrosion resistance test was conducted in accordance with ISO 11070:2014 A1:2018, 4.4 and Annex B on a sample (Example) in which the coatings 32, 42 were formed at the bonded portions 30, 40 in the configuration of the guide wire 100 of the first embodiment described above, and a sample (Comparative Example) in which the coatings 32, 42 were not formed at the bonded portions 30, 40.

[0062] As shown in Figure 5, before the corrosion resistance test, no corrosion was observed at the joints in both the Example and the Comparative Example. After the corrosion resistance test, no corrosion was observed at the joints in the Example. After the corrosion resistance test, corrosion was observed at the joints in the Comparative Example. These performance evaluation results confirmed that the presence of the coatings 32, 42 on the surfaces of the joints 30, 40 improves the corrosion resistance of the joints 30, 40.

[0063] (Modifications) The technology disclosed in this specification is not limited to the above-described embodiments, and can be modified into various forms without departing from the spirit thereof, for example, the following modifications are also possible.

[0064] In the above embodiments, the materials forming the joints and the coating are merely examples and can be modified in various ways. For example, in the above embodiments, the second metal element contained in the joints and the coating may be an element other than tin, such as zinc. In the above embodiments, the material forming the joints may be a material other than solder, such as brazing material. In the above embodiments, the coating may be a coating other than a phosphate coating, such as an oxide coating of tin oxide or zinc oxide.

[0065] In the first embodiment, the core shaft 10 and the coil 20 may be joined by a joint other than the distal joint 30 and the proximal joint 40. In this case, a coating similar to the coatings 32, 42 may be formed on the other joint.

[0066] In the second embodiment, the core shaft 10a and the inner layer coil 50 may be joined by a joint other than the distal inner layer joint 60 and the proximal inner layer joint 70. In this case, a coating similar to the inner layer coatings 62, 72 may be formed at the other joint.

[0067] In the second embodiment, the bonding portions 30, 40 may contain a second metal element (for example, tin), and the coatings 32, 42 containing the second metal element may be formed on the surfaces of the bonding portions 30, 40.

[0068] For example, the coatings 32, 42 may be formed on the surfaces of the joints 30, 40 by applying an aqueous solution 210 containing phosphoric acid to the joints 30, 40.

Claims

1. A medical device (100, 100a) comprising: a first part (20, 50) containing a first metal element; a second part (10); and a joining part (30, 40, 60, 70) containing a second metal element and joining the first part (20, 50) and the second part (10), the joining part (30, 40, 60, 70) having a coating (32, 42, 62, 72) containing the second metal element on the surface of the joining part (30, 40, 60, 70).

2. A medical device (100, 100a) according to claim 1, wherein the ionization tendency of the second metal element is greater than the ionization tendency of the first metal element.

3. A medical device (100, 100a) according to claim 1 or claim 2, wherein the second metal element is tin.

4. A medical device (100, 100a) according to any one of claims 1 to 3, wherein the joint (30, 40, 60, 70) comprises tin-silver solder.

5. A medical device (100, 100a) according to any one of claims 1 to 4, wherein the coating (32, 42, 62, 72) is a phosphate coating.

6. A medical device (100, 100a) according to any one of claims 1 to 5, wherein the coating (32, 42, 62, 72) is Sn ３ (P.O. ４ ) ２ A medical device (100, 100a).

7. A medical device (100, 100a) according to any one of claims 1 to 6, wherein the coating (32, 42, 62, 72) is a black coating.

8. A medical device (100, 100a) according to any one of claims 1 to 7, wherein the first part (20, 50) is a coil (20, 50).

9. A medical device (100a) according to claim 8, wherein the coil (50) is a first coil (50), and the medical device (100a) further comprises a second coil (20) covering the first coil (50).

10. A medical device (100a) according to claim 9, wherein the joint (60, 70) is a first joint (60, 70), and the medical device (100a) further comprises a second joint (30, 40) joining the second coil (20) and the second component (10), and the second joint (30, 40) comprises gold-tin solder.

11. A method for manufacturing a medical device (100, 100a), comprising joining a first component (20, 50) containing a first metal element to a second component (10) by a joining portion (30, 40, 60, 70) containing a second metal element, and forming a coating (32, 42, 62, 72) containing the second metal element on the surface of the joining portion (30, 40, 60, 70).

12. A method for manufacturing a medical device (100, 100a) according to claim 11, wherein the ionization tendency of the second metal element is greater than the ionization tendency of the first metal element.

13. A method for manufacturing a medical device (100, 100a) according to claim 11 or 12, wherein the second metal element is tin.

14. A method for manufacturing a medical device (100, 100a) according to any one of claims 11 to 13, wherein the joint (30, 40, 60, 70) comprises tin-silver solder.

15. A method for manufacturing a medical device (100, 100a) according to any one of claims 11 to 14, wherein the coating (32, 42, 62, 72) is a phosphate coating.

16. A method for manufacturing a medical device (100, 100a) according to any one of claims 11 to 15, wherein the coating (32, 42, 62, 72) is made of Sn ３ (P.O. ４ ) ２ A method for manufacturing a medical device (100, 100a), comprising:

17. A method for manufacturing a medical device (100, 100a) according to any one of claims 11 to 16, wherein the coating (32, 42, 62, 72) is a black coating.

18. A method for manufacturing a medical device (100, 100a) according to any one of claims 11 to 17, comprising forming the coating (32, 42, 62, 72) on the surface of the joint (30, 40, 60, 70) by immersing the joint (30, 40, 60, 70) in an aqueous solution (210) containing phosphoric acid.

19. A method for manufacturing a medical device (100, 100a) according to any one of claims 11 to 18, wherein the first part (20, 50) is a coil (20, 50).

20. A method for manufacturing a medical device (100a) according to claim 19, wherein the coil (50) is a first coil (50), the joint (60, 70) is a first joint (60, 70), and a second coil (20) covering the first coil (50) and the second component (10) are joined by a second joint (30, 40) containing gold-tin solder.

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