JP7575775B2 - Manufacturing method of conductive part, manufacturing method of electronic component including conductive part, manufacturing method of product assembled with electronic components including conductive part, conductive part, electronic component having conductive part, product incorporating electronic component including conductive part - Google Patents

Description

The present invention relates to a method for manufacturing a conductive structure using fired metal ink and the conductive structure.

Electronic components are made on a substrate with conductors as conductor wires. There are many different types of conductor materials, but titanium, aluminum, and their alloys, which form a nanometer-order natural oxide layer on the surface of the conductor, are sometimes used as conductor materials. These metals are very susceptible to oxidation in the atmosphere, forming a natural oxide layer. The natural oxide layer is an insulator, and all parts that come into contact with the atmosphere are covered with the natural oxide layer. In addition, as in Patent Document 2, an insulating layer such as SiO, SiN, or SiON may be formed by plasma CVD on a wiring layer such as aluminum instead of the natural oxide layer. Even if an attempt is made to pass electricity between a wiring or electrode that has a natural oxide layer or insulating layer on its surface by overlapping another wiring, the natural oxide layer or insulating layer will prevent electricity from passing between them by simply overlapping them (it will not become a conductive part).
Therefore, as described in Patent Document 1, a method is also used in which the native oxide layer is physically destroyed by scratching it with a polishing needle, and another conductor is then layered on top of it to form a conductive portion.

JP 2000-22306 A Patent No. 6711614

However, physical operations such as scratching with a polishing needle become more difficult as the conductor becomes thinner, and workability deteriorates. Moreover, even if the natural oxide layer is destroyed and the metal is exposed, titanium and aluminum are easily oxidized in the atmosphere, and the natural oxide layer forms again in an extremely short time. For this reason, it has been difficult to form a conductive part with reliable conductivity.
The same applies to the insulating layer that covers the surface of the metal wiring, and when overlapping another wiring, it is necessary to remove the insulating layer beforehand.

The present invention aims to provide a manufacturing method for easily creating a conductive portion between a conductor having an insulating layer on its surface and another conductor, and to provide a new conductive portion.

The present invention solves this problem by providing a method for manufacturing a conductive part, which includes a first step of stacking a second conductor on a first conductor having an insulating layer on its surface, and a second step of melting the first conductor and the second conductor, including the insulating layer, to create a molten region and forming a hole in the center of the molten region that is surrounded by the molten region.

In another aspect of the present invention, the problem is solved by providing a conductive part that includes a first conductor, a second conductor, and a molten region, the first conductor having an insulating layer on its surface, the second conductor being laminated to the first conductor, the molten region being a region in which the first conductor and the second conductor, including the insulating layer, are melted, and the molten region has a hole in the center surrounded by the molten region.

It was possible to easily create a conductive area between a conductor with an insulating layer on its surface and another conductor layered on top of it.

1 is an explanatory diagram of the metal ink baking process, (A) a conceptual diagram of the baking process of a baked metal ink conductor by scanning with a baking laser, (B) an enlarged view of the metal ink, and (C) an enlarged view of the baked metal ink. An explanatory diagram of the melting process. (A) A cross-sectional view of a fired metal ink conductor after firing the metal ink. (B) A cross-sectional view of a state in which a melted region has been created using a melting laser. (C) A cross-sectional view of the case in which the depth of the influence of the melting laser is changed by changing the pulse energy of the melting laser and applying it to three locations. When a non-hole-forming welding laser is used for laser irradiation, the range of the heat influence as the irradiation process progresses is shown in Fig. 1. (A) A diagram showing a state in which the molten area does not reach the native oxide layer, and (C) A diagram showing a state in which the molten area has exceeded the native oxide layer. Conductivity test results. 5(A) is a scanning electron microscope photograph of a cross section of the conductive part, and FIG. 6A and 6B are explanatory diagrams of a second embodiment of the present invention. FIG. 11 is a cross-sectional view of a conductive portion according to a third embodiment.

Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same reference numerals in different drawings indicate parts with the same function, and duplicate descriptions in each drawing will be omitted as appropriate. In addition, some of the drawings have been intentionally deformed for the purpose of explanation, and are not drawn to exact scale.

[Distinguishing between before and after baking of metal ink]
Hereinafter, the metal ink before baking will be simply referred to as "metal ink", and the metal ink after baking will be referred to as "baked metal ink" to distinguish them.

[conductor]
The term "conductor" includes wiring and electrodes.

[Meaning of parentheses around terms]
In addition, although it may be expressed as "fired metal ink conductor (second conductor)", the (second conductor) in parentheses indicates the term used in the corresponding claim.

[Meaning of insulating layer]
The insulating layer includes a natural oxide layer (insulating layer) formed by natural oxidation on the surface of a metal conductor (first conductor) whose main material is aluminum or the like.
The insulating layer includes not only natural oxidation but also those formed by artificial processes. For example, a metal conductor (first conductor) coated with an insulating layer made of another material is also included in the present invention.
In the present invention, the insulating layer also includes a layer having a higher electrical resistance than the metal conductor (first conductor), such as a layer having a stain on the surface of the metal conductor (first conductor).

[Electronic components]
In the present invention, any element that is connected to another element by a conductor is included in the "electronic component" of the present invention. For example, the "electronic component" of the present invention also includes a circuit board such as a printed circuit board.

Example 1
Example 1 shown in Figs. 1 to 5 is an example in which a conductive portion 9 is formed between a first conductor A having a natural oxide layer (insulating layer B) 721 on its surface, which is a metal conductor 72, and a second conductor C, which is a fired metal ink conductor 27. Although the materials of the first conductor A and the second conductor C are not limited, an example in which metal ink 2 is used for the second conductor C is used in Example 1. This is to explain how metal ink 2 is used to repair a broken wire or the like. For example, the wiring of a circuit board of a flat panel display may be broken due to dirt or dust that adheres to the board during the manufacturing process. In such a case, the broken wire can be repaired by creating a detour path of metal ink 2 as second conductor C between the first conductor A before and after the broken wire.
Example 1 shows only one example, and the present invention does not exclude the use of a second conductor C made of a material different from the metal ink.

[Insulation layer]
The metal conductor (first conductor A) 72 is mainly composed of a metal such as aluminum or titanium that naturally oxidizes in the atmosphere to form a natural oxide layer (insulating layer B) 721 on the surface.

[Metal ink application process]
1 is an explanatory diagram of the baking process of metal ink 2. Fig. 1(A) is a conceptual diagram of the baking process of a baked metal ink conductor (second conductor C) 27 by scanning with a baking laser 3. A metal conductor (first conductor A) 72 is disposed on a substrate 7. The metal conductor (first conductor A) 72 is a conductor mainly composed of aluminum, and a natural oxide layer (insulating layer B) 721 on the order of several nanometers is formed on its surface. Next, metal ink 2 is applied onto the natural oxide layer (insulating layer B) 721 of the metal conductor (first conductor A).

[Metal ink baking process]
1B is an enlarged view of the metal ink 2. The metal ink 2 is made by forming highly conductive metals such as gold, silver, and copper into nanoparticles and dispersing them in an organic solvent 26. The melting point of metals is dramatically lowered by forming them into nanoparticles. Organic matter 25 is adsorbed on the surfaces of the metal nanoparticles 24, and this organic matter 25 allows the metal nanoparticles 24 to be dispersed in the organic solvent 26 without coagulating with each other.

When the metal ink 2 is heated by irradiation with a baking laser 3 or infrared rays, the organic solvent 26 evaporates, the organic matter 25 on the surface of the metal nanoparticles 24 is desorbed, and the metal nanoparticles 24 aggregate and melt to become metal lumps that become conductive. Any suitable heating means can be used for baking.
A firing laser 3 was used for firing in Example 1. The absorption wavelength of the metal ink 2 varies depending on the type and particle size of the metal, but is around 400 nm for the metal ink 2 containing silver-based metal nanoparticles 24 with a particle size of 20 nm used in Example 1. The firing laser 3 used in Example 1 was a continuous oscillation semiconductor laser having a wavelength around the absorption wavelength.

1C is an enlarged view of the fired metal ink conductor (second conductor C) 27, from which it can be seen that the metal nanoparticles 24 are fused together to form metal lumps. Only the area irradiated with the firing laser 3 is fired to become the fired metal ink conductor (second conductor C) 27, which is conductive.
As shown in FIG. 1A , the firing laser 3 is scanned left and right along the metal ink 2 as indicated by the arrow, firing the metal ink 2 and stacking a fired metal ink conductor (second conductor C) 27 on the underlying metal conductor (first conductor A) 72.

The [metal ink application process] and [metal ink baking process] are combined to form (first process) a process in which a baked metal ink conductor (second conductor C) 27 is laminated onto a metal conductor (first conductor A) 721 having a natural oxidation layer (insulating layer B) 721 on its surface.

Structurally, the laminated structure comprises a metal conductor (first conductor A) 72 and a fired metal ink conductor (second conductor C) 27, the metal conductor (first conductor A) 72 having a natural oxidation layer (insulating layer B) 721 on its surface, and the fired metal ink conductor (second conductor C) 27 being laminated on the natural oxidation layer (insulating layer B) 721 of the metal conductor (first conductor A) 72.

[Melting process]
2A is an explanatory diagram of the melting step. Fig. 2A is a cross-sectional view of a fired metal ink conductor 27 obtained by firing the metal ink 2. Fig. 2A shows the state after firing in the above-mentioned [metal ink firing step].
At this point, the natural oxide layer (insulating layer B) 721 is sandwiched between the metal conductor (first conductor A) 72 and the fired metal ink conductor (second conductor C) 27, so it does not have sufficient conductivity to function as a conductive part 9.

Figure 2 (B) is a cross-sectional view of the state where the melted region 8 has been created by the melting laser 4. The output of the melting laser 4 can vary depending on the thickness of the metal conductor (first conductor A) 72 and the fired metal ink conductor (second conductor C) 27, the type of metal, etc. It is undesirable for the influence of the melting laser 4 to extend to the substrate 7, and it is preferable for the output to have an effect at least on the natural oxide layer (insulating layer B) 721. More preferably, the output is such that it extends beyond the natural oxide layer (insulating layer B) 721 and reaches the metal conductor (first conductor A) 72.

The melting laser 4 destroys the natural oxide layer (insulating layer B) 721, creating a melted region 8 that is a mixture of silver from the fired metal ink conductor (second conductor C) 27, aluminum from the metal conductor (first conductor A) 72, and aluminum oxide from the natural oxide layer (insulating layer B) 721.

In the center where the melting laser 4 hits, a hole 74 is created as a trace of evaporated metal, as shown in the figure. The molten area 8, shown by hatching, is formed on the inner wall of the hole 74. The molten area 8 contains a large amount of highly conductive aluminum and silver, and is only mixed with a natural oxide layer (insulating layer B) 721 of at most a few nanometers, making it an area with significantly high conductivity. As a result, the irradiation of the melting laser 4 (second process) melts the metal conductor (first conductor A) 72 and the baked metal ink conductor (second conductor C) 27, including the natural oxide layer (insulating layer B) 721, to create a molten area, and a hole 74 surrounded by the molten area 8 is formed in the center of the molten area 8.

As described above, a molten region 8 is formed in which the natural oxide layer (insulating layer B) 721, the fired metal ink conductor (second conductor C) 27, and the metal conductor (first conductor A) 72 are melted, and a hole 74 is formed in the center of the molten region 8, surrounded by the molten region 8.

[Another embodiment of the melting step]
Fig. 2(C) is a cross-sectional view showing a case where the melting laser 4 is applied to three locations with different pulse energies, thereby changing the depth of the influence of the melting laser 4. (Note that Fig. 2 is a conceptual diagram, and low, medium, and high powers are a comparison of the pulse energies in this diagram.)

In FIG. 2(C)(a), a melting laser 4 with low output pulse energy is irradiated. The melted area 8 remains within the range of the fired metal ink conductor (second conductor C) 27, and no improvement in conductivity between the metal conductor (first conductor A) 72 and the fired metal ink conductor (second conductor C) 27 can be expected.

In addition, in FIG. 2(C)(b), a melting laser 4 with medium output pulse energy is irradiated. The effect of the melting laser 4 extends to the vicinity of the natural oxide layer (insulating layer B) 721, and although it is expected that the conductivity between the metal conductor (first conductor A) 72 and the fired metal ink conductor (second conductor C) 27 will improve, the thickness of the fired metal ink conductor (second conductor C) 27 is not uniform, so the conductivity may not improve as much as expected.

In FIG. 2(C)(c), a melting laser 4 with high output pulse energy is irradiated. The melted region 8 is formed beyond the natural oxide layer (insulating layer B) 721 of the metal conductor (first conductor A) 72, which reliably improves the conductivity between the metal conductor (first conductor A) 72 and the fired metal ink conductor (second conductor C) 27.

The metal ink 2 is applied to each location where the conductive portion 9 is to be formed, and the application conditions for each location are not exactly the same, so the conditions (thickness, etc.) of the fired metal ink conductor (second conductor C) 27 are not constant. Therefore, by irradiating the melting laser 4 to two or more locations, preferably three locations, with different pulse energies, it is possible to reliably ensure conductivity without having to conduct experiments to determine the output suitable for the conditions for each location where the conductive portion is to be formed. The pulse width and number of irradiations may also be changed.

In summary, in FIG. 2(c), the melting laser 4 is applied to three locations with different pulse energies, but two or more locations are sufficient. To create melted regions 8 with different depths in two or more locations, a third process can be added following the second process to create another melted region with a different depth in a different location from the melted region formed in the second process.

In addition, two or more molten regions are provided, and the depths of the molten regions are different, ensuring electrical conductivity.

In the embodiment, a melting laser 4 is used that is set to form a hole 74 by pulse energy. The hole 74 is formed in the center of the melting region 8, surrounded by the melting region 8, so that the depth of the melting region 8 can be known. In addition, the formation of the hole 74 allows heat to be released through the hole 74, allowing the melting region 8 to be cooled quickly. In general, thermal energy affects members near the melting region 8, and when a laser is applied to a substrate 7 in which an organic layer or the like is close to the melting region 8, the organic layer may be altered. However, the melting laser 4 of the present invention is set to form a hole 74 by irradiating a nanosecond pulse laser at high power to form a minute hole 74 that penetrates the natural oxide layer (insulating layer B) 721. The heat of the melting region 8 is also released from the hole 74, accelerating the cooling speed, and the effect of the heat can be limited to only a very small area around the melting region 8.

On the other hand, if a welding laser 41 that does not form a hole 74 is used, the melted area 8 becomes larger and the area affected by heat also becomes larger.

Figure 3, which corresponds to a comparative experiment, is an explanatory diagram of the range of the thermal effect as the irradiation process progresses when laser irradiation is performed using a welding laser 41 that does not form a hole 74. Figure 3(A) is a diagram of the state immediately after irradiation, Figure 3(B) is a diagram of the state where the molten area 8 has not reached the natural oxide layer (insulating layer B) 721, and Figure 3(C) is a diagram of the state where the molten area 8 has exceeded the natural oxide layer (insulating layer B) 721.

As shown in FIG. 3(A), the melted area 8 immediately after irradiation is small, but heat is diffused by thermal conduction from the irradiation area of the welding laser 41 that does not form the hole 74. As irradiation continues, the melted area 8 gradually expands as shown in FIG. 3(B). As irradiation continues further, heat conduction continues, and the melted area 8 gradually expands, and a melted area 8 larger than the irradiation area of the welding laser 41 that does not form the hole 74 is formed as shown in FIG. 3(C), melting the natural oxide layer (insulating layer B) 721. The temperature of the melted area 8 reaches the melting point of the metal and is very high, and the area around the melted area 8 becomes an area 412 affected by heat due to thermal conduction. At this time, heat is dissipated only from the surface of the baked metal ink conductor (second conductor C) 27, and the larger the volume of the melted area 8, the less the heat dissipation proportional to the surface area can keep up. The area 412 affected by heat expands due to the high-temperature metal accumulated in the melted area 8, which has increased in volume.

In the first embodiment, since the hole 74 is provided in the center of the molten region 8 as shown in FIG. 2, the metal in the molten region 8 cools quickly.
In this manner, when the melting laser 4 that forms the hole 74 is used, the area 412 affected by heat can be made significantly smaller than when the welding laser 41 that does not form the hole 74 is used.

Experimental examples of the present invention will now be described.
(Experiment 1: Experiment showing the relationship between electrical resistance and pulse energy)
Experiment 1 is an experiment to investigate how the electrical resistance changes before and after the destruction of the natural oxide layer (insulating layer B) 721 by changing the depth of the melted region 8. In experiment 1, a sample for irradiation with the welding laser 4 was prepared by applying metal ink 2 onto a metal conductor 72 on a substrate 7 and baking it to form a baked metal ink conductor 27. The melting laser 4 was then irradiated onto the sample under different conditions. In order to change the depth of the melted region 8 formed by the melting laser 4, the pulse energy of the melting laser 4 was changed among four conditions: 100, 200, 250, and 300 μJ. Moreover, the conditions other than the pulse energy were the same.

The conditions of Experiment 1 will now be described.
(1) Melting laser 4
Wavelength 532 nm
Pulse width: 10ns
Number of pulses: 1 Melting processing setting size: 1 μm x 1 μm
Experiments were conducted with pulse energies of 100, 200, 250, and 300 μJ (see Figure 4).
(2) Metal conductor (first conductor A) 72
Metal type: Aluminum Wiring width: 5 μm
(3) Baked metal ink conductor (second conductor C) 27
Metal type: Silver (nanoparticles)
Wiring thickness: 0.4 μm
Under the above experimental conditions, samples were created by varying the pulse energy of the melting laser 4, and the electrical resistance between the metal conductor (first conductor A) 72 and the fired metal ink conductor (second conductor C) 27 was measured. The results are shown in FIG.

At a pulse energy of 100 μJ, the electrical resistance was 340 Ω on average, and there was no improvement in conductivity compared to before irradiation with the melting laser 4. It is presumed that the effect of the melting laser 4 is limited to the area of the fired metal ink conductor (second conductor C) 27, as shown in FIG. 2(C)(a).

At a pulse energy of 200 μJ, the electrical resistance was 50 Ω on average, and a significant improvement in conductivity was observed. It is presumed that the effect of the melting laser 4 remains near the natural oxide layer (insulating layer B) 721, as shown in FIG. 2(C)(b).

At pulse energies of 250 μJ and 300 μJ, the average electrical resistance drops sharply to nearly 0 Ω. It is assumed that the natural oxide layer (insulating layer B) 721 is melted, and that the influence of the melting laser 4 extends to the metal conductor (first conductor A) 72 as shown in Figure 2 (C) (c). At a pulse energy of 200 μJ, the error bars (3σ) remained at about 30 Ω on one side and 60 Ω on both sides, and there was a large variation in the observed electrical resistance, but at pulse energies of 250 μJ and 300 μJ, the error bars (3σ) were 2 to 3 Ω.

This shows that the influence of the melting laser 4 reaches a point where electrical conductivity can be reliably ensured. It also shows that the electrical resistance is sufficiently small, and that the conductive portion 9 is formed stably with little variation.

(Experiment 2: Confirmation of the melted region)
In order to confirm the presence of the molten region 8, experiment 2 was carried out in which the conductive portion 9 was photographed using a scanning electron microscope.
5A and 5B are scanning electron microscope photographs of the conductive portion 9, and FIG. 5A is a scanning electron microscope photograph of the conductive portion 9, and FIG. 5B is an explanatory diagram of the scanning electron microscope photograph of FIG. 5A.

The photographed samples were prepared and photographed as follows.
(1) The substrate 7 having the conductive portion 9 produced as described above was used as a sample, and was covered with a protective film 73 as a pretreatment for the subsequent electron beam cutting.
(2) The substrate 7 was cut with an electron beam to obtain a cross section.
(3) The sample prepared as described above was photographed with a scanning electron microscope from an angle that allowed the cross section to be seen.

The hatched protective film 73 in FIG. 5B is a coating applied during preparation of the sample, and is not present on the original conductive portion 9 .
There is a natural oxide layer (insulating layer B) 721 on the surface of the metal conductor (first conductor A) 72, but it is only a few nanometers thick and is not visible at this magnification.

A hole 74 is formed in the area irradiated with the melting laser 4. On the side of the hole 74, the boundary between the fired metal ink conductor (second conductor C) 27 and the metal conductor (first conductor A) 72, which should originally exist, is blurred or has completely disappeared. This shows that the metal conductor (first conductor A) 72 and the fired metal ink conductor (second conductor C) 27, including the natural oxidation layer (insulating layer B) 721, have melted to form the molten area 8.

(Summary of Experiments 1 and 2)
From the above experiments, it was confirmed that the metal conductor (first conductor A) 72 and the baked metal ink conductor (second conductor C) 27, including the natural oxide layer (insulating layer B) 721, were melted by irradiation with the melting laser 4 to form a melted region 8. It was also confirmed that the electrical resistance between the metal conductor (first conductor A) 72 and the baked metal ink conductor (second conductor C) 27 was significantly reduced by irradiation with the melting laser 4, resulting in a result with little variation in the electrical resistance value. Since the electrical resistance value has little variation, it can be said that the present invention can be put to practical use.

Example 2
Example 2 is an application example of the present invention. Figure 6 is an explanatory diagram of Example 2, in which Figure 6(A) is a plan view of a substrate 7 of a TFT liquid crystal panel, and Figure 6(B) is an enlarged view of a bypass circuit provided in Figure 6(A).

Field-effect transistors 12 are mounted on the substrate 7 of the TFT liquid crystal panel of an LCD (liquid crystal display), and metal conductors (first conductor A) 72 made mainly of aluminum are wired. One of the wires has a defect (disconnection) 722, and would normally be discarded as a defective product.

A board 7 with a defect (disconnection) 722 is repaired with a detour 76 made of a fired metal ink conductor (second conductor C) 27, thereby improving product yield.

There are various possible causes for the defect (disconnection) 722, but the main cause is the adhesion of dirt. It is possible to connect the defect (disconnection) 722 directly in a straight line over the shortest distance, but since there is a possibility that dirt or other debris may remain, a detour route 76 is used instead. Of course, the defect (disconnection) 722 may also be repaired by connecting it directly in a straight line over the shortest distance.

The detour path 76 using the silver metal ink 2 is sintered by a sintering laser 3 (not shown) to become a sintered metal ink conductor (second conductor C) 27.
As a result, in the conductive portion 9, the substrate 7, the metal conductor (first conductor A) 72, the natural oxidation layer (insulating layer B) 721, and the fired metal ink conductor (second conductor C) 27 are stacked in this order from the bottom up.

The melting laser 4 is irradiated to each conductive part 9 at three locations, each with a different pulse energy intensity. (See Figure 2 (C))

The conductive portion 9 is formed in the melted region 8 formed around the three holes 74. If any one of the three melted regions 8 with different pulse energy intensities reaches the natural oxide layer (insulating layer B) 721, the electrical resistance between the metal conductor (first conductor A) 72 and the fired metal ink conductor (second conductor C) 27 is reduced to a level that does not affect the operation of the TFT liquid crystal panel.
In addition, since a hole 74 surrounded by the molten region 8 is formed in the center of the molten region 8, the molten metal in the molten region 8 is cooled quickly by releasing heat from the hole 74, thereby reducing the thermal impact on the surrounding area of the molten region 8.

The present invention can be used in a manufacturing method for a substrate (electronic component) of a TFT liquid crystal panel as in the second embodiment.
Furthermore, the present invention can provide a substrate (electronic component) for a TFT liquid crystal panel having a conductive portion 9 provided with a molten region 8 in which the metal conductor (first conductor A) 72 and the fired metal ink conductor (second conductor C) 27, including the natural oxidation layer (insulating layer B) 721, are melted.

Furthermore, the substrate (electronic component) of the TFT liquid crystal panel provided as described above can be assembled with other components to form a manufacturing method for a product called a TFT liquid crystal panel.
Furthermore, the TFT liquid crystal panel (electronic component) provided as described above can be assembled with other components to provide a product called a liquid crystal display.
The details of TFT liquid crystal panels and liquid crystal display technology and manufacturing methods are widely known and will not be described here.

Example 3
FIG. 7 is a cross-sectional view of a conductive portion 9 according to the third embodiment.
In the first and second embodiments, the natural oxide layer 721 is used as the insulating layer B. In the third embodiment, the insulating layer B is artificially formed on the surface of the metal conductor (first conductor A). The second conductor C does not have to be a fired metal ink conductor. Furthermore, the first conductor A and the second conductor C may be made of the same metal material.

As one example, we will show an example of a laminated circuit board 5. In the laminated circuit board 5, multiple conductors are stacked with an insulating layer B sandwiched between them, such as a first conductor A, an insulating layer B, a second conductor C, an insulating layer B, a first conductor A, an insulating layer B, and a second conductor C.

By irradiating the laminated conductors with a melting laser 4, a conductive portion 9 is formed in the melted region 8 that melts the first conductor A, the second conductor C, and the insulating layer B. The melted region 8 becomes the conductive portion 9, and all of the laminated conductors can be made conductive.

Although the first to third embodiments of the present invention have been described above in detail with reference to the drawings, the specific configurations are not limited to these embodiments, and the present invention also includes design changes and the like within the scope of the present invention that do not deviate from the gist of the present invention.
Furthermore, the above-described embodiments can be combined by utilizing each other's techniques, so long as there are no particular contradictions or problems in the objects, configurations, and the like.

A: First conductor B: Insulating layer C: Second conductor 2: Metal ink 24: Metal nanoparticles 25: Organic substance 26: Organic solvent 27: Sintered metal ink conductor (second conductor)
3 Firing laser 4 Melting laser 41 Welding laser 412 Area affected by heat 5 Multilayer circuit board 7 Board 72 Metal conductor (first conductor)
721 Natural oxide layer (insulating layer)
722 Defect (disconnection)
73 Protective film 74 Hole 75 Field effect transistor 76 Detour circuit 8 Melted region 9 Conductive portion

Claims (8)

A first step of laminating a second conductor on a first conductor having an insulating layer on a surface thereof;
a second step of melting the first conductor and the second conductor including the insulating layer to create a molten region and forming a hole in the center of the molten region surrounded by the molten region ;
Following the second step,
A method for manufacturing a conductive part, comprising a third step of forming another molten region at a position different from the molten region formed in the second step, the molten region having a different depth from the molten region formed in the second step . A first step of laminating a second conductor on a first conductor having an insulating layer on a surface thereof;
a second step of melting the first conductor and the second conductor including the insulating layer to create a molten region and forming a hole in the center of the molten region surrounded by the molten region ;
the insulating layer is a native oxide layer formed by oxidizing a metal of the first conductor;
The method for manufacturing a conductive part , wherein the second conductor is a sintered metal ink conductor formed by sintering a metal ink . 3. A method for manufacturing an electronic component, comprising the steps of: forming the conductive portion according to claim 1 on a substrate; and forming the conductive portion on the substrate. A method for manufacturing a product, comprising assembling the electronic component of claim 3 with other electronic components to produce the product. a first conductor, a second conductor, and a fusion region;
the first conductor has an insulating layer on a surface thereof;
the second conductor is laminated on the first conductor;
the molten region is a region in which the first conductor and the second conductor, including the insulating layer, are melted, and the molten region has a hole at its center that is surrounded by the molten region;
The conductive portion is characterized in that the melted regions are provided in two or more places, and the melted regions have different depths . a first conductor, a second conductor, and a fusion region;
the first conductor has an insulating layer on a surface thereof;
the second conductor is laminated on the first conductor;
the molten region is a region in which the first conductor and the second conductor, including the insulating layer, are melted, and the molten region has a hole at its center that is surrounded by the molten region;
the insulating layer is a native oxide layer derived from a metal of the first conductor,
The conductive portion, wherein the second conductor is a fired metal ink conductor formed by firing a metal ink . The first conductor is disposed on a substrate, and the electronic component has the conductive portion according to claim 5 or 6 . A product incorporating the electronic component according to claim 7.

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