JP6301632B2 - Connection structure and copper particle-containing paste for forming the connection structure - Google Patents

Description

  The present invention relates to a connection structure, and more particularly, to a connection structure that realizes electrical connection of conductors formed on a substrate, and a copper particle-containing paste for forming the connection structure.

  Conventionally, a conductive portion is formed by paste printing in a manufacturing process of an electric circuit board. As the paste material, Ag paste has been used so far, but the ion migration of Ag becomes a problem in fine wiring, thin layered substrates, etc., and examination of Cu paste is now underway. At this time, the adhesiveness of the paste to the organic substrate or inorganic substrate serving as the base material is an important characteristic. Further, in the interlayer connection, the connection between the via connection or through-hole connection and the electrode, and in the intra-layer connection, the bondability between the paste and the electrode is an important characteristic in the electrode-electrode connection. Therefore, in order to improve the adhesion to an organic substrate or an inorganic substrate, an organic binder is usually added to the paste. At this time, although the adhesion to the substrate was improved, good conductivity could not be obtained due to the remaining organic binder.

  In order to solve such problems, there has been proposed a method for printing on an organic substrate or an inorganic substrate using a paste that does not contain an organic binder or has a small amount of organic binder added (Patent Document). 1).

JP 2012-18783 A

  However, in the above conventional method, the conductivity is improved by sacrificing the adhesiveness of the paste to the substrate by reducing the addition amount of the organic binder and the curing agent. Since the conductivity is in a trade-off relationship, the improvement effect is limited. Further, in applications where the contact portion with the paste is formed on both the substrate and the conductor in order to connect the electrodes, the connectivity to the conductor is also important. Therefore, there is a need for a technique that can simultaneously improve the substrate adhesion and the adhesion and conductivity of the conductor connecting portion without using an organic binder.

  It is an object of the present invention to improve both the adhesion to a substrate and the adhesion to a conductor while maintaining good electrical connectivity between layers and electrodes, and to realize a highly reliable connection. It is an object of the present invention to provide a connection structure that can be used, and a copper particle-containing paste for forming the connection structure.

  To achieve the above object, a connection structure of the present invention comprises a plurality of copper conductors forming at least a part of a circuit on a substrate, and a copper sintered body connecting the plurality of conductors, The copper sintered body has a substrate contact portion that contacts the substrate and a conductor contact portion that contacts the copper conductor, and the oxygen concentration in the copper sintered body is determined by the EDX method (energy dispersive X-ray). The average atomic number concentration measured by the analysis method is less than 10%, and the oxygen concentration of the substrate contact portion is higher than the oxygen concentration of the conductor contact portion.

  The oxygen concentration of the substrate contact portion is more than 6% and 10% or less in terms of the number of atoms measured by the EDX method, and the oxygen concentration of the conductor contact portion is the number of atoms measured by the EDX method. The concentration is 1% or more and 6% or less.

  Preferably, the plurality of copper conductors and the copper sintered body are formed on the substrate, and a part of the copper sintered body covers at least a part of the plurality of copper conductors and a part of the substrate. The substrate contact portion is disposed on the substrate, and the conductor contact portion is disposed on the copper conductor.

  Preferably, the copper sintered body is formed so as to be embedded in a through hole provided so as to penetrate in the thickness direction of the substrate, and the copper conductor is formed in the copper hole formed in the through hole. It arrange | positions covering the both end surfaces of a bonded body, the said board | substrate contact part is arrange | positioned in contact with the internal peripheral surface of the said through-hole, and the said conductor contact part is arrange | positioned in contact with the said copper conductor.

  Moreover, it is preferable that the thickness of the substrate contact portion is 10 μm or less.

To achieve the above object, the copper particle-containing paste of the present invention is a copper particle paste for forming a copper sintered body that connects between a plurality of copper conductors and forms at least a part of a circuit on a substrate. In the X-ray diffraction measurement, when the peak height of the Cu diffraction spectrum is H1, and the peak height of the Cu ₂ O diffraction spectrum is H2, the X-ray diffraction peak intensity ratio (H2 / [H1 + H2]) is 0. 8 or more It is characterized by containing copper particles whose surface layer is made of copper oxide, which is 86 or less, and a polyol having two or more hydroxyl groups in the molecule as a solvent.

  Also preferably, the polyol is ethylene glycol, diethylene glycol, glycerin, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-butene-1,4-diol, pentanediol, hexanediol, octanediol, 1,1,1-trishydroxymethylethane, 2-ethyl-2-hydroxymethyl-1,3-propanediol, 1,2, Selected from the group consisting of 6-hexanetriol, 1,2,3-hexanetriol, 1,2,4-butanetriol, threitol, erythritol, pentaerythritol, xylitol, sorbitol, pentitol, terpineol and hexitol 1 type, or 2 or more types.

  According to the present invention, the oxygen concentration in the copper sintered body is less than 10% in terms of the average atomic number concentration measured by the EDX method. The copper sintered body has a substrate contact portion that contacts the substrate and a conductor contact portion that contacts the copper conductor, and the oxygen concentration of the substrate contact portion is higher than the oxygen concentration of the conductor contact portion. As a result, the adhesiveness at the interface between the copper sintered body and the substrate and the adhesiveness at the interface between the copper sintered body and the conductor are obtained without impairing the electrical connectivity at the interface between the copper sintered body and the copper conductor. Can be improved. Therefore, a highly reliable connection can be realized between the layers or the electrodes.

It is a figure which shows schematically the connection structure which concerns on embodiment of this invention, (a) is a top view, (b) is sectional drawing which follows line AA. It is a partial expanded sectional view of FIG.1 (b). It is sectional drawing which shows the modification of the connection structure of FIG. It is a figure which shows the relationship between the oxidation degree of the copper fine particle contained in the paste for forming the connection structure of FIG. 1, and the oxidation density | concentration of a copper sintered compact.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  1A and 1B are plan views schematically showing a configuration of a connection structure according to the present embodiment, in which FIG. 1A is a plan view and FIG. 1B is a cross-sectional view taken along line AA. FIG. 2 is a partially enlarged sectional view of FIG.

  As shown in FIG. 1 (a), the connection structure is composed of two copper conductors 2 and 2 that form part of a circuit on a substrate 1 and sintered copper that connects the two copper conductors 2 and 2 together. And a body 3.

  The substrate 1 is an organic substrate such as an epoxy resin or a polyimide resin, or an inorganic substrate such as glass (for example, borosilicate glass, aluminoborosilicate glass, or aluminosilicate glass).

  The two copper conductors 2 and 2 are conductor patterns formed on the main surface 1a of the substrate by a screen printing method or the like, and are formed at a predetermined distance. The thickness of the copper conductor 2 is, for example, 100 μm or less. In the case of an organic substrate such as an epoxy substrate, a copper conductor having a thickness of about 10 μm, or in the case of an inorganic substrate such as a glass substrate, a copper having a thickness of about 1.0 μm. A conductor is selected. The copper conductor 2 is a conductor containing copper or a copper alloy.

(Copper sintered body)
The copper sintered body 3 is a conductor containing a substantially long copper or copper alloy that electrically connects the two copper conductors 2, 2, and after applying a copper fine particle-containing paste described later to a predetermined position, heating It is formed by firing. The thickness of the copper sintered body 3 is determined according to the thickness of the copper conductor 2 and is formed mainly from the viewpoint of electrical resistance so as to be equal to or greater than the thickness of the copper conductor 2, preferably It is formed so that the thickness is about twice. Alternatively, when there is a thickness limitation in product design, it is formed to be as large as possible within the limitation range.

  Specifically, as shown in FIGS. 1B and 2, the copper sintered body 3 includes a substrate contact portion 31 that contacts the substrate 1 and a conductor contact that contacts the two copper conductors 2 and 2. Parts 32 and 32. In this embodiment, the substrate contact portion 31 is disposed on the main surface 1 a of the substrate 1, and the conductor contact portion 32 is disposed on the upper surface 2 a and the side surface 2 b of the copper conductor 2. The substrate contact portion 31 is configured by a high oxygen concentration layer including a contact surface 31 a with the substrate 1, and the conductor contact portion 32 is configured by a low oxygen concentration layer including a contact surface 32 a with the copper conductor 2. Has been. A part of the conductor abutting portion 32 abuts on the main surface 1 a of the substrate 1, but the portion is arranged in abutment with the side surface 2 b of the copper conductor 2, so that the conductor abutting portion 32 is composed of a low oxygen concentration layer. Yes.

  The oxygen concentration of the entire copper sintered body 3 is less than 10% in terms of the average atomic number concentration measured by the EDX method, preferably 5% or more and less than 9%, more preferably 7% or more and less than 8%. If the oxygen concentration of the entire copper sintered body is too high, the electrical resistance increases and the electrical connectivity is poor.

  The oxygen concentration of the substrate contact portion 31, that is, the high oxygen concentration layer, is more than 6% and not more than 10%, more preferably not less than 8% and not more than 9% in terms of atomic number concentration (mol%) measured by the EDX method. By setting the oxygen concentration of the substrate contact portion 31 to more than 6.0% and not more than 10%, C atoms on the resin substrate surface and O atoms on the substrate contact portion are combined, or Si atoms on the glass substrate surface are combined. It is presumed that the O atom in the substrate contact portion is bonded to improve the adhesion with the substrate 1. Further, since the substrate contact portion 31 is formed at a position away from the conductive path, the electrical connectivity is not affected even if the oxygen concentration is relatively high. If the oxygen concentration of the substrate contact portion 31 is less than 6.0%, the adhesion to the substrate 1 is poor, and if it exceeds 10%, the electrical resistance is affected and the electrical connectivity is poor.

  The oxygen concentration of the conductor contact portion 32, that is, the low oxygen concentration layer is 1% or more and 6% or less, preferably 3% or more and 6% or less, more preferably 3% or more and 3% or less in terms of the number of atoms measured by the EDX method. 5% or less. By setting the oxygen concentration of the conductor contact portion 32 to 1% or more and 6% or less, the Cu atoms of the conductor contact portion 32 and the Cu atoms of the copper conductor 2 are bonded to improve the adhesion. The conductor contact portion 32 is formed on the conductive path, but can maintain sufficient electrical connectivity because the ratio of copper oxide atoms to copper atoms is low. When the oxygen concentration of the conductor abutting portion 32 is less than 1%, the adhesion to the copper conductor 2 is poor, and when it exceeds 6%, the electric resistance is obtained and the electrical connectivity is poor.

  The thickness of the substrate contact portion 31 is preferably more than 0 μm and 10 μm or less. Since the substrate contact portion 31 has a high oxygen concentration, if the thickness exceeds 10 μm, the conductivity of the entire copper sintered body 3 is lowered. The thickness direction of the substrate contact portion 31 is the same as the thickness direction of the substrate 1. Also, the thickness of the conductor contact portion 32 is preferably more than 0 μm and 10 μm or less.

(Copper fine particle containing paste)
The copper fine particle-containing paste is a conductor-forming composite material comprising 10 to 90% by weight of copper fine particles and the balance (90 to 10% by mass) of an organic dispersion medium. When the copper concentration is lower than 10% by weight, it becomes difficult to form a thick sintered body and the electrical connectivity is poor. If the copper concentration is higher than 90% by weight, it becomes difficult to apply the paste to the metal substrate or the copper conductor. The average particle diameter of copper fine particles contained in the paste (average particle diameter of primary particles) is 10 nm to 300 nm. In this embodiment, the organic dispersion medium is made of polyol, but is not limited thereto, and may contain polyol and other materials such as additives. The copper fine particles may be a copper alloy.

  Here, the average particle diameter of the primary particles means the diameter of the primary particles of the individual copper fine particles constituting the secondary particles. The diameter of the primary particles can be measured using an electron microscope. Moreover, an average particle diameter means the number average particle diameter of a primary particle.

In the present embodiment, the oxidation degree of the copper fine particles is defined as follows. That is, in X-ray diffraction measurement (XRD), when the peak height of the diffraction spectrum on the Cu (111) plane is H1, and the peak height of the diffraction spectrum on the Cu ₂ O (111) plane is H2, the X-ray diffraction peak The intensity ratio (H2 / [H1 + H2]) is 0.67 or more and 0.91 or less, preferably 0.8 or more and 0.86 or less. If the X-ray diffraction peak intensity ratio is less than 0.67, good adhesion cannot be obtained, and if it exceeds 0.91, the electrical connectivity is inferior.

  The organic dispersion medium is composed of at least one polyol, for example, ethylene glycol, diethylene glycol, glycerin, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, , 4-butanediol, 2-butene-1,4-diol, pentanediol, hexanediol, octanediol, 1,1,1-trishydroxymethylethane, 2-ethyl-2-hydroxymethyl-1,3-propane Diol, 1,2,6-hexanetriol, 1,2,3-hexanetriol, 1,2,4-butanetriol, threitol, erythritol, pentaerythritol, xylitol, sorbitol, pentitol, terpineol and One selected from the group consisting of hexitols Is two or more kinds of material.

  Since polyol has reducibility, the surface of copper fine particles is reduced, and when heat treatment is performed, the polyol evaporates continuously and is reduced and calcined in an atmosphere where the liquid and vapor are present. Sintering is promoted.

(Method for forming copper sintered body)
As a method of providing the oxygen concentration distribution as described above in the copper sintered body 3, for example, a copper fine particle having a predetermined degree of oxidation and a paste composed of a solvent having a reducing property during heating and firing are used. The method of heating and baking after apply | coating to the copper surface and a substrate surface is mentioned. The heating / firing method may be divided into a plurality of different atmospheres, and the heat source used for heating may be, for example, a heater or light, but is not limited thereto. In the obtained sintered body, the reduction effect of copper fine particles due to the catalytic action of copper is large in the vicinity of the copper conductor, but the catalytic effect of copper does not work in the vicinity of the resin interface, so the reduction effect of the copper fine particles is small. Thereby, a low oxygen concentration layer is formed in the conductor contact portion that contacts the copper conductor, and a high oxygen concentration layer is formed in the substrate contact portion that contacts the substrate.

  As described above, according to this embodiment, the oxygen concentration in the copper sintered body 3 is less than 10% in terms of the average atomic number concentration measured by the EDX method. The copper sintered body 3 includes a substrate contact portion 31 that contacts the substrate 1 and conductor contact portions 32 and 32 that contact the two copper conductors 2 and 2, and oxygen in the substrate contact portion 31. The concentration is higher than the oxygen concentration of the conductor contact portion 32. Thereby, the adhesiveness in the interface of the copper sintered compact 3 and the board | substrate 1 can be improved, without impairing the electrical connectivity in the interface of the copper sintered compact 3 and the copper conductor 2. FIG. Therefore, a highly reliable connection can be realized between the copper conductors 2 and 2 formed on the main surface 1a of the substrate 1.

  Although the connection structure according to the present embodiment has been described above, the present invention is not limited to the described embodiment, and various modifications and changes can be made based on the technical idea of the present invention.

  For example, FIG. 1 shows a form in which the copper sintered body is formed on the substrate. However, the present invention is not limited to this, and the copper sintered body may be formed in a through hole provided in the substrate.

  Specifically, as shown in FIG. 3, the connection structure includes two copper conductors 6, 6 formed on both main surfaces 5 a, 5 a of the substrate 5, and copper that connects the copper conductors 6, 6. And a sintered body 7. The copper sintered body 7 is formed by being embedded in a through hole provided so as to penetrate the substrate 5 in the thickness direction, and the copper conductor 6 is formed of the copper sintered body 7 formed in the through hole. It arrange | positions in contact with both end surfaces.

  The copper sintered body 7 has a substrate contact portion 72 that contacts the inner peripheral surface 5 b of the substrate 5 and a conductor contact portion 71 that contacts the inner surface 6 a of the copper conductor 6. The substrate contact portion 72 is configured by a high oxygen concentration layer including a contact surface 72 a with the substrate 5, and the conductor contact portion 71 is configured by a low oxygen concentration layer including a contact surface 71 a with the copper conductor 6. ing. The oxygen concentration in the copper sintered body 7 is less than 10% in terms of the average atomic number concentration measured by the EDX method, and the oxygen concentration of the substrate contact portion 72 is higher than the oxygen concentration of the conductor contact portion 71. A part of the conductor abutting portion 71 abuts on the inner peripheral surface 5 b of the substrate 5, but the portion is arranged in abutting contact with the inner side surface 6 a of the copper conductor 6, so that it is configured with a low oxygen concentration layer. Has been.

  The thickness of the substrate contact portion 72 is preferably more than 0 μm and not more than 10 μm. Since the substrate contact portion 71 has a high oxygen concentration, if the thickness exceeds 10 μm, the conductivity of the entire copper sintered body 7 is lowered. The thickness direction of the substrate contact portion 72 is the same as the radial direction of the through hole. Also, the thickness of the conductor contact portion 71 is preferably more than 0 μm and 10 μm or less. The thickness direction of the substrate contact portion 72 is the same as the thickness direction of the copper conductor 6.

  According to this modification, the adhesion at the interface between the copper sintered body 7 and the substrate 5 can be improved without impairing the electrical connectivity at the interface between the copper sintered body 7 and the copper conductor 6. A highly reliable connection can be realized between the copper conductors 6 and 6 formed on both the main surfaces 5a and 5a of the substrate 5.

  In FIG. 3, the copper sintered body is formed in the single-layer through hole. However, the present invention is not limited to this, and the copper sintered body may be formed in a via provided in the multilayer substrate. Thereby, a highly reliable interlayer connection can be realized even in a multilayer substrate.

  Hereinafter, preferred embodiments of the present invention will be specifically described based on Examples and Comparative Examples, but the present invention is not limited to these Examples.

[Examples 1 to 4]
(Copper nano paste)
First, copper fine particles that had been oxidized so as to have a predetermined oxidation degree were mixed with glycerin to prepare a copper nano paste (copper particle-containing paste) having a copper concentration of 50 wt% and a glycerin concentration of 50 wt%.

(Circuit board)
Two copper electrodes having a thickness of 100 μm □ and a thickness of 20 μm were arranged on the epoxy resin substrate at an interval of 400 μm on the same surface.

(Connection procedure)
Copper nano paste was applied between two copper electrodes using a metal mask having a thickness of 100 μm, and then left to stand on a hot plate heated to 140 ° C. for 90 seconds and dried. In the immediate vicinity of the coated copper nano paste, a nozzle for blowing nitrogen (gas) is brought close to a distance of about 10 mm from the substrate, nitrogen is supplied, and the copper nano-powder is irradiated with laser light with the oxygen partial pressure lowered. The paste was baked. The laser driving conditions were a wavelength of 980 nm, an output of 1.0 W, an irradiation time of 70 ms, and a beam spot diameter of 800 μm.

(Measuring method)
(A) Copper fine particle oxidation degree In copper nanopaste, the intensity ratio (H2 / (H1 + H2)) of Cu peak height H1 and Cu ₂ O peak height H2 in the XRD method spectrum was measured.

(B) Copper sintered body oxygen concentration (atomic number concentration)
After firing the copper nanopaste, the copper sintered layer was cut to prepare a cross-section sample, and the cross section corresponding to the following position was weighed with an EDX analyzer attached to an SEM (electron microscope) to obtain an oxygen concentration. At this time, the acceleration voltage of electron beam irradiation was 20 kV.
Copper sintered body average: Arbitrary three places (average value) excluding substrate vicinity and electrode vicinity
In the vicinity of the substrate: a position 5 μm away from the interface between the copper sintered body and the substrate in the thickness direction. In the vicinity of the electrode: a position 5 μm away from the interface between the copper sintered body and the substrate in the thickness direction. FIG. 4 shows the relationship between the degree of oxygen and the copper sintered body oxygen concentration.

(Evaluation method)
(A) Resistance between conductors After sintering the copper nanopaste, the electrical resistance between the electrodes was measured, and a resistance value of 1.0Ω or less was accepted.
(B) Substrate adhesion and conductor adhesion The adhesion of the copper sintered layer was evaluated by a pencil scratch test. The adhesion between the substrate and the conductor was individually observed, and the case where both of them had a hardness of 5H or less and no peeling occurred was regarded as acceptable.

[Examples 5 to 8]
It measured and evaluated by the method similar to Examples 1-4 except having used the borosilicate glass substrate instead of the epoxy resin board | substrate of Examples 1-4.

[Examples 9 and 10]
It measured and evaluated by the method similar to Example 1 except having replaced with the glycerol of Example 1 and having used ethylene glycol or 1, 2- propanediol as a solvent.

[Comparative Example 1]
(Copper nano paste)
Copper fine particles not subjected to oxidation treatment and glycerin as a solvent were mixed to prepare a copper nano paste having a copper concentration of 50 wt% and a glycerin concentration of 50 wt%.

(Circuit board)
Two copper electrodes having a thickness of 100 μm □ and a thickness of 20 μm were arranged on the epoxy resin substrate at an interval of 400 μm on the same surface.

(Connection procedure)
(A) Copper fine particle oxidation degree In copper nanopaste, the intensity ratio (H2 / (H1 + H2)) of Cu peak height H1 and Cu ₂ O peak height H2 in the XRD method spectrum was measured.

(B) Sintered layer oxygen concentration (atomic number concentration)
After firing the copper nanopaste, the sintered copper layer was cut and the cross section corresponding to the following position was weighed by the EDX method to obtain an oxygen concentration.
Sintered body average: Any three locations (average value) excluding substrate vicinity and electrode vicinity
Near the substrate: a position 5 μm away from the interface between the copper sintered body and the substrate In the vicinity of the electrode: a position 5 μm away from the interface between the copper sintered body and the substrate in the thickness direction

[Comparative Examples 2 to 4]
Measurement and evaluation were performed in the same manner as Comparative Example 1 except that copper fine particles subjected to oxidation treatment and glycerin were mixed to prepare a copper nanopaste having a copper concentration of 50 wt% and a glycerin concentration of 50 wt%.

[Comparative Example 5]
The same procedure as in Comparative Example 1 was conducted except that copper fine particles subjected to oxidation treatment and NMP (N-methyl-2-pyrrolidone) were mixed to produce a copper nanopaste having a copper concentration of 50 wt% and an NMP concentration of 50 wt%. Measured and evaluated.

Tables 1 and 2 show the results of measurement and evaluation by the above method.

  As shown in Tables 1 and 2, in Examples 1 to 8, it was found that both the resin substrate and the glass substrate had a resistance value between the conductors of 1.0 Ω or less, indicating good electrical connectivity. Further, in the pencil scratch test, it was found that the hardness was 5H or less on both the substrate and the conductor, and no peeling occurred and excellent substrate adhesion and conductor adhesion were exhibited.

  On the other hand, in Comparative Example 1, the resistance value between the conductors was 10Ω, and it was found that the electrical connectivity was inferior. Further, in the pencil scratch test, it was found that peeling occurred at a hardness of 10B on the substrate and the substrate adhesion was poor. In Comparative Example 2, it was found that the resistance value between the conductors was 7Ω, and the electrical connectivity was inferior. Moreover, although peeling did not generate | occur | produce with hardness 2B or less, it turned out that it is inferior to board | substrate adhesiveness. In Comparative Example 3, the resistance value between the conductors was 5Ω, and it was found that the electrical connectivity was inferior. Moreover, although peeling did not generate | occur | produce below hardness HB on a board | substrate, it turned out that it is inferior to board | substrate adhesiveness. In Comparative Example 4, it was found that the resistance value between the conductors was 4Ω, and the electrical connectivity was inferior.

  Although the comparative example 5 was a case where the solvent which does not contain a polyol was used, it turned out that between conductors became non-conducting and it did not have electrical connectivity. Moreover, peeling occurred at a hardness of 10B on both the substrate and the conductor, and it was found that there was no substrate adhesion and no conductor adhesion.

DESCRIPTION OF SYMBOLS 1 Board | substrate 1a Main surface 2 Copper conductor 2a Upper surface 2b Side surface 3 Copper sintered body 5 Board | substrate 5a Main surface 5b Inner peripheral surface 6 Copper conductor 6a Inner side surface 7 Copper sintered body 31 Board | substrate contact part 32 Conductor contact part 31a contact Surface 32a Contact surface 71 Conductor contact portion 72 Substrate contact portion 71a Contact surface 72a Contact surface

Claims (7)

A plurality of copper conductors forming at least part of the circuit on the substrate;
A copper sintered body connecting the plurality of conductors,
The copper sintered body has a substrate contact portion that contacts the substrate, and a conductor contact portion that contacts the copper conductor,
The oxygen concentration in the copper sintered body is less than 10% in terms of the average atomic number concentration measured by the EDX method,
The connection structure according to claim 1, wherein an oxygen concentration of the substrate contact portion is higher than an oxygen concentration of the conductor contact portion. The oxygen concentration of the substrate contact portion is more than 6% and not more than 10% in terms of atomic concentration measured by the EDX method.
2. The connection structure according to claim 1, wherein the oxygen concentration of the conductor contact portion is 1% or more and 6% or less in terms of the atomic number concentration measured by the EDX method. The plurality of copper conductors and the copper sintered body are formed on the substrate,
A part of the copper sintered body is formed so as to cover at least a part of the plurality of copper conductors and a part of the substrate,
The connection structure according to claim 1, wherein the substrate contact portion is disposed on the substrate, and the conductor contact portion is disposed on the copper conductor. The copper sintered body is formed so as to fill in a through hole provided penetrating in the thickness direction of the substrate,
The copper conductor is disposed so as to cover both end faces of the copper sintered body formed in the through hole,
The said board | substrate contact part is arrange | positioned in contact with the internal peripheral surface of the said through-hole, and the said conductor contact part is arrange | positioned in contact with the said copper conductor, The said 1 or 2 characterized by the above-mentioned. Connection structure.   The connection structure according to claim 1, wherein a thickness of the substrate contact portion is 10 μm or less. A copper particle-containing paste for forming a copper sintered body that connects between a plurality of copper conductors, forming at least part of a circuit on a substrate,
In the X-ray diffraction measurement, when the peak height of the Cu diffraction spectrum is H1, and the peak height of the Cu ₂ O diffraction spectrum is H2, the X-ray diffraction peak intensity ratio (H2 / [H1 + H2]) is 0. 8 or more 86 or less, copper particles whose surface layer is made of copper oxide,
A polyol having two or more hydroxyl groups in the molecule as a solvent;
The copper particle containing paste characterized by containing.   The polyol is ethylene glycol, diethylene glycol, glycerin, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-butene- 1,4-diol, pentanediol, hexanediol, octanediol, 1,1,1-trishydroxymethylethane, 2-ethyl-2-hydroxymethyl-1,3-propanediol, 1,2,6-hexanetriol , 1,2,3-hexanetriol, 1,2,4-butanetriol, one selected from the group consisting of threitol, erythritol, pentaerythritol, xylitol, sorbitol, pentitol, terpineol and hexitol Or two or more types To claim 6 of a copper particle-containing paste.

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