JP2019041022A - Wiring substrate manufacturing method and conductive paste - Google Patents

Abstract

A wiring board manufacturing method and a conductive paste capable of suppressing the oxidation of copper as a wiring material and manufacturing a wiring board by a simple process.
In the first step, a paste for paste formation and at least one resinate of Si, Ti, Al, and B are added to an inorganic powder containing at least Cu and a conductive paste is added. Produced. In the second step, the wiring pattern 13 was formed on the green sheet 11 using a conductive paste. In the third step, another green sheet was laminated on the green sheet 11 on which the wiring pattern 13 was formed to produce a laminate, and the laminate 15 was degreased in an oxidizing atmosphere. In the fourth step, after degreasing, the wiring pattern 13 and the green sheet 11 constituting the laminated body 15 were simultaneously fired to obtain the wiring substrate 1 provided with the CuW wiring 5 in the ceramic substrate 3.
[Selection] Figure 2

Description

  The present disclosure relates to a method for manufacturing a wiring board that can be used in, for example, an electronic component package, a wireless communication module substrate, a control circuit substrate, a semiconductor inspection apparatus, and the like, and a conductive paste that can be used in the manufacturing method.

  Conventionally, when forming wiring on the surface or inside of a wiring board, a conductive paste is used. As this conductive paste, a conductive paste containing a conductive filler such as copper (Cu) powder in a paste component (for example, a vehicle) made of a resin binder and a solvent is known.

  When wiring is formed using this type of conductive paste (for example, copper-based paste containing copper powder), for example, a copper-based paste is applied on a ceramic green sheet to form a wiring pattern, and the ceramic green sheet and the wiring are formed. The pattern was fired simultaneously. That is, for example, at the time of simultaneous firing, the copper powder in the copper-based paste is sintered to form the wiring. Therefore, high oxidation resistance and sinterability are required for the copper powder to be used.

  Specifically, when heating the copper paste, an inert gas atmosphere is usually adopted, but in order to sufficiently remove the resin and solvent in the copper paste, some oxygen is contained in the inert gas. Therefore, the surface of the copper powder may be oxidized when the wiring is formed. When the surface of the copper powder is oxidized, the particle surface is covered with copper oxide, so that the sinterability is deteriorated and the conductivity of the formed wiring is also lowered.

As countermeasures, for example, techniques described in Patent Documents 1 and 2 below have been proposed.
Patent Document 1 discloses a technique for improving oxidation resistance and sinterability by covering the surface of a copper powder with a SiO ₂ -based gel coating film containing 5% by weight or less of Si. In this technique, a predetermined Si compound or the like is added to a suspension containing copper powder to form a SiO ₂ -based gel coating film on the surface of the copper powder, and then, for example, at 120 ° C. for 11 hours or more in a nitrogen atmosphere. By heating and drying, a copper powder having a SiO ₂ -based gel coating film is produced.

  Further, in Patent Document 2, in order to improve oxidation resistance and the like, copper powder is immersed in a solution containing boron (B) and then heated at a temperature of 50 to 260 ° C. A technique for forming a boron film on the surface is disclosed.

JP 2004-149817 A JP-A-5-195260

By the way, the above-described conventional technology has the following problems, and improvements have been demanded.
Specifically, when preparing a copper-based paste, copper powder is prepared in advance, but in order to increase the oxidation resistance of the copper powder, etc., when a film containing Si or B is formed on the surface of the copper powder. Since a film is formed by heat treatment, a process for producing a copper powder having a film is required. As a result, there has been a problem that man-hours and manufacturing costs for manufacturing a wiring board increase.

  This indication is made in view of the above-mentioned subject, and the object is that it can control the oxidation of copper which is the material of wiring, and can manufacture a wiring board by a simple process, and It is to provide a conductive paste.

  (1) According to a first aspect of the present disclosure, an inorganic powder containing at least Cu is added with a paste component for pasting, and at least one resinate among Si, Ti, Al, and B to conduct electricity. A step of producing a paste (for example, a first step), a step of forming a wiring pattern on a green sheet using a conductive paste (for example, a second step), and degreasing the green sheet on which the wiring pattern is formed in an oxidizing atmosphere A process to be performed (for example, a third process), and a process of simultaneously firing the wiring pattern and the green sheet (for example, a fourth process) after degreasing.

  In the present disclosure, in the first step, the paste for paste formation and at least one resinate among Si, Ti, Al, and B are added to the inorganic powder containing at least Cu, and the conductive paste. Is made.

Thereby, while the inorganic powders, such as Cu, disperse | distribute in the component for paste, the electrically conductive paste of the state which the said resinate adhered to the surface of the inorganic powder is obtained.
In the second step, a wiring pattern is formed on the green sheet using the conductive paste.

  In the third step, the green sheet on which the wiring pattern is formed is degreased in an oxidizing atmosphere. At the time of this degreasing, it is presumed that at least one metal component of Si, Ti, Al, and B out of the resinate adhering to the periphery of Cu is oxidized to cover the periphery of Cu. That is, it is estimated that the periphery of Cu is covered with the oxide film of the metal component.

  In the fourth step, the wiring pattern and the green sheet are simultaneously fired after degreasing. In this simultaneous firing, it is considered that the oxidation of Cu is suppressed by the oxide film of the metal component around Cu.

Thus, in this indication, since a wiring board is manufactured by processing of the 1st-the 4th process, there are few man-hours which manufacture a wiring board, and there is an effect that manufacturing cost can be reduced.
That is, conventionally, when manufacturing Cu powder to be added to the conductive paste, a coating of Si or B is formed around the Cu powder, and heat treatment at a high temperature is required when forming the coating. However, in the present disclosure, since the heat treatment for forming a coating film on the Cu powder is unnecessary before the Cu powder is added to the conductive paste, a remarkable effect that the man-hours and costs at the time of manufacture can be greatly reduced. Play.

  In the present disclosure, since the resinate is added to the conductor paste, the amount of the metal component used for improving the oxidation resistance of Cu is added to the case of forming a film on the conventional Cu powder. Small amount is enough. Therefore, there is an advantage that performance such as resistance of the formed wiring is excellent. Further, when the wiring is formed by firing, there is an effect that the influence on the sinterability of the wiring is small.

(2) In the second aspect of the present disclosure, 0.5 to 3.0% by weight of resinate may be added to the inorganic powder.
As will be described later, by adding resinate to the inorganic powder in the range of 0.5 to 3.0% by weight, the resistance of the wiring (specific resistance value) can be reduced, and the wiring board is fired. The amount of deformation at the time can be suppressed.

In addition, here, the case where it adds in external weight% with respect to inorganic powder in metal conversion, such as Si in resinate, is shown.
(3) In the third aspect of the present disclosure, Si resinate may be used as the resinate.

  Here, an example suitable as a resinate is shown. By using this Si resinate, the resistance (specific resistance value) of the wiring can be reduced, and the deformation amount when the wiring substrate is baked can be suppressed.

(4) A fourth aspect of the present disclosure relates to a conductive paste used for forming a wiring.
This conductive paste includes an inorganic powder containing at least Cu, a paste component for forming a paste, and at least one resinate among Si, Ti, Al, and B.

  By using the conductive paste, it is possible to reduce the man-hours for manufacturing the wiring substrate and to reduce the manufacturing cost. Further, by using this conductor paste, the amount of the metal component used for improving the oxidation resistance of Cu can be small. Therefore, there is an advantage that performance such as resistance of the formed wiring is excellent. Further, when the wiring is formed by firing, there is an effect that the influence on the sinterability of the wiring is small.

(5) In the fifth aspect of the present disclosure, the resinate may be included in an amount of 0.5 to 3.0% by weight with respect to the inorganic powder.
By using this conductive paste, the resistance (specific resistance value) of the wiring can be reduced, and the deformation amount when the wiring board is fired can be suppressed.

In addition, here, the case where it adds in external weight% with respect to inorganic powder in metal conversion, such as Si in resinate, is shown.
(6) In the sixth aspect of the present disclosure, Si resinate may be contained as the resinate.

  Here, an example suitable as a resinate is shown. By using this Si resinate, the resistance (specific resistance value) of the wiring can be reduced, and the deformation amount when the wiring substrate is baked can be suppressed.

<Each component of the present disclosure will be described below>
In addition to Cu, examples of inorganic powder include W and Mo.
-As a component for paste, an organic binder and a solvent are mentioned. Examples of the organic binder include ethyl cellulose and butyral, and examples of the solvent include terpineol, butyl carbitol, and texanol. Resin is a metal organic compound (organometallic compound; specifically, an organometallic complex), and here Then, at least one resinate among Si, Ti, Al, and B is used. For example, at least one of Si resinate, Ti resinate, Al resinate, and B resinate can be used.

  A green sheet is an unfired sheet that contains an inorganic component that becomes solid after firing, such as a ceramic material, and becomes a ceramic substrate after firing. The ceramic substrate has ceramic as a main component (that is, a component having the largest volume%).

Examples of the inorganic component include a ceramic component, a sintering aid that promotes ceramic sintering, and a glass component. Examples of the ceramic component include alumina, mullite, cordierite, and the like. Examples of the sintering aid include SiO ₂ , MgCO ₃ , BaCO _{3 and the} like. During sintering, the sintering aid is vitrified.

It is sectional drawing which fractures | ruptures and shows the wiring board of embodiment to the thickness direction. It is explanatory drawing which shows the manufacturing method of the wiring board of embodiment. (A) is a graph showing a TG-DTA curve of Cu powder, (b) is a graph showing a TG-DTA curve of Si, (c) is a graph showing a TG-DTA curve of Ni, and (d) is a TG of Co. -A graph showing a DTA curve. (A) is a graph showing a TG-DTA curve of Ti, (b) is a graph showing a TG-DTA curve of B, and (c) is a graph showing a TG-DTA curve of Al. It is sectional drawing which shows the cross section of the sample of the unbaking stage used for Experimental example 2. FIG. (A) Sectional drawing which shows the cross section of the sample of the unbaking stage used for Experimental example 3, (b) is the top view. It is sectional drawing which shows the cross section of the sample of the unbaking stage used for Experimental example 4. FIG. 10 is a SEM photograph showing a cross section of a part of the sample of Experimental Example 5. 10 is a SEM photograph showing a cross section of another part of the sample of Experimental Example 5.

Next, a method for manufacturing a wiring board of the present disclosure and an embodiment of a conductive paste used for the manufacturing method will be described.
[1. Embodiment]
[1-1. Wiring board configuration]
First, the wiring board of the embodiment will be described.

As schematically shown in FIG. 1, a wiring substrate 1 of the embodiment includes a CuW electrode (wiring) 5 containing Cu and W as main components inside a ceramic substrate 3 containing, for example, 90% by volume or more of Al ₂ O _3. It is equipped with. Here, vias and other wirings are omitted.

Among these, the ceramic substrate 3 includes a first ceramic layer 7 and a second ceramic layer 9, and a CuW wiring 5 is disposed between the first ceramic layer 7 and the second ceramic layer 9.
In addition to Al ₂ O ₃ , the ceramic substrate 3 contains components of a sintering aid such as SiO ₂ , MgCO ₃ , BaCO ₃ , for example.

The CuW wiring 5 includes components such as Al ₂ O _{3 in} addition to Cu and W which are conductive components.
[1-2. Wiring board manufacturing method]
Next, the principal part of the manufacturing method of the wiring board 1 of this embodiment is demonstrated based on FIG.

<Preparation process>
First, Al ₂ O ₃ powder was prepared as a main raw material (raw material as a main component) of the ceramic substrate 3, and a powder of a sintering aid was prepared. And a ceramic slurry was produced by adding a binder, a solvent, etc. to these powder materials. The green sheet 11 was produced using this ceramic slurry.

<First step>
In the first step, an inorganic powder containing at least Cu (for example, Cu, W, a sintering aid), a paste component (for example, a binder, a solvent) for forming a paste, and Si, Ti, Al, and B At least one resinate (for example, Si resinate) was added to produce a conductive paste.

The resinate is added in an external weight percent (for example, in terms of Si) of 0.5 to 3.0 weight percent with respect to the inorganic powder.
<Second step>
In the second step, the wiring pattern 13 was formed on the green sheet (ceramic green sheet) 11 using a conductive paste.

<Third step>
In the third step, another green sheet is laminated on the green sheet 11 on which the wiring pattern 13 is formed to produce a laminate, and the laminate 15 is subjected to a temperature range (for example, 250 ° C. to 200 ° C.) in an oxidizing atmosphere. Deg.).

<4th process>
In the fourth step, after degreasing, the wiring pattern 13 and the green sheet 11 constituting the laminated body 15 were simultaneously fired to obtain the wiring substrate 1 provided with the CuW wiring 5 in the ceramic substrate 3.

[1-3. effect]
(1) In this embodiment, since the wiring board 1 is manufactured by the above-described processes, the number of steps for manufacturing the wiring board 1 can be reduced, and the manufacturing cost can be reduced.

  That is, conventionally, when manufacturing Cu powder to be added to the conductive paste, a coating of Si or B is formed around the Cu powder, and heat treatment at a high temperature is required when forming the coating. However, in this embodiment, since the heat treatment for forming a film on the conventional Cu powder is unnecessary, there is a remarkable effect that man-hours and costs at the time of manufacture can be greatly reduced.

  (2) Further, in this embodiment, for example, Si resinate is added to the conductor paste, so that the amount of Si component used for improving the oxidation resistance of Cu, for example, forms a film on the conventional Cu powder. In addition to that, a small amount is sufficient. Therefore, there is an advantage that the performance such as resistance of the formed CuW wiring 5 is excellent. Further, when the CuW wiring 5 is formed by firing, there is an effect that the influence on the sinterability of the CuW wiring 5 is small.

  (3) Particularly when 0.5 to 3.0% by weight of resinate is added to the inorganic powder, the resistance (specific resistance value) of the CuW wiring 5 can be greatly reduced, and the wiring board The amount of deformation when firing 1 can be sufficiently suppressed.

[1-4. Correspondence of wording]
Here, the correspondence between words will be described.
The wiring board 1, the green sheet 11, and the wiring pattern 13 of the embodiment correspond to examples of the wiring board, the green sheet, and the wiring pattern of the present disclosure, respectively.

[1-5. Experimental example]
Next, experimental examples performed using samples in the examples of the scope of the present disclosure and comparative examples outside the scope of the present disclosure will be described.

  In the following experiments, there are those using a wiring board before firing and a wiring board after firing, but as shown in Table 1 below, those using the same conductive paste are collected with the same sample number. It is displayed.

[1-5-1. Sample preparation method]
First, a method for producing a green sheet and a conductive paste for each sample used in the experiment will be described.

<Production of green sheet>
First, Al ₂ O ₃ powder as a main raw material was prepared as a ceramic raw material powder, and powders such as SiO ₂ , MgCO ₃ , BaCO ₃ were prepared as a sintering aid. The Al ₂ O ₃ powder was prepared with an average particle size of 0.5 μm and a specific surface area of 6.0 m ² / g.

Further, as a binder component and a plasticizer component for forming a sheet, a butyral binder (that is, butyral resin), DOP (di-octyl phthalate), and the like were prepared.
Next, 2500 g of these powder materials (one or more kinds of sintering aids are selected and used from the respective powders) were weighed into an Al ₂ O ₃ pot. After adding a predetermined amount of colorant, 300 g of butyral resin, an amount of solvent (ethanol, toluene) and an appropriate amount of plasticizer (DOP) necessary to give an appropriate slurry viscosity and sheet strength are added. did. The ceramic slurry was obtained by grinding and mixing in this pot for 20 hours.

  Next, a green sheet was prepared by a doctor blade method using the obtained ceramic slurry. In addition, 0.11 mm and 0.14 mm can be adopted as the thickness of the green sheet.

<Preparation of conductive paste>
Cu powder and W powder, which are conductive components, were prepared as inorganic components, and Al ₂ O ₃ powder was prepared as a ceramic component. Further, ethyl cellulose resin and tarpione as a solvent for dissolving this resin were prepared as paste components (varnish components), and they were mixed at a volume ratio of 15:85. Furthermore, Si resinate was prepared as a resinate.

These were put into an automatic revolution mixer and mixed, and then kneaded using a three-roll mill to obtain a conductive paste.
Note that in the inorganic powder, the Cu powder and a W powder and _Al 2 _{O 3} powder, 50 volume ratio: 50: was added at a ratio of 1. Further, as shown in Table 1 described later, the Si resinate was added in the range of 0.5 to 5% by weight based on the inorganic powder in terms of Si, based on the outer weight%.

A commercially available Si resinate was used as the Si resinate.
[1-5-2. Experiment contents]
<Experimental example 1>
This Experimental Example 1 is an investigation of the effect of suppressing the oxidation of Cu by using resinate.

  In Experimental Example 1, Cu powder was immersed in various resinate solutions as shown in FIGS. 3 and 4, specifically, Si resinate, Ni resinate, Co resinate, Ti resinate, B resinate, and Al resinate. The thing was stirred with the automatic revolution mixer and the solution of various resinate immersion Cu powder was produced.

  The supernatant of the resinate-immersed Cu powder solution was removed, and the remaining Cu powder was heated from room temperature (25 ° C.) to 500 ° C. at a heating rate of 5 ° C./min in the atmosphere by a TG-DTA analyzer. Thus, a TG-DTA curve was obtained.

  In addition, the TG-DTA curve which shows the change of a thermogravimetry (TG) and a differential thermal analysis (DTA) was calculated | required similarly to the sample of only Cu powder, without immersing Cu powder in resinate.

The results are shown in FIGS.
As shown in the TG graph of FIG. 3A, in the case of only Cu powder, the weight gradually increases from a range of 200 ° C. to 300 ° C. (temperature during degreasing). This is considered that the value of TG was increased by oxidation of Cu.

  As shown in the TG graph of FIG. 3 (b), when Cu powder is immersed in Si resinate, the weight decreases and does not increase in the range of 200 ° C to 300 ° C. This is considered that the oxidation of Cu is suppressed after the organic component is volatilized.

  As shown in the TG graph of FIG. 3C, when Cu powder is immersed in Ni resinate, the weight increases in the range of 200 ° C to 300 ° C. This is considered to be due to oxidation of Cu.

  As shown in the TG graph of FIG. 3D, when Cu powder is immersed in Co resinate, the weight increases from around 270 ° C. This is considered to be due to oxidation of Cu.

  As shown in the TG graph of FIG. 4A, when Cu powder is immersed in Ti resinate, the weight does not increase in the range of 200 ° C. to 300 ° C. This is considered because the oxidation of Cu is suppressed.

  As shown in the graph of TG in FIG. 4B, when Cu powder is immersed in B resinate, the weight does not increase in the range of 200 ° C. to 300 ° C. This is considered because the oxidation of Cu is suppressed.

  As shown in the TG graph of FIG. 4C, when Cu powder is immersed in an Al resinate, the weight does not increase in the range of 200 ° C. to 300 ° C. This is considered because the oxidation of Cu is suppressed.

  As is clear from Experimental Example 1, for example, at a temperature in the range of 200 ° C. to 300 ° C. (for example, a temperature during degreasing), Cu powder is added to each of Si resinate, Ti resinate, B resinate, or Al resinate solution. It is considered that the oxidation of Cu can be suppressed when immersed in the substrate.

<Experimental example 2>
In this experimental example 2, the effect of suppressing the oxidation of Cu by using Si resinate was investigated for each of Nos. 1 to 10 shown in Table 1 below.

Each sample having the shape shown in FIG.
Specifically, as shown in FIG. 5, two green sheets 21 prepared by the sample manufacturing method of the experimental example are stacked to prepare a stacked body 23, and a conductive paste corresponding to each sample is formed on the outermost surface thereof. Was applied to form a wiring pattern 25. The thickness of the wiring pattern 25 is 10 to 20 μm.

In addition, although the following Table 1 shows the additive and the addition amount of the conductive paste of Sample Nos. 1 to 10, Examples 1 to 5 are samples within the scope of the present disclosure, and Comparative Examples 1 to 5 are the present disclosure. The sample is out of the range.
Next, this laminate 23 was degreased at 250 ° C. for 5 hours in an air atmosphere.

Then, by performing XRD analysis of (X-ray diffraction analysis) relative to the wiring pattern 25 after degreasing was measured peak intensity in the strongest line of Cu and Cu 2 _O. The Cu oxidation rate was calculated from this peak intensity ratio (Cu ₂ O / Cu). The results are shown in Table 1 below.

  Further, apart from Examples 1 to 5, a conductive paste was prepared without adding Si resinate, and the wiring pattern was degreased at 500 ° C. in a nitrogen atmosphere or 250 ° C. in an air atmosphere. For the two samples, the Cu oxidation rate was calculated in the same manner.

  Furthermore, the Cu oxidation rate was calculated in the same manner for the samples of Comparative Examples 3 to 5 in which a conductive paste was prepared by simply immersing Cu powder in a solution to which Si powder was added, and degreased at 250 ° C. .

  As is clear from the Cu oxidation rate in Table 1, in Examples 1 to 5, the Cu oxidation rate was small and Cu oxidation was suppressed, which was preferable. On the other hand, in Comparative Examples 2-5, the oxidation rate of Cu is large and the oxidation of Cu is not suppressed so much. Since Comparative Example 1 is a nitrogen atmosphere, the Cu oxidation rate is small.

<Experimental example 3>
In Experimental Example 3, the resistance (specific resistance value) of the wiring of each sample was examined.
Each sample having the shape shown in FIG. 6 was prepared as a sample used in this Experimental Example 3.

  Specifically, as shown in FIG. 6, a laminate 33 was produced by laminating two green sheets 31 created by the sample production method of the experimental example. In addition, before laminating | stacking, the electrically conductive paste was apply | coated between both the green sheets 31, and the wiring pattern 35 used as wiring after baking was formed. The thickness of the wiring pattern 35 is 10 to 20 μm.

In Examples 1 to 5, the amount of Si resinate added in the conductive paste is the same as in Experimental Example 2 (see Table 1 below).
In addition, a pair of through holes 37 were formed in the upper green sheet 31 so as to communicate with the wiring pattern 35, and the through holes 37 were filled with molybdenum (Mo) paste for forming vias after firing. Further, a molybdenum paste was applied so as to cover the through hole 37, and an external electrode pattern 39 to be an external electrode after firing was formed.

Next, this laminate 33 was degreased at 250 ° C. for 5 hours in an air atmosphere.
Thereafter, the degreased laminated body 33 is fired at 1300 ° C. in a nitrogen-hydrogen mixed atmosphere, and includes a wiring and a via inside, and a wiring board having an external electrode (connected to the via) outside. A sample of was prepared.

  And the resistance value of the wiring of each sample was measured with the 4-terminal resistance value measuring machine. Specifically, the measurement distance of the internal wiring (distance between vias) and the thickness and width of the wiring were measured. The specific resistance value was determined from these measurement results. The results are shown in Table 1 below.

  In addition to Examples 1-5, as shown in Table 1 below, the conductive paste of Comparative Examples 1-5 similar to Experimental Example 2 was used as the conductive paste, and the method described in Experimental Example 3 was used. Samples of Comparative Examples 1 to 5 were prepared. And about this Comparative Examples 1-5, the specific resistance value was computed similarly.

  As is clear from the specific resistance values in Table 1, in Examples 1 to 4, the specific resistance value was small and suitable as a wiring. In Example 5, since the amount of Si resinate added is large, the specific resistance value is large.

<Experimental example 4>
In Experimental Example 4, the amount of warpage was examined as the amount of deformation of each sample.
Each sample having the shape shown in FIG. 7 was prepared as a sample used in this Experimental Example 4.

  Specifically, as shown in FIG. 7, three green sheets 41 created by the sample manufacturing method of the experimental example were laminated to produce a laminate 43. Prior to lamination, a conductive paste was applied between the upper and middle green sheets 41 to form a wiring pattern 45 to be a wiring after firing. The thickness of the wiring pattern 45 is 10 to 20 μm.

In Examples 1 to 5, the amount of Si resinate added in the conductive paste is the same as in Experimental Example 2 (see Table 1 below).
Next, this laminate 43 was degreased at 250 ° C. for 5 hours in an air atmosphere.

  Thereafter, this degreased laminate 43 was fired at 1300 ° C. in a nitrogen-hydrogen mixed atmosphere to prepare a sample of a wiring board having wiring therein. In this experimental example, the size of the wiring board is 55 mm long × 55 mm wide.

  And the amount of curvature was calculated | required with the laser 3D measuring machine made from Keyence with respect to the wiring board of each sample. The amount of warpage is the maximum amount of displacement from the surface of the base material when the wiring board is placed on the surface of the flat base material. The results are shown in Table 1 below.

  In addition to Examples 1-5, as shown in Table 1 below, the conductive paste of Comparative Examples 1-5 similar to Experimental Example 2 was used as the conductive paste, and the method described in Experimental Example 4 was used. Samples of Comparative Examples 1 to 5 were prepared. And about this Comparative Examples 1-5, the curvature amount was measured similarly.

  As is apparent from the warpage amount in Table 1, in Examples 1 to 4, the warpage amount was small and suitable as a wiring board. In Example 5, since the amount of Si resinate added is large, the amount of warpage is large.

<Experimental example 5>
In Experimental Example 5, the cross-sectional structure of each sample was observed.
Each sample (see FIG. 7) having the same shape as that in Experimental Example 4 was prepared as a sample used in Experimental Example 5.

And each sample (wiring board) of Examples 1-5 and Comparative Examples 1-5 was fractured | ruptured in the thickness direction so that wiring might be included, and the cross section was grind | polished.
Next, the structure | tissue was observed with the scanning electron microscope (SEM) made from JOEL with respect to the grind | polished cross section. Further, mapping observation of Si present in the wiring was performed using an electronic microanalyzer manufactured by JOEL.

  8 and 9 show SEM images (SEM photographs) at a magnification of 1500 times. As is clear from this SEM image, in the case of Examples 1 to 4, there was no void in the wiring, which was preferable. Moreover, in Example 5, since there was much addition amount of Si resinate, the space | gap was seen a little.

On the other hand, in Comparative Examples 3 to 5, not only voids but also SiO ₂ were observed in the wiring.

<Evaluation>
Next, the overall evaluation regarding Experimental Examples 1 to 5 will be described.

  By adding the material of the coating covering Cu with Si resinate, the oxidation rate of Cu was reduced and became equivalent to that of nitrogen degreasing. However, when added by Si powder, there is no effect of suppressing the oxidation of Cu even when 10 wt% is added.

This is because the Si resinate is formed so as to cover the Cu powder, so that it is oxidized prior to the oxidation of Cu to become SiO ₂ , and a SiO ₂ film is formed around the Cu powder, thereby suppressing the oxidation of Cu. It is thought that.

If too much Si resinate is added, the specific resistance value increases. This is thought to be because the SiO ₂ coating covering Cu was too thick to inhibit the firing of Cu. Since the firing of Cu is hindered, the firing shrinkage of the wiring (CuW electrode) does not progress, and the deviation from the firing shrinkage of the ceramic substrate is increased, so that the amount of warpage is also increased.

From the SEM image, there was a tendency for voids in the wiring to increase as the amount of Si resinate added was increased. This is presumed to be due to the fact that Si was inhibited from burning (flowing) by Si and that Si became SiO ₂ and wettability to the surrounding substrate was improved, so that Si escaped from the wiring. .

  In addition, when Si powder is added, it can be seen that it remains in the wiring unlike Si resinate. As a result, the firing of the wiring is hindered, which is considered to cause a phenomenon such as an increase in specific resistance value and a deterioration in warpage shape.

From these facts, it can be seen that the amount of Si resinate added is desirably in the range of 0.5 to 3.0% by weight of Si with respect to the inorganic powder, and is more desirably smaller.
[2. Other Embodiments]
As mentioned above, although embodiment of this indication was described, this indication is not limited to the above-mentioned embodiment, and can be carried out in various modes in the range which does not deviate from the gist of this indication.

  In addition, the function which one component in the said embodiment has may be shared by a some component, or the function which a some component has may be exhibited by one component. Moreover, you may abbreviate | omit a part of structure of the said embodiment. In addition, at least a part of the configuration of the above embodiment may be added to or replaced with the configuration of another embodiment. In addition, all the aspects included in the technical idea specified from the wording described in the claims are embodiments of the present disclosure.

DESCRIPTION OF SYMBOLS 1 ... Wiring board 5 ... Wiring 11, 21, 31, 41 ... Green sheet 13, 25, 35, 45 ... Wiring pattern

Claims (6)

A step of adding a paste component for forming a paste and at least one resinate of Si, Ti, Al, and B to an inorganic powder containing at least Cu to produce a conductive paste;
Using the conductive paste to form a wiring pattern on a green sheet;
Degreasing the green sheet on which the wiring pattern is formed in an oxidizing atmosphere;
A step of simultaneously firing the wiring pattern and the green sheet after the degreasing;
A method for manufacturing a wiring board, comprising: The resinate is added in an amount of 0.5 to 3.0% by weight based on the inorganic powder.
The manufacturing method of the wiring board of Claim 1. As the resinate, Si resinate is used.
The manufacturing method of the wiring board of Claim 1 or 2. In the conductive paste used to form the wiring,
An inorganic powder containing at least Cu; a paste component for pasting; and at least one resinate of Si, Ti, Al, and B.
Conductive paste. Containing 0.5 to 3.0 wt% of the resinate with respect to the inorganic powder;
The conductive paste according to claim 4. The resinate contains Si resinate,
The conductive paste according to claim 4 or 5.