JP6144052B2 - Film-coated substrate and method for forming the same - Google Patents

Description

  The present invention relates to a film forming method and a film.

  Conventionally, screen printing, contact dispenser, spin coating have been used as a method for forming a “film comprising at least a metal powder or ceramic powder, an organic binder, and a solvent” on a film forming surface having a step in a substrate. A method, a die coater method, a dip coating method, a tape attaching method and the like are widely known.

  However, the above-mentioned various methods have problems such as “a large variation in film thickness is likely to occur particularly in a portion across a level difference” and “a relatively large film thickness cannot be obtained by a single film formation process”. there were.

  Furthermore, if the film thickness is relatively large when the film thickness is relatively large, there is a problem that cracks and peeling (hereinafter referred to as “cracks”) occur in the film during the subsequent drying / firing process. (It will be described later in detail. See FIG. 7 described later).

  By the way, in recent years, a method of forming a film on the film forming surface by discharging a plurality of liquid droplets onto the film forming surface using a device that discharges liquid as droplets (droplet discharging device, inkjet dispenser) ( A droplet discharge method and an ink jet method are widely known (see, for example, Patent Documents 1 to 3). By adopting this droplet discharge method, it is possible to obtain a relatively large film thickness by a single film formation process as compared with the above-mentioned various methods, and the variation in film thickness also in the portion across the step. Can be small.

  The present inventor uses this droplet discharge method to dry and apply a “film comprising at least a metal powder or ceramic powder and an organic binder” on the film forming surface having a step in the substrate. The present inventors have found a condition in which cracks and the like are hardly generated in the film during the firing process.

JP 2010-115577 A JP 2003-80694 A Japanese Patent Laid-Open No. 2003-136991

  That is, the present invention provides a film forming method for forming a film on a film forming surface having a step in a substrate by using a droplet discharge method, which does not easily cause cracks in the film during the drying and baking process. The purpose is to do.

  In the film forming method according to the present invention, using a droplet discharge device, a precursor solution containing at least a metal powder or ceramic powder, an organic binder, and a solvent is formed into a plurality of droplets, and a “film forming surface having a step in the substrate” is formed. Are discharged and landed at a plurality of different positions in the film formation region including the step, thereby forming a film in the film formation region of the film formation surface.

  Here, “a plurality of droplets are ejected and landed at a plurality of different positions in the film formation region” means that the film formation is completed by one film formation process. More specifically, it means that liquid droplets are not repeatedly ejected or landed (at least twice) at the same position in the film formation region. In other words, it means that the film thickness is determined based on the size of a single droplet (not the thickness of the stacked droplets).

  The height of the step is h, and “the distance between an arbitrary point on the surface of the formed film and the intersection of the normal to the surface of the film extending from the arbitrary point and the film forming surface” Is the film thickness at the arbitrary point, Δt is the difference between the maximum value and the minimum value of the film thickness in the dried state of the film, and the minimum value of the film thickness in the dried state of the film is tmin. Then, in the film forming method according to the present invention, when the relationship of tmin> (2/3) h is established, the relationship of Δt ≦ 0.15h is established. The “state after drying” refers to the state after the drying step and before the firing step. Hereinafter, the “film after drying” is also referred to as “dry film”.

  Here, in the state of the dry film, it is preferable that the relationship of tmin ≧ 6.5 μm is established. In addition, when the distance between the centers of adjacent droplets landed on the film formation surface is called “pitch”, the pitch is larger than the diameter of the droplets (value before landing) and after landing In order for the droplets of each of the above to expand naturally in the plane direction due to the action of gravity (so-called “leveling” progresses), the adjacent droplets are connected, so that the pitch, the diameter of the droplets, the droplets It is preferable that the viscosity and the like are adjusted.

  As will be described later, the present inventor, when the relationship of tmin> (2/3) h is established, the case where the relationship of Δt ≦ 0.15h is established, compared with the case where it is not, drying / calcination It was found that cracks and the like were hardly generated in the film during the process (see Table 1 described later).

  Furthermore, as will be described later, the present inventor, when the volume ratio of the portion excluding the metal powder or ceramic powder among the components constituting the dry film is 25% or more, compared to the case where it is not so, It has been found that cracks and the like are hardly generated in the film during the drying / firing process (see Table 2 described later).

  Further, as will be described later, the present inventor has found that the porosity of the substrate constituting the film forming surface is 0 before the film is dried (before the drying process, more precisely before the film forming process). It has been found that cracks and the like are not particularly likely to occur in the film during the drying / firing process when it is greater than 50% and less than or equal to 50% (see Table 3 below).

Moreover, it is preferable that the viscosity of the precursor solution stored in the droplet discharge device is 1 × 10 ⁵ cP or less at room temperature. According to this, the progress of leveling becomes easy, and the variation in film thickness can be reduced.

It is the schematic diagram which showed an example of the structure of the nozzle hole vicinity of the droplet discharge apparatus which can be used with the film | membrane formation method which concerns on embodiment of this invention. It is the schematic diagram which showed the other example of the structure of the nozzle hole vicinity of the droplet discharge apparatus which can be used with the film | membrane formation method concerning embodiment of this invention. The process from the stage where droplets are ejected and landed on the film forming surface to the stage where the film (ie, the film before the drying / firing process) is formed (completed) on the film forming surface as the leveling progresses It is the schematic diagram which showed. It is the schematic diagram which showed an example in case a film | membrane (namely, dry film) is formed ranging over the said level | step difference on the film | membrane formation surface which has one level | step difference. It is the schematic diagram which showed an example in case a film | membrane (namely, dry film) is formed ranging over the said level | step difference on the film | membrane formation surface which has a level | step difference of multiple steps (this example 3 steps). It is the schematic diagram which expanded and showed an example of the periphery of a level | step difference in case a film | membrane (namely, film | membrane before a drying and baking process) is formed across a level | step difference on a film | membrane formation surface by a screen printing method. FIG. 7 is a schematic diagram showing an example of how cracks occur in the subsequent drying / firing process in the film shown in FIG. 6. FIG. 7 is a schematic diagram corresponding to FIG. 6 in a case where a film (that is, a dry film) is formed across a step on a film forming surface by the film forming method according to the embodiment of the present invention.

  Hereinafter, a film forming method according to an embodiment (this embodiment) of the present invention and a film formed by the film forming method will be described.

(Outline of film forming method according to this embodiment)
In the present embodiment, a technique (liquid solution) is formed by ejecting a plurality of droplets onto a film formation surface of a substrate using a droplet ejection device (inkjet dispenser) that ejects liquid as droplets. Droplet discharge method, ink jet method) is employed. The substrate is made of, for example, a fired body, a molded body before firing, a metal, a resin, or the like.

  As the droplet discharge device A applied to the present embodiment, for example, as shown in FIG. 1, “a vibrator is vibrated inside a storage chamber in which a precursor solution containing a component that forms a film is stored. 2, and having a form in which droplets are ejected from fine nozzle holes communicating with the storage chamber, or as shown in FIG. 2, “a vibration that defines the storage chamber in which the precursor solution is stored. And the like having a form in which droplets are ejected from fine nozzle holes communicating with the storage chamber by vibrating the plate by driving a piezoelectric element. As the droplet discharge device A, a device having a format other than the above-described format may be employed.

  As shown in FIG. 3A, in the present embodiment, at room temperature, above the flat substrate (position away from the substrate in the z-axis positive direction) and downward (z-axis negative direction). The liquid droplets are ejected at a predetermined cycle while the nozzle holes of the liquid droplet ejection apparatus A are translated along the film formation surface at a predetermined relative speed with respect to the upper surface (film formation surface) of the substrate. As a result, the respective droplets land and adhere to different positions in sequence within the film formation region on the film formation surface.

  Each droplet after landing naturally spreads in the xy plane direction by the action of gravity on the film forming surface in the order of landing (so-called leveling proceeds). As a result, a film having a small variation in film thickness is formed on the film formation surface (see FIG. 3B). The film thickness (minimum value) of the film formed in this manner is preferably 6.5 μm or more after drying (after the drying process described later and before the firing process).

  Hereinafter, the distance (pitch) between the centers of adjacent droplets landed on the film forming surface is P, and the diameter (value before landing) of the discharged droplets is D (FIG. 3A). See). In the example shown in FIGS. 3A to 3B, adjacent droplets are separated immediately after landing due to P being larger than D (FIG. 3A), but the subsequent leveling proceeds. In the process, adjacent droplets are connected (FIGS. 3A and 3B). On the other hand, adjacent droplets may be connected immediately after landing due to P being smaller than D. Note that P can be adjusted by controlling the droplet discharge period and the relative movement speed of the nozzle hole with respect to the film formation surface. D can be adjusted by controlling the nozzle diameter as well as the viscosity of the precursor solution.

  In FIG. 3A, when only a movement of the nozzle hole in the y-axis direction relative to the film formation surface is used, a plurality of liquid droplets are attached only in a line along the y-axis direction on the film formation surface. It is shown. In this case, the film formation region has an elongated shape that is narrow in the x-axis direction and wide in the y-axis direction when viewed from the positive z-axis direction. On the other hand, by appropriately combining the movement of the nozzle hole in the x-axis direction and the movement in the y-axis direction with respect to the film formation surface, a plurality of liquid droplets are formed in a matrix in the xy plane direction on the film formation surface. May be attached. In this case, the film formation region can have a wide shape in both the x-axis direction and the y-axis direction when viewed from the positive z-axis direction.

  In the present embodiment, formation of a film (that is, a film before firing) is completed by a single film formation process. More specifically, liquid droplets are not repeatedly ejected or landed at the same position in the film formation region (twice or more times). In other words, as shown in FIGS. 3A to 3B, the thickness of the film formed on the film formation surface is not a single droplet (rather than the thickness of a plurality of stacked droplets). It can be said that it is determined based on the size.

  The film shown in FIG. 3B is then subjected to a drying / firing process. In the drying process, the membrane is exposed to an environment of 35 to 120 ° C. for 0.2 to 1.5 hours. As a result, the solvent component contained in the film is removed by evaporation, the film is dried, and the dry film is formed. In the firing step, the dried film is fired at 750 to 1600 ° C. for 1 hour or longer. As a result, the organic binder or the like contained in the dry film is burned out, and a film as a final form (that is, a fired film) is completed.

(Components of precursor solution)
The precursor solution used in this embodiment includes at least a metal powder or ceramic powder, an organic binder, and a solvent, and also includes a plasticizer, a dispersant, a rheology control agent, and the like as necessary. As the metal powder, for example, powders of palladium, platinum, gold, silver, copper, nickel, tungsten, molybdenum, and powders made of these alloys can be used. These metal powders may be used alone or in combination of two or more. Examples of the ceramic powder include metal oxides such as aluminum oxide, zirconium oxide, nickel oxide, iron oxide, copper oxide, lanthanum oxide, cerium oxide, chromium oxide, and titanium oxide, and nitride such as aluminum nitride, titanium nitride, and silicon nitride. Product powders can be used. The particle size of the powder is 0.1 to 20 μm. As the organic binder, for example, cellulose-based or phenolic resins such as butyral-based, acrylic-based, ethylcellulose, and methylcellulose can be used. Examples of the solvent include ketones such as acetone, methyl ethyl ketone, dipropyl ketone, and diisobutyl ketone, alcohols such as ethanol, isopropanol, butanol, and 2-ethylhexanol, aromatic hydrocarbons such as toluene and xylene, and methyl propionate. , Ethyl propionate, butyl propionate, methyl butanoate, ethyl butanoate, butyl butanoate, methyl pentanoate, ethyl pentanoate, butyl pentanoate, methyl hexanoate, ethyl hexanoate, butyl hexanoate, 2-ethylhexyl acetate, Esters such as 2-ethylhexyl butyrate, methyl cellosolve, ethyl cellosolve, butyl cellosolve, terpineol, butyl carbitol, butyl carbitol acetate, and the like can be used. These organic solvents may be used alone or in combination of two or more. Examples of the plasticizer include phthalic acid derivatives, isophthalic acid derivatives, tetrahydrophthalic acid derivatives, adipic acid derivatives, maleic acid derivatives, fumaric acid derivatives, trimellitic derivatives, pyromellitic derivatives, stearic acid derivatives, oleic acid derivatives, itaconic acid. Derivatives and ricinol derivatives can be used, and phthalic acid derivative plasticizers are particularly preferred. Specifically, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, di- (2-ethylhexyl) phthalate, dioctyl phthalate, diisooctyl phthalate, diisobutyl phthalate, diheptyl phthalate, diphenyl phthalate and the like can be used. As the dispersant, for example, a polymer compound having an affinity for the metal powder or ceramic powder surface can be used. The content of each component is 15 to 45% by volume of metal powder or ceramic powder, 7 to 25% by volume of organic binder, 35 to 73% by volume of solvent, 3 to 20% by volume of plasticizer, and 2 to 2 of dispersant. 15% by volume. The viscosity of the precursor solution is preferably 1 × 10 ⁵ cP or less at room temperature. Thereby, the progress of the leveling can be facilitated, and the variation in film thickness can be reduced.

(Conditions for suppressing cracks)
In the present invention, it is assumed that there is a step on the film formation surface of the substrate and a film is formed on the film formation surface so as to straddle the step. As shown in FIG. 4, not only when the film is formed so as to straddle the step on the film forming surface having one step, but as shown in FIG. It may be assumed that the film is formed so as to straddle the step on the film forming surface having the step. In the case shown in FIG. 5, the materials of the plurality of substrates constituting the plurality of steps may be different. In this case, the material of the substrate (film formation surface) is different between the upper side and the lower side of the step.

  Incidentally, conventionally, as a method for forming a film on a film forming surface having a step (surface of the substrate), a screen printing method or the like is widely known in addition to the droplet discharge method employed in the present embodiment. However, in the screen printing method or the like, as shown in FIG. Specifically, in the example shown in FIG. 6, the height of the step on the surface of the film (the difference in height in the z-axis direction) is the height of the step on the film formation surface (the surface of the substrate) (the difference in height in the z-axis direction). ) Is small. As a result, the film thickness on the right side of the step is larger than the film thickness on the left side.

  As described above, when a film having a large variation in film thickness in a portion across the step is subjected to a drying / firing process, the film is likely to crack in the step portion as shown in FIG. Alternatively, separation may occur at the interface between the film and the film formation surface at the stepped portion. These cracks and delamination are caused by large stresses in the film at the stepped part due to the fact that a large difference in film shrinkage due to a large difference in film thickness occurs locally at the stepped part during drying and firing. Is thought to be based on local occurrence.

  On the other hand, if the droplet discharge method is employed as in the present embodiment, as shown in FIG. 8, the variation in film thickness in the portion across the step can be reduced as compared with the screen printing method or the like. . Hereinafter, as shown in FIG. 8, the height of the step on the film formation surface (the difference in height in the z-axis direction) is assumed to be h. The film thickness t at an arbitrary point on the surface of the film is a distance between “an arbitrary point on the surface of the film” and “the intersection of the normal to the film surface extending from the arbitrary point and the film forming surface”. (See FIG. 8). Further, regarding the entire surface of the film after the drying process and before the baking process (that is, the dried film), the maximum value and the minimum value in the distribution of the film thickness t are tmax and tmin, respectively, and the difference between tmax and tmin (film) Let Δt be the variation in thickness.

  As the maximum value Tmax and the minimum value tmin, “when viewed from the positive z-axis direction (direction perpendicular to the film formation surface), the center of gravity is the same as the shape of the film formation region and the area is 80%. Only the film thickness within the “similar shape region” is considered. In other words, the film thickness at the “periphery of the film forming region” outside the region having the similar shape is not considered as the maximum value Tmax and the minimum value tmin. The step is included in the region having the similar shape.

  In the case where a film is formed on a film forming surface having a step using the droplet discharge method, the present inventor satisfies Δt ≦ 0.15h under the condition that the relationship of tmin> (2/3) h is established. When the relationship is established, it was found that cracks are less likely to occur in the film during the drying / firing process than when the relationship is not. Hereinafter, test A in which this has been confirmed will be described.

(Test A)
In test A, using the film forming method according to the present embodiment described above, 12 types of patterns (with no droplets discharged twice or more at the same position in the film forming region) by one film forming process (that is, Level), a film (that is, a film before the drying / firing process) was formed on the film forming surface having a step in the substrate, and then the film was subjected to the drying / firing process. The combinations of Δt, tmim, and h in each pattern are as shown in Table 1. There were 10 samples (N = 10) for each pattern. The relationship of tmin ≧ 6.5 μm was established for each pattern. Further, the relationship of tmin> (2/3) h was established.

  In each pattern, a plurality of liquid droplets are formed on the film forming surface in the y-axis direction by appropriately combining the movement of the nozzle hole in the x-axis direction and the movement in the y-axis direction relative to the film forming surface at room temperature. Along multiple rows. As a result, the film formation region was a rectangular parallelepiped when viewed from the positive z-axis direction. In each pattern, the droplet diameter D is in the range of 60 to 400 μm, and the pitch P between the droplets (in each of the x-axis direction and the y-axis direction) is in the range of 100 to 1000 μm (where P> D). Adjusted respectively. As a result, in each pattern, adjacent droplets were separated immediately after landing (FIG. 3A), but adjacent droplets were connected in the process of subsequent leveling (FIG. 3 ( a) (b)).

In each pattern, a fired body or a molded body before firing was used as the substrate. Silver was used as the “metal powder or ceramic powder”. The particle size of the powder was 0.1 to 20.0 μm. Ethyl cellulose was used as the organic binder. Butyl carbitol acetate was used as the solvent. Dioctyl phthalate was used as the plasticizer. DISPERBYK-2095 (manufactured by Big Chemie Japan Co., Ltd.) was used as the dispersant. The content ratio (volume ratio) of each component was 25% by volume for silver, 15% by volume for the organic binder, 49% by volume for the solvent, 5% by volume for the plasticizer, and 6% by volume for the dispersant. The viscosity of the precursor solution was 1 × 10 ⁵ cP or less at room temperature. The viscosity of the precursor solution was measured using a 1 ° 34 ′ × R24 rotor of an E-type viscometer (product number: TV-25) manufactured by Toki Sangyo Co., Ltd. at a rotational speed of 5 rpm and at room temperature (25 ° C.). It was done. The adjustment of the film thickness t (tmin) was achieved by adjusting the diameter D of the droplet (that is, adjusting the nozzle diameter, the viscosity of the precursor solution, etc.) and the pitch. Also, the adjustment of the film thickness variation Δt was achieved by adjusting the relationship between D and P and the viscosity of the precursor solution.

  And about each pattern, the film | membrane (namely, film | membrane before drying and baking) was used for the drying and baking process. In the drying process, the membrane was exposed to an environment of 35 to 120 ° C. for 0.2 to 1.5 hours. As a result, the solvent component inside the film was removed by evaporation. In the firing step, the film was fired at 750 ° C. to 900 ° C. for over 1 hour. As a result, the organic binder or the like inside the film was burned out, and a film as a final form (ie, a fired film) was completed. Then, for each pattern, it was determined whether or not a crack occurred in the step portion. This determination was made based on visual observation or observation using a microscope. The results are as shown in Table 1.

  As can be understood from Table 1, when attention is paid to Δt / h, when the relationship of Δt / h> 0.15 is satisfied under the condition of tmin> (2/3) h, the crack occurrence rate is larger than zero. When the relationship of Δt / h ≦ 0.15 was established, the crack occurrence rate was zero. The crack occurrence rate is a ratio of “the number of cracks in all the samples” to “the total number of samples” for each pattern. As described above, when the relationship of tmin> (2/3) h is established, the film is cracked during the drying / firing process when the relationship of Δt / h ≦ 0.15 is established, as compared with the case where it is not. It can be said that is difficult to occur.

  Hereinafter, in the state after the film is dried (after the drying process and before the firing process), the volume ratio of the component constituting the film excluding “metal powder or ceramic powder” is defined as P (%). When the relationship of Δt ≦ 0.15h is satisfied under the condition that the relationship of tmin> (2/3) h is satisfied, the present inventor determines that P ≧ 25% during the subsequent drying / firing process. It has also been found that cracks and the like are less likely to occur in the film. Hereinafter, test B in which this has been confirmed will be described.

(Test B)
Also in Test B, a film (that is, a dry film) was formed on a film forming surface having steps with 12 types of patterns (levels) by the same procedure as in Test A. The combinations of Δt, tmim, h, and P in each pattern are as shown in Table 2. About 10 samples (N≈10) existed for each pattern. For each pattern, a relationship of tmin ≧ 6.5 μm was established, and a relationship of tmin> (2/3) h was established. For each pattern, Δt / h ≦ 0.15 was established. As in Test A, a fired body or a molded body before firing was used as the substrate.

  And about each pattern, the film | membrane (namely, film | membrane before drying and baking) was used for the drying and baking process on the same conditions as the test A except drying and baking conditions. In the drying process, the membrane was exposed to an environment of 120 ° C. to 140 ° C. for 0.2 to 0.5 hours. In the firing step, the film was fired at 900 ° C. to 1000 ° C. for 1 hour or more. That is, as the drying / firing condition, a condition that is thermally severer than that in the case of Test A was adopted. Then, for each pattern, it was determined whether or not a crack occurred in the step portion. The results are as shown in Table 2.

  As can be understood from Table 2, under the condition that the relationship of tmin> (2/3) h is satisfied, when the relationship of Δt ≦ 0.15h is satisfied, the case where P ≧ 25% is compared with the case where it is not And the crack generation rate is small. From the above, when the relationship of Δt ≦ 0.15h is satisfied under the condition that the relationship of tmin> (2/3) h is satisfied, the case where P ≧ 25% is compared with the case where it is not so, the drying / firing It can be said that cracks are less likely to occur in the film during the process.

  Hereinafter, the porosity of the substrate will be examined. The present inventor has determined that the pores of the substrate at the stage before drying of the film (before the drying process) when the relationship of Δt ≦ 0.15h is satisfied under the condition that the relationship of tmin> (2/3) h is satisfied. It has also been found that when the rate is greater than 0% and 50% or less, cracks and the like are less likely to occur in the film during the subsequent drying and firing steps. Hereinafter, test C in which this has been confirmed will be described.

(Test C)
In Test C, a film (that is, a dry film) was formed on a film forming surface having a step in 12 types of patterns (levels) by the same procedure as in Test A. Table 3 shows combinations of Δt, tmim, h, and substrate porosity in each pattern. As the porosity of the substrate, the value before the film formation process was adopted. About 10 samples (N≈10) existed for each pattern. For each pattern, a relationship of tmin ≧ 6.5 μm was established, and a relationship of tmin> (2/3) h was established. For each pattern, Δt / h ≦ 0.15 was established. As in Test A, a fired body or a molded body before firing was used as the substrate.

  And about each pattern, the film | membrane (namely, film | membrane before drying and baking) was used for the drying and baking process on the same conditions as the test A except drying and baking conditions. In the drying process, the membrane was exposed to an environment of 120 ° C. to 140 ° C. for 0.2 to 0.5 hours. In the firing step, the film was fired at 900 ° C. to 1000 ° C. for 1 hour or more. That is, as the drying / firing condition, a condition that is thermally severer than that in the case of Test A was adopted. Then, for each pattern, it was determined whether or not a crack occurred in the step portion. The results are as shown in Table 3.

  As can be understood from Table 3, when the relationship of Δt ≦ 0.15h is satisfied under the condition that the relationship of tmin> (2/3) h is satisfied, the porosity of the substrate (the stage before the film forming process) ) Is greater than 0% and less than or equal to 50%, the crack occurrence rate is small as compared to the case where it is not. As described above, when the relationship of Δt ≦ 0.15h is satisfied under the condition that the relationship of tmin> (2/3) h is satisfied, the porosity of the substrate (stage before drying of the film) is greater than 0% and 50 When the content is less than or equal to%, it can be said that cracks are less likely to occur in the film during the drying / firing process than in the other cases.

  Here, “additional reason why if the porosity of the substrate (the stage before the film forming process) is large, cracks are likely to occur in the film during the drying / firing process” will be added. If the porosity of the substrate is large before the film is formed, the solvent component contained in the film is easily absorbed into the pores of the substrate. As the solvent component is absorbed into the pores of the substrate, the concentration of the solvent component inside the film decreases and the viscosity of the film increases. When the viscosity of the film increases, the progress of the leveling is hindered, and a film with a large variation in film thickness is formed. When the variation in the film thickness is large, local stress concentration occurs in the film during the subsequent drying and baking processes, and cracks are likely to occur in the film. Based on the above mechanism, it is considered that “if the porosity of the substrate (the stage before the film formation process) is large, cracks are likely to occur in the film during the drying / firing process”.

  In this test A (Table 1), test B (Table 2), and test C (Table 3), silver is used as the metal powder or ceramic powder, but powder of other materials is used. It has been confirmed that the same results as above can be obtained. In this test A (Table 1), test B (Table 2), and test C (Table 3), the relationship of tmin ≧ 6.5 μm was established, but tmin <6.5 μm. It has been confirmed that the same results as above can be obtained.

  In addition, this invention is not limited to the said embodiment, A various modification can be employ | adopted within the scope of the present invention. For example, in the example shown in FIG. 8 and the like, the step on the film formation surface has a shape having a relatively gentle slope, but the step on the film formation surface may have a step shape. In the example shown in FIG. 8, the level difference on the film formation surface is one step. However, as shown in FIG. 5, the level difference on the film formation surface may be a plurality of levels. In this case, the relationship described above (the relationship between Δt, tmin, and h) is applied to each step.

Claims (9)

Is formed on the film formation region including the step of film forming surface having a step in the substrate, and to a substrate having metal powder or ceramic powder, and comprising at least a structure membrane of an organic binder,
Height of the step is h (5μm ≦ h ≦ 250μm) ,
The distance between an arbitrary point on the surface of the film and the intersection of the normal to the surface of the film extending from the arbitrary point and the film forming surface is a film thickness at the arbitrary point,
The difference between the maximum value and the minimum value of the film thickness in the dried state of the film is Δt,
When the minimum value of the film thickness in the state after drying of the film is tmin,
A substrate having a film , wherein a relationship of tmin> (2/3) h is established and a relationship of Δt ≦ 0.15h is established. A substrate having the film of claim 1,
A substrate having a film , wherein a relation of tmin ≧ 6.5 μm is established in a state after the film is dried. In the substrate having the film according to claim 1 or 2,
The board | substrate which has a film | membrane whose volume ratio of the part except the said metal powder or ceramic powder among the components which comprise the said film | membrane in the state after the said film | membrane dried is 25% or more. In the board | substrate which has a film | membrane as described in any one of Claims 1 thru | or 3,
The board | substrate which has a film | membrane whose porosity of the board | substrate which comprises the said film formation surface is 0% or more and 50% or less in the state before the said film | membrane dried. Using a droplet discharge device, a precursor solution containing at least a metal powder or a ceramic powder, an organic binder, and a solvent is used as a plurality of droplets, and a film forming surface having a step difference in the substrate is different in the film forming region including the step. A film forming method for forming a film in a film forming region of the film forming surface by discharging each of a plurality of positions,
The height of the front Symbol step is h (5μm ≦ h ≦ 250μm) ,
The distance between an arbitrary point on the surface of the formed film and the intersection of the normal to the surface of the film extending from the arbitrary point and the film forming surface is a film thickness at the arbitrary point,
The difference between the maximum value and the minimum value of the film thickness in the dried state of the film is Δt,
When the minimum value of the film thickness in the state after drying of the film is tmin,
droplets are ejected so that a relationship of tmin> (2/3) h is established and a relationship of Δt ≦ 0.15h is established.
Method for forming substrate with film. In the formation method of the board | substrate with a film | membrane of Claim 5,
A method for forming a substrate with a film, wherein a relationship of tmin ≧ 6.5 μm is established in a state after the film is dried. In the formation method of the board | substrate with a film | membrane of Claim 5 or Claim 6,
A method for forming a substrate with a film, wherein in a state after the film is dried, a volume ratio of a component excluding the metal powder or ceramic powder among components constituting the film is 25% or more. In the formation method of the board | substrate with a film | membrane as described in any one of Claim 5 thru | or 7,
In the state before drying of the membrane, the porosity of the substrate of the film forming surface is 50% or less than 0%, the method of forming the film-coated substrate. In the formation method of the substrate with a film according to any one of claims 5 to 8,
A method for forming a film -coated substrate, wherein the precursor solution stored in the droplet discharge device has a viscosity of 1 × 10 ⁵ cP or less at room temperature.

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