JP5451365B2 - Wiring board manufacturing method - Google Patents

Description

  The present invention relates to a method of manufacturing a wiring board applied to a package for housing semiconductor elements and a high-frequency module, in which ceramic green sheets with embedded wiring patterns are stacked and fired, and to the wiring board.

  In recent years, along with miniaturization of electronic devices used in the field of mobile communication, etc., miniaturization and high performance have been desired for wiring boards used in these electronic devices.

  Such a wiring board is made by adding an organic binder, a plasticizer and a solvent to a ceramic powder to form a slurry, forming a ceramic green sheet by a doctor blade method or the like, and then printing a conductor paste containing a metal powder. A ceramic green sheet laminate is obtained by forming a wiring pattern on the ceramic green sheet and then laminating and pressing the ceramic green sheets on which a plurality of wiring patterns are formed. It is obtained by firing.

  However, when the thickness of the ceramic green sheet is reduced and the number of laminated ceramic green sheets is increased in order to meet the above-described requirements for the wiring board, the wiring patterns formed between the layers of different ceramic green sheets overlap in the lamination direction. The thickness difference between the region and the region that does not overlap with the region increases. For this reason, when pressure is applied to produce a ceramic green sheet laminate, a sufficient amount of pressure is applied in areas where wiring patterns formed between layers of different ceramic green sheets overlap in the stacking direction, but in areas where they do not overlap Since the applied pressure is difficult to be applied sufficiently, insufficient pressure bonding tends to occur. And when the ceramic green sheet laminated body formed by such insufficient pressure bonding is fired, delamination (delamination) may occur in a portion where pressure bonding is insufficient.

  On the other hand, in the above ceramic green sheet laminate, it is necessary to increase the thickness of the wiring pattern in order to reduce the DC resistance value which is an important electrical characteristic. However, there is a problem that delamination is more likely to occur when the thickness of the wiring pattern is increased.

  For these problems, a wiring pattern made of a conductive paste is printed on a support film by a screen printing method, etc., and a ceramic slurry is applied thereon, followed by heating and drying, and then the support film adhered. A method of manufacturing a ceramic green sheet with a wiring pattern, which is characterized in that the wiring pattern is transferred to the ceramic green sheet by peeling off (see Patent Document 1).

  According to this manufacturing method, since the surface of the ceramic green sheet on which the wiring pattern is formed can be flattened by embedding the wiring pattern with the conductor paste in the ceramic green sheet, different ceramic green sheets are laminated. There is no difference in thickness between the area where the wiring patterns formed between the green sheet layers overlap and the area where they do not overlap in the stacking direction, and it is possible to suppress the occurrence of delamination due to uneven pressure.

  However, according to the manufacturing method described in Patent Document 1, since the release agent layer is easy to repel without absorbing the solvent contained in the conductor paste, the wiring pattern of the conductor paste is screened on the support film. When forming by a printing method or the like, there is a problem that printing bleeding occurs.

JP-A-9-283360 JP 2007-160643 A

  Here, in order to enable printing without blurring, as described in Patent Document 2, it is melted by applying heat at the time of print transfer and can be cured at room temperature after wiring pattern transfer. It is conceivable to use a conductor paste containing the composition. The hot melt composition is a solid that maintains a constant shape at room temperature, but melts when given constant heat and has fluidity (melts).

  However, in the method using the conductive paste containing the hot melt composition, the hot melt composition is melted by the heat in the process of applying the ceramic slurry and then heating and drying to maintain the shape of the wiring pattern. It was difficult to do.

  The present invention has been made to solve the above-described problems, and is a wiring board that suppresses occurrence of delamination and suppresses deformation of a wiring pattern containing a hot melt composition due to melting. An object is to provide a manufacturing method and a wiring board.

  The method for manufacturing a wiring board of the present invention includes a step of forming a wiring pattern with a conductive paste containing a conductor powder and a hot melt composition on a support film, and covering the wiring pattern and the exposed upper surface of the support film. Forming a film of a first ceramic slurry containing a first ceramic powder and a thermosetting resin that cures at a temperature lower than the melting temperature of the hot melt composition, and curing the thermosetting resin; The second ceramic slurry containing the second ceramic powder and the organic binder having the same composition as the first ceramic powder and having an average particle size larger than that of the first ceramic powder is applied to the coating of the first ceramic slurry. The wiring pattern is coated so that a flat upper surface is formed by covering the upper surface and partially varying the thickness. Forming a ceramic green sheet with a wiring pattern embedded in a ceramic green sheet on the support film, peeling the support film from the ceramic green sheet with the wiring pattern, and ceramic green with the wiring pattern It comprises a step of stacking a plurality of sheets to produce a laminate and a step of firing the laminate.

  According to the method for manufacturing a wiring board of the present invention, the first ceramic slurry coating containing a thermosetting resin that cures at a temperature lower than the melting temperature of the hot melt composition so as to cover the wiring pattern and the exposed support film. And the step of curing the thermosetting resin prevents the wiring pattern containing the hot melt composition from being melted and deformed by the heat during drying and causing delamination. Can be suppressed.

It is explanatory drawing of the manufacturing method of the wiring board of this invention, (a) represents the state by which the wiring pattern by the conductor paste was formed on the support film, (b) showed the wiring pattern and exposure on the support film. A state in which a film made of the first ceramic slurry is formed so as to cover the support film is represented, (c) represents a state in which a ceramic green sheet with a wiring pattern is formed on the support film, and (d) represents a ceramic with a wiring pattern. The state which peeled the support film from the green sheet represents, and (e) represents the state which laminated | stacked multiple ceramic green sheets with a wiring pattern, and produced the laminated body.

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

  In the method for manufacturing a wiring board according to the present invention, first, as shown in FIG. 1A, a wiring pattern 2 is formed on a support film 1 using a conductor paste containing a conductor powder and a hot melt composition.

  The support film 1 includes a support film body 11 and a release agent layer 12 formed on the upper surface.

  The support film body 11 has a role as a support for forming a ceramic green sheet with a wiring pattern on the upper surface after the release agent layer 12 is formed on the upper surface. Examples thereof include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyimide that are excellent in mechanical strength, heat resistance, etc., but polyethylene terephthalate (PET) is desirable in consideration of cost. The thickness of the support film body 11 is preferably about 50 to 100 μm, particularly 50 to 60 μm from the viewpoint of maintaining mechanical strength, preventing deformation, and cost.

  The release agent layer 12 is used to peel the support film body 11 and the release agent layer 12 together from a ceramic green sheet with a wiring pattern, which will be described later. However, it is desirable to use a silicone-based resin, and the thickness is desirably 10 to 50 nm so that sufficient releasability required can be maintained.

  The conductor paste that forms the wiring pattern 2 contains a conductor powder and a hot melt composition. For example, when the ceramic insulating layer constituting the wiring board to be manufactured is made of alumina, the conductive powder such as W or Mo is the main component, and the ceramic insulating layer constituting the wiring board to be manufactured is made of glass ceramics. Uses a conductive powder such as Cu or Ag as a main component, a hot melt composition mixed therein, and further added with additives such as plasticizer, glass and filler.

  Here, the hot melt composition is a solid that maintains a constant shape at room temperature, but melts when given constant heat, and has fluidity (melts). . As such a hot melt composition, the molecular weight, crystallinity, etc. are adjusted so that it has fluidity (melts) with heat of about 40 ° C. to 100 ° C. from the relationship with the temperature at which the wiring pattern 2 is formed. It is preferable to use a thermoplastic resin that has been adjusted so as to have fluidity (melt) with a heat of 40 to 60 ° C. in consideration of the thermal effect on the substrate.

  Examples of the thermoplastic resin include polyethylene resins such as low density polyethylene, medium density polyethylene, high density polyethylene, and linear low density polyethylene; α-olefin copolymers other than ethylene-ethylene; ethylene-ethyl acrylate Polymers, ethylene-alkyl (meth) acrylate copolymers such as ethylene-n-butyl acrylate copolymer, ethylene-methyl methacrylate copolymer; ethylene-vinyl acetate copolymer; polypropylene resin; α other than propylene-propylene -Olefin copolymer: Styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene-butylene-styrene obtained by hydrogenating these diene moieties block Examples include block copolymers such as copolymers (SEBS) and styrene-ethylene-propylene-styrene block copolymers (SEPS). The copolymers may be random copolymers, and block copolymers. It may be. These thermoplastic resins may be used alone or in combination of two or more.

  The plasticizer is an ester compound synthesized from an acid and an alcohol. Examples of the acid include phthalic acid, trimellitic acid, and adipic acid. Examples of the alcohol include octanol, nonanol, and higher mixed alcohols. Specifically, dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), di-normal octyl phthalate (DNOP), diisononyl phthalate (DINP), phthalate Examples thereof include phthalic acid esters such as dinonyl acid (DNP), dioctyl adipate (DOA), and diisononyl adipate (DINA).

  For the formation of the wiring pattern 2, screen printing, ink jet printing, offset printing, and the like can be adopted. However, it is desirable to use a screen printing method in terms of pattern formation tact surface and equipment cost. In the case of the screen printing method, a conductive paste containing hot melt resin can be applied by heating to about 40 to 120 ° C. at the time of printing using a squeegee and a mask embedded with heating lines. The wiring pattern 2 can be formed on the support film 1 by removing the mask and solidifying the conductive paste as the temperature of the hot melt resin decreases. Note that the wiring pattern 2 is usually formed to a width of 10 to 500 μm and a thickness of 2 to 50 μm.

  Next, as shown in FIG. 1B, thermosetting is performed at a temperature lower than the melting temperature of the first ceramic powder and the hot melt composition so as to cover the upper surface of the wiring pattern 2 and the exposed support film 1. The film 3 made of the first ceramic slurry containing the curable resin is formed to cure the thermosetting resin.

  The coating 3 made of the first ceramic slurry has a role of preventing the wiring pattern 2 containing the hot melt composition from being melted and deformed by heat when drying the second ceramic slurry described later. The coating 3 made of the first ceramic slurry contains a thermosetting resin that cures at a temperature lower than the melting temperature of the hot melt composition. That is, this thermosetting resin covers the wiring pattern 2 and the exposed support film 1 because the wiring pattern 2 is already cured when the wiring ceramics 2 are melted by heat when drying the second ceramic slurry described later. Thus, even if the wiring pattern 2 is melted by the heat at the time of drying the second ceramic slurry, the coating 3 made of the first ceramic slurry breaks its shape. Therefore, the deformation of the wiring pattern 2 can be suppressed.

  Here, as the thermosetting resin that is cured at a temperature lower than the melting temperature of the hot melt composition, the hot melt composition has a molecular weight and fluidity so as to have fluidity (melt) with a heat of about 40 ° C. to 100 ° C. Since a thermoplastic resin with adjusted crystallinity and the like is used, a thermosetting resin that cures at a temperature from room temperature (about 25 ° C.) to less than 40 ° C. is exemplified. Specifically, an epoxy resin or an alkyd resin is used. Can be mentioned. These may be used alone or in combination, and a curing agent (crosslinking agent) such as a polyamine or a hydrazide compound may be added.

  The first ceramic powder has the same composition as the second ceramic powder contained in the second ceramic slurry described later. For example, when the second ceramic powder is alumina powder, the first ceramic powder is also alumina powder. With this configuration, changes in porcelain characteristics and shrinkage mismatch can be suppressed.

  In addition, the average particle size of the first ceramic powder is smaller than the average particle size of the second ceramic powder contained in the second ceramic slurry, which will be described later, because the coating 3 made of the first ceramic slurry is thinly applied. Specifically, the thickness is 0.1 to 1 μm. With this configuration, the conductor component contained in the wiring pattern 2 can be prevented from diffusing during firing, and the insulation can be improved.

  For forming the coating 3 with the first ceramic slurry, various coaters such as spraying, gravure coater, reverse gravure coater, Mayer bar coater, die coater, reverse roll coater, phanten reverse roll coater, kiss roll coater, etc. The coating method 3 by the first ceramic slurry is usually formed to a thickness of 1 to 30 μm.

  And as a method of curing the thermosetting resin, it may be allowed to stand at room temperature for several hours, but in consideration of manufacturing in a short time, a range from room temperature (about 25 ° C.) to less than 40 ° C. It is preferable to cure by heating, and a curing agent may be added to the first ceramic slurry and cured.

  Next, as shown in FIG. 1C, a second ceramic slurry containing the second ceramic powder having the same composition as the first ceramic powder and a larger average particle diameter than the first ceramic powder and an organic binder. The wiring pattern 2 is coated so as to cover the upper surface of the coating 3 made of the first ceramic slurry and to form a flat upper surface by partially varying the thickness, and the wiring pattern 2 is embedded in the ceramic green sheet 4 A patterned ceramic green sheet 5 is produced on the support film 1.

  The second ceramic slurry includes a second ceramic powder having the same composition as the first ceramic powder and an average particle size larger than that of the first ceramic powder, and an organic binder.

  The second ceramic powder is made of, for example, alumina powder, silica powder, glass powder, and the like. As described above, when the second ceramic powder is alumina powder, the first ceramic powder is also alumina powder. And the average particle diameter of 2nd ceramic powder is larger than the average particle diameter of 1st ceramic powder mentioned above, for example, is suitably determined in the range of 1-10 micrometers.

  Examples of the organic binder include acrylic homopolymers or copolymers (homopolymers or copolymers of acrylic acid, methacrylic acid or their esters, specifically acrylic ester copolymers, methacrylate esters). Polymer, acrylic ester-methacrylic ester copolymer, etc.), homopolymers or copolymers such as polyvinyl butyral, polyvinyl alcohol, acrylic-styrene, polypropylene carbonate, and cellulose.

  In addition, in the second ceramic slurry, for example, an organic solvent such as ethers, esters, ketones, alcohols, or the like is used so that an appropriate viscosity can be obtained by dispersing the second ceramic powder and the organic binder. Terpineol, dimethyl phthalate, butyl carbitol acetate, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, dibutyl phthalate, and the like are added. Further, a dispersant may be added in order to make the dispersion better.

  As a method for applying the second ceramic slurry, a method using a doctor blade, a lip coater, a die coater or the like is used.

  In addition, the second ceramic slurry is dried to form the ceramic green sheet 4. In this drying step, the temperature of 40 ° C. to 70 ° C., particularly 50 ° C. Heating at a temperature of 65 ° C is preferred. At this time, the hot-melt composition once melts, but solidifies again when cooled after the completion of drying.

  Although not shown in the figure, when a laminate 6 described later is manufactured, it is formed on the support film 1 so as to connect the wiring patterns 2 formed on the ceramic green sheets 5 with different wiring patterns. A through hole penetrating the ceramic green sheet 5 with a wiring pattern is formed by a micro drill, a laser, or the like, and the through hole is filled with a conductor paste for a through conductor. As the through-conductor paste, a conductor powder similar to the conductor powder contained in the conductor paste forming the wiring pattern 2 is used. For example, a paste obtained by adding an organic binder, an organic solvent, or the like to the conductor powder is used.

  Next, as shown in FIG.1 (d), the support film 1 is peeled from the ceramic green sheet 5 with a wiring pattern.

  Specifically, the ceramic green sheet 5 with a wiring pattern is fixed by vacuum suction or the like, and is peeled from any one of the four corners of the support film 1 at a constant speed. Due to the peelability of the release agent layer 12, the release agent layer 12 and the ceramic green sheet 5 with the wiring pattern can be peeled cleanly.

  Next, as shown in FIG.1 (e), the laminated body 6 is produced by laminating | stacking several ceramic green sheets 5 with a wiring pattern.

  The lamination is performed by applying heat and pressure to the stacked ceramic green sheets 5 with wiring patterns, or by applying an adhesive composed of an organic binder, plasticizer, solvent, etc. between the ceramic green sheets 5 with wiring patterns. Then, a thermocompression bonding method or the like can be employed. In addition, the conditions of the heating and pressing at the time of lamination | stacking change with kinds and quantity of organic binders etc. to be used, for example, set to 30-100 degreeC and 2-20 MPa.

  Finally, the laminate 6 is fired.

  Specifically, when the wiring pattern 2 is made of W or Mo material and the ceramic green sheet 4 is made of alumina material, firing is performed at a firing temperature of 1300 to 1600 ° C. in a reducing atmosphere. When the wiring pattern 2 is made of a Cu material and the ceramic green sheet 4 is made of a glass ceramic material, firing is performed at a firing temperature of 800 to 1000 ° C. in a nitrogen reducing atmosphere, and the wiring pattern 2 is made of an Ag material and ceramic. When the green sheet 4 is made of a glass ceramic material, firing is performed at a firing temperature of 800 to 1000 ° C. in an air atmosphere.

  In addition, the above-mentioned hot melt composition and thermosetting resin are burned away by firing.

  By the above manufacturing method, a plurality of ceramic insulating layers in which wiring is embedded on one main surface side are laminated, a portion of the ceramic insulating layer that contacts the side surface of the wiring, a portion that contacts the bottom surface, and one main surface The first ceramic crystal particles included in a nearby portion have the same composition as the second ceramic crystal particles included in other portions of the ceramic insulating layer and have an average particle size larger than that of the second ceramic crystal particles. A wiring board characterized by being small can be obtained.

  That is, by forming the coating 3 made of the first ceramic slurry, the obtained wiring board is included in a portion that contacts the side surface of the wiring in the ceramic insulating layer, a portion that contacts the bottom surface, and a portion near one main surface. The first ceramic crystal particles are of the same composition as the second ceramic crystal particles contained in other parts of the ceramic insulating layer and have an average particle size smaller than that of the second ceramic crystal particles.

  Such a wiring board is suppressed from the occurrence of delamination and becomes a wiring board having good insulation provided with wiring formed with high accuracy.

1: Support film 11: Support film body 12: Release agent layer 2: Wiring pattern 3: Coating with first ceramic slurry 4: Ceramic green sheet 5: Ceramic green sheet with wiring pattern 6: Laminate

Claims (1)

Forming a wiring pattern with a conductive paste containing a conductive powder and a hot melt composition on a support film;
A first ceramic slurry containing a first ceramic powder and a thermosetting resin that cures at a temperature lower than the melting temperature of the hot melt composition so as to cover the wiring pattern and the exposed upper surface of the support film. Forming and curing the thermosetting resin;
The second ceramic slurry containing the second ceramic powder and the organic binder having the same composition as the first ceramic powder and having an average particle size larger than that of the first ceramic powder is applied to the coating of the first ceramic slurry. A ceramic green sheet with a wiring pattern in which the wiring pattern is embedded in the ceramic green sheet is coated on the support film so as to cover the upper surface and partially vary in thickness to form a flat upper surface. A manufacturing process;
Peeling the support film from the ceramic green sheet with a wiring pattern; and stacking a plurality of ceramic green sheets with the wiring pattern to produce a laminate;
And a step of firing the laminated body.

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