JP5016401B2 - Multilayer insulation film - Google Patents

Description

  The present invention relates to a multilayer insulating film and a method for producing a wiring board using the same.

  2. Description of the Related Art In recent years, the performance, functionality, and miniaturization of electronic devices are rapidly progressing, and there is an increasing demand for miniaturization and weight reduction of electronic components used in electronic devices. Accordingly, multilayered printed wiring boards are required to be multilayered and thinned between layers.

  For example, in the production of a multilayer printed wiring board, when an insulating layer is formed on a conductor circuit pattern, the insulating resin is melted and then cured when the insulating layer is formed, whereby the conductor circuit is embedded in the insulating layer. However, as the wiring board becomes multilayered, the unevenness generated when the conductor circuit is embedded in the insulating layer is amplified, and the unevenness of the conductor circuit cannot be absorbed when forming the insulating layer, and the insulating layer becomes excessively thin. There was a risk that the insulation reliability would be lowered due to the formation of a portion.

  Therefore, when manufacturing a multilayer printed wiring board, there has been a demand for an insulating film that can be satisfactorily embedded in a gap or the like provided on a substrate and can maintain smoothness and insulating layer thickness as an insulating layer.

However, some techniques have been proposed, but the problem has not been solved (see, for example, Patent Document 1).
JP 11-87927 A

  An object of the present invention is to provide an insulating film that is satisfactorily embedded in a gap or the like provided on a substrate and that can maintain smoothness and insulating layer thickness as an insulating layer.

The present invention includes a base material, an epoxy resin laminated on the base material, an epoxy resin curing agent, a phenoxy resin having a polystyrene equivalent weight average molecular weight of 30,000 or more, an inorganic filler having an average particle diameter of 0.01 to 2 μm , a curing accelerator a including a first layer, a polystyrene-reduced weight average molecular weight of 30,000 or more phenoxy resins, a first layer comprising a first layer based on the total weight at 10 wt% or more, on the first layer stacked, epoxy resins, epoxy resin curing agent, average particle diameter 0.1~10μm of inorganic filler, and a second layer of curing accelerator, have a particle of the inorganic filler contained in the second layer The diameter is larger than the particle size of the inorganic filler contained in the first layer, and the amount of the curing accelerator contained in the first layer is larger than the amount of the curing accelerator contained in the second layer. The gist.

  ADVANTAGE OF THE INVENTION According to this invention, the insulating film which can be favorably embedded in the clearance gap etc. which were provided in the board | substrate, and can maintain the smoothness and insulating layer thickness as an insulating layer is provided.

  Hereinafter, the present invention will be described with reference to embodiments, but the present invention is not limited to the following embodiments. In addition, about what has the same function or a similar function in a figure, the same or similar code | symbol is attached | subjected and description is abbreviate | omitted.

(Multilayer insulation film)
The multilayer insulating film according to the embodiment includes a base material, an epoxy resin laminated on the base material, an epoxy resin curing agent, a phenoxy resin having a polystyrene-equivalent weight average molecular weight of 30,000 or more, and an average particle size of 0.01 to 2 μm. A first layer containing an inorganic filler, and a second layer containing an inorganic filler with an epoxy resin, an epoxy resin curing agent, and an average particle diameter of 0.1 to 10 μm laminated on the first layer. In addition, you may further have a protection sheet for prevention of adhesion, such as dust, which is disposed on the second layer so as to be peelable during use.

  The multilayer insulating film according to the embodiment is configured such that the particle size of the inorganic filler contained in the second layer is larger than the particle size of the inorganic filler contained in the first layer. As a result, for example, when a multilayer printed wiring board is manufactured using the multilayer insulating film according to the embodiment, even if the second layer is deformed following the unevenness of an element or the like provided on the substrate, the first layer is The shape of the first layer can be maintained without being deformed following the uneven shape of the substrate. As a result, it is possible to maintain smoothness as a multilayer insulating film while satisfactorily sealing gaps such as through holes and viewers provided in the substrate. Further, the insulating layer thickness can be maintained even when pressed with a press or the like. That is, the first layer ensures the thickness accuracy of the insulating layer after sealing and the smoothness of the insulating layer circuit formation surface, and the second layer ensures the filling property in a narrow gap during sealing. The multilayer insulating film according to the embodiment can be embedded in a relatively short time.

(Base material layer)
The substrate layer is not particularly limited. For example, a polyolefin film such as a polyester film such as a polyethylene terephthalate (PET) film, a polytetrafluoroethylene film, a polyethylene film, a polypropylene film, a polymethylpentene film, or a polyvinyl acetate film. A plastic film such as a plastic film, a polyvinyl chloride film, or a polyimide film can be used. A copper foil can also be used. Specifically, a transparent polyethylene terephthalate (PET) film (trade name “PET5011 550”, thickness 50 μm, manufactured by Lintec Corporation) can be used.

(1st layer, 2nd layer)
The raw materials used for the first layer and the second layer are listed below.

1. Epoxy resin Various epoxy resins can be used without any particular limitation. For example, biphenyl type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin can be used. Specifically, as the biphenyl-based epoxy resin, trade name “NC-3000”, epoxy equivalent 275, manufactured by Nippon Kayaku Co., Ltd., trade name “NC-3000H”, epoxy equivalent 288, manufactured by Nippon Kayaku Co., Ltd., Trade name “NC-3100”, epoxy equivalent 254, manufactured by Nippon Kayaku Co., Ltd. can be used. As the bisphenol A type epoxy resin, trade name “Epicoat 828US”, epoxy equivalent 183, Japan Epoxy Resin Co., Ltd. can be used. As the bisphenol F type epoxy resin, trade name “EPICLON830S”, epoxy equivalent 168, manufactured by Dainippon Ink & Chemicals, Inc. can be used. These epoxy resins may be used independently and 2 or more types may be used together.

2. Epoxy resin curing agent As the epoxy resin curing agent, various types can be used without particular limitation. Specifically, phenol-based curing agent (trade name “MEH7851-4H”, weight average molecular weight 10200 in terms of Pst, manufactured by Meiwa Kasei Co., Ltd.), active ester compound type curing agent (trade name “EXB-9451-65T”, Pst A weight average molecular weight 2840 in terms of conversion, manufactured by Dainippon Ink & Chemicals, Inc.) and dicyandiamide (trade name “EH-3636S”, manufactured by Asahi Denka Kogyo Co., Ltd.) can be used. These epoxy resin curing agents may be used alone or in combination of two or more.

3. Curing accelerator 1. In addition to the epoxy resin and 2. the epoxy resin curing agent, it is preferable to use a curing accelerator. Various curing accelerators can be used without particular limitation, and specifically, imidazole, triphenylphosphine, and the like can be used. These effect promoters may be used independently and 2 or more types may be used together.

4). Organized layered silicate As the layered silicate, various types can be used without particular limitation. Examples thereof include smectite clay minerals such as montmorillonite, hectorite, saponite, beidellite, stevensite and nontronite, swellable mica, vermiculite, and halloysite. Among these, at least one selected from the group consisting of montmorillonite, hectorite, swellable mica, and vermiculite is preferably used. These layered silicates may be used alone or in combination of two or more. When using a layered silicate, it is preferable to chemically modify the layered silicate to increase the affinity with the resin and to improve the dispersibility in the resin. By such chemical treatment, a large amount of layered silicate can be dispersed in the resin. The chemical modification method is also referred to as a cation exchange method using a cationic surfactant, and is a method in which cation exchange between layers of a layered silicate is performed with a cationic surfactant in advance to make it hydrophobic. By making the layers of the layered silicate hydrophobic beforehand, the affinity between the layered silicate and the resin is increased, and the layered silicate can be uniformly finely dispersed. In addition to performing an organic treatment on the layered silicate, a treatment with a fatty acid may be performed. This is because the layered silicate can be dispersed in the resin at a higher level, that is, so that the interlayer is in nanometer units.

Specific examples of the organic layered silicate include synthetic hectorite (trade name “Lucentite STN”, manufactured by Co-op Chemical Co., Ltd.) that has been chemically treated with trioctylmethylammonium salt.

  The addition amount of the organic layered silicate preferably includes the organic layered silicate in a proportion of 0.01 to 50 parts by weight with respect to 100 parts by weight of the total weight of the first layer. Moreover, it is preferable that the organic layered silicate is contained in a proportion of 0.01 to 50 parts by weight with respect to 100 parts by weight of the total weight of the second layer. It may be included in both the first layer and the second layer, or may be included in only one of them.

5. Inorganic filler As the inorganic filler, various types of inorganic fillers may be used without any limitation as long as the particle size of the inorganic filler contained in the second layer is larger than the particle size of the inorganic filler contained in the first layer. it can. The average particle diameter of the inorganic filler contained in the first layer is preferably 0.01 to 2 μm, and the average particle diameter of the inorganic filler contained in the second layer is preferably 0.1 to 10 μm. When a multilayer printed wiring board is manufactured using a multilayer insulating film, the first layer follows the uneven shape of the substrate even if the second layer deforms following the unevenness of the elements provided on the substrate. This is because the shape of the first layer can be maintained without being deformed. Examples of inorganic fillers include metals such as iron, copper, bronze, titanium, stainless steel, nickel, gold, silver, aluminum, lead, tungsten, carbon such as carbon black, graphite, activated carbon, carbon balloon, silica, silica Balloon, alumina, titanium oxide, iron oxide, zinc oxide, magnesium oxide, tin oxide, antimony oxide, beryllium oxide, barium ferrite, strontium ferrite and other inorganic oxides, aluminum hydroxide, magnesium hydroxide and other inorganic hydroxides, Inorganic carbonates such as calcium carbonate, magnesium carbonate and sodium hydrogen carbonate, inorganic sulfates such as calcium sulfate, talc, kaolin, fly ash, calcium silicate, glass, glass balloons and other inorganic silicates, calcium titanate, titanium Lead zirconate, aluminum nitride , Silicon carbide, heat-expandable vinylidene chloride particles, whiskers, and the like.

The particle size is defined by measuring with a particle size distribution meter. For example, by using a laser diffraction particle size distribution analyzer SALD-7000 (manufactured by Shimadzu Corporation), the particle size distribution of a slurry in which filler particles are dispersed in a solvent is measured, and the average value is calculated by calculating the average particle size (D50). You can ask.

  As the inorganic filler, it is preferable to use a surface treated with a silane coupling agent. Among these, it is preferable to use silica surface-treated with a silane coupling agent. Specifically, silica, silica (manufactured by Admatechs, average particle size), which is obtained by surface-treating silica (manufactured by Tatsumori Co., Ltd., average particle size 0.2 μm) with imidazole silane (trade name “IM-1000”, manufactured by Nikko Materials). Silica whose surface is treated with imidazole silane (trade name “IM-1000” manufactured by Nikko Materials Co., Ltd.) can be used.

The inorganic filler does not include the above “organized layered silicate”.

6. Phenoxy resin The first layer preferably contains more than 5 wt% of a phenoxy resin having a polystyrene-equivalent weight average molecular weight of 30,000 or more, more preferably 10 wt% or more, based on the total weight of the first layer. More preferably, it is contained in the range of 40-50 wt%.

By containing more than 5 wt% of phenoxy resin, it is possible to suppress the flow of the first layer resin during sealing into a through hole by pressurization such as a quick vacuum press, and an insulating layer having a uniform thickness can be formed. When phenoxy is less than 5 wt%, the first layer also flows together with the second layer during resin sealing by pressurization, and there is a problem that a uniform insulating layer thickness cannot be maintained. By forming an insulating layer having a uniform thickness, impedance matching is improved, and there is an advantage that high-frequency and high-speed signal transmission can be performed accurately. Specifically, a phenoxy resin (trade name: YX6954BH30, weight average molecular weight 39000, manufactured by Japan Epoxy Resin Co., Ltd.) can be used as the phenoxy resin.

7). Organic solvent The above components are dissolved or dispersed in an organic solvent to form a varnish, and a first layer resin composition solution and a second layer resin composition solution are respectively prepared. And it is preferable to manufacture a multilayer insulation film according to the lamination | stacking method demonstrated later. Various organic solvents can be used without particular limitation, and specifically, N, N-dimethylformamide (DMF, special grade, manufactured by Wako Pure Chemical Industries, Ltd.) can be used.

  By blending the above components, it is preferable that the first layer can form a conductor layer by chemical treatment and plating. The first layer preferably has a surface roughness Ra after chemical treatment of 200 nm or less and Rz of 2 μm or less.

(Lamination method)
Various methods can be used for laminating the multilayer insulating film. For example, a first layer resin composition solution containing the above components and a second layer resin composition solution are prepared. Next, the resin composition solution of the first layer is applied onto a base material layer such as a polyethylene terephthalate (PET) film that has been subjected to a release treatment, and is dried by heating. Further, the resin composition solution of the second layer is applied from above the first layer and dried by heating. In this way, a multilayer insulating film can be obtained. In addition, the method of laminating the film produced separately is mentioned.

(Sealing)
It is desirable to use a pressing machine as a method for sealing conductor circuits, semiconductor elements, etc. using the multilayer insulating film of the present invention. The second layer of the multilayer insulating film of the present invention can be poured into deep through vias or blind vias that cannot be sealed with a vacuum laminator. Also, as a press machine, a quick vacuum press made by Mikado Technos or a vacuum press made by Kitagawa Seiki can be used, and since it can be sealed and taken out in a short time, a quick vacuum made by Mikado Technos. It is preferable to use a press.

(Use applications)
The multilayer insulating film according to the embodiment is used for various applications, but is embedded in a gap provided in a substrate and the like, and is used for making use of the characteristics of maintaining smoothness and insulating layer thickness as an insulating layer. It is preferable to be used. For example, as an insulating layer of a build-up wiring board configured by stacking an insulating layer and a conductor circuit provided with a through hole or copper wire on a core substrate, an element such as a semiconductor chip provided on the substrate, a capacitor, an antenna circuit It can be used as a die bonding material for BGA (Ball Grid Array), CSP (Chip Size Package), and MCP (Multi Chip Package) semiconductor devices.

(Other embodiments)
As mentioned above, although this invention was described by embodiment, it should not be understood that the description and drawing which form a part of this indication limit this invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, a semiconductor device partially including the configuration described in the embodiment and a manufacturing method thereof can be manufactured in the same manner. As described above, the present invention naturally includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

[Adjustment of multilayer insulation film]
The multilayer insulating film concerning a present Example and a comparative example was prepared using the raw material shown below.

(raw materials)
1. Epoxy resin / biphenyl epoxy resin (1) (trade name “NC-3000”, epoxy equivalent 275, manufactured by Nippon Kayaku Co., Ltd.)
Biphenyl epoxy resin (2) (trade name “NC-3000H”, epoxy equivalent 288, manufactured by Nippon Kayaku Co., Ltd.)
Biphenyl type epoxy resin (3) (trade name “NC-3100”, epoxy equivalent 254, manufactured by Nippon Kayaku Co., Ltd.)
・ Bisphenol A type epoxy resin (trade name “Epicoat 828US”, epoxy equivalent 183, manufactured by Japan Epoxy Resin Co., Ltd.)
・ Bisphenol F type epoxy resin (trade name “EPICLON830S”, epoxy equivalent 168, manufactured by Dainippon Ink & Chemicals, Inc.)
2. Epoxy resin curing agent / phenolic curing agent (trade name “MEH7851-4H”, weight average molecular weight 10200 in terms of Pst, manufactured by Meiwa Kasei Co., Ltd.)
Active ester compound type curing agent (trade name “EXB-9451-65T”, weight average molecular weight 2840 in terms of Pst, manufactured by Dainippon Ink & Chemicals, Inc.)
・ Dicyandiamide (trade name “EH-3636S”, manufactured by Asahi Denka Kogyo Co., Ltd.)
3. Curing accelerator-Imidazole (Brand name "2MAOK-PW", manufactured by Shikoku Kasei Kogyo Co., Ltd.)
・ Triphenylphosphine (Wako Pure Chemical Industries, Ltd.)
4). Organized layered silicate (synthetic hectorite)
・ Synthetic hectorite chemically treated with trioctylmethylammonium salt (trade name “Lucentite STN”, manufactured by Corp Chemical)
5. Silica-silica (2) (Admatex Co., Ltd.) surface-treated with silica-silica (1) (manufactured by Tatsumori Co., Ltd., average particle size 0.2 μm) with imidazole silane (trade name “IM-1000” manufactured by Nikko Materials Co., Ltd.) Silica produced by surface treatment of imidazole silane (trade name “IM-1000” manufactured by Nikko Materials Co., Ltd.) 6. Product name: YX6954BH30, weight average molecular weight 39000, Japan Epoxy Resin Co., Ltd. Product 7. Organic solvent, N, N-dimethylformamide (DMF, special grade, manufactured by Wako Pure Chemical Industries, Ltd.)
Example 1
First layer resin composition solution: 1.00 g of synthetic hectorite “Lucentite STN” was mixed with DMF in an amount such that the final solid content ratio was 35 wt% to obtain a solution. Thereafter, the solution was stirred at room temperature until a completely uniform solution was obtained. Furthermore, the above solution in the order of 0.50 g of imidazole “2MAOK-PW”, 30.00 g of silica (1), 45.00 g of phenoxy resin, 3.40 g of biphenyl type epoxy resin (3), and 7.30 g of bisphenol A type epoxy resin. It was thrown into. At that time, each component was added to the above solution and then stirred at room temperature until a completely uniform solution was obtained, and then the next component was added to the above solution. Finally, 12.80 g of an epoxy resin curing agent “MEH7851-4H” made of a phenolic resin was added, and the resin composition solution of the first layer was prepared by stirring at room temperature until a completely uniform solution was obtained. .

  Second layer resin composition solution: 1.00 g of synthetic hectorite “Lucentite STN” was mixed with DMF in an amount such that the final solid content ratio was 60 wt% to obtain a solution. Then, it stirred at normal temperature until it became a completely uniform solution. Next, 0.10 g of imidazole “2MAOK-PW” and 0.10 g of triphenylphosphine were added to the above solution and stirred at room temperature until a completely uniform solution was obtained. Further, 50.00 g of silica (2), 3.20 g of biphenyl type epoxy resin (1), and 18.10 g of bisphenol F type epoxy resin were added to the above solution in this order.

At that time, each component was added to the above solution and then stirred at room temperature until a completely uniform solution was obtained, and then the next component was added to the above solution. Finally, 27.70 g of an epoxy resin curing agent “MEH7851-4H” made of a phenolic resin is added to the above solution and stirred at room temperature until a completely uniform solution is obtained. Prepared.

  Multilayer insulation film: The resin composition solution of the first layer is dried on a transparent polyethylene terephthalate (PET) film (trade name “PET5011 550”, thickness 50 μm, manufactured by Lintec Corporation) that has been subjected to a release treatment using an applicator. It was coated so that the subsequent thickness was 20 μm, and dried in a gear oven at 100 ° C. for 12 minutes. Furthermore, the resin composition solution of the second layer is coated on the first layer using an applicator so that the thickness after drying is 100 μm, and is dried in a gear oven at 100 ° C. for 12 minutes to obtain a multilayer insulating film Got.

(Examples 2 and 3 and Comparative Examples 1 to 5)
A resin composition solution was prepared and a multilayer insulating film was prepared in the same manner as in Example 1 except that the resin composition solutions of the first layer and the second layer were changed to the composition shown in Table 1.

[Evaluation test]
(Roughening adhesion strength evaluation)
The multilayer insulation film was heated and laminated to a glass epoxy substrate (FR-4, product number “CS-3665”, manufactured by Risho Kogyo Co., Ltd.), peeled off the PE film, and heated in a gear oven at 170 ° C. for 1 hour. The surface of one layer was subjected to the following permanganate treatment, that is, roughening treatment.

(1) Permanganate treatment A 80 ° C. potassium permanganate (Concentrate Compact CP, manufactured by Atotech Japan Co., Ltd.) roughened aqueous solution was placed in a multilayer insulating film and rocked for 15 minutes. In addition, the multi-layer insulating film after the permanganate treatment was treated for 2 minutes using a cleaning solution (Reduction Securigant P, manufactured by Atotech Japan Co., Ltd.) at 25 ° C., and then washed thoroughly and dried.

(2) Copper plating treatment Next, the roughened multilayer insulating film was subjected to copper plating treatment. The multilayer insulating film was treated with an alkaline cleaner (cleaner securigant 902) at 60 ° C. for 5 minutes to degrease and clean the surface. After washing, the multilayer insulating film was treated with a predip solution (Predip Neogant B) at 25 ° C. for 2 minutes. Thereafter, the multilayer insulating film was treated with an activator solution (activator Neogant 834) at 40 ° C. for 5 minutes to attach a palladium catalyst. Next, it was treated with a reducing solution (reducer Neogant WA) at 30 ° C. for 5 minutes. Next, the multilayer insulating film was placed in a chemical copper solution (basic print Gantt MSK-DK, copper print Gantt MSK, stabilizer print Gantt MSK), and electroless plating was performed until the plating thickness reached about 0.5 μm. After electroless plating, annealing was performed at a temperature of 120 ° C. for 30 minutes in order to remove residual hydrogen gas. In all the processes up to the electroless plating process, each process was performed while the processing liquid was 1 L on a beaker scale and the multilayer insulating film was swung. Next, electrolytic plating was performed on the electroless plated resin sheet until the plating thickness reached 20 μm. Copper sulfate (reducer Cu) was used as the electrolytic copper plating, and the current was 0.6 A / cm ² . After baking at 180 ° C. × 1 hr was performed. The obtained cured product was cut into a 10 mm width, and measured using a tensile tester (trade name “Autograph”, manufactured by Shimadzu Corporation) under the condition of a crosshead speed of 5 mm / min. The strength was measured.

(Copper adhesive strength)
A multilayer insulating film was laminated in a vacuum on a CZ-treated copper foil (CZ-8301, manufactured by MEC), and the roughening treatment with the permanganate was performed. The obtained cured product was cut into a 10 mm width, and measured using a tensile tester (trade name “Autograph”, manufactured by Shimadzu Corporation) under the condition of a crosshead speed of 5 mm / min. The strength was measured.

(Copper bond strength 2)
A multilayer insulating film is applied to CZ-treated copper foil (CZ-8301, manufactured by MEC), the press temperature of a quick vacuum press (made by Mikado Technos) is set to 90 ° C., and a SUS plate (thickness) is applied to the press plate from below. 1 mm), a multilayer insulating film (the first layer side is on top), a CZ-treated copper foil, and a SUS plate (thickness 1 mm) were stacked and set in this order, and vacuum pressing was performed at a pressure of 6 MPa for 30 minutes.

Next, it was cured at 170 ° C. for 1 hour.

The obtained cured product was cut into a 10 mm width, and measured using a tensile tester (trade name “Autograph”, manufactured by Shimadzu Corporation) under the condition of a crosshead speed of 5 mm / min. The strength was measured.

(Surface roughness (Ra, Rz) measurement)
The multilayer insulating film was pressed and pressed on a glass epoxy substrate (FR-4, product number “CS-3665”, manufactured by Risho Kogyo Co., Ltd.), and the roughening treatment with the permanganate was performed. The obtained cured product was measured for surface roughness (Ra, Rz) in a measuring range of 100 μm ² with a scanning laser microscope (product number “1LM21”, manufactured by Lasertec Corporation).

(Sealability evaluation)
A glass epoxy substrate having a thickness of 0.4 mm and a 100 mm square glass epoxy substrate (FR-4, product number “CS-3665”, manufactured by Risho Kogyo Co., Ltd.) formed with a Φ700 μm through hole with a drill was produced (through hole). Was calculated so that 95% of the volume of the second layer of the 100 mm square multi-layer insulating film would correspond to the volume of the entire through hole). Next, only the first layer was applied to PET so as to have a thickness of 20 μm with an applicator, and dried in a gear oven at 100 ° C. for 12 minutes to obtain a single-layer insulating film A. A glass epoxy substrate having through-holes formed on the single-layer insulating film A was placed, pressure-bonded at 120 ° C. and 1 MPa for 2 minutes, and further heat-bonded in a gear oven at 170 ° C. for 60 minutes to produce an evaluation substrate. Next, a 0603 capacitor chip having a die attachment film attached to the substantially central portion of the through hole was inserted and bonded onto the single-layer insulating film A, and was cured by heating at 170 ° C. for 30 minutes.

  Next, the press temperature of the quick vacuum press (manufactured by Mikado Technos) is set to 90 ° C., and the SUS plate (thickness 1 mm), the single-layer insulating film A, the evaluation substrate, and the multilayer insulating film from the bottom with respect to the press plate (The second layer was on the SUS plate side) and the SUS plate (thickness 1 mm) were stacked and set in this order, and vacuum pressing was performed at a pressure of 6 MPa for 30 minutes. The evaluation board | substrate with which the insulating film was laminated | stacked was taken out from the press, PET film was peeled, and it heat-hardened for 60 minutes in a 170 degreeC gear oven. Next, the following evaluation was performed.

(1) Embeddability Cross-sectional observation of the through-hole portion was performed with a metal microscope, and it was determined that the one sealed to the lower side was ○, and the one that was insufficiently sealed was ×. If it is not sealed, bubbles are observed.

(2) Insulating layer thickness range and variation A cross section of the through-hole portion was observed, and arbitrary continuous 50 points on the insulating layer thickness on the multilayer insulating film side were measured with a metal microscope. The insulating layer thickness range and variations were calculated based on the measurement results of the thickness difference between the center portion of the through hole and the center portion between the through holes at 50 locations.

  From the above results, it was found that the insulating film according to the example has extremely good thickness accuracy while maintaining various properties required for the insulating film. Therefore, if the insulating film according to the example is used as an insulating layer, when a circuit is formed, variations in electric resistance in the thickness direction and length of the electric signal are reduced, and signal noise and the like can be reduced.

Claims (8)

A substrate;
A first layer containing an epoxy resin, an epoxy resin curing agent, a phenoxy resin having a polystyrene-equivalent weight average molecular weight of 30,000 or more, an inorganic filler having an average particle diameter of 0.01 to 2 μm, and a curing accelerator laminated on the substrate. A first layer containing 10 wt% or more of a phenoxy resin having a polystyrene-equivalent weight average molecular weight of 30,000 or more based on the total weight of the first layer,
Layered on the first layer, an epoxy resin, an epoxy resin curing agent, an inorganic filler having an average particle size of 0.1 to 10 μm, and a second layer made of a curing accelerator,
The particle size of the inorganic filler contained in the second layer is larger than the particle size of the inorganic filler contained in the first layer,
The amount of the hardening accelerator contained in the first layer is larger than the amount of the hardening accelerator contained in the second layer.   2. The multilayer according to claim 1, wherein the first layer further includes an organic layered silicate in a ratio of 0.01 to 50 parts by weight with respect to 100 parts by weight of the total weight of the first layer. Insulating film.   The said 2nd layer further contains 0.01-50 weight part of organic layered silicate with respect to the total weight of 100 weight part of the said 2nd layer. Multilayer insulation film.   The multilayer insulating film according to claim 1, wherein the inorganic filler is silica surface-treated with a silane coupling agent. The first layer, the multilayer insulating film according to any one of claims 1 to 4, characterized in that the chemical treatment and plating can be conductive layers formed. The multilayer insulating film according to any one of claims 1 to 5, the surface roughness Ra after the chemical treatment of the first layer is 200nm or less, Rz is equal to or is 2μm or less. The multilayer insulating film according to any one of claims 1 to 6, wherein said base material which is a polyethylene terephthalate (PET) or copper foil. The polystyrene-reduced weight average molecular weight of 30,000 or more phenoxy resins, according to any one of claims 1 to 7, characterized in that it comprises in the range of 40～50Wt% based on the total weight of the first layer Multilayer insulation film.