JP5109791B2 - Insulating resin adhesive sheet and multilayer printed wiring board - Google Patents

Description

  The present invention relates to an insulating resin adhesive sheet and a multilayer printed wiring board used when manufacturing a multilayer printed wiring board.

  In recent years, due to the increasing demand for substrates used in in-vehicle devices such as various in-vehicle sensors, car navigation systems, and hybrid engine systems, organic resins have the same connection reliability as conventional ceramic substrates even in high-temperature and high-humidity environments. It is required for multi-layer printed wiring boards. For this reason, high connection reliability in a temperature cycle test, a moisture absorption reflow test, or the like has been demanded for insulating resin adhesive sheets for multilayer printed wiring boards.

  The above-mentioned problem in the temperature cycle test is that through-hole cracks due to stress caused by the difference in thermal expansion coefficient between copper and organic substrate, peeling between inner via connections, or mounting of electronic components, This is a solder crack due to stress generated due to the difference in thermal expansion coefficient with the organic substrate.

As a means for solving such a problem, a method for reducing the thermal expansion coefficient of the organic substrate by blending a large amount of an inorganic filler in the resin composition of the organic substrate and preventing the occurrence of cracks (for example, patent document) 1). However, when a large amount of the inorganic filler is blended, the circuit embedding property is insufficient due to a decrease in resin fluidity at the time of lamination, and the adhesion is deteriorated. Furthermore, the insulating resin adhesive sheet becomes brittle, and there are problems such as a significant decrease in workability due to an increase in the amount of powder fall and lack of flexibility.
Japanese Examined Patent Publication No. 2-45348

  An object of the present invention is to solve the above problems. That is, the present invention uses an insulating resin adhesive sheet for a multilayer printed wiring board that achieves high connection reliability by low thermal expansion and high workability by having flexibility, and the insulating resin adhesive sheet. An object is to provide a multilayer printed wiring board.

  In order to achieve the above object, the present inventors have conducted intensive research, and as a result, in a resin composition containing an epoxy resin, a silica fiber having a small coefficient of thermal expansion and excellent dimensional stability and chemical resistance, and flexible It discovered that the said objective can be achieved by mix | blending the specific rubber component which provides property.

That is, in the present invention, a semi-cured film made of a semi-cured resin composition is formed on a carrier film, and the resin composition comprises an epoxy resin, a curing agent, an inorganic filler, a rubber component, and silica fiber. containing, rubber component, a weight average molecular weight of 300,000 or more linear rubber component, the average fiber length of silica fiber 3 to 10 [mu] m, an average fiber diameter of 0.1 to 1.0 [mu] m, the resin composition As content in solid content, content of an epoxy resin is 2.0-15.0 mass%, content of an inorganic filler is 10-80 mass%, content of silica fiber is 0.5-5.0. The insulating resin adhesive sheet is 10% by mass to 10% by mass in the solid content of the resin composition excluding the inorganic filler .

  Further, in the present invention, the outer layer circuit and the inner layer circuit are electrically connected via the insulating resin layer, and the insulating resin layer is a state in which the insulating resin adhesive sheet of the present invention described above is singly or laminated. It is a multilayer printed wiring board formed by curing with.

  According to the present invention, an insulating resin adhesive sheet for multilayer printed wiring boards that achieves high connection reliability by low thermal expansion and high workability by having flexibility, and the insulating resin adhesive sheet are used. A multilayer printed wiring board can be provided.

(Insulating resin adhesive sheet)
The insulating resin adhesive sheet of the present invention has a carrier film and a semi-cured film made of a semi-cured resin composition formed on the carrier film. The resin composition contains an epoxy resin, a curing agent, an inorganic filler, a rubber component, and silica fiber.

Examples of the epoxy resin contained in the resin composition include bisphenol A type, bisphenol F type, biphenyl type, novolac type, polyfunctional phenol type, naphthalene type, alicyclic and alcohol type glycidyl ethers and their halides, A glycidylamine type | system | group, a glycidyl ester type | system | group, etc. are mentioned, It can use individually or in mixture of 2 or more types.
Among these, an epoxy resin having an epoxy equivalent of 250 or less and liquid at room temperature is preferable. By using the resin, the flexibility of the sheet can be improved and it is advantageous for ensuring the resin fluidity.

  The content of the epoxy resin in the solid content of the resin composition is preferably 2.0 to 15.0 mass%, and more preferably 5.0 to 10.0 mass%.

  The curing component of the epoxy resin can be divided into a curing agent and a curing accelerator. There are no particular limitations on the curing agent, and commonly used amines, acid anhydrides, phenols, and the like can be used. A phenol-based curing agent is preferable from the viewpoint of workability during semi-curing, and it is preferable to add the epoxy equivalent of the epoxy component and the hydroxyl equivalent of the phenol resin at an equivalent ratio of 1: 0.5 to 1.5. In the case of 0.5 equivalents or more, it is possible to prevent the adhesion with copper of the outer layer from being lowered. Moreover, when 1.5 equivalent or less, it can prevent that Tg and insulation fall.

  As the curing accelerator, various imidazoles are preferably used. Examples of imidazoles include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-4-phenylimidazole and the like. It is preferable that content of a hardening accelerator is 0.02-0.12 mass%, and it is more preferable that it is 0.05-0.10 mass%.

As the inorganic filler, those selected from silica, fused silica, talc, alumina, aluminum hydroxide, barium sulfate, calcium hydroxide, aerosil, calcium carbonate can be used, and these can be used alone or in combination. May be.
In view of flame retardancy and low thermal expansion, aluminum hydroxide or silica may be used alone or in combination of two or more. Moreover, it is preferable that the content shall be 10-80 mass% in solid content of a resin composition. By setting it as 10 mass% or more, it can prevent that a thermal expansion coefficient becomes large. Moreover, the fall of the circuit embedding property at the time of lamination | stacking can be prevented by setting it as 80 mass% or less.

  As the rubber component according to the present invention, a linear rubber component having a weight average molecular weight of 300,000 or more is used. With the rubber component, adhesion and moisture resistance during curing can be improved, and film properties (workability) and flexibility in a semi-cured state can be easily ensured. The content of the rubber component is preferably 10 to 60% by mass in the solid content of the resin composition excluding the inorganic filler. By being 10% by mass or more, it is possible to prevent the occurrence of a phenomenon such as a crack when peeling from the base film (carrier film) at the time of semi-curing, so that handling becomes easy. Moreover, it can prevent that the heat characteristic of hardened | cured material falls rapidly and solder heat resistance falls because it is 60 mass% or less.

Synthetic rubbers such as natural rubber, butadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, ethylene-propylene rubber, and acrylic-methacrylic rubber; Thermoplastic elastomers such as polyolefin, polyvinyl chloride and polyurethane can be used.
Among the above synthetic rubbers, epoxy-modified acrylonitrile-butadiene rubber introduced with an epoxy group is particularly preferable from the viewpoint of compatibility with the epoxy resin.
The added rubber component preferably has a viscosity of 1000 to 10000 mPa · s.
The linear rubber component refers to a rubber component in which a crosslinked structure is not formed at least when blended.

As a material of the silica fiber, quartz glass having a SiO ₂ purity of 96% or more is preferable. The average fiber length of the silica fiber is 3 to 10 μm, and the average fiber diameter is 0.1 to 1.0 μm. When silica fiber does not satisfy the above conditions, the coefficient of thermal expansion increases or the resistance to electric corrosion decreases. The average fiber length of the silica fiber is preferably 2 to 8 μm, and the average fiber diameter is preferably 0.2 to 0.9 μm.

Moreover, content of a silica fiber shall be 0.5-5.0 mass% in solid content of a resin composition. When the content is less than 0.5% by mass, the thermal expansion coefficient cannot be reduced. On the other hand, if it exceeds 5.0% by mass, the circuit embeddability decreases due to a decrease in resin fluidity, and the amount of powder falling when cutting the adhesive sheet increases.
In addition, about silica fiber, you may use the surface modification goods by a silane coupling agent etc. for the purpose of a dispersibility improvement.

  In addition to the above components, various components can be blended in the resin composition as necessary. Examples of various components include silane coupling agents and lubricants. In addition, the adhesiveness of an adhesive sheet can be improved by using a silane coupling agent.

  In order to apply the resin composition to the carrier film, it is preferable to use a coating solution in which the resin composition is dissolved and dispersed in an organic solvent. As the organic solvent, toluene, methyl ethyl ketone (MEK), dimethylformamide (DMF), dimethylacetamide (DMAC) and the like can be used. These solvents may be used alone or in a mixed system.

After the coating liquid obtained by the above blending is applied to a carrier film, the solvent is removed in the range of 80 ° C. to 180 ° C. in a drying oven and semi-cured to obtain the insulating resin adhesive sheet of the present invention.
Carrier films here include organic films that can withstand drying temperatures such as PET, PBT, PPO, and PEN, and metal foils of copper, aluminum, nickel, gold, silver, etc., which should be used alone or in combination. Can do.
“Semi-cured” means a so-called B-stage state in which the film has been slightly cured and gelled.

  The drying conditions are not particularly limited, but it is preferable that the volatile content when the insulating resin adhesive sheet is dried at 170 ° C. for 15 minutes is 2.0% or less. The volatile matter can be adjusted by adjusting the heat treatment conditions. By setting the volatile content to 2.0% or less, it is possible to prevent the tackiness of the insulating resin adhesive sheet from becoming excessive and to improve the workability.

(Multilayer printed wiring board)
In the multilayer printed wiring board of the present invention, the outer layer circuit and the inner layer circuit are electrically connected via an insulating resin layer, and the insulating resin layer alone is the insulating resin adhesive sheet of the present invention described above. Or formed by curing in a laminated state. Various methods can be applied to the production of the multilayer printed wiring board without particular limitation as long as the above configuration is adopted.

  Next, although the insulating resin adhesive sheet of this invention is demonstrated by an Example, this invention is not limited to this Example.

Example 1
・ Epoxy resin (Epicoat 828, manufactured by DIC: 70 parts by mass)
・ Curing agent (LF2882, manufactured by DIC: 40 parts by mass)
Epoxy-modified linear rubber component (HTR-708, manufactured by Nagase ChemteX: weight average molecular weight 500,000, 60 parts by mass)
・ Curing accelerator (2PZ-CNS, manufactured by Shikoku Chemicals: 0.5 parts by mass)
Silica (SC2050, manufactured by Admatex: 500 parts by mass)
Silane coupling agent (A-187, manufactured by Nihon Unicar: 5 parts by mass)
Silica fiber (average fiber length: 5.0 μm, average fiber diameter: 0.5 μm: 15 parts by mass, manufactured by Japan Vilene)

  The above components were mixed in MEK as a solvent to prepare a coating solution containing a resin composition having a solid content of 55% and a silica fiber addition amount of 2.2% by mass in the solid content of the insulating resin composition. This was coated on a release-treated PET film and dried at 130 ° C. to form a semi-cured film made of a resin composition so that the film thickness was 50 μm and the volatile content was 1.0%, and an insulating resin adhesive sheet Was made.

  On the semi-cured film of the insulating resin adhesive sheet, four insulating resin adhesive sheets from which the PET film was peeled were stacked, and heated and pressurized at 170 ° C., 3.0 MPa for 1 hour to prepare a cured resin. The thermal expansion coefficient mentioned later was calculated | required using the said resin cured material.

  Moreover, the PET film was peeled off from the produced insulating resin adhesive sheet, and this was placed on the substrate (Hitachi Kasei Kogyo MCL-E-679, 0.8t) which was etched on the entire surface. YGP-35) was mounted, and a substrate for evaluation was produced by heating and pressing at 170 ° C., 3.0 MPa for 1 hour. Using the evaluation substrate, the peel strength, solder heat resistance, electric corrosion resistance, and amount of powder fall of the sheet, which will be described later, were evaluated.

(Example 2)
An insulating resin adhesive sheet was produced in the same manner as in Example 1 except that the amount of silica fiber added was changed to 0.5% by mass of the insulating resin composition. Using the insulating resin adhesive sheet, a cured resin and a substrate for evaluation were produced in the same manner as in Example 1, and each evaluation was performed.

(Example 3)
An insulating resin adhesive sheet was produced in the same manner as in Example 1 except that the amount of silica fiber added was changed to 5.0 mass% of the insulating resin composition. Using the insulating resin adhesive sheet, a cured resin and a substrate for evaluation were produced in the same manner as in Example 1, and each evaluation was performed.

Example 4
An insulating resin adhesive sheet was prepared in the same manner as in Example 1 except that an epoxy-modified linear rubber component (SG-80H, manufactured by Nagase ChemteX: weight average molecular weight 350,000, 60 parts by mass) was used as the rubber component. did. Using the insulating resin adhesive sheet, a cured resin and a substrate for evaluation were produced in the same manner as in Example 1, and each evaluation was performed.

(Example 5)
An insulating resin adhesive sheet was prepared in the same manner as in Example 1 except that an epoxy-modified linear rubber component (HTR-280, manufactured by Nagase ChemteX: weight average molecular weight 900,000, 60 parts by mass) was used as the rubber component. did. Using the insulating resin adhesive sheet, a cured resin and a substrate for evaluation were produced in the same manner as in Example 1, and each evaluation was performed.

(Comparative Example 1)
An insulating resin adhesive sheet was produced in the same manner as in Example 1 except that no silica fiber was added. Using the insulating resin adhesive sheet, a cured resin and a substrate for evaluation were produced in the same manner as in Example 1, and each evaluation was performed.

(Comparative Example 2)
An insulating resin adhesive sheet was produced in the same manner as in Example 1 except that the silica fiber content was adjusted to 7.0 mass% of the insulating resin composition. Using the insulating resin adhesive sheet, a cured resin and a substrate for evaluation were produced in the same manner as in Example 1, and each evaluation was performed.

(Comparative Example 3)
An insulating resin sheet was produced in the same manner as in Example 1 except that the content of silica fibers having an average fiber length of 20 μm was adjusted to 2.0 mass% of the insulating resin composition. Using the insulating resin adhesive sheet, a cured resin and a substrate for evaluation were produced in the same manner as in Example 1, and each evaluation was performed.

(Comparative Example 4)
An insulating resin adhesive sheet was produced in the same manner as in Example 1 except that a crosslinked rubber component (PNR-1H, manufactured by JSR: weight average molecular weight 100,000, 60 parts by mass) was used as the rubber component. Using the insulating resin adhesive sheet, a cured resin and a substrate for evaluation were produced in the same manner as in Example 1, and each evaluation was performed.

  The following evaluation was performed about the insulation resin adhesive sheet, resin cured material, and evaluation board | substrate produced by each Example and the comparative example. The results are shown in Table 1 below.

[Thermal expansion coefficient]
About the resin cured material produced by each Example and the comparative example, the average linear expansion coefficient to 30-100 degreeC was computed in the tension mode of the thermomechanical analyzer (TMA).

[Peel strength]
A portion having a width of 10 mm and a length of 100 mm was formed on a part of the outermost copper foil. One end of the copper foil was peeled off and gripped with a gripper, and the load when peeled off at room temperature in the vertical direction by about 50 mm was measured.

[Solder heat resistance]
The evaluation substrates produced in each of the examples and comparative examples were cut into 25 mm squares, floated on a soldering iron at 288 ° C. ± 2 ° C., and the time until blistering was examined.

[Electrical corrosion resistance]
The insulating resin adhesive sheet was laminated on an insulating substrate on which an inner layer copper thickness of 12 μm was formed 30/30 μm between lines / spaces in advance, and a conductor layer was formed as the outermost layer by the method shown in Example 1. After the outermost conductor pattern is removed by etching, the test pattern is placed in a constant temperature and humidity chamber adjusted to 85 ° C. and 85% RH, and a voltage of DC 5.0 V is continuously applied to deteriorate the insulation pattern of the inner layer comb pattern. The time until occurrence of was measured.

[Amount of powder fallen from sheet]
The presence or absence of occurrence of powder falling during the cutting process at room temperature of the insulating resin adhesive sheet in the B stage state was evaluated.

  From Table 1, the resin cured product and the evaluation substrate using the adhesive sheet of the present invention are multilayer printed wiring such as adhesive strength with plated copper, 288 ° C. solder heat resistance, and electric corrosion resistance as shown in Examples 1 to 5. It was confirmed that a low coefficient of thermal expansion was exhibited while satisfying various properties as a plate application.

  On the other hand, in the comparative example 1 which does not contain a silica filler essential, the thermal expansion coefficient increased compared with the Example. In addition, when the silica fiber was excessively added (Comparative Example 2) and when the crosslinked rubber component was used (Comparative Example 4), the amount of powder falling off of the insulating resin adhesive sheet became remarkable. In the case of the comparative example 3 whose average fiber length is 20 micrometers, the electrolytic corrosion resistance between 30 micrometers fine wire comb type | mold patterns fell.

Claims (2)

A semi-cured film made of a semi-cured resin composition is formed on the carrier film,
The resin composition contains an epoxy resin, a curing agent, an inorganic filler, a rubber component, and silica fiber,
The rubber component is a linear rubber component having a weight average molecular weight of 300,000 or more,
The average fiber length of the silica fiber is 3 to 10 μm, the average fiber diameter is 0.1 to 1.0 μm,
As content in solid content of the said resin composition, content of an epoxy resin is 2.0-15.0 mass%, content of an inorganic filler is 10-80 mass%, and content of silica fiber is 0. 5 to 5.0% by mass , and an insulating resin adhesive sheet in which the content of the rubber component is 10 to 60% by mass in the solid content of the resin composition excluding the inorganic filler . The outer layer circuit and the inner layer circuit are electrically connected via an insulating resin layer,
A multilayer printed wiring board in which the insulating resin layer is formed by curing the insulating resin adhesive sheet according to claim 1 alone or in a laminated state.