Laminate and multilayer printed wiring board

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a laminated board and a multilayer printed wiring board.

【0002】

[Conventional technology]

When manufacturing a multi-layer printed wiring board, one or more prepreg sheets made of epoxy resin-impregnated glass cloth base material are laminated on the inner layer circuit board on which the circuit is formed, and copper foil is further laminated on the prepreg sheet and applied by a hot plate press. It has undergone a process of pressure integral molding. When the outer layer copper foil of the obtained multilayer printed wiring board is removed and a conductor is formed on the surface by plating, a part of the glass cloth used for the prepreg sheet is exposed by pretreatment or the like, and the conductor is formed. At the time of this, the adhesion of the plated metal was insufficient in this exposed portion. Further, even if the conductor can be formed, a problem such as a short circuit may occur between the outer layer patterns finally formed due to the penetration of the plating liquid from the interface of the exposed glass cloth.

【0003】

[Problems to be Solved by the Invention]

An object of the present invention is to provide a laminated board and a multilayer printed wiring board having excellent chemical resistance and toughness.

【0004】

[Means for solving problems]

Such an object can be achieved by the present invention described in the following (1) to (9). (1) A laminated board having a core material having an inner layer circuit and an insulating layer, and the insulating layer has a first layer composed of a base material and a resin and a second layer composed of a resin. Laminated board characterized by. (2) The laminate according to (1) above, wherein the first layer and the second layer are laminated at least once in the order of a core material having an inner layer circuit, a first layer, and a second layer. .. (3) The laminated board according to (1) or (2) above, wherein the resin constituting the second layer contains a thermosetting resin. (4) The laminated board according to any one of (1) to (3) above, wherein the resin constituting the second layer contains a thermoplastic resin and a thermosetting resin. (5) The laminate according to (4) above, wherein the thermoplastic resin is at least one selected from the group of phenoxy resin, polyether sulfone resin, and polysulfone resin. (6) The laminate according to (3) or (4) above, wherein the thermosetting resin is at least one selected from bisphenol A type epoxy resin, bisphenol F type epoxy resin, and novolak type epoxy resin. (7) The laminate according to (3) or (4) above, wherein the resin constituting the second layer contains an epoxy resin or phenoxy resin having a weight average molecular weight of 10,000 or more and an epoxy resin having an epoxy equivalent of 1000 or less. (8) The laminated board according to any one of (1) to (7) above, wherein the thickness of the second layer is 1 to 100 μm. (9) A multilayer printed wiring board characterized in that a metal foil is bonded to at least one surface of the laminated board according to any one of (1) to (8) above.

【0005】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the laminated board and the multilayer printed wiring board of the present invention will be described in detail. The laminated board of the present invention is a laminated board having a core material having an inner layer circuit and an insulating layer, and the insulating layer is a first layer composed of a base material and a resin and a second layer composed of a resin. And have. Further, the multilayer printed wiring board of the present invention is formed by joining a metal foil to at least one surface of the laminated board.

【0006】

Hereinafter, the laminated board of the present invention will be described. The laminated board of the present invention has an insulating layer having a first layer composed of a base material and a resin and a second layer composed of a resin. Thereby, toughness and chemical resistance can be improved. When the chemical resistance is improved, the resistance to chemicals used in the plating process is improved, and a conductor can be formed by plating on the surface layer of the second layer. Examples of the base material constituting the first layer include glass fiber base materials such as glass woven cloth and glass non-woven fabric, and organic fiber base materials such as aramid fiber and paper. Among these, a glass fiber base material is preferable. Thereby, the toughness of the laminated board or the like can be further improved.

【0007】

Examples of the resin constituting the first layer include a novolak type epoxy resin, an epoxy resin such as a bisphenol type epoxy resin, and a thermosetting resin such as a phenol resin. Of these, epoxy resin is preferable. As a result, electrical characteristics (particularly insulation) and withstand voltage can be improved. Among the epoxy resins, bisphenol type epoxy resins are preferable. Thereby, the flexibility of the laminated board can be improved. In addition, the interfacial adhesion with the inner conductor layer and the second layer can be improved. The thickness of the first layer is not particularly limited, but is preferably 10 to 400 μm, particularly preferably 20 to 150 μm. If the thickness is less than the lower limit, the impregnation property of the resin into the base material may decrease. Further, if the upper limit value is exceeded, it may be difficult to create a non-through hole by a laser.

【0008】

In the present invention, the second layer is made of a resin. Composed of resin means that it does not contain a base material. Therefore, the resin can also contain an inorganic filler. The resin constituting the second layer preferably contains a thermosetting resin. Thereby, the chemical resistance can be further improved. Examples of the thermosetting resin include epoxy resin, phenol resin, polyimide resin and the like. Among these, at least one resin selected from the group consisting of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and novolak type epoxy resin is preferable. Thereby, the electrical characteristics can be particularly improved. It can also be cheaper.

【0009】

The resin constituting the second layer is not particularly limited, but preferably contains a thermoplastic resin and a thermosetting resin. Thereby, plasticity can be imparted. In addition, it is possible to prevent the laminated board from falling off. If the powder falling property can be prevented, the resin does not adhere to the surface conductor layer during press molding, and the yield at the time of forming the surface circuit is improved. The same thermosetting resin as described above can be used. Examples of the thermoplastic resin include phenoxy resin, polyethersulfone resin, polysulfone resin and the like. Further, the thermoplastic resin and the thermosetting resin are preferably used in combination at a weight ratio of 3: 7 to 9: 1, and particularly preferably 5: 5 to 8: 2. As a result, both chemical resistance and plasticity can be achieved.

【0010】

The resin constituting the second layer is not particularly limited, but an epoxy resin or phenoxy resin (a) having a weight average molecular weight of 10,000 or more and an epoxy resin (b) having an epoxy equivalent of 1000 or less may be used in combination. preferable. The epoxy resin or phenoxy resin (a) having a weight average molecular weight of 10,000 or more reduces the resin flow during molding, maintains the thickness of the insulating layer, and imparts flexibility to the composition. The epoxy resin (b) having an epoxy equivalent of 1000 or less is preferably blended in order to improve the drawbacks of the epoxy resin or phenoxy resin (a), such as high flexibility, high viscosity, and poor workability. Is to be done. The epoxy resin (b) used is not particularly limited, but it is preferable that the softening point of the mixed resin composition is in the range of 60 to 90 ° C. Specifically, when applying to a copper foil or a carrier film, it is appropriate to use an epoxy equivalent of about 200 to 450 in consideration of workability and the like. However, if a large amount of epoxy resin that is liquid at room temperature is blended, stickiness may remain after drying and stains of the liquid epoxy resin may occur from the insulating resin layer. Therefore, the amount of the liquid epoxy resin blended is usually 10 to 40% by weight. preferable. The thickness of the second layer is not particularly limited, but is preferably 1 to 100 μm, and particularly preferably 5 to 80 μm. If the thickness is less than the lower limit, it may be difficult to form a film, and if it exceeds the upper limit, the bending elasticity and toughness of the laminated board may decrease. Inorganic fillers such as fused silica, silica such as crystalline silica, alumina, aluminum hydroxide, barium sulfate, calcium carbonate, talc, clay, etc. are added to the resins of the first layer and the second layer. Is preferable. As a result, the solder heat resistance at 288 ° C can be improved. Further, the inorganic filler is preferably added in an amount of 3 to 900 parts by weight, particularly preferably 5 to 100 parts by weight, based on 100 parts by weight of the resin. If the inorganic filler is within the above range, the solder heat resistance at 288 ° C can be improved.

【0011】

The first layer and the second layer are not particularly limited, but it is preferable that the core material having the inner layer circuit, the first layer, and the second layer are laminated at least once in this order. This makes it possible to perform additive plating. When additive plating becomes possible, the conductor layer can be made thinner and a fine pattern can be formed. Further, since the unevenness of the surface due to the base material can be reduced, it becomes possible to further draw a fine pattern. Further, the wiring density can be improved by repeating the configuration of the core material having the inner layer circuit, the first layer, and the second layer to manufacture the laminated board. As a result, the area of the multilayer printed wiring board can be reduced. The core material having an inner layer circuit is a sheet obtained by impregnating a reinforcing base material such as a paper base material, a glass base material, or a synthetic resin fiber base material with a resin such as epoxy, phenol, polyimide, BT, polyester, or tetrafluoroethylene. Examples include copper-clad laminates in which (prepregs) are laminated, heat-pressurized, laminated and integrated, holes are made at necessary locations, and the inner walls of the holes are metallized and connected.

【0012】

Next, the multilayer printed wiring board will be described. Normally, an insulating layer (prepreg) between a core material having a plurality of inner layer circuits and a core material having the inner layer circuits is laminated together, heated and pressurized to be laminated and integrated, holes are made at necessary places, and the inner wall of the holes is formed. Circuit formation and insulation layer formation by forming an insulating layer on a multi-layer printed wiring board that is metallized and connected and a core material that has an inner layer circuit, making holes at necessary points, and metalizing and connecting the inner walls of the holes. There is a multi-layer printed wiring board that sequentially performs. The multilayer printed wiring board of the present invention has a metal foil bonded to at least one surface of the above-mentioned laminated board. An example of the multilayer printed wiring board of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, the multilayer printed wiring board of the present invention includes a core material 1 having an inner layer circuit, a first layer 2 composed of a base material and a resin, a second layer 3 composed of a resin, and a metal. It is composed of foil 4. As the metal foil 4, a metal foil 4 in which the second layer 3 is previously formed on the surface thereof, for example, by coating or the like can be used. In this case, the core material 1 having the inner layer circuit and the first layer 2 may be laminated in advance, and then the metal foil 4 having the insulating layer of the second layer may be joined.

【0013】

[Example]

Hereinafter, the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

【0014】

(Example 1) Insulation layer of the first layer Preparation of resin varnish 80 parts by weight of bisphenol A type epoxy resin (epoxy equivalent 480, softening point 65 ° C) was dissolved in 80 parts by weight of ethyl carbitol (boiling point 202 ° C). To this, 20 parts by weight of orthocresol novolac type epoxy resin (epoxy equivalent 215, softening point 70 ° C) was dissolved in 20 parts of methyl ethyl ketone (MEK) and mixed, and 4.4 parts by weight of dicyandiamide was added and dissolved as a curing agent. Further, 0.1 part by weight of 2-phenyl-4-methylimidazole was added as a curing accelerator, and the mixture was mixed in the compounding layer. Further, the viscosity was adjusted by MEK to obtain an epoxy resin varnish for impregnation. Impregnation of substrate 100 parts by weight of glass cloth base material (thickness 0.1 mm, manufactured by Nitto Boseki Co., Ltd.) is impregnated with 80 parts by weight of varnish solid content, dried in a dryer at 150 ° C for 5 minutes, and the resin impregnation amount is 44.4%. The first insulating layer of the above was prepared.

【0015】

Insulation layer of the second layer Preparation of resin varnish 100 parts of brominated epoxy resin (epoxy equivalent 6400, weight average molecular weight 30000) and 50 parts of bisphenol F type epoxy resin (epoxy equivalent 175, Epicron 830 manufactured by Dainippon Ink and Chemicals Co., Ltd.), bisphenol A type epoxy resin with epoxy equivalent 450 (Epoxy equivalent 450, Epicoat 1001 manufactured by Yuka Shell Co., Ltd.) was dissolved in MEK, and 5 parts of 2-methylimidazole as a curing agent and titanate-based coupling agent (KR-46B manufactured by Ajinomoto Co., Ltd.) were dissolved therein. ) 0.3 part and 30 parts of calcium carbonate were added to prepare a resin varnish. Application to metal leaf The above-mentioned resin varnish of the second layer was applied to the anchor surface of a copper foil having a thickness of 18 μm with a comma coater so as to have a dry resin thickness of 40 μm to obtain a copper foil with an insulating resin.

【0016】

Core material layer The core material having the inner layer circuit was obtained by patterning a glass epoxy double-sided copper-clad laminate (ELC4765) having a base material thickness of 0.4 mm and a copper foil thickness of 18 μm.

【0017】

Manufacture of multi-layer printed wiring boards After the core material having the above-mentioned inner layer circuit was blackened, the insulating layer of the first layer was set on both sides of the core material one by one, and the copper foil with the insulating resin was further set on both sides. Place the set product with a 1.6 mm stainless steel mirror plate between the products, insert 15 sets in one stage, and perform a vacuum press under the conditions of temperature rise 3 ° C / min, pressure 30 kgf / cm2, and vacuum degree -740 mmHg. A multi-layer printed wiring board was produced by heat molding at a product temperature of 160 ° C for 45 minutes or more.

【0018】

Circuit formation A through hole of 0.3 mmφ was formed in the above-mentioned multilayer printed wiring board by a mechanical drill. In addition, the outer layer copper foil was etched and carbon dioxide laser irradiation was performed to provide non-through holes. Next, desmear roughening (permanganate treatment 10 minutes), pretreatment for treatment plating, electroless plating, and further electrolytic plating formed a copper layer (25 μm) in the non-through holes and the etched portion. After that, a circuit with L / S = 100/150 μm was formed.

【0019】

(Example 2) In the insulating layer of the first layer, except that a novolac type epoxy resin (Epicron 152 epoxy equivalent 175 manufactured by Dainippon Ink Co., Ltd.) was used instead of the bisphenol A type epoxy resin, the same as in Example 1. I did the same.

【0020】

(Example 3) In the insulating layer of the second layer, a phenoxy resin (DER684EK40 manufactured by Dow Chemical Co., Ltd., weight average molecular weight 30000) was used instead of the brominated epoxy resin, but the same procedure as in Example 1 was carried out.

【0021】

(Example 4) The same as in Example 1 was carried out except that the bisphenol A type epoxy resin was not used in the insulating layer of the second layer.

【0022】

(Comparative Example 1) The same procedure as in Example 1 was carried out except that the copper foil did not have the insulating layer of the second layer.

【0023】

(Comparative Example 2) The same as in Example 1 except that the prepreg of the first layer was not provided.

【0024】

The results obtained by the above-mentioned Examples and Comparative Examples are shown in Table 1. Each evaluation was performed by the following method. Plating The plating property was evaluated by the appearance after plating. indicates that there is no abnormality, and × indicates that there is a non-attached part. Plating peel strength The plating peel strength was measured according to JIS C6481. Insulation between outer layers For the insulation between the outer layers, the insulation resistance value was evaluated after a steady humidification test of 85 ° C and 85% RH 1000 hours at a applied voltage of 50 V. indicates that there is no abnormality, and × indicates that there is a short circuit. Bending strength Bending strength was measured according to JIS C 6481. Solder heat resistance The solder heat resistance was evaluated according to JIS C6481. The processing conditions were in accordance with S-260 ° C20.

【0025】

[table 1]

<img file="JP2003124635A_D0001.tif" />【0026】

As shown in the table, the multilayer printed wiring boards obtained in Examples 1 to 4 were excellent in plating resistance (chemical resistance) and bending strength (toughness). Further, particularly in the case of Example 1, the plating peel strength and the solder heat resistance were excellent.

【0027】

[Effect of the invention]

The laminated board and the multilayer printed wiring board of the present invention are excellent in chemical resistance and toughness. Further, when a specific resin is used for the insulating layer of the second layer, the plating peel strength and the solder heat resistance are excellent. If the plating peel strength is excellent, additive plating becomes possible, and fine patterning becomes possible.

[Simple explanation of drawings]

[Figure 1]

It is a side view which shows typically an example of the multilayer printed wiring board of this invention.

[Explanation of symbols]

1 core material 2 1st layer 3 2nd layer 4 metal leaf