JPH11148053A - Heat-resistant plastic film laminate and multilayer printed circuit using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the heat-resistant plastic film laminate that reduces its surface roughness to inhibit the formation of the outer layer circuit due to the roughness of the inner layer circuit, when the outer layer circuit is formed via the adhesive layer on the inner layer circuit. SOLUTION: In a laminated body in which an adhesive layer is formed on one face of the heat-resistance plastic film, the resin flow of the adhesive layer is set to 3.0-5.0%. In a preferred embodiment, this heat-resistant plastic film laminated body is produced by coating the heat-resistant film with an adhesive layer on the one face and with copper foil on the other face. The objective multi-layered printed circuit board uses this heat-resistant plastic film laminated body as the outer layer material for the inner board.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a heat-resistant plastic film laminate suitable for an outer layer material of a multilayer printed wiring board and a multilayer printed wiring board using the same.

[0002]

2. Description of the Related Art A multilayer printed wiring board is a printed wiring board having a conductor pattern in three or more layers including a surface conductor layer. A multilayer printed wiring board is formed by laminating an inner layer material and an outer layer material on which a circuit is formed on a double-sided copper-clad laminate by etching or other methods, and bonding and integrating the circuit on the outer layer material surface of the multilayer printed wiring board laminate. Obtained. As the outer layer material, a single-sided copper-clad laminate or a copper foil is used. An epoxy resin prepreg based on glass cloth is used for bonding between the inner layer materials and between the inner layer material and the outer layer material. In recent years, with the demand for miniaturization and weight reduction of electronic devices, multilayer printed wiring boards have also been required to be thin, and the thickness of the insulating layer has been reduced to 30%.
Wiring boards of １００100 μm have also appeared. It has also been proposed to use an adhesive film that does not contain glass cloth for the insulating layer used for this purpose in order to make the insulating layer thin.

[0003] Recent multilayer printed wiring boards have a high-density wiring, and the number of locations used for electrical connection between one conductive layer and another conductive layer is increasing. For this reason, through-holes are provided through the wiring board, and copper plating is deposited on the inner walls of the through-holes to electrically connect the different conductor layers. Holes must pass through layers other than the layer to be formed, and wiring must be performed in layers irrelevant to connection, avoiding the holes, which hinders the degree of freedom of design and the increase in wiring density. Therefore, a so-called interstitial via hole (I) is used to connect only a wiring layer that requires connection, instead of using only a hole penetrating the entire wiring board.
VH).

As a method of forming an IVH, an insulating resin is applied by screen printing or a curtain coater, and the like.
Laser drilling method (laser processing method),
A method of forming a hole by exposure and development using a photosensitive resin as an insulating resin (photo method), a method of forming a hole by dissolving the insulating resin by chemical treatment (chemical etch method), and the like have been proposed. There is also a method in which an insulating resin is previously used as a film to form an insulating layer with a vacuum laminator or the like.

[0005]

The method of applying an insulating resin by screen printing, a curtain coater or the like, and the method of forming an insulating layer by a vacuum laminator or the like have a problem that unevenness of an inner layer circuit appears on the surface. These irregularities cause problems in the formation of fine patterns, such as impairing the adhesion of the etching resist and reducing the plating throwing power when circuit processing the outer layer material. It is an object of the present invention to provide a laminate in which the unevenness of the inner layer circuit does not appear on the surface.

[0006]

Means for Solving the Problems The present inventors have conducted various studies on means for solving the above-mentioned problems, and as a result, have reached the present invention. The present invention is a heat-resistant plastic film laminate in which an adhesive layer is formed on one surface of a heat-resistant plastic film, and the resin flow of the adhesive layer is 3.0 to 5.0%. Further, it is preferable that the adhesive layer is formed on one side of the heat-resistant plastic film and a copper foil is formed on the other side of the heat-resistant plastic film. . Further, the present invention is a multilayer printed wiring board using the heat-resistant plastic film laminate as an outer layer material. Then, after laminating the heat-resistant plastic film laminate, a via hole is preferably provided by using a laser to provide a multilayer printed wiring board. We have:
Heat-resistant plastic film and resin flow between 3.0 and 5.
It has been found that a laminate having no unevenness of the inner layer circuit on the surface can be obtained by combining the adhesive layer of 0%.

According to the present invention, there is provided a laminate comprising a heat-resistant plastic film having an adhesive layer formed on one side as described above, wherein the resin flow of the adhesive layer is 3.0 to 5.0%. This heat-resistant plastic film laminate is laminated and integrated with an inner layer material on which a circuit has been formed to form a multilayer printed wiring board.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The adhesive layer constituting the laminate has a resin flow of 3.0 to 5.0.
%. If the resin flow is less than 3.0%, the ability to follow irregularities on the surface of the inner layer material during lamination is poor, and voids are likely to occur. Formability such as a decrease in plate thickness is a problem. The resin flow controls the curing reaction of the adhesive,
It can be controlled by the composition of the adhesive. That is, an adhesive layer of a necessary resin flow can be obtained by appropriately setting the molecular weight of the adhesive component, the type of the curing accelerator or the curing agent, the compounding amount, or the application conditions. Here, the resin flow of the adhesive layer is defined as a double-sided copper-clad film of 100 mm in both length and width (the outer side of a double-sided copper-clad film in which copper foil is stuck on both sides via an adhesive cured to the B stage). Is heated and pressurized with a hydraulic press at a temperature of 170 ° C. and a pressure of 14.7 MPa for 10 minutes, and then the vertical and horizontal lengths are measured at 10 points each. When the average of the measured values of the width is a and the average of the measured values of the horizontal length is b, it is a value obtained by the following equation 1.

[0009]

## EQU1 ## Flow of resin in adhesive layer (%) = (a × b / 10)
0) -100

[0010] The adhesive layer constituting the laminate is required to have the ability to follow irregularities on the surface of the inner layer material during lamination, the adhesion to the inner layer material, and the heat resistance required as a wiring board after lamination. Therefore, for the adhesive layer, it is preferable to use a thermosetting resin such as an epoxy resin, a polyimide resin, a cyanate resin, a phenol resin, and a melamine resin, and particularly an adhesive mainly composed of an epoxy resin from the viewpoint of handleability.

Further, in order to improve the handleability during the laminating operation, a polymer having a film forming ability is blended in addition to the adhesive main component. As the polymer having a film-forming ability, it is preferable to use a high-molecular-weight epoxy polymer having a film-forming ability, particularly a high-molecular-weight epoxy polymer having a weight average molecular weight of 100,000 or more. As the polymer having film forming ability, it is also possible to mix a high molecular weight epoxy polymer having film forming ability and a film forming polymer which is compatible with the high molecular weight epoxy polymer and is soluble in the same solvent. is there. Here, the film-forming ability means that troubles such as cracking or missing of the resin occur during the steps of transporting, cutting and laminating the film. The fact that the epoxy resin is the main component of the adhesive means that the epoxy resin composition containing the epoxy resin and its curing agent and curing accelerator is larger than other adhesive resin components.

In the present invention, the heat-resistant plastic film refers to a plastic film having a high melting point and a high glass transition temperature. It is a thermoplastic resin having a glass transition temperature of 90 ° C. or higher for amorphous plastic and a plastic having a melting point of 200 ° C. or higher for crystalline plastic. Also, for example, polyimide having no clear glass transition temperature or melting point is included. As plastics meeting such conditions, polyesters having an aromatic ring or a heterocyclic ring in the main chain, polyethylene naphthalate, polyarylate, polyether sulfone, polyether ether ketone,
Examples thereof include polyetherimide, polysulfone, polyphenylene sulfide, polyphenylene ether, polyamide having an aromatic ring or a heterocyclic ring in the main chain, aramid, polyimide, fluororesin, polycarbonate, liquid crystal polymer, and the like.

The heat-resistant plastic film laminate of the present invention can be formed by forming an adhesive layer on one side of the heat-resistant plastic film by means such as coating or by integrating the adhesive in a film form by pressing or the like. To manufacture.
In addition, a copper foil is laminated on one side of a heat-resistant plastic film, and then an adhesive layer is formed on the other side by means of coating or the like, or the adhesive is formed into a film in advance and integrated by pressing or the like. Is a preferred production method.
As a method of laminating a copper foil on one side of a heat-resistant plastic film, a method of laminating a copper foil while extruding a plastic into a film with an extruder, a method of laminating a copper foil on one side of a heat-resistant plastic film and heat-melting and bonding the same A method of casting a heat-resistant plastic on a copper foil can be used. Of course, it may be obtained by another appropriate method.

The heat-resistant plastic film laminate is laminated and integrated with an inner layer material on which a circuit has been formed to form a multilayer printed wiring board. After laminating the heat-resistant plastic film laminate on the circuit-formed inner layer plate, it is preferable to use a laser when providing a via hole. The circuit of the outer layer is formed by plating after forming a via hole by laser. If a heat-resistant plastic film laminate in which an adhesive layer is formed on one side of a heat-resistant plastic film and a copper foil is formed on the other side in advance, the copper foil can be used as a conductor. Further, after removing the copper foil, a circuit can be formed by plating or the like.

It is desirable to use an epoxy resin as an adhesive main component of the adhesive layer. The epoxy resin is not limited as long as it is a compound having two or more epoxy groups in a molecule. For example, phenol such as phenol novolak type epoxy resin, cresol novolak type epoxy resin, resol type epoxy resin, and bisphenol type epoxy resin Glycidyl ethers such as epoxy resins (phenolic epoxy resins), alicyclic epoxy resins, epoxidized polybutadienes, glycidyl ester epoxy resins, glycidylamine epoxy resins, and isocyanurate epoxy resins. Epoxy resins imparted with flexibility can also be used. These epoxy resins may be used alone or in combination of two or more. A phenolic epoxy resin or a mixture of a phenolic epoxy resin and a polyfunctional epoxy resin is preferable in order to have solder heat resistance and peel strength required for a printed wiring board.

A curing agent and a curing accelerator are used for the epoxy resin. As the curing agent and the curing accelerator for the epoxy resin, novolak type phenol resin, dicyandiamide, acid anhydride, amines, imidazole, phosphine and the like are used. These can be used alone or in combination.

In order to improve the ease of handling during laminating work, it is preferable to blend a polymer having a film forming ability in addition to the adhesive main component. Coalescing is preferred. When only the high molecular weight epoxy polymer is used, the weight average molecular weight of the high molecular weight epoxy polymer is 100,00.
It must be 0 or more and soluble in a solvent. If the high-molecular-weight epoxy polymer is not soluble in the solvent, an adhesive varnish cannot be obtained. Can not do it.

When the weight average molecular weight of the high molecular weight epoxy polymer is less than 100,000, the strength at ordinary temperature, the storage modulus is easily lowered, or the storage modulus is lowered at the molding stage, so that good handleability or good handling property is obtained. It is difficult to obtain a multi-layer printed wiring board with a pre-drilling type IVH. Therefore, when a high-molecular-weight epoxy polymer having a weight-average molecular weight of less than 100,000 is used as a film-forming component of the insulating adhesive film serving as the adhesive layer, the high-molecular-weight epoxy polymer has compatibility with the high-molecular-weight epoxy polymer and has high Acrylic rubber, nitrile rubber, butyral resin, polyvinyl alcohol, polyurethane, polyamide, polyester, polyether resin, polyolefin, or a modified product thereof, which is soluble in a common solvent with a molecular weight epoxy polymer and has film forming properties. It is necessary to use them together in order to obtain a good insulating adhesive film and a multilayer printed wiring board with a predrilling method IVH.

The high-molecular-weight epoxy polymer is a bifunctional epoxy resin and a difunctional phenol, and the equivalent ratio of the difunctional epoxy resin to the difunctional phenol is epoxy group / phenol hydroxyl group = 1/0. The concentration of the reaction solids in an amide-based or ketone-based solvent having a boiling point of 130 ° C. or more using an alkali metal compound, an alkaline earth metal compound, an imidazole, an organic phosphorus compound, an amine, or the like as a catalyst. It can be obtained by heating and polymerizing at 50% by weight or less (JP-A-4-120122, JP-A-4-120122).
-120123, JP-A-4-120124, JP-A-4-120125, JP-A-41227
No. 14, JP-A-4-122713).

Further, the heat resistance and the heat resistance of the multilayer printed wiring board can be improved by appropriately making the high molecular weight epoxy polymer, which is a film-forming main component of the insulating adhesive film serving as the adhesive layer, three-dimensional using a crosslinking agent. It is effective as a method for improving solvent properties, water absorption and insulation reliability. Examples of the crosslinking agent include a block type polyisocyanate in which an isocyanate group is blocked using a polyisocyanate and a compound having active hydrogen as a masking agent, an epoxy resin, a silanol compound, a metal oxide, and an acid anhydride.

Among them, a block type polyisocyanate which can easily control the reactivity of the crosslinking agent, easily secure the storage stability of the adhesive varnish, and can be expected not to cause deterioration of the properties of the insulating adhesive film and the multilayer printed wiring board. It is desirable to use. As a block type polyisocyanate,
Tolylene diisocyanate (TDI) blocked with phenolic, oxime-based, alcohol-based masking agents, etc.
Examples include isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), and hexamethylene diisocyanate (HDI). To improve the heat resistance of the multilayer printed wiring board, TDI blocked with a phenol novolak-based masking agent is preferable, but these masking agents and isocyanates may be used in combination.

In order to make the laminate flame retardant, it is preferred to use a halogenated, especially brominated, high molecular weight epoxy polymer or to incorporate a reactive flame retardant. Known as an additive-type flame retardant for flame retarding, it is conceivable to incorporate a phosphorus-based flame retardant, a nitrogen-based flame retardant, and an inorganic-based flame retardant. Due to poor characteristics, it is desirable to incorporate a reactive flame retardant. Reactive flame retardants include halogenated epoxy resins,
Preferably, the brominated epoxy resin or the like is optimal in consideration of the high flame retardant effect, the uniformity of the adhesive layer, and the characteristics of the multilayer printed wiring board. Polyfunctional halogenated phenols, particularly polyfunctional brominated phenols, are preferred because they act as curing agents for epoxy resins and provide good multilayer printed wiring board properties. In any case, the halogen content is preferably from 10 to 40% by weight,
More preferably, it is ２５25% by weight.

It is preferable to further add a silane coupling agent to the adhesive to be the adhesive layer in order to improve the adhesive strength between the adhesive and the circuit conductor of the inner layer material. As the silane coupling agent to be added, epoxy silane, amino silane, urea silane and the like are preferable.

The heat-resistant plastic film laminate of the present invention is overlaid with an inner layer material on which a circuit has been formed, and heated and pressed to form a multilayer printed wiring board. When heating and pressurizing, the cushioning material to be placed between the end plate and the cushioning material is preferably a cushioning material having a property of flowing at a molding temperature. Examples of such a cushioning material include a polyethylene sheet and a polyvinyl chloride sheet having a thickness of 40 to 100 μm. Further, it is preferable to use this cushion material in combination with another cushion material and a release sheet.

[0025]

The present invention will be described below in detail with reference to examples. Example 1 100 parts by weight of a brominated high molecular weight epoxy polymer having a weight average molecular weight of 300,000, 20 parts by weight of tolylene diisocyanate (TDI) blocked with phenol novolak acting as a crosslinking agent, bisphenol A Type epoxy resin (epoxy equivalent = 172) 2
5 parts by weight of phenol novolak, which acts as a curing agent, is mixed with an epoxy resin in an equivalent amount, and 0.5 parts by weight of a urea silane coupling agent is added. A varnish for a film was obtained.

The varnish was applied to one surface of a polyimide film (MCF-5000I, trade name of Hitachi Chemical Co., Ltd.) having a thickness of 25 μm, which had been subjected to a mat treatment on both sides in advance, and
It was dried and semi-cured at 00 ° C. for 1 minute and at 130 ° C. for 1 minute to obtain a polyimide film laminate having an adhesive layer thickness of 50 μm and a bromine content of 25% by weight. The resin flow in the adhesive layer was 3.0%. Separately, a wiring pattern was formed on both sides of a glass cloth base epoxy resin copper-clad laminate (copper foil thickness 35 μm) to obtain an inner circuit board. A laminate of polyimide films was formed on both surfaces of the inner circuit board by heating and pressing to form a laminate. An IVH having a diameter of 0.1 mm is opened by a carbon dioxide gas laser at a position where the conductor land portion of the inner layer circuit board of the laminate is located, the laminate is subjected to electroless copper plating and electrolytic copper plating by a conventional method, and outer layer wiring is processed. To obtain a four-layer printed wiring board.

(Example 2) The weight average molecular weight was 300,0
Example 1 except that instead of 100 parts by weight of the 00 brominated high molecular weight epoxy polymer, 60 parts by weight of the brominated high molecular weight epoxy polymer having a weight average molecular weight of 50,000 and 40 parts by weight of the modified acrylic rubber were blended. In the same manner as in the above, a four-layer printed wiring board with an IVH was obtained. The resin flow in the adhesive layer was 5.0%.

Example 3 Instead of a polyimide film (MCF-5000I, trade name of Hitachi Chemical Co., Ltd.) having a resin layer thickness of 25 μm, a copper foil thickness of 18 μm and a thickness of 2
IVH in the same manner as in Example 1 except that a polyimide film of 5 μm (one-side matte-treated with copper foil) was used.
To obtain a four-layer printed wiring board. The resin flow of the adhesive layer was 3.5%.

(Example 4) A polyimide film with copper on one side having a copper foil thickness of 12 μm and a resin thickness of 10 μm was used, the thickness of the adhesive layer was 25 μm, and the thickness of the copper foil of the inner circuit board was 18 μm. Other than the above, I was the same as in Example 1.
A four-layer printed wiring board with VH was obtained. The resin flow in the adhesive layer was 4.0%.

Example 5 Instead of a polyimide film, a 30 μm thick polyethersulfone film (VI
CTREX; trade name, manufactured by Sumitomo Chemical Co., Ltd.)
Otherwise in the same manner as in Example 1, a four-layer printed wiring board with IVH was obtained. The resin flow in the adhesive layer was 3.0%.

Example 6 A four-layer printed wiring with IVH was used in the same manner as in Example 1 except that a polyetherimide film having a thickness of 30 μm (SPERIO; trade name, manufactured by Mitsubishi Plastics, Inc.) was used instead of the polyimide film. I got a board. The resin flow in the adhesive layer was 3.0%.

(Example 7) A polyphenylene sulfide film (Torrelina; trade name, manufactured by Toray Industries, Inc.) having a thickness of 30 μm was used in place of the polyimide film. Obtained. The resin flow in the adhesive layer was 3.0%.

(Comparative Example) An IVH-attached sheet was prepared in the same manner as in Example 1 except that an adhesive layer was formed directly on a copper foil having a thickness of 18 μm.
A layer printed wiring board was obtained. The resin flow in the adhesive layer was 3.0%.

With respect to the obtained four-layer printed wiring board with IVH, the surface step of the outer layer circuit, solder heat resistance, and coefficient of thermal expansion were measured. Table 1 shows the results. The solder heat resistance was measured by immersing the four-layer printed wiring board in a 260 ° C. solder bath until the blisters and peeling occurred. The surface step was measured by a surface roughness meter. The coefficient of thermal expansion was measured using TMA (thermomechanical analysis).

[0035]

[Table 1] Item Example 1 Example 2 Example 3 Example 4 Surface step (μm) 5 ≧ 3 ≧ 5 ≧ 3 ≧ Solder heat resistance 180 <120 150 180 < Thermal expansion coefficient (ppm / ° C) 30 40 30 25 Resin flow (%) 3.0 5.0 3.5 4.0 Item Example 5 Example 6 Example 7 Comparative example Surface step (μm) 5 ≧ 5 ≧ 5 ≧ 15 to 25 Solder heat resistance 120 120 90 180 < Thermal expansion coefficient (ppm / ° C) 55 50 40 45Resin flow (%) 3.0 3.0 3.0 3.0

The fillability of the adhesive into the inner layer circuit (line width 0.2 mm, line interval 0.1 mm) when the inner layer circuit board and the laminate were stacked and heated and pressed was determined in both Examples and Comparative Examples. It was good. The IVH penetration of the four-layer printed wiring board with IVH was good in both the examples and the comparative examples. Furthermore, CAF (Conductive anodic filamen
Regarding t), both the examples and comparative examples were good. Moreover, the flame resistance after removing the surface conductor from the four-layer printed wiring board with IVH by etching was VTM-0 of UL94 in each of Examples and Comparative Examples.

[0037]

The heat-resistant plastic film laminate of the present invention and the multilayer printed wiring board using the same have a resin flow of 3.0 to 5.0% on one side of the heat-resistant plastic film.
Since the adhesive layer is formed, the unevenness of the inner layer circuit appears on the surface, and the problem that hinders the formation of wiring can be solved. In addition, properties such as solder heat resistance, electric corrosion resistance, flame retardancy, and thermal expansion coefficient of the insulating layer are not reduced.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Takahiro Tanabe 1500 Ogawa Oji, Shimodate City, Ibaraki Pref.Hitachi Chemical Industry Co., Ltd.

Claims (5)

[Claims] 1. A heat-resistant plastic film laminate in which an adhesive layer is formed on one side of a heat-resistant plastic film, wherein the resin flow of the adhesive layer is 3.0 to 5.0%. 2. The heat-resistant plastic film laminate according to claim 1, wherein an adhesive layer is formed on one side of the heat-resistant plastic film and a copper foil is formed on the other side. 3. The heat-resistant plastic film laminate according to claim 1, wherein the adhesive layer contains an epoxy resin as a main component of the adhesive. 4. A multilayer printed wiring board using the heat-resistant plastic film laminate according to any one of claims 1 to 3 as an outer layer material. 5. A via hole is provided by laminating the heat-resistant plastic film laminate according to any one of claims 1 to 3 on a circuit-formed inner layer plate, using a laser. 2. The multilayer printed wiring board according to item 1.