JPH09116270A - Manufacture of multilayered wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method by which a multilayered printed wiring board on which the ruggedness of an internal-layer circuit does not appear can be manufactured. SOLUTION: Circuits are formed on one or both surfaces of an internal-layer material 3 constituted of an insulating matrix 1 composed of a semihardened adhesive component and a film forming component and copper foil stuck to one or both surfaces of the matrix 1 by machining the copper foil and two pieces of external-layer copper foil 5 are respectively put on the surfaces of the circuits 2 formed on the surfaces of the material 3 with insulating adhesive films 4 composed of a semihardened adhesive component and a film forming component in between and the semihardened adhesive components are hardened by pressing and heating the laminated body.

Description

Detailed Description of the Invention

[0001]

[0001] The present invention relates to a method for manufacturing a multilayer printed wiring board.

[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 a double-sided copper-clad laminated board with a circuit formed by etching or other method.An inner layer material and an outer layer material are stacked and bonded together to form a circuit on the outer layer material surface of the laminated board for multilayer printed wiring board. Obtained. A single-sided copper-clad laminate or copper foil is used as the outer layer material. An epoxy resin prepreg having a glass cloth as a base material is used for bonding the inner layer materials to each other and the inner layer material to the outer layer material. In recent years, along with the demand for smaller and lighter electronic devices, multilayer printed wiring boards have also been required to be thinner, and the insulating layer has a thickness of 30.
Wiring boards of -100 μm have also appeared. The adhesive material between the components of the multilayer printed wiring board forms an insulating layer,
It has also been proposed to use a glass cloth-free adhesive film to thin the insulating layer.

In recent years, multilayer printed wiring boards have been made into high-density wiring, and more and more places are used for electrical connection between one conductor layer and another conductor layer. For this reason, a through hole is provided that penetrates the wiring board, and copper plating is deposited on the inner wall of this through hole to electrically connect different conductor layers.
Holes will also be passed through layers other than the layers that make the necessary connections, and in layers that are unrelated to the connections, the holes must be avoided, and wiring must be performed, which reduces design flexibility and wiring density. It becomes an obstacle. Therefore, so-called interstitial via holes (IVH) have been formed in which not only the holes penetrating the entire wiring board but only the wiring layers that need to be connected are connected.

When the circuit of the surface conductor layer and the circuit of the adjacent inner layer conductor layer are connected by IVH, a hole for IVH is made in the outer layer material, and the hole is aligned with the conductor land of the inner layer material. The outer layer material and the inner layer material are superposed and laminated and integrated so that the holes for IVH are not filled with the adhesive resin, and then a through hole is provided which penetrates the entire obtained laminated body. A conductive metal is deposited on the inner wall of the hole by plating. After this, the outer layer copper is etched to form IVH.
Multi-layer printed wiring board. Such a method of laminating the pre-drilled components is referred to as a predrilling method.
Drilling, punching,
There is laser processing etc.

[0005]

When the copper foil is used as the outer layer material, the inner surface of the copper foil (the surface on the inner layer side) is previously prepared.
A laminated body having an adhesive layer formed thereon is used. When such an outer layer material is used for laminating and integration with an inner layer material on which a circuit has been formed, the copper foil has poor rigidity, and thus unevenness of the inner layer circuit appears on the surface. When the outer layer material is processed into a circuit, these irregularities impair the adhesion of the etching resist, making it impossible to form a fine pattern. Further, when the obtained printed wiring board is used as an inner layer material and further an outer layer material is laminated to obtain a high multilayer, the number of irregularities increases or the degree of irregularities increases, which is not preferable. An object of the present invention is to provide a method for manufacturing a multilayer printed wiring board in which unevenness of inner layer circuits does not appear on the surface.

[0006]

SUMMARY OF THE INVENTION The present invention comprises an insulating matrix 1 comprising a semi-cured adhesive component and a film-forming component, and a copper foil adhered to one or both sides of the insulating matrix 1. The inner layer material 3 is subjected to circuit processing, the outer layer copper foil 5 is superposed on the circuit surface 2 of the inner layer material 3 through the insulating adhesive film 4 composed of the semi-cured adhesive component and the film forming component, and heated. A method for producing a multilayer printed wiring board, which comprises applying pressure to cure the semi-cured adhesive component.

When the constituent materials are stacked and heated and pressed (hereinafter, simply referred to as "lamination"), the insulating matrix resin is softened and deformed, so that the inner layer circuit body sinks and the unevenness does not appear on the surface.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below. The adhesive component forming the insulating matrix has following properties to the inner layer circuit, adhesiveness, does not excessively flow into the holes provided prior to stacking, and has heat resistance necessary as a wiring board after stacking. Required. Therefore, it is preferable to use a thermosetting resin such as an epoxy resin or a phenol resin, particularly an epoxy resin, as the adhesive component.

The film-forming component is blended with the insulating matrix and the insulating adhesive film in order to improve the handling property during the laminating operation. As the film-forming component, a high molecular weight epoxy polymer having film-forming ability,
In particular, it is preferable to use 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 together with the high-molecular-weight epoxy polymer having film-forming ability, a film-forming polymer which is compatible with the high-molecular weight epoxy polymer and soluble in the same solvent. is there.

The inner layer material is obtained by temporarily adhering a film having an insulating matrix layer comprising a semi-cured adhesive component and a film-forming component on one surface of a copper foil, with the insulating matrix layers facing each other. . When the insulating layer is thin, a double-sided copper-clad film in which copper foil is laminated on both sides of a single insulating matrix film may be used.

The insulating adhesive film 4 for bonding the inner layer material 1 and the outer layer copper foil 5 is preferably integrated with the outer layer copper foil 5 in advance. This is because it is possible to perform pre-drilling and improve the stacking work efficiency.
The insulating adhesive film 4 needs to be flame-retardant.

It is necessary that the insulating matrix and the insulating adhesive film start to soften and flow during the temperature rising process during lamination molding, and at the same time, the curing reaction proceeds to prevent excessive flow. Therefore, the resin flow is 0.1-3.0%,
It is preferably adjusted to 0.5 to 1.5%. If the resin flow exceeds 3.0%, the resin leaches into the hole for IVH during the molding step, IVH conduction failure is likely to occur, and the resin becomes brittle, resulting in poor handleability. Also, the resin flow is 0.1%
If it is less than the range, followability to the inner layer circuit is poor, and voids are likely to occur. The resin flow can be controlled by controlling the curing reaction and composition of the adhesive component. That is, the required resin flow can be obtained by appropriately adjusting the molecular weight of the adhesive component, the type of the curing accelerator or the curing agent, the compounding amount, or the coating conditions.

It is preferable to use a thermosetting resin such as an epoxy resin or a phenol resin as the adhesive component. These thermosetting resins may be used alone or in combination, but in order to obtain good properties as a multilayer printed wiring board, it is desirable to use an epoxy resin combined with a curing agent. The epoxy resin may be any compound as long as it is a compound having two or more epoxy groups in the molecule, and examples thereof include phenol novolac type epoxy resin, cresol novolac type epoxy resin, resol type epoxy resin, and bisphenol type epoxy resin. Epoxy resin (phenolic epoxy resin) or alicyclic epoxy resin, which is a glycidyl ether of phenols such as
Examples thereof include epoxidized polybutadiene, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, and isocyanurate type epoxy resin. 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, and examples of the curing agent and the curing accelerator for the epoxy resin include novolac type phenol resin, dicyandiamide, acid anhydrides, amines, imidazoles and phosphines. And these are used alone or in combination.

A high molecular weight epoxy polymer is preferred as the film-forming component for use with the adhesive component. When only the high molecular weight epoxy polymer is used, it is necessary that the high molecular weight epoxy polymer has a weight average molecular weight of 100,000 or more and is soluble in a solvent. If the high molecular weight epoxy polymer is not soluble in the solvent, a varnish cannot be obtained, so unless a special method such as a resin kneading method is adopted, it does not form a film and cannot be substantially manufactured. .

When the weight average molecular weight of the high molecular weight epoxy polymer is less than 100,000, the strength at room temperature, the storage elastic modulus or the storage elastic modulus at the molding stage is liable to be lowered, and the handling property or the good handling property is good. It is difficult to obtain a multi-layer printed wiring board with a punched IVH. Therefore, the weight average molecular weight is 100,000 as the film-forming component.
When a high molecular weight epoxy polymer of less than 0 is used, it is an acrylic polymer which is compatible with the high molecular weight epoxy polymer and is soluble in a common solvent with the high molecular weight epoxy polymer and has a film-forming property. Rubber, nitrile rubber, butyral resin, polyvinyl alcohol, polyurethane,
It is necessary to use a combination of polyamide, polyester, polyether, polyolefin, or modified products thereof, etc. in order to obtain a good 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 bifunctional phenol, and a compounding equivalent ratio of the bifunctional epoxy resin and the bifunctional phenol is epoxy group / phenolic hydroxyl group = 1/09. The reaction solid content concentration is 50% in an amide-based or ketone-based solvent having a boiling point of 130 ° C. or higher by using an alkali metal compound, an alkaline earth metal compound, an imidazole, an organic phosphorus compound, an amine, etc. as a catalyst. It can be obtained by heating below and polymerizing.

In addition, performing the three-dimensionalization of the high molecular weight epoxy polymer in an appropriate manner using a cross-linking agent during the step of applying the insulating adhesive film makes it possible to form a multilayer printed wiring board without increasing the number of manufacturing steps. It is effective as a method for improving heat resistance, solvent resistance, water absorption and insulation reliability. Examples of the cross-linking agent include block-type polyisocyanates 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 be easily controlled in the reactivity of the crosslinking agent, can easily secure the storage stability of the adhesive varnish, and can be expected not to induce the characteristic deterioration of the insulating adhesive film and the multilayer printed wiring board is selected. It is desirable to use. As a block type polyisocyanate,
Tolylene diisocyanate (TD) blocked with phenol, oxime, alcohol, masking agent, etc.
I), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI) and the like. In order to improve the heat resistance of the multilayer printed wiring board, TDI blocked with a phenol novolac masking agent is preferable, but these masking agents and isocyanates may be used in combination.

In order to make the multilayer printed wiring board flame-retardant,
Halogenated, especially brominated, high molecular weight epoxy polymers are used or reactive flame retardants are incorporated. It is also possible to mix a phosphorus-based flame retardant, a nitrogen-based flame retardant, and an inorganic-based flame retardant, which are known as additive-type flame retardants to make them flame-retardant. Since the characteristics are poor, it is desirable to add a reactive flame retardant. As the reactive flame retardant, halogenated epoxy resin,
Preferably, a brominated epoxy resin or the like has a high flame-retardant effect and a uniform adhesive layer, and is optimal when the characteristics of the multilayer printed wiring board are taken into consideration. Polyfunctional halogenated phenols, especially polyfunctional brominated phenols, are preferred because they act as curing agents for the epoxy resin and provide good multilayer printed wiring board properties. In either case, the halogen content is preferably 10 to 40%, preferably 15 to 2
It is more preferably 5%.

A silane coupling agent is further added to the insulating matrix and the insulating adhesive film. This is to improve the adhesive force 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.

Each component is heated and pressed to form a multilayer printed wiring board. As the cushioning material placed between the end plate and the heating / pressurizing material, a cushioning material having a property of flowing at a molding temperature is preferable. Examples of such a cushion material include a polyethylene sheet and a polyvinyl chloride sheet having a film thickness of 40 to 100 μm. It is also preferable to use this cushion material in combination with another cushion material and a release sheet.

[0023]

【Example】

Example 1 100 parts by weight of a brominated high molecular weight epoxy polymer having a weight average molecular weight of 500,000, 20 parts by weight of tolylene diisocyanate (TDI) blocked with a phenol novolac acting as a crosslinking agent thereof, and a bisphenol A type epoxy resin 30. By weight, phenol novolac acting as a curing agent thereof was mixed in an amount equivalent to the epoxy resin, and 0.5 part by weight of a urea silane coupling agent was added to obtain a varnish having a resin content of 40%. This varnish was applied to a copper foil having a thickness of 18 μm and dried and cured at 100 ° C. for 1 minute and then at 150 ° C. for 1 minute to form an insulating adhesive film layer having a thickness of 50 μm and a copper layer with an adhesive layer having a bromine content of 25%. I was tired. The resin flow of the adhesive layer was 0.6%.
Five copper foils with an adhesive layer were piled up, and a hole having a diameter of 0.3 mm was made with an NC drill machine.

Separately, two copper foils with the same adhesive layer were stacked so that the copper foils were on the outside, and 1 at 140 ° C. and 2 MPa.
Heat and pressure were applied for 0 minutes for temporary adhesion, and copper foil was etched to form a circuit to obtain an inner layer material. The holes in the copper foil with the adhesive layer and the conductor lands of the inner layer material circuit are aligned and overlapped so that they overlap each other, sandwiched between a polyethylene sheet with a thickness of 40 μm and three pieces of kraft paper with a mirror plate, and vacuum-pressed. It was heated and pressed at 170 ° C. and 4 MPa for 30 minutes.
Subsequently, the obtained surface copper foil is processed to form a wiring pattern, and the portion which has been previously drilled and the conductor land portion of the inner layer circuit board are electrically connected by plating, thereby providing IVH 4
A layer printed wiring board was obtained.

Example 2 Weight average molecular weight of 5 instead of 100 parts by weight of brominated high molecular weight epoxy polymer having a weight average molecular weight of 500,000.
A 4-layer printed wiring board with IVH was obtained in the same manner as in Example 1 except that 80 parts by weight of a brominated high molecular weight epoxy polymer and 20 parts by weight of a modified acrylic rubber were blended. The resin flow of the adhesive layer was 0.80%.

Example 3 Weight average molecular weight 50 instead of 100 parts by weight of brominated high molecular weight epoxy polymer having a weight average molecular weight of 500,000.
50 parts by weight of a 0000 brominated high molecular weight epoxy polymer and 50 parts by weight of a non-brominated high molecular weight epoxy polymer having a weight average molecular weight of 500,000 are blended, and replaced with 30 parts by weight of a bisphenol A type epoxy resin. A 4-layer printed wiring board with IVH was obtained in the same manner as in Example 1 except that 15 parts by weight of bisphenol A type epoxy resin and 15 parts by weight of brominated bisphenol A type epoxy resin were mixed. The resin flow of the adhesive layer was 0.30%.

Example 4 A 4-layer printed wiring board with IVH was obtained in the same manner as in Example 1 except that the thickness of the copper foil was 12 μm and the thickness of the insulating adhesive film layer was 25 μm.

Example 5 A 4-layer printed wiring board with IVH was obtained in the same manner as in Example 1 except that the thickness of the copper foil was 9 μm and the thickness of the insulating adhesive film layer was 15 μm.

Comparative Example Copper foil An inner layer material obtained by subjecting a glass epoxy double-sided copper clad laminate having a thickness of 18 μm to circuit processing and the copper foil with an adhesive layer obtained in Example 1 were used. Similarly IVH
An attached 4-layer printed wiring board was obtained.

With respect to the obtained 4-layer printed wiring board with IVH, the surface step of the outer layer circuit, solder heat resistance, and thermal expansion coefficient were measured. In addition, the amount of resin flowing into the hole provided in the laminate after the lamination molding (the distance from the inner wall of the hole to the tip of the resin flowing into the hole) was examined. Table 1 shows the results. The solder heat resistance is measured by immersing the 4-layer printed wiring board in a solder bath at 260 ° C. and measuring the number of seconds until swelling / peeling occurs, and the surface step is measured by a surface roughness meter.

It is to be noted that five copper foils with an adhesive layer are stacked and NC
The drillability when drilling a diameter of 0.3 mm with a drill machine was good in both Examples and Comparative Examples.
In addition, the filling property to the inner layer circuit (line width 0.2 mm, line interval 0.1 mm) when the inner layer material and the copper foil with the adhesive layer are overlapped and heated and pressed is good in all the examples. An example was NG. The IVH penetration of the 4-layer printed wiring board with IVH was good in both Examples and Comparative Examples. In addition, CAF (Conductive)
As for the dic filament, both the examples and the comparative examples were good. Further, the flame resistance after removing the surface conductors from the IVH-attached four-layer printed wiring board by etching is UL94 VTM-in both Examples and Comparative Examples.
It was 0.

[0032]

[Table 1] ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Item Item Example 1 Example 2 Example 3 ───── ───────────────────────── Surface step (μm) 5 ≧ 5 ≧ 5 ≧ Solder heat resistance (seconds) 180 <120 150 Thermal expansion characteristics ( ppm / ° C) 40 55 45 Resin inflow amount (μm) 25 50 50 ────────────────────────────── Item Item Example 4 Example 5 Comparative example ────────────────────────────── Surface step (μm) 5 ≧ 5 ≧ 5 ≧ Solder heat resistance (Second) 180 <180 <180 <Thermal expansion characteristics (ppm / ° C) 40 40 30 Resin flow-in amount (μm) 25 25 25 ━━━━━━━━━━━━━━━━━━━━━ ━━━━━━━━━

[0033]

As described above, according to the present invention, an inner layer material comprising an insulating matrix composed of an adhesive component in a semi-cured state and a film-forming component, and a copper foil adhered to one side or both sides of the insulating matrix. The outer layer copper foil is laid on the circuit surface of the inner layer material through an insulating adhesive film consisting of a semi-cured adhesive component and a film-forming component, and heated and pressed to bond the semi-cured state. Since the conductive component is cured, a step due to the unevenness of the inner layer circuit does not appear on the surface, and a multilayer printed wiring board having excellent heat resistance can be manufactured.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view of a state before heating and pressurizing, and FIG. 1B is a cross-sectional view of a state after heating and pressing according to an embodiment of the present invention.

[Explanation of symbols]

 1 Insulation matrix 2 Circuit surface of inner layer material 3 Inner layer material 4 Insulating adhesive film 5 Outer layer copper foil

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] February 15, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0003

[Correction method] Change

[Correction contents]

[0003] Recent multilayer printed wiring board, and high-density wiring of, has many places to be used for electrical connection of one conductive layer and another conductive layer. For this reason, a through hole is provided that penetrates the wiring board, and copper plating is deposited on the inner wall of this through hole to electrically connect different conductor layers. Holes are also made to pass through layers other than the layers to be formed, and in layers unrelated to the connection, the holes must be avoided to perform wiring, which is an obstacle to the degree of freedom in designing and increasing the density of wiring. Therefore, what is called an interstitial via hole (I) is used in which only the wiring layer that needs to be connected is used instead of using only the hole penetrating the entire wiring board.
VH) is being formed.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction contents]

The high molecular weight epoxy polymer comprises a bifunctional epoxy resin and a bifunctional phenol, and a compounding equivalent ratio of the bifunctional epoxy resin and the bifunctional phenol is epoxy group / phenolic hydroxyl group = 1 / 0.0. 9 to 1.1, using an alkali metal compound, an alkaline earth metal compound, an imidazole, an organic phosphorus compound, an amine, etc. as a catalyst, and a reaction solid content concentration of 50 in an amide or ketone solvent having a boiling point of 130 ° C. or higher. % Or less to heat and polymerize.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0029

[Correction method] Change

[Correction contents]

[0029] Comparative Example Copper using an adhesive layer with copper foil obtained in the inner layer material and the first embodiment described facilities circuits working on a glass epoxy double-sided copper-clad laminate of the Ku thickness 18 [mu] m, similar to the following Example 1 Thus, a 4-layer printed wiring board with IVH was obtained.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0032

[Correction method] Change

[Correction contents]

[0032]

[Table 1] ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Item Item Example 1 Example 2 Example 3 ───── ───────────────────────── Surface step (μm) 5 ≧ 5 ≧ 5 ≧ Solder heat resistance (seconds) 180 <120 150 Thermal expansion characteristics ( ppm / ° C) 40 55 45 Resin inflow amount (μm) 25 50 50 ────────────────────────────── Item Item Example 4 Example 5 Comparative Example ────────────────────────────── Surface step (μm) 5 ≧ 5 ≧ 15 ≧ Solder heat resistance (Second) 180 <180 <180 <Thermal expansion characteristics (ppm / ° C) 40 40 30 Resin flow-in amount (μm) 25 25 2 ━━━━━━━━━━━━━━━━━━━━━━ ━━━━━━━━━

Claims (6)

[Claims] 1. An inner layer material composed of an insulating matrix composed of an adhesive component in a semi-cured state and a film-forming component, and a copper foil adhered to one or both sides of the insulating matrix is subjected to circuit processing, An outer layer copper foil is placed on the circuit surface of the inner layer material through an insulating adhesive film consisting of a cured adhesive component and a film-forming component, and heated and pressed to cure the semi-cured adhesive component. A method for manufacturing a characteristic multilayer printed wiring board. 2. A composite in which an inner layer material is a copper foil, on one side of which a film having an insulating matrix layer comprising a semi-cured adhesive component and a film-forming component is formed, and the insulating matrix layers are faced to each other for temporary adhesion. The method for producing a multilayer printed wiring board according to claim 1, which is a sheet. 3. The method for producing a multilayer printed wiring board according to claim 1, wherein the adhesive component of the insulating matrix and the insulating adhesive film is an epoxy resin. 4. The insulating matrix and the film forming component of the insulating adhesive film are high molecular weight epoxy polymers having film forming ability.
2. The method for manufacturing a multilayer printed wiring board according to 2 or 3. 5. The method for producing a multilayer printed wiring board according to claim 4, wherein the high molecular weight epoxy polymer having film forming ability has a weight average molecular weight of 100,000 or more. 6. The insulating matrix and the film-forming component of the insulating adhesive film are composed of a high molecular weight epoxy polymer and a film forming polymer which is compatible with the high molecular weight epoxy polymer and soluble in the same solvent. The method for manufacturing a multilayer printed wiring board according to claim 1, 2, or 3.